BACKGROUND TO THE INVENTION

THIS invention relates to a method for producing an agricultural composition and to an improved agricultural composition.

South African patent no. 2001/6028 teaches a method and apparatus for producing humic substances, particularly fulvic and humic acid. The method includes the steps of introducing a raw material in the form of a fossil fuel or composted organic material into a closed reactor vessel, and introducing an acidic or basic oxidizing agent to the reactor vessel to cause an exothermic chemical reaction.

It is an object of this invention to provide an improved method for producing an agricultural composition, and an improved agricultural composition.

SUMMARY OF THE INVENTION

A first aspect of the invention relates to a method for producing a composition, particularly an agricultural composition, the method including the steps of:

1) introducing a raw material in the form of fossil fuel, a composted organic material or a mixture of a fossil fuel and composted organic material into a reactor vessel;

2) introducing an acidic oxidising agent to the reactor vessel to cause an exothermic chemical reaction which forms a reaction product; and

3) combining the reaction product with an acetic acid solution such as pyroligneous acid so that the acetic acid solutions solubilizes fulvic acid into the solution, to provide a supernatant liquid containing fulvic acid and an acetic acid such as pyroligneous acid that may be used as a liquid agricultural composition.

Preferably, the raw material is a fossil fuel such as coal that has a high vitrinite analysis and low ash content. By high vitrinite analysis is meant 80 -90%. The coal should be ground to a median particle size of 50 to 100 microns.

The reactor vessel is preferably closed, and the pressure within the reactor vessel above 1 bar to 3 bar, typically between 1 bar and 2 bar.

The oxidizing agent in step 2) is preferably nitric acid. The ratio, by means of nitric acid to raw material, is preferably from 0,5 : 1 to 1 : 1 ,5, usually about 1 : 1.

The pyroligneous acid may have a concentration of from 10% to 20%, typically 12%.

Preferably, the supernatant liquid has a pH of from 2 to 4, typically about 2.5.

The liquid agricultural composition may contain 5% to 15%, typically 10% to 12% fulvic acid and 5% to 20%, typically 10% to 15% acetic acid.

Insoluble material from step 3 may be used to make a humic acid agricultural composition containing humic acid and pyroligneous acid.

A second aspect of the invention relates to composition, particularly an agricultural composition, containing fulvic acid and an acetic acid such as pyroligneous acid.

The composition may contain 5% to 15%, typically 10% to 12% fulvic acid and 5% to 20%, typically 10% to 15% acetic acid.

BRIEF DESCRIPTION OF THE DRAWING

The drawing is a schematic representation of an apparatus which is used to produce a composition, particularly an agricultural composition, according to the method of the invention.

DESCRIPTION OF EMBODIMENTS

Referring to the drawing, an apparatus for producing a composition includes a reactor indicated generally by the numeral 10 and a scrubber system indicated generally by the numeral 13.

The reactor 10 includes a closed stainless steel reactor vessel 12. By "closed" is meant that fumes and gases from reactions in the reactor vessel are not liberated directly into the environment. The reactor vessel 12 has a bottom portion \4 and a top portion 16. The bottom portion 14 is in the form of an

inverted cone and slopes at an angle of approximately 45° to an inlet 18 at the base thereof. An inlet pipe 20 with a valve 22 is provided for pumping reactants into the vessel 12 via the inlet 18. The top 16 of the vessel 12 has a first top opening 24 which leads into first a conduit in the form of a first extractor pipe 26 which, in turn, leads to the scrubber system 13. The top 16 of the vessel is also provided with a lid 28 which can be opened to introduce reactants into the vessel 12. A mixer in the form of an auger 30, which is driven by a motor 31 , is provided for mixing reactants 32 in the vessel 12. The auger 30 is surrounded by a sleeve 33. In use, the auger 30 transports reactant up the sleeve 33 and out through a top opening 33a of the sleeve 33, to ensure good mixing of the reactants 32. The reactor vessel 12 is also provided with a thermometer 34.

The scrubber system 13 includes a neutralising vessel 35 into which the extractor pipe 26 from the reactor 12 extends. The neutralising vessel 35 contains a neutralising liquid 36 and the end 38 of the first extractor pipe 26 is submerged in the liquid 36. A second conduit in the form of a second extractor pipe 40 extends from the neutralising vessel 35 into a scrubber tower 42. Extraction means in the form of an extraction fan 44 is provided on the second pipe 40 for extracting fumes and gases from the reactor vessel 12, via the first extractor pipe 26 into neutralising vessel 35, through the neutralising liquid 36 and then into the scrubber tower 42 via the second extractor pipe 40. The lid 28 should be kept open when the extractor fan 44 is on to stop a vacuum from forming in the reactor vessel 12. The scrubber tower 42 is equipped with four nozzles 46 which are fed with pressurised water from a pump 48 to provide mist sprays 50. Water from the scrubber tower 42 is collected in a sump 52 at the base thereof and recycled to pump 48. A filter 53 made from steel or fibreglass wool is provided at the top of the scrubber tower 42.

A fossil fuel such as coal is ground finely (median particle size of 50 to 100 microns) and is high in vitrinite analysis and low ash content. By high in

vitriπite analysis is meant 80 - 90%. A suitable coal is Waterberg coal which is mined at the Grootegeluk Coal Mine in Ellisras, South Africa. Lignite or clay rich in organic matter would also be suitable for this method.

The composted organic material may be from animal origin, such as a manure (chicken, cattle or pig manure), or sewage sludge. The composted organic material may also be from plant origin, such as sugar cane pulp, seaweed, peatmoss or any other plant material. Advantageously, the organic material is treated with CMS (condensed molasses soluble) or molasses prior to the composting process.

One ton of finely ground coal or a composted organic material, or a combination of the two, is placed via the lid 28 into the reactor vessel 12. These materials are dry. The auger 30 is started and 300 litres of sulphuric acid is added to digest the organic matter. An air pipe is then attached to the valve 22 and air is pumped into the reactor vessel 12 via the inlet 18. At the same time, the auger 30 mixes the reactants within the reactor vessel 12. A pipe connected to a supply vessel containing nitric acid (60%) is then connected to the valve 22 and nitric acid is pumped into the reactor vessel 12 via the inlet 18. This causes an exothermic reaction within the reactor vessel 12. The temperature of the reaction is measured by the thermometer 34. The rate at which the nitric acid is pumped into the reactor vessel 12 is controlled to keep the temperature of the reaction below 18O ⁰ C. Typically, the temperature of the reaction is kept between 7O ⁰ C and 11O ⁰ C. When sulphuric acid, as described above is added, 1000 litres of nitric acid (60%) is added. If no sulphuric acid is added then 1200 litres nitric acid (60%) is added. The ratio, by means of nitric acid to raw material is from 0,5 : 1 to 1 : 1 ,5, usually about 1 : 1. The reaction continues for six to eight hours with the auger 30 mixing the reactants and with the sloped base 14 of the reactor vessel 12 causing a continual mix of reactants. This mixing process ensures that as much organic material as possible comes into contact with the nitric acid and complete

oxidation takes place. The pH of the reaction medium will be from 1 ,5 to 3. The pressure within the reactor vessel above 1 bar to 3 bar, typically between 1 bar and 2 bar.

During the reaction, fumes and gases from the reaction are extracted out of the exit 24 through the extractor pipe 26 and introduced into the neutralising vessel 35. In this case, the neutralising liquid 36 in the neutralising vessel 35 is 10% ammonium hydroxide which removes carbonaceous and NO _x substances from the fumes and gases. Thereafter, the fumes and gases pass via the second extractor pipe 40 into the scrubber tower 42 where they come into contact with the water mists 50. The mists 50 remove free ammonia from the fumes and gases so that purified gases exit from the scrubber tower 42.

Water collecting in the sump 52 contains organic and ammonium nitrate compounds substances which may be used in nutrient mixes for plants.

According to an embodiment of the present invention, when the reaction in the reactor vessel 12 has come to an end, five thousand litres of 10% to 20%, typically 12% pyroligneous acid is added to the reaction product in the reactor vessel 12 and the slurry so formed is mixed. The pyroligneous acid impregnates the reaction product and solubilizes fulvic acid into the solution. The resulting solution will have a low pH of about 2.5 and contains fulvic acid and pyroligneous acid. Insoluble substances are then allowed to settle to the bottom of the reactor and the supernatant liquid is pumped off. A cyclon filter may be used for this process. Approximately 4000 litres of liquid agricultural composition is obtained which contains 5% to 15%, typically 10% to 12% fulvic acid and 5% to 20%, typically 10% to 15% pyroligneous acid.

The pyroligneous acid (an impure acetic acid which is a byproduct from the manufacture of charcoal) extracts fulvic acid from the oxidized organic matter and provides an agricultural composition containing fulvic acid and

pyroligneous acid. When used in an agricultural composition, the fulvic acid and pyroligneous acid are both capable of being taken up by plants systemically and have a synergistic effect on both the growth of plants and the protection of plants against pests. Not only does the agricultural composition have better soil conditioning properties than compositions containing fulvic acid only or pyroligneous acid only, but the agricultural composition of the invention also benefits microbes and controls pests such as insects, for example ants, as well as mildew and fungus. When used as a foliar spray, the formulation stimulates growth, and flower and fruit indication. The pyroligneous acid also acts as a chelating agent for cations and improves uptake and mobility of nutrients in plants.

The combination of pyroligneous acid, fulvic and humic acid may also have added to it dextrose, plant nutrients and other active ingredients. For example, the pyroligneous acid may be included in agricultural compositions such as those described in South African patent no. 2001/6027, the content of which is incorporated herein by reference.

In accordance with a further embodiment of the invention, after the supernatant liquid has been pumped off the reaction product, the remaining solids at the bottom of the reactor 12 may be used to produce humic acid. The remaining solids are treated with a base such as ammonia gas, ammonium hydroxide or potassium hydroxide (which is pumped into the reaction vessel 12 via the inlet 18). An exothermic reaction takes place and the pH of the reaction medium rises to between 8 to 12, to form humic acid reaction product. This reaction does not generate large amounts of fumes and gases and it is usually not necessary to use the scrubber system 13. The humic acid reaction product will contain pyroligneous acid and may be dried and milled to form a powder that can be used in the bulk blending of dry fertilizers or incorporated into the granulation process of granular fertilizers. Alternatively, the dry material may be packed into filter bags which may be introduced to water and the humic and

pyroligneous acids will dissolve in the water which will have a high pH. Instead of drying the humic acid reaction product, water may be added to provide a slurry having a pH of 8 to 12 and the humic and pyroligneous acids dissolve in the water. Thereafter insoluble substances are allowed to settle and a supernatant liquid is pumped off using a cyclone filter. The supernatant liquid has a humic acid content of 10 to 40%, typically 30% and a pyroligneous acid content of 1 - 10%.

Examples of agricultural compositions of the invention will now be provided:

54 kg of urea was mixed with 10 to 25 It of a fulvic acid/pyroligneous acid composition produced by the method described above in water to make to 100 It of product. This resulted in a slow release fertilizer being produced which can be applied to a locus at a rate of 50 to 250 It per hectare. The transition of urea to ammonia and the release of nitrate is slowed thereby slowing the release of nitrogen to the locus. The leaching of nitrogen is also slowed.

20 kg of phosphorus acid was mixed with 20 kg of potassium carbonate. To this mixture was added 50 It of the fulvic acid/pyroligneous acid composition produced by the method described above in water to make up to 100 It product. This product can be applied as a foliar spray at a rate of 0,5 % to 1 % on crops such as tomatoes, peppers, potatoes, strawberries, citrus and avocado pears. Control of fungus diseases such as phytophtera, pitheam, rizechtonia, botritus and altenaria is possible. This product can also be used to control soil borne fungus diseases at a rate of 10 to 25 It per hectare.

Further specific agricultural compositions of the invention are set out below. In these examples the "fulvic acid PLA" is a fulvic acid/pyroligneous acid composition produced by the method described above, having a typical composition of 10 - 12% fulvic acid and 10 - 15% pyroligneous acid and a pH of 2 - 2.5.

FOLlAR APPLICATIONS

42.8 It MgNO3

14.03 kg KCO3

(KCO3 and HNO3 react with each other to form

16.48 It HNO3 KNO3)

25 It Fulvic PLA

2.5 kg Dextrose

7.2 lt H20

100 liter

Apply on various crops as a Foliar Spray at a rate of 1 - 2 % in water.

Total volume of mix 100 It per hectare - 1000 It per hectare depending on type of crop and size.

2 14.3 kg KCO3

17.14 It H3PO4 (Deflorinated) - (KCO3 and H3P04 react with each other)

25 LT Fulvic PLA

2.5 kg Dextrose

50 It H2O

100 It

Foliar Spray at a rate of 1 - 2 % or 2 - 5 It per hectare in 100 - 500 It of water per hectare.

SOIL APPLICATIONS

8.77 kg KCO3

28.57 It H3PO4

37 It NH4NO3

10 It Fuivic PLA

20 K H2O

100 It

Apply to soil at 50 - 250 It per hectare depending on crop need or soil requirement.

2 45 It CaNO3

45 It NH4NO3 10 It Fulvic PLA

100 It

Soil application of 50 - 1500 It per hectare divided into 4 - 6 applications during growing period.