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By A. G. Sciulli, G. P. Ballock, G. Hearnshaw, K. K. Wu

Waste disposal underground is the most effective method when viewed from an environmental aspect. As costs of other methods of disposal continue to escalate, the cost effectiveness of underground disposal during the mining cycle becomes increasingly attractive. The use of concrete for sealing abandoned mines has proved to be suspect when associated with a relatively incompetent adjacent strata due to its shrinkage characteristics. Complete failure of the plug has been known to occur in some instances. A more effective, cost competitive seal can be obtained using pneumatically stowed material and incorporating a polyurethane grout, which has greater adhesion characteristics than concrete. Injection of the surrounding strata and of the stowed material helps to ensure an impervious barrier and prevent the plug from moving when subject to high pressure heads. When properly placed, impervious seals cause the old workings to flood, raise the mine pool level, and thus eventually eliminate the potential for oxidation, which is the primary cause of acidity in the water

Jan 1, 1987

By J. P. Mogan

As diesel exhaust contains a mixture of several materials of varying degrees of toxicity which interact to a currently undefined extent in their effects on health, the prescription of a quantity of ventilating air to dilute the exhaust to a safe level is necessarily, to some extent, arbitrary. Some jurisdictions rely on the application of a safety factor to a single "governing" component (usually nitric oxide for most modern diesel engines). Others specify that the total of the "adjusted" concentrations (actual concentration divided by maximum permissible concentration) not exceed "one" for related constituents (irritant gases for example). Neither of these approaches, however, takes account of the interaction of the gaseous constituents with diesel soot (although many studies verify such interactions), nor do they provide any economic incentive for reducing pollutants which are not included in the criteria for ventilation. Because of these factors, the Canadian Department of Energy, Mines and Resources awarded a contract for a study of the current literature bearing on the "Health Implications of Exposure of Underground Mine Workers to Diesel Exhaust Emissions" (1). One goal of this study was the formulation of a new ventilation criterion. The contractors, Ian W. French and Associates, studied more than 1500 literature citations which they interpreted in a 350 page report and summarized in a companion 1600 page annotated bibliography. In the recommendations section of the report, they defined a new 'health effects index' or ventilation criterion "V" as follows: [ ] The contractors consider that a "V" between 3.0 and 4.0 poses a moderate threat to health which could be alleviated by the use of protective equipment such-as filter helmets. If V exceeds 4.0, an increase in ventilation quantity to reduce the pollutant levels is indicated. In the case of mines with a quartz content in excess of 20% in the ore, the contractor recommends that a term. [Quartz]/ [Threshold Limit Value Quartz] be added to the equation, and [2.0 = ?v? = 30] be the range justifying protective equipment, with added ventilation if "v" exceeds 3. A degree of pragmatism was inherent in the development of the equation, as the contractors recognized that the components of the index, if it is to be useful in the near term, should be within current routine underground environmental assay capability.

Jan 1, 1980

By A. G. Sciulli, G. P. Ballock, K. K. Wu

Waste disposal underground is the most effective method when viewed from an environmental aspect. As costs of other methods of disposal continue to escalate, the cost effectiveness of underground disposal during the mining cycle becomes increasingly attractive. The use of concrete for sealing abandoned mines has proved to be suspect when associated with a relatively incompetent adjacent strata due to its shrinkage characteristics. Complete failure of the plug has been known to occur in some instances. A more effective, cost competitive seal can be obtained using pneumatically stowed material and incorporating a polyurethane grout, which has greater adhesion characteristics than concrete. Injection of the surrounding strata and of the stowed material helps to ensure an impervious barrier and prevent the plug from moving when subject to high pressure heads. When properly placed, impervious seals cause the old workings to flood, raise the mine pool level, and thus eventually eliminate the potential for oxidation, which is the primary cause of acidity in the water.

Jan 11, 1986

By D. Harris, M. Osterberg

This paper examines the economics of acquiring mineral exploration rights by royalty-rate bidding when the royalty basis does not provide for full cost recovery. Bidding takes place prior to exploration and the documentation of actual tonnage and grade. Consequently, it increases considerably the risk to exploration capital when the fraction of cost recovered is small and the product price exhibits large fluctuations. Price and grade risk are demonstrated on a 360-Mt (400-million-st) porphyry copper deposit by Monte Carlo simulation of discounted-cash-flow analysis. Copper price is modeled as a stochastic price process, and costs are based on US Bureau of Mines cost models. When both grade and price risk are considered, the probability for a negative NPV is 0.54, given a royalty rate of 5% applied to a basis that allows the recovery of costs up to 50% of product price. Investment risk could be considerably reduced by defining the royalty basis to allow greater cost recovery. Although such a basis would require society to share in the risk, society would benefit from greater resource development.

Jan 1, 2000

By Victor F. Hollister

The great increase in post-World War I1 use of molybdenum was made possible by discoveries of that metal in porphyry molybdenum and porphyry copper deposits. This section documents significant porphyry molybdenum discoveries of the post-war period. The most important discovery was Henderson in Colorado. It is not only one of the world's largest and richest, but it was found by a team of geologists who defined the hood model and tested it successfully at Henderson. Under the leadership of Stewart Wallace, these scientists established a set of criteria for exploration for Henderson-type de- posits that was copied by the industry. The discovery bf vertical cylinder type porphyry molybdenum deposits was less renowned. Boss Mountain in British Columbia and then Mt. Pleasant in New Brunswick were given relatively scant notice, compared with the Henderson discovery. However, these deposits have geometrics distinct from that found in the typical hood, which directly affects their exploration characteristics. Mt. Pleasant, included in this section, is a well defined, near vertical breccia pipe. Both the Henderson and Mt. Pleasant discoveries were made by relatively small groups operating independently of the bureaucracy that characterizes large corporations. The management role in each case was one of encouragement. In addition, Wallace had the beneficial experience of working for Climax, whose objective was the discovery of porphyry molybdenum deposits. Henderson was the natural outgrowth of the exploration effort by those who studied and understood the Climax deposit.

Jan 1, 1991

By R. Woods

INTRODUCTION Gaudin (1), considered that "the mechanism of mineral collection is the central problem of flotation theory". From their work on adsorption phenomena in flotation for more than fifty years (2), Gaudin and his co-workers have made major contributions to the elucidation of this mechanism, a fact acknowledged by their contemporaries in the field (e.g. (3)). Their investigations in a number of areas, e.g. demonstrating that submonolayer quantities of adsorbed collector species can induce flotation, or identifying the influence of substances which can activate or depress (1), have helped to provide the basis for and the development of a theory to account for the interaction between mineral and collector. It was established in the late fifties (4) that the presence of oxygen is a prerequisite for the flotation of metal sulfides with thiol collectors. This fact rendered inadequate the concept of simple ion adsorption being responsible for rendering these minerals hydrophobic. The requirement for oxygen has been explained (1) in terms of this species being a component in chemical reactions between the sulfide surface and the collector. Gaudin has been instrumental in identifying the products of chemical reactions at sulfide minerals (1.5), a line of work which has been continued particularly by Finkelstein and co-workers in South Africa (6). In presenting a detailed mechanism of the mineral-collector- oxygen interaction, it has often been considered that the mineral surface - must first be oxidized to a metal oxy-sulfur species which

Jan 1, 1976

By Kalliat T. Valsaraj, Louis J. Thibodeaux

A mathematical model is described for the transfer of hydrophobic compounds from aqueous to an immiscible organic phase using fine bubble aeration; the process otherwise known as "solvent sublation" an adsorptive bubble separation process. The limitations of the model are explored by simulating experimental results both for a batch scale process and a continuous process. The qualitative predictions of the model with respect to the influence of the organic layer (mineral oil) are tested by performing experiments using chloroform and 2,3,6-trichloroanisole as hydrophobic compounds in the aqueous phase. The continuous process is seen to be limited by the requirements of fine bubble generation and the ratio of influent feed rate to air flow rate.

Jan 1, 1989

By Sundar S. Saluja

Efficient and re1iable methods of fragmentation through blasting have been sought ever since the introduction of black powder in mining operations, but the pace of investigation became faster with the discovery of nitroglycerine. The development of modern measuring instruments and the need to blast more rock with the least damage has made the study of blasting mechanics and its application more important, particularly since the oil embargo. Investigations into the practical approach evolved by Daws (1909) and the work done to make it more useful is discussed. The work of several investigators is touched upon with particular reference to the development of computer programs to simulate and optimize blasting operations.

Jan 1, 1986

By I. J. Jansen

Successful soil construction involves preparation of an adequate base, selection of high quality soil materials, and placement of those materials by means which will establish a continuous macropore network and modest to low soil strength. Where such has been accomplished, experiments reveal row crop productivity on reclaimed land which is very competitive with that on undisturbed land. Inferior productivity and sensitivity to drought stress are experienced where the soils are excessively compacted during construction. Some deep tillage practices have been quite successful in improving the compacted soils, but it is preferable to avoid compaction as the soil materials are handled.

Jan 1, 1987

By G. Camposano, J. Aponte, B. A. Ferguson

The paper covers mining operations and preparation of the ore prior to metallurgical treatment in the Process Plant. Mining operations are primarily concerned with the delivery to Ore Preparation of a balanced ore feed within fairly rigid specifications as to both ore type and chemical analysis. The mining method, systems of geological and engineering control, and the equipment employed are therefore reviewed in this context. In Part One of the paper the physical and geological characteristics of the orebodies, including the varied nature of the ore itself, are first described. Orebody evaluation, the calculation and classification of ore reserves, mining planning and forecasting to ensure continuity of production are covered, and the particular problems presented by sampling, the erratic distribution of ore values and the variation in the density of the ores are also mentioned. Mine design and ore excavation practice are described, together with the way in which they have evolved with recent developments in modern mining equipment. In Part Two of the paper, a detailed description of the Ore Preparation plant is given, centred around the concept of rubbling as a means of separation of the barren hard boulders from soft lateritic ore. Ore blending and ore reclamation operations are explained followed by a detailed description of the drying and crushing plant. The importance of the control of moisture content and ore sizing in the feed to the metallurgical plant is emphasized.

Jan 1, 1979

By Allan D. Fernie

Growing interest in pit crushing and conveying is evident from the many articles, technical papers, and new equipment development recently presented. Application of a pit crushing and conveying system is complex, as many factors such as mine design, production scheduling as well as initial and ongoing capital and operating costs must be thoroughly and realistically examined. This paper will address the fundamentals to be considered and review several approaches to developing a total system for a new and existing mine situation. The planning function will be outlined and operating and design criteria defined to interface the mining operation and the pit crushing conveying system.

Jan 1, 1983

By R. K. Mehta

A review of the literature reveals that methods for simulating the coupled behavior of size reduction and liberation are limited to binary mineral systems containing one composite particle class. The aim of this paper is to describe the development of a mathematical model to simulate such behavior for binary and ternary systems containing multiple classes of composite particles. A modified Levenberg-Marquardt algorithm and a finite difference Jacobian are used in conjunction with the developed model and a set of constrained equations to estimate all kinetic parameters. This estimation scheme is validated for a binary ore (sphalerite-dolomite) with five composite particle classes using experimental data.

Jan 1, 1989

"The use of gas, temperature and airflow sensors to monitor mine ventilation atmospheres offers numerous safety and operational bene-fits to mines. Detection of dangerous gases, changes to airflows and temperature variations are some of the obvious benefits of using at-mospheric sensors in mines. The prediction of atmospheric conditions between sensors however is potentially difficult, and gaining full cover-age a mine will require either many sensors or a method of extrapolat-ing and predicting atmospheric conditions between and downstream from a sparser array of sensors. A dynamic simulation computer model technique is demonstrated to predict time based changes to atmosphere conditions downstream from sensors. The dynamic model predicts the time based changes to conditions throughout a mine model by simulating the mixing, addition and dilution of gases and airflow changes in incremental time steps. The advantages of this method is that a real time overview of full mine atmospheric conditions can be viewed at all locations, even areas without sensors. In addition, with careful planning and consideration of potential contaminant sources, the number of required sensors can be minimized. INTRODUCTIONMine Ventilation Sensors The importance of continuously monitoring mine atmospheres has been recognised since mining underground began and the effects of harmful gases on human health were discovered. Through the 19th and early 20th centuries, coal miners would take canaries underground with them as an early detection system against life threatening gases such as carbon dioxide, carbon monoxide and methane (Figure 1). The canary, normally a very songful bird, would become agitated, stop singing and eventually die if not removed from these gases, signalling the miners to quickly exit the mine (Davalle, 2011)."

Jan 1, 2016

Asgco’s design of the Arrowhead Ceramic Lagging provides solutions to problems experienced with conveyor belt slippage around the drive pulley and severe wear problems on snub and bend pulleys. Asgco has developed a range of pulley lagging from ceramic, drive rubber and non-drive rubber lagging that is available in abrasion-resistant SBR and MSHA grade rubber for conveyor pulleys from slow belts all the way through to high-speed, high load belts. There is a growing need for a maintenance-free and reliable pulley lagging to ensure conveyor belts run to their highest efficiency.

Jan 1, 2006

By Tyler Luxner

Stillwater Mining Co. (SMC) is the largest primary producer of platinum and palladium in North America. SMC operates two underground mines in south central Montana, along the 45-km (28-mile) platinum/palladium J-M Reef in the Stillwater Complex. The Stillwater Mine exploits 9.6 km (6 miles) of deposit strike length and East Boulder Mine exploits 4 km (2.5 miles) of deposit length. The two mines are 20.4 km (12.7 miles) apart with SMC controlling a considerable length along the entire J-M Reef trace. Production at the Stillwater Mine began in 1986 and in 1988 the first tunnel boring machine (TBM) was commissioned, becoming an integral part of mine development at SMC. TBMs have been used for developing production footwall laterals (FWL) to access new mining blocks at the Stillwater Mine, as well as boring twin crosscut ac-cess tunnels at the East Boulder. Two TBM development expansion projects are currently in progress: the Graham Creek project at the East Boulder Mine, which will extend footwall lateral development 2,591 m (8,500 ft) to the west, and the Blitz project, where a TBM will be commissioned to extend east out of the Stillwater Mine to 3,658 m (12,000 ft) beyond the current production mining front. General strike and dip of the Reef is west to east and to the north, respectively.

Jan 1, 2012

By R. K. Mehta, U. Cetin

The Nevada Test Site is located approximately 100 km (65 miles) northwest of Las Vegas, NV. The site was primarily used by the Department of Energy for the field testing of nuclear weapons and has been contaminated by several million cubic feet of low-level radioactive wastes, heavy metals, explosive materials, and volatile and nonvolatile organics. The transportation and leaching of these contaminants are creating serious environmental problems. The purpose of this study is to examine pozzolan, a natural alumina-silicate mineral, as a possible replacement for the existing impermeable clay barriers. In the first phase of this study, radionuclide sorption characteristics of pozzolan were investigated. This paper presents the results of the adsorption tests for the target radionuclides.

Jan 1, 2000

By Y. J. Wang

A subsystem-based approach to the characteristic curves for a multiple fan ventilation system is presented. The ventilation variables and their relationships associated with a fan branch are considered as a subsystem of the multiple fan system. For each subsystem, the solution curve is generated by replacing the fan with a hypothetical pressure source or, alternatively, by adding a hypothetical pressure source without removing the fan. The projection of the solution curve onto the coordinate planes results in two classes of subsystem characteristic curves: pressure-vs.-quantity and quantity-vs.-quantity. The subsystem characteristic curves are described and illustrated through example ventilation systems. These curves are also discussed using the network equations of a general multiple-fan system.

Jan 1, 1993

Along with kyanite and sillimanite, andalusite forms part of the sillimanite industrial minerals trimorphous alumina-silicate group. Theoretically, andalusite contains about 60% A1203 and 40% Si02, with a Mohs hardness of 7 to 7.5 and a specific gravity of 3.0-3.2. Andalusite generally occurs in the contact metamorphic zones of schists and shales, constituting about 10% of the ground mass ore body. The 5- to 20mm- (0.2- to 0.8-in.-) long crystals are usually liberated through crushing and magnetic/heavy-media separation. Relatively minor occurrences of andalusite are found in Andalusia, Spain (where it was first identified), Portugal, the former Soviet Union, Ghana, South Korea, California and North Carolina. It also occurs in China, France and South Africa. The latter two represent nearly all the andalusite that is exported. Andalusite is an inert refractory raw material that does not require calcining before use. It involves an internal conversion to mullite after heating to 1400° to 1600° C (2552° to 2912° F). At higher temperatures of about 1800° C (3272° F), the mullite converts to corundum and liquid silica.

Jan 1, 1995

By David I. Smith, Kenneth Arnold, Bryan Aweh, Vincent Falkowsk, Brian Lakin, Andy Fer

Nassau County, New York, is undertaking several projects to improve the water quality in the Western Bays of Long Island. A major step forward will be the completion of the Bay Park Conveyance Project, which will divert most treated effluent away from the Western Bays to an existing ocean outfall at the Cedar Creek Water Pollution Control Plant. The ongoing works include 3.6 miles of microtunneling, 7 miles of sliplining, 14 shafts, and a 75 MGD pump station. This paper provides an overview of the design and an update on construction progress through December 2022. The project is a collaborative effort between Nassau County, New York State Department of Environmental Conservation, the design-builder, and various consultants.

Jun 13, 2023

By D. D. Harbuck

The US Bureau of Mines investigated germanium and gallium extraction from an ore containing 0.089% Ge and 0.036% Ga. While previous researchers concluded that a reducing agent, such as SO2 is needed to extract germanium and gallium from such ore, this research showed that high extractions (87% Ge, 97% Ga) were possible using sulfuric acid alone, if the acid concentration were properly controlled. This control was achieved using a two-stage countercurrent leach circuit. Microprobe analyses revealed that the non-extracted germanium is in solid solution with quartz, and therefore cannot be leached with SO2 or sulfuric acid.

Jan 1, 1991