WO2019072814A1 - Procédé amélioré d'extraction, par dioxyde de carbone, de phosphates contenus dans des matières premières - Google Patents

Procédé amélioré d'extraction, par dioxyde de carbone, de phosphates contenus dans des matières premières Download PDF

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Publication number
WO2019072814A1
WO2019072814A1 PCT/EP2018/077420 EP2018077420W WO2019072814A1 WO 2019072814 A1 WO2019072814 A1 WO 2019072814A1 EP 2018077420 W EP2018077420 W EP 2018077420W WO 2019072814 A1 WO2019072814 A1 WO 2019072814A1
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Prior art keywords
reactor
carbon dioxide
suspension
extraction
liquid
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PCT/EP2018/077420
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German (de)
English (en)
Inventor
Eva OPITZ
Stefan Klein
Alexander Gottschall
Rainer Schnee
Martin MÜßIG
Ulrich Kotzbauer
Michael POGANSKI
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Chemische Fabrik Budenheim Kg
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Priority to EP18783477.5A priority Critical patent/EP3694621A1/fr
Publication of WO2019072814A1 publication Critical patent/WO2019072814A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D11/00—Solvent extraction
    • B01D11/02—Solvent extraction of solids
    • B01D11/0203—Solvent extraction of solids with a supercritical fluid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D11/00—Solvent extraction
    • B01D11/02—Solvent extraction of solids
    • B01D11/0215—Solid material in other stationary receptacles
    • B01D11/0223—Moving bed of solid material
    • B01D11/0226—Moving bed of solid material with the general transport direction of the solids parallel to the rotation axis of the conveyor, e.g. worm
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D11/00—Solvent extraction
    • B01D11/02—Solvent extraction of solids
    • B01D11/0261—Solvent extraction of solids comprising vibrating mechanisms, e.g. mechanical, acoustical
    • B01D11/0265—Applying ultrasound
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D11/00—Solvent extraction
    • B01D11/02—Solvent extraction of solids
    • B01D11/028—Flow sheets
    • B01D11/0284—Multistage extraction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D11/00—Solvent extraction
    • B01D11/02—Solvent extraction of solids
    • B01D11/0292—Treatment of the solvent
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05B—PHOSPHATIC FERTILISERS
    • C05B15/00—Organic phosphatic fertilisers
    • 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
    • C05F—ORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C, e.g. FERTILISERS FROM WASTE OR REFUSE
    • C05F1/00—Fertilisers made from animal corpses, or parts thereof
    • C05F1/005—Fertilisers made from animal corpses, or parts thereof from meat-wastes or from other wastes of animal origin, e.g. skins, hair, hoofs, feathers, blood
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05F—ORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C, e.g. FERTILISERS FROM WASTE OR REFUSE
    • C05F3/00—Fertilisers from human or animal excrements, e.g. manure
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05F—ORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C, e.g. FERTILISERS FROM WASTE OR REFUSE
    • C05F7/00—Fertilisers from waste water, sewage sludge, sea slime, ooze or similar masses
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05F—ORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C, e.g. FERTILISERS FROM WASTE OR REFUSE
    • C05F9/00—Fertilisers from household or town refuse
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05F—ORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C, e.g. FERTILISERS FROM WASTE OR REFUSE
    • C05F9/00—Fertilisers from household or town refuse
    • C05F9/04—Biological compost
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/26—Treatment of water, waste water, or sewage by extraction
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/38—Treatment of water, waste water, or sewage by centrifugal separation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/38—Treatment of water, waste water, or sewage by centrifugal separation
    • C02F1/385—Treatment of water, waste water, or sewage by centrifugal separation by centrifuging suspensions
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/5263—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using natural chemical compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/105—Phosphorus compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/06—Controlling or monitoring parameters in water treatment pH
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2301/00—General aspects of water treatment
    • C02F2301/04—Flow arrangements
    • C02F2301/046—Recirculation with an external loop
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2301/00—General aspects of water treatment
    • C02F2301/06—Pressure conditions
    • C02F2301/066—Overpressure, high pressure
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A40/00—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production
    • Y02A40/10—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production in agriculture
    • Y02A40/20—Fertilizers of biological origin, e.g. guano or fertilizers made from animal corpses
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/141—Feedstock
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/141—Feedstock
    • Y02P20/145—Feedstock the feedstock being materials of biological origin

Definitions

  • the present invention relates to an improved process for obtaining phosphates by extraction of a suspension of a phosphate-containing raw material with carbon dioxide and to a process plant with which this process can be carried out.
  • Raw phosphate is a non-renewable, fossil resource. Estimates of how long these resources can meet our needs are very different. The deposits are limited to a few countries or regions. Most countries are almost completely dependent on imports, which leads to risks in terms of security of supply and susceptibility to price fluctuations. Alternative sources of phosphate have to be found, and the recovery of phosphates from sewage sludge has proven promising in the recent past.
  • DE 10 2009 020 745 itself relates to a process for the recovery of valuable substances, in particular phosphate, from sewage sludge products by extraction of an aqueous, alcoholic or aqueous-alcoholic suspension of the sewage sludge product with gaseous or supercritical carbon dioxide. This process can be roughly divided into three process steps: extraction with carbon dioxide, solid / liquid separation and phosphate precipitation.
  • sewage sludge is contacted with gaseous carbon dioxide at elevated pressure.
  • the pH is ideally between about pH 4 and pH 6, since the phosphates bound to the sewage sludge matrix can best dissolve in this area.
  • the sludge particles are separated from the liquid phase, and the carbon dioxide exits the sludge water freed of sewage sludge particles under normal pressure is recovered and returned to the process.
  • the sludge water freed from the sewage sludge particles and the carbon dioxide is finally fed to the third process step, the phosphate precipitation. In this case, the dissolved phosphates are precipitated, so that they can then be supplied for further use.
  • the object of the present invention was to provide an improved process for the carbon dioxide extraction of phosphates from raw materials, in which the expected or even higher yields are achieved.
  • This object is achieved by a process for obtaining phosphate from a raw material by extraction with carbon dioxide, in which one
  • step (D) from the liquid obtained in step c) precipitated therein phosphates and separated from the liquid, characterized in that the steps (a) and (b) are carried out in a continuously operated reactor until the pH of the suspension ⁇ 6.9.
  • raw materials from which phosphates can be obtained in the sense of the present invention, refers here to those which extractable phosphorus or extractable phosphorus. phate included.
  • this includes sewage sludge, sewage sludge ash, sewage sludge, sewage sludge, digestate, residues from the fermentation of biomass, compost, farmyard manure, liquid manure, animal fat, animal meal, meat bone meal, biowaste, garden waste, Bonderschlämme, phosphate-containing technical waste solutions, phosphate-containing wastewater, by-products of food production including casein, cheese dust, meat and fish wastes and presscakes remaining in the production of edible oil.
  • phosphate or "phosphates” is understood to mean all salts and esters of orthophosphoric acid (H3PO4) and salts and esters of orthophosphoric acid condensates (for example pyrophosphates, triphosphates, polyphosphates and metaphosphates).
  • H3PO4 orthophosphoric acid
  • salts and esters of orthophosphoric acid condensates for example pyrophosphates, triphosphates, polyphosphates and metaphosphates.
  • the term "continuously operated” is to be understood as follows: In continuous operation, the reactor is continuously filled with new starting materials at one point, and elsewhere the reaction mass is continuously withdrawn with the products formed from the reactants In contrast, in batch operation, a reactor is charged once with the reactants, and after completion of the reaction, the reaction mass is removed once with the resulting products and the remaining reactants.
  • the inventively proposed implementation of the method for obtaining phosphate from a raw material by extraction with carbon dioxide in a continuously operated reactor offers the advantage that, unlike the method described in DE 10 2009 020 745 A1 in a batch stirred tank much better mixing and Thus, a more homogeneous adjustment of the pH required for the carbon dioxide extraction is achieved. This ultimately leads to the fact that a significantly higher yield can be achieved with the continuously operated reactor of the invention than with the discontinuously operated stirred tank known from the prior art (in particular DE 10 2009 020 745 A1).
  • a significant advantage that arises in the execution of the extraction process according to the present invention is a more homogeneous lowering of the pH, which is still at about pH 7 in the untreated starting suspension. Particularly advantageous is the better mobilization of phosphate, which can be observed from a pH of ⁇ 6.9. If the pH is in the suspension at s 6.9, relatively good phosphate yields are already achieved. Even more preferred is a pH in the suspension of ⁇ 6.5. Particularly preferred is a pH in the range of 5.0 to 6.0.
  • the aforementioned advantage is achieved, in particular, by carrying out steps (a) and (b) of the process according to the invention in a continuously operated reactor. The use of a tube reactor has proven particularly suitable in this respect.
  • tube reactor in the context of the present invention refers to a tubular reactor operating according to the "plug-flow" principle, in which the reaction mass flows from one end (proximal end) of the tube to raw material suspension in the reactor which has not yet been treated with carbon dioxide At the other end (distal end) of the tube, at which carbon dioxide-treated raw material suspension is removed from the reactor, is transported, where the material conversions take place along the transport path through the reactor tube Reactor space whose length is much larger than its diameter.
  • the "diameter" of a tubular reactor means the average internal diameter of the reaction space of the tubular reactor.
  • reaction space designates the region in which the reaction conditions required for carrying out the reaction are present.
  • the diameter of the tubular reactor is in the range of 5 to 100 cm, preferably in the range of 8 to 50 cm, and more preferably in the range of 10 to 25 cm.
  • the ratio of the length of the reactor interior to the diameter of the interior of the reactor is at least 50: 1, at least 100: 1, at least 200: 1, at least 300: 1, at least 400: 1 or even at least 500: 1.
  • Some embodiments have a length to diameter ratio of up to 1,000: 1, but some particular embodiments may also have a ratio of up to 2,000: 1, up to 5,000: 1 or even up to 10,000: 1.
  • an eccentric screw pump is provided at the proximal end of the reactor.
  • the tube of the tubular reactor therefore has at least 5, at least 10, at least 20 or even at least 30 turns, in which the course of the tube in the transport direction an angle in the range of 90 ° to 180 ° describes.
  • Embodiments with as many turns as possible by 180 °, for example at least 5, at least 10, at least 20 or even at least 30 turns by 180 °, can be particularly advantageous.
  • either gaseous or liquid carbon dioxide is introduced.
  • the inventors of the present application have found that in certain embodiments of the invention, a higher yield can be achieved when non-gaseous carbon dioxide is introduced into the reaction mass for extraction, as described in DE 10 2009 020 745 A1, but liquid carbon dioxide.
  • Decisive for this feature is the state of aggregation of the carbon dioxide in the feed line through which the carbon dioxide is passed, i. until the time the carbon dioxide enters the reactor through the opening of the feed line.
  • the physical state of the carbon dioxide introduced can change after it has entered the reactor space.
  • an even higher yield can be achieved if both gaseous and liquid carbon dioxide are introduced into the reaction mass for extraction.
  • the molar ratio of the carbon dioxide in these two states of aggregation can be varied according to the invention.
  • the molar ratio of supplied gaseous to supplied liquid carbon dioxide is in the range of 90:10 to 10:90.
  • the percent mole fraction of liquid carbon dioxide based on the total amount of carbon dioxide supplied is at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, or even at least 80%.
  • a more homogeneous distribution of the carbon dioxide responsible for the extraction of the phosphate from the raw material into the reaction mass in certain embodiments can also be achieved by subjecting the reaction mass to ultrasound (frequency> 16 kHz).
  • the ultrasonic frequency is in the range of 20 kHz to 1 GHz. In certain embodiments, it may be preferred that the ultrasonic frequency is at most 300 kHz or only 250 kHz.
  • Included in the present invention are both those embodiments in which the introduction of the liquid carbon dioxide and the gaseous carbon dioxide takes place via one and the same supply line, as well as those embodiments in which the introduction of the gaseous carbon dioxide and the introduction of the liquid carbon dioxide via separate Supply lines takes place.
  • the introduction of the gaseous carbon dioxide takes place via at least one first supply line and the introduction of the liquid carbon dioxide via at least one second supply line.
  • the first lead is in the process direction, i. in the direction in which the reaction mass moves through the reactor before the second supply line.
  • the second feed line is in the process direction before the first feed line.
  • the at least one first lead and the at least second lead may also be at the same level with respect to the process direction.
  • first and a plurality of second leads which are arranged either in groups or alternately.
  • the first and / or second leads are all disposed on the top or bottom of a longitudinally horizontally oriented reactor.
  • the first and / or second feed lines are distributed over the circumference of the cross-cut reactor.
  • the feed line or lines are arranged only at the beginning, ie within the first 10% of the reactor interior space, in the longitudinal direction of the tube reactor. In certain embodiments, only in the first quarter, only in the first third, only in the first half or in the first two-thirds of the reactor interior length first and / or second leads for carbon dioxide. In certain embodiments, each first and / or second supply line has its own quantity regulator with inlet valve controlled thereby. In other embodiments, the amount of carbon dioxide supplied is controlled via the first and / or second feed lines via a common flow regulator. In some embodiments, a plurality of first and / or second supply lines are assigned in groups to a common volume controller.
  • the extraction of the phosphates from the raw material takes place under an elevated pressure (stage b)).
  • the elevated pressure in the reactor is in the range of 2 to 100 bar, preferably in the range of 3 to 50 bar, more preferably in the range of 5 to 25 bar, and most preferably in the range of 8 to 16 bar.
  • the extraction step is carried out at a pressure in the reactor of at least 6 bar or even at least 8 bar.
  • the maximum pressure in the reactor is in certain embodiments 25 bar, 20 bar or even 16 bar.
  • the specific selection of a specific pressure depends in particular on the raw material to be extracted, the selected suspending agent, the process temperature and the molar ratio of gaseous to liquid carbon dioxide.
  • the extraction of the phosphates from the raw material takes place at a temperature in the range of 5 to 100 ° C.
  • the extraction step is carried out at a temperature in the reactor of at least 10 ° C or even at least 15 ° C.
  • the maximum temperature in the reactor is 75 ° C, 50 ° C or 40 ° C in certain embodiments.
  • a particularly preferred temperature range is from 20 to 35 ° C.
  • the specific selection of a specific temperature depends in particular on the raw material to be extracted, the selected suspending agent, the process temperature and the molar ratio of gaseous to liquid carbon dioxide.
  • the pressure increased in step b) is lowered between steps b) and c).
  • the pressure reduction has the advantage that under reduced or normalized pressure for the subsequently required separation of undissolved solids from the suspension, it is also possible to use those methods which can be carried out better under non-elevated pressure conditions.
  • the pressure reduction is carried out to a pressure in the range of less than 1 bar. The concrete selection of the pressure takes place depending on which method for separating solids from the suspension is followed.
  • the pressure reduction can take place either at the end of the process route in the last section of the reactor or in a separate flash tank, which adjoins the reactor.
  • the pressure reduction can be done in one step or two or more stages in one arranged after the reactor expansion tank or in two or more successively arranged expansion tanks.
  • Facilities for foam destruction are provided in a flash tank since, under reduced pressure, in particular, the carbon dioxide introduced into the reaction mass in gaseous state outgass, which results in a considerable amount of foaming.
  • foam destruction means include, but are not limited to, nozzles for spraying liquid (e.g., water), mixers (stirrers), surfactant feeders, special internals (e.g., foaming screens), and ultrasonic sources.
  • step c) of the process according to the invention the separation of undissolved solids from the suspension takes place.
  • the separation of the undissolved solids is performed by at least one sieve and / or at least one filter (e.g., filter press, vacuum band filter).
  • the separation of the undissolved solids from the suspension is carried out by centrifugation.
  • various methods of separating undissolved solids from the suspension are combined to ensure that no subsequent sludge particles contain any sludge particles in the solution to be precipitated.
  • sewage sludge particles would lead to high carbon contents in the precipitated product, which is undesirable in particular for the products which are to be used as plant-available calcium phosphate fertilizers.
  • at least one centrifugation and at least one filtration are preferably carried out.
  • a first filtration step is carried out, followed by centrifugation and finally a second filtration step.
  • the second filtration step is a microfiltration (pore size> 100 nm to 100 ⁇ ), ultrafiltration (pore size 2 - 100 nm) or nanofiltration (pore size ⁇ 2 nm).
  • the phosphate dissolved in the filtered liquid is precipitated in stage b) of the process according to the invention.
  • This step is carried out in a precipitation reactor in principle according to any method known to the expert for the precipitation of phosphates. Examples include alkalization, sonication, microwave irradiation, and addition of precipitating reagents, e.g. Calcium hydroxide suspension (milk of lime) or magnesium salts.
  • the separation of the phosphates precipitated in process stage d) from the liquid can in principle also be carried out by any method known to the person skilled in the art. At a certain embodiment of the invention, screens and / or filters, such as a filter press are used for this purpose.
  • the phosphates precipitated in stage d) are separated from the liquid via a centrifuge.
  • the precipitated in step d) phosphates are separated via a settling funnel or a hydrocyclone from the liquid, wherein a hydrocyclone is associated with the particular advantage that very fine-grained dicalcium phosphate, which sediments only very slowly in this way very effectively can be separated.
  • the use of a hydrocyclone for separation also requires no flocculants, as is the case with some other other process.
  • flocculants which can be used in the precipitation and separation of the phosphates are known to the person skilled in the art. Flocculants based on starch are particularly preferred according to the invention.
  • various pretreatment methods can additionally be used, in particular to disintegrate the sewage sludge, disintegration of the sewage sludge meaning that the cells contained are digested by microorganisms. As a result, the intracellular components, and thus in particular the phosphates contained therein, are made available for CO 2 treatment and recovery.
  • the disintegration of the cell structures can take place both before and after the sludge digestion.
  • a disintegration in front of the digester in addition to the increased phosphorus yield and the increase in gas yield in digester, resulting in the view of the wastewater treatment plant operator is very beneficial.
  • the sewage sludge disintegration can be realized by various chemical and / or physical methods, such as: - grinding the sewage sludge, e.g. in a wet mill (bead mill),
  • the present invention also encompasses the provision of a process plant for obtaining phosphate from an aqueous, alcoholic or aqueous / alcoholic suspension of a raw material by extraction with carbon dioxide, which is suitable for carrying out the process according to the invention.
  • the system has the following facilities:
  • the process plant is characterized in particular by the fact that the extraction reactor is a reactor which is suitable for continuous operation, wherein at least one sensor is arranged on the reactor with which the pH of the suspension in the reactor is determined during operation can be.
  • a continuously operated reactor of the type claimed here is associated with the advantages which have already been described in detail above.
  • at least one sensor is arranged on the reactor, with which during operation the pH of the can be determined in the reactor suspension.
  • the at least one sensor is located at the distal end of the reactor or at a distal end of a reactor section.
  • the sensor serves to control whether the suspension at the distal end of the reactor or at a distal end of a reactor section, which required the inventive method pH (at least - ⁇ 6.9) has reached. If this is the case, no change must be made to the process management. If the target pH has not yet been reached, either the procedure must be changed or the reaction time must be extended. If the reaction time needs to be extended, either the flow rate through the reactor may be slowed down or the length of the distance the carbon dioxide-added suspension has to travel needs to be extended, and for the latter two different specific embodiments of the invention are proposed.
  • the first specific embodiment provides that the suspension, whose pH has not yet reached the desired threshold, is at least partially returned to the proximal section of the reactor in order to at least partially pass through the reactor again.
  • a recirculation loop is provided on the reactor, through which at least part of the suspension is returned from the distal end of the reactor into the section at the proximal end of the reactor.
  • the recirculation loop has a cross section corresponding to at least half, more preferably at least two thirds, more preferably at least 90% of the cross section of the reactor.
  • a return pump is arranged on the recirculation loop, with which the returned suspension is pumped through the recirculation loop.
  • the reaction mass is recycled back to the region of the tubular reactor immediately after the carbon dioxide feed inlets. In other embodiments, the reaction mass is recycled to the region of the reactor immediately before the inlet for the introduction of carbon dioxide.
  • the decision as to which of the two recycle options mentioned will depend in particular on how far away the pH of the reaction mass deviates from the target and to what extent this requires the introduction of additional carbon dioxide.
  • the reactor has at least two sections merging in the longitudinal direction, wherein the suspension whose pH has not yet reached the desired threshold at the end of the first section is passed into the adjoining second section of the reactor also to go through this second section of the reactor.
  • the suspension can be forwarded to the downstream system components in which these method steps are executed for further processing according to steps c) and d).
  • an outlet is provided at the end of the first reactor section, can be passed through the reaction mass in a bypass circuit
  • a third reactor section is arranged at the proximal end of the second reactor section, and optionally then a fourth, fifth or nth reactor section. If the desired threshold value is reached at the end of one of these additional sections, the suspension can also be forwarded here via a bypass circuit for further processing according to steps c) and d) to the downstream system components in which these method steps are executed.
  • suspension changes to the next section.
  • further feed lines for carbon dioxide are provided in certain embodiments at the proximal end of the second, third, fourth, fifth or n-th reactor section.
  • the principle of the recycle loop is combined with the principle of merging reactor sections, each having outlets at their ends, via the reaction mass into a bypass loop.
  • mixing devices on.
  • mixing devices suitable for this purpose are known to the person skilled in the art.
  • the intended mixing devices are paddles and / or one or more conveyor screws and / or static or dynamic mixers.
  • the plant has means for at least partially exposing the reactor to ultrasound.
  • the application of ultrasound preferably takes place in particular in the region in which the carbon dioxide is introduced into the reactor.
  • the system according to the invention may also have one or more of the following components: a device for disintegrating the sewage sludge,
  • a filtration unit for separating sewage sludge particles from the centrate obtained by centrifugation.
  • the reactor of the process plant claimed herein must be suitable at least for operation under pressure in the abovementioned ranges.
  • either means for introducing gaseous carbon dioxide or for introducing liquid carbon dioxide are arranged on the reactor.
  • certain embodiments of the plant according to the invention have a device which is suitable both for the introduction of gaseous carbon dioxide and for the introduction of liquid carbon dioxide in the extraction reactor is suitable
  • the extraction reactor is characterized by having separate feed lines for introducing the gaseous carbon dioxide on one side and introducing the liquid carbon dioxide on the other side.
  • at least one first supply line for introducing the gaseous carbon dioxide and at least one second supply line for introducing the liquid carbon dioxide are provided.
  • a flash tank separate from the reactor space is provided by lowering the pressure prevailing in the interior of the reactor.
  • means for foam destruction are provided in this expansion tank, as already described in detail above.
  • FIG. 1 shows an R & I flow chart of the reactor region of a process plant which is suitable for obtaining phosphate from a raw material suspension by the process according to the invention.
  • a tubular reactor 9 at the distal end 1, the introduction of the raw material suspension to be extracted takes place.
  • This raw material suspension is transported via a screw pump 2 through the pipe 3 and there mixed with carbon dioxide.
  • injectors 6, 7 are provided, via which either gaseous carbon dioxide 4 or liquid carbon dioxide 5 can be fed into the pipeline 3.
  • the first injector for carbon dioxide here injector 6 for gaseous carbon dioxide 4
  • the actual tube reactor 9 begins, in its further course in the embodiment shown here, a static Mixer 8 is arranged.
  • the tube reactor shown here is a so-called loop reactor, which has several turns by 90 ° 10, 1 1 and in particular a whole series of turns by 180 ° 12, 13, 14, 15. Overall, 16 turns by 180 ° are realized in the embodiment shown here, to which it depends for the purpose of mixing the reaction mass in particular.
  • the loops of the reactor shown here are divided longitudinally into three sections which merge into one another, each of which makes up about one third of the total length of the loops of the reactor.
  • a pH measuring probe 16, 18, 20 is arranged in the embodiment shown here, via which the pH value in the reaction mass, which has passed the preceding section of the loop reactor, can be determined.
  • the shut-off devices 29 or 30 can be opened so that the closed reaction devices 17 and 19 contain the reaction mass via the bypass circuit 28, ie bypassing the other sections of the block Tube reactor, are derived in the form of sufficiently treated with carbon dioxide suspension from the reactor part 31 of the plant.
  • the shut-off device 32 is then closed while at the same time the shut-off device 21 is opened so that the pump 23 can pump the reaction mass back to the proximal end of the reactor.
  • the first return option 24 leads the reaction mass with open shut-off device 25 back into the region of the tubular reactor immediately after the two injectors 6 and 7 for the introduction of carbon dioxide
  • the second return option 26 returns the reaction mass with the shut-off device 25 closed and the shut-off device 27 open to the region of the reactor which lies immediately before the injectors 6 and 7 for the carbon dioxide.
  • the decision as to which of the two named return options is selected depends in particular on how far away the pH measured by the pH probe 20 deviates from the target and to what extent this requires the introduction of additional carbon dioxide.
  • the reaction mass sufficiently treated with carbon dioxide can be supplied via the discharge line 31 to the further treatment steps when the shut-off device 21 is closed and the shut-off device 32 is open.
  • the pressure is first lowered in a flash tank and then the separated still undissolved solids are removed, the corresponding devices not being shown in the flow chart shown in FIG. EXAMPLES
  • the reactor region is constructed according to the flow chart, which is shown in Figure 1, comparative experiments were carried out in which the extraction with carbon dioxide under different conditions.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Physics & Mathematics (AREA)
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  • Life Sciences & Earth Sciences (AREA)
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Abstract

L'invention vise à fournir un procédé d'extraction, par dioxyde de carbone, de phosphates contenus dans des matières premières, ledit procédé devant permettre d'atteindre de hauts rendements. A cet effet, l'invention concerne un procédé selon lequel (a) du dioxyde de carbone est introduit dans une suspension alcoolique ou aqueuse/alcoolique de la matière première, (b) on laisse agir le dioxyde de carbone se trouvant dans la suspension sur la matière première, sous pression élevée, (c) les solides non dissous sont séparés de la suspension, avec pour effet d'obtenir un liquide, puis (d) précipiter hors du liquide obtenu à l'étape c) les phosphates dissous dedans et de les séparer du liquide, ledit procédé se caractérisant en particulier en ce que les étapes a) et b) sont exécutées dans un réacteur actionné en continu, jusqu'à ce que le pH de la suspension soit ≤6,9. L'invention concerne en outre une installation technique permettant de mettre en oeuvre ledit procédé.
PCT/EP2018/077420 2017-10-12 2018-10-09 Procédé amélioré d'extraction, par dioxyde de carbone, de phosphates contenus dans des matières premières WO2019072814A1 (fr)

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EP18783477.5A EP3694621A1 (fr) 2017-10-12 2018-10-09 Procédé amélioré d'extraction, par dioxyde de carbone, de phosphates contenus dans des matières premières

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DE102017123807.7A DE102017123807A1 (de) 2017-10-12 2017-10-12 Verbessertes Verfahren zur Kohlenstoffdioxid-Extraktion von Phosphaten aus Rohstoffen
DE102017123807.7 2017-10-12

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CN115475408A (zh) * 2022-08-31 2022-12-16 中材锂膜(宁乡)有限公司 一种湿法隔膜萃取装置及工艺
CN117185596A (zh) * 2023-08-01 2023-12-08 河北工业大学 一种超临界二氧化碳萃取污泥中氮磷元素的方法

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CN112876036A (zh) * 2021-02-23 2021-06-01 扬州阿鲁达环境科技有限公司 一种基于超声波的含油污泥处理系统及其工艺
CN115475408A (zh) * 2022-08-31 2022-12-16 中材锂膜(宁乡)有限公司 一种湿法隔膜萃取装置及工艺
CN115475408B (zh) * 2022-08-31 2024-01-19 中材锂膜(宁乡)有限公司 一种湿法隔膜萃取装置及工艺
CN117185596A (zh) * 2023-08-01 2023-12-08 河北工业大学 一种超临界二氧化碳萃取污泥中氮磷元素的方法
CN117185596B (zh) * 2023-08-01 2024-06-14 河北工业大学 一种超临界二氧化碳萃取污泥中氮磷元素的方法

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