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By Dhananjay Kumar

In past, no serious attempts have been made to study the effects of operating environments on performance characteristics of a mining system. In this paper, proportional hazards model (PHM) analysis technique is introduced which can be used to analyze the effects of operating environments on the performance of a mining system. It can be used to select suitable materials, manufacturers or designs of items for a particular working environment. In this paper some applications of the PHM are discussed with examples from a Swedish mine. Its application for decision making in maintenance is also discussed.

Jan 1, 1992

By O. A. Bascur

Current competitive demands on the process industries stimulate the need for improved operating efficiencies and compliance to stricter governmental regulations. Emerging information technologies allow narrowing the gap between management business objectives and the process control level. Benefits come from enhanced energy management, operating costs reduction, enhanced scheduling of activities, reduced quality giveaway, enhanced market driven production and enhanced decision making. Plant management systems integrate economic performance monitoring by controlling the business rather than just throughput and product quality. Sound business based decisions about how to operate the plant can be achieved by adequate dynamic performance monitoring at the plant level and the enforcement of the desired targets at the process control level. This paper describes some of the key requirements to implement a process management system to meet stricter process performance standards. Extensions are made to facilitate conforming with regulations established by various governmental and industry monitoring agencies.

Jan 1, 1993

By James M. Johnson, David Landriault, Frank Palkovits

The term “Paste Technology” was first used in the late 1980’s. It was used to describe a high fines (15 wt% or greater minus 20 microns), low water content backfill material that could be transported underground through a borehole/pipeline distribution system (4” to 8” dia.) at a yield stress similar to fresh concrete (100 to 400 centipoise). This “Paste Backfill”, unlike slurry transported backfills does not segregate into separate solid and liquid phases at low pipeline transport velocities or upon disposal into the underground stope. Paste backfills can consist solely of fine material, or can include fines plus sand and aggregate similar to a concrete mix. Pipeline transport of paste requires that sufficient fine material (minus 20 micron content) is contained within the mix to lubricate the pipeline walls to create a plug flow condition. For concrete, the fine material is supplied through the cement addition to achieve high compressive strength. For paste, the fine material is generally available in large quantities in the form of mill tailings. The paste tailings can be transported underground for use as backfill or discharged on the surface in a tailings management facility (TMF). This natural abundance of fine grained material is not exclusive to mine tailings but is common to many waste streams in many different industries. This makes the disposal of many waste materials very amenable to paste pipeline transport and placement as a non-segregating slurry. The potential use of paste technology for a wider group of waste materials was realized by these authors and others over two decades ago. Through the effort of this small group the use of paste technology has expanded over the years to become recognized as a low cost, environmentally superior, and technologically controllable method of transporting and placing specific material waste streams with a low water content and high placement density. The high yield stress nature of a paste also lends itself well to the blending of one or more coarse waste materials into the fine waste material paste stream. This allows all the waste materials to be transported by pipeline, increases their placement density; decreases the supernatant release/treatment, reduces contaminant mobilization, hydraulic conductivity and oxygen/water reactivity through encapsulation in the paste matrix. The following paper describes the present state-of-the-art use of paste technology in the world today. It also describes future uses of the technology that are under development and speculates on the overall use of the technology for waste management in the future.

Jan 1, 2005

By Bruce R. Sutherland, Jim B. Ramsden, Gerry L. Bolton

Conductive metal powders are important building blocks for today's micro-electronic circuitry. Formulated into inks, they provide the interconnects needed to complete a complex integrated circuit and the means to enter the world of miniaturization. Traditionally, the inks have been based upon expensive metals such as silver, palladium, platinum and gold because of their excellent electrical conductivity and resistance to corrosion and oxidation. The use of a copper based ink, as an alternative to precious metal inks, recently has received considerable attention. Instability in the prices and limited supply of certain precious metal systems have driven up production costs, making the development of a lower cost copper system more attractive to manufacturers. However, lower production costs are on1 y real ized if performance and reliability can be maintained. While the development has been driven by cost, copper does offer some significant performance advantages over noble metal systems: conductivity as good as silver and 4W better than gold; leach resistance better than silver and equal to gold; stability at high frequencies better than gold or silver; strong film bonding characteristics; and compatibility with most solders. These benefits, however, do not come without cost. The inherently reactive nature of pure copper, while providing unique performance properties, makes it difficult to process. Unl i ke precious metals which can be fired in air, copper would oxidize and so requires special furnaces and atmospheres. Despite these difficulties, the transition from precious metal thick film systems to copper is gaining momentum. Manufacturers of high density, high performance circuitry are exploring the performance advantages of copper over gold and silver and the manufacturers of consumer products are considering the potential cost savings of copper over silver-palladium. Sherritt has developed a fine copper powder for this industry. Through association with the ink manufacturers, it has been found that performance properties of the ink vary with the physical and chemical characteristics of the powder. Production Process The production of very fine copper powders at Sherritt is based upon the disproportionation of cuprous ions as outlined in Equation [1] (1).

Jan 1, 1990

By E. L. Mann, Robert L. Virta

Asbestos is a generic name given to six fibrous minerals that have been used widely in commercial products. The six types of asbestos are chrysotile, crocidolite, amosite, anthophyllite asbestos, tremolite asbestos, and actinolite asbestos (Table 1). Chrysotile is the asbestiform variety of serpentine. Crocidolite, amosite, antho-phyllite asbestos, tremolite asbestos, and actinolite asbestos are the asbestiform analogues of riebeckite, cummingtonite-grunerite, anthophyllite, tremolite, and actinolite, respectively. Although amosite is an acronym for the Asbestos Mines of South Africa (AMOSITE) and does not specify a mineral type, it generally is composed of cummingtonite-grunerite asbestos so the terms are assumed to be synonymous.

Jan 1, 1994

By John C. Draper

The principal object of an underground coal mine transportation sys- tem is to move coal from the face where it is produced to the outside of the mine where it is prepared for market. In addition to the movement of coal, a transportation system must also move supply materials to the inside; it must move men in and out of the mine; and it must move rock and other debris out of the mine for disposal. Usually, mine haulage is divided into three categories named for the various areas of the mine served : 1) Pace Haulage. This is used at face from the mining machine to the intermediate transport system. 2) Intermediate or Secondary Haulage. Generally this is used between face haulage and main haulage. Sometimes this is merely an extension of the main haulage. 3) Main Haulage. This extends from the secondary haulage to the outside and is usually either a track or conveyor system, sometimes a combination of both. Transportation modes of coal in the various areas pose different problems, but the whole system must be synchronized. For instance, at the face the coal should be removed quickly from the various places to facilitate the movement of machines, whereas the intermediate system just passes the same coal on to the main transportation system. Selection of the transportation system must be based on the seam height, mining methods used to extract the coal, capacity required, ease of coal handling, and haulage efficiency. When driving rooms, mine cars can be used. They often simplify supply haulage and rock handling because they can also handle these items. Conveyors could be used and would have a greater haulage capacity but they cannot handle supplies easily or segregate the rock. When using a different mining method, such as longwall, mine cars cannot be used because there is not sufficient space to move the cars at the face nor can the cars haul the coal without delays which would cause excessive losses in production. As for ease of handling at a longwall face, conveyors are convenient because of their low height, ruggedness, and ability to operate while being advanced. Similarly, in low seam heights, conveyor systems are easier and more economic to operate than the regular track haulage because roof has to be taken down for handling mine cars of adequate size.

Jan 1, 1981

By J. F. Peterman, M. C. Roberts

The success of any industrial mineral project requires an accurate forecast of the demand fir the material as well as accurate projections of costs and prices. This paper develops a general method of predicting mineral requirements and applies it to the case of graphite. The basic method is to explain graphite consumption in each of its major uses by the output and manufacturing technology of the using industry. Once these underlying factors are determined, they can he projected to establish future requirements. This forecast is critical to the evaluation of a new source of supply, such as the graphite resources of Upper Michigan.

Jan 1, 1990

By N. Edmonson

During the last 30 years, a dramatic increase in the supply of byproduct sulfur substantially reduced the share of the market held by Frasch-mined (non-by-product) sulfur in North America. Even though Canadian sulfur production is not discretionary, the geographic remoteness from the large US markets and the high transportation costs associated with delivering sulfur to those markets has meant that Canadian producers act like discretionary producers in many important ways. They have effectively replaced the US Frasch producers as the cost-marginal sulfur source to large US markets. Implications of this change in market structure include more volatile sulfur prices and longer sulfur price recessions.

Jan 1, 1998

By Eleanore L. Nestlerode, James R. Guilinger

In April. 1990 Addwest Minerals acquired the Phillips Ranch sulfur property. The sulfur deposit, hosted by the Permian Castile anhydrite, occurs as two distinct elongate. parallel orebodies within a series of northeast-trending grabens. After completing a positive feasibility study, based, in part. on successful drilling programs by Addwest Minerals and previous operators, the decision was made to place the property into production. Utilizing an existing on-site kasch plant, plus significant portions of the recently purchased Texasgulf Comanche Creek Frasch plant. Addwest is currently constructing an 800 long ton per day Frasch mining facility.

Jan 1, 1992

By Manfred Jaeger, Klaus Ertmer, Walter Dietrich, Jochen Greinacher, Wilhelm J. Kogelmann

In Europe, novel low-cost excavator-mounted Multi Tool Miner (MTM) systems, consisting of cutter head, hammer, bucket and drill attachments permit one unit to perform multiple tasks replacing several purpose-built machines. At the Weser Tunnel in Germany, cross-passages between the twin tubes were excavated in frozen ground with a remote-controlled mini-excavator equipped with a quick-change cutter head, ripper tooth and bucket. In Switzerland at the N2 interstate near Basel, W. Dietrich AG enlarged a 2-lane tunnel to three lanes with a cutter head mounted on a special excavator. Blasting and heavy hammers were not permitted due to the closeness of the “live” twin tube. At the N20 Zurich bypass, the Joint Venture of Jaeger, Frutingerand AHB excavates highway tunnels, some with extremely large cross sections, conventionally. A cutter head mounted on an excavator removes the rock shattered by blasting precisely to the pay line, thus preserving the rock’s self-supporting capacity preventing subsidence and damages to water resources and buildings on the surface under low overburden.

Jan 1, 2003

By J. D. Miller, C. L. Lin

The appropriate software and hardware necessary to adapt an X-ray CT analyzer for the determination of coal washability was developed and successfully tested for well-characterized samples under laboratory conditions. Evaluation of the CT-based analyzer under simulated on-line conditions is also presented to verify the on-line capabilities of the newly developed X-ray CT analyzer for the control of coarse coal cleaning circuits. The investigation shows that the data obtained from CT washability analyses compare favorably with experimental sink float data. Further, image frequency was considered to evaluate the CT-Based coal washability analyzer for simulated on-line conditions. Specifically, the number of observations (image spacing) needed for accurate sampling and the total time required to perform the calculations for a representative data set were determined. Key words: Coal washability, Computer simulation, X-ray CT analysis

Jan 1, 2003

By Jorma Miettunen, Reijo Kalapudas, Pertti Koivistoinen

A new method for measuring the mill filling was developed by Outokumpu’s Pyhäsalmi concentrator during 1989-90. The method utilizes the power draw oscillation which is caused by the mill lifters. Each lifter bar causes a peak in the power draw and thus a continuous oscillation results. In a fixed time scale, the oscillation peaks will shift as the lifter bare hit the mill charge sooner or later depending on the volumetric filling of the mill. Thus the measuring method is based on the phase shift of the power oscillation. So far the measurement is utilized for maximizing throughput of the primary mills at Pyhäsalmi and Enonkoski concentrators and at Harjavalta slag concentrator. The paper describes the new method and the results achieved.

Jan 1, 1992

By J. W. Merks

Spreadsheet software is an effective tool for simulating dynamic stochastic systems such as mineral processing plants. The two-product formula is used to show how to set up a Monte Carlo simulation in a spreadsheet template and how to calculate variances of dependent variables. The key to a reliable and realistic simulation model is to obtain unbiased estimates for all independent variables and variances in the set that defines the stochastic system. Monte Carlo simulation is also a powerful tool for optimizing sampling procedures, for applying sensitivity analysis and for designing and evaluating experiments.

Jan 1, 2000

By Murat Budakoglu

Albite (NaA1Si308) is one of the important raw materials for the rapidly developing Turkish ceramic and glass industry. Prior to 1980, development of the ceramic industry in terms of raw material was dependent upon small-scale mining operations; in the last decade, these efforts have increased substantially. The aim of this study is to investigate the geochemical properties and distribution of albite occurrences in the Kocayayla district, which is about 12 km northeast of the town of Milas, about 50 km west of the city of Mugla in southwestern Anatolia. Kocayayla is also well known for its famous ancient city, Labranda. The field area is located in the Menderes Massif, which was formed by major tectonic events during the Late Proterozoic and subsequent periods. The target area was studied to prepare a detailed geological map (scale, 1:10,000), and to determine the formation of albite-mica-schist-quartzite borders in the host rock gneiss. To do this, systematic sampling of albite was done in the two main areas, the Sarikaya and Yumruta? regions. In the study area, albite zones are scattered within an area of about 20 km2, and they extend in a northeast-southwest direction; mica-schists and quartzite veins accompany these units. Mineralogical observations show that quartz is the main mineral associated with albite. In the ceramic industry, the albite + quartz assemblage is well known and is classified as "standard" or "super type," depending upon the content of TiO2 and Fe203. In this study, the Sarikaya albites (profile I) exhibit remarkably lower TiO2 (0.15% on the average) values contrasted to that of Yumruta? (profile 11; 0.24% on the average), whereas Fe203 values vary slightly from 0.076% to 0.085% in both regions.

Jan 1, 1999

By R. Fedel-Moen, R. W. L. Kimber, B. D. Williams, S. R. Ragusa

The use o f cyanide to extract gold from ores is widespread. In the process of extracting gold, cyanide may form metal cyanide complexes with a variety of other metals present in the ore. This study was carried out to investigate the biodegradation of the Cu(I)-cyanide complex and tetracyanonickelate under varying pH and nutrient additions. Detailed studies using shake flask cultures and bioreactors showed that naturally occurring bacteria residing on gold-leach-pad ore uti¬lized the Cu(I)-cyanide complex (CuCN) and tetracyano-nickelate, Na2(NiCN4), as carbon and/or nitrogen sources. Ammonium-nitrogen (NH4+-N) and/or cyanate (CNO-) accumulated in solution as the metal cyanide complexes were degraded. The accumulation of cyanate as a product is a concern due to its toxicity. Degradation rates were increased if a growth substrate (peptone, 0.1%) was added to the medium or if bioreactors were primed with peptone before addition of the metal-cyanide complex. Tetracyanonickelate was degraded at pH 8 without added peptone, but it was not degraded at pH 10. The addition of peptone was required for degradation of the Cu(I)-cyanide complex at pH 8 and pH 10. At pH 8, the addition of peptone resulted in the accumulation of cyanate, whereas, at pH 10, cyanate was not detected in the cultures. Biodegradation of metal-cyanide complexes was faster (approximately 1.5 to ten times faster) in bioreactors than in shake flask cultures. The addition of peptone was not required for degradation of metal-cyanide complexes in bioreactors. However, priming the bioreaetor with peptone resulted in higher metal-cyanide degradation rates over multiple cycles.

Jan 1, 2000

By B. T. Stanley

Traditional methods of creating a water tight shaft liner involve the use of segmented or welded steel. When shafts are located in ground that exhibits extremely difficult conditions of high water inflow and hydraulic pressure, composite liners are often combined with ground freezing during construction. The authors were searching for a cost effective and more flexible solution to hydrostatic liners design than the traditional concrete/steel composite design used so far. Searching through new technologies developed for tunneling applications, sprayed on membranes systems seemed very promising but were not developed for the specific circumstances encountered in shaft sinking applications where ground freezing is involved. Even though freezing is a very effective technique, it creates adverse temperature conditions for the application of spray on membranes. In addition, application and hydrating cure times for those membranes products ranged between six to twenty-four hours under ideal conditions (usually temperatures well above freezing point), which eliminated them from consideration in a shaft sinking cycle. While researching different spray on membrane materials, it was discovered that Stirling Lloyd Polychem Ltd. has developed and proven a different membrane material for waterproofing liners in different tunneling applications. The characteristics of the membrane exceeds the pressure parameters encountered in frozen shaft sinking operations, and the chemical cure times were reduced to one hour per layer which worked well into the shaft sinking cycle times. More over their system included a quality control procedure that allowed insuring integrity of the membrane at application time, a very desirable feature for shaft liner construction. However, the frozen rock surface still presented an unknown in the cure time and stability equation. As all membrane products a shotcrete substrate is usually required prior to application. The hypothesis used by the author was to use this shotcrete layer, not only as a substrate, but also as a thermal insulation against the frozen rock and the membrane during both application and curing time. The authors knew from experience that shotcrete could be applied successfully over frozen rock. But the shotcrete temperature curve over time was unknown and no information were found in the available literature. Testing was required to determine whether a suitable mix of shotcrete could be applied to the frozen shaft wall to provide enough heat of hydration for a suitable period of time to create conditions suitable for membrane application and curing.

Jan 1, 2012

By Jean-Luc Cornet

Downhill, or regenerative conveyors have always been a challenge to the design engineer due to their natural instability under load. The last decade has seen the appearance of high tonnage, high negative lift conveyors with several hundred meters of drop. These conveyors have made necessary the development of new braking systems and intelligent drive controls to address their starting and stopping requirements under various load conditions. This paper describes the critical design criteria of large regenerative conveyors and some of the advances in mechanical braking systems and drive control technology developed by Conveyor Dynamics, Inc. (CDI) to address their specific requirements.

Jan 1, 1993

By Erie F. Wolstenholme

The purpose of this paper is to describe work undertaken, within the System Dynamics Research Group at Bradford Management Centre, into the development and application of a System Dynamics model of an international mineral industry; aimed at providing a basis for analysis of the interrelationship of supply, consumption and price over time, under different production and stocking policies. A review is presented of some of the major characteristics and problems associated with such industries. This is followed by an outline description of the model and the way it has been applied to examine various supply responses, in the light of changing consumption patterns. Demonstration results deal with model validation and with analysis of international buffer stocks and conflicting supply policies on the historic situation in the copper industry.

Jan 1, 1979

By Neville G. W. Cook, John Kemeny

Utilizing the principles of elastic-brittle fracture mechanics, stress-displacement relationships are derived for an elastic solid containing a slip plane consisting of various configurations of collinear arrays of cracks. These models take into account the heterogeneous nature of slip planes as observed in the lab and in the field, and are relevant to the behavior of rock containing faults, joints, bedding planes, and fractures. All of our models exhibit slip weakening behavior, and show regimes of both stable (aseismic) and unstable (seismic) deformation. For given configurations of cracks and applied boundary conditions, our results show explicit ly the energy released through unstable crack growth. For instance, it is found that two equal length cracks growing together release more seismic energy than, say, a large crack growing into a small crack. Also, by allowing cracks to coalesce, our models show multiple stick-slip events without crack healing or other geochemical means.

Jan 1, 1986

By Alexander I. Feldman, Michael S. Kucker, Robert A. Robinson, Harvey W. Parker

An extensive geotechnical monitoring program was used to assess ground and liner behavior, provide input to a Disputes Review Board, and verify design assumptions during construction of the Mt. Baker Ridge Highway Tunnel along I-90 in Seattle, Washington. The stacked-drift tunnel liner was constructed with twenty-four 2.9 m diameter concrete-filled drifts forming a semi-flexible compression ring, followed by excavation of the 19.4 m diameter soil core. Instrumentation data was used for monitoring hillside stability, liner deflections and loads, impacts on adjacent highway tunnels, for back analyzing soil properties, and for helping to limit construction-induced settlements to about 6 cm.

Jan 1, 1987