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By Raymond E. Davis

LET'S imagine we are at the Grand L Coulee Dam, where daily 15,000 barrels of low-heat Portland cement and 27,000 tons of processed aggregate in various sizes are mixed to produce 30,000 tons of concrete. Inspect the autographic records which show for each 4-cu-yd. mixer batch of concrete the weights of its constituent materials including its several sizes of aggregate, cement, and water, and which also show the period of mixing and the consistency of the mix. Watch the inspectors sample and test the aggregate for gradation and moisture content of sand, and sample the concrete for homogeneity. Watch the huge buckets deposit the concrete in the forms. It looks too dry to handle, but the concrete vibrators make it melt away. Just enough vibration fully to com- pact the mass, but not enough to produce segregation of the materials; the inspector says when. See the sprinkler system covering all hardening concrete with a spray so that it may not thirst for water. Watch the cleaning of the top of an old lift preparatory to placing a new lift; the sand blasting; the blow-down; the mop-up; the minute inspection.

Jan 1, 1939

By H. Tveit, E. H. Myrhaug, J. K. Tuset

Silicon metal as a commodity material is produced by carbothermic reduction of quartz in electric submerged arc furnaces, where CO2 forms as a by-product. Since 1997 the Norwegian Ferroalloy Producers Association have been engaged in research programmes aiming for reduced CO2-emissions associated with fossil carbon in their processes. One important issue has been to study how charcoal and wood chips perform compared to coal and coke in the silicon process. The ability of the carbon-rich reduction materials to react with SiO-gas is commonly assumed to be of large importance to the performance of the process. Based on laboratory experiments with different carbon materials, combined with estimation of parameters in a mathematical model of the reaction between carbon and SiO-gas, a foundation for a theoretical study of the performance of the carbon materials in a silicon furnace is established.

Jan 1, 2004

By J. B. Gayle

In a modern blast furnace, production depends, to a large extent, on the rate at which the furnace gases can be forced through the charge. Since these gases must make their way through the voids between particles of coke, ore, and limestone, the size and size distribution of the stock-column materials are of considerable importance. Also, because the coke pieces support the weight of the overburden and provide the majority of the voids through which the gases pass, their ability to withstand the shattering and abrading forces to which they are subjected should be related to the maximum obtainable production for any particular furnace. Although the wide acceptance of this point of view is indicated by the ever-increasing demand for stronger and more uniform blast-furnace cokes, economic considerations demand that a quantitative evaluation of the relation between coke quality and blast-furnace performance be made available to the industry at the earliest possible date. The following studies of size-distribution patterns and breakage processes were, therefore, conducted as a part of a preliminary investigation intended as a basis for future studies of the relation between coke quality and blast-furnace performance. The major findings may be summarized as follows: 1. New evidence for the presence of two independent distributions of sizes in run-of-oven cokes has been obtained, and a method for characterizing and estimating the relative importance of the individual distributions has been demonstrated. This method has also been used to study the different types of degradation taking place during the tumbler test.

Jan 1, 1954

By Lori Kormos, Jhonny Carrión De la Cruz, Dominic Fragomeni, Elizabeth Whiteman, Jorge Oliveira

"Process diagnosis, flowsheet design and optimisation are most effectively and efficiently achieved through the use of metallurgical testwork combined with more modern quantitative mineralogical techniques. Integration of the mineralogical data in testwork programs provides a resolution that cannot be obtained from assays alone and can direct the flow of work to result in optimized conditions more quickly than would otherwise be possible. At Xstrata Process Support (XPS), QEMSCAN (Quantitative Evaluation of Materials by Scanning Electron Microscope) and EPMA (Electron Probe Micro Analyser) information can be employed to diagnose specific issues in a plant or lab scale test and are routinely combined with other metallurgical data sets to benchmark performance, design and optimise flowsheets. Representative sampling protocols for ore bodies or test products, the use of geometallurgical unit classification and high confidence metallurgical test programs are key components of the strategy. Two case studies from Xstrata Zinc’s Antamina Mine and Concentrator in Perú, and Xstrata Nickel’s Nickel Rim South Mine in Sudbury are described to show how the use of quantitative mineralogy were used to diagnose a plant issue and how the data can be integrated into metallurgical programs to assist mineral processing engineers to design and optimise flowsheets.INTRODUCTIONOver the past decade, there has been a shift away from metallurgical testing that employs only chemical assays to quantify performance; the use of empirical observation in order to optimise a flowsheet; and the extraction of bulk samples for testing or piloting. The integration of geological information into the planning and execution of testwork programs including the use of quantitative mineralogy has improved the overall quality and predictability of metallurgical programs. At the same time, improvements to metallurgical testwork protocols such as rigorous statistical assessment of results, the use of factorially designed experimental strategies (DOE), and replicate flotation with appropriate quality controls, has improved the confidence level in these results.Process diagnosis, which utilizes quantitative mineralogy, can clearly define the root cause of the metallurgical issue. Whether used on its own to diagnose an issue or in combination with other metallurgical testwork, the use of mineralogical data has become the standard in the mining industry."

Jan 1, 2010

By J. S. Hansen

To advance technology that can conserve critical materials, the Bureau of Mines investigated a cast-on hard-surfacing that wear resistance and confines alloy additions to wear-prone surfaces. Wear-resistant material in form is on a polystyrene , the is embedded in a mold of unbonded s and the wear-resistant material is transferred to a cas surface at the time of For low-stress abrasion, derived from high-carbon ferro-chrome had higher wear resistance than did commercially available weld-hard. The microstructure of the was typi-white iron carbides. Free carbon added to the ferrochrome powder produced more M7C3 carbides than did material contained in surfacings made from ferrochrome alone, and improved the wear resistance. Several white iron powders with greatly reduced chromium contents also white iron contain-M7C3 carbides. One derived from white iron powder had wear resistance to that of weld-deposited hard facings. Among the parameters investigated, surfacing thickness was found to have a or influence on diffusion of elements out of the , microstructure, and wear resistance. The results of field tests on bucket-wheel excavator teeth and plowshares with cast-on hard surfacing are given.

Jan 1, 1985

By Orlando Martino

This regional report covers the mineral industries of Canada and 40 countries and areas in Latin America and the Caribbean Basin. Also included is a brief description of the mineral potential of Antarctica. The Latin American region encompasses an area twice that of the United States. Latin America and Canada have a rich and diversified endowment of mineral fuels, metals, and industrial minerals. Tables 2 and 3 provide a summary view of the importance of Latin America and Canada's output of its major mineral commodities in world mineral supply in 1989 and 1990.

Jan 1, 1993

By Richard E. Thill

Engineering properties of rock are essential in most phases of mining from site reconnaissance through mineral processing. Review of the literature indicates, however, that property data is scarce for most coal measure rocks in the United States. The Bureau of Mines, U.S. Department of the Interior, has undertaken a wide-ranging testing program to provide more complete property data for coal strata in the U.S. coal basins. The property data are expected to have application in geophysical exploration, the development of pre- mining and hazard detection probes and instrumentation, mine design, engineering and rock mass classification, subsidence engineering, and ground control. This paper describes the comprehensive program encompassing in situ geological, geophysical, and geotechnical properties and laboratory determinations of acoustic, electromagnetic, physical, mechanical, and index properties and discusses results for 500 ft of coal measures at a minesite in the Northern Appalachian, Eastern Coal Province.

Jan 1, 1982

By Michael W. Lewis

The latest downturn in the world’s metal prices has forced many mining companies to focus on cost reduction and productivity improvements to remain competitive. Maintenance represents a significant part of the overall operating costs in the mining industry. A structured, proactive maintenance approach, such as reliability-centered maintenance, can achieve cost reductions and productivity improvements. Remote condition-monitoring systems are becoming commonplace because they have the potential to identify problems before failure. Detection of equipment degradation before failure will enable repairs to be scheduled, thereby reducing costs and interruptions to production. The mining industry is in the midst of uncertain times. Decreasing commodity prices, demand, head grade and capital availability along with increasing environmental requirements have put pressure on mining companies to significantly reduce costs to maintain short- and long-term viability. Corporations are looking at expansion, merger/consolidation and financial/hedging programs to achieve these cost reductions. Mines are reducing costs by eliminating all but essential expenditures, increasing production levels, reducing overtime and investing in new technologies.

Jan 1, 2000

By Borje Bjorkvall

At LKAB's plants in Lappland, Sweden, sintered pellets are manu-factured according to three different industrial processes, viz. shaft furnace at Malmberget, straight-grate at Kiruna and grate-kiln at Svappavaara. At present the total annual capacity amounts to 4.7 million tons. However, since it has been decided to erect a new straight-grate plant (2.5 million tons) at Malmberget, and because of the decision to extend and rebuild the existing plants, it is estimated that the annual capacity will be increased to somewhat over 8 million tons by 1973. The great majority of the pellets produced is exported. They are thus reloaded several times and generally speaking roughly handled, resulting in larger or smaller product losses on arrival at the point of use. It is there-fore of great economical interest to have a good control over the transport strength of the pellets by appropriate quality testing at the point of production. In addition to good transport strength, further demands are ob-viously made on pellets destined for blast furnace operation. The blast furnace burden must maintain a good permeability for the gas. The pellets must thus have a favourable size distribution and must not be so weakened by reduction that they disintegrate under the stresses and clog the blast furnace shaft. Furthermore, the burden must have good reducibility. An increase of the rate of reduction can obviously mean increased blast furnace capacity and reduced coke consumption. In order to optimise the properties of the pellets in these respects, the producer must also be thoroughly familiar with their behaviour during reduction, particularly as the customer's interest in the reduction properties of the pellets' has increased over the last few years. Up to now the only quality demands the customer has made have generally had to do with the cold strength and the screen analysis. Thus a quality control of in addition to good transport strength, further demands are obviously made on pellets destined for blast furnace operation. The blast furnace burden must maintain a good permeability for the gas. The pellets must thus have a favourable size distribution and must not be so weakened by reduction that they disintegrate under the stresses and clog the blast furnace shaft. Furthermore, the burden must have good reducibility. An increase of the rate of reduction can obviously mean increased blast furnace capacity and reduced coke consumption. In order to optimise the properties of the pellets in these respects, the producer must also be thoroughly familiar with their behaviour during reduction, particularly as the customer's interest in the reduction properties of the pellets' has increased over the last few years. Up to now the only quality demands the customer has made have generally had to do with the cold strength and the screen analysis. Thus a quality control of

Jan 1, 1972

MR. Woo's succinct description of the mining and smelting of silver-lead in Mongolia, with the roasting-and-reduction process and cupellation, has much interest as a picture of methods that not only may have been in use, as he suggests, a thousand years ago, long before the existence of mining schools or chemical laboratories, but probably vary little, if at all, from the practice of prehistoric times, when King Priam's handsome silver vases, cups and bowls were formed. For it is highly improbable that such large objects were made from comparatively rare native silver, and the metal must have been smelted from ore, and most likely in great part from galena,, with cupellation of the lead. Dr. W. A. P. Martin, in his excellent book on the Lore of Cathay, points out that Chinese alchemy is over 2000 years old, antedating the European by at least six centuries; and he infers that the Chinese skill in metallurgy and many branches of practical chemistry owes its origin to " those early devotees of the experimental philosophy who passed their lives among the fumes of the alembic." Those alchemists, however, may have more likely derived some of their leading ideas from the mys terious, and at that time wholly unexplainable results observed in already very ancient metallurgical processes; in which, for example, certain stones were transmuted, as it were, into metals widely divergent in character from their ores, and even silver and gold were obtained from the most unlikely-looking mate rials. It is therefore, in any case, not improbable that the Chinese may have preceded western nations in the discovery of metallurgical methods. At all events, it is now evident that the Japanese acquired these arts from China, the former source of all their higher civilization. My own observation of old-fashioned silver-smelt ing at Hosokura, on the main island of Japan, and about 220

Jan 1, 1903

By Jörn M. Seitz

Dynamic load testing is employed with ever increasing frequency to estimate the strength and elastic settlement behavior of piles of all types. For dynamic loading ram masses up to 20 Mg have been used and pile resistance forces up to 30 MN have been activated. Strains and accelerations induced by the impact are measured near the pile top and a load-set curve is computed by the so-called CAPWAP method. This paper briefly describes both the necessary equipment and other details of the dynamic tests and the available analytical tools for data interpretation. Furthermore the need for further research and the current status of standardization will be discussed. This paper also presents the results from several static and dynamic correlation tests on cast-in-situ piles of up to 2 m diameter and 64 m length. The results demonstrate the economical and technical feasibility of this test method.

Jan 1, 1987

By Paul J. Sylvester, Yeonuk Choi, Mike Nelson, Louis J. Cabri, Mike Tubrett

"The development and characterization of sulphide standards containing as many as seven precious metals has increased the efficiency and comprehensiveness of micro-analyses for deportment studies using laser ablation microprobe inductively coupled plasma mass spectrometry (LAM-ICPMS). Because trace precious metals occurring in solid solution or as sub-micron inclusions in sulphides, arsenides, and sulpharsenides are often heterogeneously distributed, a significantly large number of analyses are required. Using well-prepared samples it is possible for up to 120 analyses per day, far more than by other comparable methods. Examples will be discussed from projects focused on the deportment of Au and the platinum group elements (PGE).INTRODUCTIONBecause gold and the platinum-group elements (PGE) occur as both discrete minerals and in trace quantities in a variety of minerals (mostly sulphide, arsenide, and sulpharsenide minerals), specialized trace analytical methods were developed and applied to determine the deportment of precious metals in ore deposits, requiring sensitivities ranging originally from about hundreds to presently tens of ppb for individual precious metal or less.In mineralogical studies, micro-analytical techniques such as the electron microprobe were first applied to obtain analyses for major elements in about 1959-60, but as the instrumentation improved early attempts for PGE in potential carrier minerals indicated that reasonable levels of detection (LOD) were of the order of 300-400 ppm, depending on analytical conditions, X-ray spectral lines, and mineral matrix (e.g., Cabri and Laflamme, 1976). Eventually, the lowest detection levels by electron probe micro-analyses (EPMA) obtained for some PGE were of the order of 10s of ppm using high accelerating voltage and current for extended measuring time on peak and background (Gervilla, Cabri, Kojonen, Oberthür, Weiser, Johanson, Sie, Campbell, Teesdale and Laflamme, 2004)."

Jan 1, 2010

By W. M. Pytel

The applicability of the beam theory in analysis of roof- pillar-weak floor interaction in partial extraction room-and-pillar mining is presented. The mine structure is modeled as an equivalent multi-indeterminate overburden elastic beam supported by elasto-plastic pillars; resting on a viscoelastic layer of immediate weak floor strata underlain by a competent rock mass. The developed analytical model was initially utilized to conduct sensitivity analyses of different variables affecting the mining system, such as the deformability of coal and weak floor strata, thickness of weak floor strata, number of pillars in a panel, width of pillars, width of panel etc. These analyses were then extended to three overburden strata - coal pillar - floor strata lithologies typical of active coal mining areas in Illinois.

Jan 1, 1989

By H. Reimer

The rates of return on investment are examined for several major Canadian mining companies. Because we are dealing with a highly cyclical industry, subjected to widely fluctuating metal prices, rates of return are examined over a 20-year period. Conveniently, the first decade examined reflects the period when the industry enjoyed incentives to develop deposits; during the second decade, incentives were reduced and the industry became the most heavily taxed industry in Canada. The high rates of inflation since 1973 have distorted the real rates of return on investment if one considers replacement cost.

Jan 1, 1977

By Yoginder P. Chugh

Subsidence may be observed above partial extraction shallow room-and-pillar mines where the coal seam(s) is associated with weak and thick claystone in the floor. This paper presents results of subsidence studies at such a mine. During the 26-month study period, a time dependent subsidence causing a maximum vertical movement of 50 mn was observed. After a subsidence rate of 6.0-6.5 m/month for the first two months after development of mine workings, the rate decreased to 0.8-0.9 mm/month after 17 months. However, presumably due to settlement of barrier pillars, it increased therafter to 1.7 mm/month for the next 9 months. Angle of draw, based on zero subsidence, was calculated to be about 29 degrees. Maximum tensile strain and compressive strain values observed were 0.040 pct and 0.039 pct respectively. A hypothesis was fomlated to correlate surface subsidence movements with observed underground movments. The data collected to date fits reasonably well within the formulated hypothesis.

Jan 1, 1989

By Corby G. Anderson

Since 1985, the Sunshine Mining Company has used a patented nitric-sulfuric acid pressure leaching system for production of silver and copper from a refractory sulfide ore body. To better understand this novel process, a program of lab scale testing was undertaken to quantify the effect of system variables on silver recovery. Some of the factors studied include temperature, agitation, acidity, vessel pressure, particle size, percent solids and oxidizer amount. In turn, this knowledge will be applied in actual plant practice to upgrade reaction time, increase concentrate throughput, raise silver recovery and lower reagent costs. A discussion of plant process changes resulting from lab scale testing is included.

Jan 1, 1991

Our mission is help ensure our country has an adequate, dependable supply of minerals and mate al to meet its national security and economic needs at acceptable social, environmental, and economi[c] costs. We do this by promoting and encouraging private enterprise in the development of viable and stable mineral industries through the transfer of innovative extraction, processing, recycling, an environmental technologies; our use of cooperative partnerships with industry, academia, an government; our timely, authoritative worldwide mineral intelligence; our advocacy of public policies based on good science and sound economics.

Jan 1, 1994

By P. N. Anyalebechi

A comparative study of the mechanical properties of automotive steering knuckles produced by three different shape-casting related processes has been conducted. It involved the characterization of the tensile and fatigue properties of aluminum alloy A356 knuckles produced by the vacuum/pressure riserless casting (VRC/PRC), pressure counter pressure casting (PCPC), and the hybrid Cobapress (a casting-forging) processes, in accordance with the appropriate ASTM standards. Surprisingly, the knuckles produced by the hybrid Cobapress process exhibited the lowest strength. For example, the average 0.2% yield strength of the Cobapress knuckles was 31 MPa and 40 MPa less than that of the VRC/PRC and PCPC knuckles, respectively. However, between stresses of 150-200 MPa, the fatigue lives of the VRC/PRC, PCPC, and Cobapress knuckles were comparable. But above 200 MPa, the Cobapress knuckles exhibited the lowest fatigue life. The observed differences in the mechanical properties are attributed to the inherently different microstructures of the different knuckles.

Jan 1, 2009

By R. Hardy

LaModel is a boundary-element program capable of calculating the displacements and stresses in thin bedded deposits such as coal, salt, or potash. Throughout its history, it has continually been upgraded in order to expand analysis detail and stay current with the latest advances in computer technology. The most recent enhancements include: an increased grid size capability, a significant increase in the speed of the automatic grid generation using an AutoCAD visual interface, implementation of subsidence-based horizontal strain calculations for multiple-seam situations, and pillar safety factor calculations. To demonstrate these new features, a multiple-seam case study of a longwall panel undermining an active set of main entries is presented.

Jan 1, 2006

By Nicholas J. Grant

It is the purpose of this paper to examine a number of the recent developments in powder metallurgy, being most concerned with those which are yet to prove themselves rather than those which have achieved commercial maturity. Such developments include the production of very much coarser and very much finer powders, down to the near-micron size range. Also considered are activated sintering, direct powder rolling and extrusion (both hot and cold), brazing and welding, hydrides of reactive metals, oxide dispersion strengthened alloys and theoretical evaluations. Introduction T HERE surely can't be very much argument with the fact that powder metallurgy has made large advances on many fronts during the past ten or more years (1). These advances have taken place in raw materials, in processing, in product development and in a better understanding of many of the phenomena which occur in the various steps involved in powder metallurgy. It should be clear, in view of such growth, that it will not be possible to highlight all of the new developments in the present paper. Many of these developments,

Jan 1, 1965