DE19513560A1 - Absorbent granules made of diatomaceous earth - Google Patents

Abstract

Absorbent granules for horticultural use, are composed of diatomaceous earth mixed with a urea formaldehyde resin in an amount of 20-50 pts. resin to 100 pts. earth. Absorbent granules are produced by mixing damp diatomaceous earth with resin which contains an acid catalyst. Granules are shaped by extruding and then dried at 95-180 deg. C. The earth is initially taken from filter cakes obtained in a beer- or wine-making plant.

Description

The present invention relates to novel absorbent granules and their use, in particular as carrier materials for Pflan Zen.

The carrier materials used for hydroponics (hydroponic culture) or used for pot plant cultures are sand, vulkani pumice stone, perlite, vermiculite, expanded clay, tree trunk bark, brew ner or bright peat.

The expanded clay or the tree trunk bark have the disadvantage that they in the range between 15 and 150 microns are not very porous. The what The retention of these carriers is therefore very limited, as a result of which Carriers must be permanently irrigated in a hydroponic culture.

The perlites or vermiculites show in the range between 15 and 150 μm more porosity than expanded clay or tree trunk bark. The Ventilation of these substrates is important because the zwi The water contained in the granules can drain off easily. These Carrier materials are very often used in hydroponics.

Sand can essentially do more in intergranular porosity save as the aforementioned four support materials, wherein due to the water in the pores only little volume for the air remains. Therefore, the sand used as a culture medium requires a frequent watering at regular intervals. Such a perma However, irrigation leads to the suffocation and rottenness of the worms individually.

Peat as carrier material is more for potted plants than for hydroponics suitable. He owns air and water retention capacities that allow him to a popular material for horticulture. He may, however do not dry out because otherwise it is hydrophobic and therefore very difficult to moisturize (see Soil Science, 1991, 152-2, pp. 100-107, B. Valat,  C. Jouany and L.M. Riviere: Characterization of the Wetting of Air Dried Peats and Composts). Another disadvantage is that he is in the Over time, it deepens the aeration of the roots and thus limiting the growth of the plants.

A good substrate for plants, on which the present Invention is characterized by:

• - a water requirement of at least 8%,
• - An air volume in the bulk volume of the carrier material of more than 20%,
• - a structural stability of more than 80%,
• a pH between 3.5 and 8,
• - a very high permeability, which is more than 15 Darcy.

Other desired properties are:

• - a low content of heavy metals,
• a good mechanical resistance to compaction,
• - a good cation exchange capacity (Ca⁺⁺, Na⁺, Mg⁺, K⁺), which at Pot plant cultures greater than 100 milliequivalents / dm³ or at Hydroponic cultures is less than 100 milliequivalents / dm³.
• - a slight rewet after a random drying voltage.

Good mechanical resistance during sterilization with Water vapor is also a beneficial property for hydroponics because they are said to be bacteriologically inert, especially when It's about a carrier material at the end of the cultural cycle like to use the.

Special features are specified below:

The water retention of a carrier material is considered the mass of the absorbed water per kg of hydroponic carrier material out suppressed. The water that can be assimilated by the plants or that for the Plant usable storage water is the water that is in the pores  a size of 1.5 to 150 microns is stored. This is from the Water needs, so the water that is easily extracted by the plant can be distinguished, taking the water in the pores with a size of 15 to 150 microns is stored. That in the pores with The smaller size of 1.5 to 15 μm stored water is through the plant can be assimilated, which, however, due to the required Soaking up the water creates stress conditions: hence this becomes Water here referred to as stress water. That in the pores with one Size below 1.5 μm stored water is not from the plant assimilable and thus useless for the plant: therefore it is here as not usable storage water called. More natural, in Steinbrü chen occurring tone contains, for example, be 2 to 3 times weight of water, but the plants can not thrive in it hen because the pore size of this clay is less than 1.5 microns.

The usable storage water and water needs are considered as per zentual ratio of the water occupied volume and the occupied by the dry plant substrate volume (Bulk volume of the plant substrate). These two fac They are prepared according to the method of D. Tessier and J. Berrier "Utilization de la microscopie à balayage dans l'observation de sols soumis à diff'rents pH ", Science du Sol, 1, 67-82, 1979, is described.

Structural stability is an important criterion in relation to Crumbling of a carrier material under the influence of extensive ger and frequent irrigation and its stability to water; for certain clay or clay-containing earths disintegrate on their own due to an increase in capillary water in the pores or channels of the materials. The material disintegrates due to the explosion of the enclosed senen air bubbles and weathered thus. Man tests the material by in a 50 ml test tube 5 g of dry carrier material and then 25 ml of water is added. The test tube is closed and 30 Continuously rotated for minutes. The structural stability  refers to the percentage by mass of particles that have a Have dimension of about 1 mm.

The measurement of the pH is carried out by taking a part of the granules with 5 times its weight of water and then measuring the pH for 15 minutes. The plants can assume a basic carrier material poorly.

The permissible heavy metal content in a carrier material for plants is determined by the standard AFNOR NFU 44-041.

The cationic exchange capacity of a carrier material for plants generally depends on the use of the substrate, either as a hydroponic or potted plant culture. An ion out Exchange capacity of 0 is not a disadvantage for hydroponics while they are important for a potted plant culture. A value above 100 milliequivalents (mVal) of ions per dm³ is for potted plant cultivation sufficient. If the value is below 100 mVal / dm³, the Trä germaterial of the culture are regularly mixed with some fertilizer.

The permeability of the support material must allow for flow and rapid droplet formation of the water throughout the substrate. It is generally measured in units of Darcy, ie 0.987 x 10 ^-12 m 2 in MKSa units, according to the method proposed in FR-PS 23 67 282.

The kieselguhr has so far no practical use as Trä found germaterial for plants. Still, she is a powder that absorb about twice their weight in water can. Examination of their water absorption capacity shows that it is saturated with 1.8 kg of water per kg, but their water requirement is about 4%. The water is generally in the pores with a Size of less than 1.5 microns absorbed and sown by water porosity is no longer accessible to the air. The free Volu  The amount of these pores is less than after moistening the substrate 0.5%: The moistened diatomaceous earth is a sludge suitable for the Application is less suitable because the plants without air supply die off at root level.

Thus, DE-PS 31 20 782 describes the preparation of a carrier for plants by granulation of already used diatomaceous earth, which comes from filter cake from breweries. These cakes will be agglomerated with clay. However, this process leads to dry Products with a water requirement between 4 and 7% of the bulk volume (to be compared with 20 to 40% for different peat depositors th). The structural stability of the dried and calcined Pro depending on the origin of the filter cake between 50 and 80% is not enough to make it a good carrier material for hydro cultures. Regardless of which tone is used, the granules of the filter cake have a pH between 8 and 10, when they are calcined.

In general, it can be assumed that the binders are the pores clog the materials to which they are connected. This would be not a disadvantage for fuel or building materials, but it prohibits in the Case of producing strand materials for plants containing a require high water demand. That's why the experiments are for the agglomeration of absorbent earth according to the prior art Technique is the result of the incorporation of adsorbing earths in Resin foam (see, for example, JP-A-55 125 132 or JP-A-80 125 132 or Mitsui Toatsu Chem. Inc., DD-A-2 17 795 of VEB Agroch. Piesteri), the by crushing the polymerized mass to the desired Granulometry be attributed.

It has now been found that it is possible to absorb such the granules, in particular as support materials for plants, herzu make strands of a mixture of diatomaceous earth and Carbamide / formaldehyde resins produced, which are after the Polymeri  dry and then optionally followed by the crushed desired size. The absorption efficiency of through This product was extremely simple process unpredictable. Contain the preferred compositions based on the dry weight, 100 parts diatomaceous earth with 20 to 50 Parts of a carbamide / formaldehyde resin, which is a melamine / form aldehyde resin can be.

The inventive method consists in a diatomaceous earth whose Water content was adjusted to about 40% with a carba mid / formaldehyde resin containing an acid catalyst, for example wise NH₄Cl, mixes. The mixture is carefully kneaded and then extruded, for example with a Kahl extruder. The crowd will then pressed through a nozzle, which is also over with friction rollers can accomplish a grid. You can also do it by means of a Extrude Pinette extruders by extruding the stock Carboxymethyl cellulose type additive is added. The strands are then dried between 95 and 180 ° C to the Resin crosslink, and optionally crushed to the requirement ments of the user to the dimensions, which are generally between 1 and 4 mm to correspond.

The resins are of the type used as binders in the manufacture of fuel or for the production of chipboard used. The resin is made by condensation of formaldehyde and Urea produced. It is either in aqueous form with 50 to 80% dry content of the resin or sold in dried form.

The kieselguhr used in the present invention must be one Calcination treatment be subjected to their permeability between 0.03 and 15 Darcy. That's the same treat which is subject to diatomaceous earth when converted into filter aids is working. This permeability state of diatomaceous earth is necessary but enough to create enough open pores in the material  alone is not enough. Processing the diatomaceous earth into powder ensures an intergranular permeability indispensable for root respiration. The magnitude of this permeability is not the same comparable material. The permeability increases with the square of the diameter of the open pores, of a few millimeters stacked granules up to several tens of microns at the Diatomaceous earth.

The kieselguhr is however for the production of conventional Trä germaterial for plants is too expensive a raw material. Your permeability qua Quality does not become due to prior use as a filtration aid diminished, but also remains in the used Filterku chenmaterial, z. From breweries or viticulture, making this kieselguhr an economical source material for the preparation of the absorbent granules according to the invention becomes. The use of these filter cakes is for the present Invention advantageous because they represent raw materials without value and on the other hand their disposal is becoming increasingly expensive. Necessary it is only to let them partially dry to the moisture from 65% to 40%.

The agglomerates according to the prior art from the Verbren residues in the cake during the filtration of beer or wine retained organic ingredients show no acceptable basicity. The agglomerates of the present invention are obtained without calcination and their pH is acceptable. Their water needs are between 8 and 12%, their usable storage Water is 20 to 40% and their structural stability is between between 80 and 95%. Those who have a water requirement between 8 and 12% are particularly suitable for hydroponic crops themselves if their usable storage water does not exceed 12%. Those, the need for water between 8 and 12% and a usable Spei are between 20 and 40%, are for pot plant cultivation suitable where a resistance of plants regarding  the unavoidable hydrological stress conditions, e.g. During their transport or storage.

Without departing from the scope of the present invention form These products equally absorbents to oil, for example on the garage floor, to absorb.

Example 1 (prior art)

One makes a carrier material for plants with a binder Sound according to the description of the above-mentioned DE-PS 31 20 782 ago. For this you mix a wet filter cake from a brewery with a bentonite clay (CLARSOL® FR4 from CECA S.A.) with Car boxymethylcellulose to the water during extrusion withhold. The composition used is the following:

Filter cake (dry): | 1000 g Water: 650 g bentonite: 100 g carboxymethylcellulose: 20 g

After kneading in a WERNER kneader and after extruding a diameter of 1.6 mm by means of a Pinette press is the The product is oven-dried and the strands are lengthened cut by 5 mm.

The properties are the following:

• - a water requirement of 5%
• - a usable storage water of 30%
• a free air volume in the carrier material of 30 to 35%
• - a pH of 6 to 7
• - a mechanical resistance after light together to press  
• - a structural stability of approx. 60%
• - a very high permeability.

However, structural stability and water retention are not reaching for use as a carrier material for hydroponics. It can be improved by calcination at 600 ° C, the clay-containing binder is sintered and the organic components be destroyed by the calcination; but the structural stability stays below 65% and the pH rises to 8.9. These products allow plant growth in the lab, but the Aussal fines due to poor structural stability makes them, because of the pollution of the recirculation systems of the Nutrient solutions, unusable.

Example 2

The filter cake of Example 1 is made with the same bentonite clay mixed and then compacted under 50 bar. The product will dried, crushed and to a size between 1 and 4 mm sieved. The composition used is as follows:

Filter cake (dry): | 1000 g Water: 650 g bentonite: 100 g

The properties obtained are as follows:

• - a water requirement of 5%
• - a usable storage water of 25%
• a free air volume of 30-35% in the carrier material
• - a pH of 6.5
• - a mechanical resistance to weak compaction th
• - a structural stability of about 50%
• - a very high permeability.

After calcination at 600 ° C to obtain:

• - a water requirement of 4%
• - a usable storage water of 27%
• a free air volume of 30-35% in the carrier material
• - a pH of 9
• - a mechanical resistance to medium-thick compaction th
• - a structural stability of approx. 60%
• - a very high permeability.

This material has the disadvantage of a very weak structural Stability.

Example 3

One proceeds with a compaction between 50 and 400 bar of the previous filter cake, but without using the clay-containing Binder. The composition consists of:

Filter cake (dry): | 1000 g Water: 650 g

the water from the filter cake after a partial drying comes.

After simple drying, very friable granules are obtained following properties:

• - a water requirement of 1%
• - a usable storage water of 15%
• a free air volume of 30-35% in the carrier material
• - a pH of 6
• - a mechanical resistance to very low density tung  
• - a structural stability of about 10%
• a very weak permeability due to the crumbling of the Product.

These granules are unusable as a carrier material for crops. you decompose quickly into a mud in which the plants are on rotten due to lack of air at the level of the roots.

Example 4

The bentonite clay of Example 1 is replaced by attapulgite (CLARSOL® ATCNA from CECA S.A.). This gives a dried Product with the following characteristics:

• - a water requirement of 4%
• - a usable storage water of 30%
• a free air volume of 30-35% in the carrier material
• - a pH of 6
• - a mechanical resistance to weak compaction th
• - a structural stability of about 70%
• - a high permeability.

After calcination at 600 ° C, the following properties are obtained:

• - a water requirement of 5%
• - a usable storage water of 29%
• a free air volume of 30-35% in the carrier material
• - a pH of 8.1
• - a mechanical resistance to mediocre compaction tung
• - a structural stability of about 75%
• - a high permeability.

Example 5

A granule composition according to the invention is with the sliding chen filter cake as in Example 1 by agglomeration with a Carbamide / formaldehyde resin (Caurite® from ELF ATOCHEM S.A., a resin in aqueous composition with 33% water), according to:

Filter cake (dry): | 1000 g Water: 650 g Carbamide / formaldehyde resin: 450 g Catalyst NH₄Cl: 4.5 g

The product is extruded through a Kahl press and at a Temperature between 95 and 180 ° C dried to ver the resin networks. Then it is crushed to a size of 1 to 4 mm. The Granules have the following properties:

• - a water requirement of 12%
• - a usable storage water of 25%
• a free air volume of 30-35% in the carrier material
• - a pH of 5.5
• - a mechanical resistance with heavy compression
• - a structural stability of about 95%
• - Due to the granulation, a high permeability of 27 Darcy.

The content of heavy metals in the granules was analyzed and compared with the permitted values according to NFU 44-041:

The heavy metal content of the granules is in agriculture soil or in sewage sludge for the farmer sheep manure is allowed, compatible. A content of heavy metals above this standard prohibit any use for hydro cultures or pot plant cultures.

100 g of this product absorbs 110 g of water or oil. These Property can be used to create liquid puddles in the house or to absorb in industry, for example on garages floors.

It should be noted that the water requirement when using 150 g Caurit resin is 15% while the structural stability is around 35% drops. With 300 g of Cauritharzes the water requirement 12% back, but the structural stability is then 55%, im Contrary to the desired 80 to 95%. At over 550 g of cau ritharzes, the cost price is too high, and the water requirement decreases to about 8% without sacrificing structural stability  improve. The products, made up of 45 parts caurite resin, based on 100 parts of the filter cake, are produced, are economical and optimally suited for hydroponics.

These products can be easily recovered after drying be moistened.

Example 6

The above experiment is carried out with a non-calcined, dried and ground diatomite instead of the filter cake; when Binder is a carbamide / formaldehyde resin used. In front Drying gives granules having the following properties:

• - a water requirement of 1%
• - a usable storage water of 9%
• a free air volume of 30-35% in the carrier material
• - a pH of 5.8
• - a mechanical resistance after heavy compression
• - a structural stability of about 90%
• - a high permeability.

These granules are uninterest as a carrier material for hydroponics although in some respects it is the product of Example 5 resemble. Due to a water requirement of 1%, a product is 12 times less efficient than that of Example 5, at substantially same production costs.

Example 7

The granules are made from a filter cake from a brewery (not calcined) and CPJ55 cement having the following composition manufactured:

Filter cake: | 1000 g Water: 500 g Cement CPJ55: 300 g

The granules are extruded through a Kahl press, then on a size between 1 and 4 mm shortened. They show the following Properties:

• - a water requirement of 5%
• - a usable storage water of 35%
• a free air volume of 30-35% in the carrier material
• - a pH of 9.6
• - a mechanical resistance after heavy compression
• - a structural stability of about 30%
• - a high permeability before crumbling.

These granules of cement are due to their low structural Stability and its increased pH as a carrier material for plants not useable.

Claims (9)

1. support materials for plants whose

• - water consumption is at least 8%,
• - air volume in the bulk volume of the carrier material is more than 20%,
• - structural stability is more than 80%,
• pH is between 3.5 and 8,
• Permeability is more than 15 Darcy, preferably more than 25 Darcy,

those from strands of a carbamide / formaldehyde resin and kieselguhr are formed. 2. carrier materials for plants according to claim 1, characterized net, that they are based on 100 parts diatomaceous earth 20 to 50 parts (dry) Carbamide / formaldehyde resin included. 3. Process for the production of carrier materials for plants Claim 1 or 2, characterized in that wet pebbles gur with a carbamide / formaldehyde resin kneading an acid contains, and that one processes it into strands and that one this dries at a temperature between 95 and 180 ° C. 4. The method according to claim 3, characterized in that the off kieselguhr consists of previously calcined kieselguhr, whose permeability is between 0.030 and 15 Darcy. 5. The method according to claim 3, characterized in that the off starting material of kieselguhr from a filter cake from the brewery or viticulture. 6. Use of a granulate according to claim 2 for hydroponics.   7. Use of a granulate according to claim 1 or 2 for potted plants crops whose usable storage water additionally accounts for more than 20% is. 8. Use of a granule according to claim 1 or 2 for absorption liquid, aqueous or oily puddles in the household or in the Industry.