Key engineering science and technology strategy for green, intelligent and sustainable development of deep metal mines in China

(3) High temperature environment control and cooling technology

The common mine cooling technology at home and abroad includes two categories: non-artificial refrigeration and artificial refrigeration. Non-artificial cooling technology mainly includes mine ventilation, heat source isolation, rock precooling, goaf filling and other methods, among which mine ventilation is the most widely used. However, the mine ventilation cooling cost is high and the ventilation efficiency is low. In addition, for the mine with more serious heat damage, the non-artificial cooling technology is difficult to meet the cooling requirements, and artificial cooling measures must be adopted at the same time. At present, artificial cooling technology is widely used in metal mines, including water cooling system and cold cooling system. The water cooling system produces cold water through the refrigeration unit, and then through the high and low pressure heat exchanger and air cooler, the ventilation system is input into the underground air flow cooling, and sent to the working face to cool down. This system is actually the application of air conditioning technology in underground mines. The ice cooling system sends granular ice or mud ice produced on the ground to the underground ice melting pool through wind or water power, and uses the working face return water to spray the ice melting, and sends the cold water after the ice melting to the working face for cooling through the air cooler or spray cooling. In general, non-artificial cooling technology and artificial cooling technology are passive cooling technology. Engineering practice shows that these two cooling technologies not only have high cooling cost, but also have unsatisfactory cooling effect in deep Wells.

In order to effectively solve the problem of deep well cooling, active cooling technology must be developed, focusing on the following two directions:

① Deep well high-temperature rock insulation technology. The high temperature environment of deep Wells is mainly caused by the heat radiation of high temperature rock formations. The development of new and efficient heat insulation materials, new technologies and new processes can isolate the high temperature heat sources of rock formations. On this basis, artificial refrigeration and cooling technology can play a more obvious cooling effect.

② Deep well geothermal development technology. Geothermal itself is a natural energy source, and the existing cooling technology is a passive measure, treating geothermal as a kind of disaster prevention. If heat exchange technology is used to develop and utilize geothermal resources in rock strata in the process of deep mining, the combination of deep well mining and deep geothermal development can greatly offset the cooling cost, thus opening up a subversive and economic and effective technical way for the cooling of deep mining Wells.

(4) Improving technology

Lifting is as important a link in the mining process as rock excavation. Multi-rope friction or winding hoists are widely used in metal mines. After entering deep mining, the steel wire rope is continuously lengthened and thickened, which not only increases the lifting load, greatly reduces the effective lifting capacity, but also due to the large change in the length of the tail rope, resulting in excessive changes in the tension of the lifting steel wire rope, resulting in broken wire damage, which has become the main factor restricting the safety of friction lifting. According to domestic and foreign statistics, the maximum single-stage lifting height of friction and winding elevators is only about 1800 m and 3000 m respectively. Greater lifting height must be multi-stage lifting, which greatly increases the cost of equipment and greatly reduces the efficiency of upgrading.

When the lifting height exceeds 3000 m or 4000 m, the large load, large inertia and large torque caused by the rope lifting technology will be an unsolved problem. To this end, it is necessary to develop cordless vertical lifting technology, such as linear motor drive lifting technology and magnetic levitation drive lifting technology. Cordless vertical lifting technology has the advantages of small size, flexible movement, high efficiency and unrestricted lifting height, which is suitable for deep well lifting. At present, the technology and equipment in this area are still in the preliminary stage, and more in-depth innovative research and scientific experiments are needed in the future to develop practical technologies and products. It is suggested that China should focus on the research and development of such upgrading technology and equipment in the future.

Fourth, green intelligent mining mode

The traditional shallow mining mode and mining method are not suitable for deep high stress field, high well temperature, rock mass structure change and complex geological conditions. In order to meet the requirements of green intelligent mining of deep metal mines and improve the level of automatic and efficient mining of deep Wells, it is necessary to fundamentally change the existing mining mode and process technology.