DE3404469A1 - Process for upgrading low-grade coal - Google Patents

Abstract

A process for upgrading low-grade coal is proposed, which comprises grinding the low-grade coal to a degree of fineness at which at least 40% pass through a screen having an open mesh width of 0.053 mm and is sufficient to destroy the cellular structure of the coal. Water is added to form a suspension of the coal. Fibrous materials and/or non-fibrous chemical binders are added to the coal suspension before or after it is formed. The suspension is sun-dried and lifted at a time when the coal has a moisture content corresponding to its plastic (or deformable) state. If necessary, the moisture content of the coal is occasionally increased in order to ensure a consistency favourable for the extrusion and/or forming of the coal and for the dimensional stability after extrusion and/or forming. The coal is then extruded and/or formed (unless this has already been done during lifting) and then dried in the sun or under controlled conditions.

Description

Process for refining low-quality coal

The invention relates to a method for refining low-grade coal, in particular a method in which sun drying of the refined product is used to make lumps or pieces of coal more uniform Generate size and shape for use in processes or handling systems for industrial and commercial furnaces and reactors are suitable, e.g. B. in the size and shape of lignite briquettes.

Australian patent 498,450 describes a process for refining low-grade coal, wherein the low-grade coal is ground to a degree of fineness of at least 40% through a sieve with a clear mesh size of 0.053 mm (300 mesh B.S.S.) and is sufficient, destroy the cellular structure of the coal, further using water to form a slurry of the ground charcoal is added, preferably during the grinding, which is then followed by resulting mixture is at least partially dried.

The end product has a low moisture content, higher heat content and improved physical strength.

A method of reducing moisture

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ORIGINAL INSPECTED

content of the slurry applies sun drying in exposed "fields".

Sun-dried coal is widely used in industrial and commercial furnaces and reactors, where the process or handling system is relatively uniform in terms of coal lumps Size and shape required.

Current production methods for producing sun-dried coal are based on the concept to "harvest" the product in a dry or semi-dry state. Unfortunately, however, a break the product obtained in this way into lumps of irregular size and shape. ,

In order to remedy these difficulties, the applicant wrote in the Australian provisional patent application No. PF6371 / 82 (unpublished and abandoned) proposed the sun-dried coal to harvest at a time when their moisture content is in the plastic (or malleable) state corresponds, the moisture content of this coal being adjusted to a value at which the consistency useful for extruding and / or shaping the char as well as for maintaining the shaped shape after extrusion and / or molding, whereupon the carbon is extruded and / or is shaped and dried under controlled conditions.

It has now been found that the aforementioned proposal has the disadvantage that, under certain circumstances, the resulting product may not be as described above in US Pat mentioned application is satisfied, d. H. the sun-dried coal does not always die

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retains original size and shape; in other words there may be physical deterioration during of the drying process described subsequently occur on the extrusion and / or shaping of the coal. 5

It is therefore a primary concern of the invention to avoid the stated difficulty and uncertainty which is associated with the method described in the cited patent application, and an improved one Specify a process for the production of sun-dried coal, in which the resulting product is obtained in pieces or lumps of uniform size and shape suitable for the Use in processes or handling systems of industrial and commercial furnaces and reactors are e.g. B. in the size and shape of brown coal briquettes.

To solve this problem it is provided according to the invention that the low-grade coal on a Fineness is milled, which is at least 40% through a sieve with a mesh size of 0.053 mm can pass and is sufficient to destroy the cellular structure of the coal that water to form a Slurry is added to the coal, preferably before grinding, that additives in fibrous form Materials and / or non-fibrous chemical binders before or after forming the slurry added that the slurry is sun-dried that the sun-dried Coal is harvested at a time when the coal has a moisture content corresponding to that plastic or deformable state that, if necessary, temporarily the moisture content of the Coal is increased to one for extrusion

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and / or shaping and maintaining the shaped shape to ensure the required consistency of the coal, and that the coal is extruded and / or shaped, if this is not done during harvesting, and thereafter dried in the sun or under controlled conditions.

The term "extruding and / or shaping" is intended to mean any type of shaping process include. This shaping can advantageously be carried out during the "harvesting process".

The non-fibrous additive is advantageous during the wet milling of the coal to form the aqueous slurry is added while the fibrous Advantageously as an additive, but not necessarily added to the slurry after the grinding process has been completed will.

The additive is normally used in an amount up to 10% (dry weight of the additive based on the weight of dry coal) was added.

The fibrous material can be of vegetable origin, e.g. B. from bagasse, cotton, paper pulp, Wood, straw or suitable recycled waste material.

Alternatively, the fibrous material may be a synthetic polymer based material.

The non-fibrous chemical binder is advantageous a commercially available lignin chemical product or black waste liquid used in the process for the production of paper pulp or the like.

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As mentioned above, a combination of fibrous and non-fibrous material can be advantageous chemical binders to use.

While further drying from the plastic state of the coal leads to its overall shrinkage, every single piece or lump retains its discrete shape free of breaks within each piece. 10

The invention will now be based on preferred exemplary embodiments shown in FIGS. 1 and 2, explained in more detail.

Embodiment 1

Referring to Fig. 1, raw lignite is poured into a with the addition of water and fibrous material Fine mill introduced and mixed therein so that the raw lignite is ground to a degree of fineness which is at least 40% through a sieve with a mesh size of 0.053 mm (300 mesh B.S.S.) lets through and is sufficient to destroy the cellular structure of the coal.

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The resulting carbon / fiber slurry has approximately the following composition: 78-79% water, 1-2% fiber material, 20% carbon. This slurry then undergoes sun drying in one or more Beds subjected to whereupon the coal is harvested at a time when its moisture content corresponds to a plastic (or deformable) state. The resulting charcoal can either be molded and / or extruded or shaped during harvesting. The molded

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Coal can then be further sun-dried under controlled conditions and has approximately the following composition: 15% water, 4-8% fiber material, 77-81% coal.
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Embodiment 2

According to FIG. 2, raw lignite and water are placed in a fine mill, where the coal is reduced to a degree of fineness is ground, which is at least 40% through a sieve with a mesh size of 0.053 mm (300 mesh B.S.S.) and is sufficient to destroy the cellular structure of the charcoal. the the resulting slurry is then poured into a mixing

mill given. _{i ::}

Crude fiber is placed in a dispersion mill and dispersed with the water, so that a fibrous Pulp is created. This fibrous pulp is then placed in the mixer mill with the coal slurry, to create a carbon / fiber slurry of about the following composition: 78-79% water, 1-2% fiber material, 20% carbon.

The process is then continued in the same way as explained with reference to Example 1. It results in a coal of the same composition as in Example 1.

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Claims (9)

340U69 Dr.-Ing. Roland LiesegSng Patent attorney European patent attorney Sckellstrasse 1 D-8000 Munich 80 Telephone (089) 4 48 24 Telex 5214 382 pnli d Tolnkopicror (0B9) 7770480, 772U4B1 Tolngramme pnternus munchun Post check Munich 39418-80? Hypobank Munich 6400 194 333 AUSTRALIAN PORTLAND CEMENT LIMITED Reuses Munich ₂₆ o3oo7 South Melbourne, Australia
P 128 05 Process for refining low-quality coal Claims, '.: ^ experience for refining low-quality coal, ■ 'characterized in that the Low-grade coal is ground to a degree of fineness of at least 40% through a sieve of a clear mesh size of 0.053 mm (300 mesh B.S.S.) can pass and is sufficient for the cellular To destroy structure of coal, water is added to form a slurry of coal is, preferably before grinding, that additives in the form of fibrous materials and / or non-fibrous materials chemical binders can be added before or after forming the slurry that the The sun-dried slurry is that sun-dried charcoal at a time is harvested when the coal has a moisture content corresponding to the plastic or deformable Condition has that, if necessary, temporarily increases the moisture content of the coal is made to a required for extruding and / or molding and maintaining the molded shape 340A469 Ensure the consistency of the charcoal and that the charcoal is extruded and / or molded, if provided this does not happen during harvest, and then in the sun or under controlled conditions is dried. 2. The method according to claim 1, characterized in that the non-fibrous Additive added during the wet milling of the coal to form the aqueous slurry will. 3. The method according to claim 1, characterized in that the fibrous Additive is added to the slurry after wet milling. 4. The method according to any one of claims 1 to 3, characterized in that the additive added up to an amount of 10% (dry weight of the additive based on dry coal) will. 5. The method according to any one of claims 1 to 4, characterized in that the fibrous Material is of vegetable origin. 6. The method according to claim 5, characterized in that the fibrous Material from the group of bagasse (squeezed sugar cane stalks), cotton, paper pulp, wood, Straw and reclaimed waste material is selected. 7. The method according to any one of claims 1 to 4, characterized in that the fibrous COPY 340U69 Material a material based on a synthetic Polymers is. 8. The method according to any one of claims 1 to 4, there- characterized in that the non-fibrous chemical binder is a commercially available lignin or black waste liquid obtained in the manufacture of paper pulp or the like.
10 9. The method according to any one of claims 1 to 4, characterized in that the additive is a combination of fibrous material and non-fibrous chemical binders. COPY i