Method for controlling diffusion and migration of underground gasification residual pollutants

Abstract

The invention relates to a method for controlling diffusion and migration of underground gasification residual pollutants. The method for controlling the diffusion and the migration of underground gasification residual pollutants comprises steps of building a bottom impervious layer, building a middle supporting layer and building a top waterproof layer. The method for controlling the diffusion and the migration of the underground gasification residual pollutants has the advantages of being simple in structure and convenient to construct; controlling the migration of the pollutants due to the facts that the impervious layer is a bentonite impervious layer and strong in pollutant retaining in gasified waste water and the bentonite are inorganic minerals, cheap and easy to obtain and good in pollutant retaining and absorption capability; and preventing clean water source from entering into an underground gasification waste water area through the top water proof layer, isolating the clean water source from the underground gasification waste water area and preventing surface water permeating into the underground gasification waste water area through a rock stratum and contacting with gasification waste water to be polluted.

Description

technical field [0001] The invention relates to the field of underground coal gasification, in particular to a method for controlling the diffusion and migration of underground gasification residual pollutants, and is a prevention and control method for treating underground gasification wastewater residual pollutants. Background technique [0002] Underground coal gasification is a process in which underground coal seams are used as raw materials, air, oxygen and steam are used as gasification agents, and combustible gases are generated through the thermal and chemical effects of gasification agents and coal. Compared with the traditional surface gasification process, underground coal gasification has the characteristics of safety, high efficiency and low investment. However, the pyrolysis section of underground coal gasification will inevitably produce pollutants, including ammonia nitrogen, phenols, heavy metals and polycyclic aromatic hydrocarbons. These substances will ...

AI Technical Summary

Problems solved by technology

[0009] Existing technology 1 uses a chemical method to oxidize phenolic pollutants in underground gasification wastewater with a certain concentration of hydrogen peroxide, and the pollutants removed are relatively single

Hydrogen peroxide is difficult to oxidize heavy metal ions and ammonia nitrogen. If heavy metal ions and ammonia nitrogen migrate into the groundwater system, it will also cause serious pollution.

Moreover, the price of hydrogen peroxide is not low, which will increase the cost of underground gasification wastewater treatment.

[0010] Existing technology 2 uses acidification and biochemical methods to treat underground gasification wastewater. The disadvantage is that it is difficult to carry out hydrolysis and acidification in the deep underground gasification burn-out area, and the residual acid will bring further pollution, and biological contact is carried out deep underground. The oxidation step is also more difficult

[0011] Prior art 3 and prior art 4 are mainly aimed at the above-ground gasification process and cannot be applied underground. It is difficult to establish extraction and rectification devices in the deep underground of prior art 3. The price of activated coke used in prior art 4 More expensive, intermediate steps are also difficult for anaerobic and aerobic biological treatment

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