Mining Projects: Exploitation Phase & Methods of Mining

Once a mining company has constructed access roads and prepared staging areas that would house project personnel and equipment, mining may commence. Typically, production levels are during which production is gradually increased towards design capacity within the transition period after development.  It is not uncommon commissioning period, sometimes over 12 months in the mining industry.

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Figure 01: Open pit diamond mine of Mirny in Yakutia

Although all types of active mining share a common aspect: the extraction and concentration (or beneficiation) of a metal from the earth, proposed mining projects differ considerably in the proposed method for extracting and concentrating the metallic ore (Adapted from Miller et al., 2016).

Exploitation in the life of a mine, is not only the culmination of the three preceding stages (e.g. prospecting, exploration and development), but the end process by which the three previous starts and the fifth stage, reclamation, are economically justified. Basically, exploitation is the work of recovering mineral from the earth in economic amounts and delivering it to shipping or processing facilities. Therefore, exploitation or production phase are associated with the daily activities of obtaining (extracting) a saleable product from the mineral reserve on a commercial scale, including any processing before sale. Although some exploration and development may continue, the emphasis in the exploitation stage is on production of marketable minerals. Usually, only enough exploration and development are done prior to exploitation to ensure that production, once started, can continue uninterrupted throughout the life of the mine. In the mining production process, a number of extractive unit operations are employed, the primary ones constituting the production cycle and the secondary ones the auxiliary or support operations (Adapted from Hartman and Mutmansky, 2002).

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Figure 02: Udachnaya diamond mine, Russia

Selection of an appropriate mining method is a complex task that requires consideration of many technical, economic, political, social, and historical factors. The appropriate mining method is the method which is technically feasible for the ore geometry and ground conditions, while also being a low-cost operation. This means that the best mining method is the one which presents the cheapest problem.

Characteristics that have a major impact on the mining method selection include:

  • Physical and mechanical characteristics of the deposit such as ground conditions of the ore zone, hangingwall, and footwall, ore thickness, general shape, dip, plunge, depth below the surface, grade distribution, quality of resource, etc. The basic components that define the ground conditions are: rock material shear strength, natural fractures and discontinuities shear strength, orientation, length, spacing and location of major geologic structures, in situ stress, hydrologic conditions, etc;
  • Economic factors such as: capital cost, operating cost, mineable ore tons, orebody grades and mineral value;
  • Technical factors such as: mine recovery, flexibility of methods, machinery and mining rate;
  • Productivity factors such as annual productivity, equipment, efficiency and environmental considerations;
  • Environmental and Social factors: The physical, social, political, and economic climate must be considered and will, on occasion, required that a mining method be rejected because of these concers;

Each of these criteria can become the principal determining factor in method selection, but the obvious predominance of one consideration should not preclude careful evaluation of all parameters (Adapted from Bitarafan and Ataei, 2004).

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Figure 03: Access to underground mine

The strategy for conducting the exploitation stage of mining should be clear as mineral production begins. The cardinal rule of exploitation is to select a mining method that matches the unique characteristics (natural, physical, geologic, social, political, etc.) of the mineral deposit being mined, subject to the requirements of safety, mineral processing, and the environment, to yield the overall lowest cost and return the maximum profit. In stating this basic objective, health and safety of working conditions and community, environment protection and economic development of the local community must all be accorded the highest level of concern (Adapted from Hartman and Mutmansky, 2002).

Traditional exploitation methods can be classified into two broad categories based on locale: surface or underground. Surface mining includes mechanical excavation methods such as open pit and open cast (strip mining), and aqueous methods such as placer and solution mining. Underground mining is usually classified in three categories of methods: unsupported, supported, and caving.

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Figure 04: Coal mining, Lower Lusatia

It is critical to capture the benefits of the learning curve experienced within the first years of production. Even the best designed and planned mines will inevitably require changes along the way due to unanticipated issues and/or better knowledge of the deposit and required mining processes. The speed and effectiveness of these adjustments will make a significant difference to the initial profitability of the mining enterprise.

Recently, there have been multiple innovative methods and approaches to mining. Do you know what Asteroid mining is?

Kind regards,

Ronaldo

Follow me on twitter @rcrdossantos

References:

Miller, G. et al. ,”Guidebook for Evaluating Mining Project EIAs”, Environmental Law Alliance Worldwide (ELAW), University of Nevada at Reno, (July 2010). Last accessed on 06/05/2016 at https://www.elaw.org/files/mining-eia-guidebook/Full-Guidebook.pdf

Bitarafan, M.R. and Ataei, M. “Mining method selection by multiple criteria decision making tools”, The Journal of The South African Institute of Mining and Metallurgy, (October, 2004).

Hartman, H. L. and Mutmansky, J. M. “Introductory Mining Engineering”, Published by Wiley, Hoboken, NJ, USA , (August, 2002).

Photos Credit:

Feature: Absetzer im Tagebau Hambach. Author: Elsdorf-blog.de

Figure 01: The open pit diamond mine of Mirny in Yakutia. Author: Vladimir

Figure 02 : Udachnaya Diamond Mine, Russia.    Author: Stapanov Alexander

Figure 03: The Darkness Mine Stone. Author: Darius Sankowski

Figure 04: Pit Mining Brown Coal Lower Lusatia. Author: AFOK14

 

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