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By Jose M. S. Ramos

This paper describes the slope stabilization procedure at Cauê Mine, Companhia Vale do Rio Doce - CVRD, Itabira, State of Minas Gerais, Brazil. Cauê Mine, is a large open pit, to produce about 41 million tons of iron ore during 1974, and an intensive program of investiga Lion was carried out to provide the basic data for stabilizing its slopes, The ultimate rock slope in the W area will be about 400 m high with dipping angles decreasing gradually from top to bottom of the pit. The investigations started in 1969 and since then many geologists and engineers, from both CVRD and Geotécnica S/A., assisted by international consultants, have given their contribution to the achievement of solutions. It is hoped that this paper may contribute to the slope stability of other mines in tropical climate.

Jan 1, 1974

By P. Roghanchi

The difficulties associated with performing direct tensile strength test lead to development of indirect test methods, which are simple, less expensive, and less time consuming. Splitting tensile strength test (Brazilian test) is performed by applying two opposite concentrated compression load across the diameter of a disk specimen until the failure occurs along the loaded diameter. Theoretically, the load is applied over a small width as a line load, however, by increasing the load, the contact width between the loading jaw and the specimen increases as the specimen deforms. The main aim of this study is to investigate the stress distribution in (1) regular Brazilian specimen in traditional tests with loading jaws and (2) flattened Brazilian specimen with flat platens. A series of the splitting tensile strength tests and uniaxial compression strength tests are performed on three rock types: rhyolite, basalt, and limestone. Further, Numerical modeling studies are performed to investigate the effect of the contact between jaw and Brazilian specimen on stress distribution in the disc specimen based on the results from the experimentation. Finally, the stress distribution in the traditional Brazilian test specimen and the flattened end Brazilian test specimen were compared.

Feb 23, 2014

By Marline J. Veesaert

Urban quarries offer one of the greatest opportunities for profit in non-metallic mining with limited financial risk IF properly evaluated, planned and developed to meet market needs. Location, with respect to market, is the prime consideration. Geologic considerations and quality of rock are nearly as important. Cost factors and return on investment (ROI) are the principal financial considerations. Risk of capital is determined by weighing all factors that should be considered and how well judgements are based on information acquired. It is a simple, true axiom of business that an investment must be founded on amount of capital required with its expected return plus profit, expertise required to operate and time involved. Urban quarries generally offer excellent stone product market opportunities. Costs of land with mineral containment and processing operations are much greater than in rural areas. Environmental problems have become increasingly severe. Competition from other quarries in the market area is usually directly proportional to the profit attractiveness. Risk of capital (initial, developmental and operational) can be evaluated and reduced only by thorough analysis of the entire situation. Time and money expended on planning and preliminary investigations probably represent the most productive investment of available company resources.

Jan 1, 1977

By Michael A. Trevits

A mine fire represents one of the most dangerous and challenging safety issues facing underground mine operators. Given the right circumstances, a mine fire can occur at any location in the active or abandoned mine workings, can quickly grow beyond control, and threaten the welfare and livelihood of the entire underground workforce. The National Institute for Occupational Safety and Health (NIOSH), in partnership with the Mine Safety and Health Administration (MSHA), has been conducting an in-depth program of research addressing mine fire prevention, early and reliable fire detection, and mine fire suppression technologies. One portion of this program is focused on understanding the characteristics of mine fire combustion products and flame spread through large scale deep-seated (firmly established) fire tests and use of computational fluid dynamics (CFD) modeling. In this study, two deep-seated fire tests were conducted; one fire consisted of coal material and the other utilized the two most abundant fuel sources found in a coal mine: coal and wooden cribbing blocks. The fires were burned to completion while the combustion products were collected and analyzed. In addition, an array of thermocouples was placed within the body of the material to measure flame spread rate. The coal fire test information was then used to develop a CFD model of the fire. This paper describes the fire tests, provides insight into characteristics of flame spread, and presents the CFD modeling work results.

Jan 1, 2009

By Morton Handelman

The extraction of aluminum oxide_ from its ore is the initial step in the commerical production of metallic aluminum. This is most commonly done by the Bayer Process in which a caustic solution is used to dissolve hydrated alumina from the insoluable materials with which it is associate in bauxite. At the two-thousand ton per day Sherwin Alumina Plant of Reynolds Metals Company, the extraction residue from Caribbean ores is removed from the main pro¬cess stream as the underflow of a continuous clarifier-thickener operation. This sludge, prior to its ultimate r4jection from the process, is washed in a nine-step continuous countercurrent decantation system to recover physically-entrained mother liquor. Control of alumina production costs requires the optimum recovery of solubles from this residue which is generated at the same rate as the finished product. The equipment, operating techniques, controls and process variables which affect the efficiency of this soda recovery from Bayer Process red mud will be discussed.

Jan 1, 1959

By Doandy Yonathan Wibisono

Shotcrete is a versatile and widely utilized rock support material in mining and civil engineering projects due to its adaptability, strength, and efficient application. It immediately stabilizes rock surfaces, effectively controlling loose materials and preventing rockfalls in underground excavations. This paper focuses on assessing and analyzing data from observations of nozzlemen (shotcrete sprayers) during primary ground support activities in an underground mine. The study highlights the importance of nozzlemen’s skills in ensuring the quality of shotcrete application, which is critical for underground mining operations’ structural integrity and safety. A comprehensive training program and field support were implemented to enhance the nozzlemen’s proficiency. The training set covered theoretical knowledge and practical techniques to improve shotcrete application daily. Proficiency improvement was assessed using quantitative metrics, with rebound percentages decreasing by 5–14% as nozzleman competency increased. The results of this initiative showed significant improvements in shotcrete quality, including increased efficiency, reduced waste, and fewer reworks or rehabilitations. The findings aim to contribute to a broader understanding of best practices in shotcrete application and nozzlemen training, ultimately enhancing ground support application measures in the mining industry.

Feb 1, 2025

By Robert M. Dreyer

Although lateritic deposits have long been a principal source of bauxite and are becoming an increasingly important source of nickel, the problems in the evaluation of such deposits are not generally understood. In the evaluation of lateritic bauxite and nickel deposits, there are many similarities, but there also. are significant differences. It has long been recognized that laterites with commercial concentrations of trivalent metals represent the ultimate in the intense leaching of tropical soils. Any factors which effect-the rate of soil leaching will effect the form of local lateritic concentrations. Although the most intense leaching generally occurs on somewhat elevated areas of gentle relief where there is a free downward flow of rain water, the- effect of local rock structures in effecting varia¬tions in soil metal concentrations has-not been well understood - primarily because the laterite forms a masking blanket over the rocks from which the laterites were derived. All of the-factors which facilitate downward movement of water may effect greater surficial concentrations of trivalent metals. Such features as zones of fracturing, zones of greater rock permeability, and areas of karst topography may, therefore, be responsible for greater leaching. The variations in rock structures and the vagaries of ground water flow pat¬terns impart, to the laterites, rapid lateral and vertical variations in thickness and metal concentrations. Because of such rapid

Jan 1, 1970

By II Browne

After a decade of high copper prices, major mining companies are renewing their interest in purchasing operating properties and/or development of ore bodies. An existing operation carries with it a history that can present unique opportunities, while a greenfield operation allows for the establishment of a defined culture. Capital investments are distinctly different. A comparison of BHP Copper Robinson Operation, a greenfield property, and BHP Copper Tintaya Operation, a government owned Peruvian property, will provide insights into mining, concentrating and cultural differences between North and South American Operations.

Jan 1, 1997

By S. Middlemiss

The Indentation Fracture technique is being developed as a tool for use in comminution and mineral liberation analysis. Fracture toughness measurements for a number of mineralogical materials were made and comparisons were drawn between these and properties measured with the Ultrafast Load Cell drop weight apparatus. The technique has also been used as a probe to quantify differences in fracture properties at different areas in the microstructure of a material. In both a Utah limestone and a South African quartzite, material near a grain boundary fractures very differently to that in the bulk. Ongoing work is ultimately aimed at producing a comprehensive fracture model for a multi-mineral system based on its micro-fracture characteristics.

Jan 1, 1994

By Howard W. Earnest

The Rio Blanco Oil Shale Company completed a modified in situ oil shale retorting demonstration at its Tract C-a Lease in the Piceance Creek Basin of northwestern Colorado during the spring of 1982. This demonstration was the first MIS project with shafts rather than adits for access to the mining operation, and it involved several potential hazards which required that particular attention be paid to mine ventilation. Methane was first encountered during shaft sinking and ultimately resulted in the mine being classified gassy by MSHA. Secondly, we encountered hydrogen sulfide in association with the ground water, and this proved to be a more persistent problem than did the methane. Thirdly, in order to burn the underground retorts, it was necessary to provide for potential leakage of retort gases and to obtain a modification to the MSHA standard which forbids fires under- ground. This modification had a significant effect on the ultimate ventilation procedures at Tract C-a. An extensive under- ground air monitoring program was included in the ventilation system.

Jan 1, 1983

By Neel Gupta, Dustin M. Crandall, Brijes Mishra

X-ray computed tomography (CT) images of rock specimens often contain artifacts which must be corrected before scientific analyses are performed. This paper presents a new workflow of automated image processing to utilize poor-quality X-ray CT scan images. The workflow runs on the open-source image analysis software and efficiently separates desired features from low-contrast scanned images. The new workflow is a two-step technique using contrast enhancement and automated feature segmentation to generate noise-free binary images. The results of binary images using the proposed workflow and using a conventional thresholding technique are analyzed to show the quality of the proposed method. The paper also presents a workflow of estimating the structural geometries of features in two and three dimensions. The results of the structural feature analyses and computational time were compared between the open-source (ImageJ) and commercial image analysis software (Bruker Computed Tomography Analyzer). The commercial software was more computationally efficient, but the task-specific macros in open-source software enabled the user-desired automation in image processing and data extraction of desired structural features of comparable quality.

Sep 8, 2022

By D. K. Dysinger

The U.S. Bureau of Mines investigated leaching of chalcopyrite with sulfuric acid-oxygen under conditions anticipated during in situ leaching. A central composite experimental design was chosen to study oxygen pressures of 150, 300, and 450 psi, leach temperatures of 35?, 65°, and 95° C, oxygen-to-chalcopyrite mass ratios of 0.5, 1.0, and 1.5, leach times of 8, 16, and 24 hours, initial acid strengths of 0.6, 1.2, and 1.8 g H2SO4/g chalcopyrite and pyrite to chalcopyrite mass ratios of 0, 1, and 2. The leaching kinetics were consistent with the shrinking core model. A quadratic response surface model was used to determine linear and interaction effects of the design factors on rate constants from Arrhenius correlations.

Jan 1, 1993

By Donald L. Everhart

The National Uranium Resource Evaluation (NURE) program since 1974 has been designed to accomplish a comprehensive coverage of the 48 conterminous States and Alaska to evaluate the total uranium resources of the USA. This resource base includes both ore reserves and potential resources. Techniques include airborne radiometric and magnetic surveys, by hydrogeochemical surveys, surface and subsurface geologic studies, and the application of improved geochemical exploration and resource assessment methods (Table 1). In brief review, the current status of each of the five basic NURE elements is as follows: In the Aerial Surveys, in the conterminous 48 states, the flying has been completed in 89 of the NTMS 10 x 2° NURE quadrangles, and is in progress in 39 more (Figure 1). Complete quadrangle data have already been open filed for 46 additional quadrangles, for a total of 174 for which data gathering is either complete or in progress. In Alaska, the flying is complete in 42 quadrangles, and quadrangle data have been open filed for 34 more, for a total of 76 (Figure 2).

Jan 1, 1979

By J. E. Lowe

The unique application of a large walking dragline in the mountains of southern West Virginia was developed and implemented by Hobet Mining, Inc. Hobet is an independent operating subsidiary of Ashland Coal and is headquartered at the No. 21 Mine in Boone County, West Virginia, near Danville. Hobet also operates the 07 Mine located in Logan County, West Virginia, near Holden. Both mines are similar in equipment and manpower used; both produce over 2,000,000 tons of clean coal annually. Each site encompasses large, contiguous properties with access to rail service. The larger of the two is the Boone County property; it totals nearly 40,000 acres and has ample reserves. In 1977, Hobet was in the process of constructing a preparation plant (Beth Station) at its 21 Mine site with a capacity for two million tons. One of the first orders of business was to design a mine plan that would provide production for the capacity of the plant. Coal production would come from a more than adequate reserve base using the most economical mining methods available. Hobet looked at different deep and surface mining methods to use in order to develop the property; ultimately, it was determined that the mountaintop removal method with the use of a large dragline was the most economical way to develop reserve. Prior to this time surface mining in mountainous Southern West Virginia was generally done by contour mining and/or augering techniques.

Jan 1, 1993

By Nathaniel Herz, R. J. Adamson, C. M. Romanowitz, Frank W. Jr. McQuiston, C. D. Hoyt, Robert S. Shoemaker, P. H. O’Neil

1. INTRODUCTION In this section, precious metals are defined as gold, silver, and the platinum group metals comprised of platinum, palladium, iridium, osmium, and rhodium. If the first three years of the 1970's are the criteria, gold, silver, and platinum seem destined for a bright future. Gold advanced in price from the historic figure of $35 established in 1934 to over $100 per oz (1973). For the five years 1966 to 1970, silver consumption exceeded production by about 50%. The silver price appears to be definitely on the uptrend, and a price of over $3 per oz seems probable. On this basis (at 1964 costs) the United States has an estimated 5 billion oz of unmined silver. The fresh burst of interest in platinum with a surge of renewed price strength (end of 1972) is due to the activity in the automobile emission control area, where platinum re¬mains the front runner in the catalyst area. Some international financial experts believe that governments will not rush into reform of the monetary system, and "Special Drawing Rights" (SDR's) will gain increased standing as international mone¬tary reserve assets. Gold will continue to be reviewed as the ultimate store of value and will remain the global monetary base. Devaluation of the U.S. dollar caused by imbalance of import payments over ex¬ports is the basic reason that the price of gold will likely remain above the $90 per oz figure for the balance of the 1970's. Gold and silver usually occur intimately associated, and recovery methods are often closely related; however, they were assigned sepa¬rate chapters, because the major production of each metal is from ore deposits classified as either gold or silver. For example, the gold ore occurrences in South Africa, the world's leading gold producer, have a ratio of gold to silver of approximately 10 to 1. The ores at the Homestake Mine, Lead, S.D., the largest U.S. gold producer, are predominantly gold with a ratio to silver of approximately 5 to 1. Silver in each example is a byproduct. By this same classification, the largest U.S. silver producers are the silver ores of the Sunshine, Galena, and Lucky Friday mines in the Coeur d'Alene district, Idaho. However, the largest single-mine silver producer in the Free World is the Kidd Creek Mine at Timmins, Ont., where the occurrence is with sulfides of copper, lead, and zinc. Thus, the major gold production of the world is derived from those ores classified as gold ores; whereas, less than one-half of the silver production is from silver ores, and only a small percentage of the silver production is from gold ores. 2. GOLD Gold, the noblest of metals, has been mined for thousands of years. Its chemical symbol, Au, is derived from the Latin "aurum," meaning "shining dawn." A precious substance because it is one of the rarest metals, it has unique physical properties: it does not tarnish; it exceeds all other metals or alloys in malleability and ductility; it is a good conductor of electricity and is one of the most nonreactive metals. Its greatest strength is its indestructibility. It is the only metal mined at depths exceeding 10,000 ft. Since the early 1800s, its chief role has been as a medium of exchange, providing the basis for interna¬tional trade. In the past 15 years, however, gold has emerged as a useful industrial commodity. This role has been fortified by the estab¬lishment of a two-tier pricing system which maintains monetary gold prices at an established U.S. Government price, with industrial gold being priced higher by the free-market system. Occurrences and Production Native gold furnishes most of the world's production, since gold forms stable natural compounds with few other elements. Neverthe¬less, the metal is widespread with traces of it found in seawater and in the ashes of plants and animal material. Next to the native metal, the tellurides have been the most important gold-bearing minerals; these include calaverite, krennerite, slyvanite, hessite, and nagyagite. Native gold is invariably alloyed with more or less silver, but it is exceptional to find any other metal in the alloy. It is found in veins associated with quartz, calcite, alunite, other gangue minerals, and with various sulfides. Sulfide minerals in order of frequent associa¬tion are: pyrite, galena, chalcopyrite, sphalerite, arsenopyrite, tetrahe¬drite, and pyrrhotite. Small amounts of metallic gold are commonly disseminated through such sulfides. When considerable amounts of silver occur in gold, the mineral electrum is formed. In a few deposits, gold and mercury form natural amalgam. Native mercury is formed by weathering from cinnabar and other mercury minerals. Among the minerals sometimes mistaken for gold, pyrite, marcasite, and especially chalcopyrite may be men¬tioned. The flakes of biotite and other micas, especially when partially oxidized, also may imitate it closely. World gold reserves never have been estimated carefully. Esti¬mates indicate that present world reserves approximate I billion oz, of which about 60% occurs in South Africa and 20% in the USSR. World gold output is dominated by South Africa which produces two-thirds of the world's production from reserves that are adequate to maintain existing output levels. South African gold output comes from approximately 50 large underground operations that mine and mill 70 to 80 million tons of ore annually to recover 30 to 32 million oz of gold. The USSR is the second largest gold producer, followed by Canada and the United States (see Table 1). Gold production in the United States and Canada rose to high levels in the 1930's, following the increase in price from $20.67 to $35 per oz and with an abundance of good labor due to depression in other industries. Production of over 10 million oz in 1940 was behind only that of South Africa. World War II caused a precipitous drop in gold output due to the imposition of War Production Board Limitation Order L-208 issued in October 1942, which caused over 9,000 gold mines in the United States to shut down, most of which never reopened. The U.S. Treasury, which suspended purchases of newly mined gold in 1968, had been the sole buyer of U.S. produced gold since 1934. This created the two-tier pricing system, and in March 1972 the President signed into law a bill authorizing a $3 increase in the official price of gold to $38 per oz. In February 1973 the President ordered a second devaluation of the dollar, amounting to about 10% which raised the official price to $42.22 per oz. The erratic development of the gold market, which has seen the

Jan 1, 1985

By R. M. G. S. Berezowsky

An atmospheric ammoniacal thiosulphate leach system was developed to recover gold and silver from residues of the ammoniacal oxidation leaching of sulphidic copper concentrates. Extractions of 88 - 95% Au and 83 - 98% Ag were attained within 2 to 4 hours at 40 - 60°C in thiosulphate leaching of the oxidation leach residues of Manitoba chalcopyrite concentrates analyzing 24.6% Cu, 0.18 oz/ton Au and 4.26 oz/ton Ag and a complex British Columbia chalcopyrite/tetrahedrite concentrate analyzing 18.5% Cu, 0.27 oz/ton Au and 276 oz/ton Ag. Parameters affecting the Au and Ag solubilization included thiosulphate, ammonia, and cupric ion concentrations, temperature, retention time and the degree of Cu extraction and sulphide oxidation in the primary oxidation leach. The precious metals were recovered from the thiosulphate liquors by zinc dust cementation.

Jan 1, 1979

By Charles A. Beasley

Increased technical and legislative analysis by all parties of interest could result in more efficientand better directed regulatory legislation in the mining industry. Efforts to forestall or frustrate legislation through massive lobbying and public relations efforts are seldom effective over time and often lead to more stringent and far reaching legislation than necessary. The Federal Coal Mine Health and Safety Act of 1969 is perhaps an outstanding example of such insufficiences; a future example may well be regulatory surface mine legislation. Although a lack of extensive hard data seldom enables rapid or sophisticated analysis early in the legislative process, even preliminary analysis may be sufficient. Simple statistical analyses of available data, assessment of the legislative rationale, and subjective appraisal of other non-quantifiable constraints to improved mine safety. An average of 115 underground fatalities at an exposure frequency rate of 0.67 can be reasonably expected in the immediate future, under existing levels of technology, degree of regulation, and economic conditions. If gross unrefined estimates of 6 preparation plant, 5 surface, and 30 strip mining fatalities are assumed, the total fatality industry level could be expected to approximate 156 Serious professional, economic, and technical constraints within the the industry probably preclude any major decrease of these accident levels within the near future

Jan 1, 1972

By M. Misra, I. A. H. Schneider

The flocculation of -38 pm calcite, hematite and kaolinite aqueous suspensions by the yeast Candida parapsilosis and products derived from rupture of the microorganism was studied. Flocculation of hematite suspensions by the microorganism and its derivatives readily takes place between pH 2.8 and 11.4. Maximum flocculation occurs at about pH 6.5. Flocculation of calcite suspensions by the microorganism and its derivatives readily takes place between pH 7.0 and 11.8. Maximum flocculation occurs at about pH 10.0. Flocculation of kaolinite suspensions was less than that for the other two minerals. However, a soluble fraction derived from the rupture of the organism functioned as a good flocculant for the mineral, albeit at an increased concentration, between pH 2.6 and 11.5. Maximum flocculation occurs between pH 6.8 and 7.2. An attempt is made to relate the behavior of the various systems to the surface characteristics of the minerals and the surface and chemical properties of microorganism and its derivatives. Experimentation used to evaluate the flocculation includes actual flocculation tests, microelectrophoresis measurements and scanning electron microscopy.

Jan 1, 1994

By J. A. Barsin

Stationary air pollutant sources established prior to the New Source Performance Standard (NSPS) are not, at present, subject to federal emissions regulations. However, proposed legislation could require many existing stationary sources to reduce emissions. This paper will report upon the laboratory work undertaken to date by B&W to commercialize a limestone system for sulfur capture both in pulverized coal and cyclone coal-fired utility boilers. Updates will be provided on the US EPA/State of Ohio/Ohio Edison/B&W sponsored pulverized coal full-scale limestone injection demonstration, and on the EPRI/Baltimore Gas 8 Electric, Atlantic Electric/B&W sponsored laboratory-scale cyclone coal limestone injection investigations.

Jan 1, 1986

By Kewal K. Kohli, Richard E. Thill, Syd S. Peng

The results of unpublished investigations into surface subsidence from coal mining in the Northern Appalachian Coalfield are summarized. These investigations were carried out by various coal companies and the State of Pennsylvania in the sixties and seventies. Subsidence data were collected and analyzed from 10 room-and-pillar panels in 5 mines in the Pittsburgh coal seam. Results show that angle of draw ranges from 26° to 33° and subsidence factor from 0.42 to 0.72; surface heating generally occurs beyond the edges of the panel, the amount and extent of which vary; waviness occurs in the subsidence profile if a substantial number of pillar stumps are left in irregular patterns; interpanel effect is significant; time-dependent subsidence exists, but varies for different panels; and surface slope does not seem to affect the amount of subsidence.

Jan 1, 1982