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By M. A. Klugman

[This paper represents a portion of a lager study, concerning dispersion patterns of major, minor and trace elements in wall-rock about ore-bodies in part of the Colorado Mineral Belt. This phase of the work pertains to the Mg/Ca ratio variations in wall-rock adjacent to ore-bodies in two mines of the Alma-Horseshoe Mining District of Central Colorado. The mining district is located 80 miles southwest of Denver (Figure 1) on the east flank of the Mosquito Range. The area is typified by rugged relief with altitudes from 10,500 to 14,000 feet.]

Jan 1, 1962

By W. T. Walter

High-G centrifuges from five preparation plants were sampled to determine and quantify the various operating factors affecting performance. The operating factors that were considered include feed rate and percent solids, size of feed material, screen-basket type, hardness of coal and age of the flights. The performance parameters that were measured include product surface moisture, recovery and degradation of the coal. Regression equations with good significance levels were developed.

Jan 1, 1982

By Gordon M. Bell

Water has received little attention as a variable in flotation, even though it is a known fact that water hardness often has an adverse effect on purity and recovery, particularly on the flotation of non-metallic minerals. Because of this fact, process water used in some flotation plants is treated to reduce hardness to an acceptable level. In the laboratory, distilled water is usually used as the flotation medium in order to standardize conditions, whereas in flotation plants locally available water is used. At Rosiclare Works of Aluminum Company of America, Rosiclare, Illinois, where a vein-type of fluorspar deposit was being processed by flotation to make an acid-grade fluorspar concentrate until February of 1968 when the plant was closed, qualitative correlations had been observed between metallurgy and reagent consumption and the seasons of the year. The observed effects were thought to be due to seasonal variations in the quality of Ohio River water used as the flotation medium. Figure 1 shows the variations in total hardness and chloride contents of Ohio River water at Rosiclare for the period September 1964 through September 1967. During this period, the sulfate content varied from 85 to 245 ppm (as Na2SO4), the calcium from 90 to 160 ppm (as CaCO3) and the magnesium from 50 to 70 ppm (as CaCO3). The data in Figure 1 show that the total hardness and chloride contents are highest in the late summer and fall which are usually periods of low water and lowest in late winter and spring which are usually periods of high water.

Jan 1, 1970

By J. E. Spencer

Mesozoic and Tertiary mineral deposits in west-central Arizona are commonly associated with Mesozoic thrust faults and Tertiary detachment faults, respectively. Quartz-kyanite rocks and pyritic quartz-sericite schists with local anomalous gold are the product of probable Jurassic argillic alteration of Jurassic volcanic, sedimentary, and plutonic rocks followed by Cretaceous thrust burial and associated metamorphism. Slivers and sheets of Paleozoic carbonates along Mesozoic thrust faults were locally sites of syn-and post-thrust mineralization. Widespread brecciation along Tertiary detachment faults resulted in increased permeability along fault zones. Elevated thermal gradients also resulted from detachment faulting and apparently caused convective aqueous-fluid circulation along detachment faults and associated Fe+Cu±Au mineralization.

Jan 1, 1988

By T. O. Kuhl

The Royal-Mountain King Project is 7.2 kilometers (4.5 miles) northwest of Copperopolis, California. Reserves of 8,250,000 t (9,100,000 st) at 2.32 g/t (0.068 oz/st) gold will be processed at 2500 t/d (2750 st/d) from three pits. Production is scheduled to begin the first quarter of 1989. District geology consists of northwest trending sequences of Jurassic meta-sedimentary and meta-volcanic rocks. Three ore bodies are located along the Hodson fault which trends northwest and dips 40 degrees northeast. The Gold Knoll and North Pit ore bodies are hosted in carbonate and silica altered meta-volcanic rocks whereas the Skyrocket ore body is hosted in quartz stockwork zones in meta-sedimentary rocks. Gold is present as inclusions and micro-veinlets in pyrite.

Jan 1, 1989

By Ed Cope

The newly discovered South Arturo deposit is a Carlin-type, breccia-hosted, oxide gold deposit located on the Dee Mine property at the north end of the Carlin Trend in Nevada. The Dee Gold Mine was discovered in 1981 by Dee Delamar, a Cordex geologist. The property was put into production by Rayrock Mines in 1984. During its 16-year mine life, the Dee Mine produced about 18.6 t (600,000 oz) of gold from oxide ore at an average production rate of about 1.24 to 1.55 t/a (40,000 to 50,000 oz/year). In October 1997, Bar-rick Gold Exploration acquired the right to earn a 60-percent interest in the Dee property from Dee Gold Mines through an exploration farm-out agreement. Barrick Gold Exploration began exploration activities on the property in 1998 and vested in its 60 percent operating interest in 2004. However, the discovery hole at South Arturo was not drilled until July 2005 from atop the historic mine dumps located 300 m (985 ft) south of the Dee openpit. The discovery hole (BD-72) encountered a cumulative 75.6 m (248 ft) of oxide mineralization grading 1.9 g/t (0.055 oz/st) gold beneath 260 m (855 ft) of dump material and post mineral Tertiary Carlin Formation volcanic and sedimentary rocks. Oxidation within the deposit extends to depths greater than 610 m (2,000 ft). The deposit has passed the prefeasibility test and is presently in the feasibility stage. Exploration is on-going to enhance or enlarge the known deposit. The current resource for the deposit stands at 40.4 t (1.3 million oz) of gold. The South Arturo discovery is an example of an historic mining property yielding a new discovery through the diligent application of area selection criteria of the model type and persevering when early results were generally negative. Barrick?s original exploration pro-grams on the property were focused on the discovery of deep, high-grade sulfide deposits that would likely be mined by underground methods. As it turns out, South Arturo is mostly oxidized and will be amenable to mining by openpit methods

Jan 1, 2008

By J. Kircher

Nevada Goldfields' Aurora Mine consists of a 270 mtpd (300 tpd) precious metals mining and milling facility located 28 miles southwest of Hawthorne, Mineral County, Nevada and lies within five kilometers of the Nevada-California border. (Figure 1) Ore production presently is derived 85% from an open pit source with the balance from underground. The Aurora Mill is a compact conventional cyanide plant utilizing a carbon-in-leach extraction process followed by stripping of loaded carbon and electrowinning at Nevada Goldfields Kingston Mine, located near Austin, Nevada. Production commenced in December 1987 and annual gold production is currently 20,000 troy ounces of gold and 22,000 troy ounces of silver per annum, produced at an average cash cost of $178 per ounce of gold. Tailings handling at, Aurora was originally accomplished using a belt filter press producing a solid cake that was then transported to a final storage area. Although overall operating costs at the mine were' in the lower percentile of producing gold mines, the tailings handling portion of the operating costs were inordinately high.

Jan 1, 1989

By D. M. Hausen

Carbonaceous gold ores are ubiquitous to virtually all of the Carlin-type gold deposits along the Carlin gold belt in north central Nevada, representing the unoxidized "zones" of presumably extinct thermal spring systems of mostly Tertiary age. A period of subtropical weathering resulted in deep sub-lateritic zones in most deposits to several hundred feet below surface. Carbonaceous ores below this supergene profile of weathering have been investigated by various methods, including petrographic study, standard geochemical and organic carbon analyses, carbon and hydrogen isotopic ratios, electron-spin resonance spectra, infrared spectra, and DTA techniques. Results have been integrated with recent findings by other investigators utilizing fluid inclusion and thermal brine data to indicate a first phase hydrothermal solution temperatures and pressures at a minimum depth of 6 km under normal geothermal gradient. This phase resulted in the quartz-barite-calcite vein filling of the host rocks. Gold mineralization took place later at shallower depths. Primary organic material in carbonaceous ores from the Carlin and other mines appears to be a pyrobitumen residue derived from an old oil pool that had been heated by the thermal solutions, and from which the light hydrocarbon fractions were removed. Some of the bitumen was remobilized along silicified veinlets in the ore, but its role in the emplacement of the gold, itself, is not clear. The gold was localized submicroscopically in fine pyrite, mostly in framboids, and as fine metallic particles, but does not appear to be concentrated within the carbonaceous matter per se. However, reducing conditions associated with bituminous residues are believed to have been favorable for gold deposition.

Jan 1, 2013

By I. Mazalov, G. Ospanova

Introduction Today, uranium is of great interest because of its application to nuclear power and nuclear weapons. Kazakhstan has been an important source of uranium for more than fifty years. All uranium products are exported. Results In Kazakhstan uranium exploration started in 1948 and developed in several parts of the country thru mining of hard rock deposits. There are known around 50 uranium deposits in six provinces: Shu-Sarysuyskaya (57%), North Kazakhstan (18%), Syrdaryinskaya (15%), Ilyiskaya (7%), Caspian (2%), Balkhash (1%). In the Northern Kazakhstan province, KazSabton took over Tselinny Mining & Chemical Co in 1999. In this province the stockwork is of Paleozoic and Paleozoic folded complexes origin. In the Balkash province some mining of volcanogenic deposits occurred during the Soviet era. This province’s stockwork is of Endogenous origin.In the Ili province uraniumis mainly found in uranium-coal deposits formed by oxidation of the lignite beds roofs. In the Caspian province the Prikaspisky Combine operated since the 1960s a major mining and processing complex on the Mangyshalk Peninsula. This led to the founding of Aktau. It was privatised as Kaskor in 1992 and operations ceased in 1994. The uranium occurrence is associated with the phosphorous from fossil fish bone detritus conglomeration. In the Chu-Sarysu province, which has more than half the country's known resources, both Stepnoye and Tsentralnoye have been operating since 1978 and 1982 respectively. Uranium mineralization occurred in the regional stratum oxidation zones. In the Syrdarya province slightly to the west of the province’s center the No.6 Mining group has been operating since 1985. Uranium mineralization occurred in the regional stratum oxidation zones.

Jan 1, 2007

By H. W. Peirce

Arizona is a sun-belt growth-region where 13 tons of industrial (nonmetallic) minerals is being produced annually per capita. In 19B5, non-fuel mineral production reached $1.532 billion and consisted of metallic ($1.277 billion-84%) and nonmetallic ($253.5 million-16%) earth materials. Sand-and-gravel value was second only to copper. over 90% of the value of nonmetallics is represented by combined sand, gravel, cement, and lime. The remaining less than 10% ($25 million) was attributed mainly to stone, specific volcanic products (cinder, perlite, pumice), gypsum, clays, salt, zeolite, and others. Current interest in industrial-mineral development in Arizona is high, especially in the geologically complex Basin and Range region.

Jan 1, 1988

By D. C. White

The Vulture Mine near Wickenburg, Arizona was a major gold producer from 1863 to 1942, having yielded about 11,000 kg Au and 8,000 kg Ag. Gold occurs as coarse native metal and electrum in quartz veins and also finely disseminated within a quartz monzonite sill and its silicified wall rock. The sill is semi-conformable within a Proterozoic volcaniclastic-dominated sequence all dipping north about 35°. Early mining focused on the vein-hosted gold particularly in the immediate hanging wall and footwall of the sill. Later efforts included some open-pitting of the outcropping sill and adjacent altered and mineralized rock. Two sets of post-mineral faults have complicated the orebody geometry.

Jan 1, 1988

By O. D. Christensen

The Carlin Trend is a 60 km (38 mi) long northwest alignment of epithermal, sediment-hosted, disseminated gold deposits. Collectively, these orebodies contained more than 620 t (20 million troy ounces) of gold. The Carlin deposit, located near the center of the Trend, has become the "type" deposit of this class. There are, however, significant differences between the individual deposits. Six subdistricts can be distinguished, based upon geographic, structural, lithologic, alteration, mineralization style, and geochemical characteristics. They are, from northwest to southeast, the Bootstrap, Bluestar-Goldstrike, Lynn, Maggie Creek, Rain and Bullion (Railroad) subdistricts. Regional Geologic Setting The Carlin District is located centrally within the Great Basin Geologic Province. Host rocks for the deposits include sedimentary units that range in age from Ordovician to Mississippian, as well as a Jurassic-Cretaceous granodiorite stock. During the Early Paleozoic, the area that is now Nevada lay along the western margin of the North American continent. A westward-thickening wedge of sedimentary units was deposited offshore in a eugeoclinal basin; these vary from continental shelf carbonates toward the east to fine-grained siliceous clastic and cherty units to the west. Tectonic activity associated with the Antler Orogeny in Late Devonian to Early Mississippian time resulted in the eugeoclinal Western Assemblage rocks being thrust as much as 140 km (90 mi) eastward over time-equivalent transitional to miogeoclinal Eastern Assemblage rocks along the Roberts Mountains Thrust fault system. The leading edge of the Roberts Mountains Thrust plate formed the emergent Antler highland from which siliceous clastic sediment, eroded from the overriding eugeoclinal rocks, was shed eastward into the adjacent foreland basin. Erosional products derived from the overthrust plate are termed the Overlap Assemblage.

Jan 1, 1987

By J. D. Miller

X-ray computed tomography (CT) techniques have been developed for the medical services field in order to provide accurate internal images of the human body.(l-7) Now, a decade later, CT techniques are starting to be used in non-medical applications such as, non-destructive testing(8), flow pattern analysis(9), drill core examination (10,11), and coal characterization(12,13). In these fields of application, CT techniques offer the potential to extend our knowledge and understanding beyond that provided by more traditional methods of analysis. Although, CT systems involve very specialized and expensive equipment, the advantage of x-ray CT in revealing the detailed internal structure of an opaque material non-destructively should make it an important tool to provide a more complete analysis of mineral processing phenomena. X-ray CT systems generally consist of an x-ray source/collimation unit and a detector/data acquisition unit. The object to be examined is placed between the two functional units as shown in Figure 1. With this system the density array of selected cross sections of a chosen opaque object can be obtained in two dimensions. There are numerous areas in mineral processing to which x-ray CT technology can be applied and it is the aim of this article to identify these potential areas noting the advantages and limitations of the technology. Particular emphasis is placed on particle composition distribution and multiphase fluid flow measurements. In the case of particle composition distribution, liberation analysis and coal washability are considered. While in the case of multiphase fluid flow, swirl flow in the air-sparged hydrocyclone is given by way of example.

Jan 1, 1989

By Larry J. Hughes

Ground-based electrical geophysical techniques have be valuable for three indirect exploration strategies: "tracer" sulfide mineralization, 2) mapping structure with or controlling mineralization, and 3) mapping proven to 1) mapping? associated alteration zones. When sulfide mineralization is associated with gold, it often can be mapped using induced polarization (IP). This technique can detect pyrite in amounts as small as 0.2% by volume, and in some cases can distinguish pyrite from anomalies due to graphite and clays. A case history illustrates mapping sulfides in a shear zone. Structure and alteration mapping are often the domain of controlled source audio-frequency magnetotellurics (CSAMT) due to the superior lateral resolution and depth penetration of this technique. Typical CSAMT targets include silicified sediments and volcanics, faults, brecciated zones, argillic alteration, clay and graphite horizons, and certain lithologies. Examples of mapping silicification and mapping epithermal alteration are presented in CSAMT case histories over Cannon mine in Washington and Hishikari mine in southern Japan. In our experience, four things are needed to use geophysics effectively in precious metals exploration. First, the explorationist must correctly identify the exploration stage at which the geophysics is most useful. Second, the explorationist must clearly define the types of "tracer" mineralization, host geology, or alteration which need to be defined by the geophysics. Third, the right electrical technique needs to be applied to the problem to provide the best chance of success. Fourth, the explorationist must be willing to commit adequate finances to do the geophysics properly. With careful adherence to these principles, geophysics can greatly enhance exploration success while reducing the total cost of exploration.

Jan 1, 1989

By Richard F. Roethe

Surface coal mining productivity in the U.S. and Illinois has shown a general declining trend since 1969. The U.S. Department of Energy conducted an analysis in 1980 of the causes of declining productivity in different states. This paper presents a detailed analysis of changes in overall productivity and productivity in different functions such as overburden preparation, overburden stripping, reclamation, coal handling, etc. during the period 1970-1982. Statistical analysys techniques including multiple regression were utilized in the study.

Jan 1, 1983

By C. C. Hatch

As part of a general project to simulate a concentrator, the Brenda Mines Limited secondary crushing plant, located near Peachland, B. C., was sampled during the summer and winter of 1975 to develop a digital crushing plant simulator specific to the Brenda operation. The purpose of this simulator was to study the influence of manipulable process variables on important responses and to permit study of alternative circuit configurations if desired. This paper describes the simulation methodology employed and presents the results of a computer study of the secondary crushing plant (1).

Jan 1, 1979

By Charles B. Escapule

The first successful heap leach of silver ores in the State of Arizona has been under continuous operation since early 1976 at the State of Maine Mine, two miles southwest of Tombstone, Arizona. The silver produced from leaching old mine dumps at this property vas the first in the Tombstone mining district to achieve a 999+ purity. While cyanide leaching of silver and gold ores is a time-proven accepted practice, a relatively new method of treatment called "heap" leaching was employed. Heap leaching is a comparatively inexpensive fast way to recover precious metals from low grade material.

Jan 1, 1981

By S. Agarwal

The mining industry collects a significant amount of operational data. However, gleaning useful information from the terabytes of data is difficult, and not just because of the sheer volume of the data. Therefore, an automated tool was developed at the University of Alaska Fairbanks to go through data and apply very sophisticated statistical and neural network techniques, to identify the data streams that are important to a process. This paper presents results from the tool as applied to SAG mill data from a gold mine. The results were benched against commercial tool. Results indicate that there was little or no loss in performance by automating the very complicated process of neural network modeling. Therefore, the intent of the exercise, to examine if complicated modeling tasks can be automated, was realized.

Jan 1, 2011

By Cyrus W. Field

Metalliferous sediments constitute an important component of the sedimentary veneer that overlies basaltic oceanic crust of the Nazca Plate and elsewhere. Although first collected more than one century ago near the East Pacific Rise during the Challenger Expedition and recognized for their anomalously high content of Fe and Mn, occurring as very fine-grained, yellow-orange, oxides, hydroxides, and oxyhydroxides, it was not until the more detailed studies of Bostrom and Peterson (1966) that their geologic significance and concentrations of other transition metals were fully appreciated. The Nazca Plate is a dynamic lithospheric unit bordered by the Peru-Chile trench and the East Pacific Rise to the east and west, and by the Galapagos Rift and the Chile Rise to the north and south (Fig. 1). Samples employed in this study were taken from piston core recovered from the Nazca Plate (Fig. 2), D. S. D. P. drill core from the northeast Pacific (Dymond and others, 1973), ferromanganese nodules from dredge-haul s at several locations, and from hydrothermal mineral deposits of the Andes. Our efforts have been largely sponsored by the National Science Foundation through its International Decade of Ocean Exploration Pro- gram. The metalliferous fraction of these sediments is widespread, but generally small. Sedimentation is dominated by biogenic silica in the equatorial latitudes, terrigenous debris adjacent to the South American Continent, and by biogenic carbonate elsewhere, except at depths below 3500 m in the central and northwest parts of the Nazca Plate near the East Pacific Rise. Contributions of these distinctive sediment types are shown by the distributions of Si02, A1203, and CaC03 given in Figure 3.

Jan 1, 1982

By N. S. Tanious

This paper summarizes the results of an investigation into possibly the largest coal pillar failure in the USA. The newly opened drift mine is located in Southeastern Kentucky and worked an 11 feet thick coal seam, all other mines in the District worked seams 4-5 feet thick. The initial mine development consisted of 14 main entries (Fig. 1) which were driven in two sets of 7, under increasing depth of overburden. As the left seven entries came under deeper overburden the pillar ribs began sloughing which caused many of the concrete-block ventilation stoppings to crack. The mine management stopped the advance in the left seven and continued with the right seven entries. During the spring of the following year development resumed in the left seven, rib sloughage occurred again and this time severely cracked many stoppings and many were totally disintegrated from the excessive deformation. Within few weeks the sloughage was so heavy that many of these entries behind the active face were filled with piles of sloughed coal slabs. When the face reached a depth approximately 1150 feet, the sloughage became a slow, massive squeeze. The entry convergence (closure) reduced their height from 11 to 7-8 feet and the squeeze spread back to shallower depth covering an area roughly 300 pillars.

Jan 1, 1989