Block Caving Mining Method

Block Caving Mining Method
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Block caving is an underground mining method that involves undermining an ore body and allowing it to collapse under its weight, allowing huge volumes of rock to be extracted efficiently. The ore then falls into a series of draw tunnels, where it can be collected and transported to the surface. The method is a high-volume mining method often used to mine large, low-grade ore deposits that are too deep or too large to be mined by open-pit methods pit due to the economical depth limit of open-pit mining. It is also a relatively safe mining method because there is no need for miners to enter the caving area.

How Block Caving Works

Block caving mining operation

Block caving involves undermining an ore body, allowing it to progressively collapse under its weight. This is accomplished by first creating a series of horizontal tunnels, or drifts, beneath the ore body. These drifts are then connected to a series of vertical tunnels, or raises, that extend to the surface. The intersection of the drifts and raises creates a grid of underground chambers. Next, a large section of the ore body is undercut, creating an artificial cavern. As the ore body collapses, it fills this cavern with broken rock and rubble. This broken ore falls into the pre-constructed network of drifts and raises, where it can be extracted continuously. The collapse of the ore body progresses upward through the ore body, eventually causing large surface areas to subside into sinkholes. This subsidence is a natural consequence of block caving and is carefully managed to minimize environmental impact.

Some of the factors that need to be considered include the size and shape of the orebody, the rock conditions, and the desired production rate. The block-caving mining method is typically carried out in the following steps:

  1. Block caving subsidence zone at San Manuel copper mine

    Preparation: A network of tunnels is excavated beneath the ore body. These tunnels will be used to extract the ore and to provide access to the draw points.

  2. Undermining: The ore body is undermined by drilling and blasting. This creates a void beneath the ore body, which allows it to cave in.
  3. Caving: The ore body collapses under its weight, filling the void created in step 2. This process is gradual and can take several years to complete.
  4. Extraction: The ore is extracted from the draw tunnels and transported to the surface.

Some of the advantages of block-caving mining include the following:

  • High production rates
  • Low operating costs
  • Relatively safe mining method
  • Can be used to mine large, low-grade ore bodies
  • A high degree of mechanization and automation
  • Small surface footprint and low waste disposal requirements

Some of the disadvantages of block-caving mining include:

  • Long development time
  • High initial capital investment
  • Requires careful planning and execution
  • Not suitable for all orebodies and rock conditions

Examples of block-caving mines include:

  • El Teniente Mine in Chile
  • Northparkes Mine in Australia
  • Grasberg Mine in Indonesia
  • Resolution Mine in the United States

Overall, block caving is a valuable mining method that can be used to extract large volumes of ore from deep underground. It is a complex and challenging method, but it is also very efficient and safe and it is becoming increasingly popular around the world.

Below is an illustration of the block-caving method:

Read more about the caving method:

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