Mine environmental geological problems in Qinling-Yunnan-Guizhou Zhongshan Plateau geological environment area

This area includes Panzhihua-Xichang area in Sichuan, central Yunnan, eastern Yunnan, western Guizhou and eastern Guizhou, with developed karst landforms. The tectonic position belongs to the western margin of Yangtze platform and the northern part of South China tectonic belt. This area has good metallogenic conditions, high working level, rich mineral resources and high degree of development. About 60% of mining enterprises and 65% of mine environmental geological problems in Southwest China are distributed in this area. The minerals developed include iron, copper, lead and zinc, manganese, aluminum, tin, gold, nickel, phosphorus, coal, rare earth and a large number of non-metallic minerals. The environmental geological problems of mines mainly include mercury pollution, arsenic pollution, fluorine pollution, sulfur pollution, phosphorus pollution, landslide, debris flow, collapse, mine water inrush, occupation and destruction of land resources and landscape resources, soil erosion and other environmental geological problems, which are now described in five blocks.

(1) Environmental geological disasters such as landslides, mudslides, collapses and ground fissures in central Yunnan.

This area, including Kunming, Yuxi and Chuxiong, is the most economically developed area in Yunnan Province. The region is rich in mineral resources, and now mainly mines minerals such as phosphorus, copper, iron, coal and construction sand, and there are many medium-sized and above mining enterprises. Mine geological disasters occurred in the area 159, with 37 deaths1person, which is a serious geological disaster area (Table 3-23). The main types of disasters are landslides, mudslides, collapses and ground fissures. The mining of phosphate rock, copper mine, building sandstone and Yuxi copper mine in Kunming has great influence on the geological environment. Because phosphate rock is mostly distributed along the coast of Dianchi Lake, it has a great influence on the water quality of Dianchi Lake. The problem of collapse and landslide caused by sand mining and quarrying around Kunming is more prominent, such as the collapse of Xishan quarry and the landslide of Sunjiaqing sand mining field, which all caused deaths. The copper mining in Dongchuan District of Kunming has a long history, which has a great influence on the geological environment. Debris flow, landslide and other geological disasters occur frequently, which is one of the most serious geological disasters in Yunnan Province. Yimen Mining Bureau in Yuxi City, due to improper mining and harsh natural conditions, geological disasters such as mudslides, collapses, landslides and dry springs have been seriously damaged. For example, Fengshan Mine and Shishan Mine collapsed and accumulated in Caiyuan River, filling the riverbed for 20 ~ 40m, causing tens of millions of economic losses.

Table 3-23 Distribution Statistics of Mine Geological Hazards in Central Yunnan

(2) Environmental geological disasters such as mine landslide, ground collapse, ground collapse, ground fissure and mine water inrush in eastern Yunnan.

The district includes Zhaotong City, Qujing City, Wenshan Prefecture and Honghe Prefecture. Among them, Zhaotong City and Qujing City are located in the north with a long history of mine development. The main minerals mined are coal, copper, lead and zinc, which are the main coal-producing areas in Yunnan Province. Due to historical mining without considering environmental protection, coupled with local adverse geological factors, geological disasters caused by coal mining are serious, and coal mining damage is prominent. A total of mine geological disasters 19 1 occurred in this area, and 83 people died due to the disasters (table 3-24). The main types of disasters are landslide, ground collapse, ground collapse, ground fissure and mine water inrush.

Wenshan Prefecture and Honghe Prefecture, located in the south of the area, are tin-based nonferrous metal bases in Yunnan Province. Tin mining has a long history, and it is the region with the largest number of large and medium-sized mines and developed mining industry in Yunnan Province. The main mineral mined is tin, in addition to copper, manganese, lead, coal and limestone. Geological disasters and environmental pollution caused by mine development in this area are very prominent. There are 193 mine geological disasters in the area, and 674 people died due to the disasters, which is the most serious geological disaster area. The main types of disasters are landslides, land subsidence, ground fissures and mudslides. 1On September 26th, 962, the dam of Huogudu tailings pond in COVID-19 Mining and Dressing Plant in Gejiu broke, which triggered a mudslide and killed 17 1 person; The "5.3 1" and "6.3" landslides in Laojinshan occurred in 1996, and 372 people were killed or missing in a few days (Table 3-24), which was the worst disaster. There are a lot of tailings and ore washing water in this area, with an annual output of 1505.97× 104t and an annual output of 399 1.45× 104t. In history, tin mine sewage was discharged into Gejiu Lake, causing thousands of arsenic poisoning, and the tailings pond collapsed and polluted groundwater.

Table 3-24 Statistics of Environmental Geological Problems of Mines in East Yunnan

(3) Environmental geological problems such as ground subsidence, ground fissures, landslides, collapses, environmental pollution, fluoride poisoning, arsenic poisoning, etc.

Guizhou province is roughly bounded by the north-south Guizhou-Chongqing railway, which is divided into two parts: Qianxi and Qiandong.

Xishui and Liupanshui areas in the north of western Guizhou are mainly coal-producing, with a total of 2394 coal mines. The terrain in the area is high and steep, the coal seam is generally shallow, the mining method is underground mining, the mined-out area is large, the coal gangue piles up like a mountain, and the coal output is high, with an annual coal output of 7424× 104t. The main mine environmental geological problems are ground subsidence, ground subsidence, ground fissures, landslide collapse in goaf, mine water inrush, occupation, land resource destruction and environmental pollution. According to incomplete statistics, the annual output of mine wastewater is 71884/kloc-0 /×104m3, the annual discharge is 625559× 104m3, and the annual treatment capacity is12197/kloc-. The annual treatment capacity of mine waste residue is 12239× 104m3, the annual discharge capacity is 9069× 104t, the annual treatment capacity is 6534× 104t, and the annual recovery capacity is 474/kloc-0 /×/kloc-0. The energy mine covers an area of 28606hm2, including: mine field 17446 hm2, dump (including coal gangue) 2 193.4hm2, tailings pond 1084hm2 and tailings pond 7882.1hm2; For land subsidence. There were 432 mine geological disasters with 239 casualties; There are 285 mines that destroy the groundwater balance system and cause water pollution.

There are more than 500 mining enterprises in Qingzhen, Xingyi, Qinglong, Zhenfeng and Danxiang in central and southern Guizhou, mainly bauxite, gold, lead-zinc mine and antimony mine. The environmental geological problems caused by mines are mainly geological disasters such as landslides and mudslides, environmental pollution and the occupation and destruction of land resources. Covering an area of about 800hm2, the annual discharge of waste residue is 430× 104t and wastewater is 220× 104m3.

(4) Environmental geological problems such as mine water resources destruction, environmental pollution and mercury poisoning in eastern Guizhou.

East Guizhou includes Kaiyang, Zunyi, Weng 'an, Danzhai, Tongren, Wanshan, Songtao and Wuchuan. There are about 2000 manganese, phosphate, mercury and various nonmetallic minerals. The main environmental geological problems in mines include mercury pollution, phosphorus pollution, geological disasters of landslides and mudslides, destruction of groundwater balance system, occupation and destruction of land resources, etc. According to incomplete statistics, the mine discharges 400× 104m3 of mine wastewater, 245.64×104t of mine waste, occupies and destroys 2 126.75hm2 of land resources, and 25 mine geological disasters occur with 28 deaths.

Mercury poisoning in this area is very serious. At present, there are 46 mercury mines of different scales, about 120 occurrences and 50 mineralized occurrences. Mercury anomalies are mainly distributed in Wanshan mercury mine, Tongren mercury mine, Wuchuan mercury mine and Danzhai mercury mine. The mercury content in mercury ore is 0. 1% ~ 0.5%. Mercury that harms the environment mainly exists in the form of natural mercury and mercury vapor. For example, in Sandu-Danzhai and Wanshan-Tongren mercury mine belts, natural mercury anomalies appear in soil, water and air, and mercury poisoning diseases are prevalent. This area is a typical mercury anomaly area in Guizhou Province. After the mercury mine is put into development, in the process of mining, mineral processing and smelting, the mercury content in the environment increases, which intensifies the mercury pollution, and the incidence often increases greatly. In the past, the environmental protection of mines was not paid enough attention, and the selected slag was not stored and kept in a standardized way, and was directly dumped in the valley without protective facilities. The mercury content in slag is between 0.2% and 0.3%, which is leached and washed by surface water and rainwater, polluting the environment. Especially in the flood season, the waste residue flows into the river and farmland with the flood, polluting the river and farmland. In the process of pyrometallurgy of mercury, mercury-containing waste gas is discharged into the atmosphere to varying degrees, which leads to the increase of mercury content in the atmosphere. In addition, metallic mercury scattered on the ground volatilizes, and mercury-containing gases are emitted to varying degrees. These waste gases are inhaled through the mouth, respiratory tract and skin of human body, causing harm to human body. In some mercury production workshops, the concentration of mercury reaches 0.65mg/m3, which is 64 times the allowable concentration of national health standards.

A few years ago, the relevant units conducted a survey on mercury mine production units and nearby residents, and the sampling rate was 20%. As a result, the number of people with mild mercury poisoning is about 10%, the number of people with moderate mercury poisoning is 1%, and mercury processing and smelting workers account for 32% and 50% respectively. It can be seen that mercury pollution has different degrees of harm to people living in mercury abnormal areas.

(5) Environmental geological problems such as mine landslide and debris flow in Panxi, Sichuan.

Panxi, Sichuan is an important ore concentration area, with famous Panzhihua vanadium-titanium magnetite, Huili Tianbaoshan lead-zinc mine, Huidong Liangzi lead-zinc mine, Mianning Maoniuping rare earth mine, Huili Lala copper mine and scattered small and medium-sized mines. Open-pit mining is the main mining method in large mines. Mine environmental geological problems mainly include landslide, debris flow, ground subsidence geological disasters, groundwater drainage, environmental pollution and occupation, land resources destruction and so on. According to preliminary statistics, the annual output of wastewater in this area is11960×104m3, the cumulative amount of slag is 39,089.3×104t, and the occupied and destroyed land area is 3528.2hm2 There is slope instability in Taihe vanadium-titanium magnetite stope and dump, and there is debris flow hazard in tailings pond. The dump of Lu Gu Iron Mine was destroyed, and a large amount of waste residue was piled up in Yanjinggou, which was a hidden danger of debris flow. The goaf of Baoding Coal Mine in Panzhihua caused a large area of collapse and cracking, which seriously damaged the ecological environment. Coal gangue accumulates in valleys and hillsides, causing geological disasters such as landslides and mudslides and environmental pollution. Panzhihua vanadium-titanium magnetite, mining waste residue accumulated into man-made mountains, leading to geological disasters such as mudslides and landslides in flood season. The tailings pond covers an area of 8km2, and the surface water and groundwater are polluted. There are a large number of copper-lead-zinc mines in Huili and Huidong areas, and many landslides have formed in the stope, which have hidden dangers such as debris flow of waste rock piles, drainage of groundwater, surface collapse and environmental pollution. In particular, the lead-zinc deposits in this area have high cadmium content, which pollutes water, soil and biological chain.