With the development of the mining industry and the increasing demand for mineral resources and their products, both developed and developing countries are considering the possession of resources and developing resources as strategic measures. As a result, the mining industry had developed many efficient, safe yet low-cost mining technologies and methods, so that keep up with the pace of advanced technology, as well as the increasingly strict enforcement of environmental protection regulations.
1.More intelligence underground mines
At present, the world’s underground mines are in pursuit of efficiency, safety, so the level of mechanization, automation level continues to improve.
Take the Swedish Kiruna iron ore mine, for example. Kiruna iron ore is famous for producing high grade (more than 70% iron ore) and is one of the largest iron ore mines in the world. It’s iron ore mining has been more than 70 years of history, has now been open-pit mining to underground mining. The intelligence of Kiruna iron ore mine is mainly due to the use of large-scale machinery and equipment, intelligent remote control system, as well as a modern management system, highly automated and intelligent mine systems, and equipment to ensure safe and efficient mining is the key.
- Pioneering. The Kiruna iron ore mine is jointly developed using shafts and ramps, and the mine has 3 shafts for ventilation, ore and stone lifting, and personnel, equipment, and materials are mainly transported from the ramp by railless equipment. The main lift shaft is located in the lower plate of the ore body, so far, the extraction surface and the main transport system have been moved down 6 times, the current main transport level at 1045m level.
- Drilling and blasting. Laneway excavation uses rock drilling trolleys, which are equipped with three-dimensional electronic assays, which can achieve precise positioning of drilling holes. The quarry rock drilling using the Simba W469 type of Simba W469 type of remote-controlled rock drilling trolley, aperture 150mm, the maximum hole depth of 55m, the car uses a laser system for accurate positioning, driverless, can be 24h continuous cycle operation. The annual amount of mine can reach 3 million t.
- Ore remote loading and transportation and lifting. The Kiruna iron ore mine has been intelligently and automated, and rock drills and scrapers have been unmanned. The ore is loaded with a Toro2500E remote-controlled scraper with a single efficiency of 500t/h. The underground transport system has tape transport and rail automatic transport 2 types. Rail automatic transport is generally composed of 8 columns of mine carts, minecarts for continuous loading, unloading of automatic bottom unloading vehicles, tape conveyors automatically transport ore from the crushing station to the metering device, with the shaft bucket to complete loading and unloading, the whole process is the remote control.
- Remote control concrete injection technology and support and reinforcement technology. Laneway support is provided by a joint anchor net, completed by a remote-controlled concrete jet, and the anchor and rebar network installation uses an anchor rail.
2. The widespread application of solubility technology
At present, in the recovery of low-grade copper, gold ore, uranium ore, etc. have been widely used solubility technology, in the soil immersion technology in situ leachings, heap immersion and situ crushing leaching three categories.
The United States, Canada, Australia, and other countries handle 0.15% to 0.45% of low-grade copper ore, more than 2% copper oxidation ore, and 0.02% to 0.1% uranium ore are recycled by heap immersion and in situ blasting leachate.
In the United States, for example, there are more than 20 mines that use insitu blasting to leach copper. For example, Mike Mine in Nevada, Zonia Copper Mine in Arizona produces copper per day above 2.2t, Butt Mine and Copper Queen Mine in Montana produce 10.9 to 14.97t of copper, u.S. dissolved copper production accounts for more than 20% of total production, gold production exceeds 30%, and the majority of uranium production comes from dipping mining.
3. Deep well mining technology
With the continuous reduction of resources, the depth of mining is getting deeper and deeper, mining depth to 1000m or less, bringing many in shallow mining did not encounter difficulties and problems, such as increased ground pressure, increased rock temperature, at the same time, lifting, drainage, support, ventilation and other difficulties also increased.
Deep Well Mine FAQ:
1) Boostability. Mining depth increased, the first encounter is the mine’s lifting capacity problem, the current lift machine lift the maximum height of more than 2000m, such as a Canadian lift of the deepest mine has reached 2172m deep, a gold mine in South Africa has a deep 2310.4m. At present, the ability to upgrade equipment has been able to fully meet the requirements of large-scale deep well mines.
2) Rock mild ventilation and cooling. The depth of mining increases, the rock temperature also increases, such as Japan’s Fengyu copper and zinc mine at the level of -600m (about 1200m from the surface) rock layer temperature has exceeded 100 degrees C, but many countries in the world stipulate that the underground temperature can not exceed 28 degrees C. Deep well mine generally adopts the increase of underground ventilation air volume and underground air cooling, that is, the use of air and water cooling 2 ways, the choice of one or both, in addition to trying to reduce the temperature, but also pay attention to reduce the cooling of underground machinery and equipment, underground diesel equipment cooling and underground cooling equipment itself cooling problems.
3) Ground pressure management and mining methods. Generally deep well mines should establish a complete set of ground pressure measurement and monitoring system, it is directly related to the mining production can be carried out smoothly and production costs. Rock explosion is a prominent problem encountered in deep well mining, in order to predict rock explosion, many mines have installed micro-seismic monitoring devices underground, such as the U.S. Rizhao Silver Mine on the 2254m level installed micro-seismic monitoring devices, 24h monitoring.
4) Self-ignition self-explosion. Deep well mining will also be due to the high temperature of the ore, resulting in the self-ignition of vulcanized ore and the phenomenon of self-explosion when filling explosives, but also to cause sufficient attention.
At this stage of China’s non-coal mining mountain mining depth is generally not more than 700 to 800m, but in recent years there have been a number of buried depth of about 1000m of the deposit is being developed, the copper tomb non-ferrous metals company belongs to the Dongguashan copper deposit, Jinchuan two mining areas are included in it.
4. Mine environmental protection work
In foreign countries, especially in developed countries, comprehensive management measures are adopted for the mining environment. Waste water, waste gas, waste residue and dust, noise, etc. discharged from mines have strict technical standards, many low-grade mines, because the cost of environmental protection management is too large to build and put into operation.
At present, foreign emphasis is also on the establishment of waste-free mines and clean mines, Germany’s Ruhr Industrial Zone Walsm coal mine is a successful example, with coal washing plant coal and coal power generation after burning coal ash and broken underground waste stone added cement by activation and stirring, with PM pump to the underground filling area, the mine does not discharge any solid waste.
5.Filling mining technology
Depending on the situation, different fillers are used:
1) Regional support. High-quality rigid filling is required to reduce the risk of elastic volume closure and rock explosion.
2) Rock layer control. The quality requirements for filling are not strict, but they are required to fill large, and the filling should not be shrunk.
3) Multi-mine mining. The requirement for filling is a low stress state, the filler should be rigid in order to keep the deformation displacement of the rock layer to a minimum.
4) Environmental control. In order to ensure that the upper plate is closed to avoid wind flow through the mining area, the filling is required not to shrink, for large area filling.
5) Reduce the lifting of waste stone. In the underground preparation and crushing of waste stone as filling, thereby improving the efficiency.
Questions to be considered at present:
1) Focus on forming a practical and reliable system. It is necessary to research and develop effective filling technology so that the filling operation and the mining operation cycle can be effectively combined. We should pay attention to the management of filling system.
2) Research can enable the existing system to achieve optimized design technology, study the composition of high-quality filling particle distribution, study in the hydraulic cyclone and crushing has been improved filling preparation process, research used to optimize the filling of the delivery technology such as pressure loss, wear, corrosion to optimize the overall design of filling system.
3) Strengthen the quantitative understanding of the preparation, transportation, charging and load deformation process of filling, and lay the foundation for safe, stable and efficient mining. At present, the international filling process is: water sand filling, dry filling, high water solid filling, glue filling. The glue filling is also divided into: segmented tail sand hydraulic filling (high concentration self-slip transport), other filling hydraulic filling (high concentration self-slip transport), full-tail edand body self-filling and full-tail sand paste pumpfilling. At present, the international recommendation is the whole tail sand paste pumpfilling.
At present, 12 mines in Canada have applied high concentration paste filling, South Africa and Australia also have a new paste filling system put into operation. The new filling process will be able to better meet the requirements of protecting resources, protecting the environment, improving efficiency and ensuring the development of the mine. Fillmining will have a wider outlook in the mining development of the 21st century.
6. Ocean polymetallic nuclear mining
Polymetallic nodules are deposited on the seabed at depths of about 3000 to 5000 m. A viable method of mining is necessary to mine. Therefore, the development of reliable mining methods in all countries of the world has given priority to the development of a large number of experimental studies, and some have even carried out deep-sea intermediate mining tests. From the late 1960s to the present, the ocean mining methods developed and tested in the world are mainly divided into continuous chain-to-chain bucket (CLB) mining methods, submarine remote control vehicle mining methods and fluid lift mining methods.
1) Continuous Chain Bucket (CLB) mining method. The method was proposed by the Japanese in 1967. The method is simple and mainly composed of mining ship, tow cable, cable bucket and tractor. According to a certain interval, the rope bucket is attached to the tow cable and put the human sea floor, the tow cable under the tow boat to do the rope bucket down, shovel ingress and uplink action, this stepless rope cycle operation constitutes a continuous acquisition loop. The main feature of the CLB is its ability to adapt to changes in water depth and keep it operating normally. But the clB method can only produce up to 100t/d. Far from meeting the requirements of industrial mining. As a result, the CLB mining law was abandoned in the late 1970s.
2) Submarine remote control vehicle mining method. This method was mainly proposed by the French. The submarine remote control vehicle is an unmanned diving mining vehicle, which is composed of four systems: mining mechanism, self-propelled propulsion, buoyancy control and ballast. Under the monitoring of the sea surface mother ship, the mining vehicle snuck into the sea floor in accordance with the instructions to collect nodules, filled with nodules surfaced and to the mother ship to receive the discharge of nodules, the sea mother ship can usually control several mining vehicles operating at the same time. The method of mining system investment, product value is not high, in a few decades without economic benefits, the French Ocean Tuberculosis Research and Development Association in 1983 stopped research, but this mining vehicle procurement principle is considered a promising acquisition technology.
3) Fluid lift mining method. At present, the international lysier is the fluid lift mining method, and the most industrial application prospects. The method is that when the mining vessel reaches the mining area, the collector and lift pipe are connected and gradually released to the marine vessel collection machine for the collection of nodules in the seabed sediments and for preliminary treatment, so that the water in the pipe moves upward at sufficient speed by hydraulic or hydraulic lift to transport the nodules to the offshore mining vessel.
With the advent of the sea in the 21st century, ocean mining technology is particularly important. The development of modern high-tech has laid a bridge for the development of ocean resources, and its formation and development will have a positive and far-reaching impact on the world marine economy, culture and human marine consciousness.
The development trend of mining technology in foreign mines is in addition to the six aspects mentioned above. There is also natural rock mining technology is becoming more and more perfect, the application is also expanding, in addition to rock drilling also has a large number of new technologies emerged, mining rock mechanics and engineering has been as an independent discipline. It is playing an increasingly important role in the construction and production of mines.