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By Y. Luo

Based on the concept of slope stability analysis, a formula for determining an important parameter required in the mathematical model for the prediction of mining subsidence in hilly terrain has been proposed. The slope geometry and soil physical and mechanical properties of the surface natural slope can all be considered in the formula. Incorporation of this new formula into an existing mathematical model provides an integrated approach in studying ground movement in hilly regions.

Jan 1, 1998

By Juan L. Sepulveda

An MPSI KW-20 Tower mill has been tested at the Butte Molybdenum plant of Anaconda Minerals Company, as a substitute for the conventional 1.5x3.0 m (5x10 ft) tumbling ball mill currently used for regrind purposes. The Tower mill was operated in both open and closed continuous circuits. These results were complemented with a series of batch grinding tests to determine some of the operational features of this mill. The relative grinding efficiency of the Tower mill with respect to the tumbling ball mill was determined and the applicability of this new mill to a plant/heavy duty environment was assessed. Experimental results obtained on the regrind of moly concentrates indicate that approximately 40% energy savings can be realized by using the Tower mill instead of the ball mill.

Jan 1, 1984

By Alain A. Sonntag

The MBS Solvent Extraction System utilises a unique design of mixer- settler having very high capacity per unit area and great flexibility. The development of the mixer-settler is traced through its various stages wherein the independence of mixing and pumping, reduction in settler area requirements and simplicity of plant layout were achieved. The laboratory, pilot plant and full scale tests contributing to the development of the machine are described. The existing KREBS SX plants in Europe and Africa are described as well as the plants presently under design. Results of recent testwork are also given.

Jan 1, 1981

By D. L. Boreck

With increasing land development, the potential of fatalities from abandoned mine shafts increases. To minimize potential liability, shaft closure should be a critical part of mined land reclamation. The Bureau of Mines is conducting research into using lightweight foam concrete in sealing abandoned coal mine shafts. A demonstration seal consisted of a 3m thick foam concrete plug to provide lateral stability inside the shaft. A high density concrete cap provided load-bearing capacity for a 100-year service life. The USBM has also completed research into changes in foam concrete when it is pumped or dropped from different heights. It is concluded from the research that foam concrete can undergo significant air loss with pumping or dropping. This foretells significant changes in the characteristics of the concrete as well as an increase in the weight and cost of the in-place concrete seal. When using foam concrete to seal abandoned mine shafts, care must be taken to minimize air loss during placement.

Jan 1, 1994

By Clark Harrison

It is not uncommon for overall quality of coal from a mine to deteriorate as the mine is developed or for an improved-quality coal specification to be imposed during the life of the mine. Either of these conditions typically results in management pressuring mine personnel to take greater care in delineating the seam from top and bottom rock. When mining and seam conditions require a portion of the seam to be removed to ensure sufficient rock is removed to meet the quality specification, physical-coal cleaning may become economically competitive with in-pit seam grooming. The additional cost of coal cleaning may, in some cases, be justified by permitting higher recovery of the coal seam than is possible when cleaning the seam with excavators in the pit. This paper compares projected coal cleaning results with present in-pit grooming techniques and reports the economic results.

Jan 1, 1987

By J. J. Reilly

The Vesta Mines of the Jones & Laughlin Steel Corporation operate in the Pittsburgh Seam in Washington County, Pennsylvania. This seam is overlain with a drawslate, 12" to 16" in thickness, which slimes readily when wet. Because of the need for a uniformly good quality metallurgical coal, the amount of reject, together with the top and particle sizes of the raw coal feed, is a serious problem at the Vesta Preparation Plant. The Preparation Plant operates two, seven and one-quarter hour shifts per day and processes 2,100 tons per hour of raw coal feed. The third shift is, used for planned maintenance of equipment. Since the water clarification equipment is so vital in insuring a uniform product, there is no alternative but that it be in operation at all times. To insure this continuous operation,. well-planned maintenance is a necessity. For years, Plant Management has kept performance records of the various units to determine the renewal dates of vital component parts, the length of wear, the various materials used in the manufacture of the equipment, and the labor cost for renewal. These records have been of inestimable help in planning an effective maintenance program to insure continuous operation of the various units.

Jan 1, 1959

By Ekkehart Mertins, Hans-Dieter Wasmuth

During the last years many new concepts have been presented for magnetic separation of feebly magnetic minerals by using the new high-duty permanent magnetic material especially in Open Gradient Magnet Systems (OGMS). In this respect KHD Humboldt Wedag AG developed an improved version of a drum-type magnetic separator called PERMOS® with a special magnetic field configuration for the NdFeB permanent magnets, which gives a magnetic field strength of at least 0.7 Tesla and a wide working zone outside the drum. The magnet system within the PERMOS® unit is no longer made of relatively large magnet blocks of alternating radial magnetisation; the system is now made up of a multitude of small NdFeB bars with a specially oriented magnetisation. This PERMOS® Open Gradient Magnetic Separator can be used for dry magnetic separations in "top-feed" and 'free-fall" feed configuration as well as in the conventional wet "drum-type" feed mode. It allows high throughput rates of up to 40 metric tons of solids per hour and meter of drum length without any clogging problems, even when strongly magnetic com-pounds are present in the feed material. The important design features and the actual machine characteristics of the improved PERMOS® units for dry and wet magnetic separation are described and typical examples for their commercial application for industrial minerals and for martitic iron ores are presented.

Jan 1, 1995

By A. Arik

Reliable ore reserve estimates for deposits with highly skewed grade disributions are difficult tasks to perform. Although some recent geostatistical techniques are available to handle problems with these estimations, ordinary kriging or conventional interpolation methods are still widely used to estimate the ore reserves for such deposits. The estimation results can be very sensitive to the search parameters used during the interpolation of grades with these methods. This paper compares the ore reserve estimates from ordinary kriging using several cases in which certain search parameters are varied. The comparisons are extended to different mineralizations to show the changing effects of these parameters.

Jan 1, 1990

By C. R. Tinsley

In maybe the world's first in a mine project financing, a US $55 million Rehabilitation Indemnity was given on behalf of the banks in a US $250 million loan to develop the Ranger uranium mine, Northern Territory, Australia. The basis of the financing was an estimate of removal of the tailings and replacement into the pit. The Indemnity was amortized by a sinking fund from the mine's revenues. Such a concept could be valuable for mineral developments in sensitive areas or jurisdictions such as British Columbia or Alaska.

Jan 1, 1992

By D. Kang, K. N. Han

The adsorption behavior of silver in ammoniacal solutions on activated carbon was studied. In addition to the concentration of ammonia, the parameters that affect adsorption include temperature, degree of agitation and anion and cation concentrations. In the study, it was found that the adsorption of silver from ammoniacal solutions is dependent on the initial silver concentration in the solution. It was also found that the recovery of silver from ammoniacal solutions is not as effective us gold. The adsorption rate was relatively slow overall, despite a rapid initial adsorption. The apparent activation energy ,for the adsorption was measured at 30.2 kJ/mol. It was believed that the kinetics of the silver adsorption on activated carbon was limited by a mixed control mechanism.

Jan 1, 1999

By Herry Poernomo, Agus Prasetya, Iga Trisnawati, Himawan Tri Bayu Murti Petrus, Gyan Prameswara, Panut Mulyono

We studied yttrium extraction from untreated zircon sand processing waste tailings. Xenotime mineral as the rare earth element source with an abundance of yttrium (REY) was detected in sufficient grade for extraction. As much as 9.03% yttrium exists in zircon tailings (analysed by X-ray fluorescence spectrometry). The presence of yttrium was confirmed by X-ray diffractometry in xenotime minerals, which are yttrium carriers (Y-PO4). The purpose of this research was to determine the effect of leaching conditions on yttrium recovery from zircon sand after alkaline fusion treatment. Alkaline fusion was chosen to decompose phosphate into hydroxide in the xenotimemineral,which will reduce further required hydrometallurgical processing.Alkaline fusionwas carried out for 3 h at 450 °C, with a ratio of sodium hydroxide to zircon tailings sand of ~ 1:1. The alkaline fusion product was leached with water, followed by hydrochloric acid treatment to leach the yttrium. Yttrium recovery reached 87% under optimum conditions (60 °C, 1MHCl, and solid-to-liquid ratio = 1/10 for 7.5 min). A suitable model for yttrium dissolution with hydrochloric acid was diffusion through a solid particle ash layer. The calculated activation energy (EA) for this model was 20.21 kJ/mol.

May 26, 2020

By S. T. Hall

The authors have previously described a method of enhancing the magnetic susceptibility of pyrite by a mild alkaline oxidative pressure leach (Hall et al, 1985). This finding was successfully applied to enhance the magnetic desulfurization of an Eastern Canadian coal (Hall and Finch, 1984). This paper reports on enhancement of the magnetic susceptibilities of iron-containing sulfides (arsenopyrite, chalcopyrite and marcasite) upon similar treatment. It also explores the application of this pretreatment in the magnetic separation of fine sulfides from oxides and other sulfide minerals. In the latter case galvanic interference effects have a serious impact on the potential use of this method.

Jan 1, 1985

By R. R. Hall

Tests were conducted to assess the potential of column flotation for beneficiation of a talc ore from Montana. This ere contained approximately 80% talc, with the gangue comprised mainly of chlorite, silica, and dolomite. A tributylamine, MIBC, and sodium silicate reagent suite proved effective for talc flotation. Rougher-cleaner column flotation in a continuous open-circuit produced a final talc concentrate which contained 0.90% Al2O3. 0.17% CaO, and 1.28% Fe2O3. These analyses represented impurity rejections of 77, 85, and 65%, respectively. Weight recovery for this open-circuit was 52%; however, weight recovery was estimated to be 75% with cleaner tailings recycle. Results from this investigation show that column flotation is a viable means for beneficiating talc.

Jan 1, 1990

By R. Merkl

Since the 1940s, decanter centrifuges have become more important for increasingly complex solid-liquid or solid-liquid-liquid separation processes. Sometimes processed industrial or metalliferous minerals are abrasive or are treated with corrosive chemical agents. Traditional mining applications include the processing of coal, gravel and other products, where low-speed decanters, as well as screen bowl decanters and filters, dominate. These have been increasingly replaced by high-speed decanters during the last decade. Decanter centrifuges also started to play a key role in applications such as drilling muds, processing carbonates and separating SX crud in copper platinum ore concentrations of nickel and gold. Communication between machine producers and mineral processing engineers is vital for the right choice of materials and the design of the right decanter centrifuge for the individual process.

Feb 1, 2012

By R. Bhaskar

The objective of the project was to optimize the ventilation parameters of a continuous miner underboom scrubber to further control. the amount of airborne dust discharged during mining, to further reduce the exposure of face personnel for an exhaust brattice ventilation system, and avoid recirculation of contaminants at the face. This research was performed in an underground coal mine in Utah. The tasks included preliminary face ventilation evaluation and optimization of the scrubber system to eliminate recirculation of the scrubber discharge air. Airflow tests were conducted on the currently used dust control system and the modified scrubber system. Tracer gas tests were performed to evaluate face ventilation effectiveness. Confirmatory tests of the scrubber system under actual operating conditions, modifications to the scrubber system, and a comparative evaluation of the scrubber system vs. the existing system were performed. This paper presents the results of the airflow pattern tests and the respirable dust levels in the modified scrubber system and the existing system. The optimized face ventilation parameters and the developed operating guidelines may provide the benefits of dust reduction, better face ventilation, and improved visibility.

Jan 1, 1994

By Dwayne C. Kicker, Duk-Won Park

As the use of longwall mining increases in the U.S.. there is a need to better understand the stress redistribu- tions indicative of this method. To control high stress concentrations, the yield pillar concept has been developed. A physical longwall mine model has been designed to study the effect of yield pillars in deep mining. The model in- cludes sensitive stress measuring devices, a new excavating technique, and a new model material. This study includes the use of both regular and yield pillar systems and has successfully simulated the mode of stress change in chain pillars.

Jan 1, 1986

By Donald E. Warnken

The Study concerns the estimation of fair market value (FMV) of non-producing mineral rights. Two approaches to value are used and the values determined by each are compared. The Study area environment is unusual. The tectonics is visible on surface rocks throughout much of the study area. The effect on mineral values in the exposed areas has been compared to areas where the tectonics is not visible.

Jan 1, 2005

By C. C. Clark

The National Institute for Occupational Safety and Health (NIOSH), Ground Control Engineering Branch is investigating the use of shotcrete in weak rock mass mines with the objective of reducing fatalities and injuries resulting from rock fall accidents. When shotcrete is used as part of a multi-element ground support system there is a need to know when the material has developed a threshold early compressive strength of approximately 1 MPa (145 psi) for safe re-entry of miner and machine into shotcreted mine workings. This equates to the material having developed enough strength to be self-supporting and allow for emplacement of the remaining support elements that require drilling of the shotcrete layer without degradation. NIOSH researchers have developed methods and portable test equipment to measure shotcrete strength on-site in the first six hours after application using the ASTM C 116-90 (1990) standard. These advances were demonstrated in tests on five commercially available shotcrete mixes, sprayed as dry shotcrete using the field expedient methods and equipment. The strength values from these tests allowed for real-time identification of the early strength threshold and were consistent with strengths reported using laboratory-type equipment. The findings of this NIOSH research for determining shotcrete early strength can improve mine safety by providing a method for determining initial site specific material property values to be used for design and as a means to conduct on-site quality control and monitoring during production.

Jan 1, 2010

By R. K. Mensah-Biney, M. T. Hepworth, K. J. Reid

The loading characteristics of gold-bromide species onto activated carbon were evaluated using a batch system. The overall loading of gold onto activated carbon was rapid for the first few hours, but it continued without cessation as a result of the reduction of gold. Therefore, conventional equilibrium considerations were not applicable. Although loading continued slowly after several days, an abnormally high, loading capacity value of 10-12 meq/g carbon (650-800 kg Au/t) could be attained in 72 hours. The loading of gold-bromo species by activated carbon was by the mass transfer of (AuBr4)- species to the external surface to be reduced to metallic gold by carbon. Elution of gold from loaded carbon was feasible provided the carbon had not been loaded to high capacity values. If loading is carried to high levels, complete elution becomes impractical, and the gold may be recovered by ashing the carbon. For the high loading capacities observed, this option would appear to be cost effective. The effect of several variables on the loading capacity of the activated carbon for gold-bromo species is discussed.

Jan 1, 1994

By H. EI-shall

In this paper, the results of bench scale testing of five different flotation processes to separate dolomite from phosphate are discussed. The effectiveness of each process interms of phosphate recovery and MgO content in the concentrate is used together with the reagent consumption as the basis of comparison. The water quality is found to play a major role in the performance of these processes. Effect of water hardness as well as other parameters are discussed.

Jan 1, 1995