Chemistry: fertilizers – Processes and products – Organic material-containing
Reexamination Certificate
2001-11-01
2004-01-27
Sayala, Chhaya (Department: 1761)
Chemistry: fertilizers
Processes and products
Organic material-containing
C071S014000, C071S025000
Reexamination Certificate
active
06682577
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a soil modifier produced from a solid fuel, or from a so-called refuse-derived fuel (RDF), obtained by molding refuse after crushing and drying.
2. Description of the Related Art
Various technologies for refuse disposal and recycling have been developed in recent years, whereby flammable refuse is picked up from wastes and recovered followed by crushing, drying and molding to form a solid fuel. Such technologies are disclosed, for example, in Japanese Patent Nos. 2,865,541 and 2,981,399, and Japanese Unexamined Patent Application Publication No. 8-86569.
In these technologies, urban trash, domestic garbage, industrial waste and other refuses are crushed and dried for reducing the moisture content, followed by a selection process for removing glasses and ceramics. Then, the processed refuse is molded into a prescribed shape, for example a crayon shape, to reuse as the solid fuel. Such solid fuel from refuse is called RDF.
While solid fuel from refuse has been utilized as heat sources for air conditioning of various facilities or for power plant fuels, additional investments for installation of new equipment suitable for refuse-derived fuel, or for repair of existing equipment are required for utilizing the solid fuel. Since the amount of refuse generated is increasing day by day, it is desirable from the view point of environmental protection to increase production of the refuse-derived fuel.
However, it is meaningless to merely increase the production of refuse-derived fuel under the current situation where installation of facilities for practically utilizing refuse-derived fuel is insufficient.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to facilitate consumption of refuse-derived fuel by exploring new fields for practically utilizing the refuse-derived fuel. Specifically, the present invention proposes methods for utilizing solid refuse from the view point of environmental protection.
The inventors of the present invention have investigated the method for utilizing refuse-derived fuel so as to be useful for improving the environment, and have had an idea to use it as soil modifiers. The inventors have intensively studied another method for allowing refuse-derived fuel created by environmentally protective refuse disposal process to contribute to modification of the soil, and found that porous materials obtained by dry distillation of the refuse-derived fuel is suitable as the soil modifier. The present invention is able to largely contribute for carrying out safe and ideal recycling for returning resources into the nature.
The present invention provides a soil modifier comprising porous materials obtained by dry distillation of refuse-derived fuel.
The porous material constituting the soil modifier preferably contains carbon, nitrogen, sulfur, phosphorus, potassium and zinc. More preferably, the carbon content is 30 to 70 mass %. The porous material in one of the preferable embodiments contains 10 mass % or less of nitrogen, 1 mass % or less of sulfur, 10 mass % or less of phosphorus, 10 mass % or less of potassium and 1 mass % or less of zinc. The porous material satisfying both compositions, or comprising 30 to 70 mass % of carbon, 10 mass % or less of nitrogen, 1 mass % or less of sulfur, 10 mass % or less of phosphorus, 10 mass % or less of potassium and 1 mass % or less of zinc, is particularly preferable.
Any of the soil modifiers above preferably comprise 50% or more of the porous materials having a particle diameter of 0.5 to 5.0 mm.
Any of the soil modifiers above preferably comprise the porous materials having a specific surface area of 25 to 500 m
2
/g.
The porous material is preferably washed with water in any of the soil modifiers described above.
Any of the soil modifiers described above comprise the porous materials having a particle diameter of 0.1 to 50.0 mm.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described hereinafter in detail.
The soil modifier according to the present invention is produced from a solid fuel processed into a prescribed shape after crushing, drying and molding of refuse, or a so-called RDF, as a starting material. The present invention utilizes a porous material obtained by dry distillation of refuse-derived fuel as a soil modifier. Accordingly, the soil modifier according to the present invention contains nitrogen, sulfur, phosphorus, potassium and zinc as well as carbon originating from refuse.
A porous powder is obtained by dry distillation of refuse-derived fuel comprising common refuse such as urban trash, domestic garbage and office trash, as well as plant and animal residues and industrial wastes such as refuse plastics, paper, woods and fabrics, and sludge and refuse oils or other wastes comprising a mixture thereof. The inventors of the present invention found that physical properties of a soil such as moisture retention, fertilizer retention and water permeation are improved by mixing the porous material in the soil. It was also noticed from the studies of dry distillation conditions of the RDF and compositions of the porous material that RDF is most suitable for the soil modifier because the porous material contains three elements of the fertilizer of nitrogen, phosphorus and potassium, as well as calcium and zinc that serve as nutritious elements for the plants, as shown in Table 1. More advantageously, the soil is activated and improved to be suitable for growth of the plant by spreading the porous material as a result of proliferation of bacteria in the fine pores of the porous materials. Consequently, the inventors of the present invention have started the development for applying the porous material obtained by dry distillation of refuse-derived fuel to the soil modifier, and finally attained the present invention.
Typical examples of the soil modifier include use of charcoals and compost derived from common refuse. However, the charcoal is disadvantageous for use as the soil modifier since forest resources may be depleted by consuming trees, in addition to very high cost for using a large quantity of the charcoal as the soil modifier because production of the charcoal is expensive and it is required to be granulated before use. The compost of the refuse also involves, on the other hand, many problems that it is liable to give out bad smell, and it requires a long period of time for fermentation with anxieties of resumption of fermentation thereafter to make it difficult to handle the compost of the refuse.
The production cost of the soil modifier taking advantage of the porous material obtained by dry distillation of refuse-derived fuel is, on the contrary, very cheap since various wastes may be used as starting materials. A powder or granules mainly comprising carbon are obtained by removing volatile components by dry distillation, and carbon substances obtained therefrom are converted into porous materials during dry distillation. Accordingly, the product is most suitable for the soil modifier that can be easily handled.
The porous material to be used for the soil modifier in the present invention preferably contains 30 to 70 mass % of carbon. In other words, the porous material obtained by dry distillation has a sufficient specific surface area when the carbon content is 30 mass % or more. Bacteria can advantageously proliferate in the pores that sufficiently manifest a moisture retaining effect or, on the contrary, water permeating effect. Retention of fertilizer components is also excellent when the porous material is used by mixing with the fertilizer. The specific surface area is prevented from decreasing due to insufficient dry distillation by allowing refuse-derived fuel to contain 70 mass % or less, preferably 60 mass % or less, of carbon.
The porous material containing an appropriate amount of carbon may manifest an effect as the soil modifier by functioning as an adsorbent for moisture and fertilizer components and as a buffer material in the soil as hitherto
Nagata Ryoichi
Tsubota Takuya
Yamaguchi Yasuyuki
Yamauchi Yutaka
JFE Steel Corporation
Sayala Chhaya
Young & Thompson
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