At present, many achievements have been made in the research and treatment of spontaneous combustion coal gangue hill, mainly including two aspects.
1. spontaneous combustion mechanism of coal gangue hill
Since17th century, people have been exploring the spontaneous combustion mechanism of coal, and the spontaneous combustion of coal gangue hill was not studied by scientists all over the world until the end of19th century. With the aggravation of the spontaneous combustion hazard of coal gangue hill and the continuous improvement of people's awareness of environmental protection, scientists all over the world have made fruitful research on the spontaneous combustion mechanism of coal gangue hill at the end of the 20th century and the beginning of this century. Although there is not much controversy about the oxidation theory of pyrite in coal gangue, there is still much controversy about how the early stage of coal gangue spontaneous combustion began, that is, what is the mechanism of coal gangue low-temperature oxidation spontaneous combustion. Therefore, Anthony and Howard have done more detailed and pioneering work in the analysis of coal volatile matter; Smith and others have carried out research work on carbon oxidation; Williams and Annamalai theoretically studied the ignition theory of heterogeneous reaction. People put forward a series of arguments to explain the spontaneous combustion of coal gangue, which can be summarized as follows: pyrite oxidation theory, coal oxidation combined spontaneous combustion theory, bacterial action theory, free radical action theory and volatile matter theory.
2. Study on prevention and control technology of spontaneous combustion in coal gangue hill.
Once the coal gangue hill is ignited, it is very difficult to put out the fire, and the spontaneous combustion process often lasts for years or even decades. At present, although there are many fire extinguishing methods, they are not only costly, but also difficult to rule out the possibility of re-ignition. Some coal gangue mines put out fires again and again, and spent a lot of money. Therefore, the best way to control the spontaneous combustion of coal gangue hill is to nip in the bud and take effective preventive measures to eliminate the hidden danger of spontaneous combustion and protect the atmospheric environment in the mining area. In western developed countries, the fire prevention and extinguishing work of coal gangue hill mainly starts with the study of different stacking methods of coal gangue to solve the spontaneous combustion problem of coal gangue hill. The research shows that the natural accumulation, compaction accumulation and layered compaction accumulation of coal gangue have great influence on the airflow velocity of coal gangue pile. The traditional cone-shaped coal gangue hill has the largest flank area, and the air is easy to enter to form thermal convection circulation. The strength of coal gangue during dumping contributes to the "stack effect". Therefore, many countries use the method of layered compaction to pile up coal gangue and control the compaction degree of coal gangue to solve the spontaneous combustion problem of coal gangue mountain. The most fundamental way to put out the burning of coal gangue hill is to isolate the infiltration of air and inject fire extinguishing materials into the burning area of coal gangue hill to achieve the purpose of cooling, isolating oxygen and fixing sulfur, so as to put out the burning of spontaneous combustion coal gangue hill. The fire extinguishing methods of spontaneous combustion coal gangue hill at home and abroad mainly include: surface sealing method (covering method), leveling compaction method, foam method, controlled combustion method, shotcrete method, pouring method, excavation fire extinguishing method, deep grouting method and so on. As early as 198 1, the fire fighting project was carried out in the coal gangue hill of Fenxi Mining Bureau, and the method adopted at that time was to inject lime slurry. The concentration of lime slurry is high, and the irrigation methods are divided into manual irrigation and mechanical irrigation. When watering artificially, it is necessary to dig pits and ditches in the fire area and inject lime slurry into the pits and ditches; Mechanical irrigation does not dig trenches and pits in the fire area, but uses the pressure of sewage pump to spray lime slurry directly on the surface of the fire area. Deep grouting method is a low-cost and effective method commonly used in China at present.
In 1990s, Shanxi Yangmei Group carried out research and practice on fire prevention and extinguishing in coal gangue hill, and made a long and difficult exploration on fire prevention and extinguishing methods in spontaneous combustion coal gangue hill. After many investigations, No.1-No.4 Coal Mine carried out fire-fighting tests such as ground guniting, deep-hole grouting and covering, No.5 Coal Mine (New Mine) carried out layered gangue discharging and covering rolling tests, and No.4 Coal Mine carried out land reclamation tests, which accumulated a lot of valuable experience in fire-fighting management of spontaneous combustion coal gangue hills and formed its own characteristics in fire prevention and extinguishing.
In order to overcome the shortage of single fire extinguishing method, Yangmei Group integrated the advantages of loess covering rolling method and grouting method, designed a fire extinguishing scheme with rolling covering as the main method and local grouting as the auxiliary method, selected appropriate fire extinguishing process parameters, and conducted further research and practice in coal gangue hills such as No.2 Mine and No.3 Mine, and obtained successful experience and remarkable environmental, economic and social benefits.
At the same time, it is also recognized that the unreasonable way of gangue discharge is the external cause of gangue spontaneous combustion, so the original gangue discharge technology is changed from "condescending, natural dumping, and continuous extension of gangue discharge slope" to "bottom-up, reducing volley, layered compaction and surrounding coverage". By adopting a new way of discharging gangue, the problem of spontaneous combustion of newly discharged gangue is basically eliminated.
Second, the ecological disaster caused by spontaneous combustion of coal gangue in China
At present, the safety situation of coal gangue mines in China, especially those with spontaneous combustion or potential spontaneous combustion, is not optimistic. The ecological, environmental and safety problems of coal gangue hill are increasingly prominent, and safety problems are reported from time to time.
On September 6, 2009, the coal gangue hill of Qishan Mine in Xuzhou, jiawang district, Xuzhou City, Jiangsu Province collapsed, causing two women to be buried and died on the spot.
On June 5, 2008, Luojiawuji Coal Mine in Renhe District, Panzhihua City, Sichuan Province washed away the retaining wall of coal gangue hill due to accumulated rainfall, which caused coal gangue to slide down and flooded four sheds below, killing three people and injuring four others.
On May 3rd, 2007, the gangue hill of Yuejin Coal Mine of Henan Yima Coal Industry Group Company collapsed naturally, resulting in 1 death and 3 injuries, all of which were severe burns.
On March 18, 2007, a large pit where coal gangue was piled suddenly collapsed in Shajingou Village, Nanpiao District, Huludao City, Liaoning Province, and all six people who were picking up coal cinders were killed.
On June165438+1October 17, 2006, the Tanlei River in Gansu was attacked by coal gangue, and the drinking water source of 20,000 people was threatened, which led to the tension between workers and peasants.
On July 28th, 2006, a coal gangue hill about 50m high collapsed in Jiangzhuang Coal Mine of Zaozhuang Mining Bureau, Shandong Province. A dump truck was buried and four drivers were burned to death in the car.
On June 26th, 2005, 10, the gangue hill of Lindong Coal Mine in Chongqing suddenly collapsed in a large area, and 1 the student disappeared.
On July 3, 2005, a coal gangue hill near Houyu Village, Xiajiazhuang Town, Boshan District, Zibo City, Shandong Province collapsed. Someone was injured in the accident, and some villagers nearby had to find a hotel to settle down temporarily.
On May 15, 2005, two spontaneous combustion and collapse disasters occurred in the gangue hill of No.4 Mine of Pingdingshan Coal Group, in which 8 people were killed and more than 0/00 people were injured, including 6 seriously injured.
On March 1 1, 2005, two women who came from other places to work in Liaoning were smoked down on the coal gangue hill in Ximafeng Coal Mine, dengta city, Liaoyang. Although he was rescued, he died because he was not found in time.
On June 5th, 2004, the gangue hill in Lindong Coal Mine of Nantong Mining Company collapsed and caused landslide, which destroyed 4 households in Xinhua Village/KLOC-0, killed 2/KLOC-0 and injured 3 people.
On February 28th, 2004, the gangue hill of Xinji Coal Mine in Huainan City, Anhui Province collapsed due to the use of gangue, resulting in 9 deaths.
On 200 1 May 13, an explosion accident occurred in the gangue hill of Yangquan No.1 Mine, causing1person to die.
1975 an explosion accident occurred in the collapse area of shangyao, Gansu province. The mushroom cloud is as high as 100 meters, and the temperature within 200 meters reaches 500 degrees, causing 20 deaths and more than 40 serious injuries. Trees within two kilometers were burned, and the air environment of 12km2 was seriously polluted, resulting in smoke and dust lasting for several days.
After the spontaneous combustion of Dongpinggou coal gangue hill in Yangquan, the original mountain spring pool under the coal gangue hill lost its drinking value, its chromaticity changed, and it became extinct, making 10 people suffer from cancer.
An accident of poisoning death caused by spontaneous combustion of gangue occurred in Benxi mining area, Liaoning Province.
It can be seen that the geological disasters and environmental pollution in coal gangue hill are on the rise year by year, which has become a more prominent problem in coal mining enterprises. Moreover, most geological and environmental disasters in coal gangue mountain are directly related to the spontaneous combustion of coal gangue, which has become one of the focuses of coal mine safety production at present. Therefore, the control of spontaneous combustion coal gangue hill has become one of the most urgent topics in mining area. Coal mining enterprises should earnestly do a good job in safety production, especially in the safety management of coal gangue hills, so as to prevent accidents.
Three. Urgency of harnessing and ecological reconstruction of spontaneous combustion coal gangue hill in China.
The treatment of coal gangue hill is a very urgent task that benefits the country and the people and future generations, and it is also the requirement of the sustainable development of China's coal industry. Due to China's national conditions, the utilization rate of coal gangue is low, most coal gangue is still accumulating, and new coal gangue hills are still emerging. The spontaneous combustion of coal gangue hill caused a series of environmental and social problems, which seriously affected the development of mining area. Therefore, it is urgent to control coal gangue hills, especially spontaneous combustion coal gangue hills. Scholars at home and abroad have studied the causes and mechanism of coal gangue spontaneous combustion in many aspects, but in the end, due to the complex composition and external reasons of coal gangue, no clear conclusion has been drawn, and there are still many vague places about the mechanism of coal gangue spontaneous combustion. Some experiences have been gained in the practice of coal gangue fire fighting in various places. It is reported that the success rate of governance in the United States is less than 50%, while that in China is even lower. So far, there is not a successful system experience and a completely successful example. Most of them were successful in the early stage and failed in the later stage, that is, they revived after several years of successful governance. At home and abroad, the fire extinguishing methods of coal gangue hill mainly include fire source excavation, grouting, covering, controlled combustion, foam (gel) method, low temperature inert gas method and so on. However, these fire extinguishing methods all have their own advantages and scope of application, and also have certain limitations.
Studies at home and abroad show that the greening of coal gangue hill is one of the effective ways for the disposal and utilization of mine solid waste. Under the condition of low comprehensive utilization rate of coal gangue in China, greening of coal gangue mountain is the most effective way to solve the environmental problems in mining areas and the best way to properly protect the potential energy value of coal gangue. Many mining areas in China have also carried out the practice of greening waste hills, and many waste hills 10 have been afforested, most of which have not spontaneously ignited or have spontaneously ignited. Spontaneous combustion coal gangue piles are often extinguished, without considering the in-situ control of pollution and greening. The fire extinguishing methods are mostly deep grouting with alkaline slurry or oxygen-insulated surface covering, but the effect is often unsatisfactory and often reignites. Therefore, we should change the practice of fire fighting in spontaneous combustion coal gangue hill, take the greening and ecological reconstruction of spontaneous combustion coal gangue hill as the goal, and organically combine fire fighting with in-situ pollution control and greening to achieve the goal of systematically and effectively controlling spontaneous combustion coal gangue hill.
Fourth, the problems and development prospects of spontaneous combustion coal gangue in China.
In view of the present situation of the treatment and greening of spontaneous combustion coal gangue in China, we believe that the greening of spontaneous combustion coal gangue mountain needs to solve the following six problems:
1) How to consider the requirements of greening and choose fire control measures, so as to organically combine fire control and greening in coal gangue hills;
2) How to prevent the reburning and fire prevention of the gangue hill and how to prevent the acidification of the gangue hill;
3) How to prepare and shape spontaneous combustion gangue hill;
4) How to control the in-situ pollution of spontaneous combustion coal gangue hill;
5) How to choose suitable plant population, reasonable planting techniques and tending management measures for the greening of spontaneous combustion coal gangue hill;
6) How to organically combine the above technologies and processes to form a technical method for greening spontaneous combustion coal gangue hill.
The above problems are the technical difficulties to be solved urgently in the disposal and utilization of coal gangue in China. Although some methods have been put forward and practiced in the fire extinguishing and greening technology of spontaneous combustion of coal gangue in China, how to organically combine fire prevention, in-situ pollution control and greening technology to realize the ecological restoration of spontaneous combustion of coal gangue remains to be explored.