Brief introduction of coal
Coal pollution is mainly composed of carbon, hydrogen, oxygen, nitrogen and sulfur, and there are also very few elements such as phosphorus, fluorine, chlorine and arsenic. Carbon, hydrogen and oxygen are the main organic matter in coal, accounting for more than 95%; The deeper the coalification, the higher the carbon content and the lower the hydrogen and oxygen content. Carbon and hydrogen are the elements that generate heat when coal is burned, and oxygen is the combustion-supporting element. When coal is burned, nitrogen does not generate heat, but is converted into nitrogen oxides and ammonia at high temperature and precipitated in a free state. Sulfur, phosphorus, fluorine, chlorine and arsenic are harmful components in coal, of which sulfur is the most important. When coal is burned, most of the sulfur is oxidized into sulfur dioxide (SO2), which is discharged with flue gas, polluting the atmosphere, endangering the growth of animals and plants and human health, and corroding metal equipment. When high sulfur coal is used in metallurgical coking, it will also affect the quality of coke and steel. Therefore, the content of "sulfur" is one of the important indexes to evaluate coal quality.
The combustible gas produced by the decomposition of organic matter in coal under certain temperature and conditions is called "volatile matter", which is a mixed gas composed of various hydrocarbons, hydrogen, carbon monoxide and other compounds. Volatile is also the main coal quality index, which plays an important reference role in determining the processing and utilization mode and technological conditions of coal. Coal with low coalification degree has more volatile matter. If the combustion conditions are not suitable, the coal with high volatile content will easily produce unburned carbon particles when burning, commonly known as "black smoke"; And produce more pollutants such as carbon monoxide, polycyclic aromatic hydrocarbons and aldehydes, and the thermal efficiency is reduced. Therefore, suitable combustion conditions and equipment should be selected according to the volatile matter of coal.
There are few inorganic substances in coal, mainly water and minerals, and their existence reduces the quality and utilization value of coal. Minerals are the main impurities in coal, such as sulfide, sulfate and carbonate, most of which are harmful components.
Moisture has a great influence on the processing and utilization of coal. When water becomes steam during combustion, it absorbs heat, thus reducing the calorific value of coal. The moisture in coal can be divided into external moisture and internal moisture, and internal moisture is generally used as an index to evaluate coal quality. The lower the degree of coalification, the greater the internal surface area of coal and the higher the moisture content.
"Ash" is the solid residue left after coal is completely burned, and it is an important coal quality index. Ash mainly comes from incombustible minerals in coal. When mineral is burned, it absorbs heat, and a large amount of slag will take away heat, so the higher the ash content, the lower the thermal efficiency of coal combustion; The more ash, the more ash produced by burning coal, and the more fly ash discharged. Generally, the ash content of high quality coal and clean coal is relatively low.
Pollution performance
Coal Pollution 85% of China's coal is directly burned, mainly including thermal power generation, industrial pot (kiln) furnace, civil heating and household stoves. Burning coal with high consumption and low efficiency will release a lot of sulfur dioxide into the air. 2、CO？ And soot, which is the main cause of air pollution in China. ?
(1) Coal mining leads to the destruction of land resources and the deterioration of ecological environment. Due to stripping and dumping of open-pit mining, surface subsidence and cracks in underground mining will destroy land resources and plant resources, affect land cultivation and vegetation growth, change landforms and cause changes in landscape ecology. Mining subsidence caused a large area of flooding or salinization in the eastern plain mining areas of China, which aggravated soil erosion and land desertification in the western mining areas. Coal mining subsidence will also cause landslides or mudslides in mountainous areas and hills, endangering the safety of ground buildings, water bodies and traffic lines. According to the survey, the forest area directly destroyed by mining in China has reached 6,543,800+0,600 hectares, and the grassland area has been destroyed by 263,000 hectares. The total land occupied by China is about 5.86 million ha, and the land destroyed is about 6.5438+0.57 million ha, which is still increasing at the rate of 40,000 ha per year, while the land reclamation rate in mining areas is only 65.438+00%. According to another calculation, for every 1 10,000 tons of coal mined in China, the average land subsidence is 0.2ha；; In the plain mining area with dense villages, about 2000 people need to be relocated for every 6.5438+million tons of coal mined. ?
(2) Coal mining destroys groundwater resources and intensifies water shortage in water-deficient areas. China is a country with low per capita water resources in the world, and the distribution of water resources is extremely unbalanced. Judging from the distribution of coal-bearing areas, coal-rich areas are often water-deficient areas. According to the survey, among the 96 state-owned key mining areas in China, water-deficient mining areas account for 7 1%, of which 40% are seriously short of water. With the increasing intensity and extension speed of coal mining, the groundwater level in the mining area has dropped in a large area, which makes the water supply in water-deficient mining areas more tense, thus affecting the production and life of local residents. On the other hand, due to the destruction of coal measures strata, a large number of groundwater resources leaked into the mine and discharged, and less than 20% of these mine water was purified and utilized, which caused new pollution to the surrounding environment of the mining area. According to statistics, all kinds of wastewater produced by coal mines in China account for about 25% of the total wastewater in China. In 2000, the national coal mine wastewater discharge reached 2.75 billion tons, including 2.3 billion tons of mine water, 350 million tons of industrial wastewater, 50 million tons of coal washing wastewater and 4.5 million tons of other wastewater. ?
(3) Coal mining leads to waste gas emission and harms the atmospheric environment. The waste gas formed by coal mining mainly refers to mine gas and gas released by spontaneous combustion of ground waste hills. Methane is the main component of mine gas and an important greenhouse gas, and its greenhouse effect is 2 1 times that of CO2. According to statistics, China emits 7-9 billion cubic meters of methane every year due to mining? 3. It accounts for about 30% of the total methane emissions in the world. Except for about 5% centralized recovery, the rest are all discharged into the atmosphere. The spontaneous combustion of the ground gangue hill in the mining area releases a lot of toxic and harmful gases such as SO2, CO2 and CO, which seriously pollutes the atmospheric environment and directly harms the health of the surrounding residents. The output of coal gangue is very large, and its emission accounts for about 15% ~ 20% of the output of raw coal in coal mines. According to incomplete statistics, there are more than 1500 gangue hills in China's state-owned coal mines, with a cumulative amount of 3 billion tons over the years and an area of 5,000 hectares. According to 1994 mine environment survey, 464 coal gangue hills in the semi-arid area north of Huaihe River 1072 spontaneously ignited, and the spontaneous combustion rate reached 43.3%. ?
(4) In order to meet the social demand for clean coal, the proportion of raw coal washing in China has increased year by year. 1999 raw coal washing capacity was 3170,000 t, accounting for 30%, of which the proportion of state-owned key coal mines reached 48%. When washing raw coal, a large amount of slime water is also discharged to pollute soil vegetation and water system. According to the survey, China discharges 45 million tons of coal gangue, 40 million tons of coal washing wastewater and 2 million m3 of coal slime every year. ?
(5) In China, the huge spatial difference between coal production and consumption leads to the long-distance coal transportation pattern of "transporting coal from north to south and coal from west to east". The flying coal dust during transportation not only lost a lot of coal, but also polluted the ecological environment around the line. According to statistics, the national railway coal transportation capacity in 1999 was 649 17000 t, with an average transportation distance of 550km；. 600 million tons of coal are transported by road or railway, with an average transportation distance of 80 kilometers. If the dust loss is calculated as 0.5%, the coal dust discharged into the atmosphere due to transportation will reach more than 6 million tons, and the direct economic loss will exceed 600 million yuan. ?
(6) China's long-term coal-based energy consumption structure has not only caused soot-type air pollution with acid rain, sulfur dioxide and soot as the main hazards, but also the main reason why China's pollutant emissions rank second in the world. Statistics show that in 2000, the total emission of SO2 in the national exhaust gas was19.95 million t, including16120,000 t from industrial sources and 3.83 million t from domestic sources. The total amount of smoke and dust emission is11650,000 t, including 9.53 million t for industrial smoke and 21200,000 t for domestic smoke and dust. The acid rain area accounts for about 30% of the land area. Present situation and difficulties of environmental protection and treatment in coal mining areas.
A few days ago, Greenpeace, an international environmental protection organization, and CEDELFT, an independent and authoritative energy agency in the Netherlands, released a global report, The Real Cost of Coal, pointing out that in 2007, global coal use caused losses of at least 360 billion euros (about 3.2 trillion yuan).
Greenpeace called on all countries in the world to pay attention to the environmental consequences caused by coal burning, and immediately reduce and gradually give up the use of coal.
Aneska Markuska, an expert at the Sedford Institute, said: "The annual loss of 360 billion euros is actually a relatively conservative calculation. If effective measures are not taken to actively stop climate change, the resulting losses will rise sharply. " For example, billions of people will face water shortage, food security of hundreds of millions of people will be threatened, and extreme weather will become more frequent.
In addition, coal directly pollutes water and air and causes black lung disease.
Protection and governance
Coal pollution (1) policies and regulations, and increased investment in environmental protection. The state has successively promulgated and revised 13 laws and regulations directly related to environmental protection in coal mining areas, which made the environmental protection and governance in mining areas step into the legal track and accelerated the development of mine environmental protection. According to incomplete statistics, during the Ninth Five-Year Plan period, the coal industry invested 2.86 billion yuan in environmental management, with an average of 570 million yuan per year. ?
(2) Land reclamation has achieved certain results. According to the data, at present, about150 thousand mu of abandoned land has been reclaimed in China, accounting for 8% of the total amount of abandoned land; Among them, more than 6 million mu of industrial and mining wasteland was reclaimed, accounting for 10% of the total industrial and mining wasteland. 70% of the reclaimed land is used as cultivated land or other agricultural land, and 30% is used as non-agricultural construction land or other purposes. From the perspective of coal industry, during the Ninth Five-Year Plan period, coal mining subsidence land was reclaimed 1.50 ha, with a reclamation rate of 1.5%, and open-pit coal mining land was completed, with a reclamation rate of 4 1%. ?
(3) The treatment effect of three wastes is remarkable. During the ninth five-year plan period, the utilization rate of coal gangue reached 40%, 9 percentage points higher than that during the eighth five-year plan period; By the end of 1999, there were 3 10 fire-extinguishing waste hills, and the fire-extinguishing rate reached 80%. 1998, Shandong province comprehensively utilized more than 7 million tons of coal gangue, accounting for 7 1% of the total discharge, and realized profits and taxes of nearly 70 million yuan. The new coal mine design refuses to pile up gangue, which will effectively ensure the complete eradication of gangue hill in the future. Statistics show that 1999, the national extractive industries * * * removed industrial SO2 156 104 t, of which 41505t; Is removed in fuel combustion; Removal of industrial dust 1647893t.
(4) The greening of mining area has changed from planting trees and grass to green ecological engineering construction. Many mining areas continue to increase investment, greening and beautifying production and living areas. According to the geographical environment of the mining area, actively adopt new greening technology, build shelter forests in the mining area, green coal gangue hills, control sand and consolidate soil, restore vegetation and maintain water and soil. ?
(5) Clean coal technology has developed rapidly. 1995, there were 557 coal washing plants in China, with an annual raw coal washing capacity of 280 million tons and a raw coal washing rate of 22%. By 2000, the number of coal washing plants had increased to 755, the raw coal washing capacity reached 450 million t, and the raw coal washing rate exceeded 30%. Before 1995, there was almost no power coal blending in China. During the Ninth Five-Year Plan period, a number of power coal blending plants with different specifications and types were completed and put into operation, with an annual production capacity of nearly 60 million tons. China civil briquette technology has matured. By the year 2000, the national civil briquette output will reach 80 million tons, and the urban residents' briquette popularization rate will reach 80%. In order to speed up the development of coalbed methane, during the Ninth Five-Year Plan period, the State Council approved the establishment of a company specializing in coalbed methane development. According to incomplete statistics, China has developed and utilized nearly 400 million cubic meters of coalbed methane in 2000. It is predicted that by 2005, the utilization of coalbed methane in China will reach more than 3 billion cubic meters. ?
Weak links of environmental protection and governance in coal mining areas
(1) Leaders have weak environmental awareness and low public participation. The historical experience of China's environmental protection proves that all environmental pollution and ecological destruction first come from the ideological understanding and decision-making behavior of leaders at all levels. At present, many leaders are far from establishing a real awareness of environmental protection, and only stay on the slogan of sustainable development, taking the old road of "pollution first, then treatment", or taking the crooked road of aggravating pollution for local interests. Public participation plays a very important role in environmental impact assessment in developed countries. Listen to public opinions extensively through hearings and other forms to meet the public's requirements for environmental protection. At present, the public participation system has not been established in the environmental impact assessment of construction projects in China, and the public's supervision over environmental protection is still very low.