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By J. W. Langhans, B. D. Blake

The U. S. Bureau of Mines has been investigating the application of thiosulfate to recover gold directly from low grade refractory carbonaceous ores for the past four years. Statistical experimental methods were used to determine the effects of various leaching parameters on both gold extraction and thiosulfate consumption. Seven variables were investigated, including thiosulfate, copper, ammonia, sulfite, and sulfate concentrations, leaching time, and leaching atmosphere. This information was used in face-centered cubic (FCC) surface response experiments to define the optimum leaching conditions for a low grade ore. Two models were generated from the data to predict gold extraction and thiosulfate consumption as a function of the leaching parameters. The models predicted a gold extraction of 67 pct and reagent consumption of 2 kg [S2032/mt ore at 0.25 M S2032-, 0.0014 M Cu2+, 0.27 M NH,OH, 0.00625 M SO;-,] and leaching for 16 h. Actual tests resulted in 62 pct gold extraction with 0.93 kg S2032- consumed/mt ore. Subsequent column leaching tests have further demonstrated the viability of applying this technology to recover gold from carbonaceous ores without first pretreating the material. Gold extractions in the column tests ranged from 69 to 78 pct with thiosulfate consumption ranging from 0.4 to 5.4 kg/mt ore. These results compare to <5 pct gold extraction using standard cyanide leaching conditions.

Jan 1, 1996

The US Geological Survey (USGS) held a one-day workshop at its Denver, CO facility to inform the public of the status of its National Mapping Program. In addition, the agency wanted to obtain information from topographic map users on what their needs are. The agency wants to know what the topographic map user wants. The USGS faces the challenge of keeping up with the changing needs of the nation. In the last few years, the agency has changed dramatically to meet these needs. For example, the "new" USGS incorporates mineral-information specialists from the former US Bureau of Mines and also uses the expertise of former National Biological Service employees. These areas complement the agency&apos;s traditional strengths in mapping, geology and water re- sources. The stated mission of the USGS&apos;s National Mapping Division is to "meet the nation&apos;s need for basic geospatial data, ensuring access to and advancing the application of these data and other related ears science information f& users worldwide." To accomplish this goal, the USGS publishes topographic maps, including shaded-relief editions of areas of special interest (state maps and national parks); photo image maps; satellite image maps; geologic maps and hydrologic maps. The geologic maps include geologic quadrangle maps, oil and gas investigation maps and charts, and coal investigations maps. The familiar 7.5-minute series topographic maps are the most widely used. The 7.5-minute- (1:24,000-scale-) format mapping was begun in 1935.

Jan 1, 1998

The world&apos;s largest hydraulic excavator was recently introduced at Syncrude&apos;s North Mine at Fort McMurray, Alberta, in Canada. O&K&apos;s 826t (910-st) behemoth RH400, with a 42-m3 (55-cu yd) bucket, is capable of loading 72.5 t (80 st) in one pass. Syncrude&apos;s Alberta operation is the nation&apos;s largest single source of crude oil. It is also the world&apos;s largest producer of oil from oil sands. Syncrude produces 205,000 bbl/day, expects to increase production to 225,000 bbl/day by 1999 and to 320,000 bbl/day by 2005. That translates to 73.5 million bbl of Syncrude Sweet Blend (SSB) produced in 1996, 82 million bbl in 1999 and 114 million bbl in 2005. The North Mine is a new development that will replace the current East Mine, to be depleted of oil sand by the end of 1999. The North Mine will feature hydrotransport, a new and unique method of transporting oil sand from the pit to the process plant. Oil sand from the truck-and-shovel operation will be processed through a double-roll crusher and placed in a cyclofeeder where it mixes with hot water. The material is then screened and transported by pipeline to the extraction plant. Hydrotransport will replace conventional conveyor transport for moving raw product from the pit. Mine development will also use two 290-t (320-st) haul trucks to compliment the fleet of existing 218-t (240-st) trucks.

Jan 1, 1998

By Byron N. Cooper

The Revenue Act of 1926 provided for five simple categories of natural resources to have the benefit of depletion allowances. In the 1947 Revenue Act, the number was increased to twenty-five, and in the 1951 Revenue Act to fifty-four. Of this number, fourteen were allowed 5 per cent; nine, 10 per cent; twenty-nine, 15 per cent; one, 23 per cent; and one (oil and gas), 27.5 per cent. The 1951 Revenue Act created a host of difficulties, including application of the "end- use criterion" and determination of the commonly accepted meaning of such terms as limestone, dolomite, chemical- and metallurgical-grade limestone, marble, calcium carbonates, and magnesium carbonates. Dolomite, for example, was listed at 10 per cent depletion allowance, but without definition. In the great amount of litigation growing out of the 1951 Revenue Act and its administration, it became essential to understand the derivation and subsequent usage of these common geologic terms. One thing that became clear was that our definitions changed significantly between the time that the 1951 Revenue Act became law and the time that later cases were tried. Some geologists neglected to learn about first usages of such terms as metallurgical limestone, and about meanings that were applicable when the 1951 Revenue Act was written and passed. Legal meanings in this paper are discussed in the light of certain famous cases that have been tried and settled.

Jan 1, 1966

By K. C. Vories

Surface mining and reclamation has the potential to at least temporarily increase surface runoff and resultant erosion and gully development. This increase in erosion is due in part to compaction of the soil surface with heavy equipment, creation of large relatively unvegetated watersheds, and elimination of natural dendritic ephemeral drainage patterns. Methods for stabilizing gully channels which may develop prior to establishment of sufficient vegetation to control erosion are analyzed. Utilization of various sizes of riprap for channel lining, the use of riprap check dams, reinforcement of riprap check dams, and the relation- ship of type of control structure to area of watershed and resultant flow velocities are discussed.

Jan 1, 1986

By M. Makarenko

The sandstone type Devladivske uranium deposit is located within the limits of Eocene pale-ovalley filled with alluvial sediments. Mineralization with uranium content up to 0.1% forms several ore beds divided by redox barriers. In the period 1962-1983 the deposit has been exploited over an area of 918000m2 by in situ leaching (ISL) using drillholes with a depth between 35 and 100m. During mining operation about 200,000 t of H2SO4, 6,300 t of HNO3, and 15,000 t of NH4NO3, have been pumped in the ore body. In 1983, the groundwater pollution aureole had a length of 4.5 km and a width of 400-600 m. There is a hydraulic connection between the uranium-bearing aquifer and both the upper and lower ones. The technological solutions used for ISL caused partial contamination of these horizons. After mining completion, dilution of the residual technological solutions with "pure" natural waters took place through gaps in impermeable sediments between aquifer horizons. Calculation of self-purification process kinetics shows that the sulfate ion pollution aureole will disappear approximately after 120-150 years at a distance up to 2.0-2.5 km from the western margin of the deposit. This means that there is no risk for contamination of the river Saksagan? that flows at a distance of 17km from the deposit.

Jan 1, 2005

By D. K. Jorgensen

The Bullfrog and Montgomery-Shoshone deposits, near Beatty, NV, have a combined drill-indicated reserve of 15.8 Mt (17.4 million st) of ore. Average grade is 3.5 g/t (0.103 oz per st) gold and 8.2 g/t (0.24 oz per st) silver. The deposits occur in Miocene volcanic rocks that underwent large-scale movement within a detachment-faulted terrane. The principal host to gold mineralization is a strongly welded rhyolitic tuff that experienced brittle deformation during plate movement. Open space fractures and breccia were filled with quartz, calcite, and adularia accompanied by lesser pyrite, gold, and acanthite. Gold occurs as micrometer-sized particles within and adjacent to the low-angle fault and along associated listric-normal and tear faults. The Bullfrog and Montgomery-Shoshone are volcanic-hosted, detachment fault-related, epithermal quartz calcite stockwork gold deposits. Bullfrog&apos;s minable reserve is 13 Mt (14.3 million st) of ore grading 3.8 g/t (0.11 oz per st) of gold. At Montgomery-Shoshone, 2.7 Mt (3 million st) minable tons at 2.5 g/t (0.072 oz per st) are present. Preproduction stripping has begun at the Bullfrog ore body. A 7.7-kt/d (8500-stpd) carbon-in-pulp (CIP) mill is under construction. In 1990, Bond Gold expects to be producing about 6.2 t/a (200,000 oz per year) of gold.

Jan 1, 1990

By Z. D. Yu, J. E. Gebhardt, D. I. Phillips, S. X. Jiang, R. Z. Zhang

The potential application of flotation for the treatment and processing of a fine-particle coal stream was investigated for the Chaili Coal Washery of the Zaozhuang Coal Mine Administration, Shandong Province, China. A goal of the test work was to evaluate the application of the Microcel™ flotation column and compare its performance to conventional flotation. Small-scale flotation tests were performed in the laboratory and on-site with fine coal slurry samples from the plant thickener underflow, i.e., the washing plant&apos;s undersized reject material. Flotation tests were conducted on-site with a 7.6-cm diameter Microcel™ column and with small-scale conventional cells. Column flotation tests were performed to determine a recovery-grade relationship for the fine coal feed, which contained about 24% ash, and to obtain sufficient data to enable scale-up to a large diameter unit. A primary objective as to establish the maximum throughput capacity of a Microcel™ flotation column while operating to produce a clean coal product with ash content of 7.5-7.8%. Results of the test work indicate that this product quality could be achieved at feed rates of 15-19 tph to a 3-m diameter Microcel™ flotation column. Lower ash products, i.e., 5-7% ash, were obtained but at lower column throughput capacities. Comparative flotation tests, conducted with conventional flotation cells, indicated that a product ash of only 8% or greater was achieved in a single-stage test.

Jan 1, 1995

By R. H. King

The US coal industry has been using continuous room-and-pillar mining (CRPM) machines for more than 30 years for longwall development. This equipment has also been used for production mining in areas that are not appropriate for longwall mining. From 1977 to 1987, the portion of annual US production mined by continuous miner (CM) sections grew slightly from 65% to 70%. Over this time, mine operators and manufacturers have made some advances to attain the full production potential of this method. This is evidenced by the fact that average tons per eight hour shift for continuous miners in the US grew from 180 t (200 st) in 1977 to 431 t (475 st) in 1987. The authors (1990) reported that the increase in productivity was due to several factors: • a drop in prices; • a more mature workforce; • union stability and incentive programs; •procedural improvements; and •technological advances. The authors estimated that about one-third of the increased production came from the first three and other unaccounted for factors and one-third each for the last two. Even though improvements were considerable, continuous miner capacity is much higher than 431 t/shift (475 st per shift). For example, the machinery is capable of mining more than 9 t (10 st) per machine for the 6.5 available hours per shift or 3.5 kt (3900 st). However, this has never been attained on development. The averages of most mines are less than 900 t/shift

Jan 1, 1991

By N. S. P. Kumar

INTRODUCTION Development work at Carr Fork Mine of Anaconda Copper Company in Tooele, Utah commenced in August 1974. A decision to install an underground gyratory crusher for primary crushing run-of-mine ore and waste was made in 1976. Higher throughput rates, larger reduction ratios and greater flexibility in terms of meeting immediate and expanded production needs were the main reasons for selecting the gyratory crusher over the jaw crusher. UNDERGROUND MATERIALS HANDLING Underground crushing and conveying system was designed for a capacity of 16,300 mtpd of ore and waste on a 2-shift, 5-day week basis. Engineering and design of crusher complex was performed by Anaconda engineers at Carr Fork. Figure 1 represents the longitudinal section of mine showing the general materials handling system. Mine area is trackless except for materials and production haulage which is run on rail track on both 1200 and 970 levels. Ore from stopes and waste rock from development headings are handled by 3.8 cu m (5 cu yd) Jarco scoops and dumped into 2.4 m (8 ft) diameter ore and waste passes at the 1200 level. The material gravitates down to the 970 level where it is loaded into 12 cu m (420 cu ft) ASEA mine cars using side loading chutes. The muck train, consisting of 15 to 18 cars and two 27 mt General Electric trolley locomotives, is hauled over a distance of 2,300 m (7,550 ft) to

Jan 1, 1981

By V. A. L. Breguncci, A. H. Martins, C. P. Ribeiro Jr.

This work presents experimental results for the recovery of gold present in alkaline cyanide solutions by using the electroelution technique of strong-base anionic polymeric resins IRA 402-CL from Rhom and Haas-Brazil Ltd. loaded with gold. This technique of electroelution of anionic polymeric resins is based on the removal of metal ions adsorbed to the resin, resulting from a potential difference applied between the cathode and anode in an electrolytic cell. The electrolytic cell was composed of an aqueous solution with suitable chemical characteristics and an anionic polymeric resin bed loaded with gold. The resin used in the experiments was loaded using synthetic alkaline gold cyanide solution with 1.0 g/L of gold. The variables studied were electroelution time, cathode current density, distance between cathode and anode and the electrolyte chemical composition. Statistical methods made it possible to establish the optimum conditions that would achieve satisfactory gold recoveries by the electroelution technique. The statistically predicted response for the resin loaded with gold by percolation was 16.5% gold recovery, 2.0 A/m2 cathode current density, 20-mm distance between electrodes and 6.0 hrs electroelution time. For the centrifuging system, the statistically predicted response was 7.41% gold recovery under the following conditions: 0.25 A/m2 cathode current density, 1-mm distance between electrodes, 3.5 hrs electroelution time and 10.9% NaOH in the electrolyte chemical composition.

Jan 1, 2002

By J. J. Schwoebel

Resource Enterprises, Inc. (REI) is exploiting the coalbed gas resource by working in unison with active underground mining operations. At REI?s pilot project at the Soldier Canyon Mine, Carbon County, Utah, REI has drilled nearly 15,250 m of horizontal in- seam and slant boreholes during the initial two years of drilling activity. Produced gas has been sold to a natural gas transmission company on a continuous basis since mid 1983.

Jan 1, 1986

By J. Van Kleunen

In the Spring of 1959 the Riverside Cement Company, a Division of American Cement Corporation, placed into operation at their Oro Grande California plant a new crushing-blending-reclaiming facility. This new facility, in conjunction with other modernization in the plant, has established a degree of automation and reliability on a-plant-wide basis which heretofore had not been attained in the industry. The blending and reclaiming facilities for raw stone and cement clinker at this plant represent not only the first computer programmed materials handling system of its type in the industry, but also the first installation of specialized equipment which was designed for high capacity, fully automated operations.

Jan 1, 1963

By G. Blackwell

In the 1980&apos;s the Canadian surface mining industry was confronted by declining competitiveness in the face of low cost foreign producers and alternative materials. Low metal prices undermined profits for many mining companies. Restructuring, rationalization, capacity reduction, technology transfer, as well as favourable currency rates and higher commodity prices, helped revitalize the industry by the close of the decade. Now in the 1990&apos;s, however, the need to improve competitiveness for profitability has re-emerged in greater intensity. In the current climate it is considered that there are three strategies available to industry to ensure profitability: continued rationalization and restructuring; optimization of operating practice; and technology development and transfer.

Jan 1, 1993

By Earl Parker

The mining/mineral processing industry constantly faces the challenges of handling tons of material in a variety of processes such as crushing, milling, drying, belt transfer and loadout. These processes result in the production of high volumes of dust. A variety of dust detection and collection equipment is needed to properly manage these emissions to remain compliant with stringent air quality and safety requirements. Dust monitoring and bag leak detection can provide ways to reduce air pollutants, make work environments safer and remain compliant with requirements from the U.S. Environmental Protection Agency (EPA), U.S. Mine Safety and Health Administration (MSHA) and U.S. Occupational Safety and Health Administration (OSHA). There are several approaches to monitoring particulate emissions from dust collection equipment. These can include visual inspections, differential pressure gauges or bag leak detection systems. Bag leak detection and monitoring systems can be optical, light based or electrostatic/triboelectric. Recent developments have advanced the efficiency and reliability of electrostatic/triboelectric style monitors. New technological improvements have been developed that are based upon the principal of unifying dc (impaction) and ac (induction) signals and incorporating other proprietary circuit innovations. This higher signal resolution technology results in a more robust and stable measurement for detecting the presence of particulate in a dust collector emission duct or a flow process pipe.

By William Gleason

"Once the primary fuel source for the United States and the economic backbone for communities from Appalachia to Wyoming, coal has been on a steady decline since the mid 1990s, and is now at the center of political debate in the United States.The political spectrum of the United States is divided on the future of coal and its place in the energy sector. The coal mining industry and the communities that rely on coal have increasingly been pitted against forces that wish to regulate coal to the history books.In 2008, President Obama launched what many have called his war on coal, and during his eight years in office, he pushed through numerous pieces of regulations and legislation and that he said were aimed at reducing carbon emissions, but that others viewed as direct assaults on the domestic coal industry. Obama led the United States delegation to Paris to sign the Paris Accord in 2016, a 196-country agreement pledging that the United States would do its part to reduce carbon emissions. His administration also instituted clean air, power and water regulations that added extra environmental burdens to many industries, but perhaps none more so than the coal industry.In this month’s lead feature, “A study of U.S. coal mine closures since 1994” (page 18), the impact of the war on coal, and other factors, can be seen in text and figures. Author Jacob Brinkman and coauthors Jay Schafler and Catherine Johnson scoured the data of the U.S. Energy Information Administration (EIA) and the U.S. Mine Safety and Health Administration (MSHA) to show how coal production and mines have been impacted since 1994 and how the years 1994 to 2000 and 2008 to 2016 were particularly hard on the industry.For example, in 1994 there were 2,354 coal mines in the United States. Currently, there are 1,035 mines in operation.In 2016, then candidate Donald Trump promised to end the war on coal and to put coal miners back to work. In 2017, President Trump has followed up on those promises. He announced plans to withdraw the United States from the Paris Accord, signed an executive order designed to undo the Clean Power Plan put in place by President Obama, halted the research on the health effects of mountaintop removal coal mining, directed the U.S. Environmental Protection Agency (EPA) to revise the guidelines of waste water from power plants and has touted that more than 1,000 coal miners have returned to work since he was elected."

Jan 9, 2017

By L. L. Lien

In this economic age of high interest rates and softening mineral commodity markets, the mining industry is taking a hard look at how it conducts its business and where economies can be effected. The capital investment to build a new metallurgical facility or open a new property has traditionally attracted substantial investigation, analysis and management attention. The areas of mineral exploitation, financial feasibility, engineering and construction have been studied extensively and their management, although still difficult, have become refined disciplines.

Jan 1, 1982

By Harry M. Parker

Exploration for sandstone-type uranium ore bodies which will be exploited using underground mining techniques is usually executed in sequential fashion. Geostatistical methods can be used at the earliest exploration stages to design drilling programs which have a high probability of success in the location and delineation of mineable ore-grade mineralization, should such mineralization exist. In succeeding development stages, geostatistics may be used to outline and define the potential grade of reserves and to apply confidence limits on the grade estimation. Delineation of mineable reserves for mine planning requires extensive development drilling; using such drilling data geostatistical methods may be used to minimize the drilling needed to achieve a desired level of confidence in the calculation of mineable uranium ore grade and tonnage. Because sandstone-type uranium deposits tend to be pod-shaped and are generally aligned along a mineralized trend, this paper proposes a geostatistical method of calculating uranium ore reserves which accounts for this fact and predicts the area within a trend which is underlain by ore. This method uses an indicator value; that is, drill holes which contain mineable ore-grade intercepts are coded as 1, those that do not are coded 0. The indicator may be kriged over the mineralized trend to obtain an estimate of the area underlain by ore. The thickness and grade-thickness may be kriged, and the average ore grade may then be obtained by dividing grade-thickness by thickness, as is conventional for stratabound deposits. The mean grade is then multiplied by the kriged mean thickness to obtain an estimate of the volume, and thence tonnage, of mineable ore within the trend.

Jan 1, 1979

By Biswajit Samanta, Pranjal Pathak

A multimine mineral value chain (MVC) consists of multiple mines in the upstream supplying raw materials to multiple destinations in the downstream. The short-term mine production scheduling problem of a multimine MVC aims to determine the optimal extraction sequence and destination allocation of blocks from all the mines collaboratively to meet the quality and quantity requirements of all the processing plants in each period, subject to all relevant technical and operational constraints of the mining system. It is carried out at shorter scales of days/weeks/months under the purview of long-term production scheduling. An optimal short-term production schedule for MVC involving multiple mines that share the same infrastructure (processing units, stockpiles and waste dumps) requires coordination across the network of mines. Optimizing the short-term production schedules independently at each mine fails to capture the benefit of collaboratively generating schedules for all the mines, resulting in suboptimal schedules. Additionally, in short-term production scheduling, the operations are modeled in greater detail with additional decision variables and constraints to model the more complex multimine MVC situations. This makes the large-scale instances of the problem computationally intractable for standard mixed-integer programming (MIP) solvers. This work presents a customized genetic algorithm (GA)-based heuristic approach to obtain near-optimal solutions to the industrial-scale instances of the short-term production scheduling problem of multimine MVC within a reasonable computation time.

Oct 1, 2022

By MUSTAFA ERKAYAOGLU, ENVER YILMAZ

Coal mining is likely to sustain its critical role as energy requirements are increasing. While surface mining exploits coal seams near the surface, underground mining techniques are crucial for extracting deep coal reserves. Longwall mining is one of the most common methods used in underground coal mining operations. This paper introduces a data-based framework — including data collection, data analysis and the interpretation of operational data — for understanding the system efficiency of a longwall shearer. Operational performance is evaluated by the time between arrivals (TBA) and duration of the shearer stoppages, shearer drums’ reversal time, cutting speed and flit speed on daily production in a longwall top coal caving (LTCC) mine. A discrete event simulation model is developed to represent the bidirectional cutting sequence of a longwall shearer.