GB2164640A - Coating, binding and sealant materials for fertilisers and other substances - Google Patents

Abstract

Palm oil and derivatives and by-products of palm oil are used as coatings, binders or sealants for fertilizers, such as urea, and for other substances, such as foodstuffs, medicines or chemicals for human or livestock consumption. In the case of urea, the coating preferably contains a urease inhibitor. The by-product may be sludge oil, acid oil, stearin, olein, fatty acid distillate or palm fatty acid.

Description

SPECIFICATION Coating, binding and sealant materials for fertilizers and other substances The present invention relates to coating, binding and sealant materials all derived from palm oil and derivatives and by products thereof such as sludge oil, acid oil, stearin, olein, fatty acid distillates, palm fatty acids and compounds derived from palm oil.

According to the present invention, there is provided a substance having associated therewith, as a coating and/or binder and/or sealant therefor, a material comprising palm oil and/or a derivative of palm oil and/or a by-product of palm oil.

According to a preferred embodiment of the present invention, there is provided a process of coating urea and other fertilizers and incorporating chemicals such as urease inhibitors and minor elements to urea and fertilizers by the coating and binding action of palm oil or its derivatives or by-products such as sludge oil, acid oil stearin, fatty acid distillates, palm fatty acids and compounds derived from palm oil.

The use of the binder (having a melting point of, for example, 50"C) obviates the need to melt the urea at a high temperature in order to incorporate the chemical and is an advantage if the chemical to be added undergoes any change of property at the melting temperature of urea (melting pint 140"C).

Preferably, the coating and binding materials are used to bind two or more substances including micro-organisms such as bacteria, fungi, mycorhiza and other inoculants as given in one example whereby an urease inhibitor is added to urea and other example whereby the various ingredients of a bait are held together.

Preferably, the process is applicable to food stuffs, medicines and chemicals for human and livestock consumption wherein the materials are used for the purposes of coating, binding and sealant. Palm oil and all its derivatives and by-products are edible.

Preferably, the process is applicable to pesticides and herbicides, wherein the materials are used for the purpose of coating, binding and sealing.

Some of the terms used herein will now be explained: Palm Oil. The oil obtained from the fruit flesh of the oil palm (Elaeis guineensis).

Acid oil. This is a general term used for a by-product obtained from the alkali refining of oils and fats.

During alkali refining the free fatty acids are neutralised with alkali and this soap stock containing some emulsified, neutral oil is separated. Acidification of the soap stock gives acid oil. Main components of acid oil are fatty acids, neutral oil and moisture.

Fatty acids. The products obtained when glycerol is split off from the triglycerides of fats and oils by any method of hydrolysis. Triglycerides are composed of three molecules of fatty acids and one molecule of glycerol. Since these acids are found only in natural fats and oils, the term fatty acid applies to any acid that can be obtained from natural fats and oils. After hydrolysis, 100 grams of fat yield approximately 95 grams of fatty acids. In the field of industrial usage, fatty acids are usually further classified according to the treatment to which they are subjected subsequent to hydrolysis. Natural fatty acids are straight hydrocarbon chains with an acidic carboxyl group at one end. They have an even number of carbon atoms usually between four and twenty two. The most common chain length however is sixteen and eighteen. They may have one or more double bonds in the chain.

Palm fatty acid distillate. This is a term used specifically for the by-product obtained from palm oil refined by steam distillation (physical refining). PFAD contains free fatty acid (major component) and a small amount of unsaponifiable material and neutral oil, including mono and diglycerides.

Stearin. This term refers to the solid fraction of an oil obtained by filtration or centrifugation after the oil has been crystallised at a controlled temperature. Stearins are characterised by being more saturated than the oils from which they are derived. Fractionation of palm oil yields palm stearin.

Sludge oil. This is impure palm oil recovered from sludge wastewater.

The foregoing terms are taken from "A Layman's Glossary of Oils and Fats" edited by K.G. Berger, published by Palm Oil Research Institute of Malaysia (October 1982).

In accordance with the present invention, improvements in the physical and chemical properties of urea, urea-containing and other fertilisers of various nutrient composition can be made by coating them with various concentrations of palm oil or its derivatives or by-products, and by incorporating additives such as urease inhibitors, minor elements, mycorhiza, etc. through the binding action of the coating materials.

A particular good way of carrying out the invention is to melt the coating material such as palm oil or its derivatives or by-products until they are completely liquid. The liquid coating material is then added to the fertiliser crystals, prills or granules, preferably at similar temperature and then mixed until an even coating is formed on the fertilizer crystals, prills or granules. Alternatively, the coating process can be carried out by spraying the liquid coating material such as palm oil or liquid derivative or liquid by-product on the surface of the fertiliser prills or granules or any other means by which an even coating can be achieved. The amount of coating materials such as palm oil or its derivatives or by-products used in the coating is generally in the range of 0.5% to 20% by weight based upon the total amount of fertiliser, preferably 1.5% to 12% by weight.Incorporation of additives are made by mixing them with the urea and fertiiisers and in the coating process, they are held to the urea and fertilisers by the binding action of the coating materials. Using this invention, we have carried out various tests to compare coating materials from sludge oil, fatty acid distillate and stearin with another common coating such as 30% sulphur coating supplied by a commercial company. The properties tested were the moisture absorption or hygroscopicity, solubility by leaching with water and reduction of volatilisation losses.

1. Moisture Absorption or Hygroscopicity When urea is mixed with other chemicals, its critical relative humidity is lowered leading to a very hygroscopic nature (see "Fertilizer Manual", International Fertiliser Development Center, Muscle Shoals, Alabama, U.S.A., 1979 - hereinafter abbreviated to IFDC, 1979). This is a great disadvantage in humid countries where the humidity is so high that the fertiliser granules literally break down after a few hours exposure to air. Storage becomes a problem unless the packing is air-tight and bagging is done in a humidity controlled area.

In accordance with the present invention, it has been found that coating the fertiliser with palm oil or its derivative or by-products can reduce the hygroscopicity of the urea containing fertiliser particles by acting as a sealant around the fertiliser particie and prevent the absorption of moisture. Moisture absorption tests were carried out in which 20 grams of various coated ureas containing urease inhibitors such as boric acid and hydroquinone were exposed to 86% relative humidity in a constant humidity vessel over 5 days. The increase in % moisture content (m.c.) daily is shown in Table 1.

TABLE 1 Results of moisture tests (% m.c.) on exposure of coated and uncoated ureas to 86% relative humidity % coating of fatty acid Period of exposure distillate (FAD) 1 day 2 days 3 days 4 days 5 days 2 % boric acid 0 2.2 3.7 4.1 4.8 5.9 3% 1.1. 2.1 3.1 3.8 4.9 6% 0.9 1.4 1.4 1.4 1.8 4% boric acid 0 1.9 3.3 5.3 6.3 7.9 3% 1.0 1.4 1.5 1.8 2.4 6% 0.2 0.2 0.2 0.4 0.7 8% boric acid 0 2.2 3.7 5.2 6.9 8.7 3% 0.8 2.2 3.9 4.7 5.1 6% 0.2 0.3 0.4 0.7 1.6 2% hydroquinone 0 1.6 2.7 3.8 5.0 6.4 3% 1.4 2.5 3.6 4.6 5.8 6% 1.5 2.1 3.4 4.4 5.1 4% hydroquinone 0 1.4 2.1 2.3 3.1 3.9 3% 1.0 1.4 1.6 2.0 2.5 6% 0.9 1.4 1.9 2.4 2.7 8% hydroquinone 0 2.1 2.9 3.9 4.8 6.6 3% 1.0 1.7 2.1 2.4 2.5 6% 1.4 1.9 2.9 2.6 2.9 The results show that the fatty acid distillate coating was effective in reducing moisture absorption of urea fertilisers.

With urea based NPK compounds, the critical humidity is lowered and moisture absorption is more rapid than urea alone (IFDC, 1979). Tests in constant humidity vessels using a urea-based compound containing 14% N, 6% P205, 21% K2O and 4% MgO and various degrees of coating gave the following results shown in Table 2.

TABLE 2 Results of moisture tests (% m.c.) on exposure of coated and uncoated urea-based NPK compound %coating of 80% relative 86% relative fatty acid humidity humidity distillate 1 day 2 days 3 days 1 day 2 days 3 days No coating (Control) 2.9 5.6 8.8 3.2 6.9 9.2 11/2% coating 1.9 4.5 7.2 1.8 4.0 6.3 3% coating 1.0 2.6 4.5 1.0 2.4 4.4 6% coating 0.8 1.8 2.9 0.7 1.6 2.6 Physically, the fertiliser granules start to soften and disintegrate when the moisture content reached around 5%. The results show that fatty acid distillate coating of 3% or more will be able to prevent the granules from softening over 3 days while the uncoated granules can only stand a day's exposure before crumbling.

2. Solubility in water Fertilisers that release plant nutrients slowly throughout the growing season or even several seasons are especially attractive because because of several potential advantages such as better nutrient uptake by plants; reduction of losses by leaching, fixation or decomposition, reduction in application costs through less rounds of application; elimination of luxury consumption; and avoidance of fertiliser scorching of plants. Among the soluble fertilisers, the need for a slow release nitrogen fertiliser is more acute than for phosphate or potash. It has been estimated that utilisation of nitrogen fertiliser by crops seldom exceeds 50% and may be as low as 20% under some conditions (IFDC, 1979). Losses of fertiliser N are mainly through leaching and surface drainage, volatilisation losses as ammonia and denitrification.

In accordance with the present invention, it has been found that coating the fertiliser with palm oil or its derivatives or by-products can reduce the solubility and leaching losses of the fertiliser. Referring to Figure 1 of the drawings, to demonstrate the reduction in solubility, 10 grams of ammonium chloride 1 in a filter paper held in a 6cm diameter plastic funnel 2, and having various coating thickness, were leached by 100 ml of distilled water 3 delivered from a burette 4 over 1 hour. The leachates were collected in a flask 5 and tested for ammonium-N content by distiliation to determine the percentage of ammonium chloride dissolved by water.

In the second test, as shown in Figure 2, 1 gram of urea 6 with various coating thickness was spread over 300g of dry sieved Serdang series soil 7 (Typic Paleudult; fine loamy, siliceous, isohyperthermic family) of 90 cm2 in a plastic funnel 8 (11cm diameter) giving a surface concentration of 500 kg N/ha.

Simulated rainfall equivalent to 2.5cm rain or 220 ml water was applied using a perforated bottle 9. The leachates were collected in a flask 10 and tested for urea Kjeldahl digestion to determine the percentage of urea leached through the soil. For comparison a sulphur coated urea containing 30% S was included in the test. Results of the solubility test of ammonium chloride and leaching test of urea are shown in Table 3.

TABLE 3 Results of solubility and leaching tests with coated and uncoated ammonium chloride and urea % coating of fatty % Ammomium % Urea acid distillate chloride dissolved leached No coating (Control) 78.1. 26.0 1.5% coating - 15.4 3% coating 77.0 11.8 6% coating 53.9 6.0 12% coating 39.8 2.6 Sulphur coating 30% S - 8.6 The results show that the coated fertilisers were generally less soluble and subject to lower leaching losses than the uncoated fertilisers. In the case of urea, it was notable that 6% fatty acid distillate gave better protection against leaching losses than 30% sulphur coating. The palm oil derivative acted as a coating and sealing agent in reducing the solubility of the fertiliser materials.

3. Reduction of urea volatilisation losses When urea is added to soil, it is hydrolysed to ammonia by the soil enzyme urease which is abundant wherever general microbial activity exists. In the process, any ammonia not absorbed by the soil is lost to the atmosphere by volatilisation thereby reducing the value of urea as a fertiliser.

The present invention provides an improved fertiliser composition containing urea in which the volatilisation loss is reduced. This can be effected by several ways such as (a) coating the urea prills with palm oil and its derivatives such as fatty acid distillate, (b) spreading out the urea prills evenly during application to reduce the effective surface concentration, and (c) adding urease inhibitors to inhibit the hydrolysis process.

The measurement of urea volatilisation loss is carried out under natural aeration, temperature and soil moisture in which any ammonia not absorbed by the soil is allowed to escape freely. The volatilisation loss is determined by measuring the residual ammonium N and unreacted urea in the soil after incubation and subtracting this from the initial urea N added. The loss obtained is also corrected for any N fixation by the soil (see Chan, K.S. and Chew, P.S., Volatilisation losses of urea on various soils under oil palm, Seminar on Fertilizers in Malaysian Agriculture, Malaysian Soil Science Society, 28th March 1983).

In this technique, 1 kg of sieved 2 mm Serdang Series soil (typic Paleudult; fine, loamy, siliceous, isohyperthermic family) is placed in an open plastic container of surface area = 180 cm2 and moistened with 30% water. The coated urea prills in amounts of 2 g and 0.5 g were applied on the soil surface to give effective concentration of 500 kg N/ha and 125 kg N/ha respectively. After the appropriate incubation period which were 4, 8 and 15 days, the soil was treated with 5N hydrochloric acid to convert the ammonium to ammonium chloride. The acid treated soil was dried at 400C, ground to pass a 2 mm sieve and test samples were obtained by quartering. The samples were extracted by potassium chloride and the extract was used to test the residual N in the soil.A control sample without any fertiliser addition was similarly incubated and treated with HC1 to use for correction of readings in the blank soil.

Using this technique, various tests to show the effects of fatty acid distillate coatings were carried on a Serdang Series soil (Typic Paleudult; fine, loamy, siliceous, isohyperthermic family). For comparison, a commercial urea sample coated with 30% sulphur was also tested and results of volatilisation losses are shown in Tables 4 and 5.

TABLE 4 % N losses of coated and uncoated urea from application on moist serdang series soil at urea concentration of 500 kg Nlha Treatment After After After 4 days 8 days 15 days Urea only (control) 18.4 40.9 48.9 30% sulphur coat 9.8 25.2 32.4 Fatty acid distillate 1.5% 14.6 39.5 47.5 3% 12.3 40.7 47.3 6% 12.1 38.9 48.9 12% 14.7 37.4 46.6 In terms of reducing urea volatilisation losses, the advantage of coating with fatty acid distillate is small and limited to less than 4 days after application. Over a week or so, there is no difference in volatilisation losses between uncoated urea and urea coated with fatty acid distillate.

TABLE 5 % N losses of coated and uncoated urea from application on moist serdang series at urea concentration of 125 kg Nlha Treatment After After 8 days 15 days Urea only (control) 21.5 25.8 30% sulphur coat 21.6 22.5 Fatty acid distillate 1.5% 20.3 27.3 3% 23.4 25.8 6% 23.4 25.7 12% 26.0 27.7 Compared to previous set of results at 500 kg N/ha, there is a distinct advantage in applying urea at lower surface concentrations. Insofar as coating with fatty acid distillate is concerned, the coating confers better free flowing characteristics to urea, making it more spreadable so that concentrated patches of urea which give rise to high surface concentrations are reduced.

4. Binder for urease inhibitors and other additives to fertilisers.

One of the ways of reducing urea volatilisation losses is to control the hydrolysis of urea in soils which comprises treating the soil, either before or after or simultaneously with the addition thereto urea with urease inhibitors. As it is preferable to apply urea simultaneously with the inhibitors, the addition of inhibitor is carried out by dusting the urea particles with finely ground inhibitor, incorporating the inhibitor in molten urea or by using a binder to hold them together.

In accordance with the present invention, it has been found that palm oil and its derivatives can be used as a binder to bind an urease inhibitor to urea obviating the need for incorporation in the molten stage. This is an advantage especially when heat sensitive inhibitors are used as the melting point of urea is about 140"C. The inhibition effects of some inhibitors mixed with urea and held by 3% fatty acid distillate are shown in Table 6 below. Volatilisation losses were measured by the method previously described.

TABLE 6 % N losses of coated urea (3% fatty acid distillate) mixed with various urease inhibitors incubated on moist serdang series soil at concentrations of 125 and 500 kg Nlha Type of Urea concentration Urea concentration inhibitors : 125 kg N/ha : 500 kg N/ha 7 days 14 days 7 days 14 days Urea only (control) 14.7 23.4 36.2 49.7 Sulphur coated, 30% S 10.6 17.3 18.7 35.5 Hydroquinone coated urea Added at 2% 10.1 11.8 15.6 37.1 4% 8.8 10.1 17.7 34.2 8% 5.4 10.5 9.2 30.3 Boric acid coated urea Added at 2% 13.5 15.2 15.6 36.3 4% 11.8 12.1 15.6 32.0 8% 5.4 10.1 3.7 30.4 P.P.D.e coated urea Added at 2% 4.1 5.4 6.0 28.3 4% 3.3 5.4 3.9 27.8 8% 1.1 3.7 1.2 19.1 e P.P.D. = Phenyl-phosphoro-diamidate The results show that 3% fatty acid distillate can effectively bind the inhibitors to urea to reduce volatilisation loss. These experiments were carried out by starting the soil in a moist condition (30% moisture) and progressively drying up over the 2 weeks.To check how the amended ureas behave under rainfall, rainfall simulation studies were carried out using boric acid as the inhibitor and results shown in Table 7.

TABLE 7 % N losses of amended ureas (2% fatty acid distillate + boric acid) on serdang series soil cores after 14 days incubation under various simulated rainfall conditions Coated with 2% fatty acid distillate Rainfall condition urea Urea + 4% Urea + 8% only boric acid boric acid no rain 55.5 40.3 38.1 6.5 mm after 2 days 39.4 40.0 35.5 6.5 mm after 6 days 50.6 38.1 40.9 19.5 mm after 2 days 39.9 25.0 17.2 19.5 mm after 6 days 52.3 39.4 34.9 Average 47.5 36.6 33.3 (Note: all soil cores were saturated to field capacity at commencement) The results show that urea coated with FAD and boric acid performed better than urea alone. The reduction of losses averaged 11% to 14%. The best results were achieved with an early heavy rainfall (19.5 mm after 2 days) where the reduction of volatilisations losses were 15% to 23% for the amended ureas compared with urea only.

5. Binder for rat baits.

In oil palm and cocoa plantations, rats are a major pest problem because they cause damage by feeding on the oil palm fruits and young palms and cocoa pods. To control them, baiting with a rodenticide formulated into solid rat baits is a common practice. Paraffin wax is used as a binder ot the vanous ingredients of the rat bait formulation. In accordance with present invention, it has been found that palm stearin, a derivative of palm oil which is biodegradable and edible, can be effectively used as a binder together with paraffin wax. The incorporation of palm stearin reduces the amount of paraffin wax, an expensive rat bait component, and thereby reduces the rat bait production cost. A rat bait formulation using palm stearin as a binder is shown in Table 8.

TABLE 8 Ingredients of a rat bait using palm stearing as a binder Broken maize 14.17% Prawn dust 8.33% Flour 3.33% *Palm oil meal 28.33% Amina 5.83% **Warfarin 6.67% Paraffin wax 24.17% Stearin 9.17% * replacement with broken maize ** amount depends on the desired poison level Rat baits with palm stearin as a binder is stable in storage and the storage stability evidence is shown in Table 9.

TABLE 9 Assessment of storage stability of rat bait using palm stearin as a binder Bait disintegration Insect infestation Fungal infestation Colour Odour (%) (No. of insects) % change change Months in storage SLAB *CUBE BAIT INSIDE BAIT INSIDE SURFACE BAIT SURFACE BAIT 1st month NIL 0.5% NIL NIL NIL NIL NIL NIL 2nd month NIL 0.7% NIL NIL NIL NIL NIL NIL 3rd month NIL 1.0% NIL NIL NIL NIL NIL NIL 4th month NIL 0.8% NIL NIL NIL NIL NIL NIL 5th month NIL 0.8% NIL NIL NIL NIL NIL NIL 6th month NIL 0.9% NIL NIL NIL NIL NIL NIL * The baits were broken into discrete cubes from 40 slabs of 5x5 baits with total weight of 12 kg.

Claims (7)

1. A substance having associated therewith, as a coating and/or binder and/or sealant therefor, a ma terial comprising palm oil and/or a derivative of palm oil and/or a by-product of palm oil.

2. A substance as claimed in claim 1, wherein said material further comprises a chemical or additive.

3. A substance as claimed in claim 1 or 2, the substance being a fertilizer.

4. A fertilizer as claimed in claims 2 and 3, the fertilizer being urea, and said additive being a urease inhibitor.

5. A substance as claimed in claim 1 or 2, the substance being microorganisms, or a foodstuff, medi cine or chemical for human or livestock consumption, or a bait.

6. A substance as claimed in any of claims 1 to 5, wherein said derivative or by-product is sludge oil, acid oil, stearin, olein, fatty acid distillate, palm fatty acid or a compound derived from palm oil.

7. The use of a material comprising palm oil and/or a derivative of palm oil and/or a by-product of palm oil as a coating and/or binder and/or sealant for a fertilizer or other substance.