High-concentration coal water slurry and preparation method and application thereof

Abstract

The invention discloses high-concentration coal water slurry and a preparation method thereof. The concentration of the high-concentration coal water slurry is 63-75wt%, and the mass ratio of dry basis coarse particle pulverized coal to medium particle pulverized coal to fine particle pulverized coal to additive in the coal slurry is (10-60): (10-50): (5-50): (0.5-5). The low-ash coal slurry withthe solid content of 10%-35% and the ash content of 1%-10% is prepared by taking inferior low-quality coal as a raw material through a micro-ore separation technology. The low-ash coal slurry is usedas a medium-particle coal slurry raw material and a fine-particle coal slurry raw material, and coarse-particle pulverized coal which is obtained by grinding clean coal and has the particle size of 150-500 microns is added into the low-ash coal slurry, high-concentration coal water slurry is prepared by adjusting particle size distribution of pulverized coal to be in three-peak distribution, the concentration range of the high-concentration coal water slurry is 63-75 wt%, the apparent viscosity of the high-concentration coal water slurry is 850-1300 mPa.s, the fluidity of the high-concentration coal water slurry is B or above, and the stability of the high-concentration coal water slurry is in level B or above. Low-ash coal slurry obtained by upgrading low-quality coal through a micro-mineral separation technology does not need to be subjected to filter-pressing dehydration treatment, re-crushing and re-dispersing of filter-pressing clean coal filter cakes do not need to be considered,and the cost can be greatly saved by directly pulping the low-ash coal slurry through micro-mineral separation.

Description

technical field [0001] The invention belongs to the field of clean utilization of coal resources, and relates to a preparation method of high-concentration coal-water slurry and its application. Background technique [0002] Energy is the material basis for human survival and development. my country's energy structure is manifested as: oil and natural gas and other resources are poor, and coal resources are relatively rich. my country is a country with a large amount of energy, but it is also a poor country with a low per capita share of energy resources. It is one of the few countries in the world where coal resources are the main energy source. In the past 20 years, the proportion of coal in total energy consumption has gradually increased from 68.5% in 2000 to 72.5% in 2007. From 2007 to 2011, the proportion fluctuated slightly at around 70%. From 2012 to 2018 The proportion of coal in total energy consumption decreased by an average of 1.6% (National Bureau of Statist...

AI Technical Summary

Problems solved by technology

This kind of pulping process has many crushing and crushing processes, high energy consumption and high cost

Moreover, the quality of the prepared coal-water slurry is limited by the raw coal grade, so it is difficult to produce a high-grade coal-water slurry with high concentration and low ash, which may not meet the raw material requirements of the coal gasifier

The other is to use coal slime to prepare coal-water slurry, but the floated clean coal obtained by coal slime flotation contains a large amount of water (70-90%), which needs to be removed by processes such as flotation clean coal concentration and filter press extraction. Pulp can only be made after the moisture content is high, again increasing the cost of comprehensive utilization of coal slime

For example, after coal preparation using conventional flotation technology, the solid content of the flotation clean coal slurry obtained is about 20%, and the next step is dehydration in a filter press, which must be dehydrated to a solid content of about 75%. If the solid content is lower than this, the filter cake Not shaped, the filter press is inconvenient to operate (for example, the filter cake cannot be easily unloaded from the filter press), and subsequent transportation is inconvenient (the filter cake cannot be easily transported by a belt)

However, at a solid content of 75%, the filter cake has lost its fluidity, and qualified coal-water slurry products require moderate viscosity of coal-water slurry to be sent to boilers or gasifiers through the pumping process. Therefore, after the dehydration process, It is also necessary to replenish water, add dispersant, and reduce the solid content to about 60%, so that the viscosity can reach the standard and meet the needs of transportation

Dehydration first and then replenishment, resulting in increased processes, equipment, and energy consumption

Therefore, using the existing pulping process to obtain clean coal through coal slime flotation to prepare coal-water slurry has the following problems: 1. It needs to undergo filter press dehydration treatment, stirring and dispersing filter cake technology, and the pulping cost is high; 2. The slurry raw material comes from flotation clean coal, and the particle size distribution is not easy to control, resulting in poor particle size distribution, which makes it difficult to form a high accumulation efficiency, and produce high-concentration coal-water slurry

[0006] In addition, most of the existing coal-water slurry production methods have problems such as small increase in coal slurry concentration, complicated process, poor operability, and high energy consumption.

On the other hand, even after the concentration is increased, the viscosity, stability and fluidity of the coal-water slurry are greatly reduced, and it cannot be used as a raw material for the coal-water slurry boiler or gasifier at all.

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