Environmental geological problems of energy mines

There are 6769 mines with energy resources in Southwest China, accounting for 32. 1% of the total number of mines. Among them, Yunnan 1483, Sichuan 1567, Guizhou 2395, Tibet 8, Chongqing 13 16.

Energy minerals mainly refer to coal. It is distributed in western Guizhou, followed by western Chongqing, northeastern Yunnan, Sichuan Basin, southeastern Sichuan and Panzhihua in southwestern Sichuan. Important coal mining enterprises include Shuicheng Coal Mine, Liuzhi Coal Mine, Panxian Coal Mine, Zunyi Coal Mine, Anshun Coal Mine, Tianfu Coal Mine, Yongrong Coal Mine, Songzao Coal Mine, Nantong Coal Mine, Zhongliangshan Coal Mine, Zhaotong Coal Mine, Xuanwei Coal Mine, Fuyuan Coal Mine, Xiaolongtan Coal Mine, Yipinglang Coal Mine, Qujing Coal Mine, Wangguang Coal Mine, Furong Coal Mine and Baoding Coal Mine, and other small coal mining enterprises are scattered all over the place.

Energy mines are mainly mined underground, and the mined-out area is large, which is easy to cause geological disasters such as ground collapse and ground fissures, and at the same time, it is difficult to drain surface water and use water. At the same time, there are a lot of coal gangue accumulation in the process of coal mining, and precipitation leached it to produce a lot of sulfuric acid and other pollution to groundwater and surrounding soil. The sulfur in it will also emit various harmful gases such as H2S, SO2 and CO2 after evaporation or spontaneous combustion of coal gangue, which will seriously pollute the atmosphere. According to preliminary statistics, energy mines in southwest China occupy and destroy the most land area, which is 12 1706.49hm2, accounting for 6 1.2% of the total occupied land area. In the rainstorm season, coal gangue is also easy to cause geological disasters such as landslides and mudslides. Water inrush from energy mines is also very serious. The environmental geological problems of energy mines in southwest China are prominent in Chongqing and Guizhou provinces, followed by Sichuan and Yunnan provinces, and Tibet again. Among the 254 mine geological disasters in Chongqing, there are 230 energy mines, accounting for 90.6% of the total disasters, with direct economic losses of 368 million yuan, accounting for 96.08% of the total losses, and 1 18 deaths, accounting for 90.8% of the total deaths. Among all kinds of mine geological disasters in Chongqing, the biggest loss is the mine water inrush from energy mines. On June 13, 2002 alone, the direct economic loss caused by mine water inrush in Nantong Coal Mine reached 200 million yuan, accounting for 52.2% of the total loss in Chongqing.

(A) geological disasters in energy mines

1. Geological disasters such as ground collapse, settlement and ground fissures in energy mines.

The ground collapse of energy mines is mainly related to goaf. The mining depth of state-owned coal mines such as Songzao Nantong Coal Mine in Chongqing and Liupanshui Coal Mine in Guizhou is mostly below1.50m. The surface of large mined-out areas is seriously subsidence, tensile deformation and collapse, which affects and destroys ground buildings and road facilities, resulting in significant economic losses and casualties.

The ground collapse of Nantong Coal Mine (1) in Songzao County, Chongqing

1) Basic overview. According to the Investigation and Evaluation Report of Mine Geological Environment in Chongqing, there are 30 collapse pits in Songzao and Nantong mining areas, with a distribution area of about 2.5km2, which are mainly distributed in mined-out areas of Songzao and Nantong mining areas and developed in carbonate rock distribution areas.

There are three forms of subsidence surface deformation: subsidence pit, subsidence and cracking.

The plane shapes of subsidence pits in this area are mainly elliptical and quasi-circular, and some of them are long, with sizes ranging from 3 ~ 3 ~ 200 m2. The main shapes are columnar and funnel-shaped, and the inclination of the cylinder (contact surface with surrounding rock, including funnel surface) is mostly between 60 and 80, and some are between 40 and 50. The depth of collapse varies from several meters to tens of meters, generally more than ten meters. For example, the Shuijingwan coal plant in Nantong mining area collapsed, with a maximum diameter of 200m and a maximum collapse depth of 30m, and more than 20 villagers were forced to move. The deep part of the subsidence area is the mined-out area of Yanshitai Coal Mine.

Land subsidence is formed after the subsidence area, which has the characteristics of wide influence range and large distribution area. The settlement form is mostly pot-shaped or dish-shaped, with a drop of several centimeters. Cracks and collapses in the subsidence area are widely distributed and the number is large. For example, Nantong Chemical Plant in Chongqing, the whole plant is located in the subsidence area, and cracks and collapses in its workshops, office buildings, walls and floors can be seen everywhere, resulting in huge losses.

Ground cracking is a concomitant product of collapse and settlement, involving a wider range and more quantities. Its shape is linear, arc or closed, and it is mostly distributed in subsidence areas. The fracture length is 3 ~ 130 m, the fracture width is 1.5 ~ 40 cm, and the fracture surface is steep with an inclination angle of 80 ~ 90, which tends to point to the collapse center. In addition to the Nantong Chemical Plant mentioned above, the Songzao Mining Bureau in this area opened a ground fissure zone near the first slag yard of coal mine, which is also a typical ground fissure caused by collapse.

There are close internal relations among three kinds of mine geological disasters: collapse pit, collapse and crack. The collapse pit and crack occur in the collapse area, while the crack spreads in an arc with the collapse center or collapse pit as the center, and the collapse pit is located in the center of the collapse area.

2) Harmfulness. The coal mine subsidence area in Chongqing mainly involves Wansheng District, Qijiang County and Nanchuan City, with 23 147 households and 60,268 people affected, and the living area is 1368 139m2. Subsidence affects 32 schools, with an area of12411m2; Impact 10 hospital, with an area of 32,652 ㎡; ; Road damage 149 438+03 km; 487.02km of water supply pipeline, 342 pools and reservoirs and 16 pump houses were destroyed.

3) Cause analysis. ① Ground collapse caused by groundwater discharge. There are karst caves or dissolution cracks in the soluble rock area of the mine. In the process of groundwater drainage, the water level is constantly decreasing and the hydrodynamic conditions are gradually changing, thus reducing the floating support of groundwater to the overlying soil, increasing the hydraulic gradient, accelerating the water flow speed and strengthening the water erosion. In the early stage of precipitation, cave fillers were taken away under the action of groundwater erosion and transportation, which expanded the water flow channel. Then the overlying soil collapses and loses under the action of undercurrent and erosion, forming arch collapse and hidden soil holes; The soil hole expands continuously, so that when the self-weight pressure of the overlying soil exceeds the ultimate compressive and shear strength of the soil hole, the ground will settle, crack and develop into collapse. (2) Ground collapse caused by goaf destruction. The goaf formed by underground mining is mainly supported by safety pillar. If the design of safety pillar is reasonable, the whole safety pillar system and roadway are stable. If the design size is too small, or the stress in safety pillar exceeds its ultimate bearing capacity due to inevitable accidental factors such as weathering, earthquake and progressive failure in the long-term bearing process, safety pillar will be destroyed first, which will lead to the progressive failure of other safety pillar, and the result will inevitably lead to the destruction of the whole reserved pillar system.

When the progressive destruction of the security pillar system in goaf reaches more than 60%, the roof of goaf will collapse. The collapse range formed by caving is generally larger than the goaf, and the collapse pits formed by mining horizontal coal seams are mostly symmetrical with the goaf, that is, the collapse center is the center of the goaf; However, when mining inclined coal seam, the subsidence pit deviates downward, and the position of subsidence and goaf is asymmetric in longitudinal section. This feature should be paid attention to in safety precautions.

(2) Ground collapse of Liuzhi, Panxian and Shuicheng coal mines in Guizhou.

1) basic characteristics. Ground collapse in mined-out areas of energy mines is a common mine geological disaster in coal resource distribution areas in western Guizhou. There are 55 land subsidence stations in this area, of which 1 station is medium, accounting for 1.82% of the total, and the rest are small, accounting for 98. 18% of the total.

2) Harm and loss. According to the data of 19 coal mines under Panxian, Shuicheng and Liuzhi Coal and Electricity Group (Table 3- 17) (Xu Wen et al., 2006), the ground collapse of 19 coal mine * * * destroyed 28.50km2 of cultivated land and 4.36km2 of forest land, and all kinds of roads were damaged by 4/kloc.

3) Cause analysis of ground collapse in goaf. In the process of underground mining, the surface subsidence of goaf destroyed the original stress balance state of rock mass around goaf. In the process of stress redistribution reaching a new equilibrium state, the mine roof is deformed, sunk, collapsed and moved, and these changes spread to the ground, resulting in ground cracks and ground collapse, mountain collapse, landslide and water depletion, which seriously destroyed the mine land resources.

2. Geological hazards of landslides in energy mines

Landslides in energy mines are often related to improper stacking of coal gangue, such as Lindong Coal Mine in Chongqing and Qianxi Coal Mine. Gravel and pulverized coal pile up to 200m, and the volume is 100× 104m3. After long-term exposure to the sun and rain, the water content increases, the weight increases, and the cohesion and internal friction decrease, which leads to the destruction of the stability of the accumulation body and the formation of landslides. There are more than 30 such landslides in western Guizhou. Another part of the landslide is related to the instability of the foot of the slope, such as the small coal mine in Taiping village, Xuyong area, southern Sichuan, which often forms such landslides. Generally speaking, small and medium-sized ones are the main ones, and large ones are rare.

Table 3- 17 Statistical Table of Mining Subsidence Area of Panxian, Shuicheng and Liuzhi Coal and Electricity Group

Chongqing Nantong Lindong Coal Mine (1) Gangue Mountain Landslide

1) Basic overview. Lintong Coal Mine of Nantong Mining Co., Ltd. is located in Hujiagou Community, Xinhua Village, Wandong Town, Wansheng District, Chongqing, with the geographical coordinates of the center; East longitude106 54', north latitude 28 58', with an altitude of about 3 10m, belonging to the municipal state-owned coal mine. The mine was built in 1958 and put into production in April 1964. Now it has become one of the largest major coking coal mines in Southwest China, and its products are mainly supplied to Chongqing Iron and Steel Group Corporation.

The mine is mainly mined in the Permian Longtan Formation (P2)k 1(6 #), K2(5#) and K3(4#) coal seams between the main structure of Dongjing-the secondary fold of the northwest wing of Longguxi compound anticline-and Mao Yan anticline, with proven reserves of 640 ~- 100. The designed production capacity of this mine is 45× 104t/a, and the approved production capacity in 2004 is 30×104t/a. There are 2,363 employees and 7 124 residents in the mine (Ren et al., 2006).

At present, the mining elevation of this mine is -36m, the mined-out area is 1.86km2, and the gangue is piled up in Lindong gangue hill, 500m southwest of the main shaft, with the center geographic coordinates of X = 3202950 and Y = 36395920. Gangue is transported to gangue hill through transportation alleys and inclined shafts. The gangue hill has been accumulated for 43 years, with an area of nearly 7× 104m2, accumulation elevation of 400~330m, maximum accumulation height difference of 22m (photo 3- 1), and the total amount of accumulated gangue is 100× 104t.

2) Harmfulness. On the afternoon of June 5, 2004, around 13: 55, a landslide occurred in the gangue hill of Lindong Coal Mine, forming a gangue flow. As shown in Figures 3-2 and 3-3, 14 building was destroyed, resulting in 15 deaths, 3 injuries and 6 missing. At about 7: 40 am on June 25th, 2005, 10, the gangue hill of Lindong Coal Mine collapsed again, and a passing primary school girl was buried to death. With the further accumulation of waste rock, the waste rock hill may landslide again or form waste rock flow, threatening the safety of 58 people in nearby 17 households again and affecting the normal use of Hujiagou-Ganjiaping highway. Surface water flows through waste hills to form sewage, which causes serious pollution to downstream farmland and streams.

Figure 3- 1 Gangue Hill of Lintong Coal Mine in Nantong, Chongqing

Figure 3-2 Chongqing Nantong Lindong Gangue Mountain Landslide Site

Fig. 3-3 The landslide soil of Gangue Mountain in Lintong, Nantong, Chongqing has filled the fish pond below the mountain.

3) Cause analysis. ① Natural factors. The two landslides in Lindong gangue hill occurred after continuous rainfall, and rainfall was the main inducing factor for landslide formation. ② Human factors. The gangue pile is unreasonable, exceeding the original design pile, and it is not handled in time after there are potential safety hazards.

(2) Geological hazards of coal mine landslide in Taiping Village, Dongxiang Town, Xuyong, Sichuan Province.

There are many small coal mines in Taiping Village, Zhendong Town, xuyong county, Luzhou City, Sichuan Province. Due to the deformation of the roof slope of the goaf, a landslide occurred at 1999 at 4: 00pm on July 6th (Figure 3-4), and the landslide volume was 53x104m3. Four people were killed, three were injured, seven villagers' houses were completely buried and six were destroyed (Yonggui Li et al., 2006). Before the landslide, the ground has certain deformation characteristics, and the city's geological environment monitoring station found danger. Publicize and mobilize villagers to resist disasters and strengthen monitoring. Therefore, before the landslide, most people took evasive measures to reduce casualties.

Figure 3-4 7. 16 landslide profile of Taicun Mine, Zhendong Town, xuyong county, Sichuan.

(According to Yonggui Li, 2006)

1-mudstone; 2- Pyrite mudstone; 3- Sandy mudstone; 4— argillaceous siltstone; 5— Siltstone; 6- limestone; 7— Oolitic limestone; 8- Biolimestone; 9- landslide sediments; 10 —— Member 2 of Feixianguan Formation of Lower Triassic; Lower Triassic Feixianguan Formation 1 1- 1 section; 12- Upper Permian Changxing Formation; 13— Upper Permian Leping Fm; 14- Lower Permian Maokou Formation; 15- upper coal seam code; 16- lower coal seam code; 17- original line; 18 —— ground line after landslide sliding; 19-Inference line of landslide sliding

3. Geological hazards of debris flow in energy mines

The formation of debris flow in energy mines is often related to a large number of coal gangue piles, combined with topography and heavy rain, resulting in debris flow geological disasters. It happens from time to time in Chongqing, Sichuan and Guizhou. Debris flow disaster in Tiangongmiao coal mine area of Chengdu is more prominent;

(1) Debris Flow Danger

1 September 1998 17 at about 3: 00 am, affected by heavy rain, mudslides occurred in the mining areas of Yanggou, Xiaogou, Xiaolongxi and Liziping in Tiangong Miao Town, 20 kilometers west of Dayi County, causing roads and bridges to be washed away, traffic and power supply to be interrupted, 10 houses to be destroyed, and a large number of mechanical and electrical equipment and other materials in the mining area to be missing. See Table 3-65,438+08 for details of debris flow losses in gullies.

(2) Formation conditions

The formation of debris flow is not only related to heavy rain, but also closely related to topography, landforms and solid sources.

1) landform conditions. Yanggou, located in the west of Tiangong Temple Town, is a perennial flowing valley. The valley in Tian Yang mining area is 20 meters wide and gradually narrows to several meters in the direction of gully source. The elevation of gully source is 1580m, the elevation of gully mouth is 760m, the total length of open ditch is about 6km, and the longitudinal slope of riverbed drops 136.7%. A gully developed near Zhonggang (Yanggou Mine), with a length of 1.35km and a longitudinal slope of 2 14.8%, causing casualties mainly in this gully section. The longitudinal slope of gully bed in China-Hong Kong section decreased by 6.77%. Debris flow is formed in the section from China-Hong Kong to Gouyuan, and the bridge section from China-Hong Kong to Hekou is a circulation area. The ravine suddenly widened and the running water slowed down. Debris flow carries boulders to deposit here, forming an accumulation area, and the boulders are arranged to a certain extent. The sediments are mainly gray lithic sandstone and breccia, the particle size is generally greater than 30cm, the maximum is 1.2m, the width is over 30m, and the length is about 60 m. The vegetation on the valley slopes on both sides of the valley is good, with a slope of 35 ~ 50. There are state-owned Yongjiang Coal Mine Yang Da, Yanggou Coal Mine and local joint mines in Yanggou, and there are many small coal mines distributed here.

Table 3- 18 Debris Flow Disaster in Tiangong Temple Coal Mine, Chengdu

Xiaogou is located 3km northwest of Tiangong Miao Town, with a length of about 1.5km and an elevation of 870m at the mouth of the gully. The total drop from the ditch source to the ditch mouth is 430m, and the longitudinal slope at the bottom of the ditch drops by 28.67%. Qixing Mine is located in a small ditch with many buildings near the mouth of the ditch. The road passes through the mouth of the ditch, and a culvert with a width of 3.8m and a height of 4.0m is built under the ditch, which is a perennial running ditch with a valley nearby.

Xiaolongxi is located at 1.5km northwest of Tiangong Temple Town. The total length of gully is about 3km, the elevation of gully mouth is 790m, the total drop from gully source to gully mouth is 430m, the longitudinal slope of gully bed is 14.33%, and the gully is narrow and close to the estuary. The vegetation on the hillside is good, with a slope of 40 ~ 50.

The debris flow gully in Liziping Mine is a gully, with a main gully length of 100 m, a gully depth of about 1.5m and a gully width of about1.0 m. There are two branches at the source of the gully, and there is running water from time to time. The slope of the gully bed is 12, and a large number of coal gangue from small coal mines are piled up at the source and at the edge of the gully. There are many buildings at the mouth and side of the ditch, and the ditch water passes through the culvert of the ditch.

2) solid source. The stratum where the debris flow is located is mainly Triassic Xujiahe Formation, with gray debris sandstone, sandy shale and coal seam. The strata are alternately soft and hard, located in the core of anticline, with associated faults. Although the vegetation on the valley slope is good, the ground subsidence and slope deposits are widely distributed on the valley slope, which leads to the emergence of clastic sandstone in the debris flow deposits in the valley mouth. In addition, local township enterprises have developed rapidly in the past decade. In addition to local coal mines, there are many small coal mines in Tiangong Miao coal mine area, and coal gangue is piled up at will, which provides an important material source for the occurrence of debris flow. The solid matter of debris flow in Liziping Mine is mostly coal gangue. There are two small debris flows formed by gullies on the valley slope on the left bank of Yanggou, and their sources are mainly coal gangue. In the middle of the ditch, in the 72 1 coal mine opposite to the local mine, the volume of gangue accumulation is about 2500m3. Due to the erosion of the bank foot, coal gangue accumulation and slope deposits slide down the slope to form debris flow.

To sum up, the formation of debris flow is closely related to natural factors and human factors (disorderly stacking of mining waste residue).

4. Geological disasters of energy mine collapse

The geological disasters of energy mine collapse in southwest China are sudden, difficult to prevent and harmful. Generally, mining in unfavorable geological environment is easy to cause collapse geological disasters. Mainly distributed in western Chongqing, southern Sichuan and western Guizhou.

(1) Geological disaster of coal mine collapse in western Guizhou

In the coal-producing area in western Guizhou, the terrain is cut strongly, the relative height difference is generally 300 ~ 500 m, and the cutting along the river valley can reach 700 ~ 1000 m, especially in some canyons, where the rock walls are steep, which makes the formation of collapse have favorable conditions. But this steep hillside is generally hard rock in the upper part of the slope and soft rock in the lower part. Coal is generally produced in the lower soft rock. Mining further destroys the stability of the mountain, and the overlying rock mass loses its support, leading to unloading and the collapse of the block falling along its vertical direction.

1) Zuojiaying Village, Zongling Town, Nayong County, Guizhou Province collapsed. On February 3, 2004, 65438+ suffered a large-scale collapse geological disaster, 38 people died, 6 people were missing and 13 people were injured. The collapse point is located on the steep cliff behind Yanjiao Formation, with the coordinates of east longitude 105 14' 09 ",north latitude 26 42' 50" and altitude 2 120m. After the collapse, it is found that there are still three obviously dangerous rock masses on the steep cliff around the collapse point, with a total scale of over 30,000 m3, which may lead to another collapse. Under the influence of heavy rainfall and other factors, the slope toe accumulation body is prone to landslide and debris flow disasters, or collapses again above the steep cliff, which will directly threaten the life and property safety of 54 households with 280 people in Xiayanjiao Formation, 59 households with 200 people in Xinfangzi Formation, Sun Xiao Coal Mine and Zuojiaying Coal Mine.

2) At about 2 1 20 on July 7th, 2006, Wanjin No.2 Mine, Fudong Village, Yuan Xian Town, Xishui County, Guizhou Province, suffered a mountain collapse with a collapse volume of about 5000m3, resulting in 2 deaths, 8 missing, 2 injured and 2 buildings destroyed. When the rock mass is in an unstable natural state, coal mining activities induce the formation of collapse. The collapse body is located in the steep bank area formed by river valley scouring, with a height of more than 40 m, and the lower part is a weak basement (coal-producing) composed of shale, on which rock joints and cracks are developed and the rocks are massive. The movement of groundwater along the fracture strengthens the dissolution and weathering, coal mining blasting activities and the vibration of heavy trucks carrying coal, which leads to the instability and collapse of rock mass.

3) On May 29th, 20065438 15: 20, rock mass collapsed in Groups 3 and 4 of Muzan Village, Wuxiong Township, Xingyi City, Guizhou Province. The collapse accumulation reached 90× 104m3, flooding 6 households and 7 residential buildings and 2 Dongfeng vehicles. Farmland was destroyed nearly 13.33hm2, and 10 people died, 2 people were seriously injured and 3 people were slightly injured. The steep cliff in the collapse section is more than 200 m high, and there are many coal mines under the reverse slope at the elevation of1720 ~1780 m. The mining time is long, the mining depth extends to more than 1000 m, and the goaf is large. The roof has collapsed, coal mining and blasting have destroyed the strength and integrity of rock mass, resulting in the instability of soft foundation on steep cliffs, and the instability of soft foundation under the action of gravity and rainstorm.

(2) Geological disaster of Jiguanling coal mine collapse in Chongqing.

1) Basic overview. Jiguanling collapse site is located in Xingshun Township, Wulong County, on the steep slope on the left bank of Wujiang River. The landform in this area belongs to low mountain landform with structural erosion, and the landform is a broken slope with steep downward and gentle upward, with a slope angle of 57 in the lower part and 40 ~ 85 in the upper part. Wujiang River passes through structures and strata, forming a deep V-shaped canyon with a relative height difference of about 300 meters ... The exposed stratum in this area is Paleozoic Permian, and the lower part is Longtan Formation (P2l) dark gray shale, granular sandstone, calcareous shale and gray shale with thin coal seam. The upper part is dark gray, gray-white and blue-gray limestone of Changxing Formation (P2c), which contains flint nodules and locally contains siliceous layers. The stratum occurrence is 3 16 ∠ 72. This area has a solid structure and many stratigraphic folds. The bedrock is exposed, the vegetation is less, and the Quaternary eluvial layer is small and scattered. Xinglong coal mine, a former township enterprise, is located in the middle of the slope.

The Jiguanling collapse occurred on1April 30th, 994, with a volume of about 400× 104m3, as shown in photo 3-4. A large number of rockfalls accumulate on the slope, and a small amount enter Wujiang River to form rockfall dam, resulting in a water level drop of nearly 10m and a surge height of 1 ~ 5m. After the rainstorm on July 4, most of the rockfill bodies on the slope collapsed, and some of them entered the river to form the second rockfill dam (Ren et al., 2006).

2) Cause analysis. The collapse was mainly caused by blind mining in Jiguanling anticline with complex geological conditions in Xinglong Coal Mine, a former township enterprise, and rainfall was also one of the inducing factors.

5. Geological disasters of water inrush in energy mines.

Figure 3-4 Panorama of Jiguanling Collapse in Chongqing

Mine water inrush in southwest China 12 1 time, mainly in energy mines. Because the ore body is located below the groundwater level, it is caused by the deformation and caving of the roof aquiclude in the process of mining or mining, or the old adit with accumulated water in the original mining, or located near the river, affected by the fault zone, poor support and the deformation and caving of the roof aquiclude. The main harm of mine water inrush is flooding the well, affecting the production in the mining area, threatening the safety of underground personnel, and sometimes causing the surface river to stop flowing. The geological disasters of water inrush from energy mines in this area are more prominent.

(1) Geological disaster of water inrush in Chongqing coal mine

At 8: 30 on September/KOOC-0/0, 2003, a water inrush accident occurred at 320m in the heading face of Nanda Lane at the +960 m of Simen No.2 well in Yongdong Town, He Chuan Coal Mine, Xiushan Tujia and Miao Autonomous County, Chongqing, causing/KOOC-0/8 deaths and a direct economic loss of 856,000 yuan.

On June 13, 2004, a water seepage accident occurred in Nantong Mine of Nantong Mining Bureau, and the underground water inflow was nearly 500× 104m3. Nantong mine, Yutianbao mine and Lindong mine were flooded one after another, causing three deaths and direct losses of nearly 200 million yuan. 20,000 employees receive basic living expenses and 40,000 family members receive social assistance, with a designed production capacity of 60× 65433.

(2) Geological disasters of water inrush from energy mines in Guizhou.

From September, 2004 to June, 2005, 5438+ 10, in more than four months, three large mine water inrush accidents occurred continuously in Guizhou Province: on September 5, 2004, a mine water inrush accident occurred in Liuhe Coal Mine, Magu Town, Hezhang County, causing 10 deaths; In June 5438+February 65438+February 2004, a water inrush accident occurred in Tianchi Coal Mine, Xujiaba Town, Sinan County, killing 36 people. June 65438+1October 65438+June 2005, a mine water inrush accident occurred in Lianxing Coal Mine, Dejiang County, causing 7 deaths. These mine geological disasters are all related to unreasonable mining.

(b) Environmental pollution from energy mines

The pollution of energy mines in southwest China is mainly manifested in water pollution and air pollution.

1. Water pollution in energy mines

The water pollution of Gangzishan coal mine water and leaching water is particularly prominent. The pollutants in wastewater mainly include suspended solids, petroleum, sulfides, oxides, volatiles, hexavalent chromium, arsenic, lead, mercury and cadmium. The more serious mines are Nantong Coal Mine in Chongqing, Panzhihua Coal Mine in southern Sichuan and Furong Coal Mine.

(1) Coal Mine Water Pollution in Chongqing

The power plant of Chongqing Nantong Mining Bureau and the coking plant of Nanping Coal Mine in Nanchuan are seriously polluted. There are 1 1 rivers polluted in this area. The polluted river water repeatedly pollutes the groundwater when recharging it. According to groundwater monitoring data, as many as 8 projects in karst water monitoring points in Nantong area exceeded the standard. Among them, the total hardness exceeded 66.7%, the total salinity exceeded 33.3%, the total iron exceeded 100%, the fluorine exceeded 66.7%, the manganese exceeded 100%, the sulfate exceeded 66.7%, the total number of bacteria exceeded 100%, and the coliform exceeded/kloc-.

The coal washing wastewater from Wuxing Coal Washing Plant in Rongchang County, Chongqing has a high concentration of suspended solids, which contains a lot of stone powder and pulverized coal. Without treatment, tailings are directly discharged into the first tributary of Laixi River, which seriously pollutes Laixi River. As a result, the domestic and production water of more than 65,438+0,000 people in Gaochi Village was polluted, which seriously affected the health of local villagers, and the incidence of abdominal distension and liver cancer was much higher than that in other places.

(2) The landscape pollution of Panzhihua Coal Industry Group Company.

Panzhihua Coal Industry Group Co., Ltd. includes Ding Dabao, Xiaobaiding, Taiping, Huashan coal mines and clean coal plants (coal washing plants), forming a coal mining and coal washing joint enterprise distributed on both sides of Jinsha River. The coal extracted from the mine is transported to the coal washing plant by cable car, the washed coal from the coal washing plant is transported to the coking coal plant of Panzhihua Iron and Steel Co., Ltd. by train, and the waste residue is transported to the gangue pile in Nan 'an mining area by cable car. There is a sewage treatment plant by the river. The annual output of the four coal mines of this group company is 2238.07× 104m3, the annual treatment capacity is 2 185.88× 104m3, and the annual recovery capacity is 1945.78× 104m3, with a recovery rate of 86.9%. The clean coal plant (coal preparation plant) is an advanced enterprise of national environmental protection, with the circulating water (closed circuit) reaching Grade I and no production wastewater discharged from the plant. However, dark wastewater still flows into the Jinsha River in the mining area. According to the sampling analysis, the water quality is SO 4·HCO 3mg·Ca type, and the total amount of soluble solids is as high as 1.077.5 g/L, which is closely related to mine drainage, especially the drainage of small individual mines. In addition, after the Mosuo River passes through Taiping and Huashan mining areas, the chemical components such as NO2, total hardness, total soluble solids, oxygen consumption and Mn in the water have exceeded the standard, and the content has increased by 0.75 times, reaching11times.

(3) Water pollution in Sichuan Furong coal mining area

The annual output of mine water in Furong coal mining area is about 1500× 104t, of which the annual output of the fourth state-owned mine is 922.57× 104t, and the annual output of private small mines is 577.43× 104t. State-owned mines treat 554× 104t of pit water every year, accounting for 60% of the annual pit water. The annual profit consumption of mine water in private mines is about 9.3× 104t, accounting for 1.7% of the annual mine water output.

The field investigation and water sample analysis of Sichuan Geological Environment Monitoring Station show that although three state-owned mines, namely Furong Coal Mine, Bai Jiao Coal Mine and Cunninghamia lanceolata Coal Mine, have mine water circulation treatment systems, there are many small private mines around them that have not been treated completely, and the content of sulfate radical (SO2-4) in the water still exceeds the maximum allowable discharge standard of 600 mg/L.. Because the mine water in Hongwei Coal Mine of Furong Mining Bureau is groundwater, it can meet the discharge standard after partial treatment and can be used for agricultural irrigation. Other private small mines are untreated, so the water quality of sulfate radical (SO2-4) mostly exceeds the maximum allowable discharge standard of 600mg/L, and the content of calcium ion (Ca2+) in water also exceeds the maximum allowable discharge standard of 200 mg/L. What's more, for example, sulfate radical (SO2-4) and calcium ion (Ca2+) in mine water discharged from Furong Mountain and Dawan Coal Mine in Gao County. Moreover, the content of magnesium ion (Mg2+) in the water also exceeds the maximum allowable discharge standard, forming acidic water with a pH value of 3.6 ~ 5.2 and a total hardness of 223. 1 ~ 393. 1 mg/L (calculated by CaCO3), which causes serious pollution to the surface water (photo 3-5) (Yonggui Li et al., 2008).

Figure 3-5 Abnormal Discharge Point of Wastewater in Sichuan Furong Coal Mine

(4) Landscape pollution of high-sulfur coal mines in western Guizhou.

Water containing ferrous sulfate and sulfuric acid is widely distributed in high-sulfur coal mines in zhijin county, western Guizhou. The locals call this kind of water "rusty water". Zhijin River, which flows through zhijin county, has been polluted by "rusty water", and the area of paddy fields with "rusty water" in the county accounts for 10.5%, accounting for 42.7% of low-yield paddy fields. With the development of private coal mines, the area of rust water pollution is still expanding, and many fertile fields have greatly reduced production or even lost grain. When the pH value is less than 4.5, rice seedlings will get sick, and when the pH value is less than 3.5, rice seedlings will die. When the acidity of coal mine drainage in Fenghuang area of zhijin county is the lowest, the pH value is less than 2.5, and the pH value of thousands of meters river polluted by it is less than 4.5 (Shine Wong, 2004), which seriously harms the farmland irrigated by this river. Rust water also contains heavy metals, which can enter the food chain and endanger human health.

2. Air pollution in energy mines

Air pollution in energy mines is also quite prominent, which has caused fluorosis and arsenic poisoning, endangering human health.

The places with serious air pollution are mainly in western Guizhou, such as Laowuji Mine of Panjiang Coal and Electricity Group and Wangjiazhai Mine of Shuikuang Group, which all experienced spontaneous combustion in 10, and produced a large number of toxic and harmful gases such as SO2, H2S, CO2 and F; Thousands of coal coking plants in Liupanshui city produce a lot of toxic and harmful gases, causing serious air pollution.

Coal seams in southwest Guizhou contain arsenic and fluorine. When the coal mined in the mine is burned, arsenic and fluorine enter the air, which pollutes the environment and causes human arsenic poisoning and fluorine poisoning. The situation is quite grim. According to the data of Guizhou CDC, there are 640,000 patients with dental fluorosis and 640,000 patients with skeletal fluorosis in Guizhou. Taking the county as a unit, the population of fluorosis is190,000, accounting for about half of the population in Guizhou. According to the investigation of Guiyang Institute of Geochemistry, the fluorine content in coal is 598mg/kg, and that in soil is 903mg/kg. The fluorine content in corn, pepper and other crops baked with coal exceeds the national standard by dozens or even hundreds of times, and the fluorine pollution is quite serious.

Arsenic in the air can enter human body through skin, respiratory tract and digestive tract. The arsenic content in the coal mined in the small coal mine in Jiaole Township, zhijin county City, Guizhou Province is quite high, and heating and drying the grain in the open-pit furnace makes people poisoned. At least 3000 patients with chronic arsenic poisoning have been diagnosed since 1976.

Fluorosis and arsenic poisoning are not only medical problems, but also economic and social problems. In 2006, the central government allocated 24 million yuan and 654.38+200,000 yuan respectively for the purchase of stoves to treat endemic diseases in Guizhou.

On February 23rd, 2003, 65438, a blowout occurred in a natural gas mine in Kaixian County, Chongqing, which polluted dozens of square kilometers with a large amount of hydrogen sulfide gas, causing dozens of deaths and direct economic losses of 1 100 million yuan.

(c) The occupation and destruction of land resources by energy mines

In southwest China, energy mines occupy and destroy the most land area, which is 12 1706.49hm2, accounting for 6 1.2% of the total land area of various mines. Among them, Sichuan energy mine occupies the largest area, accounting for 6825 1.00hm2, accounting for 56. 1% of the total area of energy mines in southwest China. Followed by Guizhou covers an area of 28606hm2, Yunnan 15908.66hm2, Chongqing 7697.7hm2, Tibet 1245.5438+03hm2.

The energy mines in Southwest China are mainly distributed in Sichuan Basin and its surrounding mountainous areas, western Guizhou, western Chongqing and northeastern Yunnan, mainly in coal mines and underground mining. The stope covers a relatively small area, but the solid waste and ground subsidence area cover a large area.

Baoding Coal Mine in Panzhihua, Sichuan, including four state-owned large and medium-sized coal mines and dozens of private coal mines, covers an area of 80km2.

Guizhou province is rich in coal resources, and large-scale development began in the 1960s. Up to now, the discharged coal gangue has piled up like a mountain. At present, there are more than 30 large-scale coal gangue hills in Liuzhi Special Zone, Zhongshan District, Shuicheng County and Panxian Special Zone of Liupanshui City, with a height of more than 80 meters, the highest of which is more than 200 meters. Now, the accumulated coal gangue has reached 9500× 104t, covering an area of 233.3 1 hm2. For example, Panjiang Coal and Electricity Group has 7 large-scale coal gangue hills, covering an area of 660. Nine large gangue hills belonging to Shuikuang Group cover an area of171.72m2. According to this, the amount of gangue discharged from production mines is 20% of that of coal, and that from coal washing is 25% of that of raw coal. Because of the loose structure and poor stability of coal gangue, it is also prone to landslide and debris flow geological disasters when it encounters continuous heavy rainfall.

Chongqing Zhongliangshan Coal Mine has been put into production for 47 years since 1959, covering an area of 10× 104m2. Among them, coal gangue hill is located in Sanshe, Shiyan Village, Huayan Town, south of the mining area, covering an area of 4.6×104m2; ; The gangue hill is located in the Sixth Community of Huayan Town in the north of the mining area, covering an area of about 5.4× 104m2 (photo 3-6), which affects the development of agricultural economy.

Figure 3-6 North Gangue Hill of Chongqing Zhongliangshan Coal and Electricity Co., Ltd.