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3 Technologies in Exploration, Mining, and Processing
Pages 19-46

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From page 19...
... Most metallic ore deposits are formed through the interaction of an aqueous fluid and host rocks. At some point along the fluid flow pathway through the Earth's crust, the fluids encounter changes in physical or chemical conditions that cause the dissolved metals to precipitate.
From page 20...
... for trace amounts of metals or other elements that may indicate the presence of a buried ore deposit. Geochemical techniques have played a key role in the discovery of numerous mineral deposits, and they continue to be a standard method of exploration.
From page 21...
... An example of the latter is the recent development by the mining industry of a prototype airborne gravity system. Gravity measurements are a typical means of locating dense metallic mineral deposits and of mapping different rock types in the Earth's crust.
From page 22...
... The primary reasons are technological and economic. Current seismic technology is used to gather data at relatively great depths (thousands of meters below those typical of mineral deposits)
From page 23...
... Support for technological development, primarily the miniaturization of drilling technologies and analytical tools, could dramatically improve the efficiency of exploration and improve the mining process. A1though industry currently supports the development of most new geochemical and geophysical technologies, basic research on the chemistry, biology, and spectral characterization of soils could significantly benefit the mineral industry.
From page 24...
... In addition, as more easily minable deposits are depleted, mining technology and equipment and mining systems for extracting problematic deposits will have to be developed. Surface Mining Surface mining is a generic term describing several methods of mining mineral deposits from the surface, which entails removing the vegetation, top soil, and rock (called overburden materials)
From page 25...
... TECHNOLOGIES IN EXPLORATION, MINING, AND PROCESSING FIGURE 3-3 Photograph of open-pit copper mine at gingham Canyon. SOURCE: Kennecott Utah Copper Corporation.
From page 26...
... , and modern technology for planning, designing, monitoring, and controlling operations. Unclergrouncl Mining Underground mining is used when the deposit is too deep for surface mining or there is a restriction on the use of the surface land.
From page 27...
... Open slopes, room-and-pillar, and sublevel sloping methods are the most common unsupported methods; cut-and-fill sloping when the fill is often waste from the mine and mill 27 tailings is the most common method of supported underground mining (Figure 3-6~. Because of the high costs associated with supported and unsupported mining methods, open sloping with caving methods is used whenever feasible.
From page 28...
... In a 3-meter-thick coal seam the amount of coal in place in a block is 6 to 7 million tons. The basic equipment is a shearer (a cutting machine)
From page 29...
... mining industry is setting impressive records in underground and surface mine production, productivity, and health and safety in all sectors of the industry (metal, industrial minerals, and coal) , the industry still needs more effective and efficient mining technologies.
From page 30...
... 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.
From page 31...
... 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.
From page 32...
... 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)
From page 33...
... 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: 1 fracture, fragmentation, and cutting, with the goal of achieving truly continuous mining in hardrock as is done with coal.
From page 34...
... · adaptation of longwall and continuous coal mining technology to the mining of other laminar metallic and nonmetallic deposits . · continuous hardrock mining with new cutting concepts incorporated into a continuous mining system · in-situ gasification of energy resources to address technical problems and environmental issues exploration of chemical and biological mining of coal to determine basic mechanisms and develop mining-system concepts · secondary recovery methods for mining Improved Machine Performance · development of sensors, software, and communications for mining situations · new alternatives for man-machine interfaces · semiautonomous control methods, such as "fly-by-wire" systems · more autonomous vehicles that can perform complex tasks without human intervention or oversight phosphate rock in Florida, uranium-rich sandstones in Wyoming, and bituminous sands in California)
From page 35...
... 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)
From page 36...
... 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 EVOLUTIONARY AND REVOLUTIONARY TECHNOLOGIES FOR MINING TABLE 3-3 Opportunities for Research and Technology Development in In-Situ Mining In-Situ Well-Field Operations · rock-fracturing and rubblization techniquesa b · directional drillingb · more efficient drillingb casing for depths below 270 meters hydrogeologic modelingb tomography between bore holesb sensors for monitoring groundwater and operational controlsb new mining technologies for increasing permeability for in-situ leaching, particularly of base metals Bore-Hole Excavation · extending of rock fracturing or cutting to tens of meters beyond well boresb · sensors for assaying samples without removing themb Hydrometallurgical Advances · development of lixiviants and microbiological agentsa b · suppression of undesirable elements in solutions · additives that precipitate or enhance adsorption of elements of concern during restoration of groundwater qualityb · thermodynamic and kinetic datab aHigh priority.
From page 37...
... 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., 1996~.
From page 38...
... The processing of ultra-fine particles, either occurring naturally in the ore or produced during comminution, is one of the biggest problems facing the mineral industry. Ultra-fine grinding is becoming common for regrinding flotation concentrates and preparing feed for hydrometallurgical processes.
From page 39...
... Some gravity separation methods can be used to treat fine particles if there are large density differences between the desired and undesired minerals. In gold plants, for example, a number of gravity devices, old and new, are being used to recover relatively coarse gold.
From page 40...
... Electrostatic separation is a dry process in which particles falling through a high-voltage static field are diverted according to their natural charges. Electrostatic separation is not suited to extremely fine particles or to large particles whose masses overcome the electrical effect.
From page 41...
... Selective Flocculation Selective flocculation technology used for industrial minerals is based on the surface chemistry of minerals. In this process chemicals are added to a fine-particle mineral mix resulting in one mineral being flocculated and the remaining minerals being dispersed in a water slurry.
From page 42...
... , heap design and construction, and solution distribution. Bioleaching for heaps and dumps was developed by the copper mining industry and adapted to treat refractory gold.
From page 43...
... Stable emulsions and the eventual formation of "crud" are problems common to most solvent-extraction operations in the mining industry. Crud can constitute a major solvent, uranium, and copper loss to a circuit and therefore adversely affect the operating cost.
From page 44...
... Recommenclations for Processing Technologies Research and development would benefit mineral processing in the metal, coal, and industrial-mineral sectors in many ways. Every unit process comminution, physical separation, and hydrometallurgy/chemical processingcould be improved by technical input ranging from a better understanding of fundamental principles to the development of new devices and the integration of entire systems.
From page 45...
... Fine-particle technologies, from improving production methods for the ultra-fine grinding of metals to minimizing the production of fine particles in coal preparation and measuring and controlling the properties of industrial mineral fine particles would be useful. Technology needs in physical-separation processes are focused mainly on minimizing entrained water in disposable solids, devising improved magnetic and electrostatic separators, developing better ore-sorting methods, and investigating selective flocculation applications.
From page 46...
... control and management of environmental hazards and stabilization of solid wastes and aqueous effluents new corrosion/abrasion-resistant materials for chemical-processing reactors robust, effective on-stream sensors models and simulations of processing to predict and optimize processing fundamentals of high-pressure and high-temperature reactions selective, stable ion-exchange resins and polymers for metals separation membrane technologies Biotechnology · fundamental advances in understanding of micro-organism/mineral interactions, genetics related to monitoring microbial activity in processing and strain development, and nonacidic microbial leaching systems · basic research on the genetics of micro-organisms used in mineral processing to develop enumeration and identification techniques and improve microbial strains · identification of nonacidic microbial mineral-processing technologies with scale-up of the most technically and economically promising processes · bioprocessing methods for selective metal recovery and concentration


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