WO1991009820A1

WO1991009820A1 - Treatment of carbonaceous material

Info

Publication number: WO1991009820A1
Application number: PCT/AU1990/000602
Authority: WO
Inventors: Bruce Roy Thompson
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-12-22
Filing date: 1990-12-20
Publication date: 1991-07-11
Anticipated expiration: 1992-06-22

Abstract

A carbonaceous material such as lignite is subject to the action of a bioactive agent comprising Actinomycetes and other microbial flora and enzymes capable of degrading the carbonaceous material. The resulting modified carbonaceous material may be mixed with a binder comprised of cellulose fibres to produce a material suitable for use as a fertilizer and/or soil conditioner.

Description

TREATMENT OF CARBONACEOUS MATERIAL

TECHNICAL FIELD

This invention provides a novel method for the treatment of carbonaceous material to modify its structure. The resulting modified material finds particular, but not exclusive, application as a fertilizer and/or soil conditioner.

The extensive use of chemical fertilizers over the last 50 years has not been without associated problems. Apart from being an expensive procedure, chemically fertilized soils gradually suffer degradation and surface runoff and groundwater sources in the vicinity are contaminated by excess fertilizer application. It is generally agreed that the preferred method of farming involves the maintenance of the organic content of the soil by mulching or ploughing in crop wastes. This environmentally friendly method of land-use has the advantage of helping to maintain soil structure, ensuring a slow release of nutrients, and maintaining soil moisture levels; thus it also reduces water usage. However, this technique has a limited application because of the lack of quantities of suitable carbonaceous mulch.

Lignite in its natural form has some of the required attributes such as moisture holding ability, soil forming ability and it maintains a capacity to slow the release of nutrients. However, it is generally unsuitable for mulching alone because it lacks various trace elements and is too easily oxidised to a dust. Ground lignite also tends to reduce soil porosity, and it can also be a dangerous substance to transpor .

The present invention enables natural lignite to be treated so as to produce a modified material more amenable to use as a fertilizer and/or soil conditioner.

Although the invention has particular application to the treatment of lignite it may also be applied to other naturally occurring carbonaceous materials such as peat, subbituminous coal or sewage sludge. Moreover, although the resulting modified carbonaceous material may be used as a fertilizer or soil improver it may have other uses such as in the production of activated carbon. DISCLOSURE OF THE INVENTION

The invention broadly provides a method of modifying a carbonaceous material by subjecting that material to the action of a bioactive agent.

Preferably, the bioactive agent comprises bioactive micro-organisms and enzymes of a kind found in natural compost. More particularly, the bioactive agent may comprise Actinomycetes, streptomyces, bacillus sp, pseudomonas etc and enzymes capable of assisting in the degradation of the carbonaceous material and the release of stearic acids and nutrients.

The carbonaceous material may be lignite and the modified material may be produced for use as a fertilizer and/or soil conditioner.

The invention further provides a method of producing a fertilizer and/or soil conditioner comprising the steps of subjecting a carbonaceous material to the action of a bioactive agent and adding a binding medium to the resulting modified carbonaceous material.

The carbonaceous material may be lignite and the bioactive agent may comprise bioactive organisms and enzymes of a kind found in natural compost, such as Actinomyectes and enzymes. Some such agents are commercially available in various forms but specific cultures may be prepared for special applications.

The modified carbonaceous material and binding medium may be extruded, moulded, cast, rolled or otherwise formed into structurally coherent pieces or articles. It may, for example, be formed into pellets for large scale farming applications or formed into sheets, strips, troughs, dishes,pots, boxes or other shapes suitable for horticultural purposes.

Preferably, the binding medium is comprised of cellulosic fibres. It may, for example, be comprised of paper fibres.

The invention also extends to a modified carbonaceous material produced by subjecting a naturally occurring carbonaceous material to the action of a bioactive agent.

The invention further extends to a fertilizer and/or soil conditioner comprising a mixture of binding medium and a modified carbonaceous material resulting from the action of a bioactive agent on a naturally occurring carbonaceous material, for example lignite. BEST MODES OF CARRYING OUT THE INVENTION

In a typical process carried out in accordance with the present invention, lignite is ground to about minus 1/8" mesh and water added to form a slurry in a batch tank. This slurry is then treated with suitable reagents for example CaCo3 to increase its Ph. The slurry is then inoculated with bioactive microorganisms and enzymes commonly found in natural compost; (between <.001% and 0.01% by weight of the active ingredients will generally be required). The mixture is gently stirred for 8 hours. The bioactive agents may include microbial flora such as Actinomycetes or other selectively cultivated and adapted bacteria.

The pre-treatment of the lignite as described significantly alters its physical and chemical characteristics. It binds together more readily, re-wets more quickly, and more rapidly transforms into a true soil. The inherent problems of pore binding and the retention of moisture below a value 15% associated with untreated lignite are largely overcome.

At this stage other nutrients are added to make up the recognised deficiencies in lignite as a growing medium such as nitrogen, phosphorous and potassium bearing compounds. Various ratios of nitrogenous, phosphorous and potassium compounds may be required for different applications but if the material is to be used as a growing medium these constituents would comprise no more than 10% by weight. However, higher proportions could be incorporated if the material is to be used as a fertilizer only, in this case the fibre ratios would change. The high proportion of carbonaceous material to nutrients results in a product that releases the nutrients on demand, i.e. a slow release fertilizer. The nutrients remain bound to the carbonaceous material.

The resulting carbon-rich product could be dried and used as a fertilizer and soil improver at this stage but has been found to be rather friable. Thus, in the preferred process, pulped fibrous material such as waste paper in the form of a rather thick slurry or as a dry 'flock' is added to the treated lignite to bind it into a material that can be produced in a pelletized form suitable for large scale farming applications or moulded, cast or rolled into various shapes suitable for other horticultural applications. It has been found that as little as 10% by weight of paper fibre is sufficient as a binder but other proportions may be required for specific applications. Binders such as clay or zeolite can also be incorporated to enhance the product density and pellet strength but the use of cellulose fiber maintains the highest carbon content of the product.

The cellulose fibre binder can be produced by pulping waste paper with water or by a process of 'beating' to produce a paper 'flock'. If the product is to be pelletized, water usage should be kept to a minimum since the moisture content has to be reduced either by natural or forced drying to about 30% in the finished product but in other cases the product can be pumped or sprayed in a slurry form.

The resulting 'dough' can be pelletized, extruded in various forms or rolled flat. Increased pressure will increase the density of the final product and thus will vary the rapidity of its breakdown to soil elements on re-wetting, increasing the slow release characteristics of the final _^ product. Mechanical processes will speed the drying process to achieve a moisture content of between 20% and 35% again depending on the lignite type. INDUSTRIAL APPLICATION

The invention has particular application to the production of fertilizers and soil conditioners.

Since the product contains nearly 100% carbonaceous material of varying density and can be manufactured with a high porosity and with added nutrients, it is also suitable for other uses such as the basis for the production of a bioactive material designed to treat contaminated water and soils, the bacterial cultures incorporated being cultured for various environmental contaminants such as oils and phenols. For example, the material is naturally oeleophilic and can be made with a density so low that the material will float, and can be spread across an oil slick, where bacterial action can commence to break down the oil slick.

Claims

1. A method of modifying a carbonaceous material comprising subjecting the carbonaceous material to the action of a bioactive agent capable of degrading that material.

2. A method as claimed in claim 1, wherein the bioactive agent comprises bioactive micro-organisms and enzymes of a kind found in natural compost.

3. A method as claimed in claim 1, wherein the carbonaceous material is lignite and the bioactive agent comprises Actinomycetes and enzymes capable of degrading lignite.

4. A method of producing a carbonaceous material product, comprising the steps of subjecting a carbonaceous material to the action of a bioactive agent capable of degrading that material and adding a binding medium to the resulting modified carbonaceous material.

5. A method as claimed in claim 4, wherein the carbonaceous material is lignite and the bioactive agent comprises Actinomyectes and enzymes capable of degrading lignite.

6. A method as claimed in claim 4 or claim 5, wherein the binding medium is comprised of cellulosic fibres.

7. A method as claimed in claim 6, wherein the cellulosic fibres are paper fibres.

8. A method as claimed in any one of claims 4 to 7, wherein the modified carbonaceous material and binding medium is formed into pellets.

9. A fertilizer and/or soil conditioner comprising a mixture of a binding medium and a modified carbonaceous material resulting from the action of a bioactive agent on a naturally occuring carbonaceous material.

10. A fertilizer and/or soil conditioner comprising carbonaceous material resulting from the action of Actinomycetes and enzymes on lignite and a binding medium comprised of cellulosic fibres.