Abstract: The present disclosure provides an artificial dam of a distributed coal mine underground reservoir and its constructing method. The artificial dam comprises a support layer (10), an anti-seepage layer (20), and a concrete structure layer (30) that are successively formed in an auxiliary roadway (1) from inside to outside, the concrete structure layer (30) being embedded into a security coal pillar (2) and/or surrounding rock (3) around the auxiliary roadway (1). Because the concrete structure layer (30) is embedded into the security coal pillar (2) and/or the surrounding rock (3) around the auxiliary roadway (1), the artificial dam is combined to the security coal pillar (2) to together form a dam for an underground reservoir. Due to multi-layer design, anti-seepage performance and structural strength of the dam can meet the water storage requirements of the underground reservoir.

Abstract: An opencast coal mine underground water reservoir comprising an impermeable layer and, provided below the impermeable layer, a water storage space and a purification layer. The water storage space comprises a first water storage space and a second water storage space. The purification layer comprises a first purification layer and a second purification layer. The first purification layer is provided horizontally in the water storage space and divides the water storage space into the first water storage space and the second water storage space. The first water storage space is provided below the impermeable layer and between same and the first purification layer. The second water storage space is provided below the first water storage space and the bottom of the second water storage space is provided at the bottom of the opencast coal mine underground water reservoir. The second purification layer is provided vertically within the second water storage space.

Abstract: The present disclosure provides an artificial dam of a distributed coal mine underground reservoir and its constructing method. The artificial dam comprises a support layer (10), an anti-seepage layer (20), and a concrete structure layer (30) that are successively formed in an auxiliary roadway (1) from inside to outside, the concrete structure layer (30) being embedded into a security coal pillar (2) and/or surrounding rock (3) around the auxiliary roadway (1). Because the concrete structure layer (30) is embedded into the security coal pillar (2) and/or the surrounding rock (3) around the auxiliary roadway (1), the artificial dam is combined to the security coal pillar (2) to together form a dam for an underground reservoir. Due to multi-layer design, anti-seepage performance and structural strength of the dam can meet the water storage requirements of the underground reservoir.

Abstract: The present disclosure provides an artificial retaining dam of coal mine underground reservoir. The artificial retaining dam (30) is embedded into a security coal pillar (2) and surrounding rock (3) around an auxiliary roadway (1), the cross section of the artificial retaining dam (30) is an arc, and a concave of the arc artificial retaining dam (30) faces the underground reservoir. The disclosure also disclosed a method for connecting a security coal pillar, surrounding rock, and an artificial retaining dam for a coal mine underground reservoir. The retaining dam improves sliding-resistant performance of an artificial retaining dam, and can effectively cushion the impact to the dam bodies due to suddenly increased water pressure.

Abstract: Disclosed is a method for distributed storage and use of mine groundwater. The method comprises the following steps: A. prospecting an area of an underground space to be mined, and acquiring data on the bedrock geology of the strata; B. observing the mine groundwater, and acquiring the conditions of the flow distribution, water quality data and water pressure data for the mine groundwater; C. designating one or more goaf spaces through which mine groundwater cannot permeate as a water storage space of a distributed underground reservoir according to the data on the bedrock geology of the strata acquired in step A and the conditions of the flow distribution, water quality data and water pressure data for the mine groundwater acquired in step B; and D. after the designated water storage space is formed, mine groundwater generated when mining a mining face adjacent thereto naturally seeps into the water storage space.

Abstract: An opencast coal mine underground water reservoir comprising an impermeable layer and, provided below the impermeable layer, a water storage space and a purification layer. The water storage space comprises a first water storage space and a second water storage space. The purification layer comprises a first purification layer and a second purification layer. The first purification layer is provided horizontally in the water storage space and divides the water storage space into the first water storage space and the second water storage space. The first water storage space is provided below the impermeable layer and between same and the first purification layer. The second water storage space is provided below the first water storage space and the bottom of the second water storage space is provided at the bottom of the opencast coal mine underground water reservoir. The second purification layer is provided vertically within the second water storage space.

Abstract: Disclosed is a method for distributed storage and use of mine groundwater. The method comprises the following steps: A. prospecting an area of an underground space to be mined, and acquiring data on the bedrock geology of the strata; B. observing the mine groundwater, and acquiring the conditions of the flow distribution, water quality data and water pressure data for the mine groundwater; C. designating one or more goaf spaces through which mine groundwater cannot permeate as a water storage space of a distributed underground reservoir according to the data on the bedrock geology of the strata acquired in step A and the conditions of the follow distribution, water quality data and water pressure data for the mine groundwater acquired in step B; and D. after the designated water storage space is formed, mine groundwater generated when mining a mining face adjacent thereto naturally seeping into the water storage space.

Abstract: Disclosed is a method for extracting gallium from fly ash, which comprises the following steps: crushing the fly ash and removing Fe by magnetic separation; then dissolving it by using hydrochloric acid to obtain hydrochloric acid leachate; adsorbing gallium contained in the hydrochloric acid leachate with macro-porous cationic resin, followed by eluting to obtain an eluent containing gallium; adding masking agent to mask ferric ion to obtain an eluent containing gallium after masking; adsorbing gallium in the eluent containing gallium after masking with macro-porous cationic resin, followed by eluting to obtain a secondary eluent; adding sodium hydroxide solution into the secondary eluent to react; filtering and removing precipitates after reaction, and then concentrating the filtrate and electrolyzing to obtain metal gallium. The method simplifies the process and improves extraction efficiency of gallium.

Abstract: Disclosed is a method for extracting gallium from fly ash, which comprises the following steps: crushing the fly ash and removing Fe by magnetic separation; then dissolving it by using hydrochloride acid to obtain hydrochloric acid leachate; adsorbing gallium contained in the hydrochloric acid leachate with macro-porous cationic resin, followed by eluting to obtain an eluent containing gallium; adding masking agent to mask ferric ion to obtain an eluent containing gallium after masking; adsorbing gallium in the eluent containing gallium after masking with macro-porous cationic resin, followed by eluting to obtain a secondary eluent; adding sodium hydroxide solution into the secondary eluent to react; filtering and removing precipitates after reaction, and then concentrating the filtrate and electrolyzing to obtain metal gallium. The method simplifies the process and improves extraction efficiency of gallium.

Abstract: Disclosed is a method for extracting gallium from fly ash, which comprises the following steps: crushing the fly ash and removing Fe by magnetic separation; then dissolving it by using hydrochloride acid (2) to obtain hydrochloric acid leachate; adsorbing gallium in the hydrochloric acid leachate with macro-porous cationic resin, followed by eluting to obtain the eluent (5) containing gallium; adding sodium hydroxide (6) solution into the eluent containing gallium to react and obtaining sodium metaaluminate solution containing gallium (8); introducing CO2 into the sodium metaaluminate solution containing gallium (8) for carbonation, followed by separating gallium from aluminum and obtaining aluminum-gallium double salt (15) with the gallium to alumina mass ratio being more than 1:340; adding the aluminum-gallium double salt (15) into sodium hydroxide (17) to react, followed by alkalinity-adjustment concentration to obtain alkali solution containing gallium and aluminum; electrolyzing (10) the alkali solution