An assembly that fits within a ventilation shaft open to atmosphere and leading from underground ventilation ducts such as to subways prevents surface waters from flooding the underground ducts while maintaining the ventilation. The assembly fits in the ventilation shaft and houses a buoyant float in a chamber surrounding a passageway in fluid communication with the ventilation shaft. A grate covers the passageway. An outside wall of the chamber adjacent the ventilation shaft is open at top to atmosphere and allows flooding water into the chamber, buoying the float upward in the chamber, elevating the passageway above the flooding water. The chamber suitably has means for drainage and admission of flush water to flush flood water debris from the chamber through the drainage.

An assembly that fits within a ventilation shaft open to atmosphere and leading from underground ventilation ducts such as to subways prevents surface waters from flooding the underground ducts while maintaining the ventilation. The assembly fits in the ventilation shaft and houses a buoyant float in a chamber surrounding a passageway in fluid communication with the ventilation shaft. A grate covers the passageway. An outside wall of the chamber adjacent the ventilation shaft is open at top to atmosphere and allows flooding water into the chamber, buoying the float upward in the chamber, elevating the passageway above the flooding water. The chamber suitably has means for drainage and admission of flush water to flush flood water debris from the chamber through the drainage.

A device for integrated control of acid wastewater plugging and discharging of an abandoned mine includes an airtight wall, a central controller, a CO.sub.2 gas source, an agent bucket, a siphon pipe I and a liquid storage bucket are arranged on the outer side of the airtight wall, and a plurality of monitoring sensors are arranged in the inner side of the airtight wall, and the monitoring sensors are electrically connected to the central controller; and a flood discharge valve is arranged at the bottom of the airtight wall. The device is miniaturized and operates for a long time with low power consumption, thereby achieving long-term unattended operation and maintenance.

The disclosure provides a liquid taking device and a liquid taking method. The liquid taking device comprises a liquid taking bottle, a heavy ball and liquid taking ropes. The liquid taking bottle has a first mouth and a bottom opposite to the first mouth. The heavy ball is arranged in the liquid taking bottle. The liquid taking device can be controlled to reach different depths under the ground by the action of two liquid ropes. When the first mouth of the bottle is placed facing downward, the heavy ball blocks the first mouth of the bottle under its own gravity to prevent liquid leakage; when the first mouth of the bottle is turned upwards under the action of the liquid taking rope, the heavy ball falls onto the bottom of the bottle, such that an external liquid can flow into the liquid taking device, which has a good practical utility.

The disclosure provides a liquid taking device and a liquid taking method. The liquid taking device comprises a liquid taking bottle, a heavy ball and liquid taking ropes. The liquid taking bottle has a first mouth and a bottom opposite to the first mouth. The heavy ball is arranged in the liquid taking bottle. The liquid taking device can be controlled to reach different depths under the ground by the action of two liquid ropes. When the first mouth of the bottle is placed facing downward, the heavy ball blocks the first mouth of the bottle under its own gravity to prevent liquid leakage; when the first mouth of the bottle is turned upwards under the action of the liquid taking rope, the heavy ball falls onto the bottom of the bottle, such that an external liquid can flow into the liquid taking device, which has a good practical utility.

A system for forming a cavity in a backfill mixture comprising granular material and water positioned in an at least partially excavated stope. The system includes a base and a drainage tube assembly in an extended condition thereof. The drainage tube assembly extends between a lower end secured to the base and an upper end positioned above an upper surface of the backfill mixture. The extended drainage tube assembly includes a tube portion thereof with a permeable material and defining the cavity therein into which the water from the backfill mixture is drainable, through the permeable material. The system also includes a drainage pipe, for permitting the water that has drained into the cavity of the extended drainage tube assembly to exit the stope.

A system for forming a cavity in a backfill mixture comprising granular material and water positioned in an at least partially excavated stope. The system includes a base and a drainage tube assembly in an extended condition thereof. The drainage tube assembly extends between a lower end secured to the base and an upper end positioned above an upper surface of the backfill mixture. The extended drainage tube assembly includes a tube portion thereof with a permeable material and defining the cavity therein into which the water from the backfill mixture is drainable, through the permeable material. The system also includes a drainage pipe, for permitting the water that has drained into the cavity of the extended drainage tube assembly to exit the stope.

An extraction well system is disclosed that allows for isolation of electrical cables from underground mine atmosphere. The extraction well system provides for a well casing that extends downwardly proximate to an existing mine cavity and an extension casing that extends downwardly below the mine roof. In one embodiment the extension casing is external to the well casing and is attached to the well casing mechanically such as with a dual thread reducer. The extension runs from above the mine roof to below the mine floor and is perforated in the area of the mine cavity to allow liquid to drain into the bottom of the extension well. In a second embodiment, the extension casing is interior to the well casing and is attached for example by an internal liner hanger. In this embodiment, the extension casing runs from above the mine roof to below the desired minimum liquid level and it is the well casing that extends downwardly in the extension well and which is perforated to allow liquids to flow into the well.

An extraction well system is disclosed that allows for isolation of electrical cables from underground mine atmosphere. The extraction well system provides for a well casing that extends downwardly proximate to an existing mine cavity and an extension casing that extends downwardly below the mine roof. In one embodiment the extension casing is external to the well casing and is attached to the well casing mechanically such as with a dual thread reducer. The extension runs from above the mine roof to below the mine floor and is perforated in the area of the mine cavity to allow liquid to drain into the bottom of the extension well. In a second embodiment, the extension casing is interior to the well casing and is attached for example by an internal liner hanger. In this embodiment, the extension casing runs from above the mine roof to below the desired minimum liquid level and it is the well casing that extends downwardly in the extension well and which is perforated to allow liquids to flow into the well.

An assembly that fits within a ventilation shaft open to atmosphere and leading from underground ventilation ducts such as to subways prevents surface waters from flooding the underground ducts while maintaining the ventilation. The assembly fits in the ventilation shaft and houses a buoyant float in a chamber surrounding a passageway in fluid communication with the ventilation shaft. A grate covers the passageway. An outside wall of the chamber adjacent the ventilation shaft is open at top to atmosphere and allows flooding water into the chamber, buoying the float upward in the chamber, elevating the passageway above the flooding water. The chamber suitably has means for drainage and admission of flush water to flush flood water debris from the chamber through the drainage.