"In the current global economic slow recovery, China's economic structural adjustment of the depth of the situation, the global mining industry and China have entered a relatively difficult period. Pioneering advanced, non-traditional mining new theories, new technologies, it is to revitalize the metal mining industry The only way to go" - Cai Meifeng, academician of the Chinese Academy of Engineering.
The empty field method, the caving method and the filling method are three common mining methods for metal mines. Due to the high cost, the filling method is only used in mines with high mineral value.
In order to meet the requirements of green mining, reduce environmental pollution caused by mining and damage to the ecological environment, fundamental changes must be made to the traditional mining model and its process technology.
I. Mining process change
1. Mechanical continuous cutting and tunneling technology
Starting from the long-term goal, it is an important direction to replace the traditional blasting mining process with continuous cutting equipment by mechanical excavation and mechanical rock drilling. Because the blasting mining process first damages the stability of the surrounding rock, and the second is the mining of ore and waste rock, which greatly increases the workload of ore dressing and lifting.
advantage
1> Mechanical cutting can accurately mine the target ore and minimize the depletion rate of mining ore.
2> The cutting, mining, loading and transportation processes can be carried out in parallel and continuously, creating conditions for continuous mining.
problem
1> Mining machine operations are affected by the variety of metal deposits
2> Complex geological conditions and the life and cost of the cutting head
2. High-pressure water jet rock breaking and mining technology
High-pressure water jet technology is a new cleaning and cutting technology developed in the 1970s. Currently the high-pressure water jet for medium-soft rock and hard rock rock breaking has been achieved in the coal mine has wide application. However, the use of higher water jet pressures in the crushing of hard ore rocks can result in reduced reliability and longevity of the jet launcher system.
In order to solve the problem of hard rock breaking, the high-pressure water jet needs to develop toward ultra-high voltage and high power. It is possible to use for rock breaking under hard rock conditions in metal ore.
3. Laser rock breaking and mining technology
Laser rock breaking is the rapid heating of the rock by the heat generated by the high-energy laser beam, and the three types of rock breaking, crushing, decomposition, melting and vaporization are sequentially realized with the increase of temperature.
Mining rock breaking can be done as long as it is broken. When a high-energy laser acts on the rock surface, the rock locally expands rapidly and causes local thermal stress to rise. When the thermal stress is higher than the ultimate strength of the rock, the rock will undergo thermal fracture to achieve cutting and rock breaking.
4. Plasma rock breaking and mining technology
The technology uses electric energy to convert the electrolyte in the blasthole into a high-pressure, high-temperature plasma gas, which is rapidly expanded by the plasma gas to form a shock wave, which produces a blasting effect similar to explosives. The pressure generated by the blasting can exceed 2 GPa, which is high enough to break the hard rock. The implementation of this technology can greatly improve the working environment and reduce the impact and damage of traditional blasting on surrounding rock and environment.
Second, the support process revolution
5, paste filling mining technology
Usually, due to the high cost, only some mines with high mineral value use the filling method.
However, in order to achieve green mining, control rock movement and surface subsidence, protect nature and ecological environment; effectively control the deep ground pressure activities of deep mining, and avoid the occurrence of various disasters caused by instability of roadway and stope, the filling mining method will be most mines include iron ore, mining method had to choose. This is a major change in the traditional mining model.
However, the principle of balancing mining value with support costs is still to be observed. In order to reduce the filling costs, major reforms must be made to the filling process and filling materials. The full tail sand paste filling can obtain high quality filling body under low cement consumption condition, which can effectively maintain the empty area and control the rock burst. It represents the development direction of this technology.
China Jinchuan Company adopts this technology to prepare a paste with a concentration of 81%~83% with Gobi gravel aggregate, full tail sand and cement, and the compressive strength of the filling body reaches 10MPa or more. We should conduct further research in this area and create conditions for widespread application.
Third, the selection and transformation of integration
6, mining and selection integration technology
Downhole pre-selection and tailing technology. Before the ore raises the ground, pre-selection and pre-enrichment are carried out downhole, and most of the waste rock is thrown away, which can significantly reduce the amount of ore lifting.
Slurry conveying technology. For deep mining, the ore is pre-selected and crushed in the well, ground into a slurry, and sent to the surface concentrating plant by pipeline transportation. It is a technology with development potential. Compared with other transportation schemes, pipeline hydraulic transportation has a series of advantages such as low capital investment, strong adaptability to terrain, no occupation or less land occupation, small disturbance of continuous operation due to external conditions, high degree of automation and reliable technology.
The concentrator is built underground. Directly transporting concentrate to the ground after underground ore dressing can greatly reduce the amount of waste rock lifting, which is an important way to solve the problem of improvement. At the same time, waste rock and tailings remain in the underground for filling in goaf, achieving in situ utilization, and reducing pollution and damage to the ecological environment after discharge to the ground, which is an important means to achieve waste-free mining. Moreover, there is no concentrating plant and tailings pond on the ground, which saves the cost of land acquisition and construction of tailings ponds and tailings ponds, and plays a multi-faceted role.
Fourth, mining technology change
7, no waste mining technology
The goal of non-waste mining is to minimize the output and emissions of waste, improve the comprehensive utilization of resources, and reduce or eliminate the negative impacts of mineral resources development.
Therefore, mining activities should follow the industrial ecology point of view, link the mine ecological environment, resource environment and economic environment, obtain the maximum resources and economic benefits with minimum emissions, and fully protect the ecological environment.
To achieve waste-free mining, we must first adopt a mining method with a small cutting ratio, vigorously reduce the depletion rate of ore, minimize waste production, and control the output rate of waste rock from the source.
At the same time, it is necessary to improve the technical level of mineral processing technology, maximize the recovery rate of mineral processing, comprehensive utilization of resources and utilization rate, reduce tailings emissions; develop innovative mineral processing technology and equipment, and make the ore resources unavailable due to low level of metallurgy Minimize ingredients.
Through the pre-selection of underground and the selection of the plant in the underground, the waste rock and tailings will not be discharged, and it will be used for backfilling the goaf to realize the effective utilization of the selected waste on site.
Strengthen comprehensive recycling, realize the recycling of waste, improve the overall utilization level of waste, and strive to achieve zero discharge and zero storage of mine solid waste.
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