1. Closed circle and classification
of open-pit mines Closed circle: the plane closed curve of the surface of the open-pit mine.
of hillside opencast mine and sunken opencast mine A – Hillside opencast mine, B – Sunken opencast mine, 1 – Surface enclosure elevation
Platform (flat plate): the space on the horizontal plane between the slope bottom line and the slope top line of the step. The width between the bottom line of the slope and the top line of the slope is called the platform width. The platform for blasting, shoveling and transportation is called the working platform. The width between the edge of the blasting pile and the top line of the slope is called the height of the working platform. The platform used to intercept the sliding rocks is called the safety (cleaning) platform.
Therefore, down-the-hole drills are now widely used in small and medium-sized mines at home and abroad, and are suitable for medium hard rock drilling.". 3.1.3.1
. One or several rock drills are installed on a special drill boom or bench together with an automatic propeller, and there is a traveling mechanism to realize the mechanization of rock drill operation.
3. In the total cost of open-pit mining, the blasting cost accounts for about 15% -20%. The quality of
blasting not only directly affects the efficiency of mining, transportation, coarse crushing and other equipment, but also affects the total cost of the mine. 3.2
.
Shallow-hole blasting is mainly used for the excavation and secondary blasting of open-pit mines or quarries, caverns and tunnels with small production scale, the treatment of new open-pit mine hills, the formation of single-wall trench transportation channels on hillsides and other special blasting. 3.2
. The deep-hole blasting of the open-pit mine is mainly the production blasting of the bench. Drilling equipment
for deep-hole blasting mainly includes down-the-hole drill and roller drill. It can be used to drill vertical deep holes or inclined blast holes. The charging of inclined blast holes is more uniform, and the blasting quality of ore and rock is better, which creates good conditions for mining and loading work.
In order to reduce the seismic effect and improve the blasting quality, such measures as millisecond blasting in large area, interval charging in blastholes or bottom air interval charging can be taken under certain conditions, so as to reduce the blasting cost and obtain better economic benefit. 3.2
. Open-pit mines are used only during the capital construction period and under specific conditions, and quarries are used when conditions permit and when there is a large demand for mining. 3.2.3
. In order to protect the slope, the blasting near the slope shall be strictly controlled. According to the experience at home and abroad, the main measures are millisecond blasting, presplitting blasting and smooth blasting. 3.3
. In order to give full play to the shock absorption effect of millisecond blasting, the key is to try to increase the number of blasting segments and control the millisecond interval. 3.3
. Because the pre-fracture separates the excavation zone from the slope, the seismic wave of the subsequent excavation blasting will produce a strong reflection on the fracture surface, which greatly weakens the seismic wave passing through it, thus protecting the slope. 3.3
. The difference between smooth blasting and presplitting blasting is mainly in the initiation time. The initiation of the smooth blasthole is later than that of the previous rows of excavation boreholes, usually 50 to 75 ms later.
In addition, another measure is to control the blasting of the last few rows of boreholes. The explosive quantity and resistance line of the last rows of boreholes near the slope should be reduced, which is called "buffer blasting", which can reduce the damage of drilling blasting to the slope.
Main mining and loading equipment: excavator, dragline, hydraulic shovel and rubber-tyred front loader.
Mining and transportation are inseparable, and they influence and restrict each other. At present, the development trend of mining and transportation technology is mainly reflected in the large-scale of mining and transportation equipment, the integration and continuity of mining and transportation links, and computer automation.
5. Rock dumping
is the operation of the transportation terminal. The stripped topsoil and waste rock are transported to the waste rock yard for disposal. Rock
dumping process: rock dumping by railway transportation, rock dumping by road transportation, Belt transport dump
7. In the conventional mine drainage design process, there are generally the following four types of drainage facilities:
The first type is the open-pit mine with hillside characteristics, and we generally adopt the gravity drainage system.
The second is suitable for mining areas with small water area and small water flow, and they can use the bottom centralized drainage system.
The third method is suitable for those mining areas with deep mining and large water flow, that is, the use of sectional interception drainage system.Another
is suitable for open-pit mines with very large water inflow, which can adopt underground mine drainage system. These four drainage systems can be used with each other and according to the actual situation.
In addition to the need to pay attention to drainage, waterproofing should also be paid attention to. In the daily operation of the mining area, some waterproofing facilities and waterproofing materials should also be checked regularly to ensure that they can be used at the first time when problems arise.
8. Problems
of mines after open-pit mining Problem 1: a large amount of water accumulated in open-pit mining pits and high and steep open-pit slopes. Landslide disaster
will occur. Water accumulation in open pit will cause hidden danger
to underground mining. Landslide will cause huge rock burst underground.
Problem 2: The dam failure of tailings reservoir will cause landslide and debris flow in the upstream of the reservoir area. Causing huge disasters
to downstream villages Problem 3: Tailings discharged from tailings reservoirs seriously affect the local ecological environment
9. Top ten open-pit mines
in the world 9. The entrance of the cave is 1200 meters in diameter and 525 meters in depth, equivalent to 161stories in height. The depth of the spiral hole has caused the magnetic field inside the earth to form a strong current with the air above the surface. If a small aircraft with too light weight flies over it, it can be sucked into the cave by the airflow.
9.2 Bingham Canyon Gold and Copper Mine, located in Bingham Canyon, Utah, USA, is the largest and deepest open-pit mine on earth, with a depth of 1200 meters and a width of 4000 meters. Covering an area of 1900 acres (about 7.9
), the mine produces 800000 ounces of gold annually (22). The mine is 3.5 kilometers long and 1.9 kilometers wide
. Located in Cape Province, South Africa, it is said to be the largest hand-dug pit with a depth of 1097 meters. More than 3 tons of diamonds were produced before it was closed in 1914.
9. Originally an open-pit mine, underground production began in early 2010. By 2012, open-pit mining in Davik ceased and has now become a completely underground mine.
9. Only 200 kilometers south of the Arctic Circle, the surrounding climate is cold, the environment is extremely difficult, and the access to the Aikadi mine has to pass through the thrilling ice and snow road, but the huge profits still drive people to work in such a harsh environment. According to statistics, in the ten years from 1998 to 2009, miners mined 45 million carats (about 8000 kilograms) of diamonds in this mine. 9.9
. The mine is now 850 metres deep. In prehistoric times, humans began mining here. The annual production capacity of copper concentrate is 510 thousand tons, and the output is about 450 thousand tons. With the depletion of resources, the mining life of the main mining area is 10 years, but the resources of other ore bodies nearby are enough for mining for 40 years.
9. It is worth mentioning that the ore of the mine is called "percussion drill", which is produced by the impact of extraterrestrial objects such as meteorites on existing diamond mines, and its diamond hardness is twice that of ordinary diamonds. Because of this unique physical property, they are more popular in the high-tech and industrial markets.
10. Under the guidance of the new development concept of "innovation, coordination, green, open and sharing"
in the new era, the construction of ecological civilization in China has entered a stage of in-depth development. The following provides some methods of mine repair:
10. Therefore, when repairing the mine development area, we should first consider the treatment of the slope.
If the slope is unstable during the development of the mine, it will cause damage to the relevant development personnel and equipment to a large extent. Only by taking some measures to maintain the stability of the slope, can we avoid landslides, collapses and other phenomena.
At present, the biological slope protection method is mainly used in the slope control of mining areas in China, which is a comprehensive technology that uses organisms (mainly plants) alone or with other structures to protect the slope and restore vegetation. Specifically, it includes the following points:
first, try to maintain the smoothness of the mine pavement;
second, repair the cliff, remove dangerous rocks, reduce the slope and cut the slope, try to form a horizontal step on the cliff that has not formed a step, and reduce the slope below the safety angle to eliminate the hidden danger of collapse;
Then, the treated slope is re-greened, and green plants are planted within the area of the slope, so that the slope can be further stabilized and the environment can be beautified.
10. Therefore, special attention must be paid to the secondary utilization of tailings and its comprehensive benefit level in the remediation measures of tailings. The
main method is to use the underground goaf as the filling material of the goaf to discharge the tailings, so as to achieve the optimal utilization level in the overall mine development area.
In addition, the comprehensive recovery and utilization of useful components of tailings resources should be done as far as possible, and advanced technology and reasonable process should be adopted to re-select tailings, so as to maximize the recovery of useful components in tailings, so as to further reduce the amount of tailings.
In addition, the tailings, which can not be fully exploited, can also be commercialized and recycled as raw materials for building materials to produce cement, silicate tailings bricks, tiles, aerated concrete, cast stone, refractory materials, glass, ceramsite, concrete aggregate, microcrystalline glass, slag tiles, foam glass and foam materials. It can also be used to build roads, pavement materials, anti-skid materials, coastal reclamation and so on, so as to achieve the ultimate goal of waste reuse.
10. Therefore, soil improvement is one of the most important links in the ecological restoration of abandoned mines. There are mainly three ways to optimize and improve
the soil:
taking soil from other places, that is, taking a proper amount of soil without destroying the soil from other places, moving it to the seriously damaged part of the mine, and planting plants on the soil. The damaged soil is filled and repaired through the absorption, volatilization, root filtration, degradation, stabilization and other functions of plants.
The abandoned land is transformed, that is, before the surface soil is transformed, the slurry is poured to wrap the waste residue, and then a layer of clay is laid and compacted to form an artificial aquiclude to reduce the infiltration of the ground water and prevent the release of highly toxic elements in the waste residue. To fertilize the
land, that is, to add effective substances to improve the physical and chemical properties of the soil, so as to shorten the process of vegetation succession and accelerate the ecological reconstruction of abandoned mines. In this way, the purpose of recycling mine resources can be achieved, and it is also conducive to improving the comprehensive output of the relevant mine development zones.
10.
To plant plants in abandoned mine sites, tree species with strong adaptability, fast growth and strong stress resistance are generally selected. For example, heavy metal tolerant plants can adapt to adverse environments such as poor soil structure and extreme barrenness in abandoned land, and can also tolerate heavy metal toxicity. In addition, the selection of different plants according to the climatic conditions of different regions is conducive to speeding up the remediation process of heavy metal pollution in mines. When planting
vegetation, there are two modes of operation:
the first is to directly cover the mine development area with vegetation. This method is simple and fast, and the cost is not particularly expensive. However, this method is slow to take effect.
The second is to cover the soil with vegetation. Generally speaking, this method is more widely used, which can improve efficiency while ensuring the amount of capital investment.
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