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By A. L. Boerner

Off-highway tire costs represent a significant portion of the total mining costs in openpit, truck-shovel operations. To extend the lives of tires, the site-specific factors influencing tire life should be investigated Valuable data can be obtained by combining historical operational data captured by a mine dispatch system with detailed tire and maintenance histories. Assuming that failure counts satisfy a Poisson distribution, F-tests can be applied to determine significant deviations from desired or target counts. The methodology developed in this paper can be used to identify the haul routes and loading and dumping zones that have significantly higher incidences of tire failure. Corrective action can then be targeted at these zones by modifying the shovel or truck operator practices; changing the haul route maintenance and clean up practices; or altering the bench, ramp or waste dump design parameters. An example is given of the correlation of tire separation and tire impact failures with haul routes for a fleet of nine Caterpillar 793C trucks in operation at the Chuquicamata Mine in northern Chile. A high incidence of impact failures was observed for the ex pit ore crusher and for tires installed in the left outer rear position on the trucks. The latter was postulated to be due to a preference for drivers to execute right-hand turns prior to dumping. Recommendations were made to revise crusher and dump cleanup practices and investigate the feasibility of super-elevating the surface of dumping zones to reduce ground pressure on the left rear tires.

Jan 1, 2002

By Donald D. Born

Mine No. 95 is located in Harrison County about 5 miles west of Shinnston, WV, with coal properties covering the northwest corner of Harrison County and the southwest corner of Marion County and with adequate Pittsburgh seam reserves to support the mine for many years. The mine was opened in 1967 and was planned, projected and operated as a room and pillar mine. It is located on a spur branch of the Baltimore and Ohio Railroad, has rail loading facilities and shipped by rail during its development stage. In 1972 it was converted to a mine mouth power station supplier and now transports coal by conveyor belt directly to the Harrison Power Station of Allegheny Power System. In 1971 the first longwall unit was installed in a selected area of the mine and immediately an orderly system of planning was developed to overcome the restrictions associated with longwall mining. The first was the development of the technique necessary for the plugging of abandoned oil and gas wells that existed in the area. With the assistance of the Morgan- town Energy Research Center of the Bureau of Mines, this restriction was overcome and thus opened a great potential for longwall mining in northern West Virginia. Other restrictions that had to be considered for longwall planning were dwellings and other improvements, snap top zones, water courses, and adequate bleeder systems, and the handling and treatment of mine drainage. In 1975 the second longwall unit was installed and soon therefore became a total longwall mine.

Jan 1, 1986

Researchers at National Institute for Occupational Safety and Health (NIOSH) are investigating how fiber-reinforced shotcrete mix designs can be extrapolated from proven designs employing wire mesh. This paper explains the results of round determinate panel tests and relates the flexural strength and toughness of fiber-reinforced shotcrete to known energy absorbing properties of wire mesh. The energy absorbed with central deflection is strongly influenced by the amount of fibres. The higher the energy absorption the more load cracked shotcrete can support. Two types of fiber-reinforced shotcrete were investigated, one with steel fiber and another with polyfiber. The residual load supported in Round Determinate Panel Tests can be matched with the strength of wire mesh, thus providing equivalent bag strength values for fiber reinforced shotcrete panels. There is also evidence of a panel crack width comparison to the load holding capabilities of the fiber in the shotcrete mixes. In practice, this provides designers with a method for comparing the ground support provided by fiber-reinforced shotcrete with that supplied by wire mesh.

Jan 1, 2010

By T. V. Subrahmanyam

Unlike coarse particles (40-50 µm), the fines (<10 µm) have low collision efficiencies with gas bubbles in flotation process. Among the alternative methods for recovering the fines are their aggregation with coarse particles (carrier flotation) and flocculation of the fines alone (shear-flocculation), prior to flotation. In any case, hydrophobic aggregation is the mechanism involved though the technique is known by different names in literature. This paper deals with theory and state-of-the-art of particle aggregation. To illustrate the dependence of aggregation on particle hydrophobicity, charge and, in turn, the sheer force, the results of quartz-DDACI and galena-xanthate systems are considered. In the flotation of complex ores selectivity is achieved by chemical control and aggregation of particles of the same species is analogous to that; however, more work is necessary on ores for a better understanding of the pulp chemical aspects from the view point of selectivity in aggregation. For a few ores, the results of earlier workers confirm improved recoveries of fines by aggregation prior to flotation.

Jan 1, 1997

By Ashma Singh, Nichole Maistry

Due to declining iron ore grades, low-grade ores with complex mineralogy — namely, banded iron formation (BIF) — are being explored to maximize iron ore resources and increase the life of mine. Flotation is the standard global process used for the beneficiation of BIF ores, as it is a complex ore reserve, and liberation is typically achieved below 1 mm. This study focuses on the flotation of a South African BIF, evaluating its response to different collectors, as well as effect of grind. As flotation is an expensive process and South Africa ranks high on the production cost curve, preconcentration by gravity or magnetic separation is performed prior to flotation. Thus, flotation was also performed on a gravity concentrate to determine if a grade suitable for steelmaking (approximately 63 percent) is achievable. The results indicate that the use of an alkyl ether amine-based collector partially neutralized with acetic acid is suitable for separation of hematite from illite and quartz at high pH values. Further optimization tests are being pursued to improve overall recovery and grade.

May 1, 2025

By Ralph P. Hackl

Biooxidation processes for treating arsenical and other types of refractory gold ores are touted by many as being simple, inexpensive and environmentally friendly. One of the advantages claimed by proponents of biooxidation is that arsenic is disposed of as insoluble ferric arsenate which is suitable for long term disposal in tailings ponds. However, there is considerable controversy as to the stability of ferric arsenate with respect to re-dissolution of arsenic. In particular, there is concern that the amorphous ferric arsenate produced at low temperature is not stable, especially at the alkaline pH's required for cyanidation. There is a general lack of published information on the stability of arsenical bioleach tailings. Past work on ferric arsenate stability has usually involved purely chemical systems and the use of synthetically prepared precipitates. Upon completing the Salmita bioleach pilot plant campaign (Hackl and Wright, 1989) the author had the opportunity to test the stability of the arsenical bioleach/cyanide tailings which were produced. This paper summarizes the results of that work.

Jan 1, 1990

By Mark William Johns

Carbon-in-pulp (CIP) is the preferred method of gold recovery om cyanided plp. However, other gold adsorbents (namely, ton-exchange resms) are being introduced to the industry as they are considered to have several advantages over carbon for the recoery of gold. A set of test methods have been developed by the industry to evaluate the quality of different carbons. owever, many ?f these tests are not applicable to evaluating ton-exchange resms. Hence, a need has arisen for a method to evaluate the different adsorbents. This paper introduces a philosophy to evaluate an adsorbent that results in an estimation of the capital cost and the operating cost associated with the adsorbent. Tests that have been devel­ oped to evaluate the ability of an adsorbent to adsorb gold (in­solutton . counter-current) and to evaluate the optimum adsorbent for a specific pulp (in-pulp batch) are introduced. A method of converting the test data into an economic dimension is present­ed. Case studies are presented to highlight the discussion.

Jan 1, 1996

By Peter G. Mason

Pressure oxidation is now a well estab­lished process for the treatment of refracto­ry gold ores and concentrates. The process utilizes pure oxygen to oxidize mineral sulphides in an aqueous slurry at elevated temperature and pressure. Gold released from the sulphides becomes amenable to subsequent cyanidation. A major component of the operating cost of this process the supply of oxygen. The quantity required is dependent on the sul­phide grade, the extent of oxidation and the percentage utilization of the oxygen. As the sulphide grade is fixed and complete oxida­tion is generally required to maximize gold liberation, the only opportunity for saving in oxygen consumption is to improve its utilization. Under circumstances where the feed material contains substantial carbonate, oxygen utilization can be improved by strip­ping carbon dioxide from the autoclave vent and recycling the associated oxygen. Fluor Daniel Wright included an oxygen recycle circuit in the Getchell pressure oxidation plant, which is operated by First­Miss Gold in Nevada. FirstMiss Gold has applied for patent rights to the process as implemented at Getchell.

Jan 1, 1990

By J. Tuck

This paper reports on an ongoing exploratory research program which aims to develop an understanding of the relationships between mining companies and their stakeholders and the importance of corporate citizenship policies to reputation and hence to corporate sustainability. The findings of the first stages of this research, the results of a focus group and an expert opinion survey into the drivers of reputation for mining companies are reported. This study was undertaken to provide an understanding of the drivers of reputation for a number of stakeholder groups and the perceptions held by mining companies of these drivers for their stakeholder groups. Results indicate that drivers vary between stakeholder groups - that in the case of drivers common to a number of stakeholder groups they may vary in their importance across the groups, and that there may exist a divergence between industry?s perception and stake-holders? priorities. These results further the understanding of the relationship between corporate citizenship and reputation in the mining industry, thus assisting companies to strategically manage their corporate citizenship investments and assisting them in their transition to sustainable development.

Jan 1, 2007

By Victor F. Hollister

This section describes two exploration models currently used in the search for porphyry exploration deposits: the hood and the vertical cylinder. Each has alternate names within industry and in the literature. The hood is also known as the Climax or Henderson and the vertical cylinder has also been called the Mt. Pleasant model. The paper by Hollister (1978, abstract herewith) refers to the vertical cylinder as the zoned model in reference to the horizontal sulfide and silicate zonation evident in and peripheral to the vertical cylinder of molybdenite mineralization. The distinct ore body geometry in each model type necessitates differing drilling and exploration strategies. Drilling for a hood shape is clearly different from drilling for a vertical cylinder type target. The paper by Wallace et al. (1968, abstract herewith) on multiple intrusion and mineralization at Climax, CO, well describes the hood model. That description is supplemented by the paper by Wallace et al. (1978, abstract with Chap. 37) on the geology of the Urad and Henderson deposits. The paper by Hollister (1978, abstract herewith) describes the vertical cylinder model.

Jan 1, 1991

By Walter J. Pachucki

Mining equipment maintenance costs account for a major portion of a mine’s total operating expense. A reduction of maintenance costs while providing required equipment availability translates directly into increased profit for a mine. Therefore, having in place a successful maintenance program can be management’s most direct route to increased profits. One key element of a successful maintenance program is a practical and effective recordkeeping and information system. In recent years, many mining operations have invested in the development or purchase of computerized maintenance information systems. Computerized maintenance information systems can serve as a valuable tool in managing mining-equipment maintenance. They can also be a costly, frustrating waste of time. Why are some systems successful at one operation but a failure at others? Should all mines use computerized maintenance information systems? How does management decide what maintenance software is best for their operation? In an effort to to answer these questions and to better understand what is required to make a mining maintenance information system successful, a study was recently conducted on maintenance information systems used in the mining industry.

Jan 1, 1991

By Landy A. Stinnett

Coal mines in the United States are the most productive in the world in terms of efficient labor employment. This is because of an abundance of workable coal beds, large infusions of capital, improved management practices and continuing competitive pressures. The standard unit of measurement for labor productivity is expressed as tons/manshift, although for underground mines, operators often refer to tons per machineshift. Articles written concerning labor productivity generally focus on measurement techniques, safety considerations, application of technology and training. This article will illustrate by example the impact of labor efficiency (or inefficiency) on the ultimate selling price of coal, f.o.b. mine site. During the past several years, the coal industry has seen significant improvement in labor use. Figure 1 shows the trends in productivity for all active mines in the United States from 1985 through 1994. Productivity in 1985 was 20.1 t/manshift (22.1 st/ manshift). This factor has increased almost linearly throughout that period to 37.5 t/manshift (41.2 st/manshift). This is a 7.2% annual compound growth rate.

Jan 1, 1995

By G. I. Karydakis

Geothermal energy is an important energy asset which can play a significant role in providing energy resources to cover energy needs of a country while it can play a primary role in a particular region where it is abundant. Greece is especially rich in geothermal energy. The collision of Euroasiatic and African plates coupled with the strong tectonic tension, particularly in north Greece, resulted in the formation of important geothermal fields of low, medium and high enthalpy. These fields are in the Aegean islands, in central and east Macedonia, in Thrace and in central Greece. This work presents and analyzes information about the drilling activity for exploration and production of geothermal fields of low, medium and high enthalpy in Greece for the past thirty years. The number and type of wells drilled together with the spatial and the yearly distribution are given. Depth data has been analyzed according to the fluid temperatures and to the geological formations. Cost data are presented and analyzed for the total number of wells drilled giving also the cost per meter drilled.

Jan 1, 2006

By W. R. Dengler

In Canada, most of the rock being broken in underground metal mines is being done by using traditional drilling and blasting methods. Despite advances being made in hardrock boring and other, more exotic techniques, Dynatec believes that the traditional methods will prevail for many years. It is also believed that modest research efforts expended on the traditional methods will result in substantial financial benefits to the mining and rock tunneling businesses. Dynatec has pursued productivity improvements through the use of long rounds in shaft sinking and lateral development. The concept of longer rounds was developed by Dynatec on the Craig Shaft Sinking Project (RETC, 1991). This technology was subsequently used to sink the two shafts at Aur Resources with great success. The development of a Long Round Jumbo for tunneling is a natural progression of the long round technology developed for the Craig Shaft. The Dynatec Long Round System has been patented in the United States and South Africa, with additional patent applications pending in Canada and Australia.

Jan 1, 1993

By James J. Snodgrass, David E. Siskind

The Bureau of Mines investigated the effects of vibrations from underground blasting in four rock types to define blast parameters that affect vibration amplitudes and to establish means of predicting expected vibration levels. Previous studies of surface blasting indicated that charge weight per delay period had a major influence on vibration amplitudes. Dividing the distance from the blast by the square root of the charge weight scaled the effect of various charge weights, however, and allowed vibration data for a particular site to be represented by a propagation equation of the form v = K(D/W ½ )-n (1) where v = particle velocity, D = distance from the blast, W = maximum charge weight per delay period, and K and n = empirically determined site constants. For square-root scaling, particle velocity and acceleration data from the underground sites appear to follow a similar propagation law. The subsurface data are in good agreement with those of the surface studies and provide a basis for engineering estimates of vibration amplitudes in many different rock types.

Jan 1, 1974

By T. C. Rao, Vanangamudi. M., J. P. Barnwal

Experiments were carried out on 76 mm laboratory heavy medium cyclone treating -2.0 t 0.5 mm coal and on two 600 mm industrial heavy medium cyclones treating coal in the size range -13.0 t 0.5 mm. The variables studied were spigot diameter and feed medium gravity. The generalised distribution curve for the separation of coal in these heavy medium cyclones has been defined by the equation [ ] The specific gravity of separation SG has been found to increase linearly with increase in feed medium, gravity (SGf). The relationship for SG of industrial cyclone is given as 50 SG = -6.801 t 6.463 SGf t 0.0327 Spig 50 -0.02625 SGf. Spig. Further, the probable error for the separation has been found to be linearly related to (SG50 - SGf ) according to the equation [ ] The model equations developed have been used to select appropriate levels of operating conditions to achieve an increase in the yield by about 2 to 4% without affecting the quality of the product.

Jan 1, 1990

By Howard A. Jongedyk, Jerry Wachtel

Advancements in tunneling technology and underground construction, plus rapidly rising costs of land, and a higher priority being placed on urban esthetics, make tunnels a more attractive option for certain portions of the highway construction program. Recent emphasis placed on fuel conservation reinforces the need for tunnels as a means of shortcutting circuitous routings designed to avoid potentially undesirable environmental impacts on any given area. Larger and more complex tunnels which have been constructed in recent years attest to this greater interest. More than 100 major highway tunnels are in operation in the United States. Highway tunnels commonly have much higher initial cost compared to surface routes. Where extensive cut and cover is involved, temporary disruption of the surface area may prove costly. In exchange for these costs, certain environmental advantages result. The purpose of this paper is to discuss some of the environmental advantages of highway tunnels and some of the unsolved problems related to obtaining maximum use of highway tunnels and research underway to help solve these problems.

Jan 1, 1974

By Ivano Andreis, Giovanni Valent

The Yindaruqin Irrigation Project is designed to irrigate 57,000 ha of land in the central part of Gansu Province of People&apos;s Republic of China. Water for the Project will be diverted through an 87 Km long feeder canal which will convey 36 cubic meters per second from an intake on the Datong River. (Fig. 1) The feeder canal consists of approximately 10 Km of open channels, 75 Km of tunnels and 2 Km of siphons and aqueducts. This is the biggest self-flowing irrigation water control project in the Northwest of China and it is among the most interesting projects in China for the geological and environmental conditions. Nearly half of the investment in the Project is a World Bank Loan and contractors were chosen by means of international bidding. The Italian Company, CMC Ravenna, succeeded in answering the bidding for the construction of tunnels 30A and 38, perhaps the most difficult in the Project, submitting a TBM alternative to the conforming drill and blast contract recommendation.

Jan 1, 1993

By D. Krzyszton, P. Czaja

Mining explosions in rocks originate stress waves of great intensity, which crush the surrounding rocks and are then propagated as a seismic wave. Seismic waves are the cause of dynamic loading of pillars and their subsequent destruction. In calculating safe dimensions for inter-room pillars, not only the stresses conditioned by overburden pressures should be taken into consideration, but also the dynamic stresses caused by explosion. This is of particular importance for pillars with great specific acoustic impedance which have been destroyed mainly by the reflected seismic wave. It is possible to take dynamic loading into consideration in the calculation of pillars when the parameters of the propagation wave, the dynamic elastic constants of rocks, the strength properties of rocks, the strength properties of rocks subjected to dynamic loads and the parameters of the blasting charge are known. An example of the calculation for the safe width of an inter-room pillar subjected to the seismic effect of an explosion is given and the possibilities of reducing the dynamic loading of pillars are discussed.

Jan 1, 1982

By J. Stachurski, N. A. Abdel-Khalek

The objective of this investigation was to compare the results of countercurrent, column cell flotation vs. conventional (mechanical) cell flotation for the cleaning of a sulfur ore (-0.5 mm, 27.43% S) and its discrete size fractions. The tests were carried out using diesel oil as a collector and alcohol as a frother. Generally, column flotation produced concentrates of higher grade. For example, column cell flotation produced a nonwashed concentrate of 65.3% S with a recovery of 84.1%. However, conventional cell flotation produced a rougher concentrate of lower grade (57.0% S) and higher recovery (92.5%). At a superficial-wash water velocity of 0.265 cm/sec, the column product grade increased to 76.4% S, with a slightly lower recovery (80.3%). However, a concentrate with a similar recovery but a lower grade (74% S) than that of the washed product was obtained after three cleaning stages with the conventional cell. The column gave superior results for the flotation of fine and ultrafine particles.

Jan 1, 1994