Search Documents

By J. W. Leonard

Gravity based coal/mineral preparation plants must be operated to yield products of a quality satisfactory to existing markets; but, because of historic control problems, recovery is frequently sacrificed to achieve quality resulting in losses of valuable product. Plant control has ranged from intuitive in-plant spot quality judgments made by various operators to gross methods involving such devices as density gauges, floats, grab-sample on-the-spot sink-float tests, etc. Millions of tons of quality coal/minerals are lost to refuse each year, because of the historic lack of a continuous and dependable control system. The result is both serious economic as well as environmental losses. While the economic losses are obvious, less obvious environmental losses, in the case of coal, result from the misplacement of more ignitable quality fuel to refuse banks. A control system capable of supplying a market-grade coal/mineral product, while continuously minimizing product losses to refuse, has until recently escaped technology.

Jan 1, 1991

By Alfred A. Roetzer

In several sections of the country new demands are being brought bar cement users. Among these the demand' for truck shipments; and palletized loads present new problems that do not lend themselves to sample solution. In fact these demands have far-reaching effect in the way bagged cement might be marketed. Early solutions of palletized truck loads filled from existing packing and loading facilities have resulted in' slowdown in packing, additional labor and space for palletizing, considerable experimentation in type and construction of pallets, and usually far from optimum truck handling and loading methods.

Jan 1, 1961

By F. Seymour

A dynamic programming algorithm is presented that takes a series of nested phases, a fixed mining rate schedule, a fixed plant production capacity schedule, and finds the mining and cutoff grade sequence that maximizes the Net Present Value. This tool allows the Mining Engineer to quickly look at project sensitivity to various production capacities, commodity prices, and costs. A description of the algorithm is given along with examples of how it has been used at Newmont.

Jan 1, 1995

By R. C. Babcock

Exploration for mineral deposits in the western United States is increasing annually, and the data generated by this effort are increasingly complex, diverse, and abundant. It is obvious that to make full use of this data base, which is both private and public, the technology of the computer must be involved. To lay out the framework for discussion of the particular uses of computers in all steps of exploration, this chapter will discuss the various approaches to the reconnaissance program which might be considered, the types of data to be acquired, the interpretation of these data, and the generation of recommendations based on this interpretation. Where possible, some of those areas where computer technology is now used will be pointed out. The discussion will cover the extent to which the computer is now utilized in those areas or where it should be brought into the program to aid in these activities. However, this chapter will not present an exhaustive evaluation of this technology, but will stress the exploration job and its requirements, so that subsequent discussion of the technology itself can be placed in perspective.

Jan 1, 1979

By Archie W. Fletcher, R. J. Wesely, Nathaniel Arbiter, A. D. Zunkel

In contrast to pyrometallurgy's six thousand year history in the production of metals, that of hydrometallurgy is of relatively recent origin. The earliest reference to it at all was in the 16th century, with the first applications to copper in the 17th and 18th. In the 19th century, increased demands for pure metal resulted in development of electrolytic refining, and early in this century electrowinning. The rapid growth in wpper production in the present century, paricularly in the United States and Chile, stimulated the development of new technology for leaching, and for the recovery of copper from leach solutions. Solvent extraction has become a major factor during the past quarter century by permitting novel leaching technology which produces dilute or complex solutions. In addition, solvents other than sulphuric acid, and chemical methods for precipitating copper metal are now of increasing interest. These are trends which should grow in importance in the future with the need to process lower grade and more complex materials. The evolution of copper hydrometallurgy is reviewed briefly and key factors in recent major developments are presented with details of specific operations and with trends for the future indicated. The relative importance of copper hydrometallurgy is compared to that of pyrometallurgy in the light of probable changes in ore supplies and character.

Jan 1, 1993

By Edward J. Adams

In recent years, there has been a shortage of individuals trained in the technical skills entering the mining industry. The university and industry, both indicating their concern, have joined efforts in an attempt to do something about this situation. An example of such an effort is the Pennsylvania State University's Student-Trainee Program in Mining Engineering, now in Its third year. The program is a five-year plan in which six months of schooling and six months of on-the-job training are alternated, climaxed by the student trainee earning a Bachelor of Science Degree in Mining Engineering plus two years of practical experience. The student trainee accepts the work-study plan as a satisfactory method of receiving a thorough education and preparing fog a career in the mining industry. Inasmuch as the work and study-periods are alternated, the trainee has an opportunity' to integrate his practical experience with his academic knowledge. He receives a chance to observe others perform she duties of the profession he is preparing to pursue, and he regards this as an essential part of any such cooperative effort. Even though there are some disadvantages, the trainee feels that the advantages of the program are definitely more decisive.

Jan 1, 1963

By Yi Luo

Bolting the mine roof is one of the noisiest underground mining operations. The main contribution to the high noise is the drilling of the roof bolt holes, especially in hard rock. A previous research shows that the specific energy consumed in drilling the bolt holes is inversely proportional to the bite depth (i.e., penetration per drill revolution). Less specific energy at a reasonably high bite depth means less energy is wasted in the drilling process to produce heat, bit wear and noise. Therefore, control of drilling operation to achieve a higher bite depth can provide an opportunity to reduce drilling noise from its sources as a proactive noise control approach. In order to explore the feasibility and to develop the proactive technology for reducing drilling noise, drilling tests have been conducted in laboratory settings. The preliminary results show significant reduction in noise dose can be achieved by drilling in medium hard rock at a reasonably high bite depth. This paper presents the findings from the laboratory experimental studies conducted so far.

Jan 1, 2013

By J. Liniecki, w. Chruscielewski, T. Domanski

INTRODUCTION Mining is the Polish greatest industry employing about 350 thousand miners in more than a hundred underground mines. The mining regions are located mainly in the south of the country - see Fig. 1. [ ] The coal mining dominates, however, and the zinc-lead and copper-ore mines presently employ about 16000 miners. All these mines are rather deep and wet. Their drawing shafts are between a hundred to more then thousand meters deep. The cross-adit of working area of mines ranges from several kilometers to a few tens of kilometers. The numbers of mines per mine differ also considerably and depend on the territory and type of mines. The largest coal mines employ about ten thousand miners but the largest metal ore mines do not employ more than four thousand miners. In all the mines the electric motors or diesel engines are being used. The intensity of mine ventilation, characterized by the volume of fresh air injected in to the main ventilating shaft per miner and per unit of the power consumed by the engines is about 6 cubic meters per minute per man and per horsepower. The studies of the potential alpha energy of radon daughter products /RnDP/ could be divided into the three developmental stages: I-st - stage /1966-1970/ the stage of so called Pilot Survey. During this stage concentration of potential alpha energy of RnDP in the air was measured in selected typical mines in all mining regions of the country. II-nd - stage /1972-1974/ was the periodical control of concentration of potential alpha energy of RnDP in the air of zinc-lead and copper-ore mines which have been chosen and recognized during the first stage as being the most hazardous ones. Air-sampling system /ASS/ measurements were applied during this stage.

Jan 1, 1981

By F. Dingwu

The demand of manufacturing high-purity magnetite concentrate leads to the advent of various magnetic separators. A novel magnetic drum separator has been developed with an optimal permanent magnet system and a complex-forces field is adopted, involving magnetic force, gravitation, fluid resistance, friction, inertial centrifugal force, etc. Proper ultrasonic probes are inserted into the bottom tank to break up the magnetic floes. The performance of magnetite in the complex-forces field is described and the optimal operation conditions are suggested.

Jan 1, 1995

By John G. Myers, William A. Vogely, Harold J. Barnett

INTRODUCTION, CONCEPTS, AND MEASUREMENT Introduction Periods in the history of man, from his earliest appearance to the present, are often characterized by the principal materials used. In nearly all cases, the material or fuel is of mineral origin-stone, copper, bronze, iron, coal, and so forth-indicating the principal ingredient of the tools or source of power of the period. Each of these periods represented great improvement over the preceding one in terms of human well-being, as measured by population growth and other indicators (Cipolla, 1978). A major reason for the improvements in production and well-being was the nature of the material or fuel, each successively superior to the preceding, which made it possible to produce more food, fuel, shelter, and clothing with a given amount of labor. If we accept this well-documented description of economic progress as accurate, we may then turn to the consideration of two related questions concerning this development. The first, easily answered,-is why man spent long periods of time (millenia, in many cases) making tools from inferior materials, such as copper, instead of passing directly to superior materials, such as iron and steel. The second, closely related question, concerns the relation between the rate of economic growth and the quantity of mineral reserves available at any time. For the first question, the answer is that the technology required to discover, extract, and process each successive material had to be discovered and developed before the material could be used. Once the technology was available, the new material could be and was exploited widely, raising productivity-output per unit of labor- and consequent consumption per person. This familiar idea underlies a fundamental principle of the economics of resources, namely, at any time, available resources depend upon available technology. No mineral or other raw material is a resource unless the technology has been developed to utilize it. But once the technology is at hand, the new resources associated with it provide the means for economic growth and rising levels of living. This principle is subject to certain conditions. For example, governments or other institutions may prevent a mineral from being used, even though the technology is available. And, if a mineral is located in a remote place, transportation charges may make it uneconomic to exploit. Such minor qualifications do not, however, change the thrust of the argument that technology is the overriding determinant. With respect to the second question, it might seem apparent that the greater the quantity of reserves available, up to some point, the more economic growth will be facilitated. This line of reasoning leads to the conclusion that as re- serves are consumed the quantity available will be reduced and economic growth will eventually be restrained. Reasoning of this sort underlies much popular (and scholarly) thought, in which depletion of mineral and other resources is assumed to lead to constraints on economic growth, through higher materials costs and absolute limitations on materials use. Two important qualifications must be made to this explanation, however, which together

Jan 1, 1985

By Drew F. Holbrook

Most of the siliceous rocks of the Arkansas Novaculite are novaculite, but they also include some chert, siliceous shale and, rarely, sandstone. Novaculite is defined as a homogeneous mostly white or light-colored rock, translucent on thin edges, with a dull to waxy Juster, and comprised almost entirely of microcrystalline quartz. The most plausible theory of origin for novaculite is that primary silica from submarine volcanism was picked up by organisms and deposited as amorphous silica, which was subsequently converted to microcrystalline quartz (novaculite) through diagenesis. The Arkansas Novaculite crops out over an east-west distance of 200 miles in the Ouachita Mountains of Arkansas and Oklahoma. Three divisions of the formation have been defined: a Lower Division, almost entirely massive light-colored novaculite; a Middle Division of interbedded dark chert and shale; and an Upper Division of massive calcareous novaculite. The Lower Division and most of the Middle Division are Devonian in age, and the remainder of the Middle Division and all of the Upper Division are Mississippian. The massive novaculites of the Upper and Lower Division attain their maximum development along the southern and central outcrop belts of the formation in Arkansas, and it is these rocks that are the source of current silica production. The calcareous novaculite of the Upper Division weathers readily to a light-colored, porous, less brittle rock, and in places to tripoli deposits. Currently tripoli is mined from a single deposit near. Hot Springs, Arkansas, and the rock is processed for highly specialized filler and abrasive applications. In the vicinity of Hot Springs, Arkansas, certain novaculite layers from the Lower Division with unique textural characteristics are quarried and processed into whetstones. Several small quarries produce this rock for two local and one out-of-state whetstone-fabricating plants. Chemical analyses of composite samples of novaculite from both the Upper and Lower Divisions taken at widely separated localities average 99 percent SiOz indicating a substantial resource of high-silica rock.

Jan 1, 1978

By D. S. Ramey

In-situ leaching of the oxidized copper mineral resource at the San Manuel mine has proven to be a technically and economically viable method of copper extraction. Although this leaching method has been modeled to predict future production capabilities, the expected magnitude of the ultimate recovery from any portion of the present mine is not fully understood. A closely controlled test has been designed, constructed, and is now operating to determine the rate and magnitude of copper recovery. The test, initiated in June 1992, is scheduled to operate for approximately 18 months. This paper presents an overview of the test design and current results.

Jan 1, 1993

By Willaim A. Berg

Vegetative stabilization can help meet the esthetic objections and pollution problems posed by mine wastes. However, mine wastes are often unfavorable growth media and special treatments and techniques are needed for plant establishment and continued growth. The establishment of vegetation on mine wastes was the subject of many papers presented at the International Symposium on Ecology and Revegetation of Drastically Disturbed Areas held at Pennsylvania State University on August 3-16, 1969. This paper is a summary of those papers presented at the symposium that dealt with the nutritional and physical aspects of plant establishment on a variety of mine wastes. The synopsis presented is a combination of excerpts from the abstracts, notes on the oral presentations, and rough drafts of some of the papers. The papers will eventually be published in the symposium proceedings.

Jan 1, 1970

By Richard A. Williams

The design, modelling and simulation of solid-liquid mixers remains one of the least advanced aspects of minerals processing, due to difficulties in quantifying complex slurry hydrodynamics from first principles, and in acquiring reliable experimental data for model verification and development. This contribution describes the application of electrical resistance tomography (ERT) for three dimensional imaging of the concentration of mineral particulates in a slurry mixer as a function of key process variables (particle size, impeller type, agitation speed). It is demonstrated how ERT can provide a wealth of detailed data to allow model development, which ultimately will lead to much improved design capabilities and the generation of mixing models which could reside within Particle Process Simulators. This principle is illustrated using descriptions of mixer behaviour based on an empirical approach, although the measurement methodology described is equally suited to development of computational fluid dynamics models, cellular models or design approaches based on artificial intelligence. The experimental data can be built into a visualisation data bank, which acts as a "process toolkit" by allowing a library of process responses to be catalogued. Hence these data can be accessed for the purposes of model development, equipment selection, optimisation of operating conditions or testing on-line control strategies.

Jan 1, 1995

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 G. S. Adisoma, J. J. K. Daemen, R. O. Roko

A common assumption in determining the shear strength of a rock joint using a direct shear test is that the surfaces undergoing relative shear are in complete contact. Furthermore, the limiting displacement associated with the residual strength values is obtained based on engineering judgement through visual inspection of shear force versus displacement curves. This study proposes a systematic way of determining the residual shear strength of rock joints by evaluating the limiting displacement leading to a minimum cohesive strength value and taking the true area of contact into account. The results of the study indicate that there is a limiting displacement associated with the residual shear strength, and some rocks may have an inherent interface residual cohesive strength different from zero. When the cohesion is different from zero, the residual shear strength is likely to be underestimated if the true area of contact is not considered. In the case where zero calculated cohesion is obtained, the area of contact has no bearing on the shear strength equation because the frictional force depends only on the normal load.

Jan 1, 1986

By Bonn J. Macy, David A. Gulley, William A. Vogely

INTRODUCTION Some of the most famous and graphic environmental incidents have arisen from mineral extraction, including oil spills, the Reserve Mining asbestos tailings case, Kaiparowitts surface mining and coal combustion, and other environmental causes celebre. The remote location of much of the mining industry to some extent reduces the human health hazards from pollution, but often times the pristine locale in which mining is conducted provides a sharp contrast to the impacting industry. This prompts questions as to what the research literature says about the true costs and benefits of environmental compliance. We survey the state of this knowledge. Where possible, we discuss studies focused on mining and related industries, such as primary metals production. In many cases, how- ever, the studies pertain to the economy as a whole. For present purposes, the mining industry is defined as companies engaged in the production and refinement of minerals, including metals, fuels, and nonmetallics (e.g., phosphate, sand and gravel). There are several stages in mining, with environmental effects occuring at every stage. The exploration stage comprises the period from initial prospecting to the point where the deposit has been located and delineated in sufficient detail to permit development decisions to be made. Geophysical and geochemical surveys, diamond drilling programs, and exploratory stripping and excavation are activities that may be employed during this stage. Some forms of prospecting are relatively benign, al- though even airborne surveys and motor vehicles generate noise pollution. Roads and the passage of vehicles and equipment affect land surfaces and vegetation, and attract heavier backcountry use. Clearings, stream crossings, and borrow pits can lead to increased erosion and sedimentation of streams. Geological survey grids disrupt vegetation and appearance. Moreover, prospecting can involve the excavation and stripping of overburden, resulting in soil and vegetation disruption as well as in- creased sedimentation of streams and lakes. The effects of exploration are often temporary, and frequently less severe than for other activities. Nevertheless, exploration-related impacts vary with the intensity and type of exploration effort, and can be significant. During the development stage of mining, shafts are sunk, pits excavated, buildings erected, and transportation facilities established. Dust, noise, and other socioeconomic and environmental impacts are generated by the relatively large and sudden influx of people, equipment, and activity. Surface disturbance and solid waste are generated by development, and liquid wastes form when mines are dewatered. The extraction phase is associated with a variety of environmental impacts. These impacts may differ for surface and underground mines. In surface mining, surface disturbance is obviously a major consequence. Piles of overburden and waste accumulation mar land surfaces. Wind and water erosion tend to spread the dis-

Jan 1, 1985

By Y. Zimmels, C. Feldman

Closed-circuit grinding processes are considered in the context of a reactor-separator circuit that involves multifraction streams and products. Because grinding circuits are low-efficiency, capital-intensive operations, modeling to maximize their economic return is appropriate. An attempt to develop and test such a model is presented in this work. The model relies on process simulation for both the mill and the separator, in conjunction with constraints imposed by product specifications. The grinding process was simulated using breakage functions, which provided complete data on the feed and product of the mill. A cyclone bank used as the separator was also simulated using known models. The overall process model provided a complete simulation of the multistream grinding and separation process. The process model was then incorporated into an economic model that predicts grinding cost, subject to process constraints, for a given set of operating variables. The model facilitates economic optimization of the grinding process as it relates to process variables and process hardware.

Jan 1, 1993

By W. E. L. Minter

The most important witwatersrand gold placers occur on extensive unconformity paleosurfaces that were produced during protracted periods of fluvial degradation. The erosional etches on what was generally unlithified substrate indicate that low sinuosity erosion patterns prevailed. The transport systems were dominantly braided fluvial with a minor debris-flow component. The placer sediments were non-cohesive sands and gravels which were evidently transported by fluctuating, yet perennial, discharges across extensive, low relief, bra1dplains, not far from littoral environments. Progress made in understanding heavy-mineral transport processes now emphasizes the importance that selective entrainment probably had in producing concentrations. Cognizance that these characteristics are not unique to the Witwatersrand should be taken into account when designing exploration models.

Jan 1, 1988

By L. Whitby-Costescu

The Shebandowan mine and concentrator, with a capacity of 9072 t/week (10,000 st per week), was opened in 1972 after several years of environmental study and planning. The mine is located in a popular vacation cottage .area about 96 km (60 miles) west of Thunder Bay, Ontario. Undertaken before environmental assessment procedures had become an established requirement, Shebandowan is one of the first Canadian examples of effectively integrating environmental work into overall planning. Although it is an underground mine, many of the environmental considerations are common to open-pit operations, and hence, it provides a case history for the use of all mine planners. Computers can play a part in such studies by simulating the annual production of mine wastes, by on-line polling of environmental sensors and by processing sensor data. Early attention was focused on establishing base-line conditions in a two-year water quality monitoring program. Since production began, water quality monitoring has shown that mining has not caused any significant changes. However, mine drainage disposal arrangements had to be modified in the light of operating experience. There is no townsite associated with the mine, and workers commute from established municipalities. Harmonious relations have been achieved with local cottage residents after their initial fears were dispelled. Plans are ready to begin revegetating the tailings when a sufficient area of dry elevated tailings has been accumulated. Rehabilitation of the land disturbed during development was begun before start-up and was completed during initial operations.

Jan 1, 1979