Search Documents

By S. Todd Mickleborough

The geostatistical technique of conditional simulation is applied to measure the uncertainty in factor of safety predictions for soil slopes where there is incomplete knowledge of the spatial distribution of soil properties. A case study considers a natural clay slope in Canada. The sequential indicator simulation technique is used as a means for generating a series of spatial maps of soil properties for this site. These maps approximate random draws from the conditional probability density function that characterizes existing uncertainty in the spatial distribution. Factor of safety determinations are then made for each simulated map using the simplified-Janbu approach, where the computations are performed with a new computer program that can operate on irregular spatial profiles of soil properties specified on a discrete grid. A unique capability of this approach is the ability to generate the distribution of factor of safety conditional to the type, position, and value of existing site characterization measurements. This capability should reduce uncertainty in FS predictions.

Jan 1, 1993

Refractory copper ores (CROs) in central Africa contain copper minerals that are locked up in a micacious solid matrix or associated with carbonate, sulfide and phosphate minerals. Several researchers have reported that the recovery of copper from CRO material by an acid-leaching process is not economically feasible, due to the presence of excess gangue-acid-consuming minerals such as calcites, dolomite, asbolane and iron oxides. Since the proportion of acid-insoluble copper (CuS) is about 28% of total copper and total free sulfur is extremely small, sulfide flotation was considered unfavorable. Consequently, hundreds of millions of tons of CRO material have been stockpiled specifically at the Nchanga Mine of Zambia. In terms of copper distribution in CRO material, a significant portion of total copper exists as carbonates (39%) and oxides (17%), while 28% of the copper is acidinsoluble (CuS). The rest of the copper is in the form of carbonates (16%) and (hydr) oxides (17%). This means that only about 72% of total copper is recoverable through the non-oxidative acid-leaching process. In this study, batch leach tests were performed on CRO solids (d95 = 95%) to establish the gangue acid consumption values at different feed pH values and to evaluate the leaching characteristics of copper, manganese and iron within the CRO material. Subsequently, continuous leach tests were performed on CRO solids (106 um, 80% passing) using optimum leach conditions derived from batch tests. This paper aims to show that sustainable copper recovery can be achieved by selecting leaching conditions whereby gangue acid consumption (GAC) values become significantly small and the final concentration of manganese and iron in the leach solution are appreciably low.

Nov 1, 2011

Refractory copper ores (CROs) in central Africa contain copper minerals that are locked up in a micacious solid matrix or associated with carbonate, sulfide and phosphate minerals. Several researchers have reported that the recovery of copper from CRO material by an acid-leaching process is not economically feasible, due to the presence of excess gangue-acid-consuming minerals such as calcites, dolomite, asbolane and iron oxides. Since the proportion of acid-insoluble copper (CuS) is about 28% of total copper and total free sulfur is extremely small, sulfide flotation was considered unfavorable. Consequently, hundreds of millions of tons of CRO material have been stockpiled specifically at the Nchanga Mine of Zambia. In terms of copper distribution in CRO material, a significant portion of total copper exists as carbonates (39%) and oxides (17%), while 28% of the copper is acid-insoluble (CuS). The rest of the copper is in the form of carbonates (16%) and (hydr) oxides (17%). This means that only about 72% of total copper is recoverable through the non-oxidative acid-leaching process. In this study, batch leach tests were performed on CRO solids (d95 = 95%) to establish the gangue acid consumption values at different feed pH values and to evaluate the leaching characteristics of copper, manganese and iron within the CRO material. Subsequently, continuous leach tests were performed on CRO solids (106 um, 80% passing) using optimum leach conditions derived from batch tests. This paper aims to show that sustainable copper recovery can be achieved by selecting leaching conditions whereby gangue acid consumption (GAC) values become significantly small and the final concentration of manganese and iron in the leach solution are appreciably low.

Jan 1, 2011

By Vivek Priyadarshi, VIVEK KUMAR HIMANSHU, A. K. Vishwakarma, M. P. Roy, A. K. Mishra, RAVI SHANKAR

The nature and orientation of joints in rock strata affect the damage pattern under explosive loading. Most of the limestone deposits in India are found with severity of joints. Categorically, these joints may have variable orientations such as dipping out of the blast face, inside the face, horizontally or having strike parallel to the face. The damage pattern under the varying category of orientation will be different. Accordingly, a numerical model in Ansys-Explicit Dynamics was prepared to compare the damages of rock mass under different joint orientations. The physical nature of a joint reflects frictional and stiffness behaviour. Accordingly, the damages have been compared under bonded and frictional nature of joints. The output damage pattern from the model has been validated on the basis of blastability index proposed by Lilly. Different limestone mines in India show different nature of jointing in their rock strata. Accordingly, the blasting outputs from three different limestone mines, viz. Rawan limestone mine, Sagmania and Birhauli limestone mine and Injepalli limestone mine, have been compared along with their blast design parameters and the nature of joint. The comparative results show that the closely spaced horizontal joints support maximum in burden movement and rock fragmentation due to blast.

Nov 23, 2023

By E. A. Lauha

The Goldstrike Mine is in Eureka County, Nevada, U.S.A., approximately 23 miles northwest of the town of Carlin. The mine is at the north end of the Tuscarora Spur of the Tuscarora Mountains at elevations of 5,300 feet to 5,950 feet. It is part of the Bluestar/Goldstrike sub-district of the Carlin Trend, a northwest alignment of sediment hosted, disseminated gold deposits. The Carlin Trend includes over 15 major gold deposits with production, reserves and geological resources of approximately 65 million ounces of gold (Figure 1). In the Bluestar/Goldstrike sub-district, there are seven major deposits: Betze, Lower Post, Post, Genesis, Bluestar, Purple Vein and Deep Star, plus numerous smaller deposits (Figure 2). Production, reserves and resources for the sub-district are approximately 40 million ounces. Betze and Purple Vein are located on property controlled by Barrick Goldstrike Mines and Bluestar and Genesis on Newmont Gold property. Post, Lower Post and Deep Star occur both on Barrick and Newmont property.

Jan 1, 1993

By Emre Karakaya, Niyazi Bilim

Boreholes are used for many purposes in mining operations, petroleum engineering, and construction works. Numerous factors affect the performance of drilling equipment. Researchers continue to work on the variable drilling parameters that can be adjusted in order to reach more efficient drilling operations. Penetration rate is an essential indicator in drillability analysis and estimating. This parameter is of great importance in mining projects. There are almost no models that can estimate the penetration rate for core drilling operations. Under the abovementioned circumstances, this paper focuses on developing models that allow estimating the penetration rate based on rock material properties. During the conduct of this study, drilling experiments under 11 different pressure forces were performed on 8 different rock units, and the equations which estimated the penetration rate depending on the physico-mechanical properties of the rock samples were derived. Experiments were carried out under different pressure forces to investigate the effect of the pressure force on the derived estimation models. The obtained results allowed deriving equations that ensured estimating the penetration rate based on the physico-mechanical properties of the rocks and the applied pressure force. Using these equations, the penetration rate in core drilling operations can be estimated.

Sep 30, 2020

By E. Neumann

With fuel costs unstable but escalating, solid fuels are playing an increasingly larger part in industrial concerns. Coal, petroleum coke and wood are examined from a burner system design viewpoint and from operational experience in kilns, hot gas generators, etc. The burner of today must also handle multi-fuel tasks and allow immediate, painless switching from one fuel to the next as well as the simultaneous burning of two or mope fuels. The paper discusses the principle of burning alternate pulverized fuels as well as the practice both in the United States and around the world.

Jan 1, 1983

By Chee S. Theng

As the 2017 president of the Society for Mining, Metallurgy & Exploration Inc., I am pleased to present the 2017 issue of the Transactions of the Society for Mining, Metallurgy & Exploration Inc., Vol. 342. A significant portion of the contribution that we make as a professional society is the publication of professional and technical papers that accelerate the advancement of scientific knowledge and enable the transfer of technology. Communication within the mining community is the key to a successful society. This technology exchange continues a tradition that dates back to the 1871 meeting of 22 mining engineers in Wilkes-Barre, PA, that resulted in the founding of the American Institute of Mining, Metallurgical and Petroleum Engineers (AIME). Those individuals envisioned that these transaction volumes “would form a most valuable and greatly needed addition to our professional literature.” This volume fulfills that pledge. The 2017 Transactions contains some of the most interesting research and insights from the past year and features an international slate of authors spanning industry, academia and government. Papers include the latest findings from the U.S. National Institute for Occupational Safety and Health (NIOSH), a special review article on Heap Leach Modeling, and articles from two Special Issues on Rare Earths. The 2017 Transactions consists of a total of 54 technical papers, encompassing all 21 papers published in 2017 in the Technical Papers Section of Mining Engineering (Vol. 69) and all 24 papers published in 2017 in Minerals & Metallurgical Processing (Vol. 34). Additionally, this volume contains 9 papers that are being published for the first time in this issue. The papers presented in this volume were written by some of the most distinguished professionals in the industry worldwide. All of the technical papers were peer-reviewed. The process of review and publication requires much hard work by authors, reviewers and our Publications staff. As the 2017 president of SME and on behalf of all our members, I would like to extend our gratitude to all whose volunteer efforts contributed to the publication of this volume.

Jan 1, 2017

By A. Singh

"Considering the dominant role of fertilizers in global phosphate production, it is evident that with the ever increasing development in agriculture there will be a growing demand for phosphate beneficiation. With the rapid depletion of high quality reserves, investigations into more complex and lower grade ore bodies are required. The Minerals Processing Division at Mintek has been involved in process development and flowsheet design projects on phosphate resources since 2003. This paper will discuss the processes that Mintek has explored and employed to upgrade various phosphate ore bodies (>30% Phosphorous Pentoxide (P2O5)) in preparation for end user application. These are aimed at an improved understanding of ores in terms of their varying mineralogy and the development of appropriate process routes to meet product specification. OVERVIEW OF MINTEK Mintek is a state owned science council that undertakes R&D, consulting and sells products and services into the minerals beneficiation industry. Mintek has been in existence for 83 years with a current permanent staff complement of 750 of which 300 are professionals with a tertiary education. Being a non-profit organisation, the majority of funding comes from state grant and earmarked funding. All research is needs-driven exploring innovation through technology and process optimisation trends. Owing to a solid base of expertise, extensive laboratory and pilot facilities, and a historical database of knowledge, Mintek is well positioned and equipped to execute projects on a scoping, feasibility, prefeasibility and bankable level. USES OF PHOSPHATE Phosphate is the component in fertilizer essential for root and stem development in plants as well as rejuvenation of harshly depleted soil for which there is no agricultural substitute. Phosphate rock is essential for global food security with 87% used in the production of fertilizers. In agriculture as fertilizer, phosphate is one of the three primary plant nutrients in addition to nitrogen and potassium. In former times, it was simply crushed and used as is, but the crude form is now only used in organic farming. Normally it is chemically treated to make Single superphosphate (SSP), Triple superphosphate (TSP), or Mono-ammonium phosphates (MAP) and Di-ammonium phosphates (DAP), which has a higher concentration of phosphate and is more soluble, thus more suitable for plant absorption."

Jan 1, 2018

By Frank E. Sullivan

The separation of liquids from granular materials has been widely studied by a number of: investigators over a period of years in an effort to more fully understand the physical phenomenon which occurs. Liquid may be removed from solids, or partially removed, by gravity separation, mechanical separation' or heat drying. Mechanical separation is advantageous when compared to heat drying principally from a cost saving standpoint and also on certain materials which are heat sensitive. It is realized however that mechanical separation of liquids has certain practical limitations. In order to evaluate the efficiency of mechanical separation and predict the extent of, liquid removal, it is first necessary to study the forces which hold the liquid to the solids. From a very practical observation using gravity drainage, it is soon obvious that a pile of coarse solids will drain faster and retain less liquid than a pile of finely divided solids of the same material. For commercial operations it is important to estimate the residual liquid which will remain after a mechanical separation. Batel (1) explored the various quantities of liquid present in the interstices of the bulk granular material. From his work and other authors which he has correlated in one of his recent papers, various formulas are now available which permit an empirical relationship to be developed showing residual moisture versus mechanical separating forces.

Jan 1, 1965

By R. L. Morse

The thermodynamic program is similar to previous mine ventilation programs but has been expanded to consider the compressibility of air. The thermodynamic program does consider: 1) air density variations, 2) humidity changes, 3) intake, exhaust, and underground fans, 4) heat transfer between rock and air, 5) refrigeration of heating plants, both surface and underground, and 6) heat generated by equipment, both diesel and electric. 110st of the compressibility factors are handled in the branch calculations. The field survey necessary to supply-data for this program is quite similar to the basic base and leap-frog pair of stations method used with most incompressible mine ventilation programs. The thermodynamic program is a complete package of ventilation network analysis which can provide mine management with good operational control and planning of mine ventilation systems.

Jan 1, 1977

By W. K. Katoto

The Tailings Leach Plant (TLP) of the Zambia Consolidated Copper Mines Ltd at Nchanga was commissioned in 1974 as the world's first largest successfully operated agitation leach SX-EW plant for copper production. The design, development and operation of the plant soon after commissioning termed as TLP stage II has been described by Holmes et al (1). In the initial phase the plant was designed to treat approximately 25,000 tonnes per day of current flotation tailings from the Nchanga Concentrator operations, and had a design capacity to produce 75,000 tonnes per annum of copper. Further expansion took place in 1986, and TLP stage III was successfully commissioned to treat an additional 20,000 -25,000 tonnes per day of large reserves (over 135m tonnes) of reclaimed tailings stockpiled since the early 1930's in four paddock type tailings dams (T01 to T04). The salient feature of TLP stage III expansion described by S K Mwenechanya et al (2 -3) was the installation of the world's largest Horizontal Belt Filter Plant with 26 filters each of 80 m2 filtration area.

Jan 1, 1996

By V. A. Mironenko

The combined study of ground water regime and rock deformations has resulted in the theoretical substantiation of the common principles for analysis of the hydrodynamic and geomechanical processes Within the scope of unique scientific direction -hydrogeomechanics (Mironenko and Shestakov, 1974). The hydrogeomechanical models are widely used now for the analysis and forecasting the extremely important processes connected with the safe and efficient mining operations, as well as with the protection of geological medium. Among these processes are: -deformations of the open-pit slopes and spoil dumps; -consolidation of rocks due to the ground-water pressure drop; -water-end-rock material inrush into mine workings caused by deformations of the undermined rock mass; -geodynamical processes due to the changes in ground water regime; -artificial hydrofracturing in rocks; -transformations of clay linings under the tailing ponds and other technical water basins.

Jan 1, 1990

By Thomas F. Connors

The end of an era is here. The pony-express era of industrial relations in the coal industry is ending. Those professionals who know it must end to insure the industry's future are happy, relieved, but somewhat saddened. They are sad because it did have its elements of suspense, thrills, frustrations, and at times, plain fun. The days of the Company town are ended; the wildcats are declining; violence (while a big part of today's industrial relations) is beginning-to decline. The spirit of sound industrial relations is beginning to take hold. This has to happen for the industry to compete in today's economy and it is causing major changes for those who have grown accustomed to the pony-express type industrial relations.

Jan 1, 1981

By Evan J. Owen, Virginia T. McLemore

The Zuni Mountains, located in Cibola County, New Mexico is an uplifted area that exposes Proterozoic igneous and metamorphic rocks overlain by Permian and younger sediments. Sedimentary-hosted Cu deposits and fluorite veins in the district have recorded production, but other deposits exist. Proterozoic ultramafic rocks may host Ni and PGE. A recent regional stream sediment survey collected 76 samples as part of an exploration geochemistry course at New Mexico Tech with the goal of assessing the critical minerals potential of the district. Whole rock and trace element chemistry of the sediment samples (<2 mm) show a variety of critical minerals possibly worthy of future targeted exploration including up to 700 ppm As, 2100 ppm Ba, 26 ppm Bi, 25 ppm Co, 640 ppm Cu, 145 ppm Ni, 110 ppm Sb, 170 ppm V, and 500 ppm Zr. Positive correlation between Bi, As, Cu, and Sb suggest that these critical minerals are found together within copper veins related to shear zones in the district. Samples collected from streams that drained outcrop of mafic and ultramafic rocks were found to generally contain more Ni, Co, and V. Samples elevated in Ni will be reanalyzed for PGE.

Feb 1, 2025

By Harrison R. Cooper

Approximately 40 concentrators throughout the world have successfully adopted computer control for flotation circuit operation since 1969. Successful use of flotation control, gaining up to 2% efficiencies, has largely derived from effective employment of on-stream slurry analyzers and integration of key measurement data through digital processors. Requirements for reliable measurement have also led to improved functional reliability in magnetic flow meters, pH, reagent feed, and other key elements. Methods used in computer control of flotation will be reviewed and variations in operating philosophies will be described with reference to the approaches taken to flotation automation.

Jan 1, 1979

By Kot F. Unrug

When reading different studies discussing trends in coal mining, it appears that a substantial expansion of output by the year 2000 is predicted, even in the most pessimistic forecasts. Depletion of shallow, easy-to-mine deposits is only a matter of time, and the future average mining depth will increase. The proportion of slope to shaft mines operated during the next decades will change in favor of the shaft mines. Since an increasing amount of shafts in new nine developments seems to be inevitable, it appears appropriate to focus more attention on shaft design criteria. Some valuable papers have recently been published (1) that emphasize geotechnical aspects of shaft design. In the discussion that follows some other aspects of design criteria will be evaluated.

Jan 1, 1984

By M. Polat

A combined heavy medium-flotation process which incorporates the advantages of two widely employed cleaning methods, namely, heavy medium separation and flotation was used to achieve improved separation of coal from ash at fine sizes and to recover the heavy medium as a substantially recyclable product. The investigation was carried out in two successive phases. In the first phase, tests were performed to deter-mine the effect of different variables such as the medium density, flotation time, magnetite type, etc. on the efficiency of the process using in-plant samples from Homer City Coal Preparation Plant. In the second phase, the optimum conditions determined in the first phase were employed to determine the applicability of the process to a few Central Pennsylvania coals. It was observed that the process was very effective in recovering the magnetite. In most of the cases investigated, the magnetite was separated from the non-magnetic material at approximate-1 to 99 % recovery with a grade ranging from 95 to 99 %. The grade of magnetite decreased with increase in ash content of coal and with decrease in size of magnetite.

Jan 1, 1992

By M. Sunkpal, K. C. Kocsis

"An underground environment with high air temperature and humidity conditions generated from various heat and moisture sources can significantly affect the thermoregulation processes of the human body. This can lead to a series of heat-related illnesses such as heat exhaustion, heat cramps and heat stroke. The majority of the metabolic energy of a mine worker results in the production of heat. If the human body is to maintain thermal equilibrium, then this metabolic heat must be transferred to the ambient surroundings at the same rate. The heat loss from the human body occurs through a combination of heat transfer processes, such as respiratory heat exchange, convection, radiation and evaporation. If the heat loss from the human body to the ambient surroundings is less than the metabolic heat produced, the excess will be accumulated within the human body, which will result in a rise in the core and skin temperatures. This can ultimately lead to a heat-related illness or a combination of heat-related illnesses. This paper aims to discuss major heat-related issues and provide an overview of various mine ventilation and cooling systems, which can be employed to overcome high levels of heat and humidity in underground mines. In this paper, the effects of heat exposure on the health, safety and productivity of the mine workers are also highlighted. IntroductionMining in the United States remains one of the most hazardous industries, despite significant reductions in fatal injuries over the last century (Coleman and Kerkering, 2007; Saleh and Cummings 2011; Jacklitsch, Musolin and Kim, 2016). Occupational health hazards within the mining industry include hazards that are physical, such as traumatic injury or hearing loss; chemical, such as silica or diesel particulate matter; biological; ergonomic; and psychological (Donoghue, 2004; Saleh and Cummings, 2011). The effects of some of these hazards can be diagnosed immediately, while many, like black-lung and silicosis, will have long-term effects on the health, safety and life quality of mine workers (Donoghue, 2004; National Institute for Occupational Safety and Health, NIOSH, 2000). Among these hazards, exposure to heat and humidity can significantly affect the safety, health and productivity of mine workers, particularly in deep and hot underground mines (Roghanchi, Sunkpal and Kocsis, 2015). Short-term acute heat exposures can cause a rise in the core temperature of the human body, which can result in a heat-related illness or combination of heat-related illnesses. Adverse long-term chronic heat exposure can generate serious occupational heat-related illnesses, such as cardiovascular diseases, mental health problems and chronic kidney diseases. High core body temperatures coupled with dehydration can generate negative behavioral effects such as physical fatigue, irritability, lethargy, impaired judgment, loss of dexterity and loss of concentration (Xiang et al., 2014)"

Jan 9, 2017

By R. L. Loofbourow

Reasons for reexamining underground mining include: 1. The assurance that more deep deposits of useful minerals will be found. 2. The existence of deeply covered deposits of industrial minerals near large markets where quarries are becoming depleted or are lacking. 3. Surface property values, zoning and other limitations on open pit mining. 4. Expectation that underground space will be increasingly used for transportation, power plants, storage and similar purposes. 5. The improvements which have been made in underground mining. During the last three or four decades many changes and improvements have been made underground. All underground construction and mining has benefitted to some extent but the effect on the productivity of labor employed with some methods- has changed little and the use of these methods has declined. Productivity of labor in other methods has increased substantially. The relative usefulness of mining methods has changed and a vital industry, bituminous coal, has been returned to health. In this paper, consideration is limited to nine methods used with high productivity during the period under review. These methods are not necessarily better than others but they may be considered the prime methods in the sense that, in our economy, many, low grade ores, coal and the principal industrial minerals could hardly be produced by less productive means.2 Although most of the examples cited are from mining as such., the first four methods discussed can be used for the construction of stable excavations of various&apos; shapes in sound rock.

Jan 1, 1967