Search Documents

By V. J. Hucka

A 0.5 m (20 in) diameter high pressure natural gas pipeline crosses over a coal mine located in Central Utah. Ground movement induced by the mining operation could possibly place excessive strain on the pipeline causing it to rupture. The mining operation extracts coal from two seams using the room and pillar method. The seams are situated one on top of the other and both lie directly under the pipeline. At present, only the upper seam is being mined beneath the pipeline. However, in the future, the mining operation of the lower seam will also affect the pipeline. As would be expected, mining of both coal seams causes surface subsidence. This is especially true when the pillars are extracted during retreat.

Jan 1, 1983

By J. L. Boyd

The mining and processing of basic metals relies on water as a medium for transport. Metallurgical ores are ground, concentrated, leached and refined in an aqueous medium. Water is used for temperature control during processing and in air pollution abatement during smelting. All of these process steps result in liquid wastes. Many of the aqueous wastes from ore processing areas become the raw product for a second stage and water recycling may begin. The point at which water recycling or reuse has been initiated in the past, rather than water discharge, was where water conservation was manditory due to a shortage, where process conditions would allow or benefit from reuse, and where economic considerations demanded reuse. The Fontana, California plant of Kaiser Steel Corporation is an example of an integrated steel plant that was forced to practice water conservation and reuse due to its location in an arid environment.1 Only a small amount of water required to maintain the water reuse system in balance with respect to dissolved solids and product quality is discharged. The Butte, Montana copper ore processing plant of The Anaconda Company obtains 66% of the water required for production by recycling, after clarification and chemical treatment, 30 MGD of wastewater from its tailings ponds. This operation is estimated to save the company about $1200/day over a once through water system.2 Here plant location and economics favored water reuse.

Jan 1, 1975

By K. H. McDaniel

Eight Mine Weather Stations (MWS) installed at the Waste Isolation Pilot Plant (WIPP) to monitor the underground ventilation system me helping to simulate real-time ventilation scenarios. Seasonal weather extremes can result in variations of Natural Ventilation Pressure (NVP) which can significantly affect the ventilation system. The eight MWS(s) (which previously collected and stored temperature, barometric pressure and relative humidity data for subsequent NVP calculations) were upgraded to provide continuous real-time data to the site wide Central Monitoring System. This data can now be utilized by the ventilation engineer to create real-time ventilation simulations and trends which assist in the prediction and mitigation of NVP and psychrometric related events.

Jan 1, 1997

By William F. Abercrombie

The role of the laboratory is described in relation to the prospecting and exploration of kaolin clays. Test methods used to evaluate crude ore samples of kaolin clay for commercial consideration are reviewed. A background of the kaolin mineral and known means of prospecting this mineral are presented. Common analytical methods are discussed with special emphasis on those in use today.

Jan 1, 1982

By J. B. Pateiro Fernandez, S. Möllerherm, E. Drüppel

"Since 1997 the Institute of Mining Engineering 1 at the Aachen University is dealing with the concept of sustainable development in the mineral industries. During this time it has conducted several research projects in this field. Its latest project is on the development of sustainability indicators for the German mineral industry. This paper describes some results of this project. A process chain analyses have been carried out identifying economic, social and environmental effects of the minerals extraction. Thirty indicators reflecting the particular conditions in the mineral industry have been designed. One important challenge was the design of quantifiable indicators taking into account the life cycle of a mining operation as well as mineral beneficiation and enrichment of the raw material."

Jan 1, 2005

By W. S. Sanner

Experiments were conducted to determine the quantity and purity of ultraclean anthracite that could be prepared in the laboratory, using conventional separating techniques. A low-, a medium-, and a high-volatile anthracite were studied. Specific gravity separation followed by grinding, screening, and refloating at lighter specific gravities yielded small quantities of material purified to 1.0 percent ash, as follows: From low-volatile anthracite, 0.7 percent; from medium-volatile coal, 1.0 percent; and from high-volatile coal, 2.3 percent. The reduction in ash had no appreciable effect on the volatile matter or sulfur content of the coal. The limited quantities of material containing 1.0 percent or less ash obtainable indicate that if ultraclean coal is desired, a practical approach should include the processing units as an integral part of a conventional dense-media washing plant.

Jan 1, 1968

By S. M. Khandrika

Most of the coal presently used by the utility industry is cleaned at preparation plants employing wet processes. While water is the mainstay of coal washing, it is one of the least desirable components in the final product causing a reduction of the heating value as well as handling difficulties. Currently available dewatering techniques are inefficient for dewatering very fine coal (minus 325 mesh). The US coal industry has expressed serious concern about utilizing advanced cleaning processes such as column flotation because an efficient and economical dewatering process is not available.

Jan 1, 1992

Water contact angles in the air/water/francolite, fuel oil/water/francolite and fuel oil/water/quartz systems were measured to describe the wetting characteristics of these minerals. It was found that white francolite is more hydrophilic than black and tan francolite both in the absence and presence of fatty acid addition. The contact angle measurement results do not correlate very well with the flotation response and it appears that kinetic aspects of the bubble attachment process play an important role in the francolite-fatty acid flotation system.

Jan 1, 1997

By J. W. Shield

Refractory sulfide flotation or gravity gold concentrates are coated onto a sized support matrix and placed in a heap configuration for biooxidation. The surface coating is typically less than 0.05 in. thick and the support matrix is preferably composed of 0.375 to 0.75 in. diameter material. The exposed thin coating of sulfides reduces biooxidation rate limitations due to oxygen mass transfer. The large spaces between matrix particles reduce resistance to fluid percolation and aeration in the heap. The capital and operating costs for this biooxidation configuration are significantly less than for concentrate biooxidation in stirred tanks. After 30 to 90 days of biooxidation, sub- sequent gold recoveries exceed those seen in whole ore heap biooxidation and are comparable to recoveries obtained from stirred tank biooxidation processes. Results from laboratory and pilot testing indicate that this technology is a viable alternative for pretreating sulfide refractory gold ores.

Jan 1, 1997

By K. C. Corin, B. McFadzean, J. G. Wiese

The Bushveld Complex of South Africa contains almost 90% of the world’s reserves of platinum group minerals (PGMs). In the flotation of PGMs, there are significant challenges arising from the need to treat ever-decreasing grades of the relevant ore deposits. The major challenge in the flotation of these ore bodies is the control and management of the gangue minerals, particularly silicates such as orthopyroxene and plagioclase feldspar which are often rimmed with talc which makes them naturally floatable. It has been shown that various polysaccharide depressants such as CMC and guar have different properties in terms of depressing the gangue minerals. Since the PGMs are often associated with sulphides, copper sulphate is widely used as an activator in PGM flotation but can inadvertently activate the gangue minerals and reduce the recovery of PtTe2 which accounts for up to 40% of the Pt in the Platreef ore body. Depressants also reduce the mass of solids reporting to the froth and can thus destabilize the froth. This effect on the froth can be mitigated by using higher frother dosages or water of higher ionic strength. In summary due care needs to be taken to carry out site test work to develop an optimum ratio of collector, frother, activator and depressant to ensure that the highest grades and recoveries of the PGEs are obtained while reducing depressant dosage as much as possible. Chromite recoveries can be reduced through the application of gravity separation or reducing entrainment through reduced water recovery. INTRODUCTION The Bushveld Complex located in the north of South Africa contains the world’s largest deposit of Platinum Group Minerals (PGMs) (1). The so-called upper Critical Zone of the Complex hosts the largest concentration of platinum group elements (PGEs) in the world. The Zone hosts the Upper Group Chromitite No.2 (UG2) reef and Merensky Reef as well as the Platreef mineralization of the northern limb of the Bushveld Complex. The Merensky pegmatoid Zone contains the base metal sulphide grains and associated PGMs. Of particular importance to the topic of this paper is the occurrence in these reefs of various gangue minerals. The Merensky Reef consists predominantly of orthopyroxene (~60%), plagioclase feldspar (~20%), pyroxene (~15%), phlogopite (5%) and occasional olivine. Secondary minerals such as talc, serpentine, chlorite and magnetite have widespread occurrence. Of these, talc is the only mineral to show significant natural floatability (2,3). Although present in small amounts talc is closely associated with pyroxene and imparts significant floatablity to the high concentrations of pyroxene present in these ores (4). The base metal sulphides consist predominantly of pyrrohtite (~40%), pentlandite (~30%) and chalcopyrite (~15%). The major platinum group minerals are cooperite (PtS), braggite [(Pt,Pd)NiS], sperrylite (PtAs2) and PGE alloys. The UG2 consists predominantly of chromite (between 60 – 90% by volume) with lesser silicate minerals (5 – 30% pyroxene and 1 – 10% plagioclase). Other minerals present in minor concentrations, can include silicates, oxides and base metal sulphides. Total PGE varies by locality but on average range between 4 and 7 g/t. The PGMs present in the UG2 Reef are highly variable, but generally the UG2 is characterised by PGE sulphides such as laurite (RuS2), cooperite (PtS) and braggite [(Pt,Pd)NiS. The base metal sulphides consist predominantly of chalcopyrite, pentlandite and pyrrhotite. The Platreef is located in the northern limb of the Bushveld Complex. This reef consists of a complex assemblage of rock types, with pyroxenites, serpentinites and calc-silicates being the most abundant. Base metal mineralization and platinum group element (PGE) concentrations are found to be highly irregular, both in value as well as in distribution. The predominant platinum group minerals (PGM) in the mined area of the Platreef are the PGE tellurides, alloys, arsenides and sulphides. T

Jan 1, 2019

By Brig M. Moudgil

It was reported earlier that francolite and dolomite from the South Florida deposits cannot be selectively floated using conventional conditioning with sodium oleate as the collector. However, dolomite could be separated from francolite if the minerals were first conditioned at pH 10 followed by reconditioning at a lower pH. An optimum separation was achieved at a reconditioning pH below 4.5. Reconditioning pH and collector concentration were determined to exert a major influence on the selectivity. Flotation, adsorption and transmission infrared spectroscopic results are presented to elucidate the mechanisms underlying the observed selectivity.

Jan 1, 1984

By S. Behl

A major limitation in developing successful selective flocculation schemes is the difficulty encountered in adsorbing the polymeric flocculant only on the desired substrate. In this paper a correlation between selectivity of flocculant adsorption and separation efficiency is outlined and a potential technique to achieve selective adsorption of flocculants is discussed.

Jan 1, 1992

By Robert L. Frantz

The various facets of university-company cooperative activities and the opportunities for collaborative research for the mineral industries are presented in this paper. The advantages and disadvantages of various alternative research funding arrangements for the researcher, the university, and the sponsoring corporation are discussed. Examples of university-industry cooperative research programs are briefly outlined. The concept of a cooperative mining research program is presented. The improvement of performance through techno- logical developments and human skills may well be the greatest competitive edge available to the U.S. mining industry. In this regard, the need for new endeavors between industry and universities can hardly be overemphasized.

Jan 1, 1984

By D. D. Eyer

New or improved technology will continue to drive productivity improvements through the next decade. In January 1988, I presented a paper titled, "Large Underground Mines of the 1990s? before the SME. I will follow some of the themes developed in that paper as modified by our experience in the past two years. In order for a coal company to be profitable today, it has had to reduce unit costs experienced in the past. This is because the current average realization, even accounting for a recent strengthening, remains below that of a few years ago. Doing business as was done in the past is not good enough. The coal industry needs to increase productivity in the range of 5-10% annually merely to stay even with rising costs. Underground productivity has been increasing more rapidly than that for surface mining. With the exception of the Powder River basin of Montana and Wyoming, underground productivity has caught up with that for surface mining in many regions of America. There are a number of technological factors which have attributed to increases in underground productivity and which should be factors in the future.

Jan 1, 1990

By R. R. Klimpel

The grinding of coal-water slurries has received increasing industrial attention during the last decade. In particular, there is long-term interest in the use of pulverized coal-water slurries to replace oil in combustion equipment and the development of coal gasification/liquefaction processes which require coal-water slurries as feed. More specifically, the use of coal-water slurries in gasification requires grinding a high density slurry containing the smallest amount of water consistent with slurry pumping and spraying. As part of a fundamental engineering research support program aimed at the industrial implementation of dense coal-water slurry grinding, this author has published several papers on how specific rates of breakage vary as a function of slurry rheology, Klimpel (1982, 1982/83). These papers demonstrated that there is a consistent pattern of change in specific rates of breakage of coal in dense slurries with controlled variations in slurry rheology. By matching rheological data with laboratory grinding results, it was possible to identify directly slurry conditions that correspond to: (1) slowing down of breakage rates, (2) the occasional acceleration of breakage of some sizes, and (3) conditions where chemical additives will increase rates of breakage.

Jan 1, 1990

By Yiming Sun, David Tsztoo, Rick Nolting, Adam M. Wirthlin, Rebecca Fusee

"Excavation and initial support of the New Irvington Tunnel presented significant challenges, including rapidly changing ground conditions, heavy ground loads, and squeezing. Such behaviors were anticipated from historic tunneling records of the adjacent Existing Irvington Tunnel, and extensive site investigation, but clearer understanding of their actual extent and causes has resulted from convergence measurements, observations of ground behavior, initial support monitoring and detailed geologic mapping. Time-dependent movements, documented hours to months after excavation in clay-rich rock and in moderately to intensely fractured rock, identified squeezing areas, allowed classification by currently-used predictive methods and added to the list of lessons learned in tunneling such ground. INTRODUCTION In March 2003 the San Francisco Public Utilities Commission (SFPUC) authorized funding for the $4.6 billion Water System Improvement Program (WSIP) to repair, replace, and seismically upgrade its water system. The program consists of 35 local projects located within San Francisco and 48 regional projects located in several counties from the Sierra foothills to the San Francisco Bay Area. The New Irvington Tunnel (NIT), a key component of the WSIP, is located east of Fremont in Alameda County, on the east side of San Francisco Bay. The NIT is a new 18,660 foot (5,689 m), redundant tunnel, 190 to 670 feet (58–204 m) offset from, and subparallel to the Existing Irvington Tunnel (EIT). Built between 1928 and 1932, the EIT was constructed with an unreinforced cast-in-place concrete lining and is vulnerable to damage in the event of a major earthquake along the two closest active faults. The Hayward Fault is located less than a mile west of the tunnel, and the Calaveras Fault is located half a mile east of the tunnel. Although the alignment does not intersect these faults, the shaking and sympathetic displacement along secondary faults that cross the tunnel alignment are potential hazards. The NIT provides a seismically reliable water transmission facility capable of withstanding earthquake damage and maintaining continuous water service after a major earthquake. The NIT also adds system redundancy and provides for operation flexibility of running water through both tunnels, or through one tunnel while the other is out of service for inspections and maintenance."

Jan 1, 2016

By Robert D. Brown

The purpose of this paper is to tell a story - and it is a story with a moral. My topic is Present Trends in the Tax Environment Affecting Mineral Development in Canada, and the first thing to recognize is that, with depressed metal prices and weakening western economies, taxes, in and of themselves, are not really the cause of the Canadian mining industry's present doldrums. But the character and level of mining taxes in Canada has had a profound influence on the development of the industry over the past decade, and the expectations of what taxes the industry will face in future years will influence the industry's further growth. My theme today is that, in Canada, our tax system has, in the past, served as a negative and destabilizing influence in the mining industry: it has contributed to a major short-fall in investment commitments and hence in the contribution which the mining industry can make to the Canadian economy, and the adverse effect on the industry of previous high tax rates was made far worse by the confusing, contradictory and perverse nature of the tax system itself. This is a story with some happy parts in it, and, in fact, governments in Canada did learn, haltingly and grudgingly, that there are limits on the amounts that governments could safely extract from the industry, and that some assurances of long term fiscal stability were necessary if investors were to be induced to make massive commitments which could only be recovered over very lengthy periods.

Jan 1, 1982

By Drummond Earley III

The U.S. Bureau of Mines is currently conducting laboratory experiments to study the reactions occurring during in situ leaching of oxide copper ores hosted by biotite-poor granite and biotite-rich granite porphyry. Detailed pre-leach and post-leach petrographic examinations of the rock samples are combined with the leach solution chemistry resulting from core leaching experiments to enable an evaluation of the various reactions which are responsible for the observed fluid chemistry. The information resulting from these laboratory studies is being utilized to support the design of the Bureau's ongoing field research project at the Santa Cruz deposit near Casa Grande, AZ. Atacamite and chrysocolla are the primary copper minerals present in this deposit, and both are readily soluble in the dilute 5% sulfuric acid solutions used in these experiments. In addition to the dissolution of copper minerals, biotite dissolution also occurs during the experiments, contributing K, Mg, Fe, and Al to the leach solution. The biotite dissolution appears to be non-stoichiometric, as it is progressively altered to vermiculite and finally, amorphous silica. While K, Mg, and Fe concentrations in solution steadily increase with time, Al quickly reaches a maximum, and then remains relatively constant for the remainder of the experiment. This suggests that Al saturation is achieved, and this Is supported by the presence of precipitated Al sulfate and aluminosillcate clay mineralization in the post-leach rock samples.

Jan 1, 1990

By T. R. Ellis

Considerable movement is afoot internationally to rationalize standards and regulations relating to valuations and the qualifications for valuation professionals. In July 2000 the International Valuation Standards Committee released expanded standards, and additional important improvements are planned by 2003. Possible updates to the International Accounting Standards (IAS) and potential adoption of IAS by the United States could significantly impact minerals appraisers. Standards designed specifically for mineral asset valuation are under development in Canada and the United States, with Australia's internationally respected VALMIN Code providing the benchmark. In the United States, the all-encompassing Uniform Standards of Professional Appraisal Practice (USPAP) is annually modified and continues to gain deeper acceptance, while the SEC holds fast to its 1981 rule prohibiting reporting of a quantitative estimate and value for non-reserve mineralization. Some important international trade agreements are driving actions to free the trade in professional services. In July 2000, an international workshop was held to initiate discussion on minimum qualifications for appraisers to work internationally. Pressure for uniform minimum qualifications and rules for professionals internationally will continue to build. The United States is historically among the slowest countries to implement such initiatives, with its state level licensure barriers having the potential to cause some of its professionals to be stranded in an international backwater. Structural change is needed in Australia's VALMIN Code to remove conflict with the latest International Valuation Standards. The mineral valuation standards developers of Australia, Canada and the United States should work jointly on updating VALMIN for global use.

Jan 1, 2003

By M. M. Fine

One of the most persistent topics at technical gatherings and in the recent scientific press has been the reduction of iron ore. To cite some of them, in May 1960, a symposium on the subject was sponsored by the Electrochemical Society. The proceedings, comprising two dozen papers, were later published.3/ More recently, November 1966, a similar gathering took place at Michigan Technological University, Houghton, Mich. The latest meeting was the International Congress on Production and Utilization of Reduced Materials, Evian, France, May 1967. If the volume of literature, symposia and conferences is a measure of industry concern, then current interest must be at a high level. To the casual observer of the metallurgical scene, the abiding and recurring attention to iron ore reduction outside the blast furnace must be somewhat puzzling in that so much research endeavor has resulted in so little commercial activity.

Jan 1, 1968