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By Richard Hogg, Erol Kaya, Jan M. Mutmansky

Characterization of the size, shape, chemical composition, and mineralogical content of mine airborne dusts generally requires a larger mass of dust particles than is typically collected using traditional sampling devices. In this paper, the general design of a passive dust collector is described and the field results are presented. The collector was constructed of galvanized sheet metal duct with a resin-coated honeycomb to provide an elutriation-type system for particle collection. Several versions of the collector were used in the field portions of the research. The dust samples collected from underground coal mines were found to possess angular particle shapes, relatively consistent size distributions, and elemental compositions that showed relatively little variation, at least for the more prevalent elements. In addition, the distributions of particles sizes obtained from the passive dust collector appear to be similar to those of samples collected at the same time in a conventional personal sampler except that the passive device seems to collect a larger quantity of coarse, non- respirable particles. Conclusions on the suitability of this dust collector for collecting characterization samples are presented. In addition, the potential for using such a dust collection system for supplying dusts for biomedical research is discussed.

Jan 1, 1993

By V. B. Achanti, A. W. Khair

Developing a laboratory procedure for the determination of coal-seam compressive strength has been a subject of discussion for many decades, and the reliability of laboratory determinations is often the subject of debate. A coal seam’s characteristics, the method of sample collection, the specimen preparation method and the testing procedure can often result in drastic variations in the test results. In this paper, the development of a laboratory testing procedure for the determination of coal-seam compressive strength is presented. Two samples that were collected from different coal seams were tested in this study. First, the inherent characteristics, i.e., coal structure. Hardgrove grindability index (HGI), Slake durability index, proximate analysis and mechanical properties (Young's modules and Poisson's ratio), of each coal were determined. The results were used to categorize the coal scams in terms of the characteristics liable to produce variable strength data in typical laboratory tests. Second, two commonly used laboratory specimen shapes, cylindrical and cubical, were tested to determine which shape produced the most reproducible strength values. Third, four loading rates within the static testing range, i.e., 0.007, 0.07, 0.34 and 0.7 MPa/s (1.0, 10, 50 and 100 psi/sec), were used to determine the ideal loading rate. Finally, the number of test samples required to produce strength data within the acceptable standard deviation, considering coal seam characteristics, were established. Background Laboratory testing of coal specimens for the determination of seam compressive strength has been a subject of discussion since the early 1900s. Many researchers have tested coal specimens to estimate coal-seam compressive strength for use in pillar design to insure the safe operation of [ ] mines (Unrug et al., 1986; and Hirt et al.. 1992). Yet, there is a lack of a universal procedure, and, no matter which approach is used, it becomes the subject of intensive debate. A great deal of work has been performed on the subject, and there is much information available in the literature. Some of this work concerns quantifying the influence of specimen shape and size on compressive strength (Bieniawski. 1968: Barron et al.. 1992: Khair and Xu 1994; and Khair 1994). As indicted in the literature, coal is a heterogeneous material, consisting of discontinuities such as cleats and bedding planes, which are likely to produce variable strength results (Holland, 1964; Unrug et al., 1986). Some of the prominent issues that influence the determination of coal-seam compressive strength in the laboratory are: •the collection of a representative sample from a coal seam; •the geometry, i.e., shape and size of the specimens to be prepared and tested: •the loading rate at which the specimens are to be tested:

Jan 1, 1997

By M. Schultz

The cost of remediation often drives the selection of the preferred remedial alternative at hazardous waste sites. The use of probabilistic cost/risk analyses can aid in predicting costs of remedial alternatives. Three types of information are discussed in performing cost/risk analyses: (1) data on the quantity of contamination versus the contaminant concentration; (2) unit costs of remediation for the remedial alternatives; and (3) risk to contaminant concentration relationships. Cost/risk evaluations are performed on a site-by-site basis, to account for combined risks of different contaminants and differences in quantity to be remediated versus contaminant concentration. The cost/risk analysis produces a graph of risk versus cost for each of the remedial alternatives. These costs are then compared to facilitate selection of a preferred alternative. An example of comparison of alternatives is illustrated for a historic coal gasification site.

Jan 1, 1992

By I. Y. Bausov, L. G. Stolarczyk, R. E. Pillmore, A. J. Hillard, J. T. Duncan

"Prevalence of lung disease in younger miners surprised industry regulators, congressional members, researchers and black lung clinic staff members. Mitigation researcher focused on low-coal mining in the Appalachian regions until Miners Colfax Medical Center (MCMC) Black Lung Clinic examinations discovered 25 of 72 Wyoming coal miners with lung disease. To reverse recent upward trend in lung disease, research programatic have been directed at reducing exposure to respirable “float” dust. This paper suggests broadening the scope of research to include boundary detection in efforts to improve outcomes. Beginning with a better understanding of biochemistry of anaerobic bacteria methylation processes precipitating sulfur and heavy metals into thin seam boundary layers. Expanding research and development objective to focused on minimization of bit-pick crushing cone volume and preventing mining thin boundary coal layers and out-of-seam dilution. Black lung clinical evaluations of miner will confirm outcomes directed towards reduced occupational disease and smoke stack emissions. INTRODUCTION Miner exposer to bit-tip crushing cone volume, fragmentation and auger movement generated respirable “float” dust and boiler emissions are related science-technology –engineering-mathematics (STEM) problems. Formidable but not intractable problems are driven by oxidation of upper flood plain elements in the periodic table and biochemical metabolic presses occurring in coal basin. Because of burial compaction, quartz and trace heavy metals (Fe2+, Mg2+) are concentrated in thin seam boundary layers. By not cutting through thin boundary coal layer and out-of-seam into hard quartz containing rock layers, miner lung disease and smoke stack emissions are minimized. Cutting bit-pick elastic wave hydrodynamic principle force vectors in the coal layer must be aligned to minimize respirable dust generation, constrained by fragmentation size. Dust abatement by water spray and machine design are effective; but for, failure to address cutting cone dust volume generation and its distribution along run-of-mine (ROM) transportation systems the boiler. Real-time precision thickness measurements by integrated cutting drum (icDrum) sensor, machine man-interdiction from a dust free control room, is a cost effective way to prevents respirable dust exposure. The recommended STEM research and demonstration initiative addresses issues raised by discoveries of increased rate of lung disease discovered in young miners and concerns over emissions from coal-fired electric generation stations (Global Warming). In-mine demonstrations must be validated by on-site MCMC mobile Black Lung Clinic data acquisition and analysis."

Jan 1, 2016

By R. R. Odman

The Malmberget Division of LKAB is located 70 km north of the arctic circle and has about 2000 employees. The dominating products are sinter feed concentrate and pellets. A general flow sheet for the operation is shown in Figure 1. About 20 percent of the ore body consists of hematite, which is mined separately and processed into sinter feed concentrate. That pert of the ore consisting of magnetite passes through a dry cobbing plant. The robbing process includes crushing, screening and dry magnetic separation. The entire cobbing product is used as feed for the wet concentrator. After rod mill grinding and magnetic separation the concentrated slurry is classified. The coarse fraction (+200 mesh) becomes sinter feed concentrate and the slime fraction after further ball mill grinding and magnetic separation, becomes pelletizing feed. A small quantity of the magnetite ore is processed into special iron-rich products in the the wet concentrator. Two types of pelletizing plant are used, shaft furnace and straight grate. This paper will deal only with experience gained at the straight grate plant.

Jan 1, 1979

By R. RAMSDEN

The deep South African gold mines rely on refrigeration to provide a safe working environment. Chilled water, which is produced in large central refrigeration plants, is distributed throughout mines In insulated pipes. In view of the high cost of the insulation materials and recent regulations which prohibit the use of certain insulation materials, a careful examination of the actual benefits of insulating chilled water pipes was undertaken. The objective of the investigation was to produce general guidelines regarding the use of insulation, but the results of numerous studies have shown that the use of insulation is extremely site specific and thus no general guidelines can be given. To assist ventilation engineers with studies on insulation requirements for their cooling systems a computer program has been developed. This paper describes the personal computer program which contains the same user friendly interface as developed for other COMRO programs. Is fully menu driven and incorporates a comprehensive HELP facility which provides background information and assistance with the selection of input data. The effects on the ventilation air and chilled water temperatures from not insulating chilled water pipes in certain areas are calculated. Air leakage, heat flow from the surrounding rock to the ventilation air and heat flow from the ventilation air to the water flowing in chilled water pipes are taken into account. A simple cooling system is considered in which cold water is distributed over a distance of 1 000 m through pipes to a single air cooler. The influences of changes in the temperature of the chilled water and ventilation air, as well as air leakage on the insulation requirements are determined.

Jan 1, 1991

By R. Hiebert, M. Canty, S. Beckman

An innovative biological process is described for the treatment of cyanide-, metals- and nitrate-contaminated mine process water. The technology was tested for its ability to detoxify cyanide and nitrate and to immobilize metals in wastewater from agitation cyanide leaching. A pilot-scale demonstration is described in which a pilot plant was constructed to demonstrate the technology on a mine process-waste stream at a mine in Nevada. The demonstration was performed jointly under the Mine Waste Technology Program (MWTP), funded by the US Environmental Protection Agency (EPA) and jointly administered by the US De¬partment of Energy's (DOE) Western Environmental Technology Office (WETO) under Interagency Agree¬ment Number DW89938513-01-0. The Superfund Innovative Technology Evaluation (SITE) demonstration program was also involved in the project. MSE Technology Applications Inc. (MSE), Butte, MT, was the contractor responsible for conducting the project, and Pintail Systems Inc., Aurora, CO, was the technology provider. The pilot-scale unit was field-tested at Echo Bay's McCoy/Cove Mine southwest of Battle Mountain, NV. The biotreatment process was considered successful in destroying cyanide in the mine process water. The process was also determined to be effective in removing metals. The pH was consistently neutralized and nitrates were successfully removed from the mine process water. From the results of these pilot-scale tests, it was concluded that the biotreatment process potentially of¬fers an innovative, cost-effective alternative for the treatment of mining wastewaters.

Jan 1, 2000

By J. M. Johnson, J. Vialpando, C. Lee

Since 1951, Molycorp has operated the Mountain Pass Mine in San Bernardino County, California to extract fourteen lanthanide elements, or rare earths, from a carbonate ore body. Wastes generated by the open pit mining operation consist of overburden and 1800 tpd of tailings. The tailings are classified as Group B mining wastes by California regulators. Paste tailings is one of several alternatives being considered during the permitting process for future mine operations. This paper presents the findings of study to assess the feasibility of using paste tailings to develop an unsaturated tailings stack instead of dilute slurry discharge behind a tailings dam.

Jan 1, 2004

By B. Culkin

The production of fine particle products within the mineral processing industry is a very important market segment. Many of these products are processed in an aqueous state and must ultimately be dewatered. This entails processes which are very energy and capital intensive. The introduction of membrane based dewatering systems has offered great promise in the area of energy saving and operating costs. Unfortunately, membrane separators have not yet had the ability to handle high solids. New Logic introduces a system which can concentrate a low solids stream to a high solids sludge in a one pass, very energy efficient system.

Jan 1, 1993

By A. K. Sinha

Research shows that continuous mining sections can normally produce around 950 tons per shift in a seam 5 or 6 ft. thick. The shuttle cars as well as the continuous haulage systems are able to match with the continuous miners in capacity. However, in practice both of the two systems seem to be averaging at around 450 to 500 tons per shift in production. Continuous haulage systems are preferred in thin seams particularly where the floor is soft.

Jan 1, 1981

By Kanaya Koichiro

Doyashiki Concentrator in Hanaoka mine of Dowa Mining Co., Ltd. started the operation in 1943, treating the ore mainly from Doyashiki ore deposits. After the cessation of mining of Doyashiki ore body in 1973, Doyashiki concentrator began to treat the ore from Fukazawa mine instead in the same year, and furthermore the ore from Ezuri mine In 1979. Currently Doyashiki concentrator treats 30,000 tons of ore per month from both mines. The ore treated is complex sulfide ore, called "Kuroko" (black ore), and the principal minerals contained in the ore are chalcopyrite, galena, sphalerite, pyrite, and barite, accompanied by bornite, tetrahedrite, tennantite, covellite, stromeyerite, argentite, polybasite, pearcite, and electrum. The Principal gangue minerals are quartz, gypsum and clay. The grade of the feed to the concentrator averages 0.9 p/t Au, 110 g/t Ag, 1.1 %Cu, 2.8 %Pb, 9.2 %Zn, 5.0 % Pyrite-S and 13% BaS04. The feed is, after washing and two-stage crushing, ground to 88% minus 200 mesh in a rod mill and ball mills with cyclone classifiers, and five concentrates are recovered by flotation. Primarily copper-lead bulk concentrate is recovered by sulfurous acid-lime flotation method, and then from the bulk concentrate copper concentrate is floated by hot pulp flotation method, sinks being lead concentrate. Zinc concentrate is recovered from the tailing of copper-lead bulk flotation, pyrite concentrate from zinc flotation tailing and barite concentrate from pyrite flotation tailing. The final tailing is sent to the dam.

Jan 1, 1982

By E. V. Bowman

This paper is intended to deal with the material handling aspects of fine coal cleaning as applied to a recently built plaint in: southern West Virginia. This plant is processing 160 tons per hour of 1/4" x.0 coal on a two shift basis. Past experience with this very friable low volatile metallurgical coal indicated that its plastometer readings, varied directly with the size and length of time elapsing between mining' and ultimate consumption. Due to the mines location with, respect to its consumers, little could be done to decrease the time element. Studies indicated that the plastometer readings are considerably less in the minus 60 mesh range than that experienced in the plus 60 mesh sizes. Therefore, handling the coal in such a manner as to have the least amount of degradation became extremely important.

Jan 1, 1961

By C. H. Bucknam

An interlaboratory testing program was undertaken in support of an ASTM standardization program for simultaneous combustion-infrared analysis for carbon and sulfur in ores and related materials. Statistical analysis results from the study are used to generate the within-laboratory and between-laboratory precision data needed for standardization of the methods. The interlaboratory precision statistics are also interpreted to estimate the uncertainty in calculation of net carbonate value classifications using a simplified quantitative risk analysis technique.

Jan 1, 1998

By M. A. Sochocky

Rod mills were developed, as a logical substitute for the rolls crusher when larger tonnages had to be handled, on a continuous basis. Today, with even larger tonnages to process, the trend is to install larger equipment, automate the plant and develop the highest availability possible, in order to cut costs. The rod mills, because of design limitations in size and speed 1'2, are not able to meet these new requirements. The autogenous mill was a timely development and serves as an excellent alternative for ores that are suitable to this type of grinding. When ores are not amenable to autogenous grinding, selection of a flowsheet is dictated by liberation characteristics and unit operations to be used for mineral recovery.. The following alternatives are available: (a) Multiple rod mills, capable of drawing no more than 2000 HP each, followed by ball mills. (b) Gyradisc crusher followed by two stages of ball mill grinding.3 (c) Tertiary crushing followed by closed circuit single stage ball mills grinding to approximately -100 mesh, as in the copper industry. (d) Tertiary' crushing followed by two-stage, ball milling. Each stage will operate in closed circuit with either screens or cyclones. It is this last alternative, particularly as it

Jan 1, 1972

By Jianliang Li, Jan M. Mutmansky

This study analyzed laboratory comminution techniques for respirable mine dust generation and the properties of the resulting dusts. It was the objective of the study to determine the suitability of the resulting dusts in reflecting the properties of natural airborne dust. This paper deals specifically with the amount of contamination introduced into the generated dust as a result of abrasion when using nine different grinding methods. The analysis was made by comparing the content of 25 chemical elements in the lab-generated dusts with the same elements in the airborne coal mine dusts. It was found that all the lab-generated dusts possessed contamination but that several methods produced smaller percentages of contamination and that the residence time in the grinding device was an important factor in the contamination levels.

Jan 1, 1992

By M. Misra

A sample of thorium-contaminated soil from Kirtland Air Force Base (AFB) was subjected to froth flotation for removing thorium contaminants. A series of flotation tests were conducted to screen and evaluate the reagents. Among the collectors used, sodium oleate exhibited to show the promising results. Preliminary tests showed that a concentrate having activity as high as 5300 pCi/g can be obtained from the contaminated feed soil having activity 800 pCi/g. The volume reduction obtained was 89% and the activity recovery in the concentrate was 68%. The paper discusses the physico-chemical characterization data and the potential physical separation decontamination schemes for the thorium contaminated soils.

Jan 1, 1996

By S. D. Hill

State-of-the art precious metal recovery practice uses cyanide leach solutions to extract the valuable constituents from ores, wastes, and tailings. Activated carbon is then used as an adsorbent in either a carbon-in-pulp system or counter-current flow columns to concentrate and recover the precious metals. Existing techniques for recovering precious metals from carbon prior to the precipitation or electrowinning of the metal involve either the use of dilute aqueous hydroxide solutions at elevated temperature and pressure or, as in a more recent method, the use of a strong cyanide soak followed by a water strip solution at an elevated temperature. Despite past Bureau efforts in the area of precious metal recovery, the ex- traction of gold from pregnant leach solutions remains the most serious drawback in carbon-in- pulp and heap leach processing of low-grade ores containing precious metal values. A second disadvantage in the current practice is the interference in adsorption and desorption that occurs due to the presence of other heavy metal cations in cyanide leach solutions. Specific objectives of current Salt Lake City Research Center precious metals research are to develop less energy intensive and more economic methods for recovering gold, silver, and by- product metals from low-grade resources. To meet these objectives, we are investigating noncyanide leaching reagents, ion exchange resins, solvent extractants, and novel electrowinnlng procedures.

Jan 1, 1984

By Harry J. Fitzgerald

During World War II mining machinery manufacturers were limited in the development of their product improvement programs. Following the war, however, the ideas and intentions of both the users and manufacturers of mining equipment became evident. The Coal Industry launched a series of events which indicated their determination to rise to the economic challenge of developing profitable machines which would eliminate the out-dated and back-breaking methods of mining previously used. Two major technological advances were developed as a result of the ambitious goals forecast by the Coal Industry: 1. Coal mining was going "off-track" and concentrated mining operations were to follow in rapid succession. 2. Carbide tools provided the remaining missing contribution to another technological breakthrough....Continuous Mining. Little did the inventors realize the significance of the misnomer they created because twenty-five years later the industry is still striving to secure the results implied by the meaning of the word...."Continuous". Nevertheless, all major manufacturers embarked on programs in an attempt to compete for recognition in this new mechanized-mining endeavor Eventually in 1950 there were three types of boring machines and two types of ripping machines being manufactured. Mining Speed was the desired goal.

Jan 1, 1970

By S. J. Porter, M. T. McRae

The Melbourne City Link project includes two three-lane highway tunnels, 1.6 and 3.4km long, respectively, which are both approximately 16 meters wide and 9 meters high. The tunnels will be excavated through interbedded, moderately to highly jointed siltstones and sandstones of the Silurian Age Melbourne Mudstone formation over the major parts of their lengths. The strength of the intact rock varies from less than 5 MPa to greater than 70 MPa. Based on the available information regarding the performance of large span tunnels in weak rock, it was considered that the commonly applied empirical design guidelines for tunnel support, based on rock mass classification systems, should be augmented by more explicit design methods. The support design was, therefore, validated by analytical procedures, including numerical analyses, which are described in this paper.

Jan 1, 1997

By H. B. Trinh, R. R. Srivastava

"Spent auto-catalyst is a potential secondary resource because of the higher concentration of valuable platinum group metals (PGMs) as compared to the primary ores. Despite the well-developed commercially tenable technologies, further researches are being carried out to extract the PGMs with high efficiency. It is however, critical in this context to reuse not only the PGMs but also other metals contained in the spent auto-catalyst particularly that of the cordierite substrate such as aluminum, magnesium and cerium oxide (CeO2). This is important in view of the fact that no recycling process has ever stressed upon the recovery of cordierite substrate and CeO2 since the main target metals are mostly the PGMs. In this study, a new hydrometallurgical approach has been proposed in order to recover the PGMs as well as cerium oxide and materials from the cordierite substrate by using sodium hydroxide roasting followed by sulfuric acid dissolution. Under the optimal conditions for roasting at above 600°C, and weight ratio of sample to NaOH of 1:1 for 60 min, the cordierite was converted to the soluble phases. Dissolution of the roasting products using H2SO4 solution (1M) at 25°C for 60 min enriched the PGMs and Cerium oxide contents in the residue. Subsequently, PGMs in solution after dissolution can be cemented using Al and Cerium oxide in residue can be recovered by hot digestion using concentrated H2SO4.. INTRODUCTION Auto-catalyst can significantly control the gaseous emission of automobiles, and has been considered as a potential secondary source of Platinum group metals (PGMs) after being decommissioned from the vehicles. The PGMs demand is continuously increasing to comply with the growing vehicle population and the tightening of emission standards all over the world; meanwhile the natural resources of these metals is facing the threat of depletion. Therefore, it is crucial to progressively substitute with an alternate resource to supply PGMs other than that of the primary ores. Nowadays, vehicular transportations worldwide are totally installed with the auto-catalysts. However, they should be replaced after reaching their service life. If there is no recycling of such resources, huge amount of valuable metals will be wasted. The quantity of PGMs that can be recovered from the spent auto-catalyst depends on the size of car, which averages to 1-2 grams for small cars and 12-15 grams for the big truck; this is significantly higher than that of the primary ores containing 2-10 grams PGMs per ton. Consequently, the recovery of PGMs from spent auto-catalyst becomes extremely favorable as compared to the primary resources due to higher concentration of PGMs, with much lower and simpler processing steps, and lesser pollution."

Jan 1, 2018