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By Simon D. Strauss

The recession that began in late 1980 has proved to be not only prolonged and severe, but in certain ways unique in its effect on the mineral industries among the periods of economic slowdown experienced in the Western world since the end of World War II. This time almost all minerals have been affected. In previous business turndowns, by contrast, some mineral sectors have with-stood economic adversity well. They experienced little or no adverse effect-thanks either to a strong secular expansion in the markets for their particular product or to specific factors that caused demand to be well maintained. For example, aluminum, molybdenum, and nickel are three metals that enjoyed extraordinary growth in applications during the years 1946-1973. These metals were little affected during the recessions that occurred in that era. Similarly, coal did not suffer a pronounced drop in sales in the 1974-75 turndown because, with the price of oil rising sharply, a switch away from oil and back to coal was clearly indicated for some energy-intensive applications. Oil itself was largely impervious to the ups and downs of the business cycle until very recently. And the precious metals, gold and silver, have often been regarded as benefiting from reduced economic activity because labor becomes more available, productivity rises, and operating costs diminish. In the current recession, however, no major mineral has escaped the broad trend. The secular growth factors that were previously so evident for aluminum, molybdenum, and nickel have disappeared, at least temporarily. The stable pricing behavior that previously characterized all three of these commodities has been replaced by extreme price weakness and apparent inability of the major producers to continue their roles as market leaders. Coal and oil both have suffered from a sharp drop in energy requirements. There are those who now anticipate a collapse of the market control over oil prices so clearly exercised by OPEC since 1973. If oil prices are no longer effectively controlled by the governments of the exporting countries, then coal prices are also certain to be affected. And the combination of high interest rates, tight money, and a change in public perceptions of precious metals put the skid under gold and silver quotations in 1981 and early 1982. Although inflation has been viewed as the scourge of most Western countries ever since the oil crises of 1973-74, prices-in constant dollars-of most minerals have not risen. On the contrary, with the exception of the precious metals and oil, for most minerals the prices that prevailed at the end of 1982 were close to the levels of the Great Depression of the 1930s in constant dollar terms. Table 1 compares prices for copper, lead, zinc, and aluminum at the end of 1982 with the average prices in 1934, stated in constant 1967 dollars. This emphasis on prices for mineral commodities reflects the fact that profits of mining enterprises vary directly with the level of prices. Manufacturing and retailing enterprises march to a different tune. They establish sales prices based on costs. Their profits tend to vary with volume. Commodities are for all practical purposes fungible, that is the advantages of known brands in marketing manufactured goods have little application in a commodity market. Thus the individual seller of minerals is unable to establish his sales prices. Except where a monopoly is present, he must sell at the going market. His option is to abstain from selling if he finds the price unremunerative. In past recessions, some mineral producers chose to do precisely that-either accumulating a substantial share of their output in inventory or, in prolonged downturns, abstaining from production. During the current recession, however, private-sector mining companies did not have the option of accumulating inventories to any great extent. Capital costs for new mineral projects or for expansion of existing facilities have escalated at an alarming rate since the early 1970s. Added to this has been the heavy cost of installing pollution control or safety equipment to comply with the regulations adopted in most industrialized countries (and particularly the United States) since 1968. The consequence has been that the financial position of most major mineral enterprises in mid-1980 was already strained. To finance increased inventories meant incurring additional funded debt at high interest costs, thus impairing the concern's credit rating. Management Choices Private-sector managements have had to face up to the alternative of either continuing to produce at an unchanged rate and marketing output at unremunerative prices or reducing output. The latter has meant either operating at a curtailed rate, with con-

Jan 3, 1983

By M. R. Rosen

A technique is presented for simple characterization of the performance of flocculents in various mining applications. The method utilizes three key parameters obtained from raw settling data and combines them into a single athematical parameter called the desirability coefficient. The first two parameters are the timesrequired for the slurry-supernatant interface -to fall to two selected fractions of the starting height, and the third is the clarity of the supernatant liquid. The relative values of the three parameters may be assigned different weights in order to make them correspond with laboratory and field performance requirements of a particular industry. Provision is also made of an, internal comparison of test flocculant data with that of a control.

Jan 1, 1980

By Christophe Bragard, Marte Gutierrez, Haotian Zheng, Michael Mooney

This paper proposes a framework for applying surrogate-based approaches to evaluate SEM construction, which can both benefit the uncertainty analysis in the design stage and real-time calibration during the construction process. The performances of four surrogate modeling approaches, namely back-propagation neural network (BPNN), support vector regression (SVR), random forest (RF), and polynomial chaos expansions combined with Kriging (PCK), were evaluated and compared. A variance-based global sensitivity analysis (GSA) was performed on the surrogate predictor to quantify the impacts of geotechnical parameters on the deformation responses induced by SEM tunneling. The Regional Connector Crossover Cavern project constructed in Downtown Los Angeles was set as the benchmark problem to demonstrate the efficiency and reliability of the proposed procedure.

Jun 13, 2021

By R. L. Bleifuss

The object of this study was to evaluate the oxidized taconites of the western Mesabi iron range and to establish a correlation between the various basic taconite types and their concentratability. This study was made at the Mines Experiment Station of the University of Minnesota under the sponsorship of the Great Northern Railway Company. The initial work included a study of the original mineralogical and stratigraphic facies of the fresh taconite and traced the oxidation and leaching patterns developed during the conversion of this material to oxidized taconite. Subsequent studies have extended this work to include the semi- taconites and also the wash and heavy media ore types widely developed in the area. Each basic, original mineralogical facies or taconite type produces during alteration an equivalent secondary oxidized facies which has a unique mineralogical composition and texture. These control the concentratability of the oxidized taconites. Actually the influence of the original mineralogical composition of the iron formation extends even further and determines whether the most likely product of oxidation and leaching will be a wash ore or a heavy media ore and even to the direct shipping ores where the ratio of hematite to goethite is largely determined by the original taconite type.

Jan 1, 1964

By Donald J. Worth

When Eugene Bailey asked me to contribute to this session on "Canadian exploration - 1976", it took a little coaxing before he got me to agree. My immediate reaction was, what could i say about Canadian exploration that already had not been said a hundred times in the past few years; secondly, why include a banking person in such a discussion? Everyone knows banks only come into the picture after the discovery has been made and feasibility well established and validated. Rather than wrestle with these misgivings, I decided to take the easy way out and go on blind faith in Eugene - that is, he asked me so he must think that I could come up with some useful thoughts and at least touch upon some of the pros and cons of exploration in Canada. The object of the whole exploration exercise is to Find economic deposits, once they are found, one cannot really move them elsewhere to mine them. It follows, therefore, that we should really be speaking about the pros and cons of mining In Canada and my treatise will eventually lean in this direction. In any event and before getting down to the pros and cons, let us take a quick look at the history of mineral resource development in our country since the end of world war II. At that time, we were producing well under one billion dollars worth of mineral products including hydrocarbons.

Jan 1, 1976

By Laurent Rus, Bakar Amara, Jean Habimana

The La Fontaine Tunnel in Montreal, Quebec is currently undergoing major structural rehabilitation work and systems upgrade work to comply with current codes, standards and best practices in fire life safety and to extend its lifespan of this 55-year-old immersed tube tunnel for at least another 40 years. The paper discusses design consideration of ongoing works that include structural analyses to evaluate repair strategies for the post-tensioned reinforced caissons, the scheme to repair two leaky joints between caissons, the design of passive fire protection that involved in situ and real scale laboratory tests, and other tunnel systems upgrades.

Jun 13, 2023

By Dai Wang

Stoppings are necessary ventilation control devices for effective air distribution underground. However, one of the major problems underground mining has is that every stopping is a potential leaking source. Since air always flows from a point of high pressure to one of lower pressure, and the total pressure at every point in intake airways is higher than that in the return airways, air will always tend to leak from intake to return (Tien, 1996). In many mines, less than half of the air entering the mine actually gets to the working areas; the rest of it simply short-circuits directly to return airways through leaky stoppings instead (Timko and Thimons, 1983). Leakage through a stopping occurs because of pressure drops across the stopping and available leaky path in stoppings. Empirical equation has been widely used to characterize the relation the amount of leakage and variables that affect leakage. However the use of this equation requires accurate information for constants which are not always readily available. It is the attempt of this paper to derive an equation similar to the Atkinson Equation that can readily be applied to characterize pressure-leakage relationship for any given stopping.

Jan 1, 1998

By J. A. Botín

Mining investment decisions are difficult since decision analysis is often based on scarce information. The sources of uncertainty in large mining investment projects are particularly numerous and are present in all evaluation stages. Hence the feasibility decision for projects of this nature will largely depend on how well these sources of uncertainty are managed to achieve bankable risk levels. The risk associated to the construction stages of a mining project is particularly difficult to quantify, mainly because the large number of variables affecting constructive yields, and the complex interactions among constructive resources. This investigation focuses on developing quantitative simulation models and tools to increase the value of a mining project by means of an optimization of the preproduction equipment fleet. The models were validated through their application in the Chuquicamata Underground Mining Project.

Feb 23, 2014

By V. S. Tadsen

Today, man is able to probe space because of technological advancements including the ability to control certain combustion reactions very precisely. The recent adjustment of the attitude of Skylab by radio command from earth is an excellent example of such control. It is strange, and indeed unfortunate, that very little is known about the mechanism of combustion of pulverized coal, the primary fuel for rotary kilns. The selection of a coal for direct pulverized firing of a rotary lime kiln may be determined by trial and error, persistence of sales personnel, proximate analyses, grindability, or apparent BTU cost. Occasionally, the only question asked is, "How much lime will it make?" To study the behavior of a particle of coal in the combustion stream of a rotary kiln is most difficult. We must, therefore, discuss the general mechanism of combustion of pulverized coal, and relate this mechanism to the selection of a proper coal for a rotary kiln. The classic three T's -time, temperature, turbulence -must be enlarged upon for a better understanding of the problem. Pulverized coal occupies only 0.01 per cent of the volume of air required for its combustion. This mixture behaves like a gas and the general laws governing the movement of solid particles in gasses are in effect. The differential velocity between air and coal particles depends on forced and natural convection, diffusion, and the length of time each particle is in the combustion space. As a particle of coal absorbs heat from its surroundings, it begins to give off volatiles". These gasses ignite as their kindling temperature is reached, and burn readily because of the excess oxygen immediately available. Combustion proceeds at this stage by the outward diffusion of gas from the coal particle into the surrounding oxygen-rich envelope. We could say combustion at this stage represents a small coal particle surrounded by an envelope of volatiles burning at their point of contact with sufficient oxygen. This release or expulsion of gasses from the coal may result in exfoliation or disintegration of the coal particle. If this occurs, and it is desirable that it should, it will accelerate the final stages of combustion. The escape of volatile material from the particle of coal and its subsequent combustion will cause increased turbulence around that individual particle. Ignition is maintained by radiation from gasses and solids in the combustion system, and most importantly, re-radiation from the kiln refractories and the process load.

Jan 1, 1978

By James C. Gilliand

Leo-potpourri, was selected as the title to this paper for several reasons. First, it is a fascinating word--not looking like it sounds or sounding like it looks. It also allows for a great degree of flexibility in designing a presentation around it. Further, it has become popular to use this eco hyphen something pattern. We hear of eco-mania, eco-hysteria and the like. Lastly, in this era of intense environmental concern, two of the principle elements on which the integrity of our efforts must be equated are ecology and economics. Accordingly, the term "Eco-potpourris" allows me to roam at will through the great number of considerations that make up this environmental issue. Whereas only a few years ago the subject of environment and environmental control had low visibility with the public, today it competes as the focus of attention with the many other popular social issues of our time. The program content here at this meeting, for example, is liberally represented by papers dealing with one or more aspects of environmental concern. If one would look at the 1964 program, in contrast, I would expect that no more than possibly one or two papers covered this subject and even then that those papers dealt principally with the environmental aspect of occupational health. It is gratifying that the program at this meeting demonstrates a serious awareness to a broad spectrum of environmental concerns. It would be a mistake, of course, to believe that this clamor for a quality environment is a "flash in the pan" that will soon subside. The general public has been thoroughly aroused and even frightened into

Jan 1, 1972

By Robert R. Brandom

The Boss-Bixby deposit is one of several iron deposits that occur in the Precambrian igneous rocks of southeastern Missouri. It differs, however, from all of those deposits by its significant contents of copper, cobalt, and titanium, and its close relationship with a basic igneous intrusion. Ore microscopic study of selected drill core samples has shown that the hypogene ore minerals are magnetite, hematite, chalcopyrite, bornite, covellite, ilmenite, rutile, sphalerite, cobaltian pyrite, carrollite, scheelite, and wolframite. Subsequent partial oxidation has formed martite, pseudobrookite, and anatase. Textural evidence indicates that two stages of iron and iron-titanium oxide formation were followed by the deposition of the copper-iron sulfide minerals and carrollite.

Jan 1, 1985

By D. Bleazard

Barrick Goldstrike Mines, Inc. is actively involved in improving the reliability of mining and processing equipment through the use of failure analysis and condition monitoring activities. Program results include an increase in equipment capacity and an overall reduction in operating costs. The identification of equipment failure modes and the development of associated capital asset management practices can minimize failure consequences. Successful programs have included; alterations to management practices, equipment modifications, and/or the implementation of condition monitoring programs. By controlling or minimizing the effects of incipient equipment failures, corrective actions can be taken earlier in the failure cycle, resulting in an associated reduction to repair costs and equipment down time.

Jan 1, 1997

By Xie Junjie, Li Shina, Ma Ruixin, Min Changli, Yin Zichen, Li Kang, Shi Zhuonan

Cesium and rubidium were effectively separated by zinc ferrocyanide coprecipitation method, and the effect of precipitant addition amount on the separation of cesium and rubidium was studied. Under the conditions of Zn/Cs molar ratio of 0.45 and Zn/Fe molar ratio of 1, the precipitation rate of cesium is 84.01% and the separation factor of Cs/Rb is 164.65. The thermogravimetric curves of the sediment were measured, and the effects of roasting temperature, roasting time, and leaching liquid/ solid ratio on the extraction of cesium were studied. Almost all of the cesium was extracted under optimal conditions: roasting temperature of 600 °C, roasting time of 3 h, leaching temperature of 25 °C, leaching time of 0.5 h, and liquid/solid ratio of 5:1 mL/g. After the leaching process, the leach liquor with high concentration of cesium of 80.17 g/L was obtained. Finally, the leach liquor was further purified by solvent extraction, and the purity of the cesium chloride product reached 99.66%.

Mar 17, 2024

By K. Darcovich

The wettabilities of agglomerates made from coals of several different ranks were measured by the adhesion technique. Oil levels from 0 to 10% by weight were used. As was expected, it was found that higher-rank coals are more easily oil-wetted and that the surface properties of the agglomerates correlate with agglomeration recovery and ash removal data.

Jan 1, 1992

By Gary Peach, Peter Mason

Planning and estimating progress rates and costs for tunnelling is always best done based on experience and historic precedent. Much precedent is available but the use of data monitoring, data mining and other retrieval techniques on modern TBM machines can enable this to be further expanded and refined. Advance rates can be related much more closely to rock types as can associated rock bolt and mesh/ shotcrete requirements. This in turn can lead to a further refinement in best likely combinations of equipment, such as shotcrete jumbos, better selected for the anticipated conditions, rather than the potential advance rates of the machine. Efficient and timely construction of the tunnel will also be linked to times needed for finishing work, such as contact and void grouting and to how this can be initiated while the TBM is still in operation, in order to save overall construction time. Indeed, this in turn may affect the most preferable layout and construction details of the permanent tunnel. Considerable experience has been gained in the use of two large diameter TBM tunnel drives through the Himalayas at the Neelum-Jhelum hydropower project in Pakistan. All the above aspects will be discussed in the paper based on the considerable experience and data which came from that operation, including appropriate measures in highly stressed areas potentially subject to rock burst.

Jun 13, 2021

Mineral processing plant operators are faced with the necessity to choose between many different possibilities for plant improvement. Only a few such possibilities, however, can be tested on the industrial site. Steady-state simulators make it possible to assess the effects of several different flowsheet modifications in a few days, thus helping the process engineer to make his choice implement the solution that seems the most appropriate and check it. The example described here is the crushing and grinding circuit of the Shila Gold Mine, jointly owned by CEDIMIN SA and BUENAVENTURA SA, in Peru. Several possible modifications for the purpose of increasing capacity have been simulated and the results assessed in terms of technical quality, investment costs and energy consumption. The best solution indicated by the USIM PAC simulator was implemented and gave a 20% increase in capacity with a pay-back time of two months.

Jan 1, 1993

By D. L. Monroe

Technical service is assuming an increasingly important role in the sale of asbestos fibre,, Manufacturers are examining raw materials more closely than ever before in order to, obtain the most efficient usage in their processes. Asbestos is one of the more difficult materials to evaluate and consequently has been are of the last to be subjected to evaluation. The main problem encountered in the evaluation of asbestos fibre is that minor differences in grade and texture are not shown up by chemical analysis, and are identified only by specialized physical analyses or actual production use. However, such minor differences become more critical as manufacturing processes are made more efficient, and many purchasing agents and plant chemists are applying a closer scrutiny to their supply of raw asbestos fibre. Many processes have been formulated around grades and qualities of asbestos fibre, which were standard some time ago, but which may now be subject to modification and improvement.

Jan 1, 1959

The implementation of NAFTA in January of 1994 was expected to have small but beneficial effects for the Mexican economy, mostly through increased investment flows. Mexico's mining industry was especially likely to benefit, as mineral investment funds would be diverted to the now safer Mexico and away from similarly endowed but more risky Latin American mineral economies. The results of the past two years have shown that it is governments and macroeconomic factors that influence investment flows, rather than the fine-tuning of trade flows through so called "free-trade" agreements.

Jan 1, 1996

By J. B. Davis

Isotope analyses distinguish biogenic sulfur ores from non-biogenic ores, but do not distinguish bioepigenetic from biosyngenetic ores. Sulfur deposits of salt dome caprocks and of bedded Permian evaporites of west Texas, however, are clearly bioepigenetic. Anhydrite, introduced by salt diapirs into geologically younger sediments, is converted biogenically to sulfur and calcite in the presence of petroleum; for example, in Challenger Knoll, a salt dome at a water depth of 3600 m in the Gulf of Mexico. Bedded evaporites of west Texas in association with petroleum show an obvious epigenetic replacement of the anhydrite layers by biogenic sulfur and calcite

Jan 1, 1978

By H. L. Lovell

The growing production of fly ash with the many attendant problems of economics, disposal and potential uses suggests an urgent need to consider those properties which are basic in its beneficiation. Fly ash is extremely variable and heterogeneous in all respects except its fine size. Because of its production in huge quantities, it becomes significant as a potential raw material. Detailed data are presented describing particle size and shape, density distribution and magnetic characteristics. The major components include combustible residuals, magnetite and silicates. These data are discussed in terms of beneficiation processes and uses, The results of air classification to produce a uniformly fine-sized low combustible product are encouraging. It is proposed that major increases in the future use of fly ash, must involve some form of beneficiation. Both the coal producing industries and the consuming utilities would benefit from increased utilization.

Jan 1, 1964