Method for preparing coal water slurry by blending gasified fine slag residual carbon and gasified coal

Abstract

The invention discloses a method for jointly preparing coal water slurry by blending gasified fine slag residual carbon and coal for gasification, which comprises the following steps: S1, adding water into gasified fine slag in a black water sedimentation tank, and mixing to obtain a mixed material; s2, carrying out carbon-ash separation on the mixed material in the S1 to obtain residual carbon concentrate and tailings; and S3, mixing the residual carbon concentrate obtained in the S2 with coal for gasification, a coal water slurry additive and water in proportion, and grinding in a ball mill to obtain the coal water slurry. According to the gasification fine slag carbon ash flotation separation method, the gasification waste water is adopted, enrichment and recovery of low-ash residual carbon and high-ash mineral particles can be achieved, meanwhile, pollutants in the gasification waste water can be treated through the porous adsorption performance of the gasification slag, and meanwhile the separation effect is enhanced through the trapping and foaming performance of the pollutants in the gasification waste water. By adopting the technical scheme, reduced emission and resource utilization of the gasified fine slag can be effectively realized, and meanwhile, pulping raw materials are saved.

Description

Technical Field

[0001] The invention relates to the field of solid waste treatment and recycling, and in particular to a method of preparing water-coal slurry by mixing gasification fine slag and residual carbon with gasification coal. Background Art

[0002] my country's resource endowment is characterized by "rich in coal, poor in oil, and little gas". It is estimated that by 2050, the proportion of coal in the national fossil energy consumption will remain above 50%. The efficient and clean use of energy has promoted the development of the coal chemical industry. In coal mining, washing and coal chemical utilization, a large amount of gasification slag solid waste and coal gasification wastewater will be generated and need to be treated. The coal gasification process mainly includes two parts: one is the removal of water from coal powder or gasified water-coal slurry at high temperature and pyrolysis to remove volatiles to form coal coke; the other is the reaction of coal coke in the gasification atmosphere to form coal gas. The minerals in the coal undergo homogeneous and heterogeneous reactions under high temperature and pressure to form amorphous slag, which is highly mixed, closely embedded, and densely melted with the residual coal coke in the co-combustion zone, and then discharged from the gasifier with raw coal gas or liquid ash. The products discharged from the gasifier mainly include two parts, namely raw coal gas and solid by-products. Solid by-products mainly include two parts: one is the gasification fly ash (dry ash) discharged with the raw coal gas, and the other is the gasification ash discharged from the gasifier through the ash release mechanism from the liquid ash layer. The gasification ash is then quenched in the quenching pool, and the dense, high-density, grinding-resistant glassy, ​​spherical, and spheroidal particles are discharged from the lock bucket with the bottom flow, which is called coarse slag (lock bucket slag); the irregular, flocculent, spherical, and spheroidal particles with fluffy structure, developed pores, low density, and high carbon content enter the sedimentation tank with the black water, and are mixed with the washed fly ash and filtered for dehydration. The filter cake is the gasification fine slag. Generally speaking, the fine slag has a higher carbon content than the coarse slag.

[0003] As an important clean coal technology, the coal-water slurry process is also one of the key technologies in the field of coal chemical energy. It provides an effective way to achieve clean and efficient use of coal. Coal-water slurry fuel is a low-pollution, high-efficiency, pipeline-transportable coal-based fluid fuel that replaces oil and is formed by strong stirring of 60% to 70% coal powder, 30% to 40% water and less than 1% additives. At present, the coal used for slurrying is mainly bituminous coal such as non-sticky coal and weakly sticky coal. However, with the rise in energy prices and resource shortages, the development of low-rank coal slurrying technology and the expansion of water-coal slurry raw material selection have become important development directions for the water-coal slurry industry. The gasification fine slag contains a lot of residual carbon. It is beneficial to resource utilization and environmental protection to be able to use it in the preparation of water-coal slurry after sorting. However, due to the high calorific value and poor slurrying property of the gasified fine slag, the free volume between the coal slurry particles decreases with the increase of concentration, the contact probability between the coal particles increases, and the agglomeration and friction coefficient between the coal particles greatly increase, which easily makes the water-coal slurry viscosity larger and the fluidity worse, resulting in the precipitation of the water-coal slurry, obstructed transportation, poor atomization effect, and low fuel efficiency. CN115820313A discloses a method for preparing water-coal slurry based on gasified slag, and the disclosed water-coal slurry preparation method comprises the following steps: adding black water or water to the gasified coarse slag, raw material coke, and emulsified water agent to a mill through different feed ports for grinding and mixing to obtain water-coal slurry. The method directly mixes the reagent and the material in a ball mill to obtain a high-viscosity water-coal slurry. However, the disadvantage is that the mineral component of the gasified slag added in the ball mill is high, which causes serious wear on the equipment. Most of the existing technologies are to treat and utilize the gasified fine slag separately in a harmless, functional, and resource-based manner, and the existing treatment schemes still have problems such as environmental pollution, low utilization rate, and dangerous operation.

[0004] Based on the above analysis, a method for preparing water-coal slurry that can achieve the enrichment and recovery of low-ash residual carbon and high-ash mineral particles, effectively achieve the reduction of gasification fine slag emissions and resource utilization, while saving pulping raw materials and producing safer and environmentally friendly products is urgently needed in the industry. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention provides a method for preparing water-coal slurry by combining residual carbon from gasification fine slag and coal for gasification, so that the carbon and ash of the gasification fine slag can be separated first, and the content of high-hardness minerals can be reduced to meet the ash requirement for preparing gasification slurry. It is also proposed that the residual carbon concentrate after sorting the gasification fine slag can be directly mixed and ground with the coal for gasification to prepare water-coal slurry, which meets actual production needs.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention first provides a method for preparing water-coal slurry by sorting and extracting carbon from gasification fine slag and then blending with gasification coal, comprising the following steps:

[0008] S1: wastewater is added to the coal gasification fine slag to obtain a mixed material;

[0009] S2: adding a collector and a frother to the mixed material in S1 to perform carbon ash flotation separation to obtain residual carbon concentrate and tailings;

[0010] S3: The residual carbon concentrate obtained in S2 is mixed with coal for gasification, water-coal slurry additive and water in proportion, and then put into a ball mill for grinding to obtain water-coal slurry.

[0011] Furthermore, the wastewater in step S1 is selected from: clean water, gasification wastewater, and organic wastewater, and is added in an amount such that the content of coal gasification fine slag in the mixed material reaches 40-150 g / L.

[0012] Furthermore, the slurry solid content concentration of the mixed material in step S1 is 40 to 150 g / L.

[0013] Furthermore, the collector in step S2 is fuel oil, and the amount added is 16kg / t to 28kg / t based on the dry weight of the coal gasification fine slag.

[0014] Furthermore, the foaming agent in step S2 is an alcohol, and the added amount is 4kg / t to 14kg / t based on the dry weight of the coal gasification fine slag.

[0015] Furthermore, the mass ratio of the residual carbon concentrate to the gasification coal in step S3 is 1:1 to 1:9.

[0016] Furthermore, the coal water slurry additive in step S3 is selected from any one or more of naphthalene-based, lignin-based, and polycarboxylic acid-based additives.

[0017] Furthermore, the amount of the water-coal slurry additive added in step S3 is 0.3% to 1.5% of the total weight of the residual carbon concentrate and the gasification coal on a dry basis.

[0018] The invention also discloses a water-coal slurry prepared according to any one of the above preparation methods.

[0019] Compared with the prior art, the beneficial technical effects of the present invention are:

[0020] The flotation separation of carbon ash from gasified fine slag of the present invention uses gasified wastewater to achieve the enrichment and recovery of low-ash residual carbon and high-ash mineral particles. At the same time, the porous adsorption performance of gasified slag can be used to treat pollutants in gasified wastewater, and the capture and foaming performance of gasified wastewater pollutants can be used to enhance the separation effect. By adopting the above technical solution, the emission reduction and resource utilization of gasified fine slag can be effectively achieved, while saving pulping raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments are briefly introduced below.

[0022] Figure 1 The present invention is a schematic flow chart of an embodiment of preparing water-coal slurry by mixing gasification fine slag and residual carbon with gasification coal. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with specific embodiments.

[0024] Example 1

[0025] S1: Add organic wastewater (phenol content is 4000 mg / L) to the bottom flow of the gasification fine slag sedimentation tank to mix and obtain a mixed material.

[0026] S2: Add diesel (collector) in an amount of 22 kg / t and methyl isobutyl carbinol (foaming agent) in an amount of 12 kg / t to the mixed material in S1, and perform carbon ash flotation separation to obtain residual carbon concentrate and tailings;

[0027] S3: The residual carbon concentrate obtained in S2 is mixed with the coal for gasification in a ratio of 1:1, and is added into a ball mill together with a naphthalene dispersant (added in an amount of 1%) and organic wastewater for grinding to obtain water-coal slurry.

[0028] The solid concentration of gasified fine slag in the black water in S1 is 40 g / L.

[0029] The coal used for gasification in S3 is a kind of Xinjiang lignite.

[0030] The ash content of the residual carbon concentrate from the flotation of gasified slag in this embodiment is 37.13%, the yield is 61.37%, the concentration of the water-coal slurry is 56.41%, and the viscosity is 963.3 mPa·s.

[0031] Example 2

[0032] Different from the water source of specific embodiment 1

[0033] S1: Add gasification wastewater (ammonia nitrogen content of 400 mg / L) to the bottom flow of the gasification fine slag sedimentation tank to mix and obtain a mixed material.

[0034] S2: Add diesel (collector) in an amount of 22 kg / t and methyl isobutyl carbinol (foaming agent) in an amount of 12 kg / t to the mixed material in S1, and perform carbon ash flotation separation to obtain residual carbon concentrate and tailings;

[0035] S3: The residual carbon concentrate obtained in S2 is mixed with the coal for gasification in a ratio of 1:1, and added with a naphthalene dispersant (added in an amount of 1%) and clean water into a ball mill for grinding to obtain water-coal slurry.

[0036] The solid concentration of gasified fine slag in the black water in S1 is 40 g / L.

[0037] The coal used for gasification in S3 is a kind of Xinjiang lignite.

[0038] The ash content of the residual carbon concentrate from the flotation of gasified slag in this embodiment is 33.44%, the yield is 49.82%, the slurry concentration of the water-coal slurry is 58.56%, and the viscosity is 774.7 mPa·s.

[0039] Example 3

[0040] S1: Add clean water to the bottom flow of the gasification fine slag sedimentation tank and mix to obtain a mixed material.

[0041] S2: Add kerosene (collector) in an amount of 22 kg / t and methyl isobutyl carbinol (foaming agent) in an amount of 12 kg / t to the mixed material in S1, and perform carbon ash flotation separation to obtain residual carbon concentrate and tailings;

[0042] S3: The residual carbon concentrate obtained in S2 is mixed with the coal for gasification in a ratio of 1:1, and is added into a ball mill together with a naphthalene dispersant (added in an amount of 1%) and water for grinding to obtain a water-coal slurry.

[0043] The solid concentration of gasified fine slag in the black water in S1 is 40 g / L.

[0044] The coal used for gasification in S3 is a kind of Xinjiang lignite.

[0045] The ash content of the residual carbon concentrate from the flotation of gasified slag in this embodiment is 36.17%, the yield is 49.09%, the slurry concentration of the water-coal slurry is 58.23%, and the viscosity is 852.1 mPa·s.

[0046] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art.

[0047] The above examples are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Any simple modification, change and equivalent transformation made to the above embodiments according to the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing water-coal slurry by mixing gasification fine slag and residual carbon with gasification coal, comprising: S1: wastewater is added to the coal gasification fine slag to obtain a mixed material; S2: adding a collector and a frother to the mixed material in S1 to perform carbon ash flotation separation to obtain residual carbon concentrate and tailings; S3: The residual carbon concentrate obtained in S2 is mixed with coal for gasification, water-coal slurry additive and water in proportion, and then put into a ball mill for grinding to obtain water-coal slurry.

2. The method according to claim 1, wherein: The wastewater in step S1 is gasification wastewater and organic wastewater, and the added amount is such that the content of coal gasification fine slag in the mixed material reaches 40-150 g / L.

3. The method according to claim 1, wherein: The solid content concentration of the slurry of the mixed material in step S1 is 40 to 150 g / L.

4. The method according to claim 1, wherein: The collector in step S2 is fuel oil, and the amount added is 16kg / t to 28kg / t based on the dry weight of the coal gasification fine slag.

5. The method according to claim 1, wherein: The foaming agent in step S2 is alcohol, and the added amount is 4kg / t to 14kg / t based on the dry weight of the coal gasification fine slag.

6. The method according to claim 1, wherein: The mass ratio of the residual carbon concentrate to the gasification coal in step S3 is 1:1 to 1:

9.

7. The method according to claim 1, wherein: In step S3, the water-coal slurry additive is selected from any one or more of naphthalene-based, lignin-based, and polycarboxylic acid-based additives.

8. The method according to claim 1, wherein: The amount of the water-coal slurry additive added in step S3 is 0.3% to 1.5% of the total weight of the residual carbon concentrate and the gasification coal on a dry basis.

9. A coal-water slurry prepared according to the method of any one of claims 1 to 8.

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