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By E. De Souza

Rockbursts and rockfalls cause very large safety and productivity losses in underground mines. One of the major unsolved problems of safe, economical rock support in underground mining has been that of maintaining anchorage during dynamic rock loading conditions or seismic related occurrences. It is recognized that the large displacements and high strain rates in excavation walls and underground structures cannot be countered by increasing the strength of stiff rock-reinforcing systems but must be accommodated by introducing yieldability into the support elements. This paper introduces a low cost yieldable support system which provides viable solutions to dynamic support loading. Such system should not only provide a feasible and more effective rock mass stabilization strategy but improve mine safety and reduce losses.

Jan 1, 1998

By T. W. Eddy

Research was conducted in which elemental mercury and its sulfide mineral (cinnabar) are removed from a copper sulfide concentrate by low temperature thermal applications. The goal of this research was to reduce, volatilize, and collect mercury vapor from concentrated smelter feed in a simulated drying environment while maintaining the chemical integrity of the residual. The study used synthesized concentrates composed of copper sulfide and mercury bearing minerals (such as cinnabar (HgS) or elemental mercury) to determine optimal residence times and temperature ranges.

Jan 1, 1996

By M. A. D. Azevedo

The effect of pulping reagents on the flotation de-inking of laser printed wastepaper was investigated with regard to the removal efficiency of toner and mineral filler particles for different pH values. These results show that caustic pulping causes the toner to be released from the fibers at larger particles sizes. On the other hand, acid pulping not only causes the toner to be released at smaller particles sizes but also increases the concurrent flotation removal of mineral filler particles. It was experimentally observed that the froth generation and stability during flotation were improved for acidic pH values.

Jan 1, 1997

By F. Mauviel, J. Bernard, G. Herrouin, J. P. Lenoble, C. Charles, B. Taine

Manganese nodule projects were quite fashionable during the 1970s. At the beginning of the 1980s, low metal prices led to an almost complete reduction of such activities; however, the Law of the Sea incited the countries that signed it to build a strategy for this ocean resource. Gemonod was created in France in 1984 with a four-year mission. This paper presents the results of its program devoted to the technical and economic studies of nodule exploitation. A commercial mining system is presented. The nodules would be collected by a self-propelled miner and lifted hydraulically through a rigid pipestring. A complete optimized scenario has been built taking into account offshore mining, ore transfer at sea, transportation and processing to analyze the profitability of the project. Considering an average conservative basis for metal prices, after a deep analysis of the market, the return rate of investment of the project appears fairly interesting. These results are new and are explained in comparison with previous foreign studies. These results must not hide the innovative nature of the project nor the associated risks. This is why a mining pilot is required and has been specified by Gemonod.

Jan 1, 1991

By Charles E. Glass

As partial implementation of the Surface Mining Control and Reclamation Act of 1977, the Office of Surface Mining (OSM), Department of Interior, has requested each state to inventory hazardous abandoned mining areas within their boundaries. Primary interest is in such areas .as unstable waste-banks, subsidence and slumping, contamination of water supplies, and preservation of overall aesthetic qualities through reclamation. In addition to the concern expressed for abandoned mining areas, the legislation requires a complete inspection of operating mines quarterly and a partial inspection monthly. In Arizona copper has been mined for over 100 years and coal and uranium mining promises to expand in future years. The OSM requirement for a waste inventory and frequent monitoring of Arizona's large, widely spaced mines places a severe demand on limited personnel and operating budgets. Remote sensing by satellite provides an attractive and effective approach to aid the inventory and monitoring requirements of the OSM legislation.

Jan 1, 1979

By Mike Amick

As virgin coal reserves dwindle, more and more mines are being opened in areas with previous mining. As addressed in this conference before, there are solutions available for designing mines extracting coal from reserves with known underground workings above or below the target seam. Often times, however, mining begins with limited knowledge of the underground workings. Even with careful planning, the proposed design has limited success because the ?facts? as presented during planning turn out not to be as accurate as one would like. At National Coal?s Mine #14, mining the Walnut Mountain seam, after driving the main entries in some 34 crosscuts, it was found during routine mine examinations that the pillars had separated from the roof in a few areas of the mains. Immediate roof conditions proved to be sound but questions arose concerning the stability of the main roof and floor. Core tests were done to better determine the rock strengths and characteristics. The paper presents the ideology used to tackle the effects of mining over old works in an operating coal mine. This paper discusses the analysis of the symptoms observed and the steps taken to ensure that this pillar separation was caused by the underlying old workings and that the separation was expected and controllable.

Jan 1, 2009

By M. J. Ross, D. A. Norrgran, J. A. Wernham, J. N. Orlich

INTRODUCTION Laboratory testing for magnetic concentration circuit design is a requirement, just as it is for most other types of concentration. Natural variations in raw materials allow on1 y the broadest of generalities to be made regarding magnetic separation. Further, magnetic fields are geometry dependent, leaving fundamental models of a separator overly dependent upon the exact conditions for which the models were derived. Despite this, an understanding of the basics of magnetic separation and of the problem to be attacked can result in rapid progress towards the final circuit design with a relatively simple testing program. Magnetic Separation Basic Principles A magnetic field can readily be understood in terms of lines of flux. A familiar demonstration of these lines of flux is the pattern of iron filings on a sheet of paper when a magnet is placed underneath. Lines of flux2 are measured in Gauss (1 line/cm2) or Tesla (10000 gauss). Regions of high field strength have a greater number of lines. Field direction is indicated by a convergence of lines. When a particle is placed in a magnetic field it cuts the lines of flux and alters them in one of three basic patterns. These patterns are referred to as diamagnetic, paramagnetic and ferromagnetic. Diamagnetic materials have electronic structures which react to oppose an applied magnetic field. This opposition acts to locally reduce the applied field slightly. The visualization is that lines of flux diverge and go around the particle. Because of this divergence or opposition, a diamagnetic particle will tend to move towards regions of lower flux density. That is to say that the particle will be repelled by a magnetic field. Aluminum oxide and napthalene are examples of diamagnetic materials. Paramagnetic materials have an electronic structure which increases an applied magnetic field. Although these materials also exhibit diamagnetism, they have randomly oriented impaired electrons which align with the magnetic field. The resultant local field enhancement is significantly larger than the diamagnetic opposition. The visual-

Jan 1, 1986

By Hans von Michaelis

Gold metallurgy has advanced remarkably over the last decade. Even more significant progress will be made over the next five years, particularly in the application of advanced comminution techniques and control, preconcentration (flotation, ore sorting and coal gold agglomeration), enhancement of cyanide leaching technology, non- cyanide leaching, treatment of refractory ores and concentrates, and improved recovery systems. Carbon adsorption processes have become standard practice for ores with relatively high gold/silver ratios, but ion exchange potentially offers distinct advantages and has recently been demonstrated to perform better in at least one application. Even in the established zinc precipitation and CIP processes several important practical improvements are emerging as experience is gained at the ever increasing number of operating plants. Improved process control and reduction of reagent consumption costs are two important goals of industry at this time.

Jan 1, 1989

By G. A. Kordosky

The literature contains several references to the influence of copper solvent extraction reagents on crud formation, but, there is disagreement as to whether the reagent has an influence on crud generation. The results of three pilot plant campaigns, where crud generation was studied as a function of the copper solvent extraction reagent, are reported. These pilot plants were run at operating copper solvent extraction plants using the aqueous solutions being treated by the commercial copper solvent extraction plants. Two of the pilot plant studies showed that the copper solvent extraction reagent had a significant influence on the extent of crud formation while the other pilot plant study indicated the copper solvent extraction reagent had a lesser influence on crud generation.

Jan 1, 1996

By Preusse. Axel

Underground coal mining can cause seismic events. There is currently no way to predict such phenomena reliably, in particular stronger events. That is why, according to the current state of the art, empirical methods are employed in this field. Some assessment criteria, which relate to the geological and mining situation and either stimulate or rather help to avoid seismic events, are presented in this paper. These criteria are examined for a practical mining situation in Germany, with a view to estimate possible seismic events.

Jan 1, 2009

By Robert M. Belesky, H. R. Hardy

A methodology to detect the presence and monitor the stability of shallow cavities is presented in this paper. The approach incorporates surface-wave seismic and acoustic emission/microseismic (AEIMS) techniques. Application of tomography to the seismic data is made to enhance the ability to locate cavities. Zonal and hit-sequence location techniques are introduced into AE/MS monitoring schemes. These source location techniques simplify the analytical procedure yet still provide sufficient information regarding the region of AE/MS activity. The concept of unique velocity data for conventional, least-squares, source location routines is discussed. A hypothetical case utilizing the algorithm is presented. The method described has been successful based on preliminary studies. Areas of current and future research are identified.

Jan 1, 1986

By J. Ye

A comprehensive flotation study has been carried out on a Chinese fluorspar ore using the packed flotation column developed at Michigan Technological University. The results are compared with that of a conventional mechanical flotation method on the same feedstocks. Key factors controlling flotation performance of both methods are evaluated based upon a simple statistic design. The flotation concentrate produced in one stage of the packed column has 4-S% higher recovery and much lower silica impurity content than that produced by up to six stages when a conventional mechanical cell is used. The results also show that the packed column flotation process is particularly suitable for recovery of finer fluorspar particles.

Jan 1, 1992

By K. J. Shoop

This study investigates the use of a horizontally-baffled column (7.6 cm inside diameter by 344.2 cm high) to reduce the ash content of a high ash bituminous coal. Tests were carried out to determine how the baffled column responded to changes in feed rate, reagent dosage, and feed quality, and to compare its performance with a conventional column installation in an operating plant. In this paper, the results of this investigation will be reviewed and discussed.

Jan 1, 1997

By Keith G. Wallace

In 1982 the U.S. Congress passed the Nuclear Waste Policy Act (NWPA) to provide for the development of an underground repository for spent nuclear fuel. This development will be managed by the United States Department of Energy. In 1986, the President selected three areas for site characterization to determine their suitability for the development of an underground repository; those sites were: 1) A site in volcanic tuff located at Yucca Mountain in Nevada, 2) a site in bedded salt located in Deaf Smith County in Texas, and 3) a site in basalt located in Hanford, Washington. At present conceptual repository designs are being developed for each site. A key element of a repository design is the underground ventilation system required to support construction, nuclear waste emplacement, and potential waste retrieval. This paper describes the preliminary ventilation system designed for the repository in tuff. The concept provides separate ventilation systems for the construction and waste emplacement activities. The paper further describes the means by which acceptable environmental conditions will be re-established to allow re-entry into previously closed rooms for the purpose of inspection, maintenance or retrieval.

Jan 1, 1987

By William H. Langer

Nearly every community in the United States is dependent on aggregate (sand, gravel, and crushed stone) resources to build and maintain its infrastructure. Unfortunately, developing aggregate resources to meet societal needs causes environmental impacts. Most environmental impacts associated with aggregate mining are benign. Extracting aggregate seldom produces acid mine drainage or other toxic effects commonly associated with mining of metallic or energy resources. The most obvious environmental impact of aggregate mining is the conversion of land use, most likely from undeveloped or agricultural land use, to a hole in the ground. This major impact is accompanied by loss of habitat, noise, dust, blasting effects, erosion, sedimentation, and changes to the visual scene. Some of the impacts are short-lived, and most are easy to predict and easy to observe. Most impacts can be controlled, mitigated, or kept at tolerable levels and can be restricted to the immediate vicinity of the aggregate operation by employing responsible operating practices and available technology. The intensity of environmental impacts generated as a result of mining are determined in large part by the geologic characteristics of aggregate deposits (geomorphology, geometry, and physical and chemical properties). Mining deposits that are too thin, or contain too much unsuitable material, results in the generation of excessively large mined areas and large amounts of waste material. Mining aggregate can lead to serious environmental impacts in some situations. Some geologic environments such as active stream channels, slide-prone areas, and karst terrain are dynamic and respond rapidly to outside stimuli including aggregate mining. Some geomorphic areas and (or) ecosystems underlain with aggregate serve as habitat for rare or endangered species. Similarly, some geomorphic features are themselves rare examples of geologic phenomena or processes. Mining aggregate might be acceptable in some of these areas, but should be conducted only after careful consideration, and then only with extreme prudence. Failure to do so can lead to serious, long-lasting, and irreversible environmental consequences, either in the vicinity of the site or at locations distant from the site. Environmental impacts caused by irresponsible aggregate mining can compromise mining in an entire region.

Jan 1, 2001

By C. I. Basilio

The adsorption of dialkyl di-and mono-thio-phosphinates on gold, silver and gold-silver alloys has been studied in the present work. These reagents, which are selective collectors for sulfide flotation, have been found to improve precious metals recovery from ores. Voltammetric studies have indicated that dithiophosphinate adsorbs on gold at much higher potentials than on silver, while monothiophosphinate adsorbs only on silver. However, both adsorb on gold-silver alloys with the adsorption potential decreasing with increasing silver content. Using FTIR spectroscopic measurements, the surface species formed during the interactions of these collectors have been identified. The results of the electrochemical and spectroscopic measurements have been compared with the contact angle data obtained at controlled potential conditions.

Jan 1, 1992

By L. A. Henry

The island of Jamaica consists predominantly of Carbonate rocks which vary in chemical & physical characteristics. Currently these rocks are used for construction and road aggregate, landfill and as a raw material in the manufacture of cement. Over the past fifteen years the Geological Survey of Jamaica with assistance from a number of international aid agencies and the private sector have identified deposits of high calcium/high brightness limestones which have the potential to be utilized as a high quality filler and a number of other commercial applications. Geologically, these limestones are formed within the Eocene Swanswick Formation, the Oligocene Walderston-Browns Town Formation and to a lesser extent the Miocene Montpelier and Newport Formations.

Jan 1, 1998

By Stephen C. Tadolini, Thomas M. Barczak

Western mines have had limited choices for standing support. Wood cribs were often too soft and unstable. The introduction of the Can support in the early 1990’s provided a very effective alternative and remains the dominant form of tailgate support. Water-filled prestressing cells are now used to cap the Can and preload it to provide an active roof load. The Cluster Prop, consisting of three timber wedge props bundled together, provides more capacity than an equivalent sized Can support and improves transport efficiency. However, the Cluster Prop is less stable and does not maintain a consistent load throughout its loading profile. Pumpable roof supports are another alternative support, but they have not been proven in high deformation environments. Alternative supports are also being used in longwall recovery operations. These include the Rocprop and Omni Prop, which are extendable support systems. They also provide active roof loading which can be beneficial in these applications. Specialty supports, such as the Sand Prop and Spider Prop, have also been introduced into western longwall operations. This paper compares the performance characteristics of these various support systems.

Jan 1, 2005

By Don Runge, John T. Zeni

Cuprex Limited is currently developing a small gold mining operation in Central Australia in the Tennant Creek field. In February 1984, the company undertook a feasibility study on the project and operations commenced in August 1984. Ore reserves are located between 230 and 280 metres (755 ft and 919 ft) below surface and ore extraction required the establishment of a shaft network for access, ore hoisting and ventilation. Zeni Drilling Company from West Virginia, U.S.A. was contracted to blind drill two shafts for the project. Blind drilling was selected for various reasons, including timing which related to cost efficiency. The blind drill shaft technique has proved successful in this application and with enthusiastic and innovative support from the mining industry, will prove an efficient and cost effective means of accessing and operating underground mining projects of all sizes in the future.

Jan 1, 1987

By D. Morin, J. Villeneuve, S. Foucher

The development of new processes has to follow "best practice" rules in order to be technically and economically as efficient as possible. However, innovations, new process routes and new rules are continuously emerging to minimize financial risk and maximize environmental compliance. Process simulation, which offers a complete overview of the flowsheet, makes it possible to cope with this new challenge-minimizing waste production and water consumption. Furthermore, simulation provides an estimate, at the early stage, of the cost of alternative technical routes. Four examples involving biotechnological circuits are presented, both at the design and commissioning stages.

Jan 1, 2000