What should happen before mining

In another study an NRC panel concluded that controlled blasting methods could generate strong enough signals for analysis and suitable for geotechnical investigations NRC, b.

Other sensing methods that could be explored include electromagnetics and ground-penetrating radar. Combinations of sensing methods should also be explored to maximize the overlaying of multiple data sets. The second major area that requires additional research is data processing methods for interpreting sensor data. The mining industry has a critical need for processing algorithms that can take advantage of current parallel-processing technologies.

Currently, the processing of seismic data can take many hours or days. Real-time turnaround in minutes in processing will be necessary for the data to be useful for continuous mining. The third area of need is data display and visualization, which are closely related to the processing and interpretation of data. The data cannot be quickly assessed unless they are in a form that can be readily reviewed. The need for visualizing data, especially in three dimensions, is not unique to the mining industry.

In fact, it is being addressed by many technical communities, especially in numerical analysis and simulation. Ongoing work could be leveraged and extended to meet the needs of the mining industry. With look-ahead technology unexpected features and events could be detected and avoided or additional engineering measures put in place to prevent injuries and damage to equipment.

The economic benefits of anticipating the narrowing or widening of the mined strata or other changes in the geologic nature of the orebody would also be substantial.

Mechanized cutting of rock for underground construction and mining has long been a focus area of technology development NRC, a. For coal and soft rock, high-production cutting tools and machines have been available for some time and continue to be improved, especially in cutter designs that minimize dust and optimize fragment size for downstream moving and processing. Hardrock presents much more difficult problems.

Tunnel-boring machines can cut hardrock at reasonable rates, but the cutters are expensive and wear out rapidly, and the machines require very high thust and specific energy the quantity of energy required to excavate a unit of volume.

In addition, tunnel-boring machines are not mobile enough to follow sharply changing or dipping ore bodies. Drilling and blasting methods are commonly used to excavate hardrock in both surface and underground mining. Blasting is also used to move large amounts of overburden blast casting in some surface mining operations. Improved blasting methods for more precise rock movement and better control of the fragment sizes would reduce the cost of overbreak removal, as well as the cost of downstream processing.

Recommended areas for research and development in cutting and fragmentation are the development of hardrock cutting methods and tools and improved blast designs.

Research on the design of more mobile, rapid, and reliable hardrock excavation would benefit both the mining and underground construction industries. Early focus of this research should be on a better understanding of fracture mechanisms in rock so that better cutters can be designed NRC, b. In addition, preconditioning the rock with water jets, thermal impulses, explosive impulses, or other techniques are promising technologies for weakening rock, which would make subsequent mechanical cutting easier.

Novel combinations of preconditioning and cutting should also be investigated. Numerous ideas for the rapid excavation of hard rock were explored in the early s, motivated by the defense community.

These concepts should be re-examined in light of technological improvements in the last 20 years that could make some of the concepts more feasible Conroy et al. Improvements in blast design e. New methods of explosive tailoring and timing would also have significant benefits. Research into novel applications of blasting technology for the preparation of in-situ rubble beds for processing would help overcome some of the major barriers to the development of large-scale, in-situ processing methods.

New developments in micro-explosives that could be pumped into thin fractures and detonated should be explored for their applications to in-situ fracturing and increasing permeability for processing. These methods would also have applications for coal gasification and in-situ leaching. The development of better and faster rock-cutting and fragmentation methods, especially for applications to hard rock and in-situ mining, would result in dramatic improvements in productivity and would have some ancillary health and environmental risks and benefits.

Mechanized, continuous mining operations are recognized as inherently safer than conventional drill-and-blast mining because it requires fewer unit operations, enables faster installation of ground support, and exposes fewer personnel to hazards. Continuous mining methods for underground hard-rock mining would also raise the level of productivity considerably.

The environmental risks associated with in-situ mine-bed preparation by injection of explosives or other means of creating permeability will have to be evaluated.

This evaluation should include the hazardous effects of unexploded materials or poisonous by-products in the case of chemical generation of permeability. Current thinking is that these risks would not be high relative to the risks of the processing operations used in in-situ mineral extraction e. The planning and design of virtually all elements of a mining system—openings, roadways, pillars, supports, mining method, sequence of extraction, and equipment—are dictated by the geological and geotechnical characterization of the mine site.

The objective of ground control is to use site information and the principles of rock mechanics to engineer mine structures for designed purposes. Massive failures of pillars in underground mines, severe coal and rock bursts, open-pit slope failures, and roof and side falls all represent unexpected failures of the system to meet its design standard.

These failures often result in loss of lives, equipment, and in some cases large portions of the reserves. Mining-related environmental problems, such as subsidence, slope instability, and impoundment failures, also reflect the need for more attention to the long-term effects of ground control on mine closures and facility construction.

Advances in numerical modeling, seismic monitoring, acoustic tomography, and rock-mass characterization have contributed immensely to the evolution of modern, ground-control design practices.

Problems in mine design and rock engineering are complicated by the difficulties of characterizing rock and rock-mass behavior, inhomogenity and anisotropy, fractures, in-situ stresses, induced stress, and groundwater. The increasing scale of mining operations and equipment, coupled with the greater depths of mining and higher extraction rates, will require improved procedures for ground-control design and monitoring and improved prediction systems for operational ground control.

Site-characterization methods for determining the distributions of intact rock properties and the collective properties of the rock mass will require further development of geostatistical methods and their incorporation into design methodologies for ground support NRC, b. In addition, ground-support elements, such as rock bolts, could be installed at selected locations and instrumented to monitor stress, support loads, and conditions to determine maintenance intervals to validate ground-support designs.

With rapid advances in mathematics and numerical modeling, research should focus on approaches, such as real-time analysis and interrogation of data with three-dimensional models.

In addition, the heterogeneity of rock strata and the diverse processes acting on the mine system e. The technology development advocated for look-ahead technologies should also be beneficial for assessing stability in the immediate vicinity of mining. The failure of ground control has been a perpetual source of safety and environmental concern. Establishing and adopting better engineering approaches, analytical methods, and design methodologies, along with the other characterization technologies described above, would considerably reduce risks from ground-control failures and provide a safer working environment.

The design and proper operation of clearance systems for transporting mined materials from the point of mining to processing locations are critical for enhancing production. In many cases the system for loading and hauling the mineral is not truly continuous.

Belt and slurry transportation systems have provided continuous haulage in some mining systems. Longwall systems in underground mines, bucket-wheel excavator systems in surface mines, and mobile crushers hooked to conveyor belts in crushed-stone quarries are successful steps in the development of a continuous materials-handling system. Even in these systems haulage is regarded as one of the weakest components. In most cases, both in underground and surface mining, the loading and hauling functions are performed cyclically with loaders and haulers.

The major problem in the development of continuous haulage for underground mining is maneuvering around corners. To increase productivity a truly continuous haulage system will have to advance with the advancing cutter-loader.

If the strata conditions require regular support of the roof as mining advances, the support function must also be addressed simultaneously. Therefore, research should also focus on automated roof bolting and integration with the cutting and hauling functions. The increasing size of loaders and haulers in both surface and underground mines has increased productivity. However, larger equipment is associated with several health and safety hazards from reduced operator visibility. Research should, therefore, focus on advanced technology development for integrating location sensors, obstacle-detection sensors, travel-protection devices, communication tools, and automatic controls.

Reducing the amount of material hauled from underground mines by clearly identifying the waste and ore components at the mine face would result in both energy and cost savings, as well as a reduction in the amount of waste generated. It might even lead to leaving the subgrade material in place through selective mining. For this purpose the development of ore-grade analyzers to quantify the metal and mineral contents in the rock faces would be extremely useful.

The ore-grade analyzer must have both real-time analysis and communication capability so operations could be adjusted. Similarly, in surface mines the down-hole analysis of ore in blast holes could lead to more efficient materials handling by identifying ore and waste constituents. Equally important to improving the performance of materials-handling machinery will be the development of new technologies for monitoring equipment status and for specific automation needs.

In addition, for underground applications the interruption of the line of sight with satellites and thus the impossibility of using the GPS means a totally new technology will have to be developed for machine positioning.

Transporting ore for processing can take considerable time and energy and can contribute significantly to the overall cost of production in both surface and underground mining operations. An area for exploratory research should be downstream processing while the ore is being transported. For certain processes transport by conveyer-belt systems and hydraulic transport through pipelines would allow for some processing before the ore reaches the final process mills. Physical separation processes, such as those outlined later in this report, and leaching with certain chemical agents are the most likely processes that could be integrated with transport.

The initial transport of materials is currently done by powered vehicles. In underground mining the use of diesel-powered loading and hauling equipment presents both safety and health challenges. Electric equipment has similar disadvantages, even though it is cleaner and requires less ventilation, because power transmission and cabling for highly mobile equipment complicates operations. Equipment powered from clean, onboard energy sources would alleviate many of these health and safety problems.

Research could focus on powering heavy equipment with alternative energy sources, such as new-generation battery technology, compressed air, or novel fuel-cell technology. The development of such technologies may have mixed results from an environmental standpoint. On the one hand, a reduction in the use of fossil fuels would have obvious benefits in terms of reduced atmospheric emissions.

On the other hand, the manufacturing and eventual disposal of new types of batteries or fuel could have environmental impacts. The industry needs improved overall mining systems. Alternative systems may bear no resemblance to existing systems, although they may be innovative adaptations of the productive components of existing systems e.

From technological and management perspectives several characteristics of a mineral enterprise must be taken into account. Each mineral deposit has unique geological features e. For example, the environment of an underground mine is totally enclosed by surrounding rock. Because mine development is an intensive cash-outflow activity, the current long lead times must be decreased through new technologies.

The problem of low recovery from underground mines is well documented. In underground coal mining the overall recovery in the United States averages about 55 percent; average recovery from longwall mines is about 70 percent Hartman, Technology for mining thin coal seams less than 1 meter thick , particularly thin-seam longwall technology, would be beneficial. In view of the extreme difficulties for workers in such a constricted environment the technology for thin-seam longwalls must include as much automation, remote control, and autonomous operation as possible.

Successful longwall and continuous coal mining technology might be adapted to the mining of other laminar-metallic and nonmetallic deposits. Potential problems to be overcome will include the hardness of the ore, the rock conditions and behavior, and the abrasive nature of the mined materials. Underground mining of thick coal seams more than 6 meters thick also presents numerous problems.

Current practice is to extract only the best portion of the seam with available equipment. In some cases coal recoveries have been as low as 10 percent. In addition to the sterilization of the resources this practice has created problems of heating and fire.

Research should focus on equipment and methods specific to mining thick seams. Hydraulic mining may have potential applications for thick seams. The technical feasibility of hydraulic mining is well established, but equipment and systems that can operate in more diverse conditions will have to be developed. Like the mining of thick coal seams, other mining methods also leave a relatively high percentage of the resource in the ground.

Therefore, research could focus on secondary recovery methods i. The petroleum industry has successfully developed secondary recovery methods; steam, carbon dioxide, and water flooding are commonly used to drive oil to the wellheads. In-situ mining discussed in more detail later in this chapter has been remarkably successful for several metallic and nonmetallic deposits.

The application of this technique to the secondary recovery of mineral resources is another area for research. Extensive trials on in-situ gasification of coal have been conducted by a number of agencies worldwide, including DOE and the former USBM.

In-situ mining has also been attempted for retorting oil shale. The potential benefits of the in-situ gasification of energy resources include reduction of mine development and mining and more efficient use of resources that are otherwise not economical to mine Avasthi and Singleton, However, substantial technical problems, including such environmental issues as groundwater contamination, must first be addressed. A long-standing need of the hardrock mining industry is continuous mining.

Currently, only tunnel-boring machines and some prototype road headers have been shown to be capable of mining hardrock. The use of tunnel-boring machines in some mining operations has been limited because they are not very mobile, are difficult to steer, and are completely inflexible in terms of the shape of the mine opening. Tunnel-boring machines are being used more often for mine entry, as in the development of a palladium-platinum mine in Montana. Prototype mobile mining equipment for hardrock was demonstrated in Australia, but production rates were lower than expected, and numerous failures occurred.

The solution to this problem will depend largely on the development of advanced cutting technology for hard rock, as well as ways of incorporating new cutting concepts into a mining system that would provide efficient continuous mining with a lower thrust requirement and maximum flexibility.

New control systems might incorporate sensor feedback from the cutting head so machine parameters could be adjusted for maximum efficiency. Similar concepts are currently being used in the hydrocarbon drilling industry. Mining systems that make a clear break with present systems, such as the chemical and biological mining of coal, should also be investigated.

In-situ chemical comminution might be possible if the solid coal could be reduced to fragments by treatment with surface-active compounds, such as liquid or gaseous ammonia, and transported to the surface as a suspension in an inert gas. The literature on the biosolubilization of coal and the aerobic and anaerobic conversion of coal by microorganisms and enzymes has been evolving for some time Catcheside and Ralph, Biodegradation of coal macromolecules could potentially convert coal carbons to specific, low-molecular-mass products.

Research will be necessary to determine the basic mechanisms, as well as to develop conceptual schemes that would make biodegradation cost effective. For all in-situ mining concepts the obvious environmental benefits of limiting surface disturbances and waste generation must be weighed against the potential of adverse impacts on groundwater quality during operation of the mine and upon its closure.

Research on chemical or biological mining of coal must also include evaluations of environmental risks posed by reagents and process intermediates. Mining depends heavily on mechanical, motor-driven machinery for almost every aspect of the process, from initial extraction to transport to processing. Improving the performance of machinery thus reducing down time , increasing the efficiency of operation, and lowering maintenance costs would greatly increase productivity.

The development and application of better maintenance strategies and more advanced automation methods are two means of improving machine performance.

Department of Defense DOD and equipment manufacturers. Mining operations are also often conducted in remote locations where access to spare parts and large maintenance facilities may be difficult.

When problems are detected, the vehicle monitoring system can transmit data directly to a monitoring station at a large repair facility where the problem can be diagnosed, and repair packages can be prepared and shipped to the field before the equipment actually fails. Additional research into sensors, software, and communications could focus on adapting this concept to a variety of mining situations. Leveraging ongoing DOD programs could have substantial payoffs in terms of reduced down time, reduced volume of spare parts stored on site, and lower repair costs.

Better automation and control systems for mining equipment could also lead to large gains in productivity. Some equipment manufacturers are already incorporating human-assisted control systems in newer equipment, and improvements in man-machine interfaces are being made.

Additional research should focus on alternatives, however, such as more autonomous vehicles that have both sensor capability and sufficient processing power to accomplish fairly complex tasks without human intervention. Tasks include haulage and mining in areas that are too dangerous for human miners.

A good example of this technology is currently being used in large construction cranes; the motion of the crane to move a load from one location to another is controlled by the operator through a computer, which controls the rate of movement of the crane in such a way as to minimize the swing of the load. This technology has considerably improved safety, speeded up cycle time, and enhanced energy conservation in the motion of the crane.

Substantial research and development opportunities could be explored in support of both surface and underground mining. The entire mining system, including rock fracturing, material handling, ground support, equipment utilization, and maintenance, would benefit from research and development in four key areas:.

The above four areas represent a very broad summary of technology advances that would greatly enhance productivity and safety in mining.

A more detailed breakdown is provided in Table In-situ leaching is a type of in-situ mining in which metals or minerals are leached from rocks by aqueous solutions, a hydrometallurgical process American Geological Institute, In-situ leaching has been successfully used to extract uranium from permeable sandstones in Texas, Wyoming, and Nebraska, and in-situ leaching of copper has been successfully demonstrated in underground copper mines in Arizona, where prior mining has created sufficient permeability for leaching solutions lixiviants to contact ore minerals Bartlett, , ; Coyne and Hiskey, ; Schlitt and Hiskey, ; Schlitt and Shock, As used in this report the term in-situ mining includes variations that involve some physical extraction.

In-situ leaching involves the injection of a lixiviant, such as bicarbonate-rich, oxidizing water with added gaseous oxygen or hydrogen peroxide in the case of uranium, into the ground to dissolve the metal. The metal is then recovered from the solution pumped to surface-treatment facilities. In-situ leaching technologies are based on geology, geochemistry, solution chemistry, process engineering, chemical engineering, hydrology, rock mechanics and rubblization, and petroleum engineering Wadsworth, Related extraction techniques, herein lumped into the broad category of in-situ mining, include: 1 extraction of water-soluble salts e.

In-situ leaching has many environmental advantages over conventional mining because it generates less waste material and causes less surface disturbance no mill tailings, overburden removal, or waste-rock piles. The major environmental concern is postmining water quality. For example, in the case of uranium, concentrations of uranium and its associated radioactive daughter products and, in some cases, potentially toxic elements, such as arsenic and selenium, could be elevated.

Site reclamation has been successful at several south Texas sites where in-situ leaching of uranium was first undertaken in the s. In-situ uranium leaching also has advantages in terms of health and safety because the leaching process selectively removes uranium and leaves most of the dangerous radioactive daughter products in the. In addition, little heavy machinery is required to remove the large volumes of rock that would have been processed in a conventional mining operation.

With in-situ leaching low-grade uranium deposits with approximately 0. In-situ leaching of uranium typically involves the development of a well field with five-spot injection and production wells Figure , four production wells on the corners of a square, and one injection well in the center. Monitor wells, used to monitor fluid flow and containment, are distributed around the periphery of the injection-production well field.

Because development of the mine depends heavily on drilling and completion of the well field, improvements in drilling efficiencies faster and cheaper drilling would clearly increase the productivity of in-situ mining. With directional drilling, particularly when coupled with sensors on or near the drill bits and controls on water pressures along the length of horizontal segments of holes, lixiviants could be placed more directly in contact with ores in the middle of the ore bodies.

In-situ leaching of uranium is currently limited to low-grade deposits in highly permeable hundreds to thousands of millidarcies , essentially horizontal sandstones.

Well completions are similar to water wells, with casings perforated in the permeable, ore-bearing aquifers. The use of polyvinyl chloride casing, which is considerably cheaper than steel or stainless steel casing, currently limits depths of economical drilling to within meters of the surface Dennis Stover, vice president, engineering and project development, Rio Algom Mining Corporation, personal communication, June 14, The development of inexpensive casing that could withstand higher pressures would expand the resource base to include known deposits at greater depths.

Noninvasive techniques techniques that do not require drilling holes into the ground that detect hydrologic inhomogeneities, such as clay lenses that are barriers to fluid flow in sandstones and that determine hydrologic properties transmissivity, permeability would greatly improve hydrogeologic modeling and well-field design. Cross-borehole tomography e. Increased computational speed and greater storage capacity would also improve hydrogeological modeling.

Well-field operations can be further improved with the development of in-stream chemical sensors for the major constituents lixiviants, elements being mined, and elements of environmental concern, such as arsenic, selenium, molybdenum, and vanadium in the case of sandstone uranium deposits.

Thus far in-situ leaching in pristine formations where the rock matrix has not been modified prior to leaching has been economically successful only in the highly permeable. The drawing shows the locations of wells used to inject lixivants, wells from which uranium-rich solution is pumped production wells , and wells used to monitor fluid flow and containment. Although lixiviants are available to leach various copper oxide and copper sulfide minerals, attempts at in-situ leaching of copper in pristine formations have not been very successful because the lixiviants have not been able to adequately contact the ore minerals in the rock.

At the San Manuel in-situ operation in Arizona, recovery rates from caved areas already mined have been on the order of only 50 percent over five years Sharon Young, consultant, Versitech, Inc. The most successful in-situ copper leaching has been in ore bodies that had been previously mined; after the high-grade ores were removed open stopes remained with rubble of lower grade wall rock that could be contacted by lixiviants.

New technologies for the in-situ fracturing or rubblization of rocks could be extremely beneficial. Increasing permeability in the rocks to allow lixiviants to contact ore minerals is the biggest challenge for the in-situ leaching of metals.

One promising approach to increasing permeability, as has been done for copper, is to rubblize rock during conventional mining, thereby taking advantage of the open spaces already created.

Lixiviants are available for leaching not only uranium and copper but also gold, lead, and manganese, to name a few. Nevertheless, cheaper, faster reacting lixiviants would increase production and could also increase the number of metals that could be considered for in-situ leaching.

At the same time, lixiviants that suppress the dissolution of undesirable elements, such as arsenic and selenium, which have geochemistries that are significantly different from uranium, would be helpful, as would additives that lower concentrations of those elements during reclamation.

Better thermodynamic and kinetic data on important solid phases and aqueous species would facilitate the search for better lixiviants and additives to promote the precipitation or adsorption of undesirable elements. Confinement of lixiviants and mobilized metals to the mining area is another major challenge. Bore-hole mining has much the same appeal as in-situ leaching because it also tends to minimize the surface footprint of the operation.

The biggest challenge for bore-hole mining is the development of tools that can break or cut and remove rock tens of meters beyond the well bores. Various technologies can be envisioned for accomplishing this task; some, such as flexible cutters that can move out from the bore hole in various directions, may require the development of other tools, such as sensors that can distinguish ore from waste rock.

Many areas offer opportunities for research and technology development in in-situ mining and related approaches to direct extraction Table The chief hurdle to using in-situ leaching for mining more types of mineral deposits is permeability of the ore.

The uranium deposits for which in-situ leaching has been successful were located. However, ore minerals in the most permeable parts of rock formations are unusual; many metallic ores and industrial-mineral deposits are not highly permeable. Technologies that could fracture and rubblize ore in such a way that fluids would preferentially flow through the orebody and dissolve ore-bearing minerals although this would be difficult in competent rocks with high compressive strengths are, therefore, a high priority need for in-situ mining.

For some commodities, such as phosphate rock and coal, removal through bore-hole mining of the entire rock mass without dissolving specific minerals may be an alternate approach.

New technologies that would extend rock fracturing and cutting to tens of meters beyond well bores, while maintaining control of the direction of cutting to stay within the orebody or coal seam and avoid removing waste rock, would make bore-hole mining more attractive. Key environmental and health concerns raised by in-situ leaching are the possibility of potentially toxic elements being brought to the surface or mobilized into groundwater.

For example, selenium, arsenic, molybdenum, and radioactive daughter products of uranium are concerns in mining sandstone-type uranium deposits. Therefore, the committee also rates as a high priority development of lixiviants and microbiological agents that can selectively dissolve the desired elements and leave the undesired elements in the rock. The closure of in-situ leaching facilities raises an additional environmental concern, especially in the copper industry where large-scale in-situ leaching of oxide ore bodies.

During operations the maintenance of a cone of depression around these ore bodies and the continuous extraction of product solution limits the release of lixiviants and mobilized metals to the surrounding aquifer.

However, once mine dewatering and solution recovery are completed, there may be a significant potential for the transport of metals and residual leaching solution. To the extent that the orebody is again totally immersed in the water zone, metals will be in a reduced state, and their mobility will be limited. However, if leaching has taken place above the water table, metals may continue to leach if meteoric water penetration and bacterial activity are sufficient to produce acid conditions.

Research should, therefore, also include the evaluation of how these facilities can be closed without long-term adverse impacts to ground-water quality.

Mineral and coal processing encompasses unit processes required to size, separate, and process minerals for eventual use. Unit processes include comminution crushing and grinding , sizing screening or classifying , separation physical or chemical , dewatering thickening, filtration, or drying , and hydrometallurgical or chemical processing. Pyrometallurgical processing smelting of mineral concentrates is not discussed in this report.

Coal processing, mainly for reducing ash and sulfur contents in the mined raw coal, requires a subset of processing technologies. Some problems in coal processing arise from the way the sulfur and ash are bonded and the need to keep the water content in the cleaned coal low. Different unit processes described in this section are required in specific cases; some processes are designed especially for the treatment of a particular mineral commodity.

Therefore, the committee established a technical framework and broad economic principles as a basis for recommending categories of research and development. The key environmental, health, and safety risks and benefits of these technologies are also highlighted.

Comminution, an energy-intensive process, usually begins with blasting of rock in the mining operation followed by crushing in large, heavy machines, often used in stages and in combination with screens to minimize production of particles too fine for subsequent treatment Sidebar Grinding is usually done in tumbling mills, wet or dry, with as little production of fine particles as possible.

Comminution is a mature process for which few changes have been made in the past decade. Dry grinding, a higher cost process than wet grinding, is used mainly for downstream processing that requires a dry ground material or for producing a special dry product. The manner in which rock is blasted in mining operations subjects the rock mass to stress resulting in breakage.

Different blasting methods result in different stress distributions in the rock and may have a significant effect on subsequent comminution operations Chi et al. The effects of blasting on crushing and grinding are poorly understood. Comminution may take advantage of internal cracking and weakness in the rock caused by an explosive shock from blasting. However, quantifying this phenomenon will require a multidisciplinary investigation involving the physics of rock breakage, mining and mineral processing, and the optimization of energy requirements between blasting and crushing for size reduction.

In the metals and coal industries comminution is generally done to liberate the mineral. In the industrial-mineral sector grinding is more commonly used to meet product specifications or for economic reasons. For example, wet-ground mica commands a much higher price than dry-ground mica of the same quality and size. The grinding method after mineral separation must ensure that the final products. Before a mine is established a long process of metal and mineral exploration is required.

Once this preliminary investigation has been carried out, more and larger rock samples are drilled and sent to a laboratory for testing. Very few rock samples contain metals or mineral of a high enough grade quality to be worth mining. Each exploratory step is based on the information available at that time. Money and effort are spent to raise the degree of confidence in the measurement of the shape, size quantity and grade of the mineralisation held in the Earth's crust.

When a company decides that a mining operation is feasible, a social and environmental impact assessment is undertaken and submitted to the relevant environmental regulatory authorities for approval. This important process should include provisions for public hearings and submissions. It takes one to three years. A feasibility study is also concerned with mine closure, ie what happens to the mine when there is no more economically-mineable ore to extract. A feasibility study typically takes from one to three years, but it can be longer.

It depends on the need to test at small- and large-scale the planned mining and processing technologies, and the nature of the mine being built, ie whether it is a brownfield project an extension to an existing mine or a greenfield project a new mineral deposit.

In total, the start-up phase for a mine from exploration to first mine production may take more than ten years. Surface mining involves the stripping removal of surface vegetation, soil and if necessary layers of bedrock to reach buried ore deposits. Common techniques for surface mining include:. By contrast, subsurface mining requires mining a vertical shaft into the ground, from which lateral tunnels are excavated at different depths to reach the ore body.

Beneficiation: Processes that separate the desired mineral from the rest of the rocks and minerals in the ore. Electroplating: A process that uses an electrical current to encourage precipitation of the desired element. Flotation: The beneficiation process in which bubbles of a reagent attract the desired mineral from the slurry and rise with it to the top of the mixture. This froth can then be removed for further concentration.

Leaching in mining : The use of chemicals such as sulfuric acid or sodium cyanide to dissolve the desired metals and transport them in solution to a collection area. Milling: The physical process of crushing and grinding the ore within the beneficiation process. Ore: A material that occurs naturally and that contains a mineral s that can be extracted for a profit.

Ore Grade: The concentration of the desired metal or element within the ore. Reclamation: The restoration of land to either natural conditions or another useful purpose; this often involves the process of stabilizing soils and slopes in an area through the grading of slopes and use of vegetation. Refining: The final process in purifying an ore to the desired concentration after previous beneficiation.

A refinery is where this process happens. Remediation: The process of fixing, removing, or counteracting an environmental problem. Slurry: A mixture of water and fine particulate material. Smelting: The process of melting the beneficiated ore concentrate to reduce the impurities and concentrate the desired element. Superfund: The program established to address hazardous waste sites with no owners. It enables the Environmental Protection Agency EPA to fund and perform clean-ups as well as locate the responsible party if still in existence.

Tailings: Waste material created from the beneficiation process. Waste Rock: Rock that must be moved in order to obtain the ore. This rock does not have a high enough concentration of the desired mineral to make it economically or technologically viable to extract.

Hudson, T. Global Acid Rock Drainage Guide. Hentschel, T. Pipken, B. Geology and the Environment. Salamon, M. We encourage the reuse and dissemination of the material on this site for noncommercial purposes as long as attribution to the original material on the InTeGrate site is retained. Material on this page is offered under a Creative Commons license unless otherwise noted below. Show terms of use for text on this page ».

Show terms of use for media on this page ». Disclaimer: Any opinions, findings, conclusions or recommendations expressed in this website are those of the author s and do not necessarily reflect the views of the National Science Foundation. Your Account. Learn More. These materials are part of a collection of classroom-tested modules and courses developed by InTeGrate. The materials engage students in understanding the earth system as it intertwines with key societal issues.

The collection is freely available and ready to be adapted by undergraduate educators across a range of courses including: general education or majors courses in Earth-focused disciplines such as geoscience or environmental science, social science, engineering, and other sciences, as well as courses for interdisciplinary programs. Explore the Collection ». The student materials are available for offline viewing below.

Downloadable versions of the instructor materials are available from this location on the instructor materials pages. If you would like your students to have access to the student materials, we suggest you either point them at the Student Version which omits the framing pages with information designed for faculty and this box. Or you can download these pages in several formats that you can include in your course website or local Learning Managment System.

Learn more about using, modifying, and sharing InTeGrate teaching materials. Identify a mining company's goals with each of the following: exploration, extraction, concentration, reclamation, and remediation. Describe how wastes are created during the different stages of product creation and use. Summarize the effects of mining on land use and what can be done to minimize negative effects. Identify how air, water, and land can potentially be polluted by mining and associated activities.

Give examples of how mining, beneficiation, etc. In this reading: Introduction Exploration Extraction Concentration Cleaning Up Afterwards Environmental and Societal Concerns Glossary Other Information and Sources Introduction Most of the mineral resources that we use in our daily lives are not easily found and do not come out of the ground in a useable form. Exploration Estimates of the amounts of elements in the Earth's crust represent averages over the entire crust and seldom reflect the composition at a particular location.

During the exploration process, a mining company seeks an area where the desired mineral resource is concentrated and attempts to determine the size of the ore body and the mineral resource's ore grade. Higher ore grades higher concentrations make the mining project more viable see Table 1. However, there are many other factors that can influence the decision to extract ore from a specific area. Click here to see where the deposit might be.

Click here to see another way the deposit might be oriented. Provenance: Table by Leah Joseph. Show Sources and Other Information. Latimer, Cole.