Open pit mining and production scale

1. Definition of stripping ratio

Stripping ratio: the ratio of the amount of stripping to the amount of mined ore. In addition to mining ore, open-pit mining also requires a large amount of stripping of rock, which is an important difference between open-pit and underground mining;

Average stripping ratio: the ratio of the total stripping Vp in the mining boundary to the mined volume Ap. Vp/Ap; the stripping ratio of the boundary: after the unit depth is increased by open pit mining, the new stripping amount ΔV and the newly added mined amount △A Ratio ΔV/△A,;

When stripping surface mining or no greater than the cost of not less profit than underground mining, ore generally cost comparison, cost comparison and metal profitability comparison;: economical stripping ratio nj

The essence of open-pit mining: under the premise of ensuring the safety of the formation, that is, the stability of the slope, the stripping ratio is minimized, that is, the mine is mined at the least cost, and the stability of the slope is determined by the nature of the rock;

2. Selection of mining forms

All underground mining, upper open-pit mining underground mining, all open-pit mining (too little ore), under normal circumstances, can use the open air without underground, stripping ratio is the criterion for selecting mining methods;

The maximum depth of open-pit mining is generally determined by the ratio of the stripping ratio of the boundary to the average stripping ratio not greater than the economically reasonable stripping ratio; when the lower part must also use underground mining, the cost is generally determined by nj; The amount is not much, use the profit method to determine nj, that is, as long as there is profit, then another step;

3. Choice of mining methods

The kind of open up the way: roads, railways, tape, adit chute, skip the slopes and joint development; construction period to open up different modes of transport, infrastructure investment, operating costs, system capabilities are different;

The principle of choice of pioneering methods: early production, fast production, low investment, low operating costs; design must include a multi-program technical and economic comparison of development methods;

Influencing factors of development methods: geological and topographic conditions, ore body occurrence status, plant selection location, transportation distance, production capacity, infrastructure construction and infrastructure construction period, loss depletion rate, equipment supply;

Comparison of development plans: infrastructure construction, construction investment, construction period, production capacity, operating expenses, loss depletion, system reliability, infrastructure investment and operating expenses are key indicators; sag open pit mines like stadiums, hillside open-pit mines like terraces;

4. Economic production scale

Iron ore scale: generally refers to the original ore, large-scale open-air is more than 2 million tons, small is less than 600,000 tons, and underground iron ore is more than 1 million tons;

Influencing factors: total amount of recoverable and stratified ore, reasonable service life, number of equipment that can be arranged, depth of mine engineering, equipment ratio (wearing, loading, transporting, discharging and discharging); !

Expansion potential: The mineral bed's own conditions determine its economic scale, not how much it wants;

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