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By F. H. Deist, J. P. E. Morris, E. Georgiadis

For some years the Collieries Research Laboratory of the Chamber of Mines of South Africa has been engaged in the development and application of computer programmes to aid in the solution of rock mechanics problems. It is the purpose of this paper to introduce some of the programmes having general applicability. A system capable of predicting stresses and displacements induced by large-scale tabular excavations is discussed. A finite element programme especially designed for handling layered continuum problems, and which is being used extensively has been supplemented by an automatic mesh generation facility that reduces problem preparation times considerably. Some typical applications of these programmes are described. An entirely new approach, potentially capable of performing linear three-dimensional continuum analysis at practical cost is introduced.

By Theo Lehner

Turning matte into anodes continues to be an area to watch: for visitors to see pyrometallurgy in action; for metallurgists to keep up with modern smelting furnaces and ever increasing production rates; for management to remain profitable using more tools than taught in school; and for environmentalists to detect the last small clouds from the ever cleaner smelter. Current converting practices have been screened and analyzed, and today, converting and casting is a modern industry. An impressive, though typical learning curve of converter productivity may be detected. Local conditions such as availability and type of raw materials, products extracted, cost factors, etc., have stimulated the development of add-ons or even alternatives to the still dominant method of converting by Peirce-Smith technology. Turning blister copper into anodes follows a similar path, namely increased productivity and improved quality. We dare to predict that development will continue.

Jan 1, 2005

By P M. Outhwaite

Everyone present today is especially aware of the need for minerals in this society of ours. The words 'especially aware' were deliberately chosen because this is a meeting of the NZ Branch of The Australasian Institute of Mining and Metallurgy not a dilettante group such as some of our critics. Members of the Australasian Institute of Mining and Metallurgy knew that our great farming industry, our shelter, our transport and our energy supply, are largely dependent on a flow of minerals into this country despite the presence of large coal and natural gas reserves. Flow in was said because New Zealand imports most of its mineral requirements with all the consequential strategic and economic disadvantages. If the above statements are accepted by this gathering it would be a premise fairly stated that New Zealand has a great need to discover and develop minerals.

Jan 1, 1976

By M. A. Keogh

This paper reviews the physical properties that make low-density polyethylene the most practical and economical material for launder• fabrication in the majority of mine and mill applications. The basic design features and use of other launcher• materials are also discussed.

Jan 1, 1976

Mines in the Lake Macquarie region of New South Wales, Australia, are faced with the dilemma of having to introduce longwall mining techniques at a time when increasingly large areas of the surface are being used for urban development. Increasing pressures on safety, costs and productivity performance dictate that longwall mining is the method for the future. Construction of surface structures is controlled by a statutory body known as the Mine Subsidence Board (MSB). All surface structures have to be designed to MSB criteria. All mining plans involving secondary excavation also have to be submitted to the MSB for approval. The Board acts as risk assessor in evaluating acceptable levels of surface subsidence vs. the value of the coal resource. Surface repairs are paid for by a levy on all coal producers.

Jan 1, 1995

By Armando Alatorre

The Republic of México is the world's largest producer of celestite/strontium carbonate and natural sodium sulfate. It is also a significant producer of flourspar, barite, graphite, sulfur, feldspar, salt and gypsum. New production may be brought on stream for borates, wollastonite, garnet, calcium carbonate and others. The country covers a geographic area of approximately 2 million square kilometers (760,000 square miles), and is divided into seven geological/geomorphological provinces. Less than 20 percent has been explored in detail for either nonmetallic or metallic minerals. This leaves large areas available for the discovery of world-class industrial mineral deposits. In addition to new deposits of those minerals currently being produced, there is exploration and development potential for borates, magnesite, rare earths, nepheline syenite, heavy mineral sands and numerous others.

Jan 1, 1995

By A. Zangooi, J. A. Finch

"A frother analysis technique based on the formation of a colored solution with UV-VIS absorbance proportional to frother concentration over a certain range has been developed. The calculation of concentration requires the comparison of the sample absorbance at a selected wavelength with a linear calibration (frother concentration vs. absorbance) constructed with values collected from solutions of known concentration (standards) at the same wavelength. It has been found that concentration ranges for preparation of standards can vary widely. An integration of our experiences into a databank can offer some guidance on the selection of standard concentrations. The databank includes results from the analysis of 37 chemical reagents, commercial frothers, and natural oils used in research work or at industrial sites. Grouping frothers by similar chemical structure or origin provides a good basis for selecting the standards to approach the maximum absorbance range for the spectrophotometer in use.INTRODUCTIONA technique to determine frother concentration on samples of industrial milling streams based on formation of a colored solution with UV-VIS absorbance proportional to frother concentration has been developed. The concentration is determined by comparison of its absorbance, at some selected wavelength, with those obtained by processing a series of solutions of known concentration (standards), at the same wavelength. It is desirable to have linear calibration (frother concentration vs. absorbance) over the widest concentration range. The upper concentration can be restricted by the instrument, as there is a maximum detectable absorbance (minimum transmittance), which can be reliably sensed by the UV-VIS detector (in most cases maximum absorbance is 3)."

Jan 1, 2016

By E. C. Harder

Few mineral deposits have in recent years attracted such general and widespread attention as the Brazilian iron-ore depositis…

Jan 1, 1915

By C. E. Mendenhall

FOR the purpose in hand, pyrometry may be taken to include all temperature measurements from, say, 200° C. to the highest attainable, especially when considered from the technical or applied side. It will be convenient first to consider the entire content of a course of study grouped under the headings of the various methods of measurement, which are quite distinct in principle and involve different equipment. Brief suggestions will be given under each heading, and the summary will be followed by comments on the purpose of such a course and methods of conducting it. 1. Expansion and pressure methods: mercury thermometers (glass and quartz), liquid, gas, and vapor-pressure thermometers, especially recording instruments. Especial attention should be given to the limitations of these methods, which, particularly in high-temperature mercury thermometry, are often overlooked. Range approximately to 700° C. 2. Resistance thermometers: both bridge and potentiometer methods, of indicating and recording. Calibration; lead compensation; design of thermometers for special purposes. Range to 1200° C. 3. Thermoelectric pyrometers: potentiometer and deflection methods indicating and recording. Calibration, leakage errors, contamination errors, base and noble couples. Range to 1500° C. 4. Total radiation methods: thermoelectric, resistance, and expansion indicators, mirror and lens collectors, calibration, permanence of characteristics, absorption errors. Range, to highest attainable temperatures. Methods of producing perfect radiators-true, and virtual or "black body" temperatures. 5. Partial radiation methods: absorption and spectroscopic methods of getting partial radiation, various comparison sources, polarization, electric, sector, and absorption methods of controlling intensity (Morse, Lummer, and Wanner types). Calibration, permanence of calibration, absorption errors. Methods of producing perfect radiators -improvised methods; true, and virtual or black-body temperatures.

Jan 9, 1919

By Gerald V. Jergensen, Edward J. Samuel

Slurry system are the principal method for storage and transportation of solids within and between concentration operations In a mineral processing plant. A slurry 1s a mixture of solid particles In water, or a chemical solution, that behaves like a liquid. The design of slurry transportation systems is generally analagous to pumping and piping water, but with a few notable exceptions: • The interaction of particle on particle affects slurry transport. • Particles often interact with the fluid, particularly when chemicals have been added to the system. • Particles have a frustrating tendency to settle from the slurry suspension, especially into locations not considered In the design. • Solids have an affinity for wetted surf aces and tend to wear them away. Slurry transportation systems Include a number of separate components, each requiring special design considerations. A systematic evaluation of each component of a slurry transfer system will help overlooking the small details that could cause operational headaches. Most slurry transport systems include: • A receiving sump or tank that provides for mixing and/or momentary storage of slurry. • A driving force.. by a pump, atmospheric pressure or gravity. • A suitable conduit for transportation.. pipes or launders. • A delivery objective.. another sump or process vessel, or distribution system to several process points. • A control strategy and design to regulate the transfer operation. The design of the slurry transportation system normally evolves through the following steps: • Finalizing the process flowsheet and establishing the weights and volumes to be handled. • Identifying and characterizing the various process fluids and slurries. • Defining critical and minimum transport velocities of fluids. • Selecting a pipe diameter (or dimensions and gradient) and

Jan 1, 1986

By Richard L. Stein

INTRODUCTION Increasing a miner's chance of surviving a disaster requires advance planning for emergencies, adequate training of personnel, and the provision of proper survival equipment. It is extremely important that fires and toxic gases be detected early, and that warning systems such as stench, audible and visual alarms, and communications systems be provided to allow timely escape. However, situations do occur where timely warning is not provided and immediate escape is not possible, regardless of the precautions that are taken. Under such circumstances, a combination of new per¬sonal protective devices and old techniques can provide protection that is adequate to save a miner's life. SELF-RESCUE EQUIPMENT Self-rescuers are devices which provide a short-term supply of respirable air under the potentially lethal con¬ditions following a mine disaster. Functioning either as filtration devices for the elimination of carbon monoxide (CO) or as oxygen supplies, self-rescuers allow an endangered miner a limited amount of time in which to effect an escape or reach a place of temporary safety. Carbon-Monoxide Self-Rescuers For almost 50 years, filtration self-rescuers have protected miners' lives following explosions or fires. Designed to eliminate carbon monoxide from inhaled air, the first of these devices was approved in the 1920s and has evolved into the two units that are approved today-the Mine Safety Appliance (MSA) W-65 and the Draeger 810. Both of these units rely on the cata¬lytic conversion of very toxic carbon monoxide to rela¬tively safe levels of carbon dioxide (CO,). As shown in Figs. 1 and 2, both of these filtration self-rescuers operate in the same manner. On inhalation, the mine air passes through both coarse and fine filters that remove the dust, preventing the dust from coating the chemical beds or entering the miner's mouth. The air then passes over a drying agent that removes water vapor; this is required to prevent the water vapor from poisoning the catalyst. Subsequently, the dried air passes over the Hopcalite catalyst, where carbon monoxide is converted to carbon dioxide. Then, the air passes through a heat exchanger that reduces the temperature of the inhaled air. Finally, the air is inhaled by the user. Air exhaled by the user passes through the heat ex¬changer and exits the device through an expiratory valve. Both units of this type are subject to certain limita¬tions: 1) The units do not protect the user against oxygen¬deficient air; when air is inhaled through this type of self-rescuer, the device only removes the carbon mon¬oxide. If the mine air contains less than 15% oxygen, anoxia is inevitable. Symptoms of anoxia include dizzi¬ness, shortness of breath, quickened pulse, and deeper and more rapid respiration while the victim is at rest. During heavy exertion such as would be expected dur¬ ing escape efforts, a 15% oxygen level can cause loss of consciousness. 2) The units do not protect against excessive levels of carbon dioxide. Available data on carbon monoxide and carbon dioxide concentrations following explosions or fires are limited, but there are indications that the carbon monoxide concentration can rise to 2% and the carbon dioxide concentration can reach 5 or 6% of the mine air (by volume). In some situations, the in¬haled air could contain up to 6 or 7% carbon dioxide. At a carbon dioxide concentration higher than 2%, breathing patterns can be affected adversely. At a con¬centration of 6 or 7%, the effects include severe respira¬tory distress, with unconsciousness resulting from exer¬tion such as that needed for escape activities. 3) The units do not protect against high inhalation temperatures. The catalytic oxidation of carbon mon¬oxide to carbon dioxide is an exothermic reaction that evolves a large amount of heat. As the carbon monoxide concentration increases, the temperature of the inhaled air also increases. Available data show that above 1.5% carbon monoxide, the air inhaled through some self¬rescuers can be as high as 90°C (194°F). At those

Jan 1, 1982

By F. Robert Hollo

Programmable controllers have achieved remarkable acceptance over the relatively few years since their introduction. They provide some unique advantages over conventional relay and solid-state logic, which they often replace. Programmable controllers are discussed in both conceptual and functional terms, followed by an exploration of their applicability to material handling tasks with particular emphasis on conveyor systems.

Jan 1, 1973

By P. Corser

Operational and geotechnical constraints on mining within steeply dipping deposits and historic landslide areas, which are characteristic of subarctic coal deposits in Alaska, will be discussed. The current plan for mining through these areas will be presented, as well as an alternative plan for minimizing the adverse effects of mining through an historic landslide area.

Jan 1, 1988

By John J. Vieaux

Allowable loads on Dynamically-Cast-In-Place Piles (the Franki type) can be correlated with N values from the Standard Penetration Test. Using a constant developed by Nordlund, a conservative value for load-carrying capability of a DCIP pile is developed. The DCIP pile and method of installation is briefly described.

Jan 1, 1984

MR. DICKINSON: There is an increase of dust in machine loading, especially with the McKinlay loading and cutting machine which was extremely dusty. MR. FORRESTER: Declared more dust must be expected because when loading by machinery, the coal is shot harder in order to make it easier for the machine to pick it up. He believes however, that there was less hazard because of the closer supervision possible by reason of the concentration of operation. MR. McAULIFFE: Machine loading more dusty than hand loading. D. HARRINGTON: The hazard is greatly increased by modern methods of loading. Not only do the methods increase the quantity of dust, but they also increase the rapidity of mining and the increased quantity of coal broken down causes large quantities of gas to be released. The number of motors on loading machines and conveyors add to the hazard. No more dangerous places can be found for such motors than at the working face where there is excessive quantities of pure coal dust and where there is more gas than along any other point. Regarding Mr. Herres remarks that the machine loading was safer on account of the concentration and possibility of close supervision, Mr. Harrington said he believed concentration likely to prove a source of danger rather than its preventive. At Dolomite, Alabama, a number of men had assembled, and as a result what was a relatively small explosion killed a large number of men. Concentration is not without its dangers to mine operations. MR. McAULIFFE: These arguments do not appeal to me. Few places are better sprinkled than the working places in a machine loading mine. There is. more effective supervision, and there can be more ventilation. I believe machine loading will increase safety by that very concentration that Mr. Harrington deplores.

Jan 1, 1925

By S. Selmer-Olsen

New trends and developments in the production of ferro-silicon, ferro-manganese and ferro-chrome alloys are discussed, with emphasis on the general trend to the adoption of large production units. Problems which arise, both of a metallurgical and an electrical nature, due to the use of large electric furnaces, are outlined with specific reference to the limitations imposed by the power carrying capacity of Soderberg electrodes, the furnace resistance and the furnace reactance. The implications of combining high resistance within the furnace with good metallurgical operating conditions are illustrated by considering the production of ferro-silicon and ferro-manganese. The possibility of replacing electric furnaces used for ferro-manganese production, by large low shaft blast furnaces using oxygen enriched blast, is mentioned. The continued use of small electric arc furnaces for ferro-chrome production is also mentioned, and is ascribed to lack of ore suitable for treatment in large furnaces. Agglomeration of chromite ores appears to be a possible answer to this problem.

By E. P. Pfleider

DIAMOND drill research work was initiated at the School of Mines, University of Minnesota, in late 1949. The Drilling Symposium held in Duluth that spring highlighted the problem of high cost and core recovery and the need for controlled testing. An advisory committee made up of informed representatives of both mining companies and drilling companies was formed to suggest and advise on a program of drill research. A Hy-Mac hydraulic drill unit, see Fig. 1, especially designed for experimental testing, was obtained for this work by the School of Mines through the courtesy of the Carboloy Co. It is an extremely flexible unit, capable of exerting a forward thrust of about 1750 lb and turning at speeds from 650 to 2200 rpm. The feed arrangement is so designed that the advance can be set either at a constant rate or permitted to vary at a fixed pressure, see Fig. 2. The

Jan 1, 1952

By Lauren A. Wright

General prosperity marked the industrial mineral industries of the U.S. and Canada in 1962. For most commodities, production and sales exceeded 1961 figures, and for several commodities, all-time production peaks were reached. Many millions of dollars were spent on exploration for and development of industrial mineral deposits, construction of new plant facilities, and expansion and modernization of existing plants. This generally satisfactory state is attributable mostly to a continuing high rate of building and heavy construction. However, for large segments of the industrial mineral field, 1962 was a year of increasingly severe competition and of problems, either existing or potential, of overproduction and overcapacity. Such problems are of particular concern to the asbestos, cement, potash and sulfur industries. As in years past, the trend continued toward larger-scale operations to permit lower production costs per unit of material mined, toward more stringent quality controls and toward marketing methods that provide greater efficiency and customer convenience.

Jan 2, 1963

By R. G. Robins, O. J. Kwok

The application of chemical thermodynamic theory to high temperature aqueous systems is discussed as a basis for the explanation of thermal precipitation. The derivation of high temperature potential/ pH diagrams is briefly outlined in order to show a temperature/pH relationship for hydrolytic precipitation, which is an effect that is caused simply by heating an aqueous solution. Various examples of thermal precipitation are given, with particular reference to separation of metal values from leach solutions. Metal sulphate solutions are shown to precipitate basic sulphates, hydrated sulphates , oxides, hydroxides, and oxydroxides of the metal depending largely on the pH, the concentration of metal ion, and the concentration of sulphate or bisulphate. The CuS04-H2S04-H20 system is treated in some detail, and the separation of copper from other metal ions is investigated. Other separations involving Fe, Ni, Zn, Cd, and Cr are considered. Other advantages of thermal precipitation, such as the formation of high purity, large particle size and easily filterable materials, are presented. The kinetics of thermal precipitation are also briefly examined.

Jan 1, 1973

By J. R. Perumareddi, V. S. Sastri, M. Elboujdaini

Economics of corrosion, the corrosion modes and causes, corrosion control methods to combat corrosion, along with a summary of issues and their implementation in the aerospace industry are briefly discussed.

Jan 1, 2004