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By Michael H. Inglis

The Technology Application Center, in conjunction with the U.S. Bureau of Mines Liaison Program, is studying the use of Landsat data for the monitoring of coal surface mine reclamation activities. Landsat may provide sufficient information to reduce the number of on-site inspections now required. The focus of the project has been the Navajo Coal Mine located in north- western New Mexico and operated by Utah International, Inc. On October 15, 1977, a field team recorded spectral measurements at the mine during the time of Landsat's overpass and a corresponding aerial photographic flight. Training sets were selected from the ground and aircraft data representing vegetated, graded, ungraded and natural environments. A supervised classification of the data was performed by the Stanford University Remote Sensing Laboratory then correlated to aerial photos and mine maps. The results, to date, have been very encouraging.

Jan 1, 1979

By Carla L. Zenti

In recent years, considerable advances have taken place worldwide in the design and construction of first tunnel linings. With these advances, there is a tendency to move away from traditional support that includes heavy open profiles of rolled steel arches, to a lighter solution with the use of an optimized tubular steel cross section rib, and shotcrete reinforced with steel mesh and/or steel fibers, providing a continuous support (Lunardi, 1982). The development of tubular ribs has provided greater design options, increasing flexibility to engineers and contractors while providing a efficient and cost effective construction method. In this article, the authors describe numerical and experimental investigation on this problem, suggesting as a new first lining steel arch design approach by using tubular ribs cross section as new technical solution for first lining underground support.

Jan 1, 2012

By R. E. Driscoll

The exploration, geologist of necessity has to have a wide working knowledge of many specialties other than hiw own, First he has to use his own technical background to find a deposit,, of a mineral that is of interest, Once found, his problems are Just beginning, He then has to assume the role of an economist, an accountant, a mining engineer, a chemist, a metallurgist,, a salesman and what-have you, In the economic field, he must determine the marketability of either the ore or the refined mineral. He must gauge the supply and demand for the particular mineral he is interested in and make his best guess as to ultimate cash flow from a deposit over the estimated life of said deposit, He must then assume the role of a mining man and estimate cost of recovery, including an, evaluation of the most economic mining method, cost of supplies and labor, and again estimate a net cash flow. He must then determine amenability of ore to economic metallurgical methods, he must determine the legal status of the property involved and, after analysis of the specific situation, determine the best approach to a deal, After all of this he must sell it to the people who will put up the money and then put his deal together and sell it to the people who own the minerals, if that be necessary. Then he has to sit back, with crossed fingers and crossed legs wondering for some months, and in many cases even years, whether or not he is right. The expenditures required to open up a mine in this day of wild inflation are such that he has to be right, and the responsibilities are awesome.

Jan 1, 1958

By W. I. Enderlin, P. O. Jackson, J. A. Glissmeyer, K. B. Olsen

A reliable estimate of radon emissions to the environment from underground uranium mines was obtained through measurements of radon in ventilation air at 24 mines and from estimates of radon release from other mine sources. The total production of U308 from the mines sampled represents about 63% of the total U.S. production from underground mines (1978 statistics). Wide variation in the radon emission rate per unit of production was found from mine to mine. Using the total radon emitted and U308 produced by all mines sampled, an average of 26.7 Ci of radon was emitted per ton of U309 produced. The investigation includes a brief study of the sources of variation of the emission rates. A statistically significant relationship was found between the measured radon release rate and the cumulative ore production at several mines.

Jan 1, 1981

By R. D. Miller

Application of shallow seismic reflection to problems associated with mineral exploration, mine planning, abandoned-mine detection, and environmental evaluation has been successful in a variety of geologic settings. Increased dynamic range of recording equipment and decreased cost of processing hardware and software have made shallow seismic reflection a cost-effective means of imaging geologic targets significant to mining operations. Seismic data possess sufficient resolution in many areas to detect faulting with displacement of less than 3 m in coal seams as thin as 2 m at depths of 200 m. Subsurface voids associated with abandoned mines at depths of less than 20 m can be detected and mapped. Seismic reflection has been successful mapping disturbed subsurface associated with dissolution mining of salt Complex geologic features associated with deposition of various hydrothermal minerals have been effectively mapped with high resolution seismic reflection at depths from 80 to over 300 m. Faults in sulfur-bearing cap rock over salt domes have been accurately located, allowing improved efficiency of the dissolution mining process. Shallow high-resolution seismic reflection has the potential to significantly enhance the economics and safety of mine operations.

Jan 1, 1993

By A. D. Rovig

Metallurgical evaluation of autogenous grinding of Anaconda's Berkeley Pit ores indicated that tonnage throughput increases, at a finer flotation feed size, were possible by converting autogenaus mills to steel ball mills. In addition, initial test work showed that the improved grind resulted in slight recovery gains in subsequent flotation processing.

Jan 1, 1974

By A. E. Halim, J. F. Brune

Debate continues over whether barricading in refuge chambers is a good strategy to survive entrapment emergencies in underground coal mines, in particular fires and explosions. Unlike U.S. coal mines, Australian coal mines are not required to use refuge chambers and, instead, have adopted a strategy that focuses on instructing and training miners to self-escape to the surface. This paper analyzes the merits and problems of using refuge chambers or self-escape to the surface to manage emergencies in fires or explosions in an underground coal mine. We found that using refuge chambers may not be the best strategy during extensive fires or when multiple explosions occur. In these situations, mine rescuers are unlikely to be able to extract miners who are sheltered in chambers and, conversely, self-escape may save more lives than sheltering. Chances for successful self-escape are further improved by regular, externally assessed training such as the level 1 emergency exercises required in Queensland, Australia. These exercises put pressure on mine operators to ensure and maintain the effectiveness of their emergency management system.

By B. Tolwinski

Long-Term Open Pit Scheduler or L-TOPS is a new software package for evaluating, planning, and design of open pit mines. L-TOPS transforms geological, economic, and technical information about a mineral deposit into a detailed mining schedule that maximizes economic efficiency without neglecting the practical requirements of mining operations. L-TOPS has been customized for integration with Placer Dome Inc.'s existing in-house resource/reserve optimization software to function as a primary tool for property acquisition studies and for the designing of mines for feasibility studies. This pa-per presents an overview of L-TOPS and reports on its application to Placer Pacific's (Placer Dome's Australian affiliate) Mt. Rawdon project.

Jan 1, 1996

By George D. Haley

This report will be given in two sections. The first sec¬tion outlines techniques and equipment to form almond shaped fluorspar briquettes by means of briquet presses, and the second section outlines techniques of the balling disc. PART I - BRIQUET PRESSES Fluorspar has been briquetted for a number of years and the so called "peach pit" briquet is known to many steelmen. Present production is estimated at over 100,000 tons annually. Slide 1 shows an assortment of various sizes and shapes of briquettes. It is possible to form fluorspar into almost any configuration of briquet. For safety on the melting floor, pillow type briquets are preferred. Ease of mechanical handling and durability of the product are facil¬itated by an almond shape. The dimensions of the almond can vary from 1-in. to 1-1/2-in. in length, from 13/16-in. to 1-in. in width and from 1/2-in. to 1-in. in thickness. The type of equipment to pro¬duce almond shaped fluorspar briquettes is shown in Slide 2. Here we have a Komarek-Greaves and Company 300 ton briquettor equipped with almond rolls. This machine is capable of producing fluorspar briquettes at a rats of 30 tons per hour with power consumption of 35 hp per ton par hour.

Jan 1, 1969

By Anil Kumar

In underground mine production units that employ discrete-vehicle face haulage, feeders are used in the belt network so that vehicles can unload rapidly without transmitting to the conveyor network the high material flow rates that result from rapid unloading. They prevent production bottlenecks at the face, while reducing capacity requirements for downstream materials handling equipment. Similarly, surge bins may be installed at intermediate locations in the network to smooth flows from a number of upstream sources, thereby reducing downstream belt capacity requirements. This paper introduces new stochastic process models to temporally describe loading patterns from unit operations and techniques for computing the probability of various fill levels for the feeder or surge bin. These results may be used to analyze the effect of alternative bin or feeder capacities and discharge rates on the performance and costs of the materials handling system.

Jan 1, 1994

By E. Lee

The behavior of As bioleaching using Acidithiobacillus thiooxidans (A. thiooxidans) in mine tailings containing highly concentrated As contents (i.e., As=33877 mg/kg) was systematically evaluated according to the changes in temperature (25?40°C, pulp density=0.5%, pH=1.8), pulp density (0.5?4%, temp=30°C, pH=1.8), and initial pH(1.8?2.2, temp=30°C, pulp density=0.5%). The changes in temperature and pulp density affected the As leaching behavior more than the change in initial pH did. Based on the pH and oxidation-reduction potential (ORP) results, the As leaching was attributed to solution acidification. In particular, As leaching was accelerated with increasing sulfate production in the reacting solution. After bioleaching, surface of tailings examined that many pores which dissolved As were formed by a chemical reaction due to bacteria. The As bioleaching efficiency by A. thiooxidans was enhanced by the oxidation of both the added elemental sulfur and the sulfur compounds in the mine tailings. The As bioleaching efficiency was maximized at 50.5% under conditions of an initial pH of 2.2, reaction temperature of 30°C, and pulp density of 0.5%.

Feb 23, 2014

By S. G. Dixit

Alunite (KAl3(SO4)2(OH)6] is one of the important nonbauxitic resources for aluminum in U.S.A. The major gangue material associated with a unite ore body is quartz. Experimental results indicate that oleic acid flotation of alunite is quite effective in upgrading the ore. The flotation chemistry of the alunite/oleate system has been investigated using various techniques such as: hallimond tube flotation response, measurement of adsorption density using I4C labeled oleated, electrokinetic measurements, infrared spectral studies, contact angle measurements and thermochemical measurements using an isothermal microcalorimeter. Alunite has been found to float readily with oleate in the pH range 4-10.5 and its flotation response is enhanced at higher temperatures. The PZC of alunite has been determined to be at pH 7.2 ± 0.15 which agrees with what would be predicted from solution chemistry and from the flotation response with physically adsorbed collectors. Infrared spectra show a specific peak in the range 1585-1600 cm-1 which has been attributed to the formation of an aluminum oleate surface species. Both adsorption density measurements and infrared spectra indicate that during adsorption multilayers are formed. The heat of adsorption of oleate on alunite has been found to be endothermic and of the order of 4-6 KJ/ mole.

Jan 1, 1980

By K. J. Sollman

As a class, silicate minerals have likely found the broadest, if not largest volume, use in combination with polymeric binders of all industrial minerals. Among the silicates, calcium metasilicate, wollastonite, enjoys a front runner position in a near universal sense. It is a viable and desirable part of composites ranging from thin films to large moldings; from a common filler/extender for paint for your garage to a reinforcement for the exterior surfaces of a luxury vehicle affordable to very few. This article is focused upon the variations in particle morphology and the surface characteristics which, by way of commercial examples and discussion of active research programs, make this environmentally benign mineral so unique.

Jan 1, 1993

By J. W. Mustard

The Macmillan Pass tungsten property (MacTung) is the largest known copper-tungsten, calcic, exoskarn deposit in the Western Hemisphere. Located on the border between the Yukon and Northwest Territories in northwestern Canada, the deposit crops out on Mt. Allen within the Selwyn Mountain Range. It was discovered in 1962 by a subsidiary of AMAX Inc. and has since been explored by 16,300 meters of surface and underground diamond drilling and by 800 meters of underground development. Geologic reserves are in excess of 30 million tons, grading slightly less than 1.0% WO3. Scheelite (CaWO3 ) is the main mineral of economic interest. Accessible by road, the property is not in production. Previously estimated reserves at MacTung have been unable to fully utilize all the geological controls on mineralization. In the past three years, however, an intensive program has been underway to improve our understanding of the deposit and to use the resulting information in a more precise way. This paper will discuss the key aspects of the geology as they specifically relate to reserve estimation and will demonstrate how these controls are being used in a geostatistical model of the deposit.

Jan 1, 1985

By A. B. Cecala, G. W. Klinowski

Introduction The US Bureau of Mines has designed and evaluated total mill ventilation systems (TMVS) at two mineral-processing operations. Both systems have proven proficient at cost-effectively reducing respirable dust levels throughout the mills. An 11.8-m3/sec (25,000-cfm) system installed at a clay-processing mill provided about 10 air changes per hour (acph). This system reduced respirable dust concentrations by about 40% throughout the mill building. The second evaluation was performed at a silica sand operation. Tests were performed with 23.6 and 47.2 m3/sec (50,000 and 100,000 cfm) of ventilation to the mill building, corresponding to 17 and 34 acph. Average millwide respirable dust reductions were 36% and 64%, respectively. This work was done to determine general guidelines and design criteria for operations that may be interested in implementing TMVS. TMVS should be designed to draw clean make-up air in near the base of the mill. This air provides general purging and may clear some dust-laden areas throughout the mill structure. It is discharged at or near the top of the structure. Without the TMVS, dust can exit the building through open doors, windows, etc. and contaminate outside plant workers. This dust can also be recirculated back into the mill building causing additional contamination problems. TMVS is not a stand-alone system. It is a supplemental technique to assist other localized dust control systems (Mody et al., 1987). Testing Total mill ventilation systems were evaluated at two processing operations. For both tests, the primary goal was to determine the reduction in respirable dust throughout the structure. Test site No. 1. The first evaluation was performed at a clay-crushing and screening mill in New York. The mill's base dimensions were 39.6 x 9.8 m (130 x 32 ft), giving a volumetric capacity of 4250 m3 (150,000 cu ft). The TMVS was designed to provide 12 m3/sec (25,430 cfm) of ventilation air to the mill, representing about 10 acph. This was accomplished by three 4 m3/sec (8475 cfm) roof-powered exhaustors that were evenly spaced across the roof. Three wall louvers provided inlets for make-up air at the mill's base. Two evaluations were performed at this mill. The first occurred for two days in December when outside air temperatures ranged from -12.2° to 4.4° C (10° to 40° F). Temperatures with the wind chill factor dropped as low as -34° to -40° C (-29 to -40° F) during the early morning. The second evaluation was in April when outside air temperatures ranged between 10° to 26.7° C (50° to 80° F). These two evaluations verified the effectiveness of TMVS in lowering respirable-dust concentrations throughout the mill. Gravimetric-sampler respirable-dust concentrations in December ranged from 0.22 to 2.39 mg/m3 under normal conditions, compared to 0.13 to 1.55 mg/m3 with TMVS. In April, respirable dust concentrations ranged from 0.29 to 4.84 mg/m3 under normal conditions compared to 0.21 to 2.37 mg/m3 with the system on. TMVS also increased visibility throughout the mill building. Dust reductions for gravimetric and RAM-I instruments are listed in Table 1. Each value was determined by comparing the average concentration for the entire day of testing for normal and TMVS values. The mean/standard deviation values for gravimetric and RAM-1 results were 42.5/17.6 and 37.1/16.8, respectively.

Jan 1, 1996

By Marc. A. Meyers

The analysis of the phenomena involved in the determination of the compressive strength of iron-ore agglomerates leads to the identification of the important parameters. It is shown mathematically that the pellet rupture strength is proportional to the cross-sectional area. Fracture is initiated at the center of the pellets by the tensile stresses developed by the compressive loads normally to the compression axis. The variation in strength between individual pellets of identical composition and subjected to identical treatments is due to internal voids of varying sizes, that act as stress-concentration sites. Two novel testing procedures are proposed. The first consists of testing the pellets between two plates having three steel spheres each. This configuration simulates much better the environment actually encountered by the pellets. The second procedure consists of a thick-walled cylinder in which a piston penetrates; a large group of pellets is tested simultaneously, as the stress versus strain plot is being recorded. This latter test presents significant advantages over the conventional testing procedure; the main one is that one single test is sufficient to characterize the mechanical response of the pellets.

Jan 1, 1981

By George Fumich

The Office of Coal Research has been supporting the development of processes for producing synthetic pipeline gas from coal since 1964. .Some of this work has also been jointly supported by the American Gas Association. The work has progressed through laboratory investigation, to bench scale, to pilot plant. It was far from a crash program, generally being fund-limited.. As of one year ago, we had reached the following position: 1. The Institute of Gas Technology HYGAS. process pilot plant in Chicago, Illinois, was in the process of being finally completed. This plant is designed to produce about 1,500,000 cubic feet of pipeline-quality gas per day from 75 tons of coal. 2. The Consolidation Coal Company, CO2 Acceptor Process pilot plant in Rapid City, South Dakota, was well._ on its way to completion. This plant, designed primarily for lignite and subbituminous coals, has about one-half the design capacity of the HYGAS plant. Additionally, the initial construction did not provide for cleanup and methanation; only the preliminary synthesis gas is produced. 3. The Bituminous Coal Research, Inca, BI-GAS pilot plant was in a preliminary design stage. A site had been selected near Homer City, Pennsylvania, to build this plant, planned to consume 120 tons of coal per day. Meanwhile, as you are all well aware, a natural gas shortage was developing in this country. Much has been published about it, so I will not. bother you with further details. Suffice it to say that the reserve-to-production ratio has been steadily declining, because we have been using.-as-faster than we have been find-

Jan 1, 1972

Longwall mining is a commonly used method of coal extraction that involves the complete removal of large, rectangular panels of coal. Longwall mining causes the immediate seam roof to break and fall into the void created by mining. The convergence of the surrounding strata towards the mining void causes subsidence on the surface. The subsidence magnitude is related not only to the mining depth, the topography, the geological features and the overburden materials, but also to the sequence of the strata overlying a coal seam. In additional to the vertical subsidence which is evident at the surface, there are also horizontal movements inwards toward the centre of the void, which cause the surface to tilt, bend, stretch and com-press. This paper presents a parametric investigation of the influence of the overburden stratigraphy to surface deformations due to longwall mining using 2D finite element models. Models simulate rock movement by applying equivalent edge load to the open roof.

Jan 1, 2008

By R. E. Scheffel

In February, 1976, Ranchers Exploration and Development Corporation obtained an option from Foote Minerals, Inc., to evaluate reprocessing of two uranium tailing piles. Foote received ownership of the Naturita and Durango tailing piles in 1967 through the purchase of Vanadium Corporation of America. The option was exercised in November, 1976, after initial testwork proved that a viable extraction technique existed. Preparation for production at Naturita began immediately with engineering and en¬vironmental permitting proceeding simultaneously. Production began in December, 1977, just 22 months after acquisition of the property and-was completed 17 months later.

Jan 1, 1981

By E. H. Cho, P. K. Dai

An acid mine drainage sludge sample, containing 3.6% Mn, 0.18% Ni, 0.15% Co and 0.39% Zn, was obtained from central West Virginia. The sample was leached at room temperature with a pH 3 sulfuric acid solution. Air was then bubbled through the leach solution at pH 4.5 to precipitate the iron. The leach solution contained 258 ppm Zn, 105 ppm Ni, 90 ppm Co and 2050 ppm Mn. Three solvent extraction studies were performed to selectively extract these metal ions in a sequential operation with DEHPA. Cyanex 272 and Lix 84. The A/O ratio was one, and the extractants were diluted ten times with kerosene. A study of solvent extraction with DEHPA showed that Zn could be extracted without Ni or Co up to a pH of 2.75. A pH of 2.75 is considered to be the optimum pH to maximize the selective separation of Zn from Mn. The separation factor of Co over manganese suggests that the two metal ions should be extracted together by Cyanex 272. The separation factor of Co over Ni indicates that these two metal ions can be separated most effectively around pH 5.3. Also, Ni can be effectively extracted by Lix 84 above pH 5.5.

Jan 1, 1995