3 Elements of Open-pit Mining and Their Selection Factors

Mines where ore is exposed to the surface are called open-pit mines. The essence of the open-pit mining process is the space transportation of large-scale rocks. That is, a certain part of the earth's crust is extracted in a certain time and space sequence, and useful minerals and temporarily useless stripping are respectively transported to the predetermined places.

This article mainly introduces the mining process of the open pit deposit from the following three aspects: open-pit mining process, development and transportation system design and waste dump planning. Among them, the quarry and waste dump constitute the two main projects of the open-pit mine, and are the "skeleton" of the open-pit mine system. And the external transportation system is the "throat" of the open-pit mine.

Open-pit mining process refer to the procedure for the completion of ore stripping and ore extraction in an open-pit stope, including the division of mining and stripping bench, the determination of the initial position of mining and stripping works, the horizontal advancement and vertical extension of mining and stripping works, and the composition of working slope.

In the process of open-pit mining, the ore and rock in the mining boundary should be divided into benches with a certain height. The mining engineering of each bench includes trenching and enlarging. Realize the extension of mine engineering through bench trenching, establish transportation links and form bench work lines. Then promoting the enlarging with a certain mining width to complete all the benches of the mining engineering.

Selection Factor

Factors affecting the choice of mining process are: ore occurrence conditions, size and geometry of open-pit mines, process types, development methods, and ore output, ore quality, starting time of production, and finished time of production, etc.

Open-pit mine development refers to the establishment of various working levels on the ground surface and the open-pit mine and the ore rock transportation channels between them to ensure the transportation of the open-pit mine and prepare new work levels in time.

In the design of development and transportation system, the layout of transportation pit lines (i.e. the pit lines formation, location and quantity, plate form and its fixed characteristics) in the whole mining process of the deposit should be determined according to the selected transportation equipment and transportation forms, so as to establish the transportation routes necessary for mining. Once the development system is formed, if you want to reform it, it will seriously affect production and cause great economic losses.

Selection Factor

The main factors affecting the design of the development system are: the natural conditions of deposit occurrence, size of open-pit mining boundary, production capacity, type of technology and equipment, procedure of deposit development, general layout of mining area, relevant state technology, economic policies, supply conditions of equipment, speed of mine construction, ore output and requirements, mining life and so on.

One of the important features of open-pit mining is to strip the soil and rocks covering the upper of deposits and surroundings, and transport them to a dedicated site for disposal. Such special sites for the discharge of rock and soil are called waste dump or waste-rock yard.

Open-pit metal mines generally use external discharge (discharge outside the pit). Open pit coal mines are discharged outside first, then inside (discharged into the pit). This is determined by the characteristics of the deposit.

Selection Factor

The main factors affecting waste dump planning are: geological conditions of the ore deposit, the haul distance from the open pit, the safety distance regulations, the stability of the dump and the slope, the total amount of ore stripping, land reclamation planning, etc.

Before mining, the preliminary design of the mining procedure and development and transportation system will be done, but it will be different in actual construction. During the mining process, the first mining area (initial ditch location) must be determined according to the deposit conditions first. This is because the investment of open-pit mine is large, and the mineral must be seen quickly to relieve economic pressure. Then, digging trenches on the vertical surface and expanding the slope on the plane to realize the continuous development of the open-pit mine project. Finally mining to the boundary, and close the pit.

If your economic conditions permit, it is better to find a company with the qualification of EPC mining services to plan the mining project, so as to maximize the benefits of open-pit mining.

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