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By G. K. Roset, L. R. Woodland, J. A. Stevenson, G. J. Hodges

The Stillwater Mining Co. (SMC) is a partnership of Pittsburg & Midway Coal Mining Co. and Manville Corp. Since the summer of 1990, SMC has operated a precious metals smelter at Columbus, MT for further upgrading of concentrates from its platinum-palladium mine. The facility's gas-cleaning system utilizes "oxidation/dilute-mode," dual-alkali scrubbing technology to capture sulfur oxide gases from the process gas streams. This paper describes the rationale for selecting the dilute-mode, dual-alkali system and summarizes the design parameters. Also discussed are the startup problems encountered and their solutions.

Jan 1, 1993

By H. S. Kibler, A. E. J. Gallagher, J. J. Sebesta

A review will be made of the nature, value, costs, and factors associated with industrial minerals production in general. Comparisons will also be made between some of these data and similar criteria for metallic mineral production.

Jan 1, 1987

By V. Dezelic, D. B. Apel

This paper describes the results of laboratory and field experiments conducted to determine the applicability of Ground Penetrating Radar (GPR) for the assessment of the strata thickness and for the identification of separation between bedding planes in stratified rocks. The knowledge about the extent of such separation in the roof layers and information about roof lithology can be used to determine the roof support requirements for underground mines where stratified rocks are present. The laboratory and field experiments were conducted at the Rock Mechanics Laboratory and the Experimental Mine at the University of Missouri-Rolla. The 1.5 GHz high resolution, shallow depth GPR antenna was used for all of the experiments.

Jan 1, 2004

By John P. Fillion

This paper will present an overview of conveyor haulage systems. Technical and economic feasibility will be examined as conveyor haulage is applied to large western surface coal mines. Theoretical analysis and actual cases will be presented from NERCO Coal Corp. experiences in bringing this application to their Western mines.

Jan 1, 1989

By Muammer Kaya, Derya Oz

The main objective of this study was to remove printing ink from waste newspaper and improve the de-inked paper brightness as close as the unprinted paper by bleaching agents. This paper summarizes results of laboratory investigation into the de-inkability of newsprint printed with offset printing. Different chemicals and process parameters were varied to assess the effect on the brightness and cleanliness. The operations involved in de-inking process are briefly described and some of the problems being encountered are discussed.

Jan 1, 1995

By D. D. Lei, H. Sevim, S. M. Gwamaka

Three transportation and handling alternatives for delivering dry coal combustion residues from power plants to underground coal mines were evaluated both technically and economically. The objective was to transport, handle and inject the residues into the old workings of the mine at minimum cost. This was accomplished in the following two steps: simulation models were developed and utilized in identifying technically feasible designs for each alternative and the technically feasible designs were economically evaluated to obtain the cost per ton of material transported. An analysis was conducted for varyous distances and tonnages to reveal favorable operating ranges for each alternative.

Jan 1, 1998

By R. Hogg, T. F. Dumm

A simple shape description scheme has been developed which has the specific aim of distinguishing between angular and more rounded particles. The procedure involves fitting a general polygon (usually about 20 sided) to the particle profile. Geometric shape descriptors have been defined based on variations in the angles between adjacent sides and their radial displacement from the particle centroid. A two-parameter shape description, incorporating an angular variabli1ity and an elongation index, has been shown to be clearly consistent with visual observations. A single-parameter angularity index has been shown to be very sensitive to small differences in particle roundness and seems to provide a better description of angularity than other approaches such as signature and fractal analyses. The scheme has been applied to three sets of fine quartz particles produced by different grinding procedures. The results indicate that the technique is capable of distinguishing between angular and re1atively rounded particles and can quantify their specific shape features.

Jan 1, 1991

By William J. Kohan

Milling has traditionally been considered more art than science. In the last 10 years, significant improvements in process equipment have been made and we are finally taking significant steps toward approaching grinding as a science. Two machines have been at the center of this development. These are the roll press and the high efficiency separator. The former can be considered as a new technology or adaptation of existing i.e. roller mill. The latter is clearly an improvement of existing technology. Other machines have been introduced to a lesser degree and later. Among these are the CKP and Horomill. The purpose of this paper is to provide an over- view of the currently available modifications for operating systems and options for new milling circuits with some comments on their application and history.

Jan 1, 1997

By Y. Nakahiro, T. Wakamatsu, M. S. Elsalmawy

The flotation of quartz, feldspar and alumina was studied as a function of pH when using N-alkyldiamines as collectors. The lengths of alkyl chains of diamines were 8, 9, 10, and 12 carbon atoms. It was found that shorter hydrocarbon chain length of alkyldiamines has stronger tendency to float quartz while the feldspar responded poorly to flotation with these collectors at high pH values. The effect of addition of nonionic surfactant of Brij type, when using dodecadiamine as collector, was investigated. Flotation studies in the absence and in the presence of sodium dodecylsulfonate were carried out. These studies have indicated that sodium dodecylsulfonate, in the concentration studied, functions as strong depressant for feldspar.

Jan 1, 1995

By Ted H. Eyde

Specialty sand and bentonite are produced in the plateau province from the Bidahochi Formation near Sanders, Apache County, Arizona. It appears that deposits of both sand and bentonite formed during the Pliocene in fluvial and lacustrine environments, respectively, along the west side of the Defiance Uplift. The bentonite is an alteration product of airborne vitric ash that fell or was washed into lakes. In the Cheto district, the individual bentonite horizons, which range from less than a foot to more than 10 feet thick, are restricted to the position of the medial volcanic member. Bentonite production began at the Allentown mine in 1924 and the Chambers mine in 1926. In 1933 strip mining of the extensive deposits in the Cheto district commenced. Production increased each year to a peak of 270,000 tons in 1957. As a result of the introduction of synthetic zeolites into petroleum refining, production declined. About 40,000 tons of bentonite are currently produced from the district each year. Bentonite is shipped out of State for processing into desiccants, thickeners, and acid-activated clay products. The specialty sand was derived from Permian sandstones and deposited by streams draining the Defiance Uplift. Although stream channels are usually restricted to the upper member of the Bidahochi, stratigraphically above the bentonite horizon, a few actually cut through the bentonite. The well-sorted sand, suitable for use as a proppant in hydraulically fractured oil and gas wells, is localized in elongate lenses along the margins of the channels. These lenses range from 5 to 50 feet in thickness and often extend thousands of feet in both width and length. The sand is about 97 percent silica, has a yield of 40 percent in the minus 20 plus 40 mesh size fraction, and has a roundness of 0.6 to 0.7 on the Krumbein scale. Production of this sand began about 1961. All of the current production, which amounts to about 40,000 tons per year, is sold in the petroleum-producing area near Farmington, New Mexico.

Jan 1, 1987

By A. H. Hassan

Stibiotantalite is a relatively rare mineral not commonly found in the major tin districts of the world, and its separation characteristics have not been documented adequately in the literature.

Aug 1, 1979

By H. L. Hinds

Economic pressures to increase production to profitable levels reduced the Homestake's gravity recovery and overall recovery to un-acceptable levels. The operation of the Home-stake gravity gold circuit has increased gravity gold recovery to over 50%, improved overall recovery and increased mill availability for increased tonnage. The gravity circuit consists of three gravity gold recovery stages. The Circuit has four (4) duplex jigs, four (4) belt concentrating strakes and four (4) concentrating tables.

Jan 1, 1989

By Corale L. Brierley

The depressed economic condition resulting from normal cyclic behavior, a more fundamental structural alteration, or both, is a mandate for change within the mining industry. Although several strategies for change have been proposed, the option of applying high technology processes to this smokestack industry offers the greatest opportunity for regaining global competitiveness and a new vitality. Research and development to secure new technologies require a corporate commitment for substantive change, a tech¬nologically enlightened management, a well¬funded and stable science and engineering effort, and a dedicated and motivated technical team--features in short supply in the mining industry today. However, an alternative to in-house development of frontier technologies is available to this beleagured industry through entrepreneurial, high-tech companies. These entities, with their dedicated focus toward product development, motivated and streamlined teams, high productivity and efficiency, and low costs offer a unique opportunity for large corporations to obtain high-tech products and services. These commodities are available through traditional commercial channels and an array of creative business arrangements. The latter offers notable benefits to large companies including windows on frontier technologies and mitigation of risk. Likewise, entrepreneurial companies profit through manufacturing and marketing relationships and an expanded financial base.

Jan 1, 1985

By Peter J. Borchardt, Helen M. K. Andersson, Donald A. Bruce

Grouting is a useful engineering tool for tunnels throughout the world. A wide variety of methods and materials are used, reflecting the broad range of geological, hydrogeological, and structural demands. Most tunnel grouting is conducted with cement, which produces acceptable results in appropriate conditions. However, there are cases where such grouts are not practical, but polyurethane grouts can be extremely useful. Regretfully, these grouts are frequently poorly understood, leading to improper application and therefore poor results. This paper provides a fundamental overview of their application, both used individually and in combination with cement. Case histories from Scandinavian practice are cited.

Jan 1, 2001

By M. Myers, T. Oxley

Price, lead-time, efficiency, availability, maintainability. These are all the factors involved in the selection of components for a conveyor system in a mining operation. Historically, the decision-makers do not consider all these factors together when it is time to procure the equipment needed to assemble a conveyor system. The Total Cost of Ownership approach enables an operation to attain superior efficiency and desirable maintenance practices, all while minimizing the total cost to operate and maximizing the return on investment.

Jan 1, 2003

By B. Stewart, J. R. Warneke

The productivity of underground mines has increased dramatically since the introduction of continuous miners. A variety of new hazards have developed as a result. In the spring of 2004, Mine Health and Safety Administration (MSHA) held a workshop to brainstorm ideas to decrease the number of injuries associated with continuous miners. One of the main areas of discussion at the workshop was “trailing cable-handling injuries.” The method of handling the power cables over the years has changed very little while the technology and uses of continuous miners has advanced dramatically. This paper will discuss the main ideas brainstormed at the MSHA continuous miner (CM) trailing cable handling workshop and the history and root causes of cable-handling injuries, as well as proposed ideas developed at the National Institute for Occupational Safety and Health (NIOSH) to alleviate some of the cable handling issues.

Jan 1, 2006

Anhydrite-based dam constructions, which have been implemented successfully in other geological formations, were investigated with regard to their suitability in salt mines. The laboratory investigations show that anhydrite-based building materials with suitable additives bind safely in spite of the high temperatures in salt mines which normally pre-vent hydration. The dependence of the compressive strength, swelling behavior, porosity and permeability upon the choice and ratio of binding material components and additives was determined. Based on the results of these investigations, a pilot-scale experiment was carried out at the GSF Research Mine Asse (Germany) using a mixture suitable for the prevailing conditions

Jan 1, 2004

By Francis S. Kendorski

INTRODUCTION Drift design problems in caving operations are a re¬sult of the geologic factors contributing to the overall success of the system, of the engineering factors dictated by economic and technical considerations, and of ore production practices. Combining these factors, a rational underground sup¬port system of rock reinforcement, light steel channel section or welded wire fabric, and shotcrete can be de¬signed based on rock fracturing, rock load, abutment loadings, ground movement, expected repair and desired flexibility. The design concept uses the effect achieved by restraining, reinforcing, and maintaining some of the intrinsic strength of the fractured rock mass composed of interlocked blocks of intact rock and rock fractures. Three different examples of drift support design in hypo¬thetical mines using the caving system are given. Caving is a system of underground mining where ore is extracted by means of gravity after the ore body is allowed to fail by removing support from underneath. The rock mass of the ore body fractures and flows ver¬tically downward to let gravity do as much work as pos¬sible. Caving differs from many other mining systems in that blasting is used only to initiate the rock mass failure by removing the rock supporting the ore but not to break the ore itself. The initial movement of the rock mass dur¬ing failure and the consequent crushing and grinding during the continued movement serve to reduce the ore to particles of a manageable size, with only limited sec¬ondary blasting necessary. The broken ore is extracted from the bottom of the failed rock mass through funnels of some sort pre-excavated in the rock. Ore extraction must continue or the swell of the broken rock will even¬tually fill the cavity and stop further rock mass failure and movement. The excellent general discussion on block caving in the SME Mining Engineering Handbook (Julin and Tobie, 1973) adequately covers the principles and application of this type of underground mining. Many rock mechanics aspects of block caving have been covered by others (McMahon and Kendrick, 1969; Swaisgood, et al., 1972; Mahtab and Dixon, 1975; King, 1946) and will not be reviewed further. Maintaining the stability of production drifts is one of the most troublesome problems plaguing the mine manager in a caving operation. Many factors contrib¬ute to drift support problems, and identifying the causes of instability and producing a reasonable support design are two steps toward achieving stability consistent with the mine plan. This chapter sets forth a technique for the design of support systems for production drifts in caving opera¬tions. The basic support system elements employed are rock reinforcement, welded wire fabric, and shotcrete. Recognized as contributing to the design are the factors of rock load, additional load from mining activity, rock fracture characteristics, repair expected, and flexibility. It must be emphasized that the drift must first be stabilized as for a tunnel, and the additional strengthen¬ing for mining-induced loads cannot contribute to the initial premining stabilization, or the reserve of strength is used up. MINE PLANNING The efficient mine planning engineer not only must satisfy the economic, human, and environmental aspects of his task but must also consider the mechanical con¬sequences of his plan. The problems created for the mine by placing parallel drifts too close, by crossing drifts on different levels with inadequate, if any, separa¬tion, and by installing connections and crossovers in the haulage plan without regard for the effective spans cre¬ated, are only a few of the problems a mine planning engineer can create for himself and the mine. The effect on immediately adjacent mine areas when an area is caved is important to drift design because the removal of vertical support from a rock mass causes the weight of that rock mass to be shifted elsewhere. The adjacent rock mass will carry this load and reach a new equilibrium with the applied stress. The advancing front of stress increase that results from caving (and many other mining systems) is generally called the abutment load and is the increase in stress over the gravity or tec¬tonic stress that already exists, as shown in Fig. 1. In general, the abutment load will be similar in nature to the stress change found around an opening in rock and will be taken as causing an increase in the vertical prin¬cipal stress, due to an approaching caving boundary, so that

Jan 1, 1982

By B. T. Dawson

In today's work world, constant changes are a fact of life. Downsizing and technological advances are two of the most prominent concerns for employers and employees alike. In this article, the author addresses some of the emotional consequences of these changes and offers a new, empowering perspective for coping with them.

Jan 1, 1998

By Stefan Gerl, Werner Stahl

Steam pressure filtration combines mechanical and thermal processes in one filtration device. Steam condensation at the cold layers of the filter cake, build a condensation front, which even removes the capillary water from the porous filter cake. Depending on the choice of parameters it is possible to achieve a very low residual moisture content. The influence of the parameters on the dewatering results was systematically examined on a bench-scale apparatus. This paper explains the physical fundamentals, the influence of the cake dewatering parameters, and one possible method of applying the process to a disk filter device as well.

Jan 1, 1995