1. What is a mine flood?

 

During the construction and production process of mines, surface water and groundwater flow into the mine through various channels. When the water inflow exceeds the normal drainage capacity of the mine, it causes mine floods. Once a mine flood (usually referred to as water seepage) occurs, it not only affects the normal production of the mine, but also sometimes causes casualties, inundates the mine and mining area, and poses a serious threat.

 

2. What are the sources of water inflow in mines?

Mine water sources are divided into surface water and groundwater.

(1) Mine flooding caused by surface water. When there are rivers, lakes, ponds, reservoirs, ditches and other ponding near the mine, as well as seasonal rainwater, when the water level rises sharply and exceeds the elevation of the mine mouth, it flows into the mine, or seeps into the mine from cracks, faults or subsidence areas, causing floods. This water source is called surface water.
(2) Mine flooding caused by groundwater. Groundwater includes aquifer water, karst caves, fault water, and old void water.

3. Warning signs of water seepage accidents in mining workfaces?

(1) The coal seam becomes damp and darkened. The coal seam was originally dry and shiny, but due to the infiltration of water, it became damp and dull. If a layer is dug out and still remains the same, it indicates that there is water accumulation nearby
(2) Sweat hangs on the walls of tunnels or coal walls.. The "sweating" on the top plate is mostly in the shape of pointed water droplets, with a tendency to "drip under pressure"

(3) The top plate is exposed to increased water, especially in the form of falling rain

(4) Sometimes the bottom plate suddenly bursts with water before being permeable

(5) The working face temperature drops, the air cools down, and mist vapor is generated

(6) There is a "squeaking" sound of water coming from coal seams or rock formations

(7) The appearance of dynamic water flow is a sign of being very close to the water source. If the effluent is clean, it indicates that it is still slightly away from the water source and the effluent is turbid, indicating that it is close to the water source
(8) The increase of harmful gases in the working face

(9) Coal walls or tunnels "hang red", the acidity of the water is high, the taste is astringent, and there is a foul egg odor.

 

The flood season is a prone and high incidence period for coal mine water accidents, with a significant increase in atmospheric precipitation. It replenishes surface water bodies, underground aquifers, and unsealed old coal mine voids, which can easily lead to an increase in water pressure and water inflow in coal mines; Continuous heavy rainfall may also cause surface water to flow back into the well from the wellhead, resulting in accidents such as flooding and injuring people. This season is also a high-risk period for poisoning and suffocation in underground mines, as well as slope collapse accidents in open-pit mines. It is a critical period for preventing dam collapse accidents in tailings ponds during the flood season.

 

Technical Measures for Mine Water Safety Prevention and Control

Regularly collect, investigate, and verify the situation of adjacent coal mines and abandoned old kilns, and mark their locations, mining ranges, mining years, water accumulation, etc. on the comparison map above and below the well.

Establish a groundwater dynamic observation system for the main aquifer (section), conduct groundwater dynamic observation and water hazard prediction, and formulate corresponding comprehensive prevention and control measures of "exploration, prevention, blockage, interception, and discharge".

 

We must adhere to the principle of "predicting and forecasting, exploring every excavation, exploring before excavating, and treating before mining" for water exploration and release, and we must stop any doubts. During the excavation process, it is necessary to explore and excavate at the same time to grasp the hydrological conditions of the goaf ahead and above. If water disasters are found, measures should be taken in a timely manner, and excavation should be carried out only after safety is confirmed. The location of the water outlet point should be marked on the comparison map above and below the well or the mining engineering map. The main water outlet points or sections exposed by well tunnels must undergo comprehensive observation and analysis of groundwater dynamics such as water temperature, water quantity, and water quality, as well as the inflow and sand content of loose aquifers, to prevent lagging water inrush.

 

When there are signs of sudden water influx such as redness, sweating, cold air, fog, water splashing, increased water dripping on the roof, pressure on the roof, bulging or cracking of the bottom plate, water seepage, turbid water color, and foul odor found on the mining face or other locations, the operation must be stopped, measures must be taken, and the mine dispatch room must be immediately reported, an alarm should be issued, and all personnel at water threatened locations must be evacuated.

 

Keep the underground and surface drainage ditches unobstructed, clean them up in a timely manner, conduct a comprehensive inspection of mine water prevention and control work before the rainy season every year, establish flood prevention and rescue teams, and reserve sufficient flood prevention and rescue materials.

 

It is necessary to strengthen the investigation of small and old kilns on the ground and mark them in the actual mining engineering drawings, delineate their drainage red lines, and take drainage measures when approaching the drainage water line.

 

It is necessary to first investigate the water collection and leakage situation of the surface water flow system in the mining area and its vicinity, grasp the local annual precipitation and highest flood water level data, and establish drainage, waterproofing, and drainage systems.

 

Buildings within industrial sites must be equipped with flood control ditches or other measures for prevention and drainage.

 

Considering that surface water bodies near the wellhead and in the subsidence area may collapse into the underground, the following regulations should be followed: ① It is strictly prohibited to mine waterproof coal pillars along the coal seam outcrop line. ② Places that are prone to water accumulation should build ditches to drain the accumulated water. When constructing ditches, it is necessary to avoid outcrops, cracks, and water conducting rock layers. Especially in low-lying areas where ditches cannot be built for drainage, they should be filled and compacted to prevent accumulated water from entering the underground The mine water discharged to the ground must be properly treated to avoid re infiltration into the underground The leaking drainage ditch should be promptly sealed, and ground cracks and collapses must be filled. The filling work must have safety measures to prevent personnel from falling into the collapse pit.

 

Key points and procedures for self rescue of mine permeability

Any signs of water seepage should be reported immediately to the dispatch room. If the situation is urgent and water seepage is about to occur, an alarm must be issued immediately, and decisive measures must be taken to prevent water seepage, prevent well flooding, and promptly evacuate all personnel threatened by water damage.

When evacuating, obey orders, do not panic, pay attention to walking towards higher ground, and exit the well along the predetermined disaster avoidance route.

 

The staff located below the permeable point should try their best to hold their breath when encountering strong and high water heads during evacuation. They should use their hands to grab onto pipes and other objects to prevent choking and drowning. They should bravely push through the water head and quickly evacuate to a safe location with the help of tunnel walls and other objects.

 

When the road outside is blocked by water and cannot be evacuated, one should choose the location with the highest terrain, closest to the wellbore or alley, or temporarily avoid the isolated alley on the mountain. The personnel trapped in the isolated alleyway up the mountain should be mentally prepared for prolonged blockage, conserve the use of mining lamps and food, regularly strike metal utensils, and send out distress signals. At the same time, we should promote the spirit of unity and mutual assistance, overcome difficulties together, and firmly believe that our superiors will spare no effort to rescue us, and we can safely escape danger. To endure hunger and lie still, reduce consumption, drink water to prolong life, and wait for rescue and escape.

 

If the water seeps from the old air or kiln, a large amount of toxic gas will also emerge. When evacuating, everyone should quickly wear a self rescue device or cover their mouth and nose with a wet towel to prevent poisoning or suffocation.

 

When passing through the water gate during the evacuation, the last person to evacuate should immediately close the water gate tightly. The water pump driver is absolutely not allowed to leave their work post without receiving the evacuation order from the disaster relief command center.

 

Tailings pond and mine safety precautions

 

1、 Strictly prevent safety risks in underground mines

1. Identify the 'external water'. Accurately identify the surface water flow system and catchment area in the mining area and nearby areas, the catchment situation of rivers and ditches, drainage capacity, and the current situation of water accumulation areas, and improve the waterproof and drainage system.

2. Master the "internal waters". Verify the ponding area, aquifer, karst zone, geological structure, etc. in the mining area, master the hydraulic relationship between the mine and groundwater, surface water and atmospheric rainfall, and the movement law of the mining area water, and analyze the possible risks after rainstorm.

3. Prevent water influx. Standardize the operation, strictly follow the water exploration and drainage design for excavation and mining operations, and regularly clean the silt in the ditches, sedimentation tanks, and water tanks.

4. Timely "drainage". Promote the construction of a dual prevention mechanism for non coal mines, implement flood season prevention measures, strictly implement a 24-hour dedicated monitoring system during the flood season, and ensure the normal operation of lifting, drainage, ventilation and other equipment.

5. Effectively manage water. Highlight the strengthening of monitoring efforts for mines located near rivers, lakes, reservoirs, and mountainous areas that are threatened by disasters such as floods and mountain torrents.

 

2、 Strictly prevent safety risks in tailings ponds

1. To 'block newly created'. It is strictly prohibited to create new tailings ponds, promote the management of tailings pond sales, strictly control the increment, reduce the stock, and ensure that the total amount is only reduced and not increased.

2. To 'control the operation'. Urge tailings pond enterprises to strictly follow the design for tailings discharge and dam construction, achieving "efficient and fast drainage", "less water storage, less water storage, and no water storage".

3. Keep an eye on the closed inventory. Intensify efforts to cancel and upgrade closed tailings ponds, encourage tailings pond enterprises to actively adopt advanced technologies such as tailings recovery, filling goaf, and dry tailings disposal to reduce tailings pond emissions.

4. To 'guarantee the last'. Install a safety online monitoring system, strictly implement 24-hour duty during flood season, assign dedicated personnel to patrol the dam and report accident information, organize joint emergency drills, improve emergency plans and material reserves.

 

3、 Strictly prevent risks in open-pit mines

1. Ensure 'slope stability'. Strictly follow the mining design plan to mine in layers and steps, strictly control the slope angle, slope angle, and final slope angle of the control steps.

2. Ensure smooth communication. Set up step drainage ditches, take appropriate flood control measures, and timely discharge floods.

3. Ensure that 'people evacuate'. In extreme weather such as rainstorm, lightning and typhoon, stope operation shall be stopped and operators shall be evacuated quickly.

 

4、 Strictly prevent safety risks in waste disposal sites

1. "The guarantee facilities must be in place. Set up interception, flood control, and drainage facilities.

Warning signs should be in place. Define the danger zone and set up warning signs.

3. 'Daily management should be in place'. Regularly inspect, promptly repair and identify problems, and take timely measures to prevent landslides.

Emergency rescue must be in place. Clearly define flood prevention safety production.

 

Source: Emergency Management Office, etc., for reference only.