Mineral and Mining Engineering
Mineral engineering is that branch of ENGINEERING concerned with the application of scientific and technical knowledge to the search for and production of valuable MINERALS from naturally occurring surface, underground or below-water deposits. Mining engineering, an essential part of mineral engineering, is also concerned with the construction of civil works such as tunnels, subways, power plants and shelters and, thus, is related to both CIVIL and MECHANICAL ENGINEERING. Minerals are inorganic substances, but engineers and economists commonly include materials derived from organic matter (eg, COAL; OIL AND NATURAL GAS) in their classification. A mineral occurrence is called an ore deposit when its valuable minerals can be extracted at a profit.
History in Canada
The native people of Canada were known to have used minerals (eg, COPPER) before the arrival of Europeans. Early explorers of North America showed intense interest in the mineral potential of the New World. It was not, however, until the establishment of the GEOLOGICAL SURVEY OF CANADA (1842) that scientific principles were used to determine the extent of Canada's mineral wealth. The mid-1850s (especially the GOLD RUSH) saw the beginning of a series of major finds of economic minerals. To meet the need for qualified individuals to help exploit the newfound wealth, engineering schools were established to teach core courses in civil, mechanical and mining engineering. These included King's College, Fredericton, New Brunswick, in 1854; McGill, Montréal, in 1871; School of Practical Science, Toronto, in 1873; École polytechnique, Montréal, in 1873; Royal Military College, Kingston, in 1876; and the School of Mining and Agriculture, Queen's University, Kingston, in 1893. The Canadian Institute of Mining, Metallurgy and Petroleum (CIM) was established in 1898; its national membership exceeds 12 000. The organization has over 60 local branches across Canada.
Because Canada's economy has remained resource based, mineral and mining engineers and their colleagues who discover and exploit economic minerals (geologists, geophysicists, geochemists, and electrical, mechanical, chemical and metallurgical engineers) continue to play a vital role in Canada's economic well-being. Continual improvements in mining technology have greatly reduced the hazards for mine employees (seeMINING SAFETY AND HEALTH). Canadian advances in dealing with the logistics of mineral extraction, such as floating a prebuilt processing factory to a remote site, have extended the range of usable resources. Considerable advances have also been made in technologies for extracting the required ore from the rock in which it is embedded.
The normal sequence of mineral engineering activities includes exploration (ie, PROSPECTING), evaluation, financing, development and extraction of the ore and then separation, concentration and refining of the desired minerals, using chemical, physical, electrical and metallurgical systems. The environmentally acceptable disposal of the resultant wastes is an integral part of the process. Exploration activities may still involve the traditional individual prospector looking for surface outcrops or other ready evidence of mineral deposition. Modern mineral exploration, however, makes increasing use of highly organized and specialized REMOTE SENSING methods. The benefits of surface geological mapping can be substantially extended by the use of aerial or satellite photography. Geophysics is concerned with the detection of anomalies related to gravitational, seismic, magnetic, electromagnetic, radioactivity and electrical conductivity measurements in the earth's crust. These changes may indicate the presence of valuable underground mineral occurrences. Geochemistry is used to identify unusual concentrations of chemicals in surface soils, water and vegetation as clues to the proximity of an ore deposit.
The evaluation of mineral occurrences to determine their potential value and to establish proven, probable and possible quantities of ore requires detailed sampling from surface pits and diamond drill holes. Even after extensive drilling has outlined a potential ore body, it may be necessary to carry out bulk sampling from underground shafts, drifts, crosscuts and stopes before the true value of the deposit can be accurately calculated and MINING costs established. Pilot-plant studies may be carried out to confirm or modify mining methods and treatment systems. Because of the highly competitive nature of the mineral industries, the evaluation of relatively low-grade ore deposits is becoming increasingly rigorous. Methods for funding mineral production will depend on the level of risk and the total capital requirement for the recovery procedures involved. Normally, the establishment of a limited liability company and sale of equity shares is necessary. Alternatively, some or all of the funding may be obtained through loans guaranteed by the ore proven in the evaluation stage.
Some mineral resources (eg, PETROLEUM) may be extracted from the earth via drilled holes, using induced pressure and solvents. Dredging is used to mine unconsolidated materials from below the water. Recovery of mineral nodules from the deep-sea bed requires further development of the dredging method (seeOCEAN MINING). Minerals may also be leached from surface or underground deposits by circulating solvents or microbial fluid, with later precipitation or other suitable disposal of the leached material. Surface and underground deposits may be exploited by open-pit or underground mining methods.
The development phase of mining activity involves mining engineers in complex decisions on rate of ore extraction, methods of mining and treatment of broken ore. A critical path schedule is established and, based on this schedule, equipment is purchased and a work force mobilized. Because many of these decisions interrelate, the mine planner will be involved in selection of equipment for drilling, blasting, waste control, transportation, pumping, power supply, ventilation, ground support and personnel safety. Final mining and process plant design and erection, housing and all the other complex infrastructure needs will depend on mine location and transport facilities available.
Most mining operations require some form of further processing of broken ore. This processing could be as simple as crushing and washing or may include further steps (eg, grinding, screening, flotation, gravity separation, cyanidation, leaching, precipitation, filtering, roasting), the ultimate purpose being to separate waste from valuable material and to concentrate the latter to meet customer requirements or to prepare for further processing, including smelting and electrical refining (seeMETALLURGY).
Environmental considerations require that great attention be given to the disposal of waste products. Atmospheric emissions should be treated to remove unacceptable chemical constituents and solid particulate matter. Processed water should be recycled through the ore-treatment system and, when discharged, should be treated to avoid undesirable constituents reaching rivers or streams. Suspended solids are filtered or settled in restricted basins. When an ore body is completely mined, the site should be returned to an environmentally acceptable condition; eg, plant equipment is removed and access to underground workings sealed, building foundations are normally destroyed and buried, and waste dumps are levelled and contoured to fit in with adjacent topography and seeded or planted.