JPS58104998A - Quality improvement of coal - Google Patents

Abstract

PURPOSE:To carry out simultaneously the dehydrating, deashing and spontaneous ignition-preventing treatments of a low-grade coal, by obtaining a tar through the dry distillation of part of a pulverized coal, performing the non-evaporation heating and dehydrating treatment of the rest, and then accomplishing a granulation in water of the above tar as a binder together with the resultant coal. CONSTITUTION:A low-grade coal such as brown coal, lignite, sub-bituminous coal, etc., is pulverized; part of the resulting coal being subjected to a dry distillation to distill water and a tar. From the rest (of the coal), the water contained is reduced through a non-evaporation heating. Subsequently, the resultant two kinds of coal is mixed with water into an aqueous solurry while incorporating the above tar as a binder, followed by carrying out a granulation in water.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for improving the quality of low-quality coal such as lignite, lignite, and sub-bituminous coal. This article relates to a method for reforming coal to be produced.

Coal is generally used for various purposes as fuel and in the chemical industry, and most of them are high-grade coal such as bituminous coal. On the other hand, although low-quality lignite, for example, accounts for about a quarter of the coals on earth,
At present, it is not widely used because dry lignite has a moisture content of up to 70%, and dry lignite is highly reactive and tends to spontaneously ignite. That is, in order to widely utilize these low-quality coals for fuel and chemical industry purposes, it is necessary to perform appropriate treatments such as dehydration and deashing, and reform them into coals that are easy to transport and store.

However, since Fi and bituminous coal are currently being used first, appropriate reforming technology for effective use of low-quality coal has not received attention, and therefore is currently an unfinished technology.

An object of the present invention is to propose a coal reforming method that facilitates the transportation and storage of low-quality coal and allows it to be easily used as fuel and in the chemical industry.

As a result of intensive research to achieve the above object, the present inventors have found that they finely pulverize coal, carbonize a portion of it to obtain tar, and dehydrate the remaining coal by non-evaporative heating. We have discovered that by adding tar as a binder to a water slurry of dehydrated coal and carbonized coal and granulating it underwater, coal can be dehydrated, deashed, and spontaneously ignited at the same time.

Coal in the present invention refers to lignite immediately after being extracted from a coal mine,
Refers to brown coal, sub-bituminous coal, etc. that has not undergone any treatment. For example, carbon content (C%) in the case of raw lignite
is less than 78%, and the calorific value is 7300 K on an anhydrous basis.
Cat/~ or less. That is, the method of the present invention consists of the following four steps.

The first step is to pulverize the coal.

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Next, in the second step, a portion of the coal pulverized in the first step is carbonized to distill off water and tar, and the remaining coal is dehydrated by non-evaporative heating. The amount of raw coal to be carbonized is desirably determined so that the amount of tar obtained by carbonization corresponds to 2% or more of the coal component in the total amount of coal. If this is not the case, the aggregation in the fourth step described below may not be performed efficiently, and there is a possibility that the recovery rate of coal will decrease. For example, the carbonization temperature of raw lignite is preferably 200C to 600C%, particularly preferably 350C to 5%.
It is 00C. In this case, carbonization at a low temperature yields an insufficient amount of distillate, and carbonization at a relatively high temperature results in thermal decomposition of the distilled tar. Furthermore, it is preferable that the non-evaporative heating dehydration temperature of raw lignite is 200C to 350C. Originally, low-rank coal often exhibits hydrophilic properties because it chemically binds oxygen elements, and this is one of the reasons why it contains a large amount of water. Oxygen-containing bonding groups are destroyed by decarboxylation reactions at temperatures above 200C, but at temperatures above 350C, the coal itself is thermally decomposed.

This is because For example, the present inventor has experimentally found that almost all raw lignite can be modified to have a water content of 20% or less by this non-evaporative heating and dehydration treatment.

In the third step, the coal after carbonization and the coal after non-evaporative heating are mixed as an aqueous slurry, and the tar distilled in the step @2 is added to the aqueous slurry as a binder to coagulate coal particles. It is something that makes you As for the water used in the aqueous slurry, it is of course possible to use the water distilled out along with the tar in the second step and the water obtained by the non-evaporative heating dehydration treatment. At this time, a surfactant may be used to reduce the amount of tar and the stirring power for coagulation. A favorable fact in this step is that when the coal fine particles are agglomerated, the ash fine particles do not agglomerate because they are hydrophilic, and the agglomerated particles have been subjected to a deashing treatment. Tar obtained from coal is designated as Special Publication No. 11155.
As stated in Publication No. 6-15379, it has a certain kind of molecular group that is lyophilic to ash fine particles as well as to carbonaceous particles, so it is generally difficult to separate ash particles to a high degree. It is often thought that it cannot be achieved. However, the present inventor has found that this concept applies only to bituminous coal with an ash content of 20% or more.For example, in the case of lignite, the ash content is often low by nature, and the ash content is several percent. In many cases, the ash content is as follows.According to the findings of the present inventors, even in the case of lignite with an ash content of several percent or less, the deashing effect in the third step still works, and the coagulation Ash separation of brown coal: 1% or less to 3%
It will be about.

The fourth step is to separate the aggregates from the water. The agglomerates in this step generally have a diameter of α3 to 5α and can be easily separated from water using suitable means such as vibrating sieves or centrifuges to further increase the dewatering effect.

What is important here is that by coagulating in water coal whose moisture content has been dehydrated to about 10% to 20% by non-evaporative heating dehydration treatment and coal whose moisture content has been reduced to zero by carbonization. This is because the moisture content of the coal after the completion of the process can be made to range from several percent to several ten percent. Furthermore, the reduction in oxygen atom content due to heat treatment of coal also has the effect of increasing the calorific value per unit weight during combustion.

Next, the present invention will be explained by examples.

Embodiments of the present invention will be described with reference to the drawings.

Raw lignite 1 is fed to crusher @ 2 and crushed into 200 meshes (7
Particles with a particle size of 4μ) or less are pulverized to 80% or more.

91 parts of the finely pulverized raw brown coal 3 is introduced into a carbonization device 4, and the remaining raw brown coal 5 is introduced into a non-evaporation heater 6. However, in this case, if the entire amount is carbonized, the non-evaporative heater 6 system is omitted. The raw brown coal 3 is carbonized in the carbonization device 4, and the distilled water, gas, and tar 7 are led to the separator 8. The separator 8 separates the gas into gas 9, water 10, and tar 11. On the other hand, the lignite 12 treated in the non-evaporative heater 6 is led to a stirring tank 13. 9. The fine brown coal 14 after carbonization is similarly introduced into the stirring tank i'3, and □ water 15 is added and mixed to form an aqueous slurry. Soshi bi.

Then, tar 11 is introduced from the separator 8, and lignite particles are agglomerated using the tar 11 as a binder. At this time, if necessary, a surfactant is added to help separate the charcoal and ash.

The agglomerated lignite 16 is led to a separator 17, such as a vibrating screen, to separate it from water and ash particles. The separated millet particles 18 are then led to a centrifuge 19 for further dehydration treatment. In addition, separated water and ash content 20
is discharged, and the water 21 dehydrated by the centrifuge 19 is also discharged. Modified lignite 22 having the effects of dehydration, deashing, and prevention of spontaneous combustion is obtained as a product.

Examples (Example 1) I kg of raw lignite having a moisture content of 30.2% and an ash content (dry basis) of 11.7% was pulverized in a ball mill to give a particle ratio of 200 mesh or less to 82%. Of these, 0.3 and 4 were carbonized at 500C for 2 hours to obtain 29g of tar, while
0.7 kg of the remaining raw lignite was subjected to 1 atmosphere of non-A pressurized de-beaming at 400c for 2 hours. These places 1.

The lignite was made into a 35% water slurry, and the lignite particles were agglomerated using nine tar obtained by carbonization as a binder.

The total amount of aggregated particles after centrifugation was 0.62 KF. The moisture content of this flocculated brown coal is 13.1%, and the ash content is 6.
．． 1% and high quality.

<Example 2> Using raw lignite with a moisture content of 60% and an ash content (dry basis) of L2%, modification was carried out in the same manner as in Example 1. As a result, the moisture content was 18% and the ash content was 1. It was of high quality at 7%, and the recovery rate of coal components was about 90%.

<Example 3> Raw lignite I with a moisture content of 60% and an ash content (dry basis) of 6.5%
Kg was finely pulverized with a ball mill to make the proportion of particles of 200 mesh or less to 80%. Of these, 0.5 K9 is 48
Carbonization was carried out at 0C for 1.2 hours to obtain 14 g of tar, and 0.5 kg of the remaining raw lignite was subjected to non-A pressure dehydration treatment at 380C for 1.2 hours. This treated coal was made into a 30% water slurry, and lignite particles were agglomerated using tar as a binder. The lignite after dehydration had a high quality moisture content of 8.9% and ash content of 3.9%.

Example 4 Lignite was produced in the same manner as in Example 1, except that lignite with a moisture content of 21% and an ash content (dry basis) of 21% was used, and 40% of the total amount was carbonized to obtain tar with a ratio of 7% to the coal. The length has been improved. The lignite after dehydration had a high quality moisture content of 14% and ash separation of 7%.

<Example 5> Example 1 except that the raw lignite used in Example 1 was used, and the entire amount was carbonized to distill tar of 8 wt% based on the coal.
The same process was performed. The moisture content of lignite after reforming is 7
．． 5%, and the ash content was 6.0%, which was high quality.

As described above, according to the present invention, the moisture content of low-rank coal is reduced to a few percent to a few percent, and at the same time deashing is performed, making it possible to produce high-quality coal without the risk of spontaneous combustion. This modified coal is not only convenient for transportation and storage, but also has the effect of being a high-grade coal with a low calorific value per unit weight.

[Brief explanation of drawings]

Claims (1)

[Claims] 1. A step of pulverizing coal, carbonizing a part of the pulverized coal to distill out water and tar, and non-evaporative heating the remaining coal to remove water content. a step of mixing the carbonized coal and the non-evaporative heating coal with water to form an aqueous slurry and adding the tar to agglomerate the coal particles; and a step of removing the agglomerated coal particles from the water. A method for reforming coal, comprising a step of separating. 2. A step of pulverizing coal, a step of carbonizing the pulverized coal to extract water and tar, and mixing water with the carbonized coal to form an aqueous slurry and adding the tar. A method for reforming coal, comprising the steps of aggregating coal particles and separating the agglomerated coal particles from water.