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By Michael J. Miller

In the design of a modem mill, a stockpile storage system for raw and/or semi-processed ore has become almost indispensable. This paper discusses the benefits of such stockpile storage as well as the various types of belt conveyor stockpiling units available. Particular attention is given to large radial stackers since they offer the greatest flexibility. Stacker control systems and accessory equipment are briefly discussed. Various alternative reclaiming arrangements for stockpiles are reviewed and a discussion of the advantages and drawbacks of each arrangement is included.

Jan 1, 1979

By Iain Weir-Jones

The efficient operation of an open pit mine presupposes that the slopes are maintained at an angle which closely approaches that of the ultimate stability of the slope. In order to do this in a safe manner, it is essential that the data relating to the behavior of the slopes be monitored and made available, through an instrumentation system, to the appropriate personnel so that soundly-based engineering decisions may be reached with the minimum of wasted effort. In addition to simply detecting potential failures, the system should also define what type of failure is developing; i.e., rotational, wedge, or dilational failures. Providing this data is the prime function of a stability monitoring system. Therefore, in an operating open pit mine, the instrumentation system must provide information which will have a direct bearing upon both the safety and the economics of the operation, as well as provide data which is pertinent to initial design, or to the re-design of slopes where developing instability is found to be a problem.6 It is possible to excavate pit slopes which will remain stable under extremely adverse conditions; however, such slopes would usually be so flat that they would tend to render the operation of a pit uneconomical which might otherwise be mined at a profit. On this basis, all practical pit slopes must be considered to be, to some ex- tent, unstable; if they are not, the design is too conservative and the mine is not returning its maximum profit. To reduce the problem to its fundamentals, one can simply state that the ideal pit slope design produces a slope which stands with zero maintenance for the entire life of the pit and then collapses into the final excavation as soon as the personnel and equipment have been removed. Such a design is impossible to achieve, but the fact remains that an efficient slope would hover on the edge of failure for the life of I the pit. As one retreats from this position, the profitability of the mine decreases because of an unduly conservative design.

Jan 1, 1975

By R. P. King

Knowledge of the behaviour of flotation machines had developed and increased considerably over the last few years. Although much work remains to be done on the study of the fundamental processes that influence the collection of hydrophobic particles at an air-water interface, there is enough information to permit the building of realistic models of the gross flotation behaviour of various ores. These models serve as an ideal base for the development of simulation techniques for the steady-state behaviour of entire flotation plants that consist of a large number of individual flotation machines. Simulation techniques have a very real role to play in assisting with the design of new plants and in improving the operation of exisiting plants. Recently, highly efficient data-logging systems have been introduced on flotation plants. These systems are based on the on-line measurement of volumetric flowrate, pulp densities, and metal contents, and they generate enormous quantities of information regarding the operation of the plant. Unfortunately, this information is largely wasted at the present time because efficient data-reduction techniques, although available10 are not in common use. Simulation techniques play a central role in such data reduction because they form the essential link between the fundamental kinetic flotation processes on the one hand and the plant data on the other.

Jan 1, 1974

By Carl G. Hogberg

To the casual observer there is probably no simpler appearing operation in the mineral industry than a limestone quarry. It might seem that the entire operation - from the drilling, blasting, and loading of the stone, its transport to a mill for crushing, washing and sizing, to loading into boats, railroad cars, or trucks for delivery to customers - can be comprehended at a glance. But no first impression could be more misleading. It is one of the purposes of this presentation to sketch the broad outlines of the extensive limestone industry in the United States which, measured in terms of volume of production since the end of World War II, has grown almost 300 per cent to a national level in 1957 of 384 million net tons.1 Another objective will be to discuss in more detail this industry in the State of Michigan. For this latter purpose, the Michigan Limestone Division plants at Calcite and at Cedarville will be used as examples. These descriptions will, we believe, show that the limestone business has complexities to match its size.

Jan 1, 1962

By Christine E. Turner-Peterson

Pore-filling organic material concentrated uranium to form sandstone-hosted primary uranium deposits in the Jurassic Morrison Formation of the Grants uranium region, New Mexico. Petrographic observations and radiometric ages for primary ore in the Westwater Canyon Member require that the organic material was emplaced early in the diagenetic history of the host sandstone; in fact, organic material was emplaced before major compaction. This inferred early emplacement constrains models concerning the nature and origin of the organic material and thus also constrains models of ore genesis. Reconstruction of the burial history of the basin indicates that Late Jurassic-Early Cretaceous time, the interval of inferred emplacement of the organic material, was probably not a time of hydrocarbon generation and migration. Nuclear magnetic resonance analyses, elemental abundances, and isotopic studies provide further constraints on the nature of the organic material, and data from these studies are consistent with a humic acid rather than an oil origin. In addition, the overall tabular shape of primary uranium orebodies and the way these orebodies are suspended in the host sandstone mimics Recent deposits of humate, the precipitated form of humic acids. The critical clue that favors a humic acid origin for ore-related organic material is provided by the nature and patterns of postdepositional alterations that are spatially and temporally related to primary ore, specifically destruction of detrital magnetite and ilmenite (iron-titanium oxide) grains. Humic acids are implicated in the destruction of iron-titanium oxide grains because these organic acids are one of the most effective natural agents in leaching of Iron from these grains. Thus, timing constraints, chemical evidence, orebody geometry, and the nature and patterns of ore-related alterations favor a humic acid origin and suggest that an oil origin is highly unlikely. Because alteration of iron-titanium oxide grains tracks the pathways of humic-bearing solutions through the host sandstones, it is possible to trace these solutions back to their source. Alteration patterns in the Westwater Canyon Member suggest that the humic-bearing solutions originated as pore fluids in the mudflat facies of the overlying Brushy Basin Member and moved into adjacent sandstones during early dewatering of the mudstones. The humic acids precipitated, by the process of cation loading, in tabular layers. Uranium was concentrated within these tabular layers by complexation with the humic acids to form primary uranium orebodies.

Jan 1, 2013

By Ray A. Rothrock

The in situ mining of uranium is the process whereby chemical lixiviant is injected by means of wells into, and flowed through, an ore body. The lixiviant reacts with uranium which has been previously oxidized making the uranium soluble. The solution is then brought to the surface by means of producing wells. In situ mining disturbs the ground-water quality in the immediate area. Since ground water is a natural resource used by man, care must be taken not to allow the lixiviant to escape the local mining area. Also, when the ore body is mined out, the area should be restored to as near its original state as is reasonably achievable. The return of ground-water quality to its original state can occur naturally over a long period of time or be enhanced using appropriate technological means.

Jan 1, 1981

By James E. Lawver

Part I describes the general geology of the Florida deposits. As the lucrative Bone Valley Formation is depleted, replacement production will move progressively into areas of total Hawthorn production. The reserves of the immediate future are a mixture of two distinct ore types referred to as the upper (high grade) zone and the lower (low grade) zone. The upper zone is somewhat similar to the Bone Valley Formation that has been Florida's source of production for the past 100 years and will respond favorably to present beneficiation practices. By contrast, the lower zone ore contains significant quantities of dolomite that must be removed in order to produce an acceptable grade pebble or flotation sized product. Part II reviews past practice and describes future trends in mining and ore transportation. This presentation (Part III) is confined to the problems of beneficiation, waste disposal, and environmental regulation.

Jan 1, 1983

By B. A. Hillman

Silicon is the second most abundant element on earth, exceeded only by oxygen. Silicon dioxide forms a crystalline structure of repeating SiO2 molecules which form characteristically hard, durable crystals. As a result, crystalline silica is Ubiquitous in the crustal rocks, sediments and the mineral products derived from mining. An examination of the history of studies that identify silica as a human and animal carcinogen is presented in the context of the development of a public health policy in California. The implications for the cost of conducting aggregate and other mining operations in the state are discussed.

Jan 1, 1992

By N. A. Karl, D. R. Wilburn

"This summary of international mineral exploration activities for the year 2015 draws upon information from industry sources, published literature, SNL Metals & Mining (SNL) (Charlottesville, VA) database and specialists in the U.S. Geological Survey (USGS) National Minerals Information Center. The summary provides data on exploration budgets by region and mineral commodity, identifies significant mineral discoveries and areas of mineral exploration, discusses government programs affecting the mineral exploration industry, and presents analyses of exploration activities performed by the mineral industry.Three types of information are reported and analyzed in this annual review of international exploration: budgetary statistics expressed in U.S. dollars provided by SNL; regional and site-specific exploration activities that took place in 2015 as compiled by the USGS; and regional events that affected exploration activities including economic, social and political conditions, which were derived from published sources and discussions with USGS and industry specialists. Commodity and regional compilations are presented in this summary. Because multiple sources were used to develop commodity and regional compilations, statistics may vary depending on the source and type of data that are being reported.The SNL data summarize planned company budgets for worldwide exploration activities in 2015 for 24 nonfuel mineral commodities and metal alloys and are based on company surveys. Surveys focused on precious metals (gold, platinum-group metals and silver), base metals, (cobalt, copper, lead, molybdenum, nickel, tin and zinc), bulk commodities (bauxite, chromite, iron ore, manganese, phosphate and potash), and other commodities (diamond, graphite, heavy-mineral sands, lithium, niobium, rareearth elements (REE), tantalum, tungsten and uranium).USGS data compilations and analyses are based on information provided by USGS mineral commodity and country specialists, as well as industry contacts and published trade journals. The USGS data summarize exploration site data collected for more than 80 minerals and materials, with a focus on base metals, diamond and precious metals. The USGS analyzed available information to assess the level of exploration activity in 2015 and to report trends in mineral exploration activity for the period 2005 through 2015. These analyses identify where mineral exploration is occurring by commodity and region and the intensity of activity that is taking place in each region for selected mineral commodities, and determines those factors that most affect changes in exploration activity."

May 1, 2016

By Y. J. Wang

A critical path approach is presented for the problem of mine ventilation net- works where regulators and fans are employed to control the airflow distribution which is preassigned. The problem is a classic one which arises in mine ventilation planning. By identifying the analogy between the network for controlled flow and that for CPPI, the applications of the well known CPM technique to the ventilation network problem become straight- forward. The mathematical formulation of the problem is presented and the solutions are illustrated with examples. The effect of booster fans on the total air power consumed in a ventilation network are also discussed.

Jan 1, 1981

By C. Pritchard

John Marks said in his acceptance of the Hartman Award in 2008 ? ?I guess that without the occasional complaint, your mine is probably over-ventilated? (Marks, 2008). Miners are seldom in this situation and often spend much of the time trying to find enough air to keep the operation running. With examination there are some things that can be done to make the best use of ventilation systems. Should there be surplus air, in which some of these options may result - financial and other benefits can be obtained. Some of the issues mine operators have needed to address recently are increased airflow requirements to dilute diesel particulates in metal and non-metal mines. Also, operations are faced with demands from reserves that are deeper, hotter and further away from fans and shafts, not to mention increased production demands. Mine ventilation air is a costly commodity, especially by the time it has been heated or cooled and moved to the bottom of the shaft and through the mine airways. Most of the options presented in this paper are useful for metal non-metal operations but some may be applicable to coal too. OPTIONS FOR IMPROVEMENT Some of the areas to be addressed are shop ventilation methods, auxiliary equipment areas, dedicated intakes and returns, optimizing development, examination of mine airway utilization and alternative ventilation methods. UNDERGROUND SHOPS First, examine what is being done with the underground shop air. If it is being coursed directly to the returns there may be some potential to better utilize this, in most cases, relatively contaminant free air. Research the legal options for ventilating mine shops. MSHA regulations in 30CFR 57.4761 (1) allow the following options: To confine or prevent the spread of toxic gases from a fire originating in an underground shop where maintenance work is routinely done on mobile equipment, one of the following measures shall be taken: use of control doors or bulkheads, routing of the mine shop air directly to an exhaust system, reversal of mechanical ventilation, or use of an automatic fire suppression system in conjunction with an alternate escape route. The alternative used shall at all times provide at least the same degree of safety as control doors or bulkheads. Discussion This regulation gives some operators flexibility in ventilating underground shop facilities. If shop air is to be coursed through the work area, and then directly to the mine return, the question should be asked ? is the quality of air good enough to be reused in the mine, and if so, what are the risks? Can the risks be accommodated and managed to accomplish the change? If so, a considerable increase in mine level airflow could be attained by reusing shop air. Clearly, regulations are a minimum standard, and can be exceeded. Metal non-metal mine regulations are not as specific as coal due to the multitude of different mining methods and conditions utilized. Risks must be thoroughly examined and addressed to assure a safe environment. Issues Determine what contaminants are being produced in the work area ? welding fumes, diesel exhaust, paint fumes, chemicals and solvents, etc. Survey the area and determine exposures. MSHA requires exposure monitoring in 30 CFR 57.5002 (1) of dust, gasses mists and fumes to assure air quality is being met. Perform surveys and examine existing data to quantify personal and area concentrations of contaminants. Often there is adequate circulation such that exposure levels in shop work areas are low. After sending shop air back into the system any contaminants would be further lowered by dilution with other mine intake air downstream. Look at the shop work schedule. If only on day shift, the other two shifts and possibly weekends have no activity or source of contamination to affect the ventilation system. The worst case planning scenario would be a shop fire. Study and simulate how this would affect the mine and shop area. MSHA regulations require an escape route and a fire suppression system be installed and maintained as follows in 30 CFR 57.4671 (1): (d) Automatic fire suppression system and escape route. If used as an alternative, the automatic fire suppression system and alternate escape route shall meet the following requirements: (1) The suppression system shall be? (d)(1)(i) Located in the shop area; (d)(1)(ii) The appropriate size and type for the particular fire hazards involved; and (d)(1)(iii) Inspected at weekly intervals and properly maintained. (2) The escape route shall bypass the shop area so that the route will not be affected by a fire in the shop area. Case Study In an underground room and pillar mine, active mine workings were advancing further away from the mine shaft with deteriorated returns and leakage having a negative effect on ventilation airflows to the face. Mine level airflows were 236 m3/s (500,000 cfm) and shop airflows were 24 m3/s (50,000 cfm) (see Figure 1A). No additional capacity was available at the main surface fan. A solution was to utilize the shop air then send it to the mine areas instead of directly to the return. Considerable information on shop air quality and exposures from many years of operation was examined and no negative data was discovered. A risk analysis determined that moving forward with a shop air reuse program was desirable. A plan was developed, analyzed and decision to proceed approved by mine management. The change was simulated on the computer with the USBM/MTU MFire program before being implemented. This included utilizing fire scenarios to examine potential exposures to inby mining sections and plan escape routes. A monitoring system was designed and installed in cooperation with the US Bureau of Mines to monitor carbon monoxide

Jan 1, 2009

By Harry Perry

Although the markets for coal in the United States have changed rapidly over the last three decades, the uses of coal, namely, to produce heat and power or coke have been left almost unchanged. The coke is used either as a chemical reducing agent alone or as a reducing agent and source of heat. Most of the heat and power markets for coal require no coal processing, although for more than 50 years, many proposals to skim the more valuable substances in coal before burning have been advanced. Thus, the only large tonnage market requiring processing of coal is high-temperature carbonization to make coke. At present, coal requires processing for some small markets, but for future potential large markets, such as gasification, conversion to liquid and gaseous fuels, and conversion to chemicals, coals will require more processing than is now being done.

Jan 1, 1962

The Colorado portion of the Rio Grande rift is clearly defined physiographically from the south in the San Luis valley northward to the latitude of Leadville where sediments of the Dry Union Formation (Tweto, 1961) accumulated within the subsiding rift zone. To the north of Leadville is a system of faults active in the late Tertiary, including the Mosquito fault that offset a portion of the Climax mineralization (Wallace et al., 1968). Tweto (197B) describes remnants of Dry Union Formation against the Mosquito fault north of Dillon in the Blue River valley, so it is apparent that the rift and associated sediments extended well to the north of Leadville. Kelley (1952, 1954, 1956) and Chapin (1971) have noted in New Mexico that the Rio Grande rift is a series of en echelon basins, offset to the east, with constrictions connecting them (Fig. 1). In Colorado the structural basins are offset to the west. The net effect of all the rift zone basins in New Mexico and Colorado is an arcuate pattern (Fig. 1) abutting the Colorado Plateau and Sari Juan Volcanic Province on the west. The width of the rift system gradually decreases northward to about Leadville where rift definition is not apparent.

Jan 1, 1987

By I. Iwasaki

A low-grade copper-nickel deposit, with an estimated size of 4.6 billion tonnes and with average analyses of 0.6% copper, 0.2% nickel, occurs in northeastern Minnesota. In addition to copper, nickel, cobalt, and precious metals, the Duluth gabbro contains magnetite, ilmenite, olivine, plagioclase and biotite. It is estimated that the flotation tailings that would be produced by a concentrator of optimal size to sustain a smelter would amount to 20 million t per year. The flotation tailings, having already been ground, warrant a closer examination for the recovery and utilization of potential by-products. The residual sulfide minerals and fibrous minerals may also be isolated and treated separately for useful purposes or for disposal in an environmentally acceptable manner. Two flowsheets were developed; one involving preconcentration by low- and high-intensity magnetic separation and another involving preconcentration by gravity concentration. The concentration methods for recovering and purifying individual by-product minerals were investigated. From their chemical, physical and mineralogical characteristics, the potential areas of application and marketabilities of each product fraction were surveyed.

Jan 1, 1983

By Charles Banks Belt

In 1925, Niggli (1925, pp, 1-69), formulated a physico-chemical, explanation for the origin of hydrothermal ore deposits, from a concept that had appeared earlier in the literature in the writings of Von Groddeck, Stelzner, Beck, de Launay, Kemp, and Lindgren. Niggli proposed that pressure at depth could force volatiles from deep-seated magmas. The volatiles would In turn form pegmatites and then ore deposits as the fluids cooled. This is one view of a general theory of ore genesis that gained secondancy for years among such prominent geologists as Fenner (1926, p, 697) and Emmons (1936, pp. 29-70). It was, proposed that ore deposits were precipitated from solutions or fluids that had escaped or been separated from a deep-seated magma by means of liquid immiscibility or crystallization or gas transfer. This theory is based on the presence of igneous rocks close in space and age to hydrothermal ore deposits in many mining districts of the world. As is well known, there are many ore deposits apparently of hydrothermal origin that are neither spatially nor chronologically related to igneous rocks, In still other localities where there are no hydrothermal ore deposits, igneous rocks occur that are similar in composition to those in mining districts. In view of such facts, the applicability of the Niggli theory to all hydrothermal ore deposits may well be questioned. The chief purpose of this paper is to test the Niggli theory by studying the primary petrology, hydrothermal alteration, and distribution of copper and zinc in silicic igneous plutons supposedly genetically related (in the Niggli sense) to nearby hydrothermal ore deposits, Silicic Tertiary plutons in three New Mexico mining districts were chosen, the Hanover-Fierro intrusive at Hanover and Fierro, the Granite Mountain pluton at Magdalena, and the four outliers of the Lordsburg stock at Lordsburg. First, it had to be established whether the observed plutons were or were not the source of the adjacent ore deposits. This was done by studying the relation between the copper or zinc distribution-and the primary or secondary features in the plutons studied, and the time relations between instrusion and ore deposition. Primary igneous features of a pluton are defined as the minerals, texture, shape, and character of the pluton which were formed prior to the complete solidification of the rock, secondary features include all changes that took place in a pluton after solidification. They are identified by their cross cutting nature or as replacing primary minerals, Under the Niggli concept, it is proved that the ore ions did not originate from the parts of the pluton now visible as immediately adjacent to the ore deposits; it must then be established, if possible', that the ore ions were separated from deeper parts of the intrusive, Some idea as to whether the copper or zinc ions originated from a related magma at depth may be gained by a comparison between the primary (that is, pre-alteration) zinc and copper abundances found in ore localizing intrusive studied and the average abundances for copper and zinc in silicic igneous rocks most recently given in the literature. Finally, the relation between ore deposition and hydrothermal alteration was studied on a regional as well as on a local scale.

Jan 1, 1958

By William E. Saegart

Copper has been mined in the Philippines since at least as early as the Ming dynasty (1368 A.D. to 1644 A. D.). The principal source areas of this early production were in Camarines Norte (Paracale), in the Mountain Province, which now boasts the largest number of Philippine porphyry copper deposits, in Masbate and in Surigao, The Spanish Era began in 1521. Although they were primarily interested in gold, the Spaniards operated several copper mines including the San Remigio mine on Panay and the Lepanto mine in northern Luzon, beginning in 1842 and 1865 respectively. Prior to World War II most of the Philippine copper production was supplied by these same two mines together with the Hixbar mine, Rapu Rapu Island which began operation in 1939. The Hixbar and San Remigio mines are cupriferous pyrite deposits and the Lepanto is a vein-¬form replacement deposit (Kinkel et al. ,I 1956). No significant copper production was derived from porphyry copper occurrences prior to world War II.

Jan 1, 1976

By David L. Veith

As the basis for the State of Minnesota's Regional Copper-Nickel Study environmental evaluation, hypothetical mine models were developed ranging in ore capacity from 5.35 to 20.00 x 106 mtpy. Open pit and underground mining operations were defined utilizing conventional methods of ore extraction. Processing of the copper-nickel sulfide material involved conventional bulk flotation of the valuable minerals, with maximum water recycle And tailing disposal. Flash smelting and electrolytic refining of the concentrate resulted in 0.10 x 106 mtpy copper plus nickel metal, plus associated cobalt and precious metals. Variations in model parameters allowed environmental trade-offs to be identified.

Jan 1, 1980

By Frank J. Foster

This Paper will deal with Bucketwheel Suction Dredging and its particular relationship to mining applications. There will be comparisons with other methods of suction dredging and descriptions of two recent bucketwheel installations in the mining area. The Directory of World Dredging Fleets published in the `larch 1984 edition of World Dredging magazine shows that there are about 1.000 conventional Cutterhead Dredges listed throughout the world with 289 in the United States. There are 242 Bucketline Dredges listed throughout the world of which only 6 are in the United States. These figures are not completely accurate because several units are known to the author that are not on the list and, of course, there may be others.

Jan 1, 1984

By C. O. Brawner

Approximately 7 billion tons of soil, rock and ore are currently being excavated in open pit mines and quarries on the North American continent at the present time. As the depth of excavation increases and the grade of ore being mined reduces, the safety and economy of the stability of the pit slopes becomes increasingly important. The magnitude of the potential influence on economics can be appreciated from the results of recent full scale field studies by Kennecott Copper Corporation at the Kimbley pit near Ely Nevada (Merrill, 1968). This pit was originally excavated with an average wall slope of 45°. Based on detailed studies it appeared that a slope of 610 would be stable. Subsequent excavation to this slope proved the original pit could have been steepened by 16° during production.

Jan 1, 1968

By Patrick Scott, Germán Schmeda, Morgan Mullins, Liam Knudsen, Bradley S. Van Gosen, Carma A. San Juan, Nicholas A. Karl, Jeffrey L. Mauk, Clayton Forbush

The objective of the US Geological Survey’s mineral deposit database project (USMIN) is to develop a comprehensive twentyfirst century geospatial database that is the authoritative source of the most important mines, mineral deposits, and mineral districts of the US. Since May 2017, the project has focused on critical minerals. Data for critical minerals that are produced as products are relatively robust, whereas data for critical minerals that may be recovered as byproducts are commonly of much poorer quality. Similarly, more is known about critical minerals that occur in conventional deposits than where those critical minerals occur in unconventional deposits. For example, rare earth elements occur principally in deposits hosted by alkaline igneous rocks, but there is potential for their production from phosphate rock mining, which is less documented. Lithium (Li) has been recovered from pegmatites and brines, but other Li-bearing deposit types have been delineated that may go into production. Cobalt may be produced as a byproduct or coproduct from a wide range ofmineral deposit types, whereas rheniumis a byproduct of copper ore. Significant opportunities for research exist that could help identify new sources of critical minerals, and may also help increase production and recovery from existing sources.

Feb 8, 2021