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By Stephen M. Voynick

Two hours driving time west of Denver, CO and 21 km (13 miles) north of Leadville, Bartlett Mountain rises 4,065 m (13,337 ft) high in central Colorado's Tenmile Range. Bartlett Mountain is one of Colorado's most recognizable peaks, especially when the late afternoon sun casts a surreal, reddish light across its most prominent feature - the Glory Hole. This is a gaping, half-mile-wide, 245-m- (800-ft-) deep crater. Created by subsidence from 60 years of massive underground mining, the Glory Hole is a monument to the Climax Mine, one of the great achievements in American mining and metallurgy. For most of this century, the name Climax has been synonymous with brilliant mining engineering, innovative metallurgical research and entrepreneurial promotion of a once-obscure metal - molybdenum. Climax overcame an array of economic, technological and social problems to become a model for underground development of massive deposits of low-grade ores. It is one of the few mines in the world where cumulative production is measured in the billions of dollars. The Climax mineralization was emplaced 30 million years ago. Magmatic intrusions formed a large, mineralized stockwork within the granite country rock of Bartlett Mountain. Associated hydrothermal events forced superheated metal- and quartz-rich solutions through fracture zones, silicifying the country rock and depositing huge amounts of molybdenite, or molybdenum disulfide. The mineralized rock, a light gray, finely crystalline, silicified granite, is laced throughout with blue-gray quartz veinlets containing molybdenite. Although the richest ores graded only about 1% molybdenite, the Bartlett Mountain deposit contained more than 2.7 Mt (3 million st) of elemental mo- lybdenum.

Jan 1, 1997

By Sumit Kumar Hota, Asadi Srinivasa Reddy, Ashok Kumar, Ashish Agrawal, Surajit Sinha, Chandra Sekhar, Tanay Ray

In the current operational facility, due to the absence of pellet pot facility, a novel technique is developed wherein the pellets with different chemistries prepared in the laboratory are fired in an induration machine by placing them inside the Inconel baskets. In the present work, an attempt is made to optimize the pellet chemistry by developing 2 different flux pellets, viz., low basicity (B2: CaO/ SiO2 = 0.3) pellets and high basicity (B2 = 0.9) pellets, and further the effects of basicity on pellet properties, viz., cold compressive strength, porosity, swelling index, reducibility index, and softening and melting temperature, are studied. It has been found through the multiple operational trials that increasing the basicity of pellets from 0.3 to 0.9 results into improving the pellet strength, reducibility and softening and melting characteristics. Moreover, it is observed that the swelling index of pellets is reduced by adding 2% MgO to both low and high basicity pellets that could be attributed to the formation of high melting point slag in pellets. The operational trial has resulted into producing pellets that exhibit a combination of desired mechanical strength, improved swelling, and reducibility index and possess better softening–melting behavior among all the chemistries studied.

May 24, 2022

By W. M. Cross

The hydrophobic character of sapphire surfaces in SDS solutions was examined with respect to the aggregative nature of the adsorbed surfactant phase. It was found that, at equilibrium, sapphire surfaces having adsorbed SDS bi-layers exhibited no contact angle. Conversely, when the adsorbed SDS was found to be mi-cellar in nature, sapphire surfaces developed significant hydrophobic character. The surface states as detected by Fr -IRIIRS conformational analysis were found to be reversible with temperature. The variation in adsorption density with temperature was studied by in situ Fr-IRIIRS. The isosteric heat of adsorption was calculated to be -1.6 kcal/mole. Although the adsorbed SDS was found to undergo a reversible phase change between 25 and 32°C, similar to SDS in solution, the extent of adsorption was not reversible with temperature.

Jan 1, 1993

By Ezz El Din Abdel Hakim Khalaf, Khalid S. Essa, Marc Munschy, Mohamed A. S. Youssef

This study focused on joint interpretation of the aeromagnetic and radiometric data to allocate and describe the structural elements and mineralization zones such as uranium, gold, and sulfide in the Gebel Umm Tineidba and its surroundings, Eastern Desert, Egypt. The study region is covered by exposures of Precambrian rocks such as gneisses, migmatites, ophiolitic mélange, metavolcanics, younger granites, and Quaternary sedimentary covers. The application of the total intensity magnetic and reduced-to-pole maps, power spectrum, analytic signal, tilt-angle, and local wavenumber maps helps in recognizing magnetic sources distribution, lineament features, and mineral zones delineation. The obtained results indicate that the depths of the deeper NE–SW, NNE–SSW, and N–S trending structures extend from 400 to 1750 m and shallower ones range from 100 to 400 m. Finally, the main trends of these structures affect the probable mineralization zones.

Sep 22, 2022

By E. Sabina Brady

Over the next two decades there will be significant trade and development opportunities in China for mining, engineering, equipment, and construction companies interested in becoming part of the development of China's chemical and fertilizer industries. At last count, China's phosphate ore reserves of 11.8 Gt (13 billion st), ranked fourth in the world behind the US, the USSR, and Sahara-Morocco. However, a recent statement by the head of the Ministry of Geology and Minerals, Sun Daguang, claims that with increased prospecting in the last few years, China's phosphate reserves now rank first in the world. Whatever the actual size of its known and potential reserves, China's present phosphate processing capabilities fall far short of demand, while the substantial progress that has been made in this area points out the severity of the problems that still remain. Since 1949 China has developed 181 mines and increased its phosphate concentrate production from 10 kt (11,000 st) to 10.86 Mt (11.97 million st). By the 1980s, China was the third largest chemical fertilizer producer in the world-although this claim is slightly misleading as China's nitrogen/phosphate potassium ratios are far from average world ratios and even further from US standards. According to the Sixth Five Year Plan promulgated in 1982, the country's development plans emphasize the expansion and upgrading of key energy and industrial sectors, including that of fertilizer production-specifically phosphate and potash. Within the framework of the plan, the Ministry of Chemical Industry's development priorities are to: • Increase potash production by 150% to 50 kt (55,115 st). • Raise phosphate fertilizer production 21.2% to 2.8 Mt (3.1 million st), 46 kt (50,705 st) of which will come from new projects constructed and completed within the Sixth Five Year Plan, with projected new production of phosphate concentrate and complex fertilizer in the next decades totaling 500 kt (551,146 st). • Commence work to increase phosphate ore production by 8.33 Mt (9.18 million st). Facilities for 2.43 Mt (2.68 million st) will be completed and come on stream by 1985. • Commence work to increase iron pyrite ore production by 3.69 Mt (4.07 million st), facilities for 2.9 Mt (3.2 million st) will be completed and come on stream by 1985. • Verify 600 Mt (661 million st) of new phosphate ore reserves. Since the promulgation of the Sixth Five Year Plan, Chinese authorities have announced that 70 key construction projects will receive top priority in the implementation of the plan. These projects include five in the chemical industry area, including the construction of four fertilizer plants in Urumqi (Xinjiang), Zhenhai (Zhejiang), Beijing, and Lucheng (Shanxi), and a pyrite mine in Yunfu (Guangdong). In addition, by 1985 the state will expand or construct three major phosphate mines: Wangji in Hubei, Kaiyang in Guizhou, and Kunyang in Yunnan. Fertilizer Ratios In 1982, China's fertilizer production was slightly higher than 12 Mt (13.2 million st) and consisted of 80% nitrogen, 19% phosphate, and 0.19% potassium. By 1985, state officials project that fertilizer production will reach 13.4 Mt (14.8 million st) and consist of 78.4% nitrogen (10.5 Mt or 11.6 million st), 21.2% phosphate (2.8 Mt or 3 million st), and 0.39% potassium (52.3 kt or 57,605 st). To attain the world average using the country's 1985 projected production level for nitrogen, China will have to double its 1985 phosphate production to 5.76 Mt (6.35 million st) and increase its 1985 potassium production almost 80 times to 4.1 Mt (4.5 million st). These numbers demonstrate the seriousness of the fertilizer production problem in China today and the long-term nature of the problem's solution. Development Examples Yunnan is the third largest phosphate-rich province in China with verified deposits of 1.9 Gt (2.1 billion st). Despite this abundance, the province only mines around 3 Mt (3.3 million st) of phosphate rock annually. In June of this year, Yunnan announced its intention to initiate 39 development projects within the next two and a half years, requiring an estimated $200 million worth of foreign investment. The three areas receiving the most emphasis will be:

Jan 9, 1983

By Yashar Pourrahimian, Magreth S. Dotto

Fragmentation by blasting is a critical process in hard rock mining. The blasting process and outcomes are highly influenced by rock mass properties and their response to higher stresses and loading rates. Each rock mass is unique, but some features affect the blast energy similarly, leading to similar outcomes. Having analyzed these features and their influence on blast results, they can be incorporated into the blast design to achieve better outcomes. This paper presents a numerical model validated by a case study from the actual mine blasts that studied the effect of rock mass properties on explosive energy production, attenuations, and overall blast outcomes. The results show that when the model parameters are calibrated based on real data, they can be used to simulate the fragmentation process and therefore be used to aid blast design.

Jun 25, 2023

By JOHN HOMER, Jacob L. Carr, Jonathan K. Hrica, Kathleen M. Stabryla, Iman Benbourenane, Jennica L. Bellanca

Given the recent focus on powered haulage incidents within the US mining sector, an appraisal of collision avoidance/warning systems (CXSs) through the lens of the available research literature is timely. This paper describes a rapid review that identifies, characterizes, and classifies the research literature to evaluate the maturity of CXS technology through the application of a Technology Readiness Assessment. Systematic search methods were applied to three electronic databases, and relevant articles were identified through the application of inclusion and exclusion criteria. Sixty-four articles from 2000 to 2020 met these criteria and were categorized into seven CXS technology categories. Review and assessment of the articles indicates that much of the literature-based evidence for CXS technology lies within lower levels of maturity (i.e., components and prototypes tested under laboratory conditions and in relevant environments). However, less evidence exists for CXS technology at higher levels of maturity (i.e., complete systems evaluated within operational environments) despite the existence of commercial products in the marketplace. This lack of evidence at higher maturity levels within the scientific literature highlights the need for systematic peer-reviewed research to evaluate the performance of CXS technologies and demonstrate the efficacy of prototypes or commercial products, which could be fostered by more collaboration between academia, research institutions, manufacturers, and mining companies. Additionally, results of the review reveal that most of the literature relevant to CXS technologies is focused on vehicle-to-vehicle interactions. However, this contrasts with haul truck fatal accident statistics that indicate that most haul truck fatal accidents are due to vehicle-to-environment interactions (e.g., traveling through a berm). Lastly, the relatively small amount of literature and segmented nature of the included studies suggests that there is a need for incremental progress or more stepwise research that would facilitate the improvement of CXS technologies over time. This progression over time could be achieved through continued long-term interest and support for CXS technology research.

Jun 17, 2022

By Dean S. Rogers

The conventional role of exploration, development and grade control is examined in this paper within the context of the many and varied types of gold occurrences which are found at the Dome Nine. The account endeavours to trace the development of the total ore evaluation process, from diamond drilling through the exploration and drifting stage, to the stope development and planning phase of the operation, with an emphasis on sampling techniques and assaying procedure. The concept of ore reserve calculations is developed and the practice of grade control is described. In summary, the role of the geological, the engineering and the mining department is presented in relation to the contribution each has to make in the evaluation and exploitation of ore from one of the world's classic Archean gold deposits.

Jan 1, 1984

By E. D. Gálvez, L. A. Cisternas, R. Acosta-Flores, F. A. Lucay

Froth flotation processes are carried out in flotation cells that are grouped into banks, and these banks are interconnected, forming a flotation circuit. A literature review shows the existence of papers related to flotation circuit design based on mathematical programming. However, due to the complexity of solving the mathematical model in most of the work, it is considered that a small number of species is present in the feed to the circuit, which differs from practice. In addition, simple bank models are generally used. This paper presents a methodology for designing mineral concentration circuits that overcomes the problems mentioned. It allows the use of more suitable cell or bank models and the inclusion of several species. The methodology is based on two phases. The first phase identifies the set of optimal structures using discrete values of stage recoveries, solving several mixed integer linear programming (MILP) problems. In the second phase, the optimal design for each of the structures obtained in the previous phase is determined using a suitable model for the recovery at each cell or bank, which results in a mixed integer nonlinear programming (MINLP) model. The design of a copper concentration plant with eight species and the design of a zinc concentration plant with three species and five size fractions by species are used to validate the proposed methodology. The structure of the cells in the rougher and cleaner banks deliver structures that are novel.

By Erik Westman, BEN WESTON, SETAREH GHAYCHI AFROUZ, KATHRYN DEHN

This study investigates the changes in seismic velocity of rockmass before and after three major seismic events to determine any potential identifiable precursory velocity changes associated with these events. Induced stress measurement is one of the challenging tasks in deep underground mining, with extreme impacts on the safety and stability of the mine. This study used p-wave passive seismic tomography to image the velocity redistribution within a rockmass, which can indicate induced stress level changes in the rockmass and detect the velocity changes that might precede a major seismic event or a rockburst. The ultimate goal of this research focus is to develop another tool for the deep-mining community that will help to increase safety and efficiency. For this purpose, the hypothesis of conventional mechanics, which implies induced stress at the hypocenter (as inferred by the p-wave velocity) increases until the seismic event occurs, is evaluated. It is found that the p-wave velocity did not increase at any of the three hypocenters prior to the seismic event occurring; however, the p-wave velocity did increase in the closest “zone center” for two of the three events. 

By R. Mensah-Biney

The adsorption of gold-thiourea complex onto a cation exchange resin, Amberlite 252, has been evaluated in a batch stirred reactor. The observed non equilibrium saturation capacity was 3.20 meg Au/g dry resin (620 kg/t) whereas the equilibrium ion exchange capacity was only 0.53 meq/g (103 kg/t). The enthalpy of adsorption was 4 -25 kJ/mole under equilibrium conditions and increased to 20-200 kJ/mole under non equilibrium conditions. Under non equilibrium conditions, the adsorption capacity of the resin decreased with increasing temperature and increasing thiourea concentration and increased with increasing gold concentration. This dependence of adsorption capacity on thiourea concentration and temperature may be a useful tool for elution of gold from the loaded resin. Scanning electron microscopy revealed evidence of deposition of elemental gold on the loaded resin under non equilibrium conditions. The proposed mechanism for "adsorption" of gold-thiourea complex onto this cation exchange resin consists of an ion exchange reaction followed by a reduction of the exchanged gold complex to elemental gold on the surface of the resin.

Jan 1, 1997

By T. H. Bagan

The Sixteen-to-One Mine was originally designed and operated using Blasthole Stoping with end slicing as the primary mining method. This method changed to Modified VCR Stoping in response to efforts to control dilution. The new method combines Blasthole Stoping with shrinkage methods, pillars, and reduced sublevel intervals to provide the most practical dilution control avail- able for low cost bulk mining.

Jan 1, 1987

By Francis J. Quinn

The Natural Gas Act, of 1938, which put interstate pipelines under the jurisdiction of the Federal Power Commission, did not place a protective competitive shield around such companies - nor does any provision of the act guarantee them a profit. Natural-gas pipelines are competitive with each other and also with the coal and oil industries. Gas distributing companies must compete not only with the coal and oil industries, but also with the electric industry. Natural gas has captured markets from oil, which had taken them from coal. Oil men contend that gas prices have: been, held to an artifically low level by regulation. The electric industry is moving into the space-heating market, which pleases the coal people because the coal industry's largest customer since losing the railroads to dieselization has been the electric companies. The coal industry is attempting to monopolize the industrial and electric generating market through government intervention, and this is being done under the guise of concern for the national welfare through advocation of a "National Fuels Policy purporting to, further the cause of fuel conservation. Such a policy is contrary to American principles and would result in the individual's loss of freedom of choice and ultimately, in less reserves of preferred fuels because of diminished exploration efforts.

Jan 1, 1961

By W. R. Reed, G. W. Luxbacher

Mine worker exposure to respirable coal dust and silica dust can result in coal workers’ pneumoconiosis and silicosis which are occupational respiratory diseases that have no cure and are ultimately fatal. In 2021 the Mine Safety and Health Administration reported just over 11,000 operating metal/nonmetal mines with the potential for silica dust exposure for just under 200,000 miners. The National Institute for Occupational Safety and Health (NIOSH) conducts respirable coal and silica dust research associated with mining through its Office of Mine Safety and Health Research. NIOSH respirable coal and silica dust research began under the U.S. Bureau of Mines (USBM), which initially examined silica dust, progressing to include coal dust, with a stronger focus after 1969 with the passage of the Federal Coal Mine Health and Safety Act. A review of extramural research to develop real-time respirable silica dust monitor is presented along with a brief history of silica dust regulation.

Feb 1, 2024

By Henning R. Norbom

Lime has been produced for many centuries. The simple pot kiln was one of the first devices used in this process. It was constructed of stone often on the side of a hill to reduce construction efforts and provide easy access to the top for feeding of limestone. It was fired from below with wood and coal. The pot kiln was very small and operated on the batch principle. The kiln being cooled between each batch, the fuel consumption was horrendous. The lime quality was poor with perhaps only one half of a batch being lime of suitable quality. Of the remaining half one part would be over burned and another part underburned. For centuries the lime burning technique was improved at a barely recognizable rate. One of the first major steps forward was the introduction of the continuous process vertical lime kiln. Although at first crudely constructed, the kiln had a refractory lining. It was charged with alternate layers of limestone and solid fuel usually in the form of coke. Continuous mode of operation, larger unit size and better heat distribution resulted in greatly improved fuel economy. However, quality of lime produced still left much to be desired. One problem was contamination by ashes from solid fuel.

Jan 1, 1978

By Hojong Kim, Isehaq Al-Nafai, Kwadwo Osseo-Asare

The standard Gibbs free energy of formation (ΔGo f, 298) of bastnasite, (Ce, La, Nd, Pr)FCO3, was estimated using four different methods. The obtained average values were − 1589.5 kJ/mol for CeFCO3, − 1599.5 kJ/mol for LaFCO3, − 1589.1 kJ/mol for NdFCO3, and − 1595.4 kJ/mol for PrFCO3. The value for cerium bastnasite, CeFCO3, was used to construct a potential vs. pH (Eh-pH) diagram to investigate the stability relations of cerium bastnasite. The diagram shows that CeFCO3 is stable in neutral to basic conditions (pH ~ 6.5–11).

By Charles L. Kimbell

Introduction Despite the focus on the so-called "high-tech" and service components of the economy, the minerals industry in 1987 continued to provide the world the overwhelmingly dominant share of the total raw material supply for all manufacturing operations. And, in the form of fertilizers and other soil treatment materials, minerals also supplied indispensable raw materials to ensure continued high production of the agricultural and forestry sectors of the world's economy. Moreover, the role of minerals as a source of construction raw materials was essential to that sector. On the basis of preliminary and partial statistics on world output of crude mineral commodities, 1987 appears to have been a year of further recovery from the recessional years of 1981-1983. The value of world crude mineral industry production (all mineral commodities including fuels) apparently advanced about 5% to nearly $1.1 trillion in terms of constant 1983 dollars.' That is significantly above the recently revised 1986 level of nearly $1.05 trillion, but still considerably below the record-to-date high of $1.27 trillion set in 1980, as shown in Table 1. That growth in value took place despite relatively flat world oil prices - oil being the most important component of the aggregate, as it has been for decades. There is insufficient information available to assess the total value of processed mineral commodities (refined metals, refined oil, manufactured fertilizers and the like). But a figure of $2.6 trillion (constant 1983 dollars) would be a quite conservative estimate for those materials derived only from primary or newly mined materials. And an additional, as-yet-unestimated increment should be added for processed materials derived from secondary raw materials - scrap and other reclaimed substances. From a world trade viewpoint, minerals and mineral products dominate in terms of tonnage. For example, in 1985, on a weight basis, mineral commodities including fuels constituted more than 58% of all goods moving through the Suez Canal and 53% of all goods passing through the Panama Canal. These waterways cannot accommodate giant tankers and ore carriers. So an even larger share of total oceanic trade is composed of minerals and mineral products. Yet, in terms of value, the share of the total accounted for by these industrial essentials is much lower than that accounted for by other commodities, most notably sophisticated high-tech equipment and other goods with a relatively high per-pound value. Worldwide data on the value of mineral export trade for 1987 is so incomplete at this writing that it is impossible to assess that actual level. Indeed, the compilation of similar available data for 1986 covers only the exports of nations with developed market economies. In 1985, these countries accounted for only 67% of total world exports of all goods. They accounted for only 41% of world exports of major mineral commodities: crude nonmetals; metal ores, concentrates, and scrap; mineral fuels; nonferrous metals excluding gold; and iron and steel. For these developed-market-economy countries, the value of exports of these major mineral commodities declined by more than 10% between 1985 and 1986. Most of the shortfall came as a result of a 26% drop in the value of fuels exports. If these patterns of

Jan 7, 1988

By J. M. Wempen, R. D. WEYHER, M. K. McCarter

Beam theory is a proxy for the behavior of intact, deforming roof strata above underground openings. Strong, stiff, intact strata have the ability to store significant strain energy when underground openings have large spans, as is typical of longwall operations. When strata fail, they may release some or all of this strain energy. Released energy is partitioned between fracture, thermal, and seismic energy. The tensile failure surface in simply supported beams is predicted to be free of shear stress. This prediction and the kinematic inability of crack slip during fracture make significant dissipation of energy by friction unlikely. In this study, the failure energy partitioning of Nugget Sandstone specimens is examined. Tensile fractures in specimens were induced using three-point loading tests. Elastic waves emanating from fracture events were recorded using an array of accelerometers. Accelerometers were placed within two crack lengths of the fracture surface, and the acceleration records are similar to strong motion seismic records. Spectral analysis was performed and used to develop synthetic, well-behaved, acceleration signals. Synthetic velocity signals were used to estimate radiated seismic energy generated by fracture. These estimates of radiated seismic energy demonstrate a potential means to constrain the minimum seismic partition. Fracture testing was performed on additional samples to estimate the fracture toughness of the sandstone. Synthesis of this data demonstrate a potential means to constrain a maximum seismic partition. Bounding the seismic partition for this type of fracture event could aid the detection and evaluation of seismicity emanating from longwall operations. Having better information about the location and magnitude of mining-induced seismicity within longwall overburdens could lead to better understanding of extraction sequencing and rock behavior in general. These energy estimates also support the hypothesis that dissipation of thermal energy by friction is small in bending tensile failure.

Jul 1, 2020

By J. O. Stephens

During the late 1940's and early 1950?s, the Westinghouse Combustion Turbine Division built and demonstrated a residual oil-burning locomotive on six eastern railroads. Plans were made to convert to burning pulverized coal, and a single combustor was operated at a full-pressure condition in the laboratory for about two years. During the mid-1960's to mid-1970's, there was considerable interest in coal-burning MHD and a combustor was developed which would also be applicable to combustion turbines. In the early 19801s, the BCR National Laboratory (BCRNL) became affiliated with the University of Pittsburgh, and a program was begun, supported by the Stare of Pennsylvania, to develop an all-purpose combustor for use with industrial and utility boilers and eventually with combustion turbines. In this paper, we review the work of almost 40 years, indicate our present position, and propose steps to be taken leading to efficient and environmentally acceptable power generation from coal, and specifically to coal-burning locomotives.

Jan 1, 1986

By M. T. Ityokumbul

Flotation columns and their variations are increasingly replacing conventional cells in mineral processing circuitry. While the operational characteristics of columns differ from those of conventional cells, the same scale-up methodologies are being employed in design. This practice may be attributed to poor understanding of the factors controlling throughput. The use of tall flotation columns is frequently justified on the requirement for increased particle residence time. It is shown that longer particle residence times in the column cell alone do not translate into increased recoveries. Throughput data from several industrial flotation column installations is presented. An attempt at using dimensional analysis to provide scale-up methodology for the factors controlling column throughput is made.

Jan 1, 1995