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By R. L. Pozzo

A previous investigation showed that corrosion currents estimated from polarization curves for the pyrrhotite-grinding media system under abrasion correlated well with corrosion currents estimated from marked ball wear test data by applying the Faraday's Law. Freshly abraded metal debris were magnetically attracted to pyrrhotite and lowered the rest potentials of the mineral particles, thereby affecting the corrosive wear. The investigation was extended to explore the interactions between a nonmagnetic sulfide mineral, pyrite, and abraded metal debris and their effects on the corrosive wear mechanism. The electrochemical behavior of a three-electrode system involving pyrrhotite, pyrite and grinding media was also investigated as a first step towards elucidating the nature of interactions that occur in the grinding of complex sulfide ores.

Jan 1, 1987

By A. W. Randall

Geological Aspects of Ore Reserve Estimates of Pine Point District Zinc- Lead Deposits, N.W.T. Zinc-lead ores of the Pine Point District, Northwest Territories, Canada are hosted in paleokarst cavities within a Middle Devonian carbonate barrier complex. Of the nearly 100 deposits found, most are irregularly distributed along two main regional stratigraphically controlled trends. The ores, which occur predominantly as open space filling, form deposits most of which average one million tonnes in size with an average grade of 10% combined zinc plus lead. Geological features related to karsting control not only distribution of deposits but also their shape, size and grade. The higher grade ore in these deposits generally occurs in a relatively small core area. Consequently, accuracy of reserve estimation is dependent on drill hole density and understanding of karst geometry. Several case examples will be reviewed to demonstrate the relationship between shape, size and grade of deposit, geological reserves and drill hole density, along with a discussion of geological ore reserve estimation methods.

Jan 1, 1985

This paper presents a virtual prototype for the stress analysis of cable shovel components based on combination of flexible and rigid body approach. The general mechanical system of the cable shovel is modeled as a multi-body system with rigid and flexible bodies. The relevant theories applied for the dynamic model are described in terms of Lagrangian multi-body dynamics and finite element method. A virtual prototype of the cable shovel is built in the Automatic Dynamic Analysis Mechanical System (ADAMS) environment, which allows visualizing the motion of general mechanical system and analyzing the dynamic stress of structural components of the cable shovel. An example is given to perform dynamic stress of durability analysis for the boom and handle. Attention of this study is devoted to the mechanisms of damage of the cable shovel and also the critical high stress areas. Keywords: Cable shovel, Von Mises stress, Virtual prototype simulation, Stress virtualization.

Jan 1, 2009

By A. Duerksen

Surface coal mining in West Virginia has supplied energy to the eastern coast of the United States for over a century. The coal mining industry has been forced to adapt as societal demands regarding health, safety, and environmental impacts have changed with time. More recent pressure has called for another iteration of change: long-term post-mining sustainability. The research presented in this paper investigates one potential solution?or component of a solution?to improve mining sustainability in Appalachia: post-mining wind power. This paper intends to demonstrate and explain the feasibility of synergistic mine closure and wind development. Wind conditions at three reclaimed mine sites in West Virginia were monitored in order to develop representative case studies for post-mining wind power. This paper contains a summary of the literature consulted to plan the site assessments, the methodology employed to execute them, the analysis steps undertaken to derive conclusions, and a discussion of all findings. This research has found that significant cost savings can be yielded from synergistic mine closure and wind development, as compared to greenfield wind development. Though wind conditions themselves remain the primary driver for site feasibility, post-mining wind power is a practice with significant promise for improving project economics, contributing to renewable energy development, enhancing company-community relations, providing local employment opportunities, and exemplifying sustainable business practices in Appalachia.

Jan 1, 2012

By R. D. Hansen

This paper discusses the influence of frother type and dosage on recovery/selectivity in coal/sulfide mineral flotation as a function of particle size. It is shown that different frother structures do exhibit quite different but consistent performance characteristics depending on the underlying particle size ranges involved as well as the dosage levels of both the frother and collector. The data presented on existing commercial frothers end some new special purpose experimental frothers is used to illustrate some general operator guidelines on proper frother selection and use.

Jan 1, 1985

By W. M. Shaver, W. R. Dengler, F. A. Edwards

INTRODUCTION The Macassa Division of Lac Minerals Ltd. is a high grade gold mine that has been operating in Kirkland Lake, Ontario for the past 51 years. It produces approximately 120,000 tonnes of ore per year, averaging approximately 18.7 grams per tonne (0.45 ounzes per ton) of gold. Over the years, the ore body has been developed to a point where mining takes place below the 1,220 m (4,000 feet) elevation and 1,830 m (6,000 feet) west of the original shaft. The mine is currently serviced by two surface and two winze shafts. (Figure 1). The ore body extends below the 1,930 m (6,400 feet) Level which is the bottom of the existing mining operation. An ambitious underground exploration program has substantially increased these reserves. Concurrent with the discovery of greater reserves, has been rapidly escalating mining costs, particularly labour which constituted 66% of the total cost in 1981. These costs continued to escalate as the major proportion of mining was carried out to the west, far away from the existing hoisting systems. This required three lift hoisting for men, materials and ore. I n addition to the increased travel time and ore handling expense, increased humidity and temperature and ventilation and compressed air losses have added to the inefficiency of the operations. As a result, studies were initiated in 1980 to assess the future of the Macassa operation.

Jan 1, 1985

By I. G. Gonçalves

For most industrial minerals, the color is directly associated with economic value. In terms of physics, the principal property that defines the term ?color? is the intensity of light reflected (or transmitted) by an object over the visible band, comprehended between 400 and 700 nm. This reflectance spectrum serves as the starting point for a variety of color-describing factors, the most common in the mineral industry being the brightness (TAPPI, 1977 and 1986) and the L*a*b* system (HunterLab, 2008). Quality specifications for mineral products are usually based on these colorimetric parameters. This market is becoming increasingly more selective and demanding over the quality of raw materials and alongside the traditionally controlled characteristics, such as particle size distribution and chemical composition, a trend exists towards the establishment of increasingly more strict specifications for the optical properties of these materials. This is due to the fact that most plants consuming these industrial minerals incorporate them into products in which the visual appearance is controlled. For these plants, most of them being the manufacturers of plastics, paper, paints, and ceramics, variations in the color of mineral materials result in difficulties to achieve the right color in the final product. Therefore, these plants set strict specifications for colorimetric parameters such as whiteness and yellowness, as well as colorimetric coordinates like L*, a*, and b*. For the manufacturer of industrial minerals, this translates into difficulties simply because many of these parameters are usually alien to the tradition of the mining industry. The main quality parameter in the kaolin industry is brightness, which is a weighted average of reflectance values over the range of 400-510 nm (TAPPI, 1977). Due to the lack of a better property, producers tend to use brightness to also assess the quality of the in situ ore and along the processing operations. However, the unprocessed kaolin is often accompanied by ?contaminant? minerals. For Brazilian kaolins, which are the object of this study, the most important contaminants are hematite (Fe2O3), goethite (FeOOH), and anatase (TiO2). Each of these contaminant minerals has a distinct color and behaves differently during the processing of the kaolin ore. Hematite and goethite in particular are particularly strong pigmenting agents and at concentrations as low as 100 ppm they can make the difference between a high-quality white pigment product for paper coating and waste material. As each Fe-bearing contaminant has a different color and responds differently to processing operations (for example, magnetic separation, chemical bleaching, selective flocculation, and/or flotation in the case of kaolin), the in situ brightness tends to show a poor correlation with the brightness of the final product. Brightness measurements are sometimes complemented with X-Ray Fluorescence (XRF) analysis of Fe and Ti, but the total oxide content provided by XRF is also poorly correlated with product quality because Fe may be in the form of goethite, hematite, or inside the crystalline structure of kaolinite. Thus, a more robust technique capable of distinguishing each mineral phase is desirable. Diffuse reflectance spectroscopy has been used to analyze iron oxide/hydroxide content both qualitatively (Torrent and Barrón, 2003; Liu et al., 2011) and quantitatively (Jiet al., 2002 and 2006). These authors correlate slopes and inflection points at characteristic absorption bands with oxide/hydroxide content in natural soils. The approach presented here involves the extensive use of the Kubelka-Munk (K-M) theory, which has been used for color matching (Schabbachet al., 2009 and 2011) and particle size determination (Otsuka, 2004) in a simplified version. Unfortunately, the scattering constant S is very difficult to measure for dry powders, because the equations require a thin layer of material. Attempts have been made (Gonçalves and Petter, 2007, and Gonçalves, 2009) but the experimental errors tend to be high. Thus, this paper aims to develop a tool for the quantification of contaminant minerals in kaolin based on the K-M theory without resorting to measurements over thin layers. This tool is based on a new two-constant approach, which takes into account differences in scattering between materials over the whole measured spectrum. The experimental dataset consists of the reflectance spectra of mixtures between a bleached kaolin and synthetic Fe pigments.

Feb 27, 2013

By V. Svalbonas

Everybody has an opinion what the quality of a grinding mill head casting should be, yet extremely few take the time, or get the opportunity, to compare their opinions against fitness-for-purpose data. The real question is not how flawless the casting should/could be, but rather how long will ?this? casting survive in operation. To validate an opinion on this topic one needs either extensive historical data, or comprehensive experimental data, or preferably, a combination of both. The same data can also be used to establish the conservativeness, or lack thereof, of analytical prediction methods.

Jan 1, 2009

By Frederic Chavan, Hans Jakob Windier, Shane Yanagisawa, Willy Ritz

The Zurichberg twin track tunnel is the main segment of the Swiss Federal Railway's new expressline. A heavy concrete lining with a circular cross-section was chosen to cope with the swelling tendency of the surrounding rock. The 4,356 m (14,300 ft) long, 11.52 m (38 ft) diameter tunnel was driven using a shielded Robbins TBM. A 1.20 m (4 ft) wide, 25 cm (10 in) thick precast lining was placed from within the shield tail as the excavation progressed. Tunnel excavation and initial lining operation were completed in 18 months, averaging 11.86 m/day (40 ft/day) in two nine hour shifts. After breaking through, the final 28 cm (11 in) thick concrete arch lining was cast in place.

Jan 1, 1989

By D. D. Runnells

In order to establish meaningful remediation goals and monitoring programs in areas disturbed by mining, it is desirable to determine the natural metals concentrations that existed in the area prior to mining. At Iron Mountain, California, several natural sources exist for acid drainage and loading of metals to Slickrock and Boulder Creeks. This paper describes methods to determine the contribution of copper and zinc to groundwater and surface water from those sources, including natural gossan rock outcrops, mineralized bedrock, and colluvial materials. Methods used include evaluation of: 1) historical information, 2) literature values of unmined, mineralized areas, 3) analyses of water from monitoring wells, 4) leaching studies, 5) statistical analysis, 6) isotopic studies, and 7) identification of background by elimination of mining sources. Results from this natural background determination show that Boulder Creek and Slickrock Creek carried elevated concentrations and loads of copper and zinc prior to mining activities. With repeated rinsing of reclaimed and remediated mine materials by rainfall, there will be a diminishing contribution from residual waste rock and tailings at Iron Mountain, and natural background will become an increasingly larger proportion of the total load.

Jan 1, 1999

By Enrique Levy

Central America is graduating this year into large scale mining with the start up of Inco's multi-million dollar nickel laterite processing plant in Guatemala. In the other extreme of the Isthmus in Panama Texas Gulf Sulphur is doing check diamond drilling and foundation test drilling at the Cerro Colorado copper porphyry. The higher price of gold and silver has spurred development and exploration of several small precious metal mines. The purpose of this presentation is to make a brief resumé of the most important mines operating in the area and a list of significant exploration projects. Also, tables will be shown to compare mining codes and taxes. Unfortunately these tables lack information on Panama. Before starting I like to express my appreciation to Kennecott Copper who permitted the use of some of the data compiled by the author on their behalf during the year 1975. Other persons which did not want to be named also have my gratitude.

Jan 1, 1977

By R. L. Grayson, S. S. Eslambolchi

"In making strategic economic decisions, it is important for a mining company to gain insights on the impact of significant political, social and economic issues when planning for present and future mines. The size of any mine, measured by the average number of employees working in the mine, will likely vary according to the pressures generated by the significant issues from one year to another. The objective of this study is to develop a model that represents U.S. underground coal mine size transitions during the period 2002-2012 using data derived from the MSHA databases. Coupled with information on significant issues over the past ten years, this model is used to gain insight on the impact of the issues on mine sizes. Results indicate that the structural impact of the combined driving pressures can be discerned by examining the year-to-year stability of mine-size categories. The effects of The MINER Act, the Obama Administration environmental policies on coal, and the coal market are evident. The lessons learned from these analyses give good insights on what the industry and market responses have been on the structure of the underground coal industry over the period of study. INTRODUCTION It is apparent that key driving issues affect the structure and viability of the coal industry. The driving issues may be political, social, and/or economic in the final analysis, but are generally rooted in reaction to dramatic and publicized events or movements. Mine disasters, an increase in miners’ disease prevalence, strife in the coal fields, and negative environmental impacts on air, land or water can capture the attention of the media and the public. Some of the issues occur over a long period of time, like the current global climate change movement. The coal industry veteran can sense the changes in political and social sentiment, and attempt to react to the economic repercussions; however, the insights from the media and from unique combinations of driving pressures are difficult to fathom. Thus decisions made on inadequate information related to the driving pressures and their likely impacts could lead to missteps in corporate and market restructuring. One way to gain some more insight on the potential impacts is to examine the complicated restructuring of mine operations in reaction to the driving pressures of the recent past. This paper examines an 11-year history of the changes in the underground coal industry structure, as reflected by changes in the numbers of mines in various statuses by mine-size categories. Superimposed on the results of mine-size changes is a mapping of the key driving pressures that occurred over the same period, 2002-2012. It is assumed that using this methodology, some important insights can be gained on the immediate and delayed responses to the driving pressures during that period."

Jan 1, 2015

By H. V. Fairbanks

It is estimated that millions of tons of coal fines are unsaleable each year due to difficulty of drying them economically with conventional mechanical dewatering and thermal drying equipment. The difficulty is due to the fact that coal of small particle size presents a large surface area with polar groups which have a great affinity for water. In order to remove this water thermally, a high temperature is necessary which oxidizes the surface of the coal. This substantially reduces the heating value of the coal. If drying could be satisfactorily carried out at a lower temperature, much more of the heating value of the coal fines could be retained. It was conjectured that acoustic energy applied during the drying process might prove to be of value since acoustic energy has the property of producing cavitation at a liquid-solid interface when the intensity is sufficiently great. This cavitation process produces water at room temperature which can be carried away from the solid surface by a flow of relatively cool air. Hence, moisture removal is made possible at a lower temperature.

Jan 1, 1966

By A Pettersson

LKAB owns and operates two of the largest underground mines in the world in Northern Sweden. In Malmberget, with a production capacity of about 30,000 t/day of iron ore, the current main 815 m haulage level is rapidly approaching the end of Its life and plans are being made for its replacement on the 1000 m level. Due to the separation of the orebodies, trucks have been chosen for transporting the ore from the orepasses to the crushers. The trucks currently in use have a capacity of 120 tons. To increase the efficiency of the loaded haul, the new main level will have a favorable slope from the drawpoint locations to the crushers. From the new level the crushed ore will be transported by conveyor to the 815 m level for hoisting to the surface. The paper discusses the planned mining and transportation system.

Jan 1, 1998

By D. A. Fenton

The reliability of large diameter, high horsepower ball mill is paramount when large production and minimum downtime is required. The 17 ft. x 56 ft. double compartment ball mill at St. Lawrence Cement Company has the first gearless drive built in North America and has the world's largest hydrodynamic bearings currently built and running. The machine has seen three years operation and has met its specifications. The mill was designed by Aerofall Mills Limited and the gearless drive built and designed by the Canadian General Electric Company. This paper discusses the operation of the first North American installation of a gearless drive ball mill from the mechanical, electrical and process aspects.

Jan 1, 1977

By John E. Litz

Since the 1974 introduction of catalytic converters to automobiles in the United States, more than 150,000 kg (5,000,000 oz) of platinum, palladium, and rhodium have been used in the converters. An estimated 8 to 10 million converters are being used annually in the United States, each containing from $5 to $15 of PGM metals. In addition, use of converters is beginning in Europe which will significantly increase the quantity of PGM used. Two basic types of catalysts for converters are being used: pellet and monolithic. The pellets are small, discrete spheres or cylinders of gamma-alumina coated with platinum group metals, Figure 1. The monolithic are honeycombs of a cordierite, A13(Mg,Fe)2Si5AlO18, base coated with gamma-alumina and subsequently with platinum group metals, Figure 2. Pellet catalysts are being used by General Motors and American Motors; whereas Ford and Chrysler are using monolithic catalysts. The table below compares the PGM content and value of the catalysts.

Jan 1, 1986

By Timothy C. Richmond

The Stillwater District is located in south central Montana approximately 75 miles southwest of Billings, the state's largest city. It lies along the northeast front of the Beartooth Mountains and is within the boundaries of the Custer and Gelatin National Forests. The district contains some of the nation's most spectacular mountain scenery. Montana's highest peaks, including 12,799 foot Granite Peak, rise a few miles south of the area. Much of the district is located on a gently undulating plateau which averages 8500 ft. above sea level, broken by hills up to 10,000 feet and slashed by glacially carved canyons, some of which are more than 3,000 feet deep.(Fig. 1) Immediately to the north and east, the land falls away to the Great Plains, stretching unbroken to the Mississippi River. Two major tributaries of the Yellowstone River, the Stillwater and Boulder Rivers, traverse the area and several large streams originate in the district itself. Access to the high mountain country and the adjoining Beartooth Primitive Area is restricted to a few horse and jeep trails continuing from the terminus of improved roads in the bottom of the Stillwater and Boulder Valleys. Hunters, fishermen and cabin owners make intensive use of the area along its improved transportation routes, but hikers seldom venture more than three miles beyond the end of the roads. People from the Billings area are the most frequent visitors.

Jan 1, 1974

By D. P. Patil, B. K. Parekh

Water is the mainstay for beneficiation of fine size coal and minerals; however, it is also the least desirable constituent in the final product. The basic concept of the novel process described in this paper is based on the differential surface heat absorption capacity of individual particles, which differs for different species of mineral. When a mixture of fine material is exposed to a radiant energy source, the various solids components present in the mixture will absorb heat energy depending on their composition and there will be difference in the surface temperature of the particles. When this differentially heated solid mixture is placed on a moving belt, which is coated with low temperature melting resin, the hotter component of the mixture will stick to the belt and relatively cooler will stay free on the belt and fall off at the end of the belt run. Experiments were conducted with pyrite, coal and quartz of 6 x18 mesh particle size. The goal of the test program was to find the optimum conditions at which there exists a required temperature difference between minerals and coal particles by controlling the operating and system variables. Preliminary tests results showed that there is a potential for separating mineral matter from coal using the thermo-adhesive separation technique.

Mar 2, 2022

By David L. Veith

As the basis for the State of Minnesota's Regional Copper-Nickel Study environmental evaluation, hypothetical mine models were developed ranging in ore capacity from 5.35 to 20.00 x 106 mtpy. Open pit and underground mining operations were defined utilizing conventional methods of ore extraction. Processing of the copper-nickel sulfide material involved conventional bulk flotation of the valuable minerals, with maximum water recycle And tailing disposal. Flash smelting and electrolytic refining of the concentrate resulted in 0.10 x 106 mtpy copper plus nickel metal, plus associated cobalt and precious metals. Variations in model parameters allowed environmental trade-offs to be identified.

Jan 1, 1980

By G. H. K. Schenck

Weather changes of a daily, weekly, or seasonal period affect mineral production and cause significant losses that are considered unavoidable. Private weather forecasting services are available on a contract basis that can significantly reduce the uncertainty associated with weather-induced changes in the production of and demand for minerals. This paper provides examples of current practice and reviews the opportunities that await those producers who incorporate weather services as an integral part of their operating, scheduling, and planning procedures. Private weather forecasts can be highly accurate because atmospheric trends such as conditions and movement tend to persist and are related to previous meteorological events. Commercial meteorological services are prepared to deal specifically with a mineral producer's special problems (Table 1). Tactical use of private forecasts is a major advance over the severely restricted value of public forecasts which, of necessity, are general in nature and cover a dispersed geographic territory. Private weather services provided on a consulting fee basis offer the mineral producer the opportunity for tactical and strategic response to weather conditions at an acceptable cost. This contrasts with the too-frequent current tendency to view weather as a random variable the costs of which are unknown and about which nothing can be done.

Jan 1, 1970