Overview of mining and mining goaf processing

After returning to the mining house by the majority of the empty field mining method and the filling mining method, the top column, the bottom column and the inter-column are generally left. In thin and extremely thin veins, the reserves of the pillars account for 5-10% to 15-20% of the ore reserves, and the thickness of the thick and medium-thick mineral bodies can reach 35-50%, individually to 55-60%. Due to the large reserves of pillars, the annual mining volume of the pillars will account for an important part of the annual ore production of the mine. According Fankou lead zinc mine statistics, the ratio of reserves over the years for the production phase: stope 42% between columns accounted for 46.7%, 10.3% top-pillar, other 1%. Copper Copper Mine officials in 1981 and 1982, the amount of ore pillar mining accounted for 43.73% and 53.25%, respectively, the annual output. It can be seen that the mining work of the pillar will directly affect the total technical and economic effects of the mine, reflecting the production technology and management level of the mine.

The goaf formed by the open field method, with the advancement of the mining work, the exposed area is getting larger and larger, the exposure time is getting longer and longer, the ground pressure will increase continuously, and the empty area will fall and the pillar will be deformed and destroyed. The ground pressure phenomenon such as the difficulty in maintenance of the stope in the adjacent operation area may be caused by high stress (especially tensile stress) or lithology and geological structure development, and large-scale sudden caving and rock movement occur to the production. And security has serious consequences. August 1956, Gongchangling iron ore large-scale ground pressure, then No. 2 shaft scrapped; August 1963, due to a sudden caving surrounding rock, the backstage area 200kW No. 1 main fan crashed into an empty area. Tin, antimony ore mine in May 1965, December 1966 and 1970, three large empty area caving roadway destruction of more than 4,000 meters, the No. 1 Vertical Shaft cracking, WELLS deflection, surface cracking building, mining and earth pressure surge, difficult Mining recovery, mining recovery rate dropped by 15 to 25%. The two large-scale empty areas of Pangushan tungsten mine from 1966 to 1967 (especially the second time) destroyed the seven major process systems of the whole mine. The value of lost resources reached 24.8 million yuan, and the production capacity decreased by 45% for four consecutive years. . The Ximu lead-zinc mine was subjected to three times of pressure in June-August 1973, causing the three-stage pillar to collapse and losing 380,000 tons of ore. Such an example is not uncommon, but the characteristics and impact of the process are different. The high-speed air waves and shock waves formed when the empty area suddenly falls over a large area are very harmful to the equipment and personnel in the roadway. The surrounding rock of the Shouwangyu copper mine suddenly fell and the surface collapsed. The next stage, within 90m from the center of the fall, launched more than 80 tons of ore, of which the large ore weighed 1.1~2.0t, adjacent to the wood. The closed wall was destroyed, the wind, water and electricity systems were destroyed, and the ramp workers outside the 300m were blown down. It can be seen from the above that the goaf must be processed in time.

Our metal and nonmetal mines have done a lot of work in the mining and processing ore column empty area, has accumulated considerable experience, but compare and stope mining is still relatively backward, in: 1, a large pillar backlog. According to the statistics of 31 non-ferrous mines in 1983, the ore mine volume reached 31 million tons, of which several mines have a column volume of 100-3.8 million tons, accounting for 33-40% of the mines; some mines have not returned in time. The mining column has increased ground pressure activities and lost 100,000 to 400,000 tons of ore. 2. A large number of empty areas have not been processed. According to statistics in 1983, the untreated empty areas of more than 40 non-ferrous metal mines reached 3,634.918 million cubic meters, accounting for 44% of the total area. 3. The research, theory and practice of mining and empty area treatment are weak, technically urgent, and technical and economic indicators are still poor, and ore loss is very poor. In particular, it is more difficult to recover the top and bottom columns, and there are fewer effective methods. The ore and the column are close to each other, and more research is needed.

The above situation is derived from: 1. Insufficient understanding of the necessity of returning to the mining column and handling the empty area in time; 2. Scientifically mastering the stability conditions of the empty area, predicting the consequences of instability requires a process; 3. Processing the empty area requires considerable Manpower and material resources, pillar mining is technically more difficult than mine mining, and when the relevant policies are not perfect, it leads to short-term behavior in mine operations.

Pillar mining and empty area handling should follow the following principles:

First, unity. Mining and pillar mining are two mutually inter-conditional steps in the mining process. The mining of the pillars is affected by the conditions formed by the mining houses, but it is counterproductive to the selection of mining schemes and processes. In a certain sense, whether the problem of pillar recovery can be reasonably solved is the pros and cons of the two-step mining method; this is especially true when the ore body is thick and the ore value is high.

The size, shape, treatment method and time of the empty area will affect and adjust the stress of the adjacent section rock mass, thus affecting the mining operations in these sections; the distribution time and spatial relationship of the mining area and the empty area processing The methods used vary from one to another; the technical and economic evaluation of mining methods should include empty area processing in order to meet the principle of comparability.

Therefore, the broad meaning of mining methods should include the entire process of mining, pillar recovery and empty area processing. Considering only one of them will be biased, it should be based on the optimal comprehensive effect of the mining and mining process, and put the mining pillar mining and empty area processing in a complete mining system and process to solve their problems uniformly. Engineering layout, structural parameters, work sequence, mining process and technical and economic evaluation, this is a basic starting point to discuss the treatment of pillars and empty areas.

The selection of the mine, pillar design and empty area treatment plan should be carried out at the same time. The number, type and size of the pillars must meet the requirements of the mine recovery and the requirements for the recovery of the pillars. Generally speaking, the mining of thin veins should be left with less sand columns or by artificial columns; if the loss of mining is too large, the size of the pillars should be as small as possible; however, if the size of the pillars is more reliable, it is better to increase Large pillar. The layout of the mine mining project should be as close as possible to the needs of the back mining column. The parameters of the mining room and the mining process should consider the supporting capacity of the pillar and keep it intact, which provides better conditions for the pillar mining.

Second, timeliness. Whether the pillars can be recovered in time is very different. The Shouwangfen copper mine usually recovers the ore pillars after mining the mines. The ore mines account for only 6.2% of the mines (as of August 1983), and the pillars are rarely difficult to recover. In other mines, the mining of the pillars lags far behind the mines. The ore reserves of the pillars account for 50-60% of the mines, causing problems. The first-stage pillar of a copper mine was recovered too late, and the ground pressure increased and only 8% was recovered.

The advantages of timely and timely return to the mining column are also as follows: the goaf can be treated in time to control the ground pressure, eliminate hidden dangers, reduce the maintenance cost of the roadway, shorten the mining operation line, facilitate centralized management, improve the utilization rate of the approved roadway, and avoid unnecessary Repeat the cutting work, improve the utilization of equipment, and so on.

If the stage transportation level is pulsed outside, there is no service in the whole stage or several ore blocks, and the transportation, ventilation and filling system of the previous stage will not be destroyed due to the return of the mining column, and the mining will not be affected, and the mining will be reversed. The number of blocks can guarantee the mine production capacity, and mining and pillar mining can be carried out at the same stage. Under normal circumstances, the mining column mining lags behind the mining room mining should not exceed one stage, that is, the lower stage mining room, the upper stage mining column. The reasonable hysteresis value should be determined according to factors such as the stability of ore and surrounding rock, the length of the stage, the quantity of reserves and the number of ore divided, the mining method used, the mining and mining method of the pillar, the annual production of the mine, and the mining sequence adopted. Continuous mining is not left or only temporary pillars are retained, which is a technical route for development at home and abroad.

The progress of mining, pillar mining and empty area treatment projects shall be included in the mining planning and mining plan in a reasonable mining order, so that the mining room, the pillar mining and the empty area handling will be coordinated.

Third, reasonableness. In order to promote the timely return of the mining column and the treatment of empty areas, comprehensive and correct technical and economic analysis of the pillar recovery should be carried out from the aspects of resource utilization, safety and economic benefits. The technical conditions for mining the pillars are more complicated and difficult than those for mining, and the technical and economic indicators for mining are generally lower than those for the mines. However, due to the development cost, the cutting cost shared with the mine house and the pipeline laying cost, etc., it is irrelevant to the mining ore mining. The mining cost of the pillar is only the additional mining, mining and other related expenses required for the returning of the mining column. composition. Therefore, its economic effects must be lower than that of the mine. Much depends on the mining method used and whether the recovery is timely.

Most of the pillars are stress-concentrated parts, which are cut by the mine and the roadway. It is also destroyed by the blasting power of the mine, and its technological conditions such as ground pressure management, mining, and ore mining are different from those of the mine. Therefore, it is impossible to follow the experience of mining mining, and the corresponding technical measures should be adopted according to the special conditions of mining.

In order to reduce the cost of empty area treatment and improve the technical and economic effects of mining and empty area treatment, strict management and systematic research work should be carried out, such as: empty area monitoring and stability judgment, pillar size, empty area treatment method and its effect. Mechanism, thickness of ore rock or isolation layer, reasonable size and type of closed culture, mining method of mining column, reasonable process matching and time-space relationship of mine mining, pillar recovery and empty zone treatment.

The mining method of the pillars is divided according to the state of the mines before the mining. 1. The pillars of the open-pit mines are harvested; 2. The pillars of the mines are filled.

The method of empty area treatment is divided into: 1, filling method; 2, caving method; 3, permanent pillar technical support method; 4, isolation failure; 5, joint method.