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By G. M. L. Robinson

Mineral Processing Wastes, as defined by the Environmental Protection Agency (EPA), has determined that most of the mine wastes will be regulated pursuant to subtitle D (Solid Waste Regulations) of the Solid Waste Disposal Act while specific mine waste categories will be regulated within the framework of the Toxic Substance Control Act. Though EPA's determination currently relieves the industry of the regulatory constraints mandated by the Resource Conservation and Recovery Act (Hazardous Waste Regulations) Subtitle C regulatory framework; the industry is not granted immunity from historical or current environmental regulations related to listed or characteristically hazardous or solid wastes. Because of the current regulatory trends and the need to implement cost effective remediation alternatives; advanced currently available on-site remediation technologies are available to minimize, reduce, contain or prevent environmental impacts related to mining and processing activities. In light of industry technical needs, an overview of the research and commercially available remediation technologies will be discussed and a brief discussion of the strengths and weakness of each technology will be presented. Technologies to be discussed includes stabilization, solidification, soil wash, soil flush, thermal distillation, pump and treat, metal extraction, centrifuges, filter presses, bioremediation, and incineration.

Jan 1, 1992

By Milton H. Ward

The percentage of exploration dollars flowing out of the industrialized countries continues at an all-time high, and this shift in risk money is justified (Samuels, 1990; Bosson, 1977). Clearly, the odds of discovery are greatly enhanced if exploration is pursued in an untrampled and geologically more prospective environment. Unfortunately, such major unexplored areas of the developed world are shrinking rapidly, not just because the lands have already been tested, but primarily because they have been withdrawn from exploration. Experience, however, has shown that foreign investment is not without risks. These include problems that result from working in isolated areas, a lack of infrastructure, untrained workers and an absence of a solid geological data base. While the likelihood of once-feared expropriation is now low, mining enterprises still must take precautions to gain the support of their constituencies, including a variety of governments (local, provincial and central), workers, environmentalists, cultural organizations and local landowners. Is foreign exploration worth the risk? In most cases, Yes! But maintaining tenure and long-term success in a less developed country is only likely with good planning and the use of appropriate safeguards. These include measures such as buying country-risk insurance, building multinational relationships, forming joint investments, developing a broad customer base and seeking local investors in the company (Cobbe, 1979). The primary theme of this lecture is: How a company handles its constituency is critical to long-term tenure in a foreign country. Ideally, a multinational mining company would be so effective in dealing with the local people and managing its relationship with the host government that it would become a preferred employer, preferred over its competitors and over local companies. Historical overview Our earliest ancestors lived in Africa three to four million years ago. The Paleolithic or Old Stone Age, about 500,000 years ago, marked the beginning of mining in its earliest form (Gregory, 1980; Wolf, 1984). Various types of rocks and stones were used for tools and weapons, with flint being the preferred resource for implements. Initially, these materials were collected as stones (eoliths) lying on the surface. Then they came from excavations of flint in limestone beds that were exposed in river banks or naturally occurring excavations. Later, more formal mining developed. No doubt tribes of the Old Stone Age experienced conflict over rights to eoliths, food and land. The question of who owns the land and has rights to its contents and what is fair value for extraction is still the subject of intense debate and, occasionally, open conflict. As time passed, the search for useful minerals required migration from one area to another. Later, voyages from Europe to the New World and travels to other remote regions were funded and supported by absentee investors, kings and such (Rogers, 1976). The primary objective of such funding was to obtain gold, silver, food stuffs and other commodities that could be collected from the new countries. This is still the objective of foreign investment.

Jan 1, 1994

By George E. Niewiadomski

The exposure of miners to radon gas and its airborne daughter products is a serious health problem which has long been recognized in the uranium mining industry. The association of high exposure to alpha particle emitters with incidence of lung cancer is well established. There continues to be a pressing need to reduce and eventually eliminate the high incidence of occupational lung cancer among uranium miners through the development of new and improved measurement and control technologies. This paper highlights the current efforts of the Bureau of Mines radiation hazards research program. It is aimed at obtaining a fundamental understanding of the behavior and transport of radon and radon daughters, developing more accurate and reliable instruments and measurement methods and developing cost-effective control techniques. Also discussed are the most recent accomplishments and the future research plans of the program.

Jan 1, 1981

By G. T. Adel, W. Z. Choi

A model describing size reduction and mineral liberation during grinding has been extended to include multiple classes of composite particles. The majority of the model parameters have been directly determined using computerized image processing equipment to analyze the products from batch grinding tests. A coarse-grained sphalerite ore from Tennessee, representing a nearly ideal binary mixture of sphulerite and dolomite, has been used to experimentally validate the model for the case of dry batch grinding. In all cases, excellent agreement has been observed between the model predictions and the experimental results.

Jan 1, 1988

By Jae-Chun Lee, Kang-In Rhee, D. B. Dreisinger, Hyo-Shin Yu, G. A. Kordosky

The development of a process for direct synthesis of very pure ZnO powders from zinc-bearing waste was investigated. The zinc waste which contains 55% zinc was leached with sulfuric acid. After iron removal by hydrolysis from this zinc solution, purification through solvent extraction by the use of D2EHPA as an extractant was carried out. Then, loaded zinc in the organic solution was stripped and precipitated simultaneously using oxalic acid as a precipitant. Synthesized ZnC2O4 precursors by precipitation stripping were calcined to obtain ZnO powders exceeding 99.9% purity. The effects of sulfuric acid concentration, leaching time, and pulp density on the extraction of zinc were studied and optimum conditions for the solvent extraction were obtained through purification of the zinc solution. The size, morphology, and size distribution of synthesized ZnC204 powders were studied in terms of oxalic acid concentration, temperature, surfactant added, precipitation time, etc.

Jan 1, 1993

By Deepak Malhotra

Comminution circuits in general account for fifty percent of capital and operating costs for a processing plant. Significant advances have been made in optimization of these circuits. One would expect a few circuits to be the favored designs for plants. Review of grinding circuits worldwide indicates that a variety of circuit designs are utilized for non-technical reasons. A brief review of circuits and reasons for their selection is given in this paper.

Jan 1, 1998

By D. B. Jenkins, D. R. Taylor

Treatment of bentonite clay with mineral acids yields a modified clay product of high surface area and acidity that exhibits enhanced adsorptive and catalytic properties. A highly specialized segment of the clay industry based on this process has evolved into a worldwide business with a capacity of about 500 kt/a. This paper will present data on the chemistry, mining, manufacturing, and applications for acid-activated clays.

Jan 1, 1988

By J. A. Herbst, Y. C. Lo

An attempt has been made to parameterize the population balance model for a ball mill based on measurements of the elementary breakage process obtained using an ultrafast load cell device. Detailed insight obtained concerning the fragmentation of particle assemblies with the ultrafast load cell leads to a better understanding of ball mill grinding. The ball mill breakage function and specific selection function are derived from an average single event representing the multiple breakage events which occur in ball mill grinding. Since both the breakage function and the specific selection function depend on the loading mode in the mill, predictions of breakage mechanisms in ball mills are possible by using data obtained in various elementary loading modes. The application of this model to the description of batch ball milling behavior has resulted in reasonably accurate predictions of product size distributions for various energy inputs.

Jan 1, 1992

By E. J. Rorem

Rockfall and unstable rock slopes can be effectively controlled by utilizing steel wire rope net systems, either as barriers or as slope draping. The chief advantage of such systems over rigid type barriers is the flexibility of wire rope netting, permitting kinetic energy dissipation, yet providing high strength and consequently low maintenance. A review of the design considerations involved with these systems, as well as a review of several mine and non-mine installations is presented with the hope that the information may contribute to the safety against the dangers of rockfall and other mine hazards in active and abandoned mines.

Jan 1, 1996

By Dorothy A. Canter

Three Federal programs exist for identifying significant environmental chemicals, including minerals, that should be tested for toxicological effects. Two programs are mandated by law and can lead to industry-funded studies; they are administered by the Environmental Protection Agency and the Agency for Toxic Substances and Disease Registry, respectively. The third is the National Toxicology Program, a Federally-funded testing initiative. This paper summarizes the three programs, describes their similarities and differences, and discusses their applicability to minerals.

Jan 1, 1991

By Melvin W. Kraschnewski

In 1966 Central Ohio Coal Company and Bucyrus-Erie signed a contract authorizing Bucyrus-Erie Company to design and build a 220 cubic yard dragline. This dragline would be used for stripping overburden from their coal reserves located near Cumberland, Ohio. The size of the machine was arrived at after a thorough application study of their annual coal output requirement, depth of overburden and type of terrain. The design and construction of this machine which has been designated by BECO as model number 4250-W is the title of this paper. Size wise based on machine weight the 4250-W represents an increase factor of three over our largest current dragline. Probably the easiest way of presenting a machine of this size is to build it from the bottom up.

Jan 1, 1969

By K. Fuenkajorn, J. J. K. Daeme

Ring tension tests have been conducted on 229 mm (9 in) diameter disks of Grande basaltic andesite and Pomona basalt with various center hole sizes in order to study the relationship between ring tensile strength and relative hole radius (hole radius/disk radius). The tensile strength, [ ] decreases as the relative hole radius, [ ] increases. A power equation, [ ] where C and R represent the coefficients of strength and shape, respectively, adequately represents the ring tensile strength as a function of relative hole radius over the range investigated. This equation can be used to distinguish the effect of the hole size from the strength results, to predict the tensile strength of a ring sample containing arbitrary hole sizes, and to approximate the critical relative hole radius of the material tested.

Jan 1, 1986

By Erich U. Petersen, Robert B. Coleman, William J. Tafuri, Donald M. Hausen, P. R. Taylor, Douglas N. Halbe, D. W. Rodolff

The definition of refractory gold ores and concentrates, including mineralogical characteristics, is reviewed. The chemistry of roasting and process conditions such as feed size, temperature, and time are discussed. A typical metallurgical program for developing a roasting process scheme is presented. The application of various types of furnaces for roasting is described. Requirements for scrubbing off-gases to meet environmental air emission regulations, and general information regarding engineering design parameters for roasting are presented. Roasting is sound technology for processing refractory ores and concentrates, but it is essential that the metallurgy of each ore or concentrate is well defined before commercialization. A fluid-bed roaster is the preferred type of furnace for roasting. Environmental regulations for air emissions must be carefully addressed.

Jan 1, 1990

By C. Bemelmans, L. Chia, T. O’Keefe

Lead alloys function effectively as oxygen-evolving anodes in copper SX-EW operations, and they are highly resistant to corrosion. However, the presence of an organic (from solvent extraction circuits) in the electrolyte seems to enhance solution line attack. Laboratory tests showed that lead is soluble in D2EHPA, Acorga and LIX 984 to a limited, yet measurable, degree. Lead alloys and various lead phases formed on the anode were tested to evaluate their effect on the corrosion process in organic media. Possible causes for anode corrosion and mechanisms responsible for their initiation are discussed.

Jan 1, 1998

By J. P. Savely, D. E. Nicholas, R. D. Call

Slope stability is a probabilistic phenomenon and as such should be analyzed with probabilistic methods. Fracture orientations alone, insufficiently model the rock mass. Other parameters describing the fracture set characteristics are required with distributions that can be sampled to fit mathematical stability models. Important considerations are length, spacing, dip, waviness angle, and overlap. These parameters are of major concern in design and are difficult to measure. Reasonable estimates of the characteristics can be used to provide distributions.

Jan 1, 1977

By P. R. Taylor

A review of the advantages and disadvantages of plasma technology for metal and mineral wastes is presented. Examples of the use of plasma systems are given and possible future uses are outlined. Among the potential uses are treatment of electric arc furnace (EAF) dusts, the vitrification of nuclear wastes and the removal of toxic metals. Over the past few decades, plasma technology has been studied for potential applications over a wide range of metals/materials processing areas. One promising area of plasma technology applications is the treatment of industrial hazardous waste. The potential generation of hazardous and toxic waste by various industries has become a matter of public and political awareness. Environmental regulations have put stringent toxicity emission limits on disposable waste streams. An intensive research effort is currently underway in the area of hazardous waste treatment.

Jan 1, 1994

By M. C. Williams, T. P. Meloy

For over thirty years the Population Balance Model, PBM, has been the mainstream modeling method for comminution unit operations and comminution circuits. For commercial comminution circuits the method is based on erroneous physics and dubious numerical mathematical methods leading to non unique solutions that have little extrapolative value and faulty control strategies. In short the PBM is wrong. Given is a detailed analysis showing a number of non trivial flaws in the linear PBM. Moreover, a simpler model is presented that leads to a solution of the comminution circuit predicting the size distribution output over a variety of conditions. Because the linear PBM is firmly entrenched, an award is offered, $10,000, to any researcher that can use the linear PBM and its present numerical methods to predict the typical straight line, self similar, output of wet mills over a variety of grinding times.

Jan 1, 1992

By R. V. Ramani, J. Qin

During the mining process, the in-situ material is broken into different size ranges, from very large pieces to very fine particles. Some of the fine particles become airborne. In underground coal mining, airborne respirable dust is associated with health and safety of the miners. The amount and size distributions of airborne dust are important parameters to effective dust control measures. The design of underground mine experiments, including sampling procedures and sample analyses methods to determine these parameters are presented in this paper. A total of fifteen continuous miner cuts were sampled. The amount of dust generated during the cutting process and the relationship between total and respirable airborne dust concentrations and amounts are examined. The amount of respirable dust airborne is on the average only 0.016% of the respirable dust generated. On the average, 61% of the total airborne dust measured is in the respirable size range. The amount of respirable airborne is on the average 36% of the respirable size fraction in the total airborne dust. For equal proportion of rock and coal material cut, rock contributes about twice as much fines (=0.22 mm) as coal. Additional fundamental research is necessary to further the understanding of the airborne propensity of respirable dusts in mine atmospheres.

Jan 1, 1989

By Stefan Zanon, Ty Faechner, Clayton V. Deutsch

Secondary data are important in geostatistical simulation of continuous variables. Geophysical data and geological trends are used for modeling porosity and permeability. Multiple mineral grades must often be modeled for mining applications. Sequential Gaussian simulation (SGS) is often used because of its relative simplicity and robustness. The two most common approaches to integrate secondary data in Gaussian simulation are with (1) locally varying mean, or (2) collocated cokriging. A significant problem with both of these techniques is variance inflation, that is, the variance of the resulting simulated values is too high because of an inappropriate decision of stationarity or an artifact of choosing a single secondary data in presence of many. We introduce a self-healing procedure for dynamic correction of this problem. The dynamic correction is different for the locally varying mean approach and for collocated cokriging since there are different reasons why each of these methods causes variance inflation. The reasons for variance inflation are discussed and the self-healing is applied to a number of data sets.

Jan 1, 2002

By W. K. Utt, C. C. Woodward, W. L. Howie, G. G. Miller

The process of roof drilling and bolting is one of the most dangerous jobs in underground mining. In the United States, roof drilling and bolting results in about 1,000 accidents with injuries each year. Researchers, from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health are studying the feasibility of using a drill-monitoring system to estimate the strength of successive layers of rock and assess the integrity of a mine roof. Such a system would allow roof drill operators to be warned when a weak layer is being drilled. Using measurements taken during drilling, a neural network can classify mine roof strata in terms of relative strength. The concept has been proven in principle. This research project was undertaken to increase the safety of underground miners, especially those involved in roof bolting. The system should be applicable to the mobile drills now used in underground mines, and the system would likely find wider application as well.

Jan 1, 2003