JPS61126198A - Process for preparing deashed high-concentration slurry - Google Patents

Abstract

PURPOSE:To effectively utilize water and to recover fine coal, thus economically obtaining the titled slurry, by utilizing specified waste water as feed water for wet pulverization and as concn.-adjusting water for flotation to carry out coarse coal classification in combination with fine coal flotation. CONSTITUTION:Feed coal 11 crushed to a particle size <=100mm is wet is screened with a screen 1 and the oversize product 13 is sent to a coarse coal classifier 2 and classified to separate into low-ash coal 17 and intermediate-ash coal 16 while removing high-ash coal 15 in the feed coal 11.Coal recovered from slurry 18 prepd. by mixing coal powder slurry contg. the undersize fine coal with waste water from the classifier 2 and introduced into a fine coal dehydrator 5, is mixed with the intermediate-ash coal 16 to prepare a slurry 19 of 5-18% concn. flotation in a wet pulverizer 5. The slurry 19 is introduced into a flotation means 6 and the refined coal froth is sent to a fine coal dehydrator 7 in the form of froth 20 of 15-30% concn. On the other hand, after crushed with a crusher 8, the low-ash coal 17 is mixed with the froth 20 to obtain the titled slurry 24 of concn. >=60%, having a desired particla size in a wet pulverizer 9. Waste water from the dehydrator 3 is also utilized as feed water to the pulverizer 5 and flotation means 6.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing a highly concentrated deashed slurry, and the present invention relates to a process for producing a highly concentrated deashed slurry. The aim is to

Coal liquefaction, gasification, O
Fluidization technologies such as OM are being developed, and one of these fluidization technologies is a highly concentrated coal-water slurry. This slurry contains 70 to 90 coal particles of 74μ or less.
Finely pulverized until it contains about 65-75% coal and 3% water.
By adding a slurrying agent at a weight ratio of 5 to 25%, the coal has fluid properties even at the above-mentioned coal concentration, and has the advantage that it can be handled in the same way as conventional petroleum fuel.

However, even though it has become possible to process coal into a slurry in the same way as petroleum fuel, this does not mean that the problem of disposing of the ash content in coal has been solved. That is, during combustion, ash not only wears out the boiler walls and reduces combustion efficiency, but also makes transportation costs uneconomical.

Therefore, when using raw coal with a relatively high ash content, a method has been proposed in which the coal is finely pulverized in order to reduce the ash content, and then the entire amount is deashed. However, when this method is adopted, the pulverized coal deashing processing equipment becomes large and
Not only does the treatment cost become high, but a sufficient deashing effect cannot be obtained.

Therefore, as an improvement plan, we combined a deashing method that consists of coarse grain sorting and partial pulverized coal flotation of the resulting product, which is expected to be economical and have a good deashing effect, even if coal with a relatively high ash content is used as raw coal. proposed a method for producing a high-concentration slurry (Japanese Patent Application No. 58-89699).

This method is Q, 5M cheaper than raw coal! Coarse coal excluding pulverized coal of I or less is separated by specific gravity, high ash coal with high specific gravity is discarded as hard, two products of low ash coal and medium ash coal are obtained, and a mixed coal of this medium ash coal and pulverized coal is produced. A highly concentrated slurry is produced from clean coal floss and low ash coal obtained by pulverization and flotation and deashing.

In this method, a large amount of washing water is used to separate powdered coal of 0.5 or less size from raw coal, and a large amount of water is used when a jig or the like is used for coarse particle sorting. A considerable amount remains. In addition, a large amount of water is required during wet pulverization of mixed coal of medium ash coal and powdered coal and for concentration adjustment for flotation, and some of this water is discharged during the dehydration process of flotation. ing.

As mentioned above, each step of this slurry production method involves the use of a large amount of water and waste water, so the present invention makes it possible to effectively utilize these waste water in the predetermined steps and also to recover granular coal. The purpose is to improve the economic efficiency of producing highly concentrated slurry.

The following will explain the embodiment of the present invention according to the flow sheet shown in FIG.

The raw coal 11, which is usually crushed to a size of 1001111 or less, preferably 5Qmi+ or less, is wet-sieved using a pulverized coal screen 1. The sieved souvenir 13 is sent to a coarse grain sorter 2, where it is coarse grained, high ash coal 15 mixed in raw coal is removed, and it is sorted into low ash coal 17 and medium ash coal 16.

The pulverized coal slurry containing the fine coal under the sieve is mixed with the waste water from the coarse grain separator 2 and introduced into the pulverized coal dehydrator 3 as a slurry IJ-18, and the dehydrated and recovered coal is crushed in the crusher 4. It is mixed with medium ash charcoal. This powdered coal dehydrator 3
Normally, unrecovered fine coal remains in the wastewater.

This mixed coal is sent to a wet pulverizer 5 and pulverized into a slurry of preferably 10 to 50%. The slurry obtained by this wet pulverization is suitable for flotation with a concentration of 5 to 15%.
It is introduced into the flotation machine 6 as a slurry 19 diluted to . The flotation froth clean coal is recovered as 70s 20 at a concentration of 15-30% and then transferred to the pulverized coal dehydrator 7.

On the other hand, after the low ash coal 111j is drained, it is introduced into the crusher 8 and crushed into 39ii+ or less, preferably 5 or less,
The dehydrated slurry 24 is mixed with the dehydrated 70s 20 and introduced into a wet pulverizer 9 together with a dispersant to produce a highly concentrated demineralized slurry 24 having a desired particle size and a 6 degree of 60% or more.

Water 12 introduced into pulverized coal screen 1 and coarse particle sorter 2
．． Generally speaking, the former 12 is equal to the amount of raw coal input, and the latter 1
4 is about 2.0% of the top product 13. ．． It is 5 times more. Coarse grain sorter 2
Most of the water in the waste water and the pulverized coal slurry IJ- is discharged as P liquid from the pulverized coal dehydrator 3.

This dehydrated P liquid is supplied and used as water for wet pulverization of medium ash coal and powdered coal, and water for concentration adjustment in flotation. This dehydrated liquid f contains fine coal that was not captured by the powder coal dehydrator 3, but since it is supplied as water for the wet pulverization and concentration adjustment, the unrecovered fine coal becomes medium ash coal. It can be recovered as clean coal through flotation along with mixed pulverized coal.

In addition, since the tail 21 of the flotation machine 6 contains a large amount of natural substances, it is supplied to the thickener 10, and the clarified liquid (water from which ash has been removed) is screened together with the waste water 22 of the pulverized coal dehydrator 7. The water is recycled and reused as water 12 and water 14 for the coarse particle sorter.

In this example, the pulverized coal slurry containing fine coal particles, the waste water from the coarse particle sorter, and the whole pulverized coal dehydrator 3 were used. If pulverization by the pulverizer 5 is not necessary, the pulverized coal dehydrator 3 may not be provided. At this time, for example, the pulverized coal slurry may be directly led to the flotation machine 6, and the waste water from the coarse particle separator may be used as water for adjusting the concentration of the medium ash coal 16 in the wet pulverizer 5 and the flotation machine 6.

In FIG. 1, the solid line indicates slurry with a concentration of 30% or more, and the broken line indicates slurry with a concentration of less than 30%.

Next, an experimental example will be shown.

The sample charcoal I kg was crushed to a particle size of IQIII or less, Q,
5 Sieve off the powdered coal (0.5 mm or less) by tightening the sn.
High ash content coal with a specific gravity of 1.6 or more is produced by floating and sinking the sieved coal.
Low ash coal with a specific gravity of 1.3 or less and medium ash coal with an intermediate specific gravity were obtained. After crushing this medium ash coal to 3N or less, the above-mentioned sieved pulverized coal was mixed and pulverized to a particle size of 200 mesh or less 75% to obtain 330g of pulverized coal, which was made into a slurry with a solid concentration of 10% and flotated. I did an experiment. The resulting flotation froth clean coal (20% slurry) L525. li+
A dehydration test was carried out by a Bunner Rotator. The flow of coal amount based on the results obtained from the above pulverized coal separation, flotation and sedimentation separation, pulverized coal flotation, and flotation 70% dehydration, as well as the amount of water used for pulverized coal separation and when using a jig for coarse particle sorting, are set. , the water amount balance was established and the results are shown in Table 1 in weight units with the amount of sample coal being 100. Slaur U-18, which is a combination of pulverized coal slurry and waste water from the coarse grain sorter, is 320.6 when the amount of raw coal is 100, and if the entire amount is supplied to wet crushing water and concentration adjustment water for flotation, it becomes slurry for flotation. The concentration of J-19 was 9.1%, giving a slurry concentration suitable for flotation. As a result of flotation, clean coal 70s and tails are obtained,
The dewatering tail 22 of clean coal 70s is 93.3, and the flotation machine tail 21 is 190.7. This total is recycled and reused as water for the pulverized coal screen and coarse grain separator. Since a total of 41.7 liters of water accompanying the water flowing into the product deashing high concentration slurry, high ash coal and tail sludge 23 is discharged outside the system, it is sufficient to supply the same amount as make-up water. Become. If fresh water is used for pulverized coal screen water, coarse grain separator water, wet pulverization water, and flotation dilution water without circulation, the total amount of water used will be approximately 600. Certain granular coal cannot be recovered, resulting in extremely poor economic efficiency.

Table 1 In addition, Table 1 shows the amount of raw coal (bellows base) in weight units.
It shows the balance of coal and water set to 0, the solids concentration of the slurry, and the water content of the coal.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet showing an embodiment of the present invention. In the diagram:

Claims (1)

[Claims] 1) Separate raw coal into pulverized coal and coarse coal, guide the coarse coal to a coarse grain separator, and obtain two products, low ash coal and medium ash coal, based on the difference in specific gravity. is mixed with the pulverized coal, followed by wet pulverization, flotation and deashing, and a medium concentration pulverized coal slurry is created in the dehydration process,
In the production of deashed high-concentration slurry, in which the slurry and low ash coal are pulverized to produce a slurry, the pulverized coal screen and coarse grain separator wastewater are used as water for wet pulverization of mixed coal of medium ash coal and pulverized coal, and for flotation. Production process of highly concentrated demineralized slurry used as concentration adjustment water. 2) The raw coal was separated into powdered coal and coarse coal, and the coarse coal was introduced into a coarse grain separator to obtain two products, low ash coal and medium ash coal, based on the difference in specific gravity, and the medium ash coal was mixed with the powdered coal. After wet pulverization and flotation deashing, a medium-concentration pulverized coal slurry is created in the dehydration process.
In the production of deashed high-concentration slurry, in which the slurry and low ash coal are pulverized to produce a slurry, the pulverized coal screen and coarse grain separator wastewater are used as water for wet pulverization of mixed coal of medium ash coal and pulverized coal, and for flotation. A process for producing a highly concentrated deashing slurry, which is characterized in that the waste water from the flotation and dewatering processes is recycled and reused as water for a powder coal screen and water for a coarse grain sorter.