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By M. Bidart, V. Sawyer, M. Saunders Macdonald

A number of open pit gold mines in Nevada extract ore from areas that are below the natural groundwater elevations. This necessitates dewatering, which requires a method for the disposal of the extracted water. Some of these open pits extend well below, the water table with dewatering volumes greater than 10,000 gpm (38,000 L/min). Some mines with large volumes of dewatering water have constructed reinfiltration basins to reintroduce the water into the groundwater system at a point some distance from the pits. This paper presents an overview of the state of the art of reinfiltration projects, including the permit process for such projects in Nevada. The paper includes the necessary engineering considerations.

Jan 1, 1997

Continuous improvement has become the watchword of the 1990s for most iron-ore-processing operations. In many instances, this improvement has been achieved through stepwise application of advanced control techniques to optimize operations. The benefits of this stepwise application have been great. However, they have fallen short of the full potential offered by the prospect of overall plant optimization. The successful integration of computers, instrumentation and control software throughout a plant promises to deliver an additional 3% to 5% of productivity in even the best-run plants (Herbst and Bascur, 1984). LKAB is Europe's largest iron-ore producer and a leading implementer of advanced control technology. In the late 1980s, LKAB introduced advanced control in its concentrator at Kiruna, Sweden to improve plant performance through higher productivity, greater efficiency and lower costs at each processing step.

Jan 1, 1995

By Colin M. Kelly

The Loveridge Mine, located near Fairmont, West Virginia, has been mining coal from the Pittsburgh Seam since 1958. As the mine develops its reserves it finds itself with increasingly distant hauls from the operating faces to the preparation plant. Initially, the mine was designed with track haulage. The coal was hauled to an underground rotary dump which fed a slope belt, to the preparation plant. As the haulage distances increased, production delays due to the track system's limitations became severe. To resolve this situation, a complete review of the haulage system was undertaken. Simulations of the present system along with future scenarios were conducted to help management effectively plan the haulage requirements of the mine for the remainder of its life.

Jan 1, 1986

By Boris M. Vorobjev

The paper in question discusses a wide range of topics related to computerized coal mine monitoring systems starting with the history of development and application of computerized monitoring coal mine systems and finishing with modern trends in the design and updating of such systems. The paper focuses exclusively on methodological and technical aspects of computer-based coal mine monitoring systems and their applicability in both surface and underground coal mining operations.

Jan 1, 1989

A number of factors affecting the properties of cemented aggregate fill (CAF), particularly its strength development have been studied through a series of laboratory investigations carried out at the Western Australian School of Mines in the Western Australia in recent years. The outcomes of these investigations indicate that apart from cement dosage, aggregate particle size distribution, aggregate quality, additional fine materials, water salinity, admixture dosage and sample scaling all contribute significantly to the development of cemented aggregate fill strength.

Jan 1, 2001

By W. D. Mayercheck, A. G. Mayton, J. R. Bartels

Since 1982, the US Bureau of Mines has investigated improvements in protection for operators of thin seam shuttle cars. Due to working height restrictions in thin seam mines (=1.22 m or 48 in.). Federal mine regulations require that canopy protection on shuttle cars be provided only in mines =1.07 m (42 in.). However, court obtained variances are granted to mines =1 .22 m (48 in). This paper presents ongoing research to design and evaluate a uniquely positioned, ergonomic compartment for a shuttle car that provides the operator with full canopy protection in working heights of 1.02 m (40 in.).

Jan 1, 1990

By R. Sripriya, Ch. V. G. K. Murty, N. D. Rao, P. V. T. Rao, A. Ramu

Studies were carried out to improve the performance of hydrocyclones at Tata Steel's chrome ore beneficiation plant in Sukinda, India. The optimal cut point of the hydrocyclones was determined in the laboratory using a stub cyclone. In the tests, the operating and design variables, including spigot diameter, density of feed slurry and inlet pressure, were varied. Subsequently, plant trials were carried out, and attempts were made to develop a model of the hydrocyclone using the Rao, Lynch and Plitt model. The cyclone efficiency was represented by the parti¬tion curve, and the performance was evaluated mathematically from a reduced efficiency curve, represented by the equation:

Jan 1, 2000

By J. Partyka

Fumes produced during blasting operations in underground mines are defined in this paper by an equivalent contaminant source. The primary goal is to establish a method which would allow all those parameters not measured directly to be determined reliably from field data. The parameters to be identified are the diffusion coefficient , and the position and size of an equivalent source. The diffusion-value is computed from the peak concentrations taken by two monitors located in the drift. The first monitor is placed close to where blasting pollutants join the main stream, while a second monitors is moved downstream a some distance from the first point. The position and size of the dust source and the total amount of dust produced during blasting are determined from the data recorded by only one monitor.

Jan 1, 1991

By C. R. Jenkins, G. S. Taylor

Three sedimentation ponds had their performance evaluated before and after installation of modifications. Each pond had a floating baffle installed, two had siphon outlets, and one had a floating outlet device. Baffles inhibited short circuiting, and the outlet devices retarded flow following a rainfall event and drained the pond, creating a large storage volume to maximize detention time. Total suspended solids and settleable solids tests were measured on samples of influent and effluent to evaluate pond performance. Particle size analyses were conducted on samples containing measurable amounts of solids. Performance improved in each pond, with baffles providing the major improvement.

Jan 1, 1987

By Jozef Szymanski, Julian Partyka, Jerzy Krynicki

In order to study blast-induced dust in a hard rock metal mine experimentally and analytically, a part of a stope mined by Vertical Retreat Mining (VRM) was monitored throughout its lifetime. Dust measurements were used to describe the dust source, to study the dynamics of removal of airborne dust from the blasting area, and to examine a variation in dust production with a stope's progress. An analysis based on graphical and analytical comparisons of blasts taking place in a single stope is presented and discussed. Also, some transient phenomena of dust flow in the stope vicinity, caused by the blasts only, are examined.

Jan 1, 1997

By Anna Arkhireeva, John N. Hay

Considerable interest has been shown recently in organically modified silicates (ormosils) because of the wide range of possible applications for these interesting organic-inorganic hybrids. These applications include the use of the hybrids as modifiers of a range of host polymer proper- ties. The ormosils can be synthesised by the conventional hydrolytic sol-gel process, as well as by the non-hydrolytic sol-gel route. To date, however, there are relatively few reports of the synthesis of sub-micron size ormosil particles of well-defined spherical morphology. Here, we report work to date on synthesis of such nanoparticles and also introduce our own work in the area.

Jan 1, 2003

By S. G. Haycocks, M. Karmis, C. Haycocks

Risk assessment is a primary factor in the decision to mine some near surface orebodies, such as limestone, by either surface or underground methods. Identification and quantification of risks demonstrate that environmental concerns are greater for surface operations than underground, and may include such factors as runoff, spoil piles, aesthetics, dust, and large site reclamation. Risk assessment also includes local public feeling towards surface and underground operations while considering the balance between environmental impacts and the economic effects of mining on the local community. A complete understanding of the risks involved permits a comprehensive and accurate comparison between the two mining alternatives.

Jan 1, 1992

By G. A. Dawe, E. G. Kelly

Because of the nature of the breakage in the Barmac vertical spindle impactor, the 80% reduction ratio is very small, so that when an energy efficiency is calculated from Bond's method, it appears to be very low. However, the product size distribution contains a high proportion of fines. It is argued that the production of these fines accounts for the high energy consumption, and Bond's method is modified to account for this, by considering the crusher to be, effectively, a number of smaller crushers in parallel, each having a different reduction ratio.

Jan 1, 1990

By James A. Brierley, Rong Yu Wan

Bacterial pretreatment was evaluated as a process for enhancing gold recovery from a refractory ore from Newmont Cold's Cold Quarry deposit. This ore is refractory due to sulfide locking of the gold and preg-robbing carbon. The microbe Thiobacillus ferrooxidans effectively oxidized the sulfide component of the ore, but the preg-robbing carbon continued to be active. Thiourea was examined as an alternative to cyanide for extraction of the gold from the biooxidized ore. The thiourea, coupled with CIL, was effective for gold extraction resulting in up to 89% gold recovery for the sulfidic-carbonaceous refractory ore. The thiourea gold complex appears not to be bound by the preg- robbing carbon of the ore when in the presence of recovery carbon (CIL)

Jan 1, 1990

By S. L. Patil, D. E. Walsh

A novel form of calibration of on-line analyzers was implemented. Rather than simple equations, a neural network was used to model the relationship between the scintillation counts (Am and Cs) of an analyzer, and the measured ash for improved on-line analysis of run-of-mine (r.o.m.) coal. Also, a new approach was followed to better evaluate neural network performance. Samples were first divided into various statistically different groups using a Kohonen network. Data was then selected for the training, calibration and prediction subsets, using criteria developed in this paper for sparse data, with representation from each group. A backpropagation based neural network architecture was used in conjunction with quick stop training. Due to noise in the data, the predictions were very good on average, but not individually.

Jan 1, 2003

By Qiang Ji, Richard L. Sanford

A laboratory-scale microcomputer-based autonomous excavation system has been developed that moves a pile of fragmented rock to a designated location using a shovel attachment on a robot arm. Navigation and excavation sub- systems interactively direct a robot excavator to move the shovel to the rock pile, intelligently load its bucket using a video camera, and dump the rocks to a designated area. Although research was conducted on a laboratory scale model, the system can serve as the basis for further work on a full-scale, robust excavation system.

Jan 1, 1993

By Gordon R. Wicker, John A. Cole

Although the evaluation of autoclave oxidation for Getchell ore was begun nearly 40 years ago, its ultimate implementation in 1989 represents the first substantial improvement in the economics of processing this refractory ore. Sulfide ores at Getchell were previously roasted prior to leaching (in the 30's and 60's), resulting in somewhat lower recoveries than are currently realized by autoclave oxidation. Recoveries on the order of 90% are expected from the high-arsenic sulfide ore over the expected 10-year mine life.

Jan 1, 1990

By P. R. Hervey, J. W. Foise

Quartz is the second most widely used electronic material, with approximately 3,000 t (3,300 st) of single crystals used each year. Most of the quartz used in electronics is synthetic and is manufactured using a technique called hydrothermal growth. This paper reviews the basics of hydrothermal growth, the feedstocks used for these crystals and the challenges to improving the growth process. This paper also reviews the processing of these crystals, the markets and applications where they are used, and the global outlook for these markets.

Jan 1, 2002

By V. K. Karra

Based on extensive investigations on the effect of design variables on process performance from 1982-85, Nordberg developed a 746 kW (1000 hp) cone crusher with the objective of boosting crushing productivity in existing plants. The MP1000 fits on the same foundation as the 2 m (7 ft) SHD Symons cone but is designed to give two times the capacity of the 2 m (7ft) The economies of scale involved give the customer substantial cost savings. In this paper, process performance of the Nordberg MP1000 relative to the 2 m (7 ft)SHD Symons cone while crushing the same ore, will be presented. Also, implications of such a crusher scale-up to associated cost savings will be addressed.

Jan 1, 1990

By G. V. Basham

"Environmental audit" is a phrase that can raise the blood pressure of otherwise cool and calm corporate personnel. There is widespread concern that any organized effort to find environmental problems will do so and may result in the imposition of substantial liability against the business that engages in such activities. However, such audits can reduce rather than enhance possible liability. Relevant issues include: the role of the attorney in the process, liability risks associated with environmental audits, steps to maximize confidentiality of audit results, reporting requirements and use of audit results in a proactive manner.

Jan 1, 1995