AU621944B2 - Brown coal based fertilizer composition - Google Patents

Description

621944 OF AUSTRALIA COMMONWEALTH PATENTS ACT 1952 COMPLETE SPECIFICATION (Original) FOR OFFICE USE Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: Int. Class o .9 •r o o 0 9 0 II o I 9*9.

o o t 0 9 0 041 99 9 eoo 0 *909 o a o o 9 (1 0 *0 9 4 i St* i Name of Applicant: Address of Applicant: Actual Inventor(s) 64 Church Street, TRARALGON. VIC. 3844 S. HENG and G.J. PERRY COAL CORPORATION OF VICTORIA Address for Service: DAVIES COLLISON, Patent Attorneys, 1 Little Collins Street, Melbourne, 3000.

Complete Specification for the invention entitled: "BROWN COAL BASED FERTILIZER COMPOSITION" The following statement is a full description of this invention, including the best method of performing it known to us: 1- ;i i L_ i;'

O

la- 00 0 o oo °0 BROWN COAL BASED FERTILIZER COMPOSITION FIELD OF THE INVENTION o This invention relates to a brown coal or lignite based compound fertilizer composition and to the preparation of this fertilizer composition by the blending oo Tof brown coal or lignite with organic or inorganic Sfertilizer additives.

o 0 0 0 0 BACKGROUND OF THE INVENTION There is a wide range of straight (single nutrient) and compound (containing two or more nutrients) fertilizers available in the market. Both types of fertilizer are widely used in agricultural production throughout the world, particularly in broadacre production.

jo *2 -2- In many situations, compound fertilizers are preferred to straight fertilizers because it is convenient and economical to apply a mixture of nutrients in a single application when compared to the separate application of two or more different straight fertilizers.

Compound fertilizers presently available in the market are produced either by admixing the required proportions of existing straight fertilizers or by St reacting/combining the required quantities of nutrients 4" during manufacture in the fertilizer plant.

e 4 A different type of fertilizer is also available in the more specialized agricultural or horticultural market.

4 4 '4 These fertilizers are known as slow release or controlled 4 44 release fertilizers. The slow release products currently l available are extensive in their range, are of extremely high quality, and are very costly compared to the conventional fertilizers used for broadacre production.

The potential for slow release application in the broadacre sector is currently limited due to the high cost of the product.

Major slow release fertilizers are produced either by coating granules of fertilizers with resin or plastic or mixing granules of fertilizers with various binders.

Organic fertilizers such as urea, ureaformaldehyde and 1i '4

I

I

4r 4t 4 4. 4 4.4 444 4, i e.L 3 -(IBDU) have some element of slow release but these are mainly single nutrient fertilizers.

It is an object of the present invention to incorporate brown coal or lignite into fertilizer formulations in order to produce a range of compound fertilizer compositions which combine the benefits of organic matter and high nutrient availability. In addition, the incorporation of brown coal or lignite imparts into the fertilizer composition an element of slow or controlled release behaviour for the nutrients.

Brown coal or lignite is derived from plant organic matter tver a period of 5 to 15 million years and as such, it possesses alltthe beneficial properties of soil organic matter which are essential to soil fertility such as high water holding capacity, high porosity and excellent buffering capacity. Table 1 lists some of the beneficial properties of brown coal which promote soil fertility.

i I1 i4' 4'.

I S, 4 3 4.

4' 4t 444$t il i

I'

a4 4 L L. ii i I m P i

I

4

II

I,

C IL TABLE 1: PHYSICAL, AND CHEMICAL PROPERTIES OF BROWN COAL, Properties Remarks Effects Colour Dark colou Facilitates warming Water Holds many times Prevents drying, Retention its weight in improves moisture water (up to 70% retaining properties wet basis) (eg. in sandy soils) Cation High exchange Increases cation exchange Exchange capacities of soil and ability to hold nutrients in plant-available form Buffering Good buffering Helps maintain a uniform Action action reaction in the soil Porous High porosity Provides good aeration Nature (up to 50%) and helps develop good structure in soil Rich in Up to 68% (dry Provides stable source Carbon basis of carbon) of carbon for soil microbiological population Rich in Up to 50-70% Growth stimulant Humic Acids content properties DESCRIPTION OF THE INVENTION According to one aspect of the present invention there is provided a slow or controlled release, compound fertilizer composition comprising brown coal or lignite in binding interaction with organic or inorganic fertilizer additive(s), supplying two or more nutrients selected from nitrogen, phosphorus, potassium and sulphur, wherein said brown coal or lignite comprises between 5 and 50% by weight of the composition and is digested with acidic or alkaline material in order to change the binding properties thereof and the release rate of the fertilizer additive(s) from the composition.

KAi /-f c201 16 15micQ6,4293 2-89.1ct,4 9' I i The concept of a brown coal (or lignite) based fertilizer composition is an important one for a number of reasons. Firstly, it incorporates organic matter in the fertilizer composition which is subsequently introduced into the soil. Secondly, it facilitates the retention of nutrients in the soil through the extremely high cation exchange capacity of brown coal or lignite. Thirdly, the presence of brown coal imparts a slow release behaviour to the fertilizer composition by its agglomeration properties; nutrients are physically held and chemically retained in plant-available form by the coal which is f tnatural organic matter.

by wegh oftefriie Preferably, the fertilizer composition is in pelletized or granulated form. Preferably also, the brown o coal or lignite comprises between percent and4_" percent t L I (ii by weight of the fertilizer composition.

The fertilizer additives which may be included in (.r the composition of the invention include the known nitrogen, phosphorus, potassium and sulphur-based materials. In addition, additives containing trace elements such as iron, manganese, molybdenum, copper, zinc or mixtures thereof, can be added to supplement the fertilizer additives. In the final composition, the brown coal or lignite essentially acts as a binding material for the fertilizer additives due to its high ion exchange properties.

-S

-6- Typically, phosphorus-based fertilizer additives may be selected from superphosphates (mono, double or triple), calcium phosphate, bone or bone meal, acid-treated rock phosphate (for example, rock phosphate which has been treated with sulphuric acid) or mixtures thereof. Typical nitrogen-based fertilizer additives include ammonium nitrate, urea, ammonium sulphate and mixtures thereof, while typical potassium-based additives may be selected from potassium hydroxide, potassium chloride, potassium sulphate, potassium nitrate, potassium oxide and mixtures thereof. Other fertilizer additives may include calcium hydroxide, calcium sulphate, calcium nitrate, 10 calcium carbonate or mixtures thereof.

I Suitably, the percentage of each of the fertilizer additives o o I o such as nitrogen, phosphorous, potassium and sulphur-based materials in the I compound fertilizer composition may range from 0 percent to 20 percent by weight, however the precise content of these fertilizer additives in the final composition may be varied according to the desired application or market requirements. Preferably, the nitrogen content ranges from 2 to phosphorus from 2 to potassium from 2 to 10% and sulphur from 1 to 12%, by weight. Typically, a composition of the present invention may comprise brown coal 30%, nitrogen 10%, phosphorus 9% and potassium by weight.

In the fertilizer composition of this invention, brown coal or lignite acts as an effective binder, retainer, or diluent for the added fertilizer additives such that the release of the fertilizer additives is controlled. The use of brown coal or lignite produces an 910801jmsres.012,42932.res,6 k 7 effective controlled or slow release fertilizer. In addition, the use of brown coal or lignite combines the benefits of organic matter as a soil conditioner on one hand and fertilizer on the other into the one product.

Brown coal or lignite also contains large amounts of humic acids which are known to be highly beneficial to plant growth and soil binding ability.

In a preferred embodiment of the composition of the invention, the rate of fertilizer release may be altered .o as required by the addition of an acidic or alkaline material to digest the brown coal or lignite in order to change its binding properties. Suitable acids or alkalis include, for example, sulphuric acid or nitric acid and potassium hydroxide, sodium hydroxide, calcium hydroxide, i ammonium hydroxide or ammonia.

.4o4 1 In another aspect of this invention, there is t provided a process for the preparation of a compound fertilizer composition as broadly described above, which comprises the step of blending said brown coal or lignite with said organic or inorganic fertilizer additive(s), and optionally pelletizing or granulating the blended product. In a preferred embodiment of this process, the said brown coal or lignite is initially milled and screened, for example to -10mm (more preferably -imm) particle size, in a hammer mill in a bed moist state (usually between 3 j

I

I-

8 o a.

O0 *Z 0 o 00a 00 0 .0 0 o 0 O to 70%, and more preferably between 50 to 68%, by weight on a wet basis). Water in an amount of 0 to 15% by weight may be added if desired to produce a paste for mixing, or for control of moisture in the final product.

The milled material is then mixed with fertilizer additives according the required formulation and thoroughly blended for a period ranging from 3 minutes to minutes, depending on the ratio of brown coal or lignite to fertilizer additives. The fertilizer additives may be added separately in any order, or together. Alkali or acid may then be added to the mixture to adjust the binding, and hence the release rate, as required. By way of example, alkali may be added so as to alter the pH of the fertilizer product to a value ranging from 4.0 to The mixture is then thoroughly mixed for a further period ranging from 3 minutes to 30 minutes.

The final fertilizer product is then prepared by placing the mixture in a drum or disc granulator to produce granulated (generally spherical) pellets or prills, or put through an extruder to produce extruded (generally cylindrical) pellets. Both forms of fertilizer product have similar controlled release properties using the same coal-fertilizer additive formulation.

00*0 O 00 0 0 A, 44 0 0 0 4.

0410 400,1 The control of moisture in the coal and fertilizer additive mixture is less critical when the mixture is to be extruded than when the mixture is to be granulated.

I

-9- Essentially, the mixture can be successfully extruded at moisture levels ranging from 25% to 55 or 60% (wt basis), depending on the coal type. In granulation, the size of the granules can be controlled by adjusting the moisture level, and additional water may be added at this stage if necessary. Essentially, the mixture is successfully granulated at moisture levels ranging from 55 to larger granules are produced by increasing the moisture level above The extruded pellets or granulated pellets or prills are then dried, for example in a rotary drum or fluidized bed drier, to equilibrium moisture level (usually between 5 to 10% by weight depending on the ambient conditions) to produce the final controlled release fertilizer product. It has been found that drying conditions can be important to the retention of pellet strength and integrity. In particular, drying the pellets ri( slowly and at a temperature between 200C and 250 0

C,

Ii .preferably between 80°C and 1500C, is recommended for ensuring pellet strength. A flow chart of the overall process as described is given in Figure 1.

In summary, this invention relates to the use of brown coal or lignite as a binder, retainer, diluent or media for fertilizers containing nitrogen, phosphorus, potassium or sulphur, including trace elements, to produce a fertilizer product which incorporates the benefits of

I

10 organic matter and fertilizer. The fertilizer product has slow or controlled release properties which can be altered according to the amount of acid or alkali added to the mixture.

Further features of the compound fertilizer composition of this invention, and of the process for the preparation thereof are illustrated, by way of example only, in the following Examples.

S1 Example 1 o of -10mm. The coal is not necessarily dried as bed moist 0 4 *o I minutes. Water is alndded to at the mixin i necessa is used. Trace elements are added to the mixture as requiredof -10mm. Ther eafteroal is not necessarily dried as bed moist cobyal is veryght of suitabis addedle for the process. mixture In this Example, coal at 60% moisture (wet basis) is used.

oimmedi. Approximately 1.0 kilogram of coal is first mixed with 700 grams of superphosphate (-0.21 mm) for five 0,1 minutes and then 200 grams of urea (-1mm) for five Sminutes. Water is added to assist the mixing if necessary (but generally no water is needed if the 60% moisture coal is used. Trace elements are added to the mixture as required. Thereafter, 50 ml KOH solution containing 66% by weight of KOH, is added to the mixture and thoroughly mixed for a further 15 minutes. The mixture is then immediately put through an extruder and formed into pellets with a wet diameter of 2 mm, or transferred to a i A t 60 oiu (e b

I

i o1 0 O t* 000 a a a a 0*4 a r 9004I 11 granulator to produce fertilizer prills. Larger pellets up to 25 mm can also be produced. These larger pellets are suitable for use with plants or fruit trees by imbedding the pellets into the soil.

The effect of moisture content is more critical in the step of granulation to form granular fertilizer prills than in extrusion to form extruded pellets. The size of the fertilizer prills is controlled by moisture addition such that increasing the moisture level will increase the size of prills obtained in the granulator.

The fertilizer products are then allowed to dry under forced air drying conditions at ambient temperature.

The equilibrium moisture level of the fertilizer products is between 5 to 10% by weight depending on the ambient cor' tions. A typical product analysis is given in Table 2.

Example 2 The procedure for preparation of fertilizer is similar to Example 1 except that instead of 200 grams of urea, a mixture of 50/50 urea and ammonium nitrate is added. The use of 50/50 urea and ammonium nitrate allows the effective control of readily released N in the forms of nitrate-N and ammonium-N. This ensures that nitrogen is continuously released over a longer period of time.

The ratio of urea:ammonium nitrate is varied according to 00 a a 0 0 o 40e o a 4 0 0441 a aI i L l 1 1 1 i 1 4 12 the requirements for nitrogen. A typical analysis for this fertilizer is given in Table 2.

Example 3 The same process as described in Example 1 is used except that instead of using the 50 ml of KOH solution, a mixture of 170 grains of KCl and 100 grams of CaO is used.

The use of the mixture of KCl and CaO effectively reduces the cost of the fertilizer product without affecting the other properties. Urea, ammonium nitrate or a mixture of these nitrogen additives can be used according to the requirements for the various forms of nitrogen. A typical analysis for this fertilizer is given in Table 2.

Example 4 4 <The same process as described in Example 1 is used 44 1 to produce this fertilizer. However, in place of 1 superphosphate, acid-treated rock phosphate is used. A mixture of 200 grams rock phosphate is thoroughly S acidulated with 140 ml of sulphuric acid and allowed :Sbd: to stand for 1 hour before the brown coal is added. Other additives remained the same with the option for urea, ammonium nitrate or a mixture of these nitrogen additives.

A typical analysis of this fertilizer is given in Table 2. i k 1 1 h .'i -13- TABLE 2 TYPICAL FERTILIZER ANALYSIS Ex.l Ex.2 Ex.3 Ex.4 Total Phosphorus as P 5.7 3.5 3.4 5.6 Water Soluble Phosphorus as P 3.1 2.2 1.4 3.2 Citrate Soluble Phosphorus as P 1.4 1.2 2.5 1.4 Total Potassium, K 3.9 5.3 Total Nitrogen, N 4.1 3.7 Ammonium-N 2.8 2.6 0.6 Nitrate-N 0.2 0.2 0.1 Total Sulphate, SO 4 9.4 10.9 11.0 opH (10% slurry) 4.5 4.5 4.9 3.4 004Organic Matter ()30 30 30 4 04 4

Claims (18)

1. 2. A composition according to claim i, wherein said fertilizer additive(s) comprise or include superphosphate (mono, double or triple), calcium phosphate, bone or bone meal, or acid-treated rock phosphate, or mixtures thereof.
2. 3. A composition according to claim 1, wherein. said fertilizer additive(s) comprise or include urea, ammonium nitrate, or ammonium sulphate, or mixtures thereof.
3. 4. A composition according to claim 1, wherein said fertilizer additive(s) comprise or include potassium hydroxide, potassium chloride, potassium sulphate, potassium nitrate, or potassium oxide, or mixtures thereof.
4. 5. A composition according to claim i, wherein said eI fertilizer additive(s) comprise or include calcium hydroxide, calcium sulphate, calcium nitrate, or calcium carbonate, or mixtures thereof.
5. 6. A composition according to any one of claims 1 to wherein each said fertilizer additive comprises up to by weight of the composition. fased L lij X4 4!
6. 7. A composition according to any one of claims 1 to 6, further comprising trace elements selected from copper, zinc, manganese, iron, molybdenum and boron.
7. 8. A composition according to any one of claims 1 to 7, in pelletised or granulated form.
8. 9. A process for the preparation of a compound fertilizer composition according to claim 1, which comprises the step of blending said brown coal or lignite with said organic or inorganic fertilizer additive(s) followed by addition of an acidic or alkaline material to digest said brown coal or lignite in order to change the binding properties thereof.
9. 10. A process according to claim 9, wherein the blended product is subsequently pelletised or granulated, and then dried to equilibrium moisture level. .4
10. 11. A process according to claim 9 or claim 10, wherein said said brown coal or lignite is used on a bed moist state.
11. 12. A process according to claim 11, wherein said brown coal or lignite has a moisture content of between 40 and 70% by weight on a wet basis. a I
12. 13. A process according to any one of claim 10 to 12, wherein said blending step is carried out for a period of from 3 to 30 minutes.
13. 14. A process according to any one of claims 10 to 13, wherein acid or alkali is added to the blended product and further blended for a period of from 3 to 30 minutes. A process according to claim 9, wherein the blended product is extruded at a moisture level of from 25% to by weight. 92n' 2 ii: I ~as~r I ".I t .4 16
14. 16. A process according to claim 9, wherein the blended product is granulated at a moisture level of from 55 to by weight.
15. 17. A process according to any one of claims 9 to 16 wherein the blended product is dried at a temperature between 20 0 C and 250°C.
16. 18. A process according to claim 17, wherein the blended product is dried at a temperature between 80 0 C and 1500C.
17. 19. A compound fertilizer composition, when produced by the process of any one of claims 9 to 18.
18. 20. A slow or controlled release compound fertilizer composition, or a process for the preparation thereof, substantially as hereinbefore described with reference to the Examples and/or drawing. r t r re r r t II I: rr 9Il t I t I I ril Dated this 1st day of August, 1991 DAVIES COLLISON Patent Attorneys for COAL CORPORATION OF VICTORIA 1.1 lo oljrsrems.01Z4293.res, 16 i ,P