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By V. K. Gupta

The experimental results of some wet batch and continuous grinding experiments carried out in a 40 x 40 cm grate discharge ball mill have been analyzed for the variation of the grinding rate parameters, Si, with various operating conditions using a linearized population balance model. The wet grinding tests were carried out under conditions which were very similar to those encountered in the actual practice in plant operation. Well distributed -4 and -20 mesh feeds of two complex pyritic ores were used. The volume-percent solids in the pulp ranged from 30-40, the particle load from 5-8 kg, and the solids feed rate from 70-1 10 kg/hr.

Jan 1, 1981

By R Small, S Combrinck, R Lindsay

Maintaining your competitive edge in the growing Australian mining sector today is an arduous task. With an ever increasing demand to extract more ore, safely, complete visibility throughout the blasting cycle has become vital to any operation. To achieve this requires full two way communication with every detonator during the testing and programming cycle, as well as, inside the firing window. Concerned with an increase in the number of incidents involving mining equipment, uncovering and digging into unknown misfires on-sites across Australia, Black Star Mine made the decision to embark on the use of electronic detonators to eliminate this hazard. With this safety goal achieved, the mine set about using the added benefits of electronic detonators to improve their drill and blast processes with impressive results.CITATION:Combrinck, S, Lindsay, R and Small, R, 2012. Eliminating unidentified misfires at Xstrata ZincÆs open pits through the application of electronic detonators, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 27-30 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

By Lloyd R. Michels, Burke Cartwright, S. F. Ravitz

"INTRODUCTION Frequent attempts have be,made in the electrolysis of molten magnesium chloride to regenerate the electrolyte by allowing the chlorice generated at the anwdo to read with magnesium oxide and carbon within the melt according to the following reactions: (1) MgO + C + CL2 = MgCl2 + CO,(2) 2MgO + C + 2C12 = 2MgC12. + CO2.The principal advantages of such a procedure are that (1) the direct source of magnesium is magnesium oxide rather than the more expensive dehydrated magnesium chloride and (2) it is not necessary to handle or dispose of large quantities of chlorine or hydogen chloride.Grätzll 5/ proposed the use of an MgO carbon feed in a more or,less compact form in the anode compartment, of the cell. In a patent issued to Magall Aktiengecellschaft, 6/ a compact mixture of MgO and carbon is used as the anode itself. Kato 7/ and Backer 8/ add the feed in finely divided form to the surface of the anode compartment. The Bureau of Mines 2/ recently made a pilot-plant investigation of the electrolysis of suspension of MgO and carbon from chloride melts, in which it was found that although,current efficiencies of 60 to 70 percent were obtainable, the formation of sludges containing MgO, carbon, and magnesium seriously interfered with the operation of the cell,"

Apr 1, 1945

By Thomas J. Peters

The Snowbank study area, which had been proposed as Wilderness, lies about 5 air mi southwest of Cascade, Idaho, and about 60 air mi north of Boise. The eastern boundary of the north-south-elongate study area lies 1-to 2-mi east of Cascade Reservoir; the western boundary is contiguous, in part, with the western boundary of Valley county. The 8,200-acre study area is underlain by Cretaceous granitoid rocks of the Idaho batholith. Three prospects were found in or near the study area during a library and field search. Gold occurs at one 30-ft adit, but the gold-bearing structure appeared too narrow to contain resources. Two other prospects appeared essentially unmineralized. No evidence of geothermal activity was observed. Rock in the area is not potentially useful as dimension stone because it does not split into flat slabs. To be used as aggregate, the rock would require crushing and hauling to distant markets. One of 18 alluvium concentrate (placer) samples contained free gold, worth $1.07 per cubic yard of gravel (at a $350 per oz gold price). No alluvial bars were seen; deposits were too small to contain gold resources or be considered gravel resources.

Jan 1, 1993

By G. L. Oldright

The studies previously made on Smelting in the Lead Blast Furnace have dealt with the custom smelter of the International Smelting Co. at Tooele, Utah, and on the smelter of the Bunker Hill & Sullivan Mining & Smelting Co. at Kellogg, Idaho. The International plant may be considered representative of the traditional custom smelter. The lead smelter of the future seemingly will have to treat increasingly richer lead charges. This feature was then stressed in describing the Bunker Hill plant.

Jan 1, 1934

By Terry J. Kreidler

In recent years, west-central Arizona and adjacent California have become the focus of geologic and exploration attention because of its excellent exposure of detachment-fault terrane. Detachment faults, normal faults with nearly horizontal fault planes, are the result of regional extension. Rocks on the lower plate consist of mylonitized intrusive, metasedimentary and crystalline rocks highly altered to chlorite; upper plate rocks comprise sedimentary, volcanic, metasedimentary, and metavolcanic rocks. The movement of the detachment fault causes the rocks on the upper plate to be severely fractured and brecciated thus making them Ideal conduits for mineralizing fluids. Mineralization favored the more reactive sedimentary and volcanic rocks of the upper plate. Three gold deposits, located in upper plate rocks, are currently being mined along the Colorado River corridor: the Picacho Mine near Yuma, Arizona, 70 mi south of the study area; the American Girl Mine In southeastern California, 60 mi southwest; and the Copperstone Mine near the southern end of this study area. Samples from the above three mines were used to create a geochemical model of detachment-related gold deposits. Antimony, arsenic, barium, copper, mercury, molybdenum, manganese, tungsten, and zinc all occur In the mine samples in concentrations at least three times greater than found elsewhere in similar rock types. Samples taken by the Bureau from the wilderness study areas contain similar anomalous concentrations of the same elements as well as elevated concentrations of several other elements Including: lead, fluorine, cerium, uranium, and samarium.

Jan 1, 1992

This report is the 21st in a series summarizing research and technologic work on coal and related investigations by the Federal Bureau of Mines - the Chard of the series published on a calendar-year basis 2/ Subject publica¬tions of the Bureau during 1956 are cited, and pertinent Bureau work is described briefly. The most effective method of conserving our important coal reserves is through improved technology of production and utilization. Associated problems form the program of the Bureau.3 4 5 6/ Potential production is depend¬ent on a knowledge of the quantity and quality of the reserves, and the Bureau continues to contribute information on this subject. Many problems are being studied that relate to improvements in current production, including mining methods and health and safety measures. Preparation of mined coal is necessary for its most efficient utilization. Preparation by conventional methods is being studied, as well as the development or new methods. Fundamental studies on the structure and properties of coal are necessary to insure full advantage of the special qualities of different coals. Controlling factors in the efficient use of coal in combustion, carbonization, gasification, and direct and indirect hydrogenation of coal are being studied continuously, and new processes are being investigated. The many advances in all these fields are discussed.

Jan 1, 1959

By W. A. Young

Bull Lake is one of several saline lakes situated a few miles north of Rawlins, Carbon County, Wyo. (figs. and 2).. The Bureau of Mines conducted preliminary investigations of sodium sulfate deposits in many of the lakes and performed detailed work on Bull Lake. This investigation consisted of drilling 11 vertical holes through salt beds using diamond core bits and Iwan-type auger bits. Bull Lake lies in a shallow, closed depression in loosely consolidated sand. The salt beds, ranging in thickness from 2.5 to 26 feet, occur above a thick bed of shale of upper Cretaceous age. The salts appear to have been deposited in the lake from surface and subsurface drainage. The source of salt is undoubtedly the enclosing sedimentary rock's exposed to the west of the basin. Sodium sulfate in the deposits probably is present as mirabilite or Glauber salt (Na2SO4-10H2O). Chief impurities in the deposits arc mud and sand. Other soluble salts present average approximately 1 percent combined. Cores from the 11 holes were analyzed in the Bureau of Mines laboratories at Salt Lake City. Drilling totaled 512 feet. Results of analyses are given in the appendix.

Jan 1, 1951

By R. K. Collings

"This paper summarizes research that was done at the Mines Branch, Ottawa, to evaluate samples of phosphogypsum for gypsum products manufacture. The samples were from phosphate fertilizer facilities at: Port Maitland, Ontario ; Valleyfield, Quebec; and Fort Saskatchewan and Redwater, Alberta. All samples were wet-screened, washed, filtered and calcined in a laboratory kettle at atmospheric pressure. Tests were also made at higher pressures in a small autoclave. The gypsum and resulting hemi-hydrate, being acidic, were treated before, during and after calcining with various bases. The hemi-hydrate products were checked for time of set, compressive strength and bond to gypsum wallboard paper. The results of this study indicate that phosphogypsum from each of the sources investigated has potential as a substitute for mined gypsum in gypsum products manufacture. Pilot-scale testing is recommended to confirm that the product would be satisfactory for the manufacture of plaster products on a commercial basis."

Jan 1, 1972

During the last 20 years, manufacturers of Australian iron have given increasing attention to development of external markets for processed blast furnace slag. Slag has been in widespread use overseas and data on the performance of Australian slag in concrete lave shown it is suitable for that use. Chemical and physical properties of typical Australian slag products including air cooled, granulated and pelletised slag are discussed and compared with local natural aggregates. Special attention is given to pumping achieve- ments with slag concretes and the observed durability of concrete after many years service. More'recent applications for granulated slag as a sand replacement are discussed. It is concluded that'whilst more wide- spread use of slag is possible, the cost of marketing and transporting slag are likely to restrict opportunities unless for local usage.

Jan 1, 1979

By S. E. Khalafallo

The Bureau of Mines investigated the kinetics of reduction of wustite and magnetite with carbon monoxide. A mechanism was postulated wherein the interaction between gaseous and absorbed carbon monoxide appears to be the rate-determining process. This mechanism fully accounts for the experimental rate equation JL.h relates th velocity of reduction to the pressure of the reducing gas at constant temperature. It also explains the variability of the heat of activation of the reduction process with the state of aggregation of the oxide material. The integrated rate equation is in perfect agreement with the experimental reduction-time curves.

Jan 1, 1966

Prevention of coal-mine explosions depends largely upon thorough knowledge of the causes that initiate explosions. A review of coal-mine explosions in one geographical area when supplemented by nationwide data of similar nature, should serve as a guide for the adoption of measures for explosion prevention. Explosions in bituminous-coal mines of the United States during the 10 years ended December 31, 1932, ranked third in the causes of fatal accidents and constituted 16.1 percent of all fatal accidents in bituminous mines. Kentucky now ranks fourth in coal output in the coal-producing States of this country; a study of the coal-mine explosions in this state will be of definite interest locally among coal-mining people, as well as to those in the coal-mining industry who are concerned in preventing coal-mine explosions. This circular reviews gas and dust explosions in Kentucky coal mines to show their hazards, to point out the influence of certain factors in causing explosions, and to indicate the effectiveness of preventive measures.

Jan 1, 1934

By E. A. Magill

The Bureau of Mines has begun a study of the copper resources of the Cascade Mountains of Washington. The program includes reconnaissance of mineralized areas and examination and occasionally limited exploration of deposits that are considered characteristic of an area. The Bureau of Mines believes that published information may assist industry in searching for new sources of copper. The Miners Queen is one of a few Cascade Mountain deposits selected for prelim¬inary exploration. The investigation was not planned to delineate the ore body. A diamond-drilling program was carried out at the Miners Queen mine in the summer of 1955. Five diamond-drill holes were completed, totaling 628 feet. Two 35-foot shafts were dewatered, and all accessible underground and surface workings were examined.

Jan 1, 1957

By Steven A. Fechner

In 1984 the Bureau of Mines cunducted mineral investigations of specific sites within the Yentna Mining District. One hundred eight placer and rock samples were taken. Reconnaissance placer samples were collected from drainages in the Talkeetna, Susitna, and Yentna River basins. The highest placer gold values were found in the historic placer gold producing creeks of the Cache-Peters Creek area. Samples taken from an outcrop in the Middle Fork of Iron Creek in the Talkeetna Mountains contained previously unreported high lead, zinc, and silver values.

Jan 1, 2011

By Frank D. Lamb, D. A. Woodard

"INTRODUCTION The iron-ore deposits near Cranberry, N. C., were worked as early as 1820, and records show that to date at least 1,500,000 tons of ore has been mined.. The early operators depended on selective mining and hand cobbing to yield a product containing 40 to 50 percent iron. Later, a magnetic concentrator was erected by the Cranberry Furnace Co. and was operated periodically until 1930. The magnetic cobbing method employed yielded satisfactory concentrates, but the plant was shut down because costs were too high. 4/Early in 1944, in connection with the sponge-iron program of the Bureau of Mines, North Carolina and Tennessee were surveyed for the purpose of finding a readily available source of high-grade iron ore for use in the experimental production of sponge iron at Salisbury, N. C., and samples from various sources were tested in the laboratory. The Cranberry ore proved to be best with respect to grade of magnetite concentrates produced, and it was decided that a pilot mill should be built on the Cranberry mine property and that the concentrate made there should be shipped to Salisbury for direct-reduction tests in a commercial brick kiln."

Dec 1, 1946

By William F. Boericke

KIRKLAND LAKE and Porcupine in 1931 accounted for more than $41,625,000 of Ontario's total gold production of $43,117,688. For the first time, the younger camp surpassed the older in gold output, producing $21,734,000 against $19,891,000 for Porcupine. Present output of both camps is increasing, and should pass the record figures of 1931 before the year is out. In May of this year, Porcupine mines milled 285,759 tons, with a bullion value of $1,810,009; the corresponding figures for Kirkland mines are 149,188 tons and $2,104,757. A much higher average value per ton for Kirkland ore, $14.10 against $6.33 average for Porcupine accounts for the difference. The two fields are about 100 miles apart by rail, and there are important differences in the character of the ores, which accounts largely for the difference in milling costs and in final tailing values, despite excellent metallurgical work in both the fields.

Jan 1, 1932

By T. F. Anstett

The Bureau of Mines evaluated the potential availability of chrysotile, amosite, and crocidolite asbestos from 42 properties in market economy countries. This resulted in the development of tonnage-cost relationships indicating the quantity of grades 3 through 7 asbestos at various average total costs of production at 0% and 15% rates of return on invested capital. The availability of grades 2 and 8 was also evaluated, but since each is produced at only one property, no analytical results were given. Total demonstrated recoverable chrysotile fiber potentially available of grades 3 through 7 from the 42 properties evaluated follow: 1.59 million t, 21.00 million t, 16.74 million t, 15.54 million t, and 19.27 million t, respectively. The total amount of crocidolite is 1.69 million t. Owing to the good potential for discovery and development of new deposits, long- term availability of fiber of all three types is not in jeopardy. However, many of the crocidolite properties evaluated in the northern Cape crocidolite field of South Africa have relatively small demonstrated resources, and new deposits will have to be exploited by the late 1990's to sustain projected levels of production.

Jan 1, 1985

By A. Suarez, M. Menendez, M. R. Gent, P. Riesgo

"Recent requirements to reduce thermal coal plant emissions, and ultrafine coal's tendency to produce these emissions due to its typically high ash and moisture contents have limited the use of ultrafine coal. Ultrafine coal in beneficiation plants are usually either disposed of in tailing ponds at a loss in combustible material or disposed of by blending with coarser higher-grade products, resulting in a reduction in marketed product quality. A study of the options for processing ultrafine coal, consisting of < 200 µm hydrocyclone overflow, with 38.8 percent ash content is presented here. Ultrafine coal was processed based on 200-µm sieve bend and 10-µm hydrocyclone classifications, enhanced gravity separation (EGS) and froth flotation concentration as well as combinations of these. Yield, combustible material recovery (CMR) and product humidity were evaluated as test results.Depending on the processing applied, product ash content could be reduced up to 49.7 percent, and up to 95.8 percent CMR of the actual run of mill feed could be attained. All of the processing options analyzed could reduce produced thermal electric plant emissions due to ash and moisture from 22 to 38 percent of the actual unprocessed ultrafine coal product.Froth flotation was found to be the optimal process, yielding a product with the lowest ash content attained of 19.5 percent and CMR of 92.3 percent. Being the most versatile of the processes evaluated, it is capable of producing coal with varied ash contents but is subject to potential variations in coal flotability. The most complicated of the processing options, a combined sieve bend recovery of the > 200 µm fraction and EGS processing of the 10 to 200 µm fraction was found to be the next best option, attaining a combined 90.1 percent CMR and 25.0 percent ash content. IntroductionMunicipal, regional and national objectives to reduce fossil fuel combustion emissions and their effects on air quality and global weather changes are affecting thermal electric plant operations. Plans and regulations such as President Obama's Clean Power Plan (U.S. Environmental Protection Agency, 2015), the European Directive 2010/75/EU (European Commission, 2010) and China’s proposed Enhanced Actions on Climate Change (Wei, 2015) are of major significance to thermal electric plant operations. Although thermal plant efficiencies depend in large part on the losses of heat by plant components, the ash and humidity contents of thermal coal invariably reduce plant efficiencies and increase emissions of carbon dioxide (CO2), nitrogen oxides (NOx) and dust.Any noncombustible material present in thermal coal will result in higher CO2 emissions per unit of energy produced. Since no particle emission control can be totally effective, it is to be anticipated that any reduction in coal ash content will also result in reduced particle emissions. Kurose, Ikeda and Makino (2001) reported that NOx emissions also increase with coal ash content. The effect of coal moisture content during combustion is complex. Kurose, Ikeda and Makino (2001) showed that an increase in coal moisture content significantly reduces thermal NOx to total NOx production, and Bosoaga et al. (2006) showed that it tends to reduce NOx emissions. Since the humidity, pyrite and ash content of thermal coals directly affect thermal electric plant efficiencies and emissions, minimizing these factors should facilitate, at least in part, compliance with thermal electric plant emission limits. This, in turn, would affect the specifications and prices of the coal preparation plant products."

Jan 1, 2016

By C. H. Elder

A 5-hole pattern was drilled from the surface at a site near Oak Grove, Jefferson County, Ala., to degasify the gassy Mary Lee coal bed in advance of mining. Gas and water production was monitored for 1 year, 4 months to allow gas flow to stabilize fully. A thickened water stimulation treatment was designed and applied in one hole of the pattern to evaluate this degasification technique for the Mary Lee coalbed. A gas production rate of 70,000 fts/day after stimulation treatment indicates that the use of vertical boreholes coupled with hydraulic fracturing in advance of mining the Mary Lee coalbed would provide for more rapid degasification and could provide a possible source of natural gas.

Jan 1, 1974

By Kimio Itagaki

The distribution behaviours of the VA elements between the gas, slag and matte phases in copper smelting were evaluated on the basis of the thermodynamic data, most of which were determined by the authors. The distribution is basically dependent on the process factors such as temperature, the content of the element in charge, the amount of the waste gas and degree of vapour saturation with the elements. The thermodynamic quantities such as the activity coefficients of the VA elements in matte, the activities of iron and copper, SO2 or 02 potential and the distribution ratio of the elements between the slag and matte phases seriously affect the distribution, and the behaviours in various smelters could be explained systematically and reasonably by considering the changes in these quantities, In oxidation smelting at PSO2= 0.1 to 1 atm, the proportion of arsenic and bismuth in gas is predomi22t for the arsenic and bismuth distributions in both smelting and converting stages. The degree of vapour saturation has serious effect on the distribution, and sufficient contact between gas and matte phases is desirable for transferring arsenic and bismuth into gas phase.The elimination of antimony by means of vaporization is not significant. In reduction smelting at po2 = 10-11 atm, the proportions of arsenic and antimony in the gas phase are quite small, but the proportion of bismuth does not change significantly.

Jan 1, 1983