Abstract: A process for the conversion of organic agricultural waste into a soil amendment uses earthworms. The organic material is rent into small pieces, placed in a rick with 60% or more moisture. Earthworms are added to the rick for the consumption of the decomposing organic material. Succeeding ricks are added as the material is being consumed until the resulting castings can be most efficiently separated from the earthworms and remaining organic material. Storage as silage of the organic agricultural material may be employed between harvesting and addition of the earthworms.

Abstract: The present invention relates to an agricultural fertilizer prepared from animal waste, rock fines, and optionally other ingredients to improve its performance. The process for preparing this fertilizer is within the scope of this invention.

Abstract: A method of preparing a dried fertilizer composition from poultry manure, minimizing decomposition and degradation of organic nitrogen, to achieve a total nitrogen content of about 3 to about 7 percent by weight.

Abstract: A method of processing fibrous waste materials, such as textile waste, in which the waste materials which are not particulate are formed into particles, and the particles are thoroughly mixed to form a waste mixture. The waste mixture has an increased temperature which allows the mixture to be used as a heat source as well as a plant growth medium. A particulate source of calcium may be added to the mixture if it is to be used as a plant growth medium. The plant growth medium may be mixed after formation with a dry wood waste mixture to enhance both its growth and heat properties.

Abstract: The present invention provides a process of decontaminating soil and/or sediments containing DDT type contaminants by converting these contaminants into harmless materials thereby decontaminating the soil to whatever extent desired, either partial decontamination or complete remediation.

Abstract: The present invention provides a process of decontaminating soil and/or sediments containing DDT type contaminants by converting these contaminants into harmless materials thereby decontaminating the soil to whatever extent desired, either partial decontamiation or complete remediation. The process comprises treating solid and/or sediment which contains populations of viable anaerobic and aerobic microbes capable of transforming DDT type contaminants into harmless materials and being viable under both anaerobic and aerobic conditions.

Abstract: A sulfur-based, chemical soil-corrective or conditioner for agricultural use in the form of pellets, said product containing fly sulfur powder, at least 3% by weight of an inert compound selected from the group consisting of clay, bentonite, kaolin and mixtures thereof, and at least 0.5% by weight of a wetting agent; said components are mixed with one another, then subjected to wet extrusion and next to drying, so as to obtain mechanically strong pellets which are porous and suitable to be very easily disgregated when they are in contact with soil moisture.

Abstract: A process for the treatment of porcine excrement, to transform it into fertilizer. To a liquid solution of porcine excrement, a solution of phosphorus pentoxide and potassium oxide is added in suitable proportions to obtain in the final product the desired ratio between nitrogen, phosphorus and potassium, and as a function of the nature of the soil and of the type of application, after which the obtained solution is mixed with a product adapted to retain water, having the desired shape of the final product, so as to obtain a shaped and conditioned fertilizer, which is subjected to a drying treatment. Preferably, the water-retentive product is in the form of granules of polyacrylamide, which swell in water to a number of times their size when dry. The granules absorb the liquid very quickly but release it only slowly, so that they can swell and dry over and over and so have a long effective life.

Abstract: A process includes the steps of: introducing, in a sequential manner and at a predetermined frequency, a substrate of organic waste substances by loading from above inside at least one cylindrical container of circular, polygonal or other cross-section having a vertical axis and at least one transverse horizontal dimension of which is small, in other words of the order of 1 m or even less, the vertical walls of which are at least partially made from a non-gastight material, such as a porous or aerated material; introducing into this pile or windrow lumbricids which will climb upwards; withdrawing, in a sequential manner and at a predetermined frequency, the lower substrate layer of previously lumbricid-composted organic material, this withdrawal causing the substrate to be lowered sequentially, under gravity, at a speed at most equal to that at which the lumbricids climb; and, removing the substrate of previously lumbricid-composted organic material.

Abstract: A process for forming a microelement deficiency-corrector comprising a mixture of trace elements, in hydrated sulfate form, optionally containing carbonates and including iron, magnesium, manganese and zinc, with the following typical elemental analysis: Magnesium 3.5-6%; iron 12-19%; Manganese 11.5%; zinc 0.2-0.3% and organic matter 0-45%.The process comprises mixing 50-95% of the by-product of manufacture of titanium bioxide via sulfate, 5-10% alkaline earth carbonate or magnesite and, optionally, 10-45% organic matter, grinding the mixture, granulating it and drying it, cooling it and screening it.The corrector is used in agriculture to prevent and control ferric chlorysis, to favour physiological processes of harvests in which iron takes part and to avoid deficiencies of manganese and zinc farmland.

Abstract: This invention is a method to produce a substitute for peat moss comprising:mixing in a mixer adsorptive cellulosic material with an effective amount of an inoculum containing cellulose degrading microorganism such as lignin cellulose degrading bacteria upon anaerobic fermentation and manure municipal waste or similar waste, manufactured feedstock or a blend of these,transferring said mixture to a chamber,allowing the temperature of said mixture to rise in said chamber until said cellulosic material changes color, thenaerating said mixture to remove water vapor, ammonia and other gases in an exhaust gas and then removing said mixture from said chamber for use as a substitute for peat moss and other uses.

Abstract: Solid waste such as sewage sludge containing fecal matter is processed to reduce pathogens by at least 90% and converted to a useful product such as an amendment to agricultural land by combining the waste with an acid such as concentrated sulfuric and a base such as fly ash which exothermically react and thermally pasteurize the waste and add mineral value to the product. Pozzolanic materials, such as fly ash agglomerate the product and after grinding, the particles can aerate soil. The calcium oxide in fly ash reacts with sulfuric acid to form calcium sulfate dihydrate, a soil amendment. The amount of sulfuric acid can be controlled to provide a product with acid pH which is useful to neutralize alkaline soils such as those found in the Western United States of America.

Abstract: Improved release profiles which can, for the first time, be customized to match requirements of systems including crop nutrient uptake are realized by providing a plurality of heterogeneous particles comprised of water-soluble constituents set in a matrix of water-insoluble materials, and further providing a continuous homogeneous barrier of same, or a different water-insoluble material, juxtaposed the peripheral surface of each such heterogeneous particle. A first alternate embodiment includes forming in situ reaction products to reduce the specific gravity of such heterogeneous particles. In a second alternate embodiment, there is substituted for all, or a portion of such water-soluble material, organic media comprised primarily of composted poultry litter wherein soluble iron values remain available for substantial periods of time without incorporating or utilizing expensive conventional synthetic chelating agents.

Abstract: A method for producing liquid fertilizer is characterized in that raw material made of human waste consisting of feces and urine is made to come into contact with heated animal oil, plant oil, mineral oil or a mixture of these oils under a reduced pressure, and water contained in the raw material is evaporated from the raw material and moisture made of evaporated water is collected, cooled and liquefied to produce liquid fertilizer.

Abstract: This invention pertains to a fertilizer and a process for producing the same which incorporates flyash, which is a by-product from the coal fired utility industry, with an organic fertilizing component comprising manure. The flyash and manure are mixed with the resulting mixture compressed by passing the mixture through a roller press thereby forming a sheet and then fracturing the sheet into chips or other particulate form. The water content of the mixture is controlled in an effort to produce particulates having high dry strength.

Abstract: A method of treating organic material which includes admixing organic material with water and an acid, the acid equivalent to 5-12% by total weight 100% sulfuric acid; increasing the pH of said admixture, while simultaneously introducing up to 5% by weight of steam; and heating and drying the basified admixture. The resultant material makes excellent plant food, fertilizer, or soil conditioner. Various modifications are possible, e.g., during the first step, steam may be introduced in an amount of up to 40% by weight of the final product. Also, during the first step, carbonate-free calcium may be included in the admixture of the first step. After the alkalinization step, nutrients such as lime, dolomite, rock phosphate, potash, ammonium nitrate, and/or urea may be added to the admixture. The resulting material can be granulated, extruded or pelletized.

Abstract: A high analysis suspension fertilizer containing predetermined amounts of nitrogen and other inorganic plant nutrients is produced from a low plant nutrient-containing organic material, such as animal manure or sewage sludge, by first preparing an aqueous initial suspension of the organic material by admixing with a sufficient amount of water for the organic material to be uniformly dispersed throughout the initial suspension and admixing with the initial suspension a sufficient amount of an acid, such as sulfuric acid, for reacting with the organic material and transforming it into colloidal form, the weight ratio of the acid to the total weight of the organic material in the initial suspension being within the range of about 0.2 to about 2 and the weight ratio of the acid to the total dry weight of the organic material being within the range of about 0.5 to 5.

Abstract: Fermentation products are composed essentially of poultry manure components, which products are derived from reacting poultry manure materials with concentrated sulfuric acid and calcium silicate and subsequently from fermenting the resulting reaction mixture by the use of a selected class of bacteria. The product is suitable for use as an organic fertilizer and as a soil conditioner.

Abstract: There is provided a method for manufacturing organic fertilizers by fermentation of a mixture of livestock excreement with cellulose containing organic materials, said mixture containing thermophilic and aerobic microorganisms, which method comprises adjusting moisture content of said mixture to 25-75 wt %, cutting and kneading said mixture until the temperature thereof goes up to 40.degree. C.-90.degree. C. by the elevated pressure and friction caused by said cutting and kneading, thereby causing thermophilic organisms to be activated, followed by pulverizing the thus-treated mixture while contacting it with air, thereby causing the aerobic organisms to be activated.

Abstract: A method and apparatus for making organic based fertilizer, the method including mixing organic material with phosphate, potash, or other inorganics and water if necessary. Acid is mixed with the organic and inorganic material mixture and the resulting mixture is permitted to cure for a sufficient period of time to allow the acid to chemically break down the material of the mixture. A first quantity of ammonia is then added to the mixture, and a second quantity of ammonia is added to the mixture to produce the finished fertilizer product. Quantities of the various ingredients are adjusted to provide a fertilizer that has a desired percentage make-up of the major fertilizer elements for a specific crop.

Abstract: An organic, fresh-smelling fertilizer product is produced by collecting llama pellets from llamas that have preferably been fed only alfalfa hay with grain supplements. The pellets are first dried by means of a relatively slow process that enables them to harden as pellets rather than fragment, and they are then ground to produce a particulate mass such as powder, granulates or pellet-sized particles which has an alfalfa-like scent and is a very effective fertilizer.

Abstract: The invention relates to a method of recycling contaminated soil so as to form a balanced non-contaminated soil with an increased water-holding capability. More particularly the invention combines two waste products, namely hydrocarbon-affected soil and activated sewage sludge, in order to create a useful non-waste product having high marketability. The combination, or mixing, of those waste products is done either by land farming and/or by composting. In the latter case the hydrocarbon-affected soil also acts as an insulating blanket over the compost, and that blanket itself is subsequently added into the compost after the curative process has dissipated the contaminants.

Abstract: A continuous process for the non-destructive recovery of natural nitrogenous materials as highly available particulate agricultural nutrients, employing natural materials such as poultry waste, waste water treatment sludge, alfalfa meal, hatchery waste, feathermeal, corn gluten meal and bloodmeal in a fluid bed reactor-granulator where basic natural materials are acidified to pHs of 3.0 to 6.5 and formed into hardened particulates during a retention time between 4 and 20 minutes at a temperature between 70.degree. and 120.degree. C. and discharged free of caramelization before nitrogen losses from decomposition amounts to 0.5 percent of the natural nitrogenous materials. The continuous process provides a new natural nitrogenous particulate agricultural nutrient composition free of caramelization.

Abstract: The present invention relates to a mycelial fertilizer that is characterized in method, and the objects thereof are to provide a mycelial fertilizer wherein the mycelial fertilizer containing mainly thermactinomyces is carried on a specified carrier to contribute the metabolites of the thermoactinomyces and the decomposition products of the thermoactinomyces to the growth of plants as effective fertilizers in soil, and to provide a method of producing the mycelial fertilizer.

Abstract: A method and product for sterilizing and drying waste products such as plant sludge, animal excrement and process wastes wherein the waste material is first settled or dewatered to a moisture content between 4% to 60% and then blended and reacted with alkaline earth metal oxides in the presence of an atmosphere of carbon dioxide, and in the absence of the oxygen. After the sludge is blended with the alkaline earth oxides, the carbon dioxide is removed so that air or oxygen will contact the blended constituents. A violent exothermic reaction takes place between the water in the constituents and the alkaline earth oxides causing a rapid rise in temperature of the constituents and thus sterilizing the constituents to produce a safe and useable end product.

Abstract: A method for recovering volatile, organic compounds from manure, by:i) acidifying and concentrating the manure;ii) condensing the formed vapor; andiii) separating the volatile, organic compounds from the condensate.Preferably the volatile, organic compounds are removed from the condensate by liquid extraction, crystallization, distillation and/or ion exchange.

Abstract: A composting method is disclosed for accelerated decomposition of organic matter. The organic matter is deposited into a chamber of a vessel. A ram moves through a relatively short stroke within one end of the vessel so that organic matter deposited in the vessel at one end may be moved through the chamber and discharged at the other end as a result of each successive charge of matter pushing the preceding charge forward through the vessel by the action of the ram. An optimum range of compaction density for the particular organic matter being processed is determined. Also, an angle of disposition for the vessel relative to the horizontal is established for the particular organic matter being processed. This angle of disposition is established so as to cause the amount of compressive force necessary to move the organic matter through the vessel to be such as to achieve the optimum range of compaction density.

Abstract: A method for treating manure including the drying of manure by displacing water out of the manure by a carrier liquid, extracting the carrier liquid by evaporation and purifying the carrier liquid vapor for re-use, wherein fats originally present in the manure are released as manure fat, by burning the manure fat in a controlled manner and at least partially using energy thereby released in the process.

Abstract: The invention relates to a method for preparing a granular fertilizer from manure, comprising the steps of:i) acidifying the manure;ii) dehydrating the acidified manure and evaporating the carrier liquid; andiii) forming granules from the fertilizer obtained. Preferably the manure is acidified using a mixture of nitric acid and sulphuric acid, wherein in the mixture the nitric acid to sulphuric acid ratio is 30-50:70-50. The granulate comprises:______________________________________ NH.sub.4 --N 1-3% by weight NO.sub.3 --N 1,5-3,5% by weight N-total 5-9% by weight P.sub.2 O.sub.3 -total 2-5% by weight K.sub.

Abstract: The present invention relates to a method for valorizing liquid manure from pigs by elaboration of biological amendments, said method comprising the fermentation of a biomass based on a mixture of pig liquid manure and a carbonaceous medium. Said biomass is seeded by a bacterial selection comprising Serratia and Klabsiella also relates to a device for implementing such method.

Abstract: This invention is a mixed horticultural medium consisting essentially of natural zeolite particles, which has a unique property of capturing ammonium ions, and has a high nitrogen content as compared with conventionally available horticultural media thereby providing a high germentation percentage and having a nitrogen supply potential to meet requirements of plants with the aid of microorganisms in the soil.

Abstract: To produce organic fertilizer which is effective for sterile agricultural land, a mixture comprising coral reef powder, domestic animal excreta, sewage disposal waste and ground cellulose derived from plant fiber is prepared and it is well mixed in the presence of organic compounds and inorganic salts. Thereafter, it is subjected to cultivating in a multi-bath type cultivating bath for a predetermined period of time while temperature and pH are adjusted properly. Cultivation is achieved with the addition of bacilli including nitrogen fixing bacillus such as Azotobactor vinelandii, Bacillus megaterum, Rhizobium leguminosarm or the like, Trichoderma virde acting as raw fiber decomposing bacillus, candida utilus acting as yeast fungus and green algae, each of which is cultivated under the operating condition of symbiosis cultivation. The pH in the cultivating bath is maintained in the range of 5.5 to 7.5, preferably in the range of 6 to 7.

Abstract: The present invention relates to a high rate method for combining waste materials to produce valuable products for agricultural, horticultural, sylvicultural or public use. Specifically, the present invention combines the steps of alkaline stabilization, beneficiating and pelletizing waste materials, such as wastewater treatment plant sludge or animal excrement and reaction with carbon dioxide, to thereby convert the waste materials to useful products such as soil conditioners or fertilizer supplements.

Abstract: In a method and device for drying and conditioning poultry manure or similar pasty materials in the form of particles, selective micro-organisms are, in a microbiological phase, fixed onto stable moulded carrier element, added to the past material to be treated, optimum climatic conditions being generated with air conditioned for the activity of the micro-organisms. Released heat as well as water vapor are evacuated. In the case of a temperature drop, the microbiological phase is substituted by an air stream drying which is terminated when the desired dessication degree is obtained. The device comprises a closed cylindrical tank (1) wherein there is arranged a suspended mounting which may vibrate vertically and which is comprised of two cylindrical coaxial air-tight mantels (14,15) between which are distributed the carrier elements for the selective microorganisms.

Abstract: Particulate nutrient material for use as fertilizer or animal feedstock is produced from absorbent paper shreds or particles, for example of newsprint, impregnated with animal manure--for example as a result of use of the paper as bedding for chickens. The impregnated paper shreds or particles are compacted and pelleted, and may be mixed with superphosphate and/or fishmeal before pelleting.

Abstract: To prepare an effective potting media from waste plant products, a mixture of high carbon and high nitrogen organic material is mixed with a phosphoric acid solution to maintain a pH of between 5.5 and 7.1 under aerobic conditions, with or without soil. Ground wheat straw or other high carbon plant materials and ground alfalfa hay or other high nitrogen plant materials are used in the preferred embodiment in ratios of between three parts ground wheat straw or other high carbon plant materials for each seven parts of ground alfalfa hay or other high nitrogen plant materials to seven parts ground wheat straw or other high carbon plant materials for each three parts ground alfalfa hay or other high nitrogen plant materials. The mixture of wheat straw and alfalfa hay has a pH in the range of 7.0 to 8.1. Phosphoric acid 0.04 M is added periodically for approximately one month if the pH of the mixture is higher than desirable for the plant type.

Abstract: The invention relates to a novel fertilizer and method wherein a complex humic acid fertilizer is formed a mix of a select organic material, water, and measured amounts of major inorganic elements of nitrogen, phosphate, potash and sulfur. The constituents mixed in a sealed reactor system with a first material, usually an acid, are hydrolyzed by a drastic pH change, raising the mix temperature and pressure, and the mix is subsequently blended with a second material of an opposite pH to the first material, usually a base, reacting with the mix to provide a further temperature and pressure increase, to alter the pH to that of the finished fertilizer, which humic acid fertilizer is then dried and granulated or liquefied to a pumpable slurry.

Abstract: In order to reduce the volume increase of liquid manure during its storage, a process is proposed for the treatment of liquid manure in which at least one copper electrode and one counter-electrode are placed in the liquid manure, and copper ions from the copper electrode connected as the anode are introduced into the liquid manure by the application of a DC voltage which is preferably below the gassing voltage of the liquid manure.

Abstract: A clay-breaking and fertilizing composition comprises a finely ground mixture of chicken manure, muriate of potash and a rock phosphate having a high limestone content and containing the phosphate in the form of the basic tricalcium diphosphate. When spread on heavy, clay soils or compacted ground and watered, the composition breaks up the soil and fertilizes it such that, after two to three months the soil is friable and immediately ready for crop cultivation. The composition is also usable in a stratified cultivation bed, particularly for desert reclamation, comprising an impermeable tank, a bottom layer of wood or stone chippings which can be supplied with water, a perforated plastics sheet covering the chippings and a top layer of growth medium comprising the above fertilizing composition mixed with sand.

Abstract: A new method for preparation of organic compost by incorporating zeolite into excretions from domestic animals. In the method, zeolite of about 10 to 30% relative to the total weight of excretions is homogeneously mixed and then piled for a predetermined period so that the water content of a surface portion of the pile of the mixture decreases to about 25% by weight or less, and the average water content of the entire pile decreases to about 55% by weight or less. The piled mixture is then supplied to a fermentation vessel in which it is scooped and turned over such that a high water content portion inside the low water content surface portion is divided into small masses and the low water content surface portion is divided into fine powders, so that the fine powders are spread around the small masses to thereby achieve effective aerobic fermentation in the vessel.

Abstract: A plant consisting of modular elements for reducing organic wastes by degrading them by means of earth worms, comprising a tank for organic wastes, arranged outside the plant assembly, an inclined main screw feeder for lifting the materials onto work stations and discharging them onto horizontal screw-feeders arranged at any work station, the horizontal feeders conveying the materials to horizontal conveyers which discharge them into modular containers arranged on the work stations, whereby, at the end of the transformation, the material is discharged through hoppers onto conveyors arranged at the plant base and conveyed to storage containers.

Abstract: This invention relates to a method of producing protein-rich forage or nitrogenous fertilizer as a commercial product from fowl droppings, swine dung, cow dung and the like by charging said ordure into a heated animal, fish or vegetable oil, subjecting the mixture to a smooth dehydrating treatment under the two-step reduced pressure conditions starting initial by with a limited pressure reduction and later increasing the degree of pressure reduction, and thereafter squeezing oil out of the treated mixture to thereby produce said forage or fertilizer. Said method is conducive to the prevention of malodor pollution caused by said livestock excrements and can also eliminate the wasteful use of fuel required in the incineration treatments.

Abstract: The invention relates to a new method for increasing the biological value of manures, dung-waters, organic wastes and/or soils rich in lysine. According to the invention manure, dung-water, an organic waste and/or soil rich in lysine, either of natural composition or supplemented with lysine, a lysine source and/or one or more agricultural chemical(s), is treated with at least 0.01 mole of formaldehyde or an equivalent amount of a formaldehyde source, calculated for one mole of free or bound lysine present.The treatment according to the invention results in a significant increase of plant growth and crop yield.

Abstract: The present invention is a method of preparing artificial fertile soil from pulverized material such as sawdust or wood chips by the utilization of biological mass production techniques. In the steps for converting the pulverized woody material into fertile soil, four-footed livestock such as cattle are raised thereon, followed by the addition thereto of crushed animal carcass residues, the breeding of earthworms therein and, finally, the raising of domestic fowl such as chickens thereon.

Abstract: A process and apparatus for producing compost having a high nutrient value from a mixture of moist, at least partially particulate organic matter containing aerobic bacteria. The composter has two parallel shafts (24,26) with radially projecting fingers (38) which, when the shafts are rotated, slowly and gently churn and agitate the mixture in the composting chamber (10) while air is directed therethrough at a predetermined low rate. When the composting action is completed the compost is promptly dried and packaged in moisture impervious containers.

Abstract: A method and composition for the elimination and control of ammonia odor from organic waste materials by contacting the waste material with a composition containing a deodorizing agent which produces a non-odorous ammonia salt, thereby eliminating gaseous ammonia from escaping into the air. The present invention also eliminates additional odors resulting from putrefaction due to ammonia fixing bacteria.

Abstract: Self-propelled windrowing apparatus having a forward material treatment housing carrying an elevating structure formed as a drum carrying a plurality of pivotal flails. The flails serve to shred and aerate biodegradable waste and elevate it to a collection auger which manipulates the elevated material to a transfer conveyor mounted within the chassis of the apparatus. The transfer conveyor moves the material to a pivotal windrowing conveyor mounted rearwardly of the apparatus which serves to form symmetrical windrow piles of material.

Abstract: Method for making of solid fertilizer by separation of liquid manure into a solid and a liquid phase by means of a separating vessel, wherein the charged liquid manure at first is divided into a solid layer and into a liquid phase and from where the liquid phase is fed into a collector vessel, and whereby the solid phase is separated. The duration time of the liquid manure in its resting stage is delayed until the layer formed by the solid phase is separated on the top of the vessel and then the discharge of the liquid phase is carried out through closeable openings.

Abstract: The manure, which has been previously finely ground, is diluted (3) so as to form a liquid mixture containing not more than 4% of solid material. This mixture is fed into a bioreactor (6) of which the gas is used to feed the burner (11) of a dryer (10) in which the manure particles are dried. Before and after passage of the mixture into the bioreactor, filaments and fibres are separated (4,9). At least part of the liquid separated in the second separator (9) is recycled (13) in the initial liquid mixture. The energy of the water vapor from the drying is used to activate the bioreactor (16). The residual liquid not recycled is subjected to a nitrifying/de-nitrifying treatment (15). The residual mud may be collected (23) and mixed with the dried product, as well as the fibres and filaments eliminated. The mud, the filaments and the fibres, rich in proteins, may be used directly as foodstuff for cattle. The other residual product are appropriate for use as fertilizers.

Abstract: Microporous, fertilizing materials or compositions, retaining water and accelerating the germination and growth of plants, characterized in that they are composed of a hydrocarbon base containing asphaltenes modified by an oxidation agent producing a liberation of gas, directly, or indirectly, in combination with at least one mineral compound reacting in acid medium, to which materials or compositions it is possible to add, by simple mixing, appropriate common manures, oligo-elements and fertilizers.Method of preparation of fertilizing materials or compositions, characterized in that a non-acid oxidizing agent is mixed with a molten hydrocarbon base in a proportion of 25 to 50% by weight with 5 to 10% of a mineral compound, the mixture is kept for 5 to 7 hours at 180.degree.-250.degree. C., poured into metal trays, cooled, ground and screened into granules of a diameter ranging from 1 to 3 mm.