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By M. J. Shulman

The exploration geologist is frequently confronted with the problem of allocating his resources, i.e., exploration effort, among various areas. Although geologic, financial, and logistic considerations influence the allocations, no objective criterion is usually given that determines the optimal allocation. Maximizing the expected gain in information, subject to the constraint of a limited exploration budget, is used as the objective criterion to allocate airborne reconnaissance effort. The information function, I(x), quantifies the expected gain in information, where x is the scale of exploration. To calculate the information function, the following probabilities are required: the probability that an area contains a deposit; the probability that an anomaly is produced by the target; and the probability that an anomaly is produced by a barren area (false signal). Alternatively, the barren areas can be replaced by other targets. To illustrate the allocation method, the optimal number of line kilometers, i.e., the optimal line spacing per area, is determined for an aeromagnetic survey for iron in Egypt.

Jan 1, 1987

By D. Oyler

The National Institute for Occupational Safety and Health’s(NIOSH) Pittsburgh Research Laboratory (PRL), RAG Pennsylvania and Strata Control Technologies of Australia have collaborated to conduct an extensive study of roof bolt strata interaction at the Emerald mine in Southwestern Pennsylvania. The primary goal of the project was to obtain detailed data on the interaction between the mine roof and the support elements for use in modeling studies. The study site was a longwall tailgate subjected to high horizontal stress. Three arrays of instruments were installed at the site, one in the tail-gate entry and two in an adjacent crosscut. Pumpable concrete cribs were present in the tailgate array, and cable bolts were installed in one of the crosscut arrays. The instruments included mechanical and sonic extensometers for measuring roof movement, instrumented roof bolts, and three-dimensional roof stress cells. The study was ultimately successful in determining the magnitude of the horizontal stress concentration, the height of roof failure and the roof failure sequence, and the loading history of the primary roof supports.

Jan 1, 2004

By Mark S. Dunsbier, Steven J. Schatzel

Large roof outbursts began occurring in November 1986 at Domtar's Sifto Salt Mine in Goderich, Ontario, Canada, working the bedded Salina A-2 Salt unit. The outbursts, measuring about 13-20 m in diameter, released high concentrations of methane from cavities that extended into carbonate roof units. Spontaneous ignitions of methane gas during an outburst seriously burned a mine technician. The Canadian Ministry of Labour contacted the U.S. Bureau of Mines for technical assistance to aid in mine managements1 efforts in alleviating the problem. Initial gas content determinations of salt samples from the outbursts by acoustic test methodology revealed no methane enrichment. In- mine core drilling and subsequent methane content testing indicates the main source of methane in overlying roof units. Drilling the roof units demonstrated the potential of draining methane from areas showing signs of impending outbursting and alleviating the danger. Three mechanisms are considered the most likely means by which methane was introduced to the mine environment. These are (1) hydrocarbon gases released from brines, (2) gas transport along horizontal bedding planes or gas accumulations in bedding separations, and (3) mining-induced fracturing. The abundance of higher hydrocarbons in gas yielded by non-evaporite rock samples from the Goderich mine may be indicative of a former association with liquid petroleum.

Jan 1, 1989

By Fred A. Glover

It's a pleasure to be included with this group. I am not here to sell my services, but rather to share with you some ideas and considerations on using environmental consultants. Environmental consultants have developed some problems as well as created new costs for companies that are as legitimate as engineering costs. Each day the mining industry is becoming more affected by the proliferation of environmental regulations and their interpretations by federal and state agencies. How does a modern mining company cope with all the demands for environmental consideration by regulatory agencies and special interest environmental groups-- yet produce a product and make a profit? One way is to make efficient use of environmental consultants. But, as everyone here knows, this approach has been fraught with seemingly inherent frustrations, difficulties, and much justified criticism.

Jan 1, 1979

By S. K. Kawatra, T. C. Eisele

Pyrite depression is of great interest in sulfide mineral flotation, where pyrite is a common gangue mineral. Since the floatability of pyrite is a function of the pH and a variety of other chemical factors, pH control is a critical part of sulfide flotation circuits. A wide variety of pyrite-depressing chemicals have been studied and used in sulfide- mineral processing, with considerable success. However, there are certain applications where there are still no satisfactory pyrite depressants, and even when suitable depressants are available, there is always a need for less-expensive reagents. Microorganisms, such as the bacteria Thiobacillus ferrooxidans, are known to depress pyrite flotation. However, the dependence of the depression on the type of organism or on suspension pH is still being determined. In this study, the relative effectiveness of various microorganisms, and the effect of pH, has been examined. Screening tests using microflotation showed that every microorganism tested was capable of depressing naturally hydrophobic pyrite at acidic pH. Larger-scale experiments with two of the screened organisms and two different pyrites showed that microorganisms are very effective depressants at acid pH, but are largely ineffective at neutral and alkaline pH where the pyrite surface is not naturally hydrophobic.

Jan 1, 1994

By T. A. Griffin

Gentlemen: The subject of this paper is: ADVANCED APPLICATIONS OF BUCKET WHEEL EXCAVATORS AND RECLAIMERS. Against an urgent world wide energy crisis, the role of bucket wheel excavators and reclaimers in the surface mining of fossil fuels and other ores has been raised to new prominence. This paper will review the reasons for the expanded application of bucket wheel technology, its unique contributions, and other factors relative to volume, cost, versatility, and efficiency. Today, surface mining is faced with the twin challenge of (1), accelerating the rate of removal of massive quantities of overburden and ore, and (2), replacing comparable high volumes of overburden back into the mined-out portion of the pit. Optimum quantitites for - a single electrical power plant now range from 5 to 15 million tons of coal per year. The use of bucket wheels offers the best method for meeting this challenge at lowest possible cost. For example, an advanced application that also satisfies environmental concerns involves the simultaneous functioning of two bucket wheel excavators during surface mining operations. Working at spaced intervals and different levels in conjunction with a transfer conveyor and stacker, one excavator removes the ore while the other one transfers overburden to a stacker that replaces it back into the open pit. The result of this continuously operating cycle is: (1) removal of ore and replacement of overburden back into the pit in massive quantities, (2) at accelerated volume and extreme low cost that cannot be matched by conventional loading machines of any size, and (3) fulfills a basic environmental requirement which is to

Jan 1, 1974

By Verne Huser

The intensity of environmental conflict, the delays and legal battles that have marked the 1970's suggest the need for additional processes to resolve environmental disputes. Our present means frequently fail to address the real issues separating individuals and institutions. They are primarily adversary processes that foster polarization and reduce cooperative efforts. At the Office of Environmental Mediation, we have no quarrel with adversary processes nor with polarization, for both serve as important spurs to necessary change. We do seek cooperation among parties at a point where there can be a realistic expectation of success in facilitating a resolution of their mutual differences.

Jan 1, 1979

By D. Yadon, P. Lee, W. Kelly, C. Stilwell

Rico is a small town in an old zinc mining district in a mountain valley of southeastern Colorado. Mine waste rock and mill “tailings” remained after over 100 years of mining in the area, leaving associated surface water and groundwater impacts. Atlantic Richfield Company is proposing an innovative approach, which uses lime precipitation and wetland ponds (semi-natural system, also called treatment lagoon in a wetland setting) to treat adit water in the Rico area. Besides using a non-conventional treatment approach, a non-conventional (non-Superfund) regulatory/administrative approach is being proposed. This paper will focus on the water treatment issues and solutions, as well as describing the innovative “watershed” regulatory process.

Jan 1, 2004

By H. Knorre, A. Griffiths, J. Loroesch

Introduction Hydrogen peroxide is known to the mining industry as a powerful oxidant. able to attack and to destroy cyanide, the most important leaching reagent (Knorre and Griffiths, 1984; Griffiths, 1988; Griffiths, 1988). [ ] The most recent development, however, is the use of H2O2 as an oxidant in the cyanidation of precious metals. This application may appear to be a contradiction to the above mentioned detoxification process. This can, indeed, be the case if certain conditions are not considered carefully. Degussa has developed a new process to enable the application of H2O, in this field without having any detrimental effect on the cyanide. The incentive to seek an oxygen supplier like H2O2 instead of air was the fact that one of the most important conditions for the fast dissolution of gold is the presence of physically dissolved oxygen in the pulp (Kydryk and Kellog, 1954; Warstell, 1987). [ ] Complete gold recovery within a reasonable leaching time may only be achieved if the pulp is saturated with dissolved oxygen. Gold losses in leach operations mainly occur due to the following reasons: In some cases, the saturation of oxygen in the pulp cannot be achieved by aeration due to the difficulty to transfer oxygen from the gaseous into the liquid phase. This happens, for example, in pulps with a high viscosity. In such cases, even violent aeration only results in a low concentration of dissolved oxygen in the pulp. In any case, the starting phase of leaching requires the highest amount of oxygen. Therefore, it is especially important to raise the dissolved oxygen level to saturation in the starting phase. Peroxide assisted leach process (PAL) The intention of the process is to introduce oxygen in a liquid form. As a result of intensive research work, it could be shown that hydrogen peroxide can be used as a source of oxygen in the leaching of gold ores. To avoid side reactions, the following conditions must be applied: Hydrogen peroxide must be diluted before it is added to the pulp. The dosage of H2O, must be properly regulated based on the oxygen level of the pulp. An important part of the continuous O, control is a special oxygen electrode, which resists the extremely abrasive action of the pulp.

Jan 1, 1990

By Keith G. Wallace, Robert Wise, Ian J. Duckworth

This paper describes a case study for the ventilation planning at Utah Fuel Company's Skyline Mines which are located outside Price. Utah. The Skyline Mines are currently comprised of two longwall coal mining blocks located in two different mines. A third replacement longwall block is currently being developed. Future ventilation systems for the mines were determined by establishing ventilation models developed from data collected during a detailed ventilation survey. The paper discusses the challenge to coordinate immediate ventilation requirements with long-term demands. The continuous movement of the longwall, which frequently represented the only open split in the ventilation network, resulted in cyclic ventilation demands dependent upon the length of the tailgate. A series of system configuration changes were recommended based on the results of the network modeling exercise and an economic evaluation of the various options. The scope and cost of the configuration changes, and the mead improvement resulting from these changes is discussed.

Jan 1, 1995

By Mulong Yu, Yosry A. Attia

Beneficiation of high magnesium Florida phosphates requires ultrafine grinding to liberate the dolomite (the main source of magnesium), and a separation process capable of dealing with ultrafine sizes such as selective flocculation. The objective of this study was to investigate the feasibility of separating dolomite from apatite ultrafines by selective flocculation. To achieve this objective, selective polymeric reagents to either dolomite or apatite must be first designed and synthesized. This challenging task was accomplished by carefully selecting complexing/chelating agents which are selective to either the Ca or Mg ionic sites on the minerals, and incorporating these reagents into the structure of long chain water soluble polymers to obtain either selective flocculants (with high molecular weight, MW, polymers), or selective dispersants (with low MW polymers) to either the dolomite or the apatite particles. Synthesis and testing of these polymers on individual and mixed mineral slurries, and on a sample of natural high magnesium phosphate ore, have been attempted and the results are described in the paper. The preliminary results showed encouraging signs for the feasibility of selective flocculation separation of dolomite from apatite.

Jan 1, 1993

By R. Q. Honaker

Recent studies conducted at Virginia Tech have shown that ultrafine coal particles can be selectively coagulated and separated from mineral matter without the use of traditional agglomerants or flocculating agents. This technique utilizes hydrophobic interaction forces to induce coagulation of coal particles, while particles of mineral matter are dispersed using pH control. After selective coagulation, the coal coagula can be recovered by a sedimentation technique. In the present work, factors such as pH, particle size, and solids concentration have been examined. A wide range of coal samples have been successfully upgraded using this technique.

Jan 1, 1991

By Terry L. Muldoon

On July 7, 1971, noise regulations for underground coal mines were implemented under provisions set forth in the Federal Coal Mine Health and Safety Act of 1969. These same regulations now also apply to coal mine surface facilities. In August 1971, in anticipation of these regulations, the Bureau of Mines, through the cooperation of the mine operators, conducted extensive noise surveys in three coal cleaning plants. The survey was conducted in an attempt to identify those occupations where exposures would exceed the proposed regulations.

Jan 1, 1972

By Rogério C. Guimarães, Antonio E. C. Peres

Arafertil's oxidized ore presents barite grades that oscillate between 5 and 12%. The barite separation plays a major role in the production of apatite concentrates for the manufacturing of phosphate fertilizers. The selectivity, via flotation, in the system barite-apatite is inherently difficult due to the similarity of the physical/chemical characteristics of these minerals. The evaluation of the relevant aspects of this separation was performed based on the determinations of the electrical surface charge of barite and apatite, the abstraction isotherms of cetyl-stearyl sodium sulfate and fatty acids soaps for barite and apatite, microflotation in a modified Hallimond tube, and flotation tests in a batch column. The results showed that the adsorption of cetyl- stearyl sodium sulfate occurs preferentially onto barite, in comparison with apatite. On the other hand, the rice bran oil soap presents similar adsorption levels onto both barite and apatite. The cetyl-stearyl sodium sulfate was selective as a barite collector in the presence of apatite, a fact that was not observed in the case of rice bran oil soap.

Jan 1, 1999

By David Morrison

On the Corramandel Peninsula of New Zealand, the Waihi Gold Mine has undergone a major redevelopment. The upgrade included the construction of two very large overland belt conveyors, both rated for a capacity of 6000tph. The first of these conveyors (CVR2) traverses a total of 1600m over undulating terrain, including a significant section running through tunnels. A large hill is climbed, just after the mid-section of the conveyor run, before dropping back down prior the discharge point. The second of these conveyors (CVR8) traverses 1100m along an alignment with a horizontal curve, a number of vertical curves and a significant lift before the discharge point. The CVR8 conveyor also included a shuttling head pulley arrangement. The mine they service is inside the town of Waihi. The conveyor alignment runs through the town and out to the metallurgical process site on the outskirts of the municipal area. This paper documents the engineering process that took place in the design of these conveyors. The Martha Hill mine in Waihi, New Zealand is unique. The mine is placed in the township. Consequently there are quite stringent environmental limitations on the mine's operation. In [Figure 1] the proximity of the mine to the town is shown. In the top-centre of the photograph the alignment of the existing smaller overland conveyor can be seen leading from the mine to a tunnel through the hill in the background.

Jan 1, 2000

By G. Gillet

The conventional magnetic separators used in the mineral industry are equipped with traditional magnetic circuits or with permanent magnets (rare earth). However, when processing minerals with low magnetic susceptibilities or minerals of very small particle size, these separators are inefficient. In addition, a conventional magnetic circuit consumes considerable amounts of electricity to generate a relatively low magnetic field (~2 Tesla). The equipment is also heavy and bulky. Only a separator having a superconducting sole-noid can contribute in solving most of the problems, and only such a separator can produce high magnetic fields with low energy consumption. New developments and the experience acquired in using these superconducting magnets have resulted in new uses for magnetic separation, especially in the environmental area. This paper presents and describes a separation system that uses superconducting magnets that are completely automated and able to treat raw materials (concentration or purification) or liquid industrial effluents containing heavy metals in solution. Several industrial sectors, including the surface treatment, petroleum and chemical industries, are generating effluents containing heavy metal ions. The main metal ions found in such effluents include zinc, copper and vanadium. The purification of such effluents by magnetic separation is performed by adding a certain proportion of iron salts. The treated effluent passes through a superconducting separator where the flocs are retained in a matrix of steel wires. The efficiency of supraconducting high-gradient magnetic separation (HGMS) by this method exceeds 95%. Mineral separation and industrial-waste purification results are presented.

Jan 1, 2000

By I. Koliabina

In this paper, the results of mathematical modeling of casing pipes decontamination from radio-active new mineral forms directly in boreholes using hydrochloric and hydro-silicic-fluoric acids are presented. Modeling for highly and low radioactive coatings on the walls of casing pipes of Anastasievka oil-and-gas deposit was performed using GEMS software, based on the method of Gibbs energy minimization. Calculations have shown that thorianite and goethite, that are present in low-active crusts, detected in casing pipes uplifted from comparatively low depths, are well dissolved in hydrochloric acid, but radiobarite is almost insoluble. For the same acid concentrations, almost all radiobarite of high-active coatings detected in pipes uplifted from considerable depth is dissolved. To evaluate the possibility of decontamination of pipes from radiobarite of low-active coatings, modeling of crust dissolution under the action of H2SiF6 has been performed. The results have shown that for acid concentrations of more than 13 % almost all Ra and Ba are dissolved while all iron and thorium remains in goethite-thorianite solid solution. For the same acid concentration, almost all radiobarite from high-active coatings is dissolved. Therefore, no reagent allows decontamination of pipes from coatings of both types. It seems that successive or simultaneous use of both reagents (HCl and H2SiF6) in certain ratio is required. To clarify this issue, further experimental and model investigations are necessary. The issue of decontamination of casing pipes from galena that is present in high-active crusts also needs to be clarified.

Jan 1, 2005

Some basic terms used in cost management and accounting include: - Cost. A sacrifice made to acquire goods or services, measured by the price paid. Technically, the sacrifice is called a cost until the benefits from the goods or services have expired, at which time the sacrifice is called an expense. In this text, the terms "cost" and "expense" are used interchangeably. - Revenue. An increase in the value of the firm resulting from the sales of goods and services. - Income. The excess of revenues over costs for a specified period. The term is often used with modifiers to indicate specific quantities on an income statement (e.g., pretax income; net income). - Activity. A measure of production work. Traditionally, physical production volume (tons of ore or units of product) has been used as the measure of activity. Other measures include direct labor hours, equipment operating hours, and quantity of materials or supplies consumed. - Responsibility center. A segment of an organization that is responsible for a specified set of activities. In mining, individual operating divisions can be treated as responsibility centers, known as profit or cost centers. Departments within a division are generally treated as cost centers. - Cost center. A portion of an organization having responsibility for achieving specified levels of cost. - Profit center. A portion of an organization having responsibility for achieving specified levels of profit (revenues and costs).

Jan 1, 1999

By J. S. Murty

In this paper, a report is given of studies undertaken in a laboratory rod mill to obtain the optimum conditions for the desired particle size distribution for long-distance transportation of coal through slurry pipelines.

Jan 1, 1987

By S. G. Malghan, V. K. Pujari

Detailed characterization of all the powder constituents during powder processing is necessary for the reproducible manufacture of ceramic components that will perform reliably in intended applications. In this paper, selected physical and surface chemical techniques for characterization of silicon nitride powder are evaluated. The characterization data are discussed in the context of how these data, through their influence on powder processing unit operations, can affect the final microstructure. In the forming of ceramics, some of the major variables of injection molding are evaluated. Accurate measurement and control of these variables is emphasized for manufacture of Si3N4 ceramics with a high degree of reliability.

Jan 1, 1990