Mining

Mining refers to the exploitation of natural mineral resources of useful value by hand or machinery. According to the difference of burial depth of mines and the requirements of technical and economic rationality, mining is divided into open-pit mining and underground mining. Open-pit mining is carried out close to the surface and shallower parts, and underground mining is used in the deep.

For an ore body, whether it is open-pit mining or underground mining depends on the occurrence of the ore body. If open-pit mining is used, it should be more reasonable. There is a problem of depth boundary. The determination of the depth boundary depends mainly on economic benefits. Generally speaking, if the boundary stripping is less than or equal to the economically reasonable stripping ratio, open pit mining may be used, otherwise underground mining methods will be adopted.

(1) Open pit mining

Open-pit mining is a mining method in which the excavation of rock and the production of useful minerals in one stage and one stage is carried out under the conditions of open conditions in the open conditions or open pits of the hillside. Compared with underground mining, open pit mining has many advantages, such as fast construction speed, high labor productivity, low cost, good working conditions, safe work, high ore recovery rate, and low depletion loss. Especially with the development of large-scale high-efficiency open pit mining and transportation equipment, open-pit mining will be more widely used. At present, the majority of black metallurgy mine open pit mining.

The whole process of building an open pit mine generally includes: construction of ground facilities in the mining area; dewatering and drainage of the deposit; basic construction of the open pit and a series of preparatory work for production.

The open-pit construction project is mainly to dig into the driving ditch, the exit ditch and the opening ditch, to lay transport routes, to construct dumping sites, to strip rocks and to construct water supply and drainage and power supply facilities.

Access to the ditch is the establishment of a ground-to-work level and a sloping transport path between work levels. The open trench is the horizontal channel that is drilled at each level to open up the mining work line, which is the initial working line of the development phase.

Trenching, stripping and mining are three important aspects in the production of open pit mines. The speed of the decline of the open pit mine and the length of the new level of preparation time are mainly determined by the trenching speed. In order to ensure the continuous normal production of open pit mines, there must be a certain advance relationship between space digging, stripping and mining. Follow the principle of “extraction and stripping, stripping first” to organize production.

In the open pit production process, whether it is stripping or returning to the ore, the process is generally through perforation, blasting, loading and transportation. At present, the equipment used in China's ferrous metallurgy mines, the main perforations are roller drills and down-hole drills, and impact drills have been eliminated. Most of the loading equipment uses 3 to 4.6 m 3 electric shovel, and 6 m 3 or more electric shovel is also used. Most of the transportation equipment uses 20 tons to load heavy vehicles and 80 to 150 tons of electric vehicles, and 100 tons of electric wheel vehicles are also promoted in some extra-large mines.

(2) Underground mining

When the deposit is buried deep below the surface, the open-pit mining will make the stripping coefficient too high. After technical and economic comparison, when underground mining is reasonable, underground mining is adopted.

Due to the deep burial of the ore body, in order to extract the ore, it is necessary to cut the roadway from the surface to the ore body, such as shaft, inclined shaft, slope road, and alley. The key point of underground mine construction is to excavate these wells and lanes.

Underground mining mainly includes three steps of development, cutting (acquisition and cutting work) and recovery. Pioneering is a wellhead excavation project such as shafts, inclined shafts, slopes, and alleys that are excavated by the surface of the ore body. The mining is based on the development of the project, and preparations for the return of the ore, including mining preparation lanes such as roadway, cross-country and patio. Cutting is the well engineering that must be completed before the mining operation according to the mining method according to the mining and mining engineering, such as cutting the patio, cutting the alley, pulling the roadway, cutting the trench, discharging the funnel, rock drilling Room and so on. Mining is the mining in the stop, including rock drilling and caving, ore and support mining. These three steps are started in sequence. After the mine is put into production, in order to maintain normal production, it is still necessary to continue to drill various wells. Such as extending the development of roadways, excavating various prospecting,

Picking, mining, etc. In terms of time, it is necessary to follow the production rules of “exploiting ahead of the standard, picking ahead of the mining, and ensuring that the production and preparation of minerals at all levels reach a reasonable retention period”. This is a scientific law that is consistent with the practice of mining production through long-term production practice.

When mining underground deposits, it is generally the first stage of mining and the later stage of mining. In the stage, along the direction of the deposit, it is divided into ore blocks (the height of the ore is generally 40-60 meters, and the foreign country is generally 60-120 meters, or even 200 meters). Generally, the ore block is used as the basic unit or the ore block is subdivided. Mining for the mine and the pillar.

There are many underground mining methods, which are mainly divided into the following three categories:

(1) Natural support mining methods. The mining area is divided into mine houses and pillars. When returning to the mining room, the formed goaf is supported by the pillars. Therefore, the basic condition for using such mining methods is that the ore and surrounding rock need to be stable.

(2) Artificial support mining methods. In the mining area, with the advancement of the mining face, the artificial support method is used to maintain the goaf and form a work site.

(3) Caving mining method. It is a method of controlling the management of ground pressure by caving the surrounding rock with the collapse of the ore. Since the rock caving in the upper and lower plates will cause the surface to collapse, the surface allowable caving is a necessary prerequisite for the use of such mining methods.

Underground mining, whether it is development, mining or mining, generally has to go through rock drilling, blasting, ventilation, loading, support and transportation upgrading.

At present, the equipment used in key underground mines in China is mainly used for rock drills , rock drilling rigs and medium-deep holes and deep-hole drilling rigs for mining. Loading is mainly carried out by loaders, scrapers, electric picks, and the like. The alley transportation is generally upgraded by the electric vehicle to the shaft, the inclined shaft, the lifting shaft and the site, and then the cage is used to lift the mine to the ground. The large underground mines discharge the ore from the mine into the mine. Reload the bucket to the ground.

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