Search Documents

By S. J. Schatzel, V. Gangrade

A ventilation research study was conducted by the U.S. National Institute for Occupational Safety and Health (NIOSH) and a cooperating longwall trona mine in the Green River basin of Wyoming in the United States. The objective of the study was to evaluate the movement of longwall face air and exchanges between the face and worked-out areas to document the presence or absence of face airflow pathways between these locations. Tracer gas experiments using sulfur hexafluoride (SF6  ) were conducted to describe air movement on the face and in the mined portion of the active panel. Maintaining adequate ventilation air on longwall faces is important for worker safety and for the dilution of gases emitted from the face and caved gob.

By Sean Dessureault

The mining industry has used fleet management systems (FMSs) for decades. These systems were developed long ago in large truck-and-shovel mines, where hardware sales were the core business driver for vendors. These traditional models can be overhauled in the era of the Internet of Things (IoT), Big Data, gamification and low-cost tablet technology. Relatively low-cost tablets are ubiquitous in modern life, and they are packed with communication radios and sensors like Global Positioning System (GPS) and inertial measurement units used widely for games, fitness measures and navigation. These powerful computer devices provide the same, if not more, sensing capability than traditional fleet management hardware, all at a fraction of the cost and without complicated cables or challenging supply lines. 

By A. M. Johnson

Although known primarily for native copper, the Keweenaw Peninsula of northern Michigan also has deposits of copper sulfide (chalcocite) ore. A number of small, but rich, deposits are present at relatively shallow depths near the base of a thick, steeply dipping sequence of volcanic and sedimentary rocks. Because much of the ore is fracture-controlled, the deposits appear to be ideal candidates for in-situ leaching. Fracture mapping from drill core and borehole logs coupled with borehole packer permeability tests are being applied to evaluate the suitability of the ore for in-situ leaching. A leaching scheme utilizing a bacterial-assisted ferric iron lixiviant is being tested at bench scale. A pilot scale test is being designed to evaluate the system in the field.

Jan 1, 1988

By Michael J. Virnig, Kathryn C. Sole, Murdoch W. MacKenzie, Michael R. Davis

A solvent-extraction process has been developed for the removal of copper cyanide complexes from aqueous copper/gold cyanide solutions formed in gold-recovery circuits that treat ores containing cyanide-soluble copper. The process uses LIX® 7820, one of the LIX® 7800 reagent series developed by Henkel. It is based on a mixture of Aliquat® 336, a quaternary amine, modified with an alkylphenol, 4--nonylphenol. Extraction and stripping data for the base metal cyanides and thiocyanate are presented. Methods for the recove1y of copper and cyanide from the upgraded strip liquor are reviewed. A flowsheet based on this chemistry and a preliminary economic evaluation of a solvent-extraction circuit combined with the cyanide-recovery process developed by Metallgesellschaft Natural Resources (MNR) are also presented.

Jan 1, 1999

By S. Duyvesteyn, L. Enloe, P. A. Schmitz, W. P. Johnson

The characteristics of gold leaching from carbonaceous matter by sodium cyanide, and sorption of gold cyanide to carbonaceous matter in autoclaved and non-autoclaved gold ore from Barrick Goldstrike Mines Inc. (BGMI), Nevada, was investigated. Much greater gold cyanide complex sorption was observed for the carbonaceous matter in high preg-robbing ores relative to the low preg-robbing ores. This observation corroborates previous reports that have attributed observed preg-robbing behavior to the carbon in the ore. Gold cyanide complex sorption was found to be reversible for carbonaceous matter from low preg-robbing ore, but was irreversible for carbonaceous matter from high preg-robbing ores. Autoclaving the ore appeared to enhance the sorptive behavior of the carbonaceous matter from both high and low preg-robbing ores.

Jan 1, 1999

Magnetic separators are commonly used as an effective and low-cost method to concentrate paramagnetic or ferromagnetic minerals. These versatile separators are often used in multistage circuit configurations to further improve concentrate recovery and/or grade. Although these circuits are generally very efficient, field studies suggest that the layout of multistage circuits can be less than ideal for many industrial operations. To illustrate this shortcoming, a theoretical analysis has been conducted to compare different circuit configurations for magnetic separators. The resulting knowledge base has been used to establish generic engineering guidelines for the layout of multistage circuits. The potential improvements in separation efficiency that may be realized through the application of these guidelines have been demonstrated using a simple case study.

Jan 1, 2004

By M. Khandrika, B. K. Parekh

Column flotation has proven to be the most effective technique for the flotation and recovery of ultrafine coal. The commercial application of columns in the coal industry is steadily increasing (Parekh et al., 1990; Yoon et al., 1992). For the flotation of coal or mineral air is used for generating bubbles. Using a conventional flotation cell, Miller and Mishra (1985) compared froth flotation behavior of fine coal using air, nitrogen and carbon dioxide gas. They concluded that carbon dioxide gas provided a higher rate of recovery and a lower ash content. The objective of the present study was to investigate the effect of various gases such as compressed air, nitrogen, argon, and carbon dioxide on the column flotation of fine coal.

Jan 1, 1999

By W. Hennig

Efforts to define sustainability indicators are continuing in the mineral extracting industry and sector research institutions. Comprehensive ‘sets’ of economic, ecological and social sustainability indicators for the minerals industry are a necessary precondition for rationale-based negotiations with stakeholders from society. These tools alone, however, will not suffice in a delicately balanced economy-ecology -social well-being equilibrium with ever shifting valuation of different variables. Individual interests and emotions and also ideologically motivated positions of diverse stakeholders are gaining momentum. The minerals industry therefore has to develop beyond the rational pro-arguments for mining in the form of sustainability indicators also proactively its ‘soft skills’ to deal with expectations, fears and outright anti-mining bias, if it wants to retain the ‘social licence’ to continue.

Jan 1, 2005

By A. K. Bakshi

In cold regions, rinsing of spent cyanide from leach heaps is stopped during winter and is resumed again after the snow melts. The effect of this idle time on the overall removal process was studied in this experiment. Samples were collected for rinsing tests from one heap at a gold mine near Fairbanks, Alaska. Continuous and interrupted rinsing of this sample were carried out in test columns. The rinse solution was analyzed at regular intervals to determine the rate of cyanide removal from the solids. It was found that total cyanide concentration per rinse cycle for interrupted rinsing test was higher than for the corresponding continuous rinsing test. As a result, interrupted rinsing required less rinsing cycles than continuous rinsing.

Jan 1, 1995

By F. -U. Schneider, F. Wellenkamp

Based on previous investigations of ultrafine comminution in planetary ball mills, a new centrifugal mill has been developed which permits similar high stress conditions. Because this new type of mill is equipped with an immobile chamber, devices for measuring energy, for cooling the milling vessel, as well as, in continuous operation, for material feed and discharge can be more easily attached than to planetary ball mills. Observations of particle behaviour have shown that, in the case of dry grinding, most of the material is found on the mill walls even after short grinding times. Due to the fact that energy dissipation takes place mainly in the zone near the wall, a grinding system which reduces the amount of ball filling required is at an advantage.

Jan 1, 1995

By S. Eugene Sankey, Geoffrey L. Payne

Fundamental choices in flocculant selection often come down to the lower cost of solid grade products versus the convenience of liquids. The ideal product would be a low cost solid grade flocculant which requires minimal handling and no sophisticated dissolving equipment. Recent polymer developments have lead to the commercialization of a limited range of dry polymers that can be screw fed at controlled rates directly to process streams without the need for predissolving. Other developments include dry polymers that can be directly added to mix tanks without the need for sophisticated wetting systems. The latter will make dry flocculants especially attractive for smaller users. Examples of these new products and their application in industrial and municipal waste treatment will be provided.

Jan 1, 1994

By John D. Nelson, Clint L. Strachan

Drainage of tailings impoundments is a key issue for impoundment stability, water control, seepage control, and reclamation. Drainage control is an established operating practice where climate and site conditions permit, such as in South Africa and various mines in North America. In these areas, drainage control is primarily used to maximize tailings densities and to provide adequate impoundment stability. Drainage practices during operation also become an important issue when tailings impoundments are reclaimed. Time required for cover placement and post- reclamation seepage control depends greatly on the ability for tailings to drain and consolidate. This paper discusses drainage issues associated with gold tailings impoundments in terms of mechanics of saturated and unsaturated flow and experience with design and reclamation of tailings impoundments.

Jan 1, 1988

By B. M. Moudgill, T. V. Vasudevan

Marine sedimentary deposits account for 80% and igneous deposits 17% of the total world output of phosphate rock. The phosphate mineral is well crystallized and exhibits a greater floatability in the igneous deposits than the sedimentary ores. Both silicates and carbonates contribute the major gangue associated with the sedimentary ores. Although removal of silica from sedimentary phosphates by froth flotation has been in practice for several decades, with the depletion of high-grade reserves, new attempts are being made to improve the efficiency of current silica removal technology and to develop new processes for beneficiation of phosphate ores associated with the carbonate gangue. In this paper, recent developments in processing of sedimentary phosphate ores containing carbonate and silica gangue are discussed.

Jan 1, 1987

By Michael E. Mcllwain, Lee O. Nelson, Robert D. Rogers, James H. Wolfram

Examination of the economics and environmental consequences associated with phosphate fertilizer production documents the necessity for development of innovative production technologies. Evidence of phosphate ore's susceptibility to microbial alteration indicates that it will be an ideal candidate for industrial-scale bioseparation. There are at least two applications for the biosolu- bilization technology: (1) an industrial-scale bio- process similar to the presently used wet acid process and (2) production of small prills (bio- bead) containing unprocessed rock phosphate and the biological ingredients necessary to promote phosphate solubilization. At the present stage of development, the biobead technology is the preferred application. It is an energy-efficient "green" technology that will dramatically reduce the amount of solid waste and air emissions produced by the phosphate industry.

Jan 1, 1999

By R. Gong, R. Bhaskar

The development of a three-dimensional mathematical model for evaluating airflow fields at a continuous miner face is described. The model utilizes three-dimensional incompressible flow, mass continuity, and momentum (Navier-Stokes) equations to predict the airflow velocity at the face. Obstacles and equipment in the face area are modeled using appropriate boundary conditions. Parameters such as flow velocity and face dimensions can be modified and evaluated for various schemes, such as exhausting and blowing ventilation, using either brattice or tubing. A model such as the one described, with additions for local effects, can be used to evaluate novel face ventilation ideas before initiating expensive full-scale tests or field studies. The model described is a step in the direction of advanced predictor models.

Jan 1, 1993

By Richard L. Ranich, Frank F. Aplan, J. B. Hiskey, Robert S. Thompson, B. J. Scheiner

Acidic waters typified by acid mine drainage, copper dump leach solutions and steel pickle liquors will typically contain SO4-2 and cations such as Fe+3, AI+3 and for the pickle liquors, sometimes Cr+3. These acidic waters will often react with limestone, present naturally or introduced for purposes of solution neutralization, to form reaction - inhibiting coatings of gypsum and gelatinous, metal hydroxide precipi¬tates. The coating thickness, as a function of pH, was quantified for both reactive (calcite, limestone) and non-reactive (quartz, barite, fluorite) minerals, and the data were related to the hydroxy species diagrams and to solution turbidity measurements. Coatings were found on the reactive minerals at a lower bulk solution pH than on the non-reactive minerals.

Jan 1, 1993

By L. Xu, R. Bhaskar

While a NIOSH accepted procedure exists for determination of quartz in the respirable dust samples from coal mines, no specific procedure has been defined for quartz determination in bulk samples. In this study, the effect of particle size on the estimation of quartz using the infrared technique was evaluated. Several laboratory tests were performed to determine the dependence of the infrared absorbance peak height on the different sizes of quartz particles. The significant dependence observed between quartz particle size and the measured peak height indicates the potential for erroneous interpretation of the quartz in bulk samples depending on how the samples are prepared. A procedure to reduce the effect of size in the determination of the quartz content is suggested.

Jan 1, 1994

By J. K. Mokka, P. D. Rao, H. K. Lin

Extensive exploration has resulted in delineation of a massive sulfide district on the north flank of the east-central Alaska range. The district covers approximately 400 mi2 and contains numerous stratiform, transposed and some replacement type sulfide deposits ranging in size from less than 1 million st to 20 million st. Five types of ores were sampled for the study. Mineralogical analysis revealed that the minerals are too fine grained for conventional grinding and beneficiation. Hydrometallurgical studies were conducted using ferric chloride as a lixiviant. Ore microscopic studies as well as electron microprobe analyses of minerals in the raw samples and leach residues explained the low recoveries for certain elements as well as sources of impurities that need to be eliminated from the process streams.

Jan 1, 1992

By George H. K. Schenck

Decisions to develop deposits of calcareous materials for cement production are based largely on anticipated markets for heavy construction which utilizes concrete. The geologist should understand the fundamental factors that underlie such management decisions, so that his field work and reports will more effectively relate to the information requirements of managers in the cement industry. The paper examines the relationships that exist between exploration and development of calcareous raw materials for cement manufacture and changing factors in the marketing of cement. Continued overcapacity, improved technology, changing distribution patterns, ease of entry, economics of scale, and the nature of product demand are some of the characteristics of the cement industry that are basic to decisions regarding exploration programs and property development.

Jan 1, 1966

By Tetevi B. Wilson

Analysis of the distribution of ore-bodies in space can be useful generally in the estimation of mineral resources or the management of exploration. This study is di¬rected to analysis of the undiscovered potential of well known areas of mining district size, referred to as metallogenic units (MUs). The analysis employs an effort¬ adjusted and truncated probability model for number of occurrences within a subdivision (quadrat) of a MU and Monte Carlo sampling to generate an approximation to the probability distribution for number of occurrences and number of mines within an MU when it is totally explored. Exploration potential for Monitor, Bodie, Au¬rora and Camp Douglas MUs (Walker Lake quadrangle of Nevada and California) are estimated to be 9, 4, 7 and 4 mines, respectively.

Jan 1, 1992