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By Michael J. Beus

This Bureau of Mines report describes a field experiment involving the sinking of two test shafts to directly compare the deformational behavior of circular and rectangular shapes. Results show that the circular shape is less sensitive to geologic discontinuities and applied stress field. Also, the rectangular shape is subject to a variety of behavioral modes, including beam bending and buckling. Geologic discontinuities around circular and rectangular shapes influence displacement significantly. Simple, two-dimensional elastic finite-element modeling, simulating circular and rectangular shapes in a biaxial stress field, shows that the structural response of a shaft is largely controlled by geologic structure. Consideration of anisotropy may be required for realistic analysis of a deep shaft.

Jan 1, 1985

By James F. O?Neil

Brown iron ore deposits in Quitman County, Ga., were investigated by the Federal Bureau of Mines in cooperation with the State of Georgia, Department of Commerce, and the University of Alabama. Ninety-one holes were drilled, having an aggregate footage of 2,188 feet; seventy-one holes penetrated 248 feet of iron mineralization. Average thickness of the ore zone was 3.5 feet under an average thickness of 14.7 feet of overburden. The drilling developed inferred reserves containing nearly 30 million long tons of crude ore with an average analysis of 28 percent iron plus minor quantities of manganese. Test work done by the Bureau on the crude ore samples indicated that they would upgrade by current lug washer practice, with the use of a 1i8-inch screen, and yield 4.4 million dry long tons of concentrate with an average analysis of 52.1 percent iron plus manganese. The weight recovery obtained was 14.7 percent. Research studies made by the Bureau showed that the weight recovery would be increased by changing the screen size without any appreciable sacrifice of grade. The average weight recovery was increased to 18 percent with a 10-mesh screen and 22.8 percent with a 20-mesh screen. Screen tests studies indicated that there was no appreciable interlocking of the iron and manganese minerals and the clay and silica waste particles of the materials retained on a 200-mesh screen. Clay was prominent in micron-size slimes. Silica was deleterious in the minus 20-mesh size.

Jan 1, 1965

By C. W. Van Law

WE have just heard a very able presentation, by Mr. J. C. Cameron, on the subject of Recent Trends in Labour Relations, as they exist today in Canada (l). With minor changes, what he said applies equally to the situation in the United States. Direct negotiation between employer and employee on a man-to-man basis, wherein good faith and mutual esteem was at least sometimes a factor, has almost entirely given way to a mass struggle in which each side is represented by highly trained specialists in a new jurisprudence, built up on vote-getting labour laws, decisions in analogous cases by Boards whose members may have had very little personal acquaintance with the specific case, etc., etc. Membership in a labour union has become almost an essential requisite to a job; once in, the individual workman loses his identity and dares not act on his own initiative or even express any idea not handed him by his Union head. An honest workman cannot turn in an honest day's work, because his Union will not allow him. Leadership in the Unions has become so powerful an instrument, both politically and monetarily, that Union policies are drafted primarily to build up that power, and may have little relation to the equities of the individual case. ?While both sides still render lip-service to the doctrine that Capital and Labour can advance best by co-operation to mutual benefit, that doctrine has in effect given way to as bitter and as legalistic a struggle as any in our civil courts. There are many reasons to believe that we are, industrially, in a situation much like the European situation from 1935 to 1939; an impending war to the death with 'appeasement' as the only, unavailing, policy

Jan 1, 1945

By H. W. GILLETr, E. L. Mack

The production of small heats of alloy steels on an experimental scale is often desirable in beginning the study of new alloy steels before large amounts of expensive alloys are used in heats of commercial size. Such small heats can sometimes be made up at crucible-steel plants, but few crucible-steel makers care to undertake experimental heats for other firms. Small electric furnaces offer some advantages over crucible furnaces for experimental work. Hansen1 in 1909 described a small 100-kilowatt single-phase, direct- arc furnace with a capacity of 50 to 300 pounds of steel, and such furnaces, of 200 pounds capacity or larger, are being successfully used by various firms for experimental work. They have the advan- tage of using the same metallurgical procedure as is used in prac- tice for larger electric furnaces. The very small sizes have the draw- back of lack of precision in controlling the carbon content of the steel. Small Rennerfelt two-phase, indirect-arc furnaces of 40 to 60 kilo- watts and small Industrial Electric Furnace Co. furnaces, single- phase with one electrode embedded in the hearth, of 25 to 50 kilo- watts, are also in use by a few firms for experimental work or for production on a very small scale. Hoskins carbon-plate resistor crucible furnaces are also sometimes used. Little seems to have been published on the use of these furnaces in making experimental alloy steels. Keeney' has given data on the making of uranium steels in a tilting Siemens furnace of 25 pounds capacity, and has described a small stationary Siemens furnace.

Jan 1, 1922

By C. Edward Chamberlain

A Bureau of Mines procedure was developed for the analysis of volatile matter in airborne coal dust-rock dust mixtures prior to, and resulting from, coal mine fires and explosions. Dust in the 10-to 20-mg weight range can be analyzed. Volatile matter is determined by a greatly scaled-down version of the empirical macro-scale method used by the Bureau. The alkaline earth carbonates in the rock dust are dissolved in acid prior to the volatile matter determination of the residue, and the rock dust content is calculated from the analysis of calcium and magnesium by atomic absorption.

Jan 1, 1974

The National Institute for Occupational Safety and Health (NIOSH) conducted field tests to evaluate the effectiveness of a wet head continuous mining machine for reducing dust exposure for continuous miner operators. Wet head technology delivers water via sprays to the continuous miner?s cutter head as opposed to traditional standard sprays located on the boom and body of the mining machine. The sprays, positioned directly behind each bit on the cutterhead, deliver water at the point of attack, serving to cool the bits during mining to reduce the potential for frictional ignitions. The sprays also flood the coal with water to potentially suppress dust generation. Dust surveys were conducted at several mines to evaluate the wet head?s effectiveness to control respirable dust exposure at the continuous miner operator location and in the immediate return. Results show that the wet head miner generally improved air quality at both sampling locations to varying degrees in some, but not all, mines when compared to a continuous miner with a standard spray system.

Jan 1, 2010

By Jukka Tuominen

The history of making blister copper in an Outokumpu Flash Smelting Furnace dates back to the late 1960?s, when Outokumpu first piloted the Outokumpu Direct Blister (ODB) process. The first commercial scale applications have been in use at Glogow, Poland, since 1978 and at Olympic Dam, Australia, since 1988. These applications utilize special concentrates, which are low in iron, and thus the formation of slag is also low. In 1995 the same principle was applied to smelting copper matte into blister copper in industrial scale at Kennecott Utah Copper. This application, the Kennecott-Outokumpu Flash Converting process, will celebrate its 10th anniversary of commercial scale operation this year. This paper outlines the development in efficiency and flexibility of Blister Flash Smelting processes compared to other smelting and converting options. The focus is on the economical aspects i.e. on the total feasibility of both greenfield investment projects and revamping of existing smelters.

Jan 1, 2005

By K. S. Fraser, R. Frischmuth

High temperature pressure oxidation (>190°C) is a wellrecognized and versatile metallurgical oxidative pre-treatment process commonly used to liberate gold from refractory sulfide ores and concentrates. The pressure oxidation of refractory gold ores was first commercially applied in 1985, at Homestake Mining Company’s McLaughlin mine in the United States. Since that time numerous refractory gold and other high temperature pressure oxidation facilities have been built throughout the world. The design of each facility was met with unique challenges and opportunities which have led to an array of plant configurations, pressure oxidation autoclave sizes, and sulfide oxidation capacities. This paper presents a historical review of high temperature pressure oxidation operations and current projects in execution with a focus on the autoclave vessel design, circuit configuration, and unit sulfide oxidation capacity as a basis for characterization and comparison.

Mar 2, 2022

By LUDWIG VOGELSTEIN

WE are indebted to Mr. Barbour for his valuable contribution to the literature on copper statistics; it is to my knowledge the only intelligent attempt to throw light on a much misunderstood subject. If I should appear to criticize some of his findings and arguments, I do not want to leave the impression that I do not appreciate the article; I think Mr. Barbour has been painstaking, and even where one might not agree with his conclusions, he has opened our eyes and stimulated us in our search for the truth.' It might be well to define the term "secondary copper" and to make a few remarks about the origin and the reasons for the variation of the supply. Mr. Barbour has touched on these points, but not sufficiently to make them clear to those not in the business.

Jan 1, 1931

By E. Shum, V. G. Papangelakis

"Attempts to reduce the energy requirements of water recovery in the process industries have resulted in the development of techniques to freeze and purify aqueous solutions that take advantage of local climatic conditions. Natural freezing is a technique by which aqueous solution is exposed to freezing air temperatures, resulting in the production of a layer of ice on the surface. As the ice layer tends to exclude solute, a concentrated solution is formed. However, due to dendritic ice growth along the advancing growth front, small quantities of solution are trapped within the ice, decreasing the purity of the water recovered. The ice produced can then be allowed to thaw in order to recover the water using low grade plant heat. As the more concentrated parts of the ice melt first, a purer ice remains. In this study, 0.5 molal magnesium sulfate solution was frozen under simulated natural freezing conditions at temperatures between –1 and –6°C. The ice produced was thawed at either room temperature or 50°C. Up to 40% of the water was recovered with a separation efficiency of above 95% when thawing at room temperature.INTRODUCTION Advances in refrigeration technology have made low-temperature separation processes increasingly appealing to an energy-conscious society. The latent heat of freezing of water is about seven times smaller than the latent heat of evaporation providing freezing with a strong thermodynamic advantage over the traditional evaporation-based processes. The result is the development of a wide variety of processes that fall under the term Freeze Concentration (FC), which describes a variety of techniques in which an aqueous solution is concentrated by the creation and subsequent removal of ice (Williams et al., 2015).FC processes exploit the freezing behaviour of aqueous solutions as dictated by their respective water-salt phase diagram. When, for example, a solution of magnesium sulfate is cooled to a temperature below its freezing point but above its eutectic temperature of –4.1?C (Figure 1) then, if the concentration of MgSO4 is less than the eutectic concentration (about 1.7 m), ice will form until the solution concentration reaches its equilibrium concentration at the given temperature on its phase diagram. If the concentration is greater than the eutectic concentration, MgSO4 solid will precipitate until the concentration reaches equilibrium. It is for this reason that ice can be selectively produced in FC processes (Randall & Nathoo, 2015)."

Jan 1, 2017

By W. A. Lang

"I.-IntroductionAn attempt bas been made in this paper to provide a basis for appraisal of the future of the coal briquetting industry in Alberta by outlining the processes used for briquetting various ranks of coal, by specifying the requirements of a briquetted fuel, by indicating .the status of the industry in the United States, by giving developments in Western Canada, by assessing costs of processing, and by discussing briquetting researches in progress. Much of .the detail bas been omitted since this might mask, rather than reveal, the more important phases of the problem. Reference will be made when possible to published articles where many of the details can be obtained.It should be stated at the outset that, in the writer’s opinion, there are three possible developments in Alberta as regards briquetting: (a) an expansion of the briquetting of the fines of • non-coking and coking coals of semi-anthracite, and of low and medium volatile bituminous rank; (b) the processing of the fines of high-volatile C bituminous coals; and (c) the upgrading of the lower rank high-moisture sub-bituminous coals. Details of the chemical and physical properties of these coals can be obtained in publications of the Research Council of Alberta (1, 2), and of the Fuel Research Station, Bureau of Mines, Ottawa (3).Semi-anthracite and low and medium volatile bituminons coals occur in the mountain areas of Alberta, where, during the upthrust of the Rocky mountains, the coal beds served as the sliding surface. This resulted in the coals being; crushed and consequently they contain a h1gh percentage of fines. In some cases they are high in mineral matter and require to be cleaned before being processed. However, the cleaning of fine coal is both difficult and costly. Both the amount of fines present in the mine-run coal and the amount of mineral matter associated with the coal have increased through the introduction of mechanized mining and through the recovery of coal by stripping operations."

Jan 1, 1950

By S. E. Younis

The mining industry is currently looking to better understand, anticipate, and be able to mitigate business and operational risks in order to deliver the rewards of risk taking, and to minimize the frequency and impact of risk on the downside. Assessing risk works from the premise that the identification and management of existing risks can be very challenging, especially when threats are not easy to detect, the likelihood of occurrence is difficult to gauge, and/or the consequences are uncertain. Some approach this as a ?check the box? task, even though fire and safety incidents continue to occur and investigations often find the hazard analyses did not properly identify the cause or consequence. You cannot engineer protective designs and safeguards for causes and consequences that have not been identified appropriately. For the mining industry, risk management is an important tool for making critical decisions and, in some cases, meeting regulatory requirements. Providing high-quality documentation that meets both regulatory and corporate requirements is critical for maintaining safe, uninterrupted mining operations. Risk management is a five-part process: 1. Identify the hazards and their causes, 2. Determine the hazard consequences, 3. Calculate the frequency of occurrence, 4. Quantify the risk associated with the system, process, or procedure, and 5. Provide feasible solutions for the risks

Jan 1, 2012

By J. Gotor, C. Frias, E. Delgado

The Iberian Pyrite Belt (IPB) is one of the world's largest reserves of primary sulphides containing base metals (Cu, Zn, Pb), precious metals and some special metals such as indium. Estimated resources are over 1,500 million tonnes of volcanogenic massive sulphide ores. From 1980´s Europe lives the decline in its mines mainly motivated by the low price of the metals. One aspect that contributed equally to this was the ecological disaster produced by the discharge of more than seven million tonnes from the tailings dam of Boliden-Apirsa (Aznalcollar) in 1998. Today the situation is different; the companies present in the IPB have given evidence that it is possible to reconcile mining projects and care on the environment, and the regional authorities are opening a public tender to re-start Aznalcollar mine. A new challenging era has been started at this Spanish/Portuguese mining area. This paper presents the results and preliminary economics of a project devoted to IPB primary sulphides processing through different technology approach, e.g. conventional selective flotation against bulk flotation or mixed metals flotation combined with hydrometallurgical processing.

Jan 1, 2014

By Xinghai Lei, Nan Wang, Xiangyang Jin, Yuqi Ren, Yang Li

The upward mining method, as an effective mining method, is widely employed in close-multiple coal seams to extend the service life of coal mines and improve the recovery rate of residual coal resources. However, the upward mining feasibility of the upper coal seam is related to the height of caved zone of interlayer strata after lower coal seam extraction. Therefore, it is extremely important to determine the height of the caved zone after the lower coal seam. The No. 9 coal seam (upper coal seam) and the No. 12- 1 coal seam (lower coal seam) in the Qianjiaying coal mine are selected as the research object. The characteristics of the interlayer strata structure field, fracture field, and subsidence field are studied using UDEC numerical modeling, in which the height of the caved zone is gotten after the No. 12- 1 coal seam extraction. Furthermore, the height of the caved zone is verified by onsite detection of GPR and BTVI. In the numerical modeling, the height of the caved zone is 19.6 m. And the height of caved zone is 14.7 m and 15.4–21.2 m, respectively, by using the onsite detection of GPR and BTVI. The heights of the caved zone onsite detection results are consistent with the numerical modeling result. The No. 9 coal seam is always located above the caved zone after the No. 12- 1 coal seam extraction. Consequently, the upward mining of the No. 9 coal seam is feasible.

Jun 28, 2023

By G. L. Oldright

[This paper is the fifth 4/ of a series of publications on smelting in the load blast furnace. The objects of this investigation are to determine the conditions obtaining within the blast furnace by direct experimentation, and to correlate the behavior of the furnace at various tines with the main factors governing the operation of the blast furnace, and metallurgical losses.]

Jan 1, 1929

By Horst H. Gielen

Bong Mining Company/Liberia provides the rare opportunity to compare two generations of grate kiln pelletizing plants operating on the same magnetite/hematite ore basis. In this paper advantages and drawbacks are compared: mechanical aspects, energy-savings, pellet quality. Plant I with up- and down-draft drying gas flow. Plant II runs only on down draft drying and incorporates a heat-recoup system. Ferteco Mineracao/Brazil operates a Lurgi straight grate plant since 1977 on hematitic pelletfeed. Energy-political situation and char- coal as energy source in Brazil are reflected also in the search for alternative fuels for pelletizing. First measures and results are reported as well as intended further steps towards a 100 % oil replacement.

Jan 1, 1983

By M. H. Chetrick

Since 1945, a commercial-scale pilot plant for the gasification of lignite has been operated by the Bureau of Mines at Grand Forks, N. Dak. The description, operation, and objectives of this pilot plant have already been described in previous reports (6, 7, 8). Although the experimental data obtained from the operation of the externally heated retort have been tabulated and summarized (1, 7), few studies have been made in the correlation of these data. The purpose of the present investigation was to review the data taken in tests of the lignite-gasification pilot plant and to correlate the gas-composition data in terms of their basic factors.

Jan 1, 1950

By M. J. Latva-Kokko

This paper describes the behaviour of iron and the methods used for iron control in the nickel matte leaching process. OMG Harjavalta Nickel Oy processes approximately 10 000 t/y of iron, which enters the process with the nickel matte raw material. Iron dissolves and precipitates in several different stages of the leaching process. Compounds like ferric hydroxide, parabutlerite, goethite, hematite and jarosite are found. Iron removal is done within the leaching process, and this means that the dissolution of nickel sets the limiting conditions for iron precipitation. A leach residue consisting mainly of the iron precipitates is neutralized and stacked in the waste pond. When iron is precipitated from concentrated nickel sulphate solution, some nickel is lost by co-precipitation. Recent studies have shown that Ni-Fe ratios less than 1%, attributed to co-precipitation, can be obtained with jarosite precipitates, compared to 2-3% ratios typically found with hematite precipitates. Iron can be precipitated as jarosite under the optimal nickel leaching conditions by adding ammonium sulphate to the feed slurry of the autoclave.

Jan 1, 2006

By K Morrison

Australia’s ageing population means that by 2050 there will be 2.7 people of working age to support each Australian aged 65 years and over compared with five working people per retiree today and compared with 7.5 in 1970 (Swan, 2010). This means that there is going to be a greater demand on social services – for medical and aged care – from a smaller private income base. How will this gap be met? Australia is fortunate in that it has vast resources of mineral wealth; from iron ore, nickel and gas in Western Australia to the giant copper and uranium deposits at Olympic Dam in South Australia.The prospect of a meaningful profit based tax on this vast mineral wealth has been lost through Australian government’s handling of the issue in 2010 and with an industry fiercely opposed to the prospect of a mining tax. Hence, new ways of thinking are required. This paper looks at the issues facing the implementation of a novel scheme whereby Australia leases the mineral resources it extracts and thus derives income over the decades the metals are in-use in pipes, wires and structures with a premium paid for unreturned material or that used in dissipative applications. Applicable minerals could include copper, aluminium, nickel and rare earths. If Australia simply digs up and sells the metals once, the buyer becomes custodian of that resource and they benefit from controlling the future ‘above-ground’ resource stock.A complementary driver for a leasing scheme is the increasing importance of chain-of-custody following initiatives of the Responsible Jewellery Council with gold and diamonds, now with the potential to extend across commodities. The Australian minerals sector could thus position itself as a premium supplier with high social and environmental credentials.Recognising the implementation challenges, this paper includes a review of how such a system could be enforced to ensure that the metal is tracked throughout its life. It concludes with a discussion of the rates and terms should such agreements hold and suggestions for institutional arrangements for enforcing compliance.

Nov 22, 2011

By A. J. S. Spearing, A. Mueller

The support of intersections in coal mines remains an important safety issue, mainly because the large diagonal span compromises the stability of the roof. This structural weakness is further exacerbated if the intersection is developed incorrectly, the pillar corners fail or the crosscuts are angled (not perpendicular). This report details the current support systems used and investigates unplanned falls of ground in intersections in coal mines throughout the United States. A possible failure mechanism is proposed and some suggestions are made to improve the effectiveness of the support in these vital areas.

Jan 1, 2009