EP3947321A1 - Granulés d'engrais à base de phosphate secondaire appauvris en métaux lourds et procédé de production associé - Google Patents

Granulés d'engrais à base de phosphate secondaire appauvris en métaux lourds et procédé de production associé

Info

Publication number
EP3947321A1
EP3947321A1 EP19835293.2A EP19835293A EP3947321A1 EP 3947321 A1 EP3947321 A1 EP 3947321A1 EP 19835293 A EP19835293 A EP 19835293A EP 3947321 A1 EP3947321 A1 EP 3947321A1
Authority
EP
European Patent Office
Prior art keywords
raw material
heavy metal
depleted
phosphate
precipitation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP19835293.2A
Other languages
German (de)
English (en)
Inventor
Frank Thoralf Hager
Matthias Hoger
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pontes Pabuli GmbH
Original Assignee
Pontes Pabuli GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Pontes Pabuli GmbH filed Critical Pontes Pabuli GmbH
Publication of EP3947321A1 publication Critical patent/EP3947321A1/fr
Pending legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05B—PHOSPHATIC FERTILISERS
    • C05B17/00—Other phosphatic fertilisers, e.g. soft rock phosphates, bone meal
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05B—PHOSPHATIC FERTILISERS
    • C05B5/00—Thomas phosphate; Other slag phosphates
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05D—INORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C; FERTILISERS PRODUCING CARBON DIOXIDE
    • C05D9/00—Other inorganic fertilisers

Definitions

  • Agricultural use removes mineral raw materials from the soil, such as compounds containing phosphorus, which have to be compensated for by adding mineral fertilizers.
  • the material and energetic use of biomass, such as from household waste or sewage sludge, is associated with a withdrawal of nutrients and considerable amounts of organic matter from the natural material cycles.
  • the preservation of the fertility of the soil through the use of artificial mineral fertilizers from fossil resources is to be assessed critically from an ecological point of view, on the one hand because of the environmentally destructive degradation and on the other hand because of the heavy metal input into the soil through mineral fertilizers.
  • Phosphorus is a limited raw material and its efficient use for fertile soil in the context of a growing world population is of great importance. From the point of view of sustainability, the closure of natural nutrient cycles is becoming more and more important and also offers a local source of raw materials that has so far only been used to a limited extent.
  • Organic residues such as sewage sludge, digestate or liquid manure, are in principle a cost-effective and sustainable alternative to mineral fertilizers and thus to close the nutrient cycle. Some of these organic residues are still applied directly to fields. For some time now, however, the acceptance of this recycling method has been decreasing progressively, since direct application leads to undesirable odor nuisance and the associated cycles are suspected of leading to an undesired concentration of certain pollutants, such as perfluorinated surfactants (PFT) and various heavy metals. Sewage sludge that has not been subjected to any hygienic treatment can also contain a large number of epidemic and phytosanitary pathogens such as bacteria, viruses, parasites and worm eggs. If the organic residues are to be recycled in agriculture, there is a fundamental risk that pathogens can reach humans and animals via food and feed and thus endanger them.
  • PFT perfluorinated surfactants
  • thermochemical, thermoelectric and wet-chemical approaches The processes for obtaining phosphate from sewage sludge ash can generally be subdivided into thermochemical, thermoelectric and wet-chemical approaches.
  • wet chemical process numerous different concepts are pursued, with a general distinction between processes in which the acid is only mixed with the ash and fertilizer is made from it, and processes in which phosphorus is extracted from the ash and thus brought into the liquid phase becomes.
  • the wet chemical processes in which basically only ash is mixed with acid, in particular earth-moist, in order to produce fertilizer from it, are economical.
  • the largely insoluble phosphate from phosphate-containing ashes is digested using mineral acid.
  • mineral acid Such a method is known from DE 10 2010 034 042 B4, for example.
  • the process produces a phosphate or multi-nutrient fertilizer by mixing ashes from sewage sludge mono-incineration with mineral acid with the addition of potassium and / or a nitrogen carrier.
  • the mineral acid breaks down the poorly soluble phosphate compounds in the sewage sludge ash.
  • the desired conversion reactions and granulation take place largely simultaneously. Mixing, reaction and granulation take place in a mixing apparatus.
  • Ploughshare mixers with a set of knives, a continuously operating continuous mixer or a twin-shaft paddle mixer are proposed for this purpose.
  • the resulting nutrient composition can be adapted to the needs of the soil and plants.
  • a method is known in which a suspension of at least one phosphate-containing secondary raw material and at least one mineral acid is first produced, then the poorly soluble phosphates of the phosphate-containing secondary raw material are at least partially dissolved in the suspension produced and / or in a water- and / or neutral ammonium citrate-soluble phosphate phase are converted and finally this suspension is fed to a granulation, the fertilizer granules being formed and the P205 content contained in the fertilizer granules being more than 75% neutral ammonium citrate-soluble.
  • this document describes the fact that by generating a raw material dispersion, the reaction, which sometimes occurs spontaneously and violently when the phosphate-containing secondary raw materials and the mineral acid are brought together, should be manageable, controllable and controllable by the process.
  • the suspensions produced in this process have a significantly higher proportion of water than in comparison to processes in which the phosphate-containing ones Secondary raw materials and diluted or undiluted mineral acid are mixed directly, quasi-moist, and optionally granulated (for example as described in DE 10 2010 034 042 B4). This higher proportion of water is intended to act as a buffer.
  • the suspension produced in this way is fed to a granulation, whereby the fertilizer granules are formed.
  • the heavy metals can be at least partially separated, but considerable process residues are created. All these processes have in common that by mixing the sewage sludge ash with mineral acid, depending on the type and concentration of the mineral acid and depending on the process management, a large part of the phosphate in the ash is dissolved, but a considerable proportion of undissolved components remains. Subsequently, in this process, the phosphate-containing solution is very expensive and processed further through very complex precipitation or extraction processes. In contrast, it is advantageous in this process that the phosphate-containing solution obtained is at least partially freed from heavy metals and these heavy metals are discharged from the process.
  • a method for the production of a phosphate-containing fertilizer from an ash or a char residue of a sludge from a waste water treatment or waste fermentation is known.
  • an ash or the charring residue is mixed with a mineral acid and the resulting suspension is incubated in a first vessel, then moist solids are separated from the suspension and the separated solids are replaced by further ash or further charring residue, the further ash is mixed or the further charring residue with the mineral acid remaining in the first vessel and incubation of the resulting suspension in the first vessel.
  • the separated solid is transferred to a second vessel and mixed there with a pH-neutral, basic or buffered aqueous liquid, then part of the liquid resulting from the mixing is separated from the second vessel, the heavy metal ions contained in it are separated from it and this liquid is transferred the second vessel returned.
  • ion exchangers activated carbon, Bacteria, fungi, algae, a biomass from bacteria, fungi or algae, the use of precipitants and / or a nanofilter and / or electrolytically proposed.
  • the disadvantage of this process is that the phosphate solubility of the ash is increased sufficiently in the first batch at best; with each subsequent batch, the solubility decreases until there is ultimately no change compared to the initial ash. This means that a suitable supply of nutrients for the plants cannot be given within one growth period.
  • ammonium-sulphate-containing solutions In addition to the recycling of phosphate-containing ashes, the recycling of ammonium-sulphate-containing solutions is also an economic problem. In principle, ammonium sulphate-containing solutions, such as those obtained in considerable quantities in waste gas scrubbers and especially in biogas plants, are untreated or conditioned and very suitable as fertilizers apply accordingly.
  • the prior art describes pedosphere-improving granules, which, however, often have a disadvantageous effect. Many of these known structures have a positive effect on plant growth, but this is associated with negative effects on microorganisms and microorganisms. It has been observed several times that granules of the prior art, for example, reduce the number of earthworms and that fewer nitrogen-assimilating microorganisms continue to occur in the soil. While in the past the reduction of such soil organisms was considered to be of little relevance, today we know that the organisms mentioned are central to the quality of soils. In particular, soils that are exposed to strongly changing weather conditions, such as high temperatures or heavy rain, require a healthy biomass, such as B. insects, nematodes or annelids, in order to ensure high yields in plants even under highly fluctuating weather conditions.
  • the invention is therefore based on the object of providing new, improved and heavy metal-depleted granules which optimize the pedosphere with regard to soil flora and fauna.
  • the soil flora mainly includes plant or non-animal organisms, such as Bacteria, ray fungi, fungi, algae and lichens.
  • the soil fauna is composed of animal protozoa and multicellular organisms, which are differentiated according to their size into microfauna ( ⁇ 0.2 mm; e.g. ciliates, flagellates, amoebas, small roundworms), mesofauna ( ⁇ 2 mm; e.g. springtails, rotifers , Mites), macrofauna (> 2 mm; e.g.
  • bristle worms woodlice, insects
  • megafauna > 20 mm; e.g. vertebrates such as voles, shrews, moles.
  • the optimization primarily affects the improved plant growth as well as the growth of bacteria, flagellates, nematodes, annelids or insects and others.
  • the present invention is also based on the object of providing an economical, ecological, flexible, simple and technically feasible method for the production of soil- and / or plant-specific, heavy metal-depleted fertilizers with exactly adjustable nutrient composition in granulate form.
  • the method according to the invention is intended to enable a wide variety of inorganic secondary phosphates to be processed efficiently and inexpensively, with soil- and plant-specific fertilizer compositions also being provided in a targeted manner, with a large part of the phosphate in the resulting fertilizer granules being in a form readily available to plants and at least part of the heavy metals being separated off is.
  • solutions containing ammonium sulfate should be inexpensive and technologically easy to integrate and use as a further nutrient.
  • a fertilizer is to be provided that can be used and / or used as a pedophore improver in agriculture, forestry or horticulture.
  • a heavy metal-depleted, pedoshare-improving granulate is provided that is produced using a method that comprises the following steps:
  • a raw material suspension is produced from at least one inorganic secondary phosphate (1) and at least one reactant.
  • the phosphate is converted from the inorganic secondary phosphate, which is insufficiently soluble in the inorganic secondary phosphate, that is to say is insufficiently available to plants.
  • the conversion of the phosphate takes place by reaction with a reaction agent with the aim of considerably improving the solubility and thus the availability of this phosphate to plants.
  • a reactant is to be understood as a substance, such as acid or alkali, which on the one hand dissolves at least part of the phosphate supplied by the inorganic secondary phosphate and / or reacts with it.
  • Reactants are for example
  • this reaction between the inorganic secondary phosphate and the reactant takes place in a raw material suspension.
  • the reaction that takes place in a raw material suspension can be controlled and monitored.
  • the liquid phase required to form the raw material suspension results either from the fact that the reaction agent is a solution or suspension or is added specifically in addition to the inorganic secondary phosphate and reactant, for example in the form of water.
  • the proportion of the liquid phase and the composition of the suspension are essential control variables for the desired reaction between inorganic secondary phosphate and reactant, and the resulting solubility of the converted phosphate as a reaction product can thus be adjusted.
  • the inorganic secondary phosphate contains heavy metals.
  • the reactant should also at least partially dissolve the heavy metals present in the inorganic secondary phosphate.
  • the type and concentration of the reactant and the amount of liquid phase can be used to set the rate of dissolution and the proportion of heavy metals dissolved.
  • Step b) calls for an incubation time, which means that the reaction agent is allowed to act on the inorganic secondary phosphate.
  • Targeted setting of this reaction time influences the progress and scope of the reaction. On the one hand, this enables the proportion of dissolved heavy metals to be controlled. On the other hand, the solubility of the resulting phosphate after the conversion can also be adjusted via the reaction time.
  • Step c) describes the electrochemical heavy metal depletion according to the invention directly in the raw material suspension produced.
  • Electrochemical heavy metal depletion is defined as the chemical separation reactions taking place with the participation of electrons that flow through an external conductor circuit.
  • the electrodes are the active components in the electrochemical reaction, on the surfaces of which the heavy metals attach or adhere. This means that the heavy metals dissolved in the previous steps by the reactant and thus present dissolved in the suspension are deposited on the electrode or adhere to it through an electrochemical process. Following this electrochemical process, the electrode with the heavy metal-containing adhesions is spatially separated from the suspension. This removes the heavy metals adhering to the electrode from the suspension.
  • the heavy metal-containing adhesions on the electrode are detached and a heavy metal-containing portion is discharged from the raw material suspension.
  • This electrochemical reaction assumes that the heavy metals are at least partially dissolved.
  • inorganic secondary phosphate are combined with the heavy metals and reactants contained therein, as a result of which the reaction according to the invention begins between the two components.
  • the reaction according to the invention begins between the two components.
  • the heavy metals contained in the inorganic secondary phosphate are at least partially dissolved.
  • the reactant thus has the additional function of at least partially dissolving heavy metals from the inorganic secondary phosphate.
  • the heavy metals are dissolved out of the inorganic secondary phosphate, which takes place as a function of the reaction kinetics.
  • the electrochemical heavy metal depletion can in principle begin with or during the production of the raw material suspension or afterwards, since then proportionally dissolved heavy metals are already present.
  • the electrochemical depletion process takes place parallel to the incubation time according to step b). Since the electrochemical reaction is also time-dependent, the incubation time can advantageously be used, which shortens the overall time of the process. The electrochemical reaction can also take place beyond the incubation period.
  • step c) can also take place after the incubation time according to step b), for example in a separate vessel or in a separate flow-through circuit.
  • step d) After the electrochemical depletion, granulation or extrusion takes place in step d) with the aim of forming heavy-metal-depleted, pedosphere-improving granules.
  • the type of granulation or extrusion depends on the technical requirements and, in particular, on the consistency and processing properties of the heavy metal-depleted raw material dispersion. Pumpable and sprayable heavy metal-depleted raw material dispersions can be processed, for example, by spray granulation.
  • the earth-moist, heavy-metal-depleted raw material dispersion thus formed can, for example, be processed by means of a granulating plate or an extruder.
  • the granules or extrudates formed by granulation and extrusion are often unsuitable for storage or direct use. Subsequent drying, for example, usually increases strength and storage stability. Defined grain fractions are often required for the application, which is achieved through appropriate fractionation.
  • Steps a) to d) can be implemented in batches and / or continuous processes, it being possible for buffer containers to be used between the process steps.
  • buffer containers To implement all or individual process steps, a single unit and / or, in particular to map larger production quantities, several identical or similar units can be used. Several units in one or more process steps can be connected in parallel and / or alternately.
  • the process steps are carried out batchwise and / or continuously, for example, continuously until the desired production amount is reached, i.e. steps a) to d) are repeated correspondingly often.
  • the method according to the invention provides an economical, ecological, flexible, simple and technically feasible method for the production of soil- and / or plant-specific, heavy metal-depleted fertilizers with precisely adjustable nutrient composition in granular form, which has numerous technological advantages over the prior art, such as:
  • the process design according to the invention solves the existing technical problems of the process in which ash is mixed with acid in a quasi-earth-moist manner in order to produce fertilizers therefrom, as are known, for example, from the publication DE 10 2010 034 042 B4.
  • the reaction between inorganic secondary phosphate and mineral acid (here reactant) can hardly be monitored and controlled. This means that the solubility and plant availability cannot be precisely adjusted.
  • the reaction superimposes the granulation process when the reaction is carried out, which is therefore hardly controllable.
  • Such processes are technically hardly controllable.
  • the resulting inferior product quality also fluctuates greatly.
  • the reaction in the raw material suspension makes the reaction controllable and controllable.
  • the process according to the invention results in a very well digested and therefore specifically plant-available phosphate fertilizer.
  • the phosphate from the inorganic secondary phosphate is broken down significantly less strongly by the process management and is thus made less readily and less specifically available to plants.
  • the method offers heavy metal depletion, the methods proposed there are not as practicable and not as cost-effective as in the method according to the invention with electrochemical heavy metal separation.
  • solubility of phosphate There are a number of different methods for determining the solubility of phosphate, which differ in the dissolution procedure and the dissolution medium (water, citric acid, neutral ammonium citrate, etc.). Correspondingly, different information on solubility results from the process.
  • solubilities of the various dissolution processes cannot be converted into one another in a generally valid way, for example with an approximately fixed factor. Nor does a trend have to be concurrent.
  • solubility with one dissolving medium and with different dissolving media, which vary considerably in tendency and relationship. For example, inferring that the solubility in water is neutral in terms of ammonium citrate solubility is not permitted.
  • a significant improvement in the solubility of the phosphate is achieved from the inorganic secondary phosphate.
  • This increase in the neutral ammonium citrate solubility based on the phosphate from the inorganic secondary phosphate alone is at least 20%, and a neutral ammonium citrate solubility of greater than 60% based on the phosphate content from the inorganic secondary phosphate is achieved.
  • the method according to the invention provides new, improved and heavy metal-depleted fertilizer granulates which optimize the pedosphere in terms of soil flora and fauna and are sustainable and environmentally friendly due to the heavy metal reduction.
  • the invention relates to a process for the production of these heavy metal-depleted, pedosphere-improving granulates, which comprises the process steps mentioned.
  • a precipitation and / or crystallization product from an ammonium- and sulfate-containing starting solution is provided, which is produced using a method which comprises the following steps:
  • the generated precipitation and / or crystallization products can be used in the process for the preparation of the heavy metal-depleted, pedophore-improving granules and / or used separately therefrom.
  • the invention relates to a method for the preparation of this precipitation and / or crystallization product, which comprises the process steps mentioned.
  • the invention relates to a combined method for the production of a precipitation and / or crystallization product according to the above-mentioned process steps with the method for the production of heavy metal-depleted, pedophore-improving granules according to the above-mentioned process steps.
  • a particular advantage of the proposed granules and the proposed method is that the neutral ammonium citrate solubility of the phosphate supplied with the inorganic secondary phosphate is increased by reaction with the at least one reactant and the P205 content from the inorganic secondary phosphate in the fertilizer granules is more than 60% neutral ammonium citrate soluble is.
  • the term "P205 portion” preferably describes the portion of P205 in the fertilizer granulate.
  • the total amount of phosphorus (P) and heavy metals such as lead, cadmium, nickel are determined by means of inductively coupled plasma atomic emission spectrometry (ICP- OES) in accordance with DIN EN ISO 11885: 2009.
  • the sample to be determined is first digested with an aqua regia digestion in accordance with DIN EN 13346: 2001-04.
  • Different methods in particular different extraction methods, are known for determining the soluble phosphate content.
  • the availability of fertilizers is examined in the laboratory with different solvents and marked accordingly.
  • the most important solvents used are water, ammonium citrate, citric acid, formic acid and mineral acids.
  • the EU fertilizer regulation also standardizes various methods for determining the phosphate solubility of fertilizers to Different methods can be used for the origin and nature of the P fertilizer to be tested.
  • the extraction of the water-soluble phosphorus (P) takes place in accordance with DIN EN15958: 2011.
  • the phosphorus (P), which is soluble in neutral ammonium citrate, is extracted in accordance with DIN EN15957: 2011.
  • the 2% citric acid soluble phosphorus (P) is extracted in accordance with DIN EN15920: 2011.
  • the phosphate content (P) is then determined by means of inductively coupled plasma atomic emission spectrometry (ICP-OES) in accordance with DIN EN ISO 11885: 2009.
  • ICP-OES inductively coupled plasma atomic emission spectrometry
  • the phosphorus content which is soluble in neutral ammonium citrate, can be used as an indication of the medium-term availability of fertilizer phosphorus to plants, i.e. H. over the period of about one crop rotation.
  • the immediately available P component of a fertilizer is described by its solubility in water. The higher the water-soluble P component, the faster or easier the availability of the fertilizer phosphorus for the plant. Stronger solvents such as citric or formic acid also dissolve P components that are only available to plants over the long term or only under certain site conditions such as low pH values.
  • the present invention fulfills the requirement for high neutral ammonium citrate-soluble phosphate proportions by using the proposed method fertilizer granulates with a particularly high neutral ammonium citrate-soluble P205 proportion of greater than 60%, preferably greater than 70%, particularly preferably greater than 80% of the total P205 proportion are provided in the fertilizer granulate.
  • fertilizers are substances or mixtures of substances that supplement or adjust the nutrient supply for the cultivated plants, in particular crops, in agriculture, forestry and horticulture, and they can optionally be combined with other materials and / or functionalized.
  • Both single nutrient fertilizers such as phosphate fertilizers and complex fertilizers are understood as fertilizers.
  • Fertilizers in granular form, i.e. Fertilizer granulate is a pile typically in an approximately spherical shape and sufficient inherent strength with an average granulate size of 0.5-10 mm, preferably 1-7 mm, very particularly preferably 2-5 mm.
  • examples of inorganic secondary phosphates are ash and / or slag from the mono- or co-incineration of sewage sludge, ash and / or slag from the incineration or co-incineration of animal excrement, animal meal, animal remains and carcasses or ashes / slag from the incineration of liquid manure and digestate as Single substance or mixtures thereof.
  • inorganic fertilizers as is characteristic of typical conventional fertilizers, an organic proportion of less than 3%, often less than 1 % required.
  • the inorganic secondary phosphate should initially make it possible in principle to produce such inorganic fertilizers.
  • Organic residues such as sewage sludge in particular, or liquid manure or digestate with a typical organic content of 40-90% (TS), are expressly excluded from the definition of inorganic secondary phosphate.
  • the phosphate present in these substances is in a different, more readily plant-available bond form than, for example, in cremation ashes. Sewage sludge has been used for fertilization for decades, as the phosphates are sufficiently available to plants there. The digestion (reaction with the reactant) required according to the invention to increase the phosphate solubility is not required for these substances.
  • the phosphorus compounds contained in the inorganic secondary phosphate are referred to here as phosphate, even if in their entirety this should not or not completely correspond to the type of binding of the phosphorus in individual cases.
  • a reactant is to be understood as meaning a substance or a mixture which on the one hand dissolves at least part of the phosphate supplied by the inorganic secondary phosphate and / or reacts with it and on the other hand at least some of the heavy metals from the inorganic Dissolves secondary phosphate.
  • Reactants are, for example, organic or inorganic acids or acid mixtures or bases or mixtures of different bases, in each case in undiluted or diluted form.
  • the sum of the liquid substances in a coherent system is defined as the liquid phase (also liquid phase).
  • the raw material suspension consists of a solid and a liquid phase.
  • the solid phase is the sum of the undissolved substances.
  • the liquid phase in a system can be formed from different liquid components.
  • liquid components can be supplied at least partially in the form of moisture, partially in a suspension or as a liquid via various substances or, for example, as water or at least partially in the reactant, for example liquid, in particular, dilute acids.
  • moisture corresponds in the sense of the invention to the physically bound water that adheres to the substance or mixture of substances.
  • moisture is also used synonymously with the term “moisture content”.
  • the moisture or the moisture content is gravimetric in the context of the present invention determined according to DIN 52183. In the gravimetric moisture determination, also known as the Darr method, the sample is first weighed and then dried to constant weight in a drying oven at 105 ° C. The free water contained in the sample escapes in context corresponds to the present invention of the moisture or the moisture content. Since the liquid phase can also contain dissolved components that remain as solids during drying, the percentage of the liquid phase is usually significantly higher than the moisture.
  • earth-moist defines a consistency.
  • a concrete with a stiff consistency with a water-cement value ⁇ 0.40 is generally referred to as earth-moist concrete.
  • an earth-moist raw material mixture is a consistency range of the raw material mixture comparable to a consistency
  • the consistency range according to the invention is limited by a relatively dry mixture, but with more than 5% moisture (based on the raw material mixture), which cannot be shaped by hand, i.e. does not yet disintegrate like powder
  • the range is limited by the fact that the raw material mixture can be balled and shaped in the hand (comparable to a snowball) and does not dissolve without the application of force (such as vibration).
  • a suspension (Latin suspendere, hang up ',' to let in suspension ') is a heterogeneous mixture of substances made up of a liquid and finely distributed solids (particles), whereby the particles in the liquid are at least partially and at least temporarily in suspension, even if a weaning behavior can set in.
  • the solids are "suspended" in the liquid phase.
  • the liquid referred to as moisture in the earth-moist and / or easily plastically malleable mixture is physically bound or adhered to the solid or is largely in the form of so-called pore water.
  • An earth-moist mixture can also be referred to as a dispersion. According to the definition here, dispersions contain at least one solid and at least one liquid phase. A suspension or an earth-moist mixture also apply here accordingly as a dispersion.
  • the raw material suspension in the proposed method is produced from at least one inorganic secondary phosphate and at least one reactant, the proportion of liquid phase being greater than 45% and the incubation time between inorganic secondary phosphate and reactant being between 1 and 300 minutes.
  • the raw material suspension that is used in the context of the proposed method has a significantly higher proportion of liquid phase than in comparison to conventional methods known from the prior art. It is known in the prior art that the phosphate ashes are mixed with mineral acid directly and moistly and at the same time granulated.
  • the production of a raw material suspension with a significantly higher proportion of liquid phase which is provided in the context of the proposed invention, therefore has considerable technical advantages. For example, when the phosphate-containing secondary raw materials are mixed with the mineral acid, the reactions, which often take place spontaneously and are sometimes very exothermic, can be monitored and controlled.
  • the higher proportion of the liquid phase according to the invention advantageously acts as a reaction buffer. A raw material suspension with a significantly higher proportion of the liquid phase is also significantly less sticky.
  • the raw material suspension produced contains a proportion of liquid phase of preferably greater than 45%.
  • reactions can occur depending on the type of composition and the chemical-physical parameters of the raw material suspension (such as pH value or temperature), which lead to an increase in viscosity, for example through a type of gelation. This is undesirable because it impairs the processability (such as stirring, pumping, etc.).
  • suitable additives such as dispersants.
  • the proportion of liquid phase in the raw material suspension is set to greater than 60%.
  • the raw material suspension after the incubation time provided according to the invention, preferably contains an undissolved solid phase, which is preferably also referred to as the undissolved solids content, of less than 40%.
  • the undissolved solid phase is to be understood as the total solids content in the raw material suspension, i.e. also any solid that may have formed through, for example, precipitation or crystallization in the raw material suspension. A particularly good and simple homogenization of the raw material suspension produced is possible in this solids content range.
  • the raw material suspension contains an undissolved solids content (solid phase) of less than 30% after the incubation time provided according to the invention. Under such conditions, the rate of dissolution is relatively high, as a result of which the necessary reaction time can advantageously be shortened.
  • the production of the raw material suspension can also advantageously solve the corrosion problems.
  • the reaction between the inorganic secondary phosphate and the reactant can preferably take place in an acid-proof stirred tank with an acid-proof stirrer, after this reaction the majority of the free acid or alkali is used up and is therefore less harmful to the following system parts.
  • the pH of the raw material suspension produced can also be increased further if necessary after the reaction.
  • the pH should not exceed 3, very particularly preferably 2.
  • the heavy metals typically begin to precipitate, for example as hydroxides.
  • a complexing agent for example citric acid
  • the pH can be adjusted to up to 5, particularly preferably up to 4. In this way, for example, a further neutralization of the raw material suspension is achieved.
  • one or more liquid components can be added to the raw material suspension, for example water and / or liquid nutrient-containing solutions.
  • Nutrient-containing solutions preferably contain nutrients and / or trace substances that are contained in the proposed fertilizer granules.
  • a solution containing at least ammonium and sulfate is added.
  • the phosphate contained in the inorganic secondary phosphate is made available to plants as a nutrient in the method according to the invention.
  • a high phosphate nutrient content in the inorganic secondary phosphate is therefore particularly advantageous for the nutrient content of the fertilizers produced and increases the economic efficiency of the process. That in the inorganic Phosphate contained in secondary phosphate is used advantageously as a nutrient component in the fertilizer produced. High phosphate contents, especially in the case of inorganic secondary phosphate, are accordingly desirable here.
  • Inorganic secondary phosphates with greater than 10% P205, particularly preferably greater than 13% P205 and very particularly preferably greater than 16% P205, are therefore preferred.
  • P205 proportions of greater than 10% are preferred, particularly preferably greater than 13% and very particularly preferably greater than 16%. Therefore, preference is given to ashes and / or slag from the individual or combined thermal utilization (incineration) of sewage sludge, animal excrement, animal meal, animal remains and / or animal carcasses as individual substances or mixtures thereof as inorganic secondary phosphates with the typical P205 contents of over 10 % and above.
  • the inorganic secondary phosphate can contain other components. It is advantageous if further nutrient components are included, such as N, K, Mg or other trace nutrients.
  • the inorganic secondary phosphate (s) reacts with at least one reactant.
  • the solubility of the phosphate contained in the inorganic secondary phosphate is advantageously increased. Since there is also a heavy metal depletion, it is preferred in the context of the invention that the reactant is set up to also dissolve a portion of the heavy metals contained - preferably as high as possible.
  • the phosphate fraction present in the inorganic secondary phosphate typically has a relatively low solubility. Accordingly, substances such as sewage sludge ash are only suitable to a limited extent as fertilizers. Typically, these inorganic secondary phosphates show a water solubility of less than 30% and a neutral
  • Ammonium citrate solubility of less than 50%, preferably based in each case on the total phosphate content in the inorganic secondary phosphate.
  • this insufficiently soluble phosphate is converted into a more soluble and therefore more readily available to plants.
  • the conversion takes place by at least partial reaction of the inorganic secondary phosphate with at least one reactant.
  • the reactant is preferably set up to dissolve at least part of the phosphate contained in the inorganic secondary phosphate and / or to react with this in such a way or to convert the phosphate by reaction so that a phosphate that is more neutral-ammonium citrate-soluble is formed.
  • the phosphate which is preferably dissolved by the reactant, advantageously forms a more neutral-ammonium citrate-soluble phosphate than in the inorganic secondary phosphate.
  • the term "better neutral ammonium citrate solubility" in the context of the invention preferably means that the neutral ammonium citrate solubility of the phosphate in the inorganic secondary phosphate is higher after the reaction with the reactant. An increase in the neutral ammonium citrate solubility of greater than 20% is preferred, especially an increase of greater than 50% is preferred.
  • a corresponding calculation example can look like this: the neutral ammonium citrate solubility of the phosphate content from the untreated secondary phosphate from 50% is increased by 20% to 60% due to the reaction with the reactant
  • the proposed method differs from the state of the art in that the phosphate at least partially reacts and the solubility is increased.
  • the type and concentration of the reactant, the conduct of the reaction and the reaction time can influence the resulting neutral ammonium citrate solubility of the inorganic secondary phosphate.
  • the phosphate content from the inorganic secondary phosphate is then preferably present in the heavy metal-depleted phosphate produced Fertilizer granules have a neutral ammonium citrate solubility of greater than 60%, preferably greater than 70%, particularly preferably greater than 80%.
  • the preferred reaction or conversion of the phosphate and the preferred resulting neutral ammonium citrate solubility from the inorganic secondary phosphate advantageously result in a better availability of phosphate in plants and thus an improved fertilizing effect.
  • the solubility of the phosphate from the inorganic secondary phosphate is increased by the reaction between the inorganic secondary phosphate and the reactant.
  • the solubility of phosphate in fertilizers is determined using different methods.
  • the P solubility is preferably determined by the type of P bond and the solution medium.
  • the way in which the reaction is carried out in process step a) can influence the binding of the P, that is to say the phosphate phases that form. This can be done, for example, by the type and concentration of the reagent, the reaction time and / or the process temperature.
  • the reaction is preferably controlled so that the phosphate content from the inorganic secondary phosphate then has a neutral ammonium citrate solubility of greater than 60% and a water solubility of less than 40% in the fertilizer granules produced.
  • the solubilities in this form, the effect is that the phosphate is actually sufficiently readily available to the plants in the field for about one growth period, but is not washed out during this time. Leaching can typically take place if there is very good water solubility, i.e. significantly higher, i.e. provided here.
  • a neutral ammonium citrate solubility of greater than 80% and a water solubility of less than 30% is set for the phosphate content from the inorganic secondary phosphate in the fertilizer granules produced.
  • a neutral ammonium citrate solubility of greater than 90% and a water solubility of less than 15% is set for the phosphate fraction from the inorganic secondary phosphate in the fertilizer granules produced. This ratio is particularly favorable for wheat plants.
  • the type and concentration of the reactant, the way the reaction is carried out and the reaction time can also influence the type and proportion of dissolved heavy metals. For example, a higher acid strength preferably results in a higher proportion of dissolved heavy metals. A higher proportion of dissolved heavy metals is preferred in this process step, since to a large extent only the proportions that are present in dissolved form can be proportionally separated off in the heavy metal depletion process.
  • sufficient acid is therefore added to the raw material suspension so that a pH value of less than 1 is established during the incubation time.
  • a significant proportion of heavy metals is already dissolved.
  • enough acid is added to the raw material suspension that a pH value of less than 0.5 is established during the incubation time.
  • the heavy metals arsenic and lead are almost completely dissolved. If the pH value is further reduced to less than 0.2 during the incubation time, as in a particularly preferred embodiment of the invention, other heavy metals also dissolve to a greater extent.
  • At least one reactant which contains at least one of the elements nitrogen (N), sulfur (S), potassium (K) and / or phosphorus (P) includes, for example, phosphorous acid (H3P03), phosphoric acid (H3P04), nitric acid (HN03), sulfuric acid (H2S04), sulphurous acid (H2S03) and / or potassium hydroxide (KOH).
  • additional nutrient components such as nitrogen, sulfur, potassium and / or phosphorus are introduced into the granulate.
  • the nutrient binding form of the nutrients contained in the reactant for example nitrogen and / or sulfur, can preferably be converted into a form suitable for the fertilizer.
  • the reactant is a dilute or undiluted phosphoric acid and / or a phosphorous acid or at least a dilute or undiluted acid mixture with a proportion of phosphoric acid and / or phosphorous acid contained.
  • the advantage here is that the phosphorus content in the raw material suspension and thus in the fertilizer produced from it is increased by the reaction agent.
  • the reactant advantageously not only provides a valuable nutrient component, but also favors the production of phosphate fertilizers in particular.
  • fertilizer granules with a total P205 content of greater than 35%, particularly preferably greater than 40% and a phosphate content of which is neutral ammonium citrate soluble of greater than 80%, particularly preferably greater than 90%, can be produced.
  • the total content of P205 is greater than 35%, particularly preferably greater than 40%.
  • the components of the raw material suspension can be brought together in any order.
  • the reactant reacts sufficiently with at least part of the phosphate supplied by the inorganic secondary phosphate.
  • the term "react adequately" in the context of the invention means that the desired improvement in the neutral ammonium citrate solubility of the phosphate is achieved.
  • at least some of the heavy metals are preferably dissolved.
  • An incubation period in the sense of allowing the reaction agent to act is accordingly The incubation takes place over a period of time in the range from 1 to 300 minutes, preferably in the range from 5 to 100 minutes and particularly preferably in the range from 10 to 60 minutes, due to the order in which the components are brought together, the time sequence and the incubation time can, for example, have an influence on the reaction taking place and thus also on the proportion of dissolved heavy metals and the neutral ammonium citrate solubility of the phosphate in the fertilizer granules produced.
  • the incubation time is therefore set between 10 and 60 minutes, in particular to increase the ammonium citrate solubility. In a particularly preferred embodiment of the invention, the incubation time is set to 10 to 30 minutes. High ammonium citrate solubilities can also be achieved here; the shorter incubation time advantageously allows the dimensions of the reaction vessels to be reduced so that process costs can be reduced accordingly.
  • the incubation time to achieve the desired solubilities also depends, for example, on the type of reagent used. Thus, strong acids such as concentrated mineral acids or strong bases such as concentrated NaOH typically result in an accelerated reaction and a shorter incubation time is required. If, however, weaker acids, such as organic acids such as citric or oxalic acid, If used, a longer incubation period is required. In a preferred embodiment of the invention, the incubation time is set in a range between 30 and 300 minutes.
  • the incubation time is set between 60 and 300 minutes.
  • a higher process temperature preferably increases the reaction rate between the inorganic secondary phosphate and the reactant and thus shortens the incubation time required.
  • the process temperature during the incubation of the inorganic secondary phosphate and the reactant is therefore set above 30.degree. C., particularly preferably above 40.degree. C. and very particularly preferably above 50.degree.
  • the envisaged separation of the reaction for at least a partial conversion of phosphate from the inorganic secondary phosphate from the granulation preferably solves the technical problem that the exothermic, sometimes spontaneous and violent reaction greatly hinders the granulation process.
  • the separation of the reaction from the granulation provided according to the invention is preferably to be understood in the technical sense in such a way that by far the largest proportion of the reaction takes place during the preparation of the raw material suspension and the subsequent incubation period. However, it can also be preferred that the reaction continues after the incubation period, but then with a significantly reduced intensity. By adhering to the incubation time provided according to the invention, the still existing intensity of the possible progress of the reaction is no longer a hindrance to the granulation process.
  • the process is preferably controlled such that more than 80% of the increase in neutral ammonium citrate solubility of the inorganic secondary phosphate achieved over the entire process is achieved by the end of the incubation period.
  • the phosphate from the inorganic secondary phosphate treated with the reactant shows this reaction product that has been stopped in this way already at least 80% of the neutral ammonium citrate solubility of a reaction product which is not stopped, but the entire process runs through until the final fertilizer granulate.
  • the inorganic secondary phosphate added to the raw material suspension different heavy metals are typically present in different concentrations. These heavy metals are at least partially dissolved by the reaction between the inorganic secondary phosphate and the reactant.
  • the type and amount of dissolved heavy metals depends on the dissolution parameters used as described above. For reasons of sustainability, for example, it is advisable to discharge these heavy metals at least partially from the process and thus separate them from the fertilizers produced.
  • the heavy metals are at least partially separated off directly from the raw material suspension produced.
  • the heavy metals are to be separated, at least in part, directly from the raw material suspension produced, the difficulty arises that precipitation as hydroxides or sulfides alone is not effective is possible.
  • precipitation as hydroxides or sulfides alone is not effective is possible.
  • these pass from the liquid phase to the solid phase of the suspension and are thus still present in the suspension. It is true that the entire solid phase could now be separated off and discharged from the process, but in the method according to the invention the solid phase should be converted into the fertilizer granulate.
  • An electrochemical heavy metal depletion is defined by the fact that the chemical separation reactions take place with the participation of electrons that flow through an external conductor circuit.
  • a reaction partner in this electrochemical reaction is always an electrode that either accepts or releases electrons. This means that by supplying electrical energy, this chemical material conversion is carried out for the depletion of heavy metals.
  • electrochemical separation processes are to be understood as meaning all these processes which essentially cause the chemical and / or physical processes required for the cleaning operation through the action of an electrical current that is introduced into the raw material suspension to be treated via appropriately adapted electrodes.
  • the current is transported within an electrochemical reactor by ions in a mostly liquid electrolyte.
  • the raw material suspension with the dissolved components can be viewed here as an electrolyte.
  • the electrodes are basically the active components in such an electrochemical process.
  • the electrochemical reactions take place on their surfaces. In principle, they act as an electrocatalyst. They can simply consist of the catalytically active metal (full electrodes) or have a more complex structure, if z. B. acts as a substrate as a carrier of the usually expensive electrocatalyst.
  • Materials for the electrodes are, for example, metals and their alloys, carbon or graphite, electrically conductive polymers, metal oxides with a high electronic conductivity and semiconductors. Electrodes conduct the electric current and the charge carriers are electrons. They are also known as first class leaders. Depending on which electrochemical process takes place on the electrode, they are called anodes or cathodes.
  • the electrodes are the active components in the electrochemical reaction.
  • the electrochemical reactions take place on their surfaces and therefore the type and properties of the electrodes are selected according to the desired electrode reactions and the type of electrolyte.
  • the electrodes can have a wide variety of designs. For example, plate electrodes, porous electrodes, electrodes in the form of a network or so-called three-dimensional (3D) electrodes, which have a very large surface and from which to treating liquid are flowed through. Fills or porous bodies made of carbon or suitable metals can be used as 3D electrodes.
  • the device of the heavy metal depletion according to the invention can be designed, for example, as a fixed or fluidized bed cell.
  • basic reactor types are, for example, stationary stirred kettles, continuous stirred kettles, flow reactors or stirred kettle cascades.
  • the arrangement of the electrodes in relation to one another and any separators to be introduced for separating the reaction spaces are an important factor influencing the deposition process.
  • the separation system corresponds to a parallel plate reactor which is optionally equipped with separators (such as, for example, ion exchange membrane or ceramic diaphragm) for separating the reaction spaces and for preventing undesired side reactions.
  • the device for the electrochemical deposition largely corresponds to a reactor with a fixed bed cathode.
  • This embodiment offers the advantage of accommodating a large electrode area in a small space.
  • a so-called plug flow reactor can be used as the basic reactor type for continuous operation. This is ideally characterized by a uniform residence time (through-flow pipe), the conversion achieved depending on the length of the reaction space and there is no significant mixing along the flow path.
  • a cascade of homogeneously mixed stirred kettles can also be used as a reactor design, with conversion and residence time behavior converging for multi-stage cascades.
  • a so-called electrochemical metal deposition (galvanic deposition process) is used as the electrochemical process.
  • the dissolved metal ions such as heavy metal ions, are removed from raw material suspensions containing heavy metals by first converting them and depositing them on the cathode as metal and metal oxide, for example.
  • the electrolysis bath is the raw material suspension in which the heavy metals to be deposited are at least partially dissolved.
  • Electrodes which are connected to an external voltage source, are immersed in the electrolysis bath. When a direct current voltage is applied, one electrode becomes the cathode and the other becomes the anode.
  • the reaction parameters are set in such a way that the heavy metal cation is reduced at the cathode and is at least partially deposited thereon as metal or metal oxide, for example.
  • the processes taking place on the anode depend in principle on its nature. A distinction is made between soluble and insoluble or active anodes. In the case of soluble anodes, the metal of the anode can release electrons and go into solution as a positively charged ion. In a particularly preferred embodiment, an insoluble anode is used, with another oxidation process taking place to maintain the electrical circuit, for example by oxidizing the solvent, for example water, or the anions in solution.
  • Targeted setting of the electrochemical parameters such as the potential ranges for deposition (thermodynamic driving force), the achievable current densities (as an essential measure for, for example, the reaction speeds) and the selection of suitable electrodes for the deposition can influence the degree of deposition and the type of deposited elements be taken.
  • the heavy metals can be at least partially separated from the raw material suspension, for example by diverting the raw material suspension from the electrochemical reaction device or removing the cathodes after the at least partial deposition of the heavy metals on the cathode.
  • the departed Heavy metals can then be removed from the cathode, for example by flushing solutions or mechanical separation. A new cleaning process can then take place.
  • At least one complexing agent for example citric acid
  • the complexing agent serves, for example, to ensure that when the pH value increases, the dissolved heavy metals only precipitate at a higher pH value, that is to say that the precipitation range is shifted.
  • the pH range of the raw material solution can be raised, for example preferably in the range 2 to 7, and a higher proportion of heavy metals is dissolved than without a complexing agent. Raising the pH value range can promote electrochemical heavy metal depletion. For example, by increasing the pH from a very acidic range, for example in the range less than 2, it is possible to prevent the most formed metal from dissolving again.
  • the pH is set in the range 2 to 4. In this range, the dissolution of most metals can be prevented, but fewer means are required to raise the pH.
  • the electrochemical heavy metal depletion according to the invention takes place from the raw material suspension produced and can begin directly with or during the production of the raw material suspension or thereafter.
  • the electrochemical heavy metal depletion begins with the production of the raw material suspension or afterwards and runs at least temporarily in parallel during the incubation period and can go beyond the incubation period.
  • the advantage of this embodiment is that the electrochemical heavy metal depletion requires a sufficient reaction time and in this embodiment this reaction time for the electrochemical heavy metal depletion and the incubation time are at least temporarily coupled, which reduces the overall process time.
  • an incubation time is first awaited for the reaction between the inorganic secondary phosphate and the reagent and then the electrochemical heavy metal depletion is carried out. The reaction between the inorganic secondary phosphate and the reactant can also continue during the heavy metal depletion.
  • the electrochemical heavy metal depletion according to the invention can be carried out either continuously and / or discontinuously and can be in one or more stages.
  • the type and amount of the separated heavy metals result from the set process parameters of the electrochemical heavy metal depletion.
  • arsenic, cadmium, lead and / or nickel for example, should often be deposited, the amount to be deposited depending on the concentration of the contamination. In a preferred embodiment, therefore, at least 20% arsenic, cadmium, lead and / or nickel, based on the initial concentration in the inorganic secondary phosphate, are deposited from the raw material suspension. In the technical sense, this can be done relatively easily and therefore inexpensively. In another preferred embodiment, at least 40% arsenic, cadmium, lead and / or nickel based on the initial concentration are separated off. The advantage of this embodiment is that, for example, inorganic secondary phosphates with a higher heavy metal concentration can be used.
  • the electrochemical separation process in addition to the at least partial separation of heavy metals according to the invention, also depletes other pollutants.
  • organic pollutants can be caused by a suitable Process management by electrochemical reactions, for example, are broken down into at least less harmful substances.
  • the electrochemical separation process can also be used for disinfection. This is advantageous, for example, if, for example, organic structural substances are added as a further component, for which disinfection is necessary.
  • the electrochemical heavy metal depletion according to the invention results in a heavy metal depleted raw material suspension according to the invention.
  • part of the liquid phase is separated from the heavy metal-depleted raw material suspension by solid / liquid separation prior to granulation or extrusion.
  • the liquid phase separated by the solid / liquid separation is also referred to below as (separated) process water.
  • the advantage of this embodiment is that the reaction between inorganic secondary phosphate and reactant can initially take place in a raw material suspension with a higher liquid phase content with the advantages described above, but this high liquid phase content is separated mechanically with significantly less energy and not thermally by drying.
  • simple and inexpensive granulation and extrusion technologies such as granulating plates or intensive mixers can be used.
  • the amount of liquid phase to be separated in this preferred embodiment is selected according to the requirements of the subsequent granulation / extrusion. For example, the type of granulation or extrusion required determines the proportion of liquid phase to be separated.
  • At least some of the dissolved components are precipitated and / or crystallized out of the liquid phase before the solid / liquid separation.
  • This has the advantage that the process water separated by the solid / liquid separation has fewer dissolved components. This is advantageous when the process water is returned to the freezing of the raw material suspension, since this results in lower cycle concentrations of these components. This also prevents the risk of encrustation of system parts and / or pipes.
  • Such at least partial precipitation and / or crystallization can be increased, for example, by increasing the pFI value, as a result of which dissolved components precipitate, for example, as flydroxides. However, this can also be done, for example, by adding further components which, in reaction with dissolved components, form solid reaction products.
  • so much liquid phase is separated off with the solid / liquid separation that the separated moist solid can be referred to as earth-moist or an earth-moist mixture.
  • An earth-moist mixture is not a suspension according to Definition here (since the solid components in the liquid phase are not finely distributed, at least temporarily, in suspension), but can also be referred to as dispersion or raw material dispersion, since at least one solid and at least one liquid phase are still present.
  • the humidity is at least 5% to less than 40%. In other words, it is preferred in the context of the invention that the humidity is in a range between 5 and 40%.
  • the non-separated liquid phase can also contain dissolved components which remain as a solid during drying
  • the percentage of the non-separated liquid phase in this preferred earth-moist mixture is in a range between 10 and 70%.
  • the advantage of such a proportion of moisture or non-separated liquid phase is that an earth-moist mixture can be granulated or extruded directly and a relatively little liquid phase, for example in particular water, has to be evaporated to produce the particularly dry, heavy metal-depleted fertilizer granulate. This saves considerable energy costs.
  • the humidity is 10% to less than 30%. In other words, it is preferred in the context of the invention that the humidity is in a range between 5 and 30%.
  • the advantage of this embodiment of the invention is that an earth-moist mixture with this moisture content can typically be granulated directly by means of a granulating plate.
  • the partial separation of the liquid phase in the context of the present invention can be carried out continuously and / or discontinuously in one or more steps, for example by filtration or centrifugation.
  • Filtration can be carried out discontinuously, for example by means of autopress, pressure suction filters, agitated pressure suction filters, suction suction filters, plate filters, (pressure) leaf filters, bag filters, candle filters, bag filters, sheet filters, filter presses, e.g. Frame filter presses, chamber filter presses, membrane filter presses; Plate filters and / or bulk filters or continuously, for example by means of crossflow filtration, shear gap filters, tubular rotor filters, belt filters, rotary pressure filters, drum filters, rotary vacuum filters, disc pressure filters and / or sliding belt presses, without being limited to them.
  • the centrifugation can be carried out continuously by, for example, sieve centrifuges, screw sieve centrifuges, impact ring centrifuges, sliding centrifuges, pusher centrifuges, vibrating centrifuges, tumbling centrifuges and / or solid bowl centrifuges, or discontinuously, for example by pendulum centrifuges, horizontal peeling centrifuges, inverted peeler centrifuges and / or bag centrifuges, pusher centrifuges.
  • the solid-liquid separation is carried out by means of filter presses, centrifuges or vacuum belt filters.
  • the liquid phase is partially separated off with a filter press, for example a membrane filter press, in combination with mechanical pressing with dry bals of the filter cake produced.
  • a gas is preferably fed to the pressing device, which is controlled in such a way that this gas flows through the filter cake (via the pore structure) and thereby carries along adhering liquid components and thus drives them out of the filter cake.
  • the gas can in this case preferably be compressed air generated from the ambient air, wherein this compressed air can also be supplied heated. The heating also produces a drying effect.
  • the advantage of this embodiment is that it allows lower residual moisture to be achieved.
  • the heavy metal-depleted raw material suspension can be conditioned, for example to improve or simplify filtration or sedimentation.
  • flocculants or agents for adjusting the viscosity can be added.
  • the separated liquid phase (separated process water) can be discharged from the process and, for example, disposed of as waste water or fed to another use, or it can be returned and / or used in the process according to the invention itself.
  • At least part of the separated process water is fed to the production of the raw material suspension.
  • This recirculated, separated process water can preferably completely or partially replace an adequate portion of the otherwise necessary liquid phase, in particular of added water.
  • the process water can be used again directly in the process and accordingly does not have to be disposed of.
  • the separated process water can still contain a proportion of the dissolved nutrient components, for example phosphate, which are thus returned to the process.
  • at least part of the reactant for the production of the raw material suspension is fed to this separated process water after the separation by the solid / liquid separation and before the production of the raw material suspension.
  • the separated process water contains such a proportion of dissolved components that may already partially precipitate or crystallize out during the return process and cause technical difficulties, for example due to deposits.
  • the reaction agent particularly preferably acids
  • precipitation or crystallization can at least be reduced.
  • At least part of the separated process water is fed to the granulation for conditioning the raw material dispersion and / or for forming the granules, for example by spraying onto the raw material dispersion on the granulating plate. Feeding of further components to the raw material suspension
  • Further components can be added to the raw material suspension / dispersion before, during or after the incubation period, before during or after the heavy metal depletion and / or before or during the granulation or extrusion.
  • Further components are generally those substances that can improve the process control and / or the properties of the fertilizer granulates, for example nutrient-containing components, dispersants and defoamers, structural substances, pH adjustment agents, urease inhibitors, ammonium stabilizers, humic acid, organic Acids and / or water.
  • nutrient-containing components are preferably substances that supply or supplement the nutrient supply for the cultivated plants in order to control or support the growth and development of the plants.
  • the nutrient-containing components include nitrogen (N), phosphate (P), potassium (K), magnesium (Mg), sulfur (S), essential trace elements individually or in combination.
  • N nitrogen
  • P phosphate
  • K potassium
  • Mg magnesium
  • S sulfur
  • essential trace elements individually or in combination.
  • the nutrient composition in the fertilizer granulate can be adapted particularly precisely to the needs of the soil and / or plants.
  • the typical fluctuation range of the composition of the inorganic secondary phosphate can be compensated for in order to ensure a uniform fertilizer quality.
  • additional phosphate carriers for example ammonium phosphate, potassium phosphate, crystallization products from phosphorus elimination, such as struvite, brushite or hydroxylapatite-like Ca-P phase, are added in such an amount that a fertilizer granulate with a total P205 Content of greater than 35%, particularly preferably greater than 40% and a neutral ammonium citrate-soluble phosphate fraction thereof of greater than 80%, particularly preferably greater than 90%.
  • crystallization products from phosphorus elimination such as struvite, brushite or hydroxylapatite-like Ca-P phase
  • crystallization products from phosphorus elimination are added in a range from 1 to 70%, based on the finished pedosphere-improving granules, so that nutrient granules with a Total P205 content of more than 15%, a neutral ammonium citrate-soluble phosphate content of more than 60% thereof and a water solubility of less than 30%, also based on the total P205 content.
  • crystallization products from phosphorus elimination in the range of 10 to 40%, based on the finished pedosphere-improving granules are added, nutrient granules with a total P205 content of greater than 15%, with a neutral ammonium citrate-soluble phosphate content thereof , based on total P205, of greater than 85% and a water-soluble phosphate content, based on total P205), of less than 20%, based on the composition of the nutrient granules.
  • One or more structural substance (s) can be used as further components, for example peat, humus, pyrolysis substrates from biomass, biochar from hydrothermal sources Carbonization (HTC), but also sewage sludge, digestate, liquid manure, animal excrement, animal and / or fish meal.
  • the term “digestate” describes in the context of the invention the liquid and / or solid residue that remains during the fermentation of biomass.
  • the term “liquid manure” preferably describes a mixture of manure and urine from farm animals in combination with Litter with changing water content.
  • the fertilizing effect can be adjusted and / or a soil-improving effect can be achieved when using the fertilizer granules.
  • the fertilizing effect is preferably influenced by the fact that the structural properties of the fertilizer granulate produced and thus its properties, such as the porosity, size of the pores, strength and / or solubility, can be adjusted by adding the structural substance.
  • the nutrient release can be specifically adapted to the plant growth and the time-dependent nutrient requirement of the plant.
  • Targeted soil improvement can also be achieved by adding a structural substance to the fertilizer granulate if the structural substance is used, for example, to form humus, to improve the soil structure and / or to improve the air and / or water balance of the soil when using the Fertilizers in agriculture leads. This can, for example, promote root growth, activate soil life and / or stimulate plant vitality against stressful situations.
  • a total of between 5 to 50% structure substance based on the finished pedosphere-improving granulate is added, since it was surprisingly found that in this concentration range, in particular, the formation of humus is very strongly promoted and therefore particularly good soil and soil Structural improvement is effected. It is very particularly preferred that the granules formed have a carbon content of greater than 5 to 25%, since it was unexpectedly found that in this area of the carbon content, in addition to the formation of humus, the air and water balance of the soil in particular is particularly favorable for the growth of for example winter barley and corn can be adjusted.
  • the fertilizing effect is preferably influenced by the fact that the structural properties of the generated pedosphere-improving granulate and thus its properties, such as the porosity, size of the pores, strength or solubility, are set by adding the structural substance.
  • the nutrient release can be specifically adapted to the plant growth and the time-dependent nutrient requirement of the plant. Therefore, in another preferred embodiment of the invention, between 0.1% to 5% structural substance is added.
  • a particularly large number of nutrient components can be integrated in the fertilizer, whereby the fertilizing effect of the granules in this exemplary embodiment is fundamentally reinforced.
  • a sanitation step is used Interruption of infection cycles by killing pathogens, bacteria etc. integrated into the proposed method.
  • Methods such as adding chemical or bacteria-killing agents, hygienizing through an extreme pH shift, for example by adding quick lime or hydrated lime, or thermal treatment are available for sanitation.
  • Such a process step for sanitizing the critical residue (s) can be carried out at a suitable point in the process.
  • Such a sanitization of the residues can take place before the addition of the residues as structural material to the raw material suspension / dispersion.
  • a residual material such as sewage sludge
  • the sanitization takes place by a thermal treatment of at least 10 minutes, preferably longer than 20 minutes and above 60 ° C, particularly preferably above 75 ° C. This temperature action advantageously largely kills the pathogens.
  • the thermal treatment of the critical residues can take place, for example, in process step a) and / or d), for example by heating the raw material suspension / dispersion or heating itself up through exothermic reactions.
  • humic acid and / or fulvic acid and / or salts thereof are added.
  • These substances advantageously have growth-promoting properties. This significantly increases the nutrient absorption capacity of the roots and thus stimulates growth. Their addition promotes plant growth and cell formation. They stimulate the cell membranes as well as the metabolic activities and thereby increase the germination rate. Important plant enzymes are also particularly well stimulated.
  • the strong root formation supports the nutrient absorption capacity. The plants strengthened in this way are significantly less susceptible to disease.
  • the addition of these substances can increase the plants' P uptake, as it blocks the P adsorption in the soil and, by complexing Ca, Al, Fe, prevents P from precipitating into poorly soluble compounds.
  • organic acids are added in solid and / or liquid form.
  • Organic acids are, for example, ascorbic acid, acetic acid, formic acid, gluconic acid, malic acid, succinic acid, oxalic acid, tartaric acid and citric acid.
  • Organic acids play an essential role in the absorption of phosphate by plants from the soil.
  • the presence of organic acids on the roots means that the plants can absorb sufficient phosphate, whereby microorganisms typically form these organic acids in the ecosystem.
  • one or more organic acids are preferably integrated in total in a range from 0.1 to 30% (based on the finished pedosphere-improving granules). It is presumed that these, along with the organic acids that are fed in, preferably take on a comparable function in the root area of the plant without these organic acids first having to be generated by microorganisms. Citric acid, oxalic acid and / or tartaric acid are preferably used individually or in combination, since these organic acids are relatively inexpensive and available in sufficient quantities.
  • citric acid, oxalic acid and tartaric acid individually or in combination in a quantity range 0.1% to 10% (based on the finished pedosphere-improving granules) is particularly preferred, since the absorption-improving effect of these acids is particularly favorable in relation to the raw material costs.
  • the listed proportions of organic acids in the fertilizer granulate can either be added as an additional component and / or, if organic acids are used as reactants, after the reaction (at least proportionally further in this quantity range) and thus transferred to the fertilizer granulate.
  • Defoaming agents and dispersants can also be added as additional components. Defoaming agents are advantageous, for example, when a strong gas-forming reaction sets in or a foam forms when individual substances are brought together, for example when producing the basic dispersion. The viscosity can, for example, be adjusted by the dispersant.
  • the pH of the heavy metal-depleted raw material suspension / dispersion is set in the range between 4 and 11 after the heavy metal separation or the earth-moist mixture before or during the granulation or extrusion. In this way, for example, remaining acid residues, for example when using acids, can be neutralized.
  • the pH of the heavy metal-depleted raw material suspension / dispersion or the earth-moist mixture is set in the range between 6 to 8 before or during the granulation or extrusion. This results in fertilizers that are depleted of heavy metals and whose pH value is largely neutral.
  • the substances used can be added individually or in combination or the entire raw material suspension / dispersion can be ground. This is advantageous, for example, if the existing particle or aggregate size of individual or several starting materials is not sufficiently fine enough to achieve sufficient homogeneity, for example, or this can lead to process-related difficulties, for example clogging of nozzles. This can advantageously be improved by reducing the particle or aggregate size.
  • the solubility of substances or the compounds they contain can also be improved, for example the solubility of phosphate-containing ashes or slags.
  • the aggregates used for dry or wet milling can be, for example, ball mills, pin mills, jet mills, bead mills, agitator ball mills, high-performance dispersers and / or high-pressure homogenizers.
  • the order in which the further components are added can be carried out depending on the requirements of the process management and / or the possibly desired reaction sequence. All other components can be added together or sequentially at one point in the process, for example after the incubation period before the heavy metal depletion. The other components can also be added at various points in the process.
  • the addition can be added to the dispersion already produced from at least one inorganic secondary raw material and at least one reactant and / or also during the production of this dispersion. It is also preferred that all or some of the further components are initially taken and only for this purpose the dispersion of at least one inorganic secondary phosphate and at least one reactant or the components for forming this dispersion is added.
  • all or some of the further components are added after the heavy metal depletion.
  • the other components initially do not affect the reaction between the inorganic secondary phosphate and the reactant.
  • these additional components also do not influence the heavy metal depletion and simplify the heavy metal depletion.
  • further components can be added when the raw material suspension / dispersion is transferred from the heavy metal depletion facility to a mixer.
  • the mixing device can be, for example, a mixing container with agitator, roller mixer, which is preferably also referred to as a falling, drum or rotary mixer, shear mixer, compulsory mixer, ploughshare mixer, planetary mixer, Z mixer, Sigma mixer, fluid mixer or intensive mixer.
  • the selection of the suitable mixer depends in particular on the flowability and the cohesive forces of the material to be mixed.
  • the raw material suspension according to the invention is first produced, the electrochemical heavy metal depletion and then a solid / liquid separation carried out.
  • the moist solid separated in the solid / liquid separation is then placed in a mill-drying unit.
  • the desired composition in particular the nutrient composition of the raw material dispersion, is set by adding further components to the moist solid after the solid / liquid separation and / or in the mill-drying unit.
  • the moist solid is ground together with the other components and at the same time the moisture is reduced to such an extent that the resulting mixture has a residual moisture that is suitable for the subsequent granulation process.
  • the advantage of this embodiment is that on the one hand the filter cake is deagglomerated by the grinding.
  • the heavy metal-depleted raw material suspension / dispersion is converted into a heavy-metal-depleted fertilizer granulate by granulation or extrusion.
  • the granulation or extrusion can preferably take place during the admixing of further components and / or afterwards, for example in the same mixer or in a separate granulating or extrusion unit, which is formed for example by pelletizing or granulating plates, granulating drums, fluidized bed granulators, spray granulators or extruders .
  • the proportion of the liquid phase or the moisture content of the heavy metal-depleted raw material suspension / dispersion has a significant influence on the reactions taking place, the type of granulation, the product quality and / or the economic viability of the process.
  • the total proportion of the liquid phase or the moisture before the granulation and / or extrusion can be, for example, via the process control of the preceding steps, optionally a partial separation of the liquid phase by a solid / liquid separation and the type and amount of the liquid, moist or dry components. If necessary, partial drying can also take place before granulation, for example in order to adjust the total proportion of the liquid phase before granulation and / or extrusion.
  • the raw material dispersion is or will be adjusted before the granulation / extrusion so that it contains a moisture content of less than 30%, preferably less than 25% and particularly preferably less than 20% and thus corresponds to an earth-moist mixture.
  • the preferably earth-moist mixture can preferably be granulated and / or extruded directly.
  • relatively inexpensive granulation and / or extrusion processes or technologies such as roller mixers, shear mixers, ploughshare mixers, planetary mixing kneaders, intensive mixers and / or extrusion processes, can be used.
  • the tendency to stick required for granulation can preferably also be adjusted by different substances, such as binders. These can, for example, also be added.
  • the advantage of this preferred embodiment of the invention is that a good roundness of the granules is achieved in the preferred granule size range and the granulation technology and the process costs can be used inexpensively.
  • the heavy metal depleted raw material dispersion thus reduced in the liquid phase portion is then optionally further components in an intensive mixer, for example an intensive mixer type R Fa. Eirich, where the liquid phase content is preferably set and, if necessary, binder added so that the intensive mechanical mixing results in green granules with a desired grain size, preferably in a range from 1 to 10 mm, particularly preferably from 2 to 5 mm .
  • green granules comprise at least all components of the fertilizer granules, the green granules preferably having a liquid phase portion, which is also referred to as "moisture” in the context of the invention, this liquid phase portion preferably being able to be removed by drying.
  • the granulation takes place on a pelletizing or granulating plate.
  • the heavy metal depleted raw material dispersion reduced in the liquid phase portion is then fed to a pelletizing or granulating plate with additional components if necessary.
  • a liquid component preferably in combination with a binder contained therein or separately supplied, is sprayed onto the raw material dispersion on the granulating plate.
  • the liquid component is water.
  • the supplied raw material dispersion is adjusted in terms of moisture content or the proportion of the liquid phase in advance so that the green granules that are formed during and / or after the granulation are advantageously formed by adding the liquid component and the rotating movement of the pelletizing or granulating plate the fertilizer granules can be dried.
  • the advantage of this embodiment of the invention is that the granulation and the necessary technology are particularly inexpensive. In addition, this simple granulation technology is less susceptible to repair.
  • the raw material suspension / dispersion is or will be adjusted before the granulation in such a way that the proportion of the liquid phase is greater than 25%, preferably greater than 35%.
  • the granulation of the pollutant-depleted raw material suspension takes place in a fluidized bed or spouted bed reactor, particularly preferably by spray granulation or spray agglomeration. Apparatuses of this type are known to the person skilled in the art and are offered, for example, by Glatt with the AGT or GF series. For this purpose, the pollutant-depleted raw material suspension including any additional components is fed to a fluidized bed reactor.
  • the additional components can be, for example, nutrient-containing components, dispersants and defoamers, agents for adjusting the pFI value and / or water, which can be added individually or in combination beforehand.
  • the feed takes place by spraying, for example by spraying through nozzles.
  • the raw material suspension is pumpable and sprayable. This can preferably be achieved in that, for example, the proportion of liquid phase is sufficiently high, for example in that correspondingly necessary amounts of preferably water are supplied. Flea quantities of the liquid phase favor the stability and the pumpability of the raw material suspension and thus simplify the technical operation.
  • the fertilizer granules to be produced should have a low proportion of liquid phase or a moisture content that is preferably less than 5%, particularly preferably less than 2%, it is preferred in the context of the invention that the liquid phase, for example during granulation in this embodiment is removed. It is therefore particularly preferred to adjust the liquid phase in the raw material suspension in the fleas, so that 40-70% fertilizer granules form from the pollutant-depleted raw material suspension, very particularly preferably 45-60%.
  • a formation of 40-70% fertilizer granulate from the raw material suspension corresponds in the context of the present invention to a solids content in a range from 40 to 70% or between 40 and 70%.
  • a pollutant-depleted raw material suspension can advantageously be made sufficiently stable and pumpable, whereby the energetic expenditure for the separation of the liquid phase is to be assessed as acceptable, especially in comparison to conventional methods known from the prior art.
  • the raw material suspension can be frozen in a stirred tank or mixer.
  • the advantage of this preferred embodiment for granulation is that the granulate size can be adjusted particularly well, the granulates are very homogeneous and a particularly round and compact granulate shape is achieved.
  • the granules obtained are particularly easy to handle and particularly easy to apply to fields, for example with spreading devices.
  • the compactness of the granules results in little dust and abrasion, which is also advantageous for spreading using, for example, spreading devices. Drying / fractionation of the heavy metal-depleted fertilizer granules produced
  • the pollutant-depleted fertilizer granules have a low level of moisture, i.e. physically bound water.
  • a humidity is in a range of less than 5%, preferably less than 2%.
  • such a moisture range can already be achieved during the granulation, in particular during the spray agglomeration or granulation in which the granulation and / or drying take place largely simultaneously.
  • the generated granules depleted of harmful substances are dried or at least additionally post-dried after the granulation and / or extrusion.
  • Various drying technologies are available for this, such as contact dryers, in which the thermal energy required for drying is preferably supplied through contact with meat surfaces, convective dryers, in which the thermal energy required for drying is preferably supplied through contact with industrial gas, or radiation dryers, in which the thermal energy required for drying is preferably supplied by radiation with a defined frequency.
  • the existing liquid phase for example the water, is separated off to the required extent by the drying.
  • the drying also preferably results in an increase in the strength of the granules, for example in that binding phases form as a result of the drying or, for example, in that a binder develops its binding effect as a result.
  • the drying takes place through the inherent heat of the granulates produced or is at least supported by it.
  • the granules receive their own heat preferably through heating.
  • the granules can be heated by the granulation and / or extrusion process or by chemical reaction as a result of the process. If the granules are heated by the granulation and / or extrusion process, it is preferred in the context of the invention that the heating takes place by introducing mechanical energy, the mechanical energy preferably being converted into thermal energy.
  • reaction between CaO and acid and / or water or the reaction between sulfuric acid and water, especially during dilution, provide exothermic energy, which can preferably be used to heat the raw material dispersion and / or the shaped granules.
  • crystallization products from phosphorus elimination such as struvite, brushite and / or hydroxylapatite-like Ca-P phase
  • the drying is carried out in one preferred embodiment of the invention takes place above 100 ° C based on the material temperature during drying.
  • These crystallization products preferably contain a large proportion of chemically bound water, which is preferably not "moisture” within the meaning of the invention, but rather water that is bound in the crystal structure. In the range above 100 ° C., this chemically bound water becomes By separating the water from the granules, the percentage of the remaining components is advantageously increased.
  • the concentration of nutrients in the granules can be increased that were previously diluted by the chemically bound water.
  • drying takes place when crystallization products from phosphorus elimination are contained in a range of 100-140 ° C. based on the material temperature during drying. It is therefore very particularly preferred in the context of the invention that drying is carried out in a temperature range between chen 100 and 140 ° C takes place. Above 140 ° C there is a risk that nitrogen will increasingly be split off. This is associated with an undesirable loss of nitrogen from the granulate. In addition, the exhaust air has to be cleaned in a correspondingly more complex manner. By limiting to a temperature of max. 140 ° C. in this preferred embodiment of the invention, these disadvantages can largely be avoided. In a very special embodiment of the invention, drying takes place in a temperature range between 120.degree. C. and 140.degree.
  • the pollutant-depleted fertilizer granules can be produced with as precise a shape as possible.
  • a size of the granules that is as uniform as possible advantageously ensures defined, uniform disintegration properties, which is necessary for a targeted supply of nutrients. Since the presence of oversized and undersized grains can impair the machine application of the fertilizer, it is preferred in the context of the invention that oversized and undersized grains are separated from the good grain and, if necessary, from the production process, in particular before or during the mixing and / or Granulation process, if necessary with previous processing and / or grinding, can be recycled.
  • the term "good grain” preferably describes a granulate in a desired size range for the granulate grains.
  • a good grain in the range 1 to 10 mm, particularly preferably 2-5 mm.
  • granulates can typically
  • oversize grain and undersize grain in the context of the invention preferably describe those granules which - preferably significantly - have larger or smaller diameters than the good grain.
  • the heavy metal-depleted granulate has a good bond within the granulate in order to avoid dust losses when applying the fertilizer even after prolonged storage.
  • the strength of the granules can be adjusted, for example, via the process control.
  • the drying speed has an influence on the porosity and compactness and thus on the strength of the granules and can be influenced by this.
  • the strength can also be influenced, for example, by the type and fineness of the raw material components or increased by adding binding agents.
  • the heavy-metal-depleted fertilizer granulates produced according to the invention can receive one or more coatings for functionalization (e.g. reducing the tendency to clump, increasing strength), for protection (e.g. against moisture) and / or for controlled release of nutrients (influencing solubility by the coating).
  • coatings for functionalization e.g. reducing the tendency to clump, increasing strength
  • protection e.g. against moisture
  • / or for controlled release of nutrients influencing solubility by the coating.
  • Numerous methods and technologies for coating are known to the person skilled in the art, all methods and technologies which produce a desired coating with the desired functionality being suitable here.
  • the process steps of the method according to the invention are carried out as described.
  • the individual process steps can be designed as batch and / or continuous processes, with buffer containers being able to be used between the process steps.
  • a single unit and / or, in particular to map larger production quantities several identical or similar units can be used.
  • Several units in one or more process steps can be connected in parallel and / or alternately.
  • the process steps run in batches and / or continuously, for example, until the desired production amount is reached. Generation and use of N / P connections
  • At least one N / P compound from an upstream precipitation and / or crystallization process is added to the process according to the invention for the production of heavy metal-depleted fertilizer granules as a further component of the raw material mixture, the heavy metal-depleted raw material mixture and / or the moist solid.
  • the starting material for this precipitation process is at least one nitrogen and sulfur-containing, particularly preferably an ammonium and sulfate-containing starting solution or starting suspension.
  • nitrogen and sulfur-containing solutions or suspensions occur, for example, in washers for exhaust gas purification or in the production of biogas.
  • concentration of nitrogen or ammonium and sulfur or sulfate can be any.
  • further components can be present in dissolved form.
  • nitrogen- and sulfur-containing solutions or suspensions in the process according to the invention for producing fertilizers with a low level of heavy metals is basically possible without pretreatment.
  • these solutions or suspensions can, for example, be used in the production of the raw material suspension according to the invention and, for example, replace water otherwise supplied in an adequate amount.
  • the useful use, i.e. the possible amount added, of such untreated solutions and suspensions is limited. If more nutrients such as N and S are to be used from such solutions / suspensions, for example as an inexpensive source of nutrients, such a nitrogen and sulfur-containing solution or suspension could e.g. be concentrated by (partially) thermal drying. However, thermal drying is energy-intensive and therefore expensive.
  • the method proposed here for at least partial separation of the nutrients from the solution / suspension offers a possibility of using the nutrients of such nitrogen- and sulfur-containing solutions or suspensions to a greater extent more economically.
  • the proposed precipitation or crystallization and subsequent separation can be used, for example, as an upstream or supplementary process step, and the illustrated subsequent use of these nutrients / precipitation products for the production of the fertilizer granules can be advantageous.
  • the nitrogen or the ammonium should be at least partially precipitated or crystallized from the at least one nitrogen- and sulfur-containing solution / suspension as at least one nitrogen-phosphate-containing compound.
  • Numerous phases can be considered as nitrogen-phosphate-containing compounds, some of which are also completely miscible in the crystallographic sense.
  • N-phosphates such as (NH4) 2HP04, NH4H2P04
  • Mg-N-phosphates such as MgNH4P04 * 6 H20 (struvite), MgHP04 * 3 H20, Mg3 (NH4) 2 (HP04) are preferred for the purposes of the invention. 4 * 8 H20, Mg (NH4) 2 (HP04) 2 * 4 H20), KN phosphates.
  • At least one solution / suspension containing ammonium and sulfate is supplied with at least one P compound as a precipitation reagent, for example phosphoric acid or a phosphorus salt.
  • a precipitation reagent for example phosphoric acid or a phosphorus salt.
  • Mg-N-phosphates are to be precipitated or crystallized, at least one Mg compound is added as a precipitation reagent such as MgO, Mg (OH) 2 or Mg salts or is present in the solution / suspension in sufficient quantity.
  • K-N-phosphates are to be formed, at least one K compound, for example KOH or K salts, is added as a precipitation reagent or is present in the solution / suspension in sufficient quantity.
  • the amount of P added and, in the particular embodiments, K and / or Mg in the ammonium- and sulfate-containing solution is adjusted so that the desired type and amount of the precipitation and / or crystallization products can be formed stoichiometrically (adjustment of the stoichiometry).
  • the setting of the stoichiometry can also take place superstoichiometrically, that is to say a larger amount of one or more components is added than would be stoichiometrically required to form the target phase. In this way, for example, the reaction and / or dissolution equilibrium can be shifted in favor of a preferred phase. For example, a lower concentration of dissolved nitrogen or ammonia can be achieved.
  • the required P, Mg and K compounds can be added separately or together.
  • the pH of the ammonium- and sulfate-containing solution is adjusted so that precipitation and / or crystallization of the desired phases can take place to the desired extent.
  • This area is often referred to as the precipitation area.
  • the pH is set in the range from 6 to 11, particularly preferably 8 to 10.
  • the pH adjustment of the precipitation conditions can take place before, with or after the adjustment of the stoichiometry.
  • the ammonium and sulfate-containing solution / suspension can also be conditioned before and / or during the precipitation and / or crystallization process. For example, complexing agents, precipitants or dispersants can be added.
  • the sulfur or the sulfate should likewise be at least partially precipitated or crystallized from this at least one nitrogen- and sulfur-containing solution / suspension as at least one sulfate-containing compound.
  • Suitable sulfur-containing compounds are, for example, alkali and / or alkaline earth sulfates, with alkalis or alkaline earths being added as the precipitation reagent.
  • the sulfate is precipitated or crystallized out at least partially as calcium sulfates from the at least one nitrogen- and sulfur-containing solution / suspension.
  • at least one Ca compound is added as a precipitation reagent, for example as Ca (OH) or CaO, to at least one solution containing ammonium and sulphate.
  • the amount of Ca added is adjusted so that the desired type and amount of Ca sulfate can form stoichiometrically.
  • the stoichiometry can be set superstoichiometrically, that is to say a larger amount of one or more components is added than would be stoichiometrically required to form the target phase. For example, a lower concentration of dissolved calcium or sulfate can be achieved here.
  • the separation according to the invention of sulfate from nitrogen- and sulfur-containing solutions / suspensions can take place before, simultaneously with or after the separation according to the invention of the nitrogen or ammonium. This was based, for example, on the type and conditioning of the nitrogen- and sulfur-containing solution / suspension or the type and amount of the desired reaction products. For example, if the precipitation and / or crystallization conditions, such as the pH range required for the separation of the nitrogen or ammonium on the one hand, differ from the suitable conditions for the separation of the sulfate, separate precipitation is advisable, for example.
  • suitable conditions are first set in the solution / suspension for the precipitation and / or crystallization of nitrogen or ammonium and then for sulfate or vice versa, with the precipitates and / or crystallization products formed being able to be separated off in between.
  • This preferred embodiment can therefore also be advantageous if two separate precipitation and / or crystallization products are to result.
  • the sulfate is first separated from the nitrogen- and sulfur-containing solution / suspension as described and only then is the nitrogen or ammonium separated from the solution. This is particularly advantageous when the nitrogen and sulfur-containing solution is acidic. Ca sulfates can already be precipitated and / or crystallized out in the sometimes very acidic range (pH value less than 3).
  • the sulfate is largely precipitated and / or crystallized out together with the N / P phase.
  • a sufficient reaction time is required for the separate or joint precipitation and / or crystallization reactions. This reaction is typically in the range between 1 and 300 minutes. A reaction time between 5 and 100 minutes is preferred, since experience has shown that a quantitative reaction takes place on a sufficient technical scale, a longer residence time increases the proportion of precipitation product somewhat, but also makes it necessary to dimension the equipment. In a particularly preferred embodiment, the reaction time is set in the range between 5 to 30 minutes, since sufficient quantitative precipitation and / or crystallization still takes place here, but the equipment can be made particularly small.
  • the precipitation and / or crystallization products can be separated between individual precipitation and / or crystallization stages and discharged from the solution / suspension in order to obtain, for example, qualitatively separated precipitation and / or crystallization products. Separation and discharge can also take place during the precipitation and / or crystallization reaction in order, for example, to shift the solution equilibria in a preferred direction.
  • the extent of the desired precipitation of the dissolved nitrogen and sulfur compounds and the type of precipitation products depend on the technical requirements of the process and the desired quality of the precipitation and / or crystallization compounds, and precipitation and / or crystallization does not have to be complete. According to the invention, however, at least 60% of the dissolved nitrogen and sulfate content should be precipitated and / or crystallized out of the solution / suspension. Precipitation and / or crystallization of the dissolved nitrogen and sulfate of more than 90% is preferred, since the process is then particularly economical.
  • the nitrogen and / or sulfur content is precipitated and / or crystallized out of the solution / suspension at least to such an extent that only such a low concentration of nitrogen and sulfur remains in the solution / suspension that after separation of the Solution of the precipitation and / or crystallization products, this solution can be used, for example, as service water.
  • precipitation and / or crystallization is set to such an extent that a concentration of nitrogen still present in dissolved form of less than 1 g / l and of dissolved sulfur present in less than 10 g / l. If the solution is then to be discharged as waste water, for example, much lower concentrations must often be achieved. For this reason, in a very special embodiment, the concentration of nitrogen still present in dissolved form is set to less than 100 mg / l and of sulfur present in dissolved form is set to less than 1 g / l.
  • At least one additional separation stage for at least dissolved nitrogen or ammonium and dissolved sulfur or sulfate can be performed after the precipitation and / or crystallization or other undesirable substances.
  • the solution / suspension is brought into connection with an adsorbent and / or absorbent.
  • adsorbent and / or absorbent for example, such a means as a powder or Granules are mixed into the solution / suspension or the solution can be passed over or through a bed with such means.
  • part of the dissolved nitrogen / ammonia or sulfur / sulfate is at least partially bound to or in the adsorbent and / or absorbent and is thus removed from the solution.
  • the solution and the adsorbent and / or absorbent are then separated. It can be advantageous for the solution / suspension to be conditioned before or during contact with the adsorbent and / or absorbent. For example, reducing or oxidizing substances can be added to change the nature of the dissolved elements or compounds, or a suitable pH value can be set.
  • This combined or separate precipitation and / or crystallization process of sulfate and nitrogen or ammonium from the nitrogen and sulfur-containing starting solution / suspension results in precipitation and / or crystallization products which can differ depending on the composition of the starting solution / suspension and the process management.
  • sulfate-containing and N- / P-containing precipitation and / or crystallization processes that are present separately from one another result.
  • the sulfate phase was precipitated or crystallized out separately from the N / P phase.
  • foreign components can also be precipitated or crystallized out.
  • the other precipitation and / or crystallization product contains only a proportion of less than 10% based on the concentration ratios in the starting solution.
  • the at least one sulfate phase produced and the at least one N / P phase produced are mixed together in an end product. This results when sulfate and nitrogen or ammonium are largely precipitated simultaneously or the precipitation and / or crystallization products are not separated off between separate precipitation and / or crystallization steps.
  • such a starting solution is used and the process is controlled in such a way that a mixture with 2 to 8% N, 5 to 15% P and 5 to 10% each of Mg, S and Ca results from the process (analytically determined on a mixture sample dried at 80 ° C).
  • the P is present as a phosphate and, in a preferred embodiment, is more than 80% neutral ammonium citrate soluble.
  • such a starting solution is used and the process is controlled in such a way that a mixture with 2 to 8% N and 5 to 15% P, Mg, S and Ca results from the process (analytically determined on one at 80 ° C dried mixture sample).
  • the P is present as a phosphate and in a preferred embodiment is more than 80% neutral ammonium citrate soluble.
  • the precipitation process according to the invention can be carried out either continuously and / or discontinuously and can be in one or more stages.
  • resulting precipitation and / or crystallization products can be conditioned further. For example, drying and / or granulation can take place. Further components can also be added, for example for nutrient enrichment. Granulates can be coated to make them more abrasion-resistant or hygroscopic, for example.
  • these resulting precipitation and / or crystallization products are at least proportionate to the process according to the invention for the production of heavy metal-depleted fertilizer granules as a further component of the raw material mixture, the heavy-metal-depleted raw material mixture and / or the moist solid admitted.
  • the process for generating the precipitation and / or crystallization products can be temporally, spatially and technically separate from the process for the production of heavy metal-depleted fertilizer granulates, for example in two separately operating plants.
  • the process for producing the precipitation and / or crystallization products is procedurally and / or process-technically coupled with the process for the production of fertilizer granules that have been depleted of heavy metals.
  • the precipitation and / or crystallization products produced are at least partially fed to another utilization, for example (conventional) fertilizer production or direct use as fertilizer.
  • another utilization for example (conventional) fertilizer production or direct use as fertilizer.
  • the process for generating the precipitation and / or crystallization products is temporally, spatially and technically separate from the process for the production of heavy metal-depleted fertilizer granules, for example in two separate plants.
  • FIG. 1 describes the basic embodiment of the method according to the invention for producing fertilizers from inorganic secondary phosphate.
  • heavy metals are already depleted according to the invention and thus a heavy metal-depleted fertilizer granulate 7 is produced.
  • a raw material suspension 3 is first produced from at least one inorganic secondary phosphate 1 and at least one reactant 2.
  • the raw material suspension produced has a liquid phase content of greater than 45%.
  • This high proportion of liquid phase set in this way basically serves as a buffer for the ongoing reaction between the inorganic secondary phosphate and the reactant, which often takes place spontaneously and in some cases very exothermically and is thus controllable and controllable and the stickiness of the mixture is also greatly reduced.
  • the reactant 2 should react with at least parts of the phosphate introduced by the inorganic secondary phosphate 1 in order to thereby increase the solubility and availability of this phosphate to plants. Only after the reaction between the inorganic secondary phosphate and the reactant has largely taken place is further processing up to the granulate. The reaction of the
  • phosphate conversion is thus separated from the granulation process.
  • heavy metals are then depleted from the raw material suspension produced in this way and discharged from the process of producing fertilizer granules as a separated pollutant 4. In a preferred embodiment, this takes place by means of one or more electrochemical processes.
  • the inventive heavy metal-depleted raw material suspension 5 is formed by the depletion of heavy metals according to the invention. Then the
  • the raw material suspension can also contain further components 6 (for example nutrient-containing components, dispersants and defoaming agents, structural substances, agents for pH adjustment, Urease inhibitors, ammonium stabilizers) can be added either during the production of the raw material suspension itself, after the incubation period, after the heavy metal depletion and / or during granulation / extrusion.
  • further components 6 for example nutrient-containing components, dispersants and defoaming agents, structural substances, agents for pH adjustment, Urease inhibitors, ammonium stabilizers
  • This granulation / extrusion process step results in soil- and plant-specific fertilizer granules 7 with a set and constant nutrient composition, with inorganic secondary phosphate (such as sewage sludge ash) being used as at least one source of nutrients, the phosphate contained therein being made more readily available to plants through the action of the reactant and the Heavy metals contained in the inorganic secondary phosphate were at least partially separated.
  • inorganic secondary phosphate such as sewage sludge ash
  • the granulate / extrudate produced can be dried and fractionated.
  • the granulates / extrudates produced can also be coated with one or more coatings of the further components 6 before, during, between or after drying and / or fractionation.
  • FIG. 2 likewise describes the basic embodiment of the method according to the invention.
  • the difference to the embodiment according to FIG. 1 is that the electrochemical heavy metal depletion takes place at least temporarily parallel to the incubation time. After the preparation of the raw material suspension according to the invention, the incubation time between the inorganic secondary phosphate and the reagent begins. In this embodiment, the electrochemical heavy metal depletion takes place at a time or offset. The electrochemical heavy metal depletion can be ended before, with or after the incubation period.
  • FIG. 2 corresponds to the description of FIG. 1.
  • FIG. 3 shows a preferred embodiment of the method in which, after the heavy metal depletion, part of the process water is separated from the raw material suspension.
  • the advantage of a partial (mechanical) separation of process water is that it is considerably less costly and energy-intensive than thermal separation, for example by evaporation.
  • a raw material suspension is initially produced analogously to FIG. 1, the necessary incubation time is observed and the electrochemical heavy metal depletion according to the invention is carried out.
  • the electrochemical heavy metal depletion can also take place at least temporarily in parallel with the incubation period.
  • Part of the process water is separated by solid / liquid separation after heavy metal depletion and before granulation / extrusion.
  • the separated process water 9, which has already been depleted of heavy metals, can, for example, be discharged from the process and / or supplied before granulation for conditioning the raw material suspension or for granulation to shape the granules.
  • a preferred embodiment is that at least a portion of this separated process water is returned to the production of the raw material suspension.
  • the moist solid 8 resulting from the solid / liquid separation is fed to granulation / extrusion.
  • the raw material suspension / dispersion can also contain additional components 6 (for example nutrient-containing components, dispersants and defoaming agents, structural substances, agents for pH adjustment, urease inhibitors, ammonium stabilizers) either during manufacture to the raw material suspension / dispersion itself, after the incubation period, after heavy metal depletion and / or during granulation / extrusion.
  • additional components 6 for example nutrient-containing components, dispersants and defoaming agents, structural substances, agents for pH adjustment, urease inhibitors, ammonium stabilizers
  • At least part of the reactant 2 can be added to the separated and heavy metal-depleted process water 9 for the next filling of the raw material suspension. This proportion of reactant 2 then arrives with the heavy metal-depleted process water 9 to freeze the raw material suspension.
  • the granulation / extrusion process step results in soil and plant-specific fertilizer granulates 7 with a set and constant nutrient composition, with inorganic secondary phosphate (such as sewage sludge ash) being used as at least one source of nutrients, with the phosphate contained therein acting through of the reagent was made more readily available to plants and the heavy metals contained in the inorganic secondary phosphate were at least partially separated.
  • the granulate / extrudate produced can be dried and fractionated.
  • the granulates / extrudates produced can also be coated with one or more coatings of the further components 6 before, during, between or after drying and / or fractionation.
  • FIG. 4 shows the basic design for generating and using N / P compounds from nitrogen and sulfur-containing solution / suspension 12.
  • the nitrogen- and sulfur-containing solution / suspension 12 is supplied with precipitation reagents 10, 11 for the precipitation or crystallization of the N / P compounds.
  • a reagent 10 is at least one P compound for the formation of one or more N-phosphates.
  • Another reagent 11 serves as a reactant for the precipitation or crystallization of sulfate, for example an alkali or alkaline earth compound.
  • the addition of reagents 10 and 11 can take place simultaneously or staggered in time, also one after the other in stages with intermediate separation of the precipitation and crystallization products.
  • additional precipitation reagents 13 can be added to form specific precipitation or crystallization phases, such as, for example, Mg, K compounds.
  • the solution / suspension 12 can also be conditioned by additional precipitation reagents 13 or the pFI value can be adjusted.
  • the precipitation or crystallization reaction can take place in the same vessel as for supplying reagent 10 and / or 11 and / or in a separate vessel. An incubation period is awaited before the precipitation or crystallization reaction takes place.
  • N- (14) and sulfate compounds (15) precipitate and are separated from the solution / suspension.
  • N- (14) and sulfate compounds (15) are present separately, for example, when the N- (14) or the sulfate compounds (15) are initially precipitated or crystallized by adding a suitable precipitation reagent and separated from the solution / suspension the other component remains largely in solution and then the other compound is precipitated or crystallized out.
  • N and sulfate compounds are present together, for example, the precipitation or crystallization takes place simultaneously or the precipitated or crystallized compounds are not separated off separately. They can be present together in the form of a mixture of particles of different types and / or one type is coated or combined with one or more other types and / or crystallographic mixed phases are formed.
  • N- (14) and sulfate compounds (15) obtained in this way can be used directly as fertilizers or further processed or as a further component (nutrient component) in the method according to the invention for producing fertilizers from inorganic secondary phosphate, for example according to FIGS. 1 to 3.
  • FIG. 5 shows the basic structure of the electrochemical heavy metal depletion according to the invention (also to be referred to as an electrochemical reactor). There are two electrodes in a vessel that are connected to a voltage source.
  • the raw material suspension is introduced into the vessel with the electrodes or produced therein.
  • the raw material dispersion consists of at least one inorganic secondary phosphate and at least one reactant.
  • the reactant reacts at least in part with the inorganic secondary phosphate, proportions of the inorganic secondary phosphate, including the heavy metals contained therein, being dissolved and the remainder being present as undissolved (solid particles).
  • This raw material suspension of at least one liquid and one solid phase can also be referred to as an electrolyte solution.
  • one electrode becomes the cathode and the other becomes the anode.
  • heavy metal cations are at least partially reduced and, for example, deposited as metal or metal oxide at least partially on the cathode (adhesions on the cathode).
  • Embodiment 1 is a diagrammatic representation of Embodiment 1:
  • the device for electrochemical heavy metal depletion corresponds to FIG. 5.
  • the raw material suspension is accordingly transferred into a 250 ml glass vessel in which two carbon electrodes (5 ⁇ 8 cm) are located approximately 4 cm apart.
  • the raw material suspension is continuously stirred.
  • a current of 2.0 A is applied to the electrodes, one electrode becoming the anode and one electrode becoming the cathode.
  • the reaction time is 60 minutes.
  • the current is then switched off and the electrodes are removed from the suspension.
  • a deposit / film has accumulated on the cathode, which contains heavy metals, among other things, and which can be removed in dilute nitric acid (3%).
  • the cathode By separating the cathode with the heavy metal-containing coating / adhesion from the raw material suspension, at least some of the heavy metals present in the raw material suspension are separated from the raw material suspension.
  • the regeneration of the cathode with dilute nitric acid creates a waste solution containing heavy metals, which can be disposed of or recycled.
  • the cathode can then be reused.
  • the following table shows an example of the amount of heavy metals in the raw material suspension before and after the electrochemical separation and indicates the degree of separation in percent for some heavy metals.
  • the raw material suspension thus depleted of heavy metals can be converted into fertilizer granules in subsequent steps.
  • Embodiments 3 and 4 show two variants of this.
  • Embodiment 2 is a diagrammatic representation of Embodiment 1:
  • a larger amount of suspension with the same composition is produced as follows: 8 kg of water; 3.2 kg sulfuric acid (96%) and 4.0 kg sewage sludge ash (P205 content 18.3%, of which neutral ammonium citrate soluble 40% and ⁇ 1% water soluble; heavy metal content of 1.51 mg / kg for Cd, 14 mg / kg As, 613 mg / kg Cu)
  • the incubation time is again 25 minutes.
  • the electrochemical heavy metal separation then takes place in a manner analogous to that in embodiment 1.
  • the test setup was adapted to the larger amount of suspension by upscaling so that the test parameters for the electrochemical reaction were identical to those in embodiment 1.
  • the reaction time was again 60 minutes.
  • the heavy metal-depleted raw material suspension is pumped into a storage container and initially stirred there.
  • the following table shows an example of the removal rate for the amount of heavy metals from the raw material suspension achieved by the electrochemical depletion using selected heavy metals.
  • the heavy metal-depleted suspension is then processed further.
  • 3.4 kg of KCl are added with stirring and this mixture is further homogenized.
  • This raw material dispersion is then fed to a continuous fluidized bed system for spray granulation.
  • the spray granulation is controlled in such a way that an average granulate size of 3.5 mm results.
  • granules smaller than 2 mm and granules larger than 5 mm are separated by sieving and fed to the spray granulation process as core material, the granules larger than 5 mm being ground beforehand.
  • a core material in the form of a fluidized bed, onto which the raw material dispersion is sprayed, is required for spray granulation.
  • the core material of the species is preferably introduced; in the continuous process, the core material results from the recycling of the separated granulate fractions.
  • buffer tanks are installed in the process steps of heavy metal separation and granulation in order to ensure the chronological sequence of the continuous and discontinuous process steps running in parallel.
  • the heavy metal-depleted granulate produced has a round and compact granulate shape in the range 2-5 mm after the above-described equilibrium cycles have been set, a total P205 content of 7%, 92% of which is ammonium citrate-soluble and 38% is water-soluble, a total K20 content of 21 % and an S content of approx. 10%.
  • Embodiment 3 is a diagrammatic representation of Embodiment 3
  • a raw material suspension is produced. Unlike in exemplary embodiment 2, however, the electrochemical heavy metal separation then already takes place during the incubation period with a reaction time of 90 minutes. For this purpose, the raw material suspension produced is transferred to a separate electrochemical reactor according to the basic principle of FIG. Alternatively, the raw material can also be produced directly in this reactor.
  • the following table shows an example of the separation rate achieved for the amount of heavy metals from the raw material suspension for selected heavy metals.
  • a large part of the liquid phase is separated from the undissolved solid by means of a chamber filter press in such a way that an earth-moist solid mixture with a liquid phase content of 32% is formed.
  • the separated solution (liquid phase), which also contains nutrients, is returned to the process of raw material dispersion production for the next batch and replaces the above-mentioned water content in the formulation of the raw material dispersion in an equivalent amount.
  • continuously Continuous process management creates an equilibrium cycle of the dissolved substances in this sub-cycle. Accordingly, after this equilibrium has been established, the added amount of phosphate will pass through the sewage sludge ash to granulation and thus, as desired, into the granulate.
  • a major advantage over embodiment 2 is that part of the liquid phase is separated mechanically from the raw material dispersion. This means that significantly less water has to be evaporated, which saves considerable energy costs and makes the process much more economical.
  • the earth-moist solid mixture resulting from the solid-liquid separation is transferred to an intensive mixer (from Eirich R16W) and mixed intensively there. 3.4 kg of KCl are added as a fine powder and everything is mixed intensively.
  • the ratio of solid to liquid phase is set in the intensive mixer by adding water or a powder (e.g. sewage sludge ash) so that green granules of the desired size are formed during intensive mixing.
  • the green granules formed are then dried at 110 ° C. and fractionated into 2-5 mm. The fraction smaller than 2 mm and the fraction larger than 5 mm are returned to the subsequent granulation batches after previous grinding.
  • the heavy metal-depleted granulate produced has a round and compact granulate shape in the range of 2-5 mm after setting the above-described equilibrium cycles, a total P205 content of 7%, of which 90% is ammonium citrate-soluble and 28% is water-soluble and a total K20 content of 21 % and an S content of approx. 10%.

Abstract

L'exploitation agricole permet d'extraire des matières premières minérales du sol, telles que des composés contenant du phosphore par exemple, qui doivent être de nouveau compensées par un apport ultérieur d'engrais minéraux. L'exploitation matérielle et énergétique de la biomasse, par exemple à partir de déchets ménagers ou de boues d'épuration, implique l'extraction de nutriments et d'importantes quantités de matière organique provenant des cycles naturels des matières. La préservation de la fertilité du sol par l'utilisation d'engrais minéraux artificiels à partir de ressources fossiles doit être évaluée de manière critique du point de vue écologique ; d'une part, en raison de la destruction environnementale et, d'autre part, en raison de l'apport de métaux lourds dans les sols par le biais des engrais minéraux. Le phosphore est une matière première limitée et son utilisation efficace pour obtenir des sols fertiles dans un contexte de croissance démographique mondiale est très importante. Du point de vue de la durabilité, la fermeture des cycles de nutriments naturels revêt une importance croissante et propose en outre une source de matières premières locales jusqu'ici peu exploitées.
EP19835293.2A 2019-03-26 2019-12-20 Granulés d'engrais à base de phosphate secondaire appauvris en métaux lourds et procédé de production associé Pending EP3947321A1 (fr)

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DE102021205596A1 (de) * 2021-06-01 2022-12-01 Glatt Ingenieurtechnik Gesellschaft mit beschränkter Haftung Verfahren und Vorrichtung zur Herstellung von Düngemittelgranulat
EP4112590A1 (fr) * 2021-06-30 2023-01-04 Pontes pabuli GmbH Substrat de sols nutritif, procédé de fabrication et utilisation

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DE4414261A1 (de) * 1994-04-23 1995-10-26 Tomas Burmester Verfahren zur Dekontamination von Feststoffen mit Wiedergewinnung von Schwermetallen
DE102010034042B4 (de) 2010-05-05 2013-01-17 Axel Bruckert Verfahren zur Herstellung von Phosphat- und Mehrnährstoff-Düngemitteln
DE102013103770A1 (de) * 2013-04-15 2014-10-16 Rwe Power Ag Verfahren zur Gewinnung von phosphorhaltigen Verbindungen aus Klärschlamm
DK3041795T3 (da) * 2013-09-06 2020-03-23 Univ Denmark Tech Dtu Elektrodialytisk adskillelse af tungmetaller fra tungmetalholdigt partikelmateriale
DE102014006278B3 (de) * 2014-05-02 2015-02-26 Remondis Aqua Gmbh & Co. Kg Verfahren zur Reinigung von Roh-Phosphorsäure (z.B. MGA-Säure) durch Zugabe von Aschen aus Abfall-Verbrennungsanlagen umfassend die Gewinnung von reiner Phosphorsäure, Kalziumsulfat, wasserlöslichen Kalziumhydrogenphosphaten und Metallsalz-Lösung
EP3037396A1 (fr) 2014-12-22 2016-06-29 TSP GmbH Procédé de production d'un engrais contenant du phosphate à partir des cendres de boues d'épuration ou de déchets
DE102015101795A1 (de) * 2015-02-09 2016-08-11 Justus-Liebig-Universität Giessen Verfahren zur Gewinnung von phosphat-haltigen Verbindungen
DE102016116633A1 (de) 2016-09-06 2018-03-08 Glatt Ingenieurtechnik Gmbh Verfahren zur Herstellung von Düngemittelgranulat; Düngemittelgranulat
US11834382B2 (en) 2018-02-01 2023-12-05 Pontes Pabuli Gmbh Pedosphere-improving granulate, method for producing same, and use thereof

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