FI111940B - Process for the preparation of organic mineral grains - Google Patents

Description

111940

A process for the preparation of organic mineral granules

The invention relates to a process for preparing an organic mineral fertilizer from an organic material using a dry granulation method of solid with urea 5. The invention provides a fertilizer product having good mechanical properties.

The use of nitrogen-containing natural materials generates huge amounts of natural waste and its disposal is a problem. Most of this waste material is in a form that generally cannot be used commercially in agriculture. This waste-10 material includes waste and by-products from livestock production, rearing and breeding, from livestock to sludges recovered from waste water treatment plants.

The use of these nitrogenous natural waste materials as fertilizers in agriculture has been the subject of great interest. Typical fertilizer products have been prepared by composting, extruding, pressing, pelleting or adding them to resin agglomerates and a few granulation processes.

US 4,832,728 discloses a process for preparing a fertilizer from melamine and urea. JP-A 7157385 discloses a process for preparing fertilizers! '*'; A method in which calcium cyanamide, in addition to urea, is the main ingredient of the fertilizer. Li-; ': 20 however, it may contain some organic fertilizer, the form of which, however, is by no means specified.

In U.S. Patent 5,021,077, Harmony Products Inc. describes a process .. for the preparation of agricultural granules by heating moist nitrogenous materials such as cereal by-products, hairs, feathers, fish and crustaceans, blood and bone meal and poultry waste. , in basic conditions.

'; The organic material was mixed with aldehyde compounds in the fluidized bed where the materials exhibited adhesive properties. Thereafter, the material was granulated and cured by further air drying while still heating.

Similarly, U.S. Patent 5,411,568 discloses a process for preparing a sustained release fertilizer by admixing dry nitrogenous particulate waste stored in a urea formaldehyde oligomer. First, the organic nitrogen-containing waste was dried and screened and a reactive liquid urea-formaldehyde oligomer was prepared from urea and formaldehyde. The waste and oligomer were mixed until the oligomer was uniformly distributed in the waste granules, and then an inorganic acid was added to adjust the pH and further adjust the pH to provide a slow release product. For larger, 8-6 mm granules, the crushing test showed that the particles were quite hard and required an average crushing force of 5 to 13 N to break them.

One consideration for the farmer using organic material based fertilizers is the mechanical strength and durability of the granules. They should be hard enough to withstand machine application, which is commonly used with mineral fertilizers. The required and typically achieved crushing strength 10 for mineral fertilizers is about 30-40 N.

The solid granulation method described in our previous patent application WO-A 00/00452 was developed to solve problems of granulation, product quality and storage in the manufacture of compound fertilizers. It is a process for the preparation of compound fertilizers such as N-P-K, N-K or N-P, in which solid raw materials are mixed in a mixer and fed to a granulator together with hot air. The raw materials are granulated without the addition of water or any other liquid such as ammonia, phosphoric acid or sulfuric acid. Granulation is thus really a fixed granulation method. Since no water or other liquid is added, it is not necessary to dry the granulated product. In addition, the product has good physical quality. This process has been further developed as described in our patent FI-A 19992021.

* I

It is an object of this invention to treat organic waste as fertilizer granules for industrial use. Typically, for example, composted material, when used as such, can only meet local needs, and is rarely transported very far.

The essential features of the invention are set forth in the appended claims.

The object of the method of the present invention is to provide a fertilizer based on organic waste material having good mechanical properties for use in the same way as, for example, mineral based field fertilizer.

; A novel process for producing high strength fertilizer granules based on organic waste has been discovered. It was found that the dried organic waste material before mixing can be mechanically processed into durable granules using a • solid granulation method. By heating a substantially anhydrous mixture of dried organic waste material with urea and optionally other fertilizer source materials, mechanically robust fertilizer granules were obtained that were comparable to the nutritional values of the field fertilizer.

The novel process for the preparation of fertilizer granules based on the organic waste material comprises the steps of: a) drying the organic waste material and optionally crushing the dried waste, b) mixing the dried organic waste material with dry urea and optionally other fertilizer source material and recycled material; c) feeding said solid feed to a melter and heating the feed to melt the desired 10 portions thereof and keeping said portion melted; having the desired grain size distribution.

According to a preferred embodiment of the invention, the process is carried out continuously and the molten portion of the feed is maintained in a constant state during the process by adjusting the flow rate of the feed and the temperature of the heating medium heating the melting apparatus. The optimum proportion of molten feed depends on the desired quality of the fertilizer and the starting materials used.

•

The melter is heated either externally or internally. The required temperature depends on the composition of the fertilizer feed. The walls of the melter can be heated from the outside using electric heating elements. Preferably, the hot melt air is supplied to the melter at a temperature of 300-550 ° C. As the air exits the melt-25, the temperature has typically dropped below 105 ° C. From the mixer to the melter .. * The temperature of the input feed is 30-60 ° C.

The temperature of the partially molten feed leaving the melter is suitably 70-110 ° C.

The organic waste materials that can be used in the present invention are; * for example, composted animal faeces, pig, cattle or poultry manure, 30 composted slaughterhouse waste, recovered sewage sludge, cereal by-products or peat, preferably pig or cattle manure. Organic waste material is dried to a water content of less than 10% before being used. If desired, the material may be crushed to a particle size of less than two or one millimeter, depending on the desired size of the product.

4, 111940

The dry urea used in accordance with the invention may be of various grades, for example in powder form or in the form of beads. The amount of urea to be mixed with the organic waste material is at least 40%. If no other fertilizer feedstock is used, the urea content can be up to 80%.

In a preferred embodiment of the method, other solid fertilizer raw materials may be used to control the nutrient value of the fertilizer and the final composition of the fertilizer. For example, diammonium phosphate (DAP), monoammonium phosphate (MAP), crude phosphate, potassium chloride (MOP), potassium sulphate (SOP), standard superphosphate (TSP), ammonium sulphate (AS) and am-10 monium chloride may be used.

Prior to delivery for sale, the granulated product is screened to obtain fertilizer granules of 2-5 mm size. The size of the granules may vary according to the needs of the customer. The amount of non-screen granules is small, less than 2% for granules greater than 5 mm, and the same for granules less than 2 mm. Unsized ma-15 material (<2 mm) and oversized material (> 5 mm) obtained by screening can be recycled as said recycled material. The oversized material can be milled after screening before recycling, if desired.

The melter and granulator may be separate units, but the melter and granulator may also be part of the same apparatus.

* '· * 20 The finished granulated product has a low water content, less than two or one percent by weight, depending on the quality, and is derived from the source material. This water content is:, i .: low enough, the product does not need to be further dried as in methods where water or other liquid is added to the fertilizer mixture before or during the granulation. In the process of the invention, the water is evaporated by the heat of crystallization released from urea.

The process according to the invention provides granules of excellent integrity and good mechanical properties. The crush strength of the granules is at least 25 N, which is very important in view of the large-scale agricultural use of granules with granular spreading machines. The product has very good abrasion resistance and fragmentation, less than 0.5% and less than 30%, respectively.

: * Various types of fertilizer can be produced by the method according to the invention. The size depends on the source material used. When only urea and composted livestock manure is used, an N-type fertilizer is obtained. Different types of N-K or N-P-K fertilizers can be obtained, depending on the amount of other 5111940 feedstocks in the fertilizer and the quality of the organic waste material.

An advantage of this invention over other methods of granulating organic waste based fertilizers is that the materials can be granulated without the use of additional moisture or water or other liquids such as inorganic acids. Therefore, an expensive granule drying step is not required. In addition, the granules of the present invention are of good mechanical quality, allowing large-scale machine application.

The following examples illustrate the invention in more detail.

Example 1

The organic waste material consisting of composted pig and livestock manure, the chemical composition of which is listed in Table 1, was dried to a moisture content of 5.6% as determined by the Karl-Fisher method. The dried composted material was crushed to a grain size less than 1 mm using an Atrex mill.

A mixture of 52% urea, 18.2% MAP (Russia, crushed), 15.8% KCl (K20 60%) and 14% dried and crushed compost material was prepared.

The mixture was fed to a table mixer at a rate of 3.18 kg / h and circulated at a rate of 0.8 kg / h. The mixture was maintained at 97 ° C by supplying heated dry air, the temperature was 460 ° C. Thawing and granulating were performed mainly in the granulating drum and partly in the condenser. The inside temperature of the condenser was 31 ° C and the temperature of the granules leaving the condenser was 26 ° C.

Table 1. Composition of Composted Source Material [Water 27.8%

Solids_71.7% _

Total Carbon_21.4% _

Total nitrogen_2,6% _ f NH4-N_0,5% _

Total-P2Q5_4.2% _

Total K2Q_3.9% _%: The fertilizer product thus obtained was coated using 2 kg / ton SK Fert FW5 and 25 3 kg / ton talc.

6111940

Example 2

The chemical and physical properties of the fertilizer prepared according to Example 1 were determined.

Table 2 shows that the soluble phosphorus content was about 60% and that the product 5 had an N-P-K ratio of 23-8-10 which is suitable for field fertilizer.

Table 2. Chemical analysis of the fertilizer product

Water 0.34%

Total-C__17.4%

Total-N__23.4%

Urea-N__21.6% NH4-N__1.7%

Total-P2Q5__8.2% NAC-P2Q5__7.9% WS-P2Q5__4.9% K20__10.6% pH 5.6% After the condenser, the product had a grain size of 29% between 5-2.5 mm, which indicates a moderate granulation effect. Screening analysis of the product (Table 3) showed that: · 99% of the material had a grain size of 5-2 mm. No caking in U-bag: *; now and the crushing strength was good. These characteristics fill the field spreading machine; ;. operating requirements, which are essential for the farmer.

Table 3. Physical properties of fertilizer granules t ·, ”. Screening Analysis (%) + 5 0 -5 + 2 99 '> -2__1_

Caking in U Bags__0_

Granule Crushing Strength (N) __ 27_

Friction (%) __ 0 ^ 4_

Fragmentation Strength (%) __ 28_ 'CRH (%) __ 16

Moisture absorption at 80% relative humidity: 2 h (%) 3.8 4 h (%) 6.9 6 h (%) _ 9.6 111940 7

Example 3

Fertilizer granules were prepared as in Example 1 but using a composition of 48% urea, 16.9% MAP (Russia, crushed), 14.7% KCl (K20 60%) and 20% dried and crushed composted material.

Granulation was also good in this case, but the grain size distribution was reduced to about 18% using a 5-2.5 mm sieve, indicating that the power was lower than in Example 2.

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Claims (10)

111940 1. A process for the preparation of high strength organic mineral granules from organic source material such as animal manure, slaughterhouse waste, sewage sludge, cereal by-product or peat, by solid granulation, the method comprising heating the melt and feeding the desired portion thereof, and keeping said portion melt, feeding the partially melted feed from the melter to the granulator to obtain a granulated product, and cooling and screening the granulated product to obtain dry fertilizer granules having the desired grain size distribution, other solid source materials contain at least organic waste material that is dried to less than 10% moisture content before mixing with solid source materials working with each other. Method according to Claim 1, characterized in that the organic waste material is further crushed before mixing the solid source materials. Method according to claim 1 or 2, characterized in that: ·. ·. The method is implemented as a continuous process. Method according to any one of claims 1 to 3, characterized in that: '. i .: that the organic source material in the solid feed is less than 30%. ··. A process according to any one of claims 1 to 4, characterized in that the urea content is at least 40% of the total amount of solid feed. t Method according to any one of claims 1 to 5, characterized in that 'the feed is heated to and maintained at a temperature of 70 to 110 ° C' to ensure that the feed remains in a partially molten state. Method according to any one of claims 1 to 6, characterized in that the solid feed contains other fertilizer source materials selected from the group consisting of monoammonium phosphate (MAP), diammonium phosphate (DAP), potassium sulfate (SOP), potassium chloride ( MOP), crude phosphate, standard sulfate phosphate (SSP), triple superphosphate (TSP) and ammonium sulfate (AS). 111940 Method according to any one of claims 1 to 7, characterized in that the organic source material contains composted animal faeces, peat, slaughter waste. Method according to any one of claims 1 to 8, characterized in that the organic source material preferably contains composted cow and pig manure. Method according to any one of claims 1 to 9, characterized in that the undersized and oversized material obtained from the screening are recycled and, if desired, the oversized material is ground after screening. 10 Paten tkrav