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By P. J. Brown, R. W. Nice

The Thalanga Copper-Lead-Zinc Concentrator in Northern Queensland was commissioned in early 1990. The design of a flotation process for the sequential production of separate copper, lead, and zinc concentrates has always been a most formidable mineral processing challenge. In 1988-1989 during the process design phase, sized fractions of various samples were subjected to quantitative and qualitative mineral analyses. These analytical techniques are collectively known as modal analysis. Modal analysis aided in the selection of key process treatment parameters for the initial laboratory testwork on the Thalanga ore. The work also guided the flowsheet development and quantified the mineralogically imposed limitations on the separation process. This paper describes in general terms how these modal techniques were used to guide the program of laboratory flotation testwork which constituted the flowsheet design phase of this project. During these design studies, the primary grind and regrind requirements were deduced and the basic flowsheet configuration selected. Recent operating plant performance data are to illustrate the value of modal methods in addressing complex metallurgical separation problems.

Jan 1, 1995

By J. A. van Huyssteen, P. H. Radcliffe

With the profit squeeze of recent years and indeed the survival of many mines at risk due to low gold prices and declining grades, many inventive solutions have been found of increase production and decrease cost. One of these is the application of process auditing methodology which is essentially a tool to determine systematically whether a process is delivering optimally and, if not, to identify the basic causes. Then a prioritized action plan can be developed with the client. Our experience has shown that problems are seldom what they appear to be and that most processes can operate far more efficiently with relative little effort. A process auditor requires good facilitation skills to overcome initial suspicion, and for sustainable solutions client involvement is essential. Process auditing as it is being applied in Anglogold has evolved over many years to reach its current format. The lessons learned and insights gained in the process are shared here with the reader.

Jan 1, 1999

By L. L. Oriard

The author describes three case histories of fracture-control blasting demonstrations. This is a technique in which the walls of blast holes are scribed or notched in order to enhance the development of blast_induced fractures, and to control their direction. One demonstration was that of a tunneling application in a rock that was generally competent but strongly foliated, hence strongly anisotropic. P second test was conducted for perimeter blasting of a structural excavation in a massively jointed limestone. A third field test was conducted for tunneling through an old concrete structure. Increased applications are envisioned with new tool modifications being developed at the University of Maryland.

Jan 1, 1981

By Graeme J. Jameson

A form of column flotation cell is described in which the contact between the feed and the air stream is made in a mixing device at the top of a vertical downcomer. The air-liquid mixture flows downward to discharge into a shallow pool of pulp in the bottom of a short cylindrical column. The bubbles disengage and rise to the top of the column to overflow into a concentrate launder, while the tails are discharged from the bottom of the vessel. The main advantages of the device described are that the overall height of the column is reduced to about one metre (3 ft), and the column can be self-inducing with respect to the air supply. Experimental results are given from tests on a feed stream to a conventional zinc cleaner circuit. Using wash-water to reduce gangue entrainment, the column gave high concentrate grades and high recoveries.

Jan 1, 1988

By A. S. Malicsi, Vathsala Rajagopal, I. Iwasaki

Corrosion and abrasion properties of a series of chromium-containing, cast-iron balls, with Cr contents ranging from 0% to 29%, were evaluated and compared with austenitic stainless-steel and mild-steel balls. Marked ball wear tests were performed on artificial ore samples consisting of 95% quartzite, with either 5% pyrrhotite or 5% chalcopyrite, under a nitrogen or oxygen atmosphere. The electrochemical mechanism was investigated by correlating the corrosive wear with the corrosion currents obtained from potentiodynantic polarization curves under abrasion. Flotation recoveries were determined on a 95% quartzite + 5% pyrrhotite sample ground with various cast-iron ball materials under an oxygen or nitrogen atmosphere. Electrochemical results are found to be in good agreement with flotation results and with corrosive wear data obtained from marked ball wear tests.

Jan 1, 1993

By S. O. Moshier, L. S. Barron, J. C. Hower

The Hardgrove grindability test, commonly used in coal characterization, was conducted on 13 Mississippian carbonates from Kentucky, Tennessee and Illinois. The results demonstrated that the grindability increases with a decrease in the Si02/(MgCO3+CaCO3) ratio, with fine-grained and petrographically-complex stones having lower grindabilities. Also, the relationship between the Bond work index and Hardgrove grindability is significant.

Jan 1, 1993

By Z. Eisenstein, H. K. Heinz, F. M. Kuwajima

Due to its complex rheological behaviour, shotcrete induces a ground-structure interaction that differs significantly from other types of tunnel linings. For the same reason, the instrumentation of shotcrete linings presents special problems, particularly when it comes to estimating the stresses transferred to the lining during construction. The shotcrete characteristics which affect the stress distribution are initially discussed. Measurements obtained in a recent soft ground tunnel are also presented. The conclusions are aimed at introducing practical recommendations for the design of tunnels where shotcrete is used as initial and/or final support.

Jan 1, 1991

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 Charles A. Edwards, Kenneth D. Merrill

The Construction of the Northeast Extension of the Baltimore Metro involved soft ground, compressed air tunneling. During the tunneling, gasoline and dry cleaning fluid contamination were encountered. Innovative approaches and solutions were developed to address these problems. Special emphasis was on the problem of compressed air pushing gasoline vapors into surrounding communities, resulting in an extremely dangerous situation and a public relations nightmare. Guidelines and standards were established for working in this contaminated environment. Also, through a proactive approach by all parties, all claims and disputes have been resolved.

Jan 1, 1995

By D. S. Choi, D. L. McCain

INTRODUCTION Coal is forecast to be an increasingly important and economical source of energy for the future as the supply of oil and gas declines relative to overall energy demand and perhaps in absolute quantities produced. With the decline in productivity, especially in underground mining, in the early seventies coinciding with the need to produce greater quantities of coal for market, a gradual change from room-and-pillar mining to longwall mining has been taking place in the United States. Consolidation Coal Company (Consul) produces about 50 million tons of coal per year with approximately 66% being from underground mines. Most of the mines are located in the Appalachian Region in the States of Pennsylvania, West Virginia and Virginia, and in Ohio and Illinois. Coal is produced by the room-and-pillar mining method with continuous mining machines in addition to an increasing number of longwall mining faces. Continuous mining machines will continue to be used for driving longwall development entries as well as in areas where partial extraction must be practiced in order to support the overburden rock because of surface structures or in areas that cannot be subsided, or where unfavorable geologic conditions limit the application of the longwall mining methods. ROOM-AND-PILLAR MINING METHOD Some background in the room-and-pillar mining method may be helpful to provide perspective. This method has been widely practiced since the beginning of coal mining in the region. It is a flexible system because it can provide either partial or nearly complete extraction, and coal pillars can be left where needed to support surface structures or oil or gas wells or because of unfavorable geologic conditions (Choi, Dahl and McCain, 1980).

Jan 1, 1983

By Peng Yu-mei, Cao Zhi-yun, Fan Qing-en

In China, an enormous amount of Au-Ag bering calcines, residues and tailings are produced each year from various sources in mining, metallurgical and chemical industries. For a long time, these materials have been either stored up in dumps or disposed of into rivers, resulting in not only waste of resources but also severe environmental pollution. It is therefore of great significance, both from economical and public welfare points of view, to recover efficiently and make full use of the metallic values from these miscellaneous materials. In this paper the physical and chemical properties of these Au-Ag bearing calcines, leached residues and tailings are described and the current status of their utilization are briefly outlined, followed by a more detailed description of some innovative processes now in practice. Lastly, the potential prospects of gold and silver recovery from these materials in China, particularly in the Hunan province, are envisaged.

Jan 1, 1998

By P. Somasundaran

Beneficiation by froth flotation, which exploits the difference in surface properties of minerals, has been a promising method for coal cleaning. However, dissolved mineral species present in coal flotation systems can interact with particles and other species leading to drastic effects on flotation. Particularly, precipitation or adsorption of such species on the particles can alter their surface properties and thus influence the efficiency of coal cleaning. In this work, the bulk and surface precipitation of the dissolved mineral species present in Pittsburgh No. 8 coal was investigated under controlled experimental conditions. Changes in the surface properties of coal due to the precipitation were monitored by following zeta potential. Solution potential data were used to elucidate the mechanism of the precipitation. The effect of the precipitation of the dissolved species on the floatability of coal was found to be marked.

Jan 1, 1995

By Richard L. Coleman

El trabajo de ensayo metalúrgico para desarrollar un flujograma es el que ahora describimos, comenzando con una información experimentada requerida en todo momento hasta llegar a un esquema final de flujo de un proceso. Tanto las pruebas de laboratorio como de planta piloto son revisadas adecuadamente sobre las experiencias anteriores.

Jan 1, 1982

By C. J. Konya

When blasts are designed, the assumption is made that all blastholes release near ideal energy. In many types of mining operations, some blastholes release very little useful energy. These blastholes will be called malfunctioning blastholes. Recent studies indicate that on many types of blasting applications, 30 percent of blastholes are malfunctioning. This malfunctioning routinely occurs on the operation and is not an unusual occurrence. This paper will discuss the cause of malfunctioning blastholes and methods to minimize the detrimental effect on both safety and costs.

Jan 1, 1988

By Nicholas Kyriazia, John P. Shubilla

A performance study of oxygen self-rescuers of varying durations from the United States and other countries was undertaken as an assessment of present worldwide technology. The apparatus were tested on a Breathing and Metabolic Simulator in the Life Support laboratories of the Bureau's Pitts- burgh Research Center. Parameters monitored during the testing were inhaled levels of C02, 02, inhaled gas temperature, and breathing resistance. The metabolic demand placed on the apparatus represented the average demand of the 50th percentile miner performing a 60-min man-test 4, as described in 30 CFR 11H. Results presented include apparatus service life and subjective comments as well as averages and peaks of monitored parameters.

Jan 1, 1986

By S. K. Mukherjee, A. W. Laurito, M. M. Singh, N. I. Jayaraman

This paper describes the application of foam to control respirable dust in a double-drum longwall mining section. The feasibility of injecting an adequate quantity of foam through the shearer drum was initially established in the laboratory. Thereafter, underground testing of the foam system to determine its effectiveness on an active operating longwall was conducted in a mine in West Virginia. The foam system proved superior to the water spray system. The details of the laboratory and field investigations, the results obtained, and the degree of acceptance of this system by the mining company are discussed in this paper.

Jan 1, 1987

By D. Denton, C. Peppin, D. Tesarik, D. Bayer, J. B. Seymour

Hecla Mining Company and NIOSH cooperated in a study to document the safety of rock support supplied by reinforced cemented paste backfill at the Lucky Friday Mine. Data are presented on backfill modulus values from laboratory tests and compared with modulus values from in-mine wall closure on the backfill. It is theorized that a compressive zone is created in the backfill between the upper and lower bearing plates on the reinforcing bolts, and that the backfill remains stable as long as the compressive zones from adjacent bolts overlap.

Jan 1, 2001

By Leonard Harris

Good morning ladies and gentlemen. I would like to thank Hans von Michaelis for inviting me here today to talk to you on the subject of "How to Reduce Capital and Operating Costs at Heap Leaching Projects". The comments I have to offer are based on my experiences in gold heap leaching by Newmont Gold Company in Nevada, by Newcrest in Western Australia (formerly Newmont Australia), by Minera Yanacocha in Peru, by Penmont in Mexico, by Z­Mont in Uzbekistan, by the Hochschild Group in Peru and expe­riences in copper heap leaching by Magma Copper Company in Arizona and as a consultant on several other smaller projects worldwide. These comments are a mixture of technology, ideology, philos­ophy, strategy, logic and opinions and might be looked at by many of you as "one man's view". I like to look at them as "a view from the bridge". Let me add that it doesn't bother me that you may not agree with my comments and that I would be interested in your comments or criticisms at the end of this presentation. I don't intend to discuss the details of the mineralogical and metallurgical test work. I will assume, for this talk, that the test work has been conducted very carefully and that the ore in ques­tion has been determined to be heap or dump leachable. Let's begin with a couple of don'ts! ! First, "don't build the mill until you have a mine". This might sound to many of you as fundamental but believe me it continues to happen. The minable reserves should be well known and established as being economical to mine and leach. NPVs, ROis and IRRs are fine if you can be sure of the gold price you use in your calculations. The best method is to carefully estimate the capital cost and, most importantly, the operating cost per ounce of gold recovered which should include the repayment of the borrowed capital and the interest thereon. For example, if the operating cost under these conditions is $200 per ounce, you have a project. If it is $400 per ounce, walk away f om it. Incidentally, the same prin­ciple can be applied to projects involving other metals such as silver, copper, lead, zinc, etc. The second don't is - "don't be sheep". Don't climb on the bandwagon with respect to design and operation because every­one else does it a certain way. Keep an open mind, be versatile, look for change, look for every possible innovation for reducing capital and operating costs. Beware of those who will tell you "we tried that it won't work" or "it's too expensive" or "that's a crazy idea" , <' ''what do you know about mining - you are a metallurgist aren't you" or "what do you know about metallurgy - you are a miner aren't you" or "only geologists can handle this issue". Be careful about pigeon-holing people according to their basic degree and experience. In these days of low metal prices, we need to consider everybody's ideas, as crazy as some of them might seem.

Jan 1, 1998

By R. F. Holub, P. J. Dallimore

Basic to solving the problem of the role of radon transport on radon concentrations in mines is to establish whether it occurs primarily as diffusion and forced flow through porous rock or through fissures in the rock. The laboratory experiments performed involved measurements of diffusion and emanation coefficients, porosity and permeability of representative rock samples. Significant differences have been found when comparing the results of the laboratory permeability determinations to those of the mine determinations. Considerations of underlying principles, however, suggest that the diffusion and emanation coefficients are the same in laboratory and mine. It was also found that moisture content plays a dominant role in radon transport through rock. Using these concepts and findings, some conclusions about the radon concentrations in mines have been drawn.

Jan 1, 1981

By Bernardo Portillo, Alejandro Perez, Daniel Norrgran, Joseph Wernham

High gradient permanent magnetic separators (termed "Ferrous Wheel") are described as used to recover the iron bearing minerals from mill tailings at the Grupo Acerero del Norte&apos;s Hercules iron mines in Coahuila, Mexico. The pilot scale test work as well as the "in-plant" test work provided the basis for a 385 MTPH plant expansion to be commissioned late in 1995. Approximately 6 million metric tons of flotation tailings averaging 50 percent iron, mostly as hematite, are contained in two separate ponds. The tailings are relatively fine at 93 percent -200 mesh and 72 percent -500 mesh. After testing various recovery methods, a high gradient permanent magnetic separator was selected to produce a preconcentrate prior to flotation. The separator uses a flux converging matrix to generate high gradient magnetic fields and capture the hematite. The advantage of the Ferrous Wheel high gradient permanent magnetic separator is the use of permanent magnets as opposed to electro-magnets. Further the vertical rotating ring is much more conducive to matrix cleaning as opposed to the conventional horizontal ring separators. This feature also allows the use of a wide range of matrix materials to achieve the optimum metallurgical response

Jan 1, 1995