Search Documents

By Alvin Kaufman

Increased exploration in Alaska has resulted in many requests to the Bureau of Mines for facts about the mineral resources and mining conditions in the Territory. This report presents information about the minerals of Southeastern Alaska and the factors that affect development of a mining industry in that area. Southeastern Alaska is a narrow coastal strip of rugged mountains and many islands. The climate is mild, with an average annual temperature of 40° and heavy rainfall. Geologically, the region is favorable for deposition of ore; geographic-ally, it is difficult to prospect and to develop, except along areas immediately adjacent to the coastline.

Jan 1, 1958

By Xin Wang, He Shao, Wenpu Li, Yiyi Zheng, Xi Chen, Yurong Gao

This study utilized experimental and numerical simulation methods to investigate and analyze the atomization characteristics of three internal air–water mixed atomizers under different operating conditions. By comparing the research results, the effective dust control working parameters for the application of the selected atomizer in the engineering field were determined. Firstly, the atomization characteristics of the three atomizers were studied using a customized experimental system. The results indicated that nozzle 2 had a wide atomization range, a small atomization distance, and small droplet size; nozzle 3 had a narrow atomization range, large droplet size, and fast atomization speed; and nozzle 1 not only had a large atomization range but also could produce droplets of dry mist size with fast atomization speed, meeting the dust reduction requirements of the Majiliang Coal Preparation Plant. Secondly, Fluent software was used to simulate the atomization process and particle size distribution of the three internal mixed atomizers, determining the working conditions of the atomizers, the required number of atomizers, and the application angle of the atomizers in the internal mixed dust removal system. Finally, the atomized dust control system was applied on-site, achieving a total dust removal efficiency of 90.72% and a respirable dust removal efficiency of 89.75%.

Mar 9, 2024

By S. K. Sahoo, S. K. Sharma, A. Yadav, B. Behera, G. S. P. Singh

A field representative modeling of the gob behavior is critical for the understanding of the associated mechanics of strata behavior in longwall workings. The findings of theoretical models and laboratory tests on the simulated gob material have shown the strain hardening behavior of the gob material. The double-yield material model, which is a built-in constitutive model in FLAC3D, has significant potential to simulate the gob compaction process as it represents materials which undergo irreversible compaction in addition to shear yielding. Apart from this, several researchers have attempted using modified elastic model or applied nodal force in reaction to the strain in the gob area as per the well-known theoretical relations to meet this requirement. Although these models can simulate the mechanical response of the gob for subcritical and critical extraction widths, they do not apply to supercritical extraction width as the gob stress may exceed the in situ stress level in such cases. For overcoming these limitations, a standard approach has been developed and validated in this paper, which can be used for simulating the gob behavior in supercritical longwall workings as well. The complete study is divided into two stages wherein the laboratory scale compression test on the simulated gob material has been numerically replicated to develop preliminary confidence followed by a parametric study of the double-yield constitutive parameters for a rational estimation of their values in different conditions. The calibrated model has been used for verifying its results by plane strain modeling of two different longwall workings, using well-established empirical and analytical findings and field observations. The approach suggested in this study can be used for the efficient modeling of the gob behavior of longwall panels under varying geo-mining conditions without compromising the accuracy of the numerical model. The meticulously validated model can be helpful in rational estimation of stress redistributions around the gob area apart from load transfer on the barrier pillar.

By Larry A. Haas

The chemistry of current or potential SO2 removal processes can be placed into four categories: (1) reduction, (2) Liquefaction, (3) direct dissolution, and (4) oxidation. Methods that involve reducing SO2 to elemental sulfur appear promising since this product can be easily handled, shipped, and stock- piled. Unfortunately, SO2 cannot always be reduced directly when other oxidizing agents are present. Thermodynamic data indicate that some oxidizing reagents will also consume reductant at the reduction temperature. A two- stage process can be applied to waste gases that contain excessive quantities of oxygen, nitrogen oxides, and water vapor. The best sorbent for the first stage appears to be a nonalkali or nonalkaline earth medium since this medium more readily releases the SO2 for reduction in the second stage.

Jan 1, 1973

By R. E. Cerullo

Many computer programs have been written which are capable of performing a least squares fit, both linear and nonlinear, to data gathered by the petroleum researcher. However, when the petroleum engineer tries to program methods of analysis he has used manually in the past, such as forecasting production by decline-curve analysis, more than a knowledge of the use of existing least squares programs becomes necessary. It is the intent of the authors to report the techniques used in the development of such a decline-curve program.

Jan 1, 1970

By J. Roger Loebenstein

This report presents a U.S. Bureau of Mines study of the flow of arsenic-containing materials in the United States, based on the best data available in 1991, includes a consideration of arsenic as a byproduct of the processing of nonferrous metals, the fate of arsenic in manufacturing wastes, the quantity of arsenic used in products, tile fate of arsenic in dissipative uses, and the useful life of discarded products. Where possible, estimates are given of the amounts of arsenic lost from the materials flow. Arsenic byproduct of mining nonferrous metals. Historically, most U.S. production has been from the states of Montana, Washington, and Utah. The smelters in these states are believed to be the areas of the country where arsenic is most concentrated in the soil, tailings ponds, and waste dumps. Since the closure of the last domestic producer of arsenic in 1985, all arsenic has been derived from imported sources. Historically, arsenic was important in agricultural applications as an insecticide, herbicide, and cotton desiccant. As the environmental movement gained momentum and the toxicity of arsenic became better understood, most of the agricultural uses for arsenic were banned. Beginning about 1975, the use of arsenic as a wood preservative began to grow. After 1980, wood preservative uses became more important than agricultural applications. By 1990, 70% of the arsenic consumed in the United States was used by the wood preservative industry and 20% by the agricultural industry. The major source of domestic arsenic emissions in 1989 was from the U.S. copper processing indus¬try. About 7,800 mt/yr of arsenic was discarded in leach dumps, tailings, and slag. Another 800 mt/yr was liberated to the atmosphere and 1/100 mt/yr was exported in copper concentrates. On the consumption side, 9,200 mt/yr was lost, mostly from dissipative agricultural uses and the disposal of obsolete arsenical products.

Jan 1, 1994

As the high-grade copper deposits in the world become depleted, there is an increasing focus on developing lower-grade ores which contain problematic impurities such as arsenic. Indeed, many high-arsenic ore bodies remain undeveloped because of their high arsenic levels. Separation of arsenic from copper at the beneficiation stage is difficult using the current processing techniques and invariably copper concentrates produced from these ores contain high arsenic levels, sometimes so high as to make them unacceptable to copper smelters. New, sustainable approaches are needed to allow development of high-arsenic copper ores while at the same time minimizing arsenic dispersion into the biosphere. The most promising route for separating arsenic from copper at the flotation stage centers on the use of pulp potential control. In recent years CSIRO has demonstrated at laboratory scale, for a number of high-arsenic copper ores, that crude flotation separation between arsenic-bearing minerals and copper-bearing minerals can be made. The differences in specific minerals responses to changes in pulp potential and pulp pH are exploited for this separation. Such separations nominally produce a low-arsenic high-copper concentrate and a low-copper high-arsenic concentrate. The former can be smelted without penalty, while the latter requires further treatment to capture and stabilize the arsenic and to recover the residual copper. Consideration has now been given to treatment options for the high-arsenic low-copper product. A pyrometallurgical option, involving a low temperature roast to selectively fume off the arsenic and leave a high-copper calcine, coupled with an arsenic stabilization step, has been demonstrated in the laboratory, and a preliminary techno-economic evaluation shows the process to be economically favorable. These results were recently published. CSIRO has now investigated an alternate hydrometallurgical option, involving atmospheric alkaline sulphide leaching of the high-arsenic product, where the arsenic is selectively dissolved leaving a copper-rich leach residue. The leaching testwork was carried at on the same high-arsenic low-copper material used in the roasting studies, enabling a techno-economic comparison of the alternate roasting and leaching treatment options to be made. The alkaline leaching work is briefly described and the results of the process option comparison presented and discussed. Keywords: arsenic, copper, economics, enargite, ore flotation, tennantite INTRODUCTION

Sep 1, 2012

By R. E. Peterson

Scrap iron is partially oxidized at elevated temperatures in the selective oxidation process to produce iron oxide and a dense residual metal of high purity. Investigation of the process was confined to converting automobile hulks into useful products. In one test series, compressed, sheared automobile scrap was processed at 1,000° C in a 36-foot-long rotary kiln at feed rates ranging from 300 to 1,200 lb/hr. Less fuel was required to maintain the temperature at the higher feed rates because of the heat generated from the burning of the combustibles and the oxidation of the iron. The bulk density of the residual metal exceeded 75 pounds per cubic foot. In an attempt to lower the quantity of contaminants in the residual metal, another test was designed using automobile hulks which had been prepared by ripping, a low-cost method of scrap fragmentation. Before oxidizing the ripped scrap approximately 62 percent of the total copper was removed in a tumbling, screening, magnetic separation and hand-sorting system. Cast iron made from the residual metal obtained by selective oxidation contained 0.15 percent copper; iron oxide scale obtained from the kiln averaged 0.13 percent copper. Pellets made from the scale demonstrated compressive strengths necessary for blast furnace reduction; lead and zinc were removed by volatilization when the induration was performed in a reducing atmosphere.

Jan 1, 1972

By David Melgaard

A significant emerging recycling, waste minimization problem stems from legacy waste from the nuclear weapons program and from production of power using nuclear fuel. Premium quality metals used in nuclear plants become contaminated, making them unsuitable for reuse. Consequently, decontamination studies were conducted to evaluate the decontamination capacity and partitioning effeetiveness of Electroslag Remelting (ESR). Eight laboratory melts were conducted to evaluate the efficacy of using ESR to transport radionuclides from the liquid metal phase to the liquid flux or slag phase. To determine the decontamination effectiveness, several surrogate compounds for uranium, plutonium and other fission products were added to the melts. During the melts, the melting rate was varied, typical slag additives were used, and two different slag compositions were evaluated. The resultant post-test ingots and slag were then analyzed to determine the partitioning of the surrogates. ESR generally proved very effective in removing contaminates from the metal with a few noted exceptions. -

Jan 1, 2003

By A Trench, S Ulrich, S Hagemann

A synthesis of reported All-In Sustaining Costs (AISC) for 57 Australian gold mines in the period 2014–2016 reveals for the first time the clear influence of grade upon cost performance, most evident in gold-only underground mines. Past syntheses of costs on a single quarter basis have viewed grade as potentially subordinate to other factors such as production scale, mine geometry, mineralisation style and a combination of other mining-related costs. Better understanding of the grade to cost relationship on both an individual mine and whole-of-portfolio portfolio basis is needed. Insight into the roles and trade-offs between other cost-determining factors will aid the future sustainability of the gold mining sector in Australia and assist in targeting prospects for future resource growth and development. While the overall trend is toward higher-grade mines displaying lower costs and vice versa, the grade to cost functions appear radically different between mines based on time-series data. The median cost of Australian gold production in the final quarter of 2016 was A$1081/oz. The threshold for lowest cost quartile production was A$965/oz. Underground production now dominates Australian gold output – with 71 per cent of ounces originating from operations that are either entirely underground or hybrid pit/underground mines. Scale economies are evident, with smaller mines predominately among the higher cost producers. For mines of equal grade, open pit mines are lower cost than underground operations. Reserves are modest, with a median mine life for underground operations of 4.7 years based on current production rates. Reserve additions at mines are likely constrained not only by the finite nature of mineralisation at each mine but also by the geometrical difficulty of accessing suitable drilling locations to test for reserve extensions.CITATION:Ulrich, S, Trench, A and Hagemann, S, 2017. Towards an understanding of production costs at Australia’s underground gold mines, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 241–250 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By M. S. Badollet

INTRODUCTION THE DEMAND for general knowledge on asbestos fibres has increased considerably in recent years. A few publications have printed data showing some of the physical and chemical prupertie3 of asbestos, but in many cases this information is difficult to find and is seldom available when needed. During the past ten years, Johns-Manville have received many inquiries on the physical and chemical properties of asbestos fibres. Fortunately, we had some of the information in our files, and we willingly supplied the data. To help relieve this need, we have tried to present briefly in this paper some of the interesting and out-standing properties of asbestos. This information was obtained over a period of years by search of the literature and by experimental investigations. PROPERTIES OF ASBESTOS FIBRES Table I (1, 2) presents, in convenient form for easy comparison, data on the principal properties of the several varieties of commercial 'asbestos' -actinolite, amosite, anthophyllite, chrysotile, crocidolite, and tremolite. Under each variety of fibre is a brief statement describing the properties in terms of structure, mineral association, origin, etc. Some of the more important data in Table I are expanded and presented in Table II (3). SOLUBILITY OF ASBESTOS A report ( 4, 5) discussing the effects of acids and caustic on asbestos fibres was published in Germany in 1927.

Jan 1, 1951

In spite of advances in measurement techniques and an explosive increase in the volume of research, our understanding of human strength remains in its introductory stages. It is clear that muscle strength is a highly complex and variable function that depends on a large number of factors. It is not surprising, therefore, that large differences in strength exist not only between individuals, but even within the same individual tested repeatedly on a given piece of equipment. The issue is compounded by the fact that correlations of strength among different muscle groups in the same individual are generally low, and tests of isometric strength do not necessarily reflect the strength an individual might exhibit in a dynamic test. As a result of these and other influences, great care needs to be exercised in designing, evaluating, reporting, and interpreting muscular strength assessments. Traditionally, tests of muscular strength were in the domain of the orthopaedist, physical therapist, and exercise physiologist. Such tests are also an important tool for the ergonomist, however, because of the high strength demands on workers in manual materials-handling tasks. In some cases, task demands may approach or even exceed the strength that an individual is voluntarily willing to exert in a test of strength. In such cases, evidence suggests that the likelihood of injury is significantly greater than when the task demands lie well within an individual's strength capacity. Because the relationship among strength capabilities, job demands, and musculoskeletal injury has been established, it is apparent that tests of muscular strength may benefit the ergonomist both in designing jobs and in ensuring that individuals have sufficient strength to safely perform physically demanding jobs. Several strength assessment techniques have been employed for these purposes, each possessing unique characteristics and applicability to job design and worker selection procedures. Our main purpose has been to elucidate these strengths and weaknesses, so that tests of strength may be properly applied in designing jobs and selecting workers. One of the crucial points we have emphasized is that any test of strength used in job design or worker selection must be directly related to the demands of the job.(1) For example, if an occupational lifting task has a high dynamic component, a test of isometric strength is not likely to provide the data necessary for proper design of the job. Of course, dynamic strength tests would also be misapplied in assessing a job requiring isometric exertions. Another potential pitfall is using tests of strength on isolated muscle groups and assuming that they are indicative of whole-body strength. For example, one might mistakenly assume that dynamic trunk extension strength represents a person's capability to perform a lifting task. However, an individual's lifting capacity may be entirely unrelated to trunk extension strength. It may, instead, be limited by an individual's arm or leg strength, depending on the task being performed. A final point on strength assessment should be made. An individual's strength capability cannot be considered a fixed human attribute. Strength training regimens can increase an individual's strength capability by 30%-40%. Whether

Jan 1, 1998

By P. F. Sands

This U.S. Bureau of Mines report reviews the state of the art in blind pneumatic stowing of backfill in voids in abandoned coal mines. It contains a short history of the development of pneumatic equipment in mining and four recent case histories of blind pneumatic stowing. Limitations of pneumatic stowing in terms of equipment wear, costs, backfill material, and methodology are discussed, and some new procedures and designs are reviewed. A bibliography covering pneumatics in mining is included also. This report provides background for the preparation of a Bureau test program in which the variables affecting the efficiency of pneumatic backfilling will be studied using a full-scale surface test facility.

Jan 1, 1990

By W. W. Adams

[The quantity of explosives sold in the United States in January, 1931, for domestic consumption, amounted to 368,100 kegs (9,202,510 pounds) of black blasting powder, 4,810;000 pounds of permissible explosives, and 16,533,000 pounds of high explosives other than permissible. These figures are based on reports received by the United States Bureau of Mines, Department of Commerce, from nearly all manufacturing companies, and include an estimate of sues by several companies that do not furnish monthly reports. Reports actually received from manufacturers shored sales of 365,977 kegs of black blasting powder (consisting of 220,892 kegs of granular powder and 145,085 kegs of pellet powder), 4,687,900 pounds of permissible explosives, and 15,498,152 pounds of high explosives other than permissible. Sales in January, 1931, were smaller than in January last year, the decreases being 14 per cent for black blasting powder, 19 per cent for permissible, and 17 per cent for high explosives other than permissible. Sales in January 1931 when compared with soles in December 1930, show increases for all three classes of explosives as follows: 2 per cent for block blasting powder, 16 per cent for permissible explosives, and 7 per cent for other high explosives. PERMISSIBLE EXPLOSIVES: Of the 4,687,900 hounds of permissible reported sold during January, 97 per cent was used for coal-mining operations, Including 32 per cent for anthracite mines and 65 per cent for bituminous mines. The following Staten were the largest users of permissible explosives daring January: Pennsylvania, West Virginia, Illinois, Alabama, Kentucky, Indiana, and Utah. Their combined sales represented 89 per cent of the entire sales reported for this class of explosives.]

Jan 1, 1931

By Charles H. Bucknam

A gold sampling optimization study was carried out in support of open pit gold mining operations for the Newmont Gold Company Bootstrap-Capstone deposits in Northeastern Nevada. Six bulk samples were tested using fire refining techniques at field particle size, to determine coarse particle heterogeneity of the ores, and by gravity .concentration methods at 10 mesh particle size, to observe any particulate gold liberation. An overall sampling model is presented for the deposit based on the pooled test information, to reconcile the results of coarse particle heterogeneity testing and the fine particle 'liberation testing. The sampling model is used to recommend procedures to control the variability of gold grade estimation due to the fundamental error (nugget effect) during sampling, sample preparation and assaying of the ores and other fundamental variances. The technique of simplified quantitative risk analysis (SQRA) is used to provide an economic justification for implementation of. recommended improvements to field sampling practices.

Jan 1, 1999

By C. West

Structured or embossed HDPE and LLDPE geomembranes have been available to mine owners and designers for over ten (10) years. As many owners and designers discover and demand the consistent high quality characteristics of this type of geomembrane due to the unique manufacturing process, the use of these materials in new mines, mine expansions and final closure designs has steadily increased. Structured liner materials are available for double lined and final cover systems and are revolutionizing the way ponds, pads and final closures are constructed. This paper will discuss the structured or embossed geomembrane concept and manufacturing process. Additionally, the paper will present comparative testing illustrating the major advantages of using this type of product in these types of applications. Both technical and economic advantages are illustrated. The cost savings include lower installation costs, less material used, and third party inspection times not to mention better performance. These new systems will be presented.

Jan 1, 2011

By W. J. Wright

Summary This paper describes the general situation of the mining industry in New Brunswick, and gives a detailed description of the recent developments in the antimony deposits at Lake George and the copper deposits in the vicinity of New Horton. At the end are lists of the most interesting geological literature relating to the Province and of the geological and topographic maps that have been published. Introduction In presenting this paper to the Institute, I apologize for the small amount of scientific data which it contains. Recent investigations in the Province of New Brunswick have been carried on largely by outside interests, and at present we ourselves are in the position .of taking stock. However, I am glad of the opportunity of giving you a general idea of the situation. The Province is making an honest effort to learn the truth concerning her mineral deposits and in time hopes to collect data which should be of interest to the mining community.

Jan 1, 1931

By Wesley Holmes

Concentrating, nodulizing, and smelting studies were conducted at the Albany Metallurgy Research Center of the Bureau of Mines to determine whether (1) western iron ores of the type found in the Carter Greek deposit near Dillon, Mont., could be utilized; (2) concentrates of acceptable grade with good iron recovery could be attained by wet-magnetic beneficiation; (3) nodulized concentrates could be smelted with reductants readily available in Montana; (4) iron concentrates could be smelted without prior agglomeration; and (5) high-purity iron could be produced directly from high-grade concentrates, Three small samples and two tonnage samples from the Carter Creek deposit were uniform in chemical composition, and their iron content averaged about 31 percent. They were found to be banded gneisses, and magnetite was the principal iron-bearing mineral.

Jan 1, 1962

By P. G. Kovalchik

Safe electrical operation of shuttle cars depends upon maintaining the trailing cable's conductor temperature below 90° C. However, trailing cables are wound on and off reels, which changes the heat transfer characteristics of the cable-reel system. Derating factors for trailing cables are an attempt to adjust for this changing heat transfer mechanism in a practical way. The U.S. Bureau of Mines conducted research to determine acceptable derating factors for reeled mine trailing cables, using four cable-reel combinations, representative of industry usage. Cables were continuously and intermittently loaded at different duty cycles with direct currents of different magnitudes. Relationships between the average temperature rise and current load were established for each layer of each cable. Two models were constructed; one used empirical data from the continuous and intermittent load tests, and the other was based on thermodynamic theory. Results obtained from the theoretical model were compared with those from the empirical model for the rated temperature rise of the cable. Both models can be used to simulate a variety of test conditions including those that normally cannot be conducted in the laboratory. This information was used to determine acceptable derating factors for each layer of these cable-reel combinations.

Jan 1, 1994

By Simons W.

The object of the paper is to describe the standards of quality that should be specified in ordering material ordinarily required for colliery use, and also the qualities most suitable for particular purposes. Tables are presented of British Standard tests for wrought iron grades A, B and C, Admiralty tests for iron in chain, the quality of material for wheels and axles, and the composition and mechanical properties of wrought iron, Armco (ingot) iron and drawbar-gear steel. (Paper presented at the North Staffordshire Institute of Mining and Mechanical Engineers' general meeting held in Stoke-on-Trent, March 27th 1916, Mr. John Gregory, President, in the chair)

Dec 1, 1916