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By Lee W. Abramson, Glenn M. Boyce

A dowel testing program was conducted as part of the Interstate Route H-3 Trans-Koolau exploratory tunnel project on the island of Oahu, Hawaii. The testing evaluated the performance of dowels to be used as initial ground support for two 12- by 15-meter (40- by 50-foot) tunnels within weathered basalt. The program tested four dowel types of three different lengths. Both grouted and friction dowels were tested. The program determined which dowels were more effective in carrying load and noted any special procedures that would be required during construction. This paper presents the test results and discusses how these results were used in the design.

Jan 1, 1991

By Thomas H. Wake, Timothy M. Tower

A continuing trend in raise drilling is the movement toward increased automation. This paper discusses the reasons for automating a raise drill, which include labor saving, faster and smoother operation, quicker response to blocky ground, and improved data logging and diagnostics. It gives a "wish list" of features when automating a raise drill, from simple shutdown control through unattended operation. It discusses the principles involved in closed loop control of a sluggish mining machine with large inertia, and covers functions such as data logging and remote control. Results are presented from a field test on a production raise drill.

Jan 1, 1991

By P. F. R. Altounyan, I. W. Farmer

Groundwater freezing was used to stabilise 8m thick beds of saturated and weakly cemented sands at a depth of 170m, during driving of twin 1 in 4,5.2m o.d. circular drifts from the surface to the Coal Measures through 600m of Permo-Triassic strata. Instrumentation was installed during erection of the lining in frozen and unfrozen ground to measure ground and groundwater pressures on the lining and ground temperatures up to lm into the frozen ground. Observations showed that following thawing, effective lining stresses in the frozen zone were low, indicating minimum strata disturbance during freezing and subsequent machine excavation. Groundwater pressures were lower than expected.

Jan 1, 1981

By Y. Akin, M. S. Celik, T. Batar, F. Arslan

Despite its importance in various diverse industries, research on beneficiation strategies of boron minerals has not received enough attention. Boron minerals are primarily upgraded by wet processing methods. However, severe environmental constrains have accelerated the development of dry processing techniques such as calcination. Interestingly, the boron minerals colemanite, ulexite and borax undergo decrepitation, shrinkage and expansion, respectively, upon heat treatment. Each mineral then requires a different beneficiation scheme. In this study, laboratory and pilot-plant studies conducted in our laboratories on the calcination of boron minerals are briefly reviewed and their implications to commercial operations are discussed.

Jan 1, 1999

By D. Marinakis

Gas hydrates (GH) are crystalline compounds consisting of a water molecule lattice, in the cages of which suitably sized molecules, such as methane or other light hydrocarbons, are confined. Although this solid phase looks similar to common ice, it contains substantial amounts of natural gas. The necessary conditions for natural gas hydrate formation exist in some deep-sea marine environments and in permafrost regions. Despite the extensive research, which has been conducted in the fields of exploration and exploitation of natural gas hydrate deposits over the last decades, there is still great uncertainty over the estimated amount of hydrates that these reserves bear. The present work examines some key features of sediments which affect their capacity to host gas hydrates. The hydrate content of a natural hydrate formation is correlated qualitatively with factors such as temperature, effective porosity, mineralogical composition, bio-surfactants, pore pressure and compaction pressure.

Jan 1, 2006

By W. A. Cincilla, Z. T. Bieniawski, E. Unal

Although coal mine tunnels such as the main haulageways or roadways are the lifelines of coal mines, little attention has been paid to them in terms of pre-construction planning and design. This paper presents the results of research aimed at improving design methods for coal mine tunnels. Studies of the current practice and design needs in the United States were performed for coal mine development entries. A design approach evolved for coal mine tunnels is presented. It is based on field investigations and laboratory model studies aimed at integrating into reinforcement guidelines for coal tunnels. An up-to-date bibliography on coal mine tunnels is provided.

Jan 1, 1981

By Roshan B. Bhappu, Sukhendu L. Barua

The economics of developing and operating small precious metal mines are unique and require much more scrutiny than larger mines since a limited tonnage must carry a heavy burden of capital investment as well as operating cost per unit ton to be mined and processed. Moreover, potential operators of small mines do not have the required expertise available to critically evaluate the technical and economic aspects of their projects. In this paper, the authors have attempted to provide technical and economic guidelines for developing and operating small precious metal mines. Capital and operating cost estimates as well as return on investment are provided for various scenarios utilizing different mining and processing techniques.

Jan 1, 1987

By Frederick W. DeVries, J. Brent Hiskey

Cyanide has been recognized for about a century as the most effective reagent for processing gold ores. Cyanide leaching has been adapted to various metallurgical settings and continues to be improved. However, in recent years attention has been directed to alternative lixiviants for treating refractory ores and concentrates, and to the development of less environmentally controversial substitutes for cyanide. This paper reviews some of the reagents considered as alternatives to cyanide and focuses on environmental implications for using these newer reagents.

Jan 1, 1992

By Terry Mudder

Long-term anaerobic biochemical treatment for draindown of residual solutions is a cost-effective way to close a heap-leach pad. This article presents a laboratory evaluation of anaerobic biochemical treatment of cyanide heap-leach pad solutions. The traditional approach to heap-leach pad closure is to rinse the pads with multiple pore volumes of fresh or recycled treated water. The effluent from an initial rinse is often treated and recirculated until the solutions passed through the heap meet the appropriate numeric and narrative water quality standards. Column rinsing tests are completed during project planning to determine the number of pore volumes of fresh or recycled treated water required to rinse the pad to meet long-term closure requirements. A traditional closure plan generally includes provisions to sample the rinse effluent and rinsed solids (the Meteoric Water Mobility, Procedure or USEPA 1312) to verify that chemical requirements are being met.

Jan 1, 1995

By W. M. Shaver, R. Letourneau, W. R. Dengler

Dynatec Mining Limited contracted to sink a 1500 metre (4960 ft.) concrete lined shaft for Falconbridge Nickel Mines in Sudbury, Ontario, Canada. The shaft is 6.3 metres (20.5 ft) in diameter inside the concrete lining and is equipped with steel furnishings. Dynatec used the owner supplied 4.6 metre (15 ft.) diameter double-drum hoist to sink the shaft with 12.5 tonne buckets for muck removal and 4 cubic metre concrete buckets for concrete placement. One of the unique features of the shaft sinking operation is the use of a four-boom electric hydraulic drill jumbo permanently mounted in the shaft sinking stage. This paper will describe the performance obtained with the electric hydraulic drilling equipment and the high capacity muck removal and concreting equipment.

Jan 1, 1991

By Steve Kral

Competition in the gold mining industry throughout the world has become fierce in recent years. The challenge facing operations personnel is to produce more gold for less money. Likewise, the explorationist's charge is to find more gold in a more cost-efficient manner. That means using new technology to find new gold deposits and expand present ones. More accurate mapping instruments are available to geologists in the search for new deposits. Advanced geophysical and geochemical methods enable explo¬ration teams to review previously mined districts in their search for minable reserves. Four technical sessions on the geology, exploration, and development of gold deposits were part of the program at `world Gold '89,' a Gold Forum on Technology and Practices," held by SME and The Australasian Institute of Mining and Metallurgy in Reno, NV, Nov. 5-8, 1989.

Jan 1, 1990

By M. David Monroe

Getting the best match between truck and haul road requires examining the cost effects of many factors. Most mines use a bottom line measure based on cost per ton of material moved. This measure focuses on the two components of truck haulage cost per ton: productivity (or performance) and operating cost. For specific tasks, productivity can be measured or predicted using either field measurement or modeling. Individual tasks can be combined to provide a larger scale, longer term net figure for total mine output. True cost is more difficult to capture. Factors are time- and task-oriented and can be influenced by a summation of factors over a truck's lifetime. For example, "allocated" costs, such as owning (depreciation) and some repair costs, are spread over long periods. Items such as fuel and tires can be tied more directly to certain tasks. This article focuses on the more direct, task-oriented factors that affect truck productivity and cost. Major factors The relationship of haul roads and trucks means that each must be examined separately to isolate the most important factors affecting performance and cost. There are many factors but the most important are:

Jan 1, 1992

By Daniel Hodouin, Claude Bazin, Sami Makni

A method is proposed to perform on-line data adjustment and inference of unmeasured variables, using measured flowrates and on-stream assays in mineral processing plants. The algorithm minimizes a weighted sum of squared residuals of the measured variables and squared species imbalances around the flowsheet nodes. The method is based on a trade-off between the material transient accumulation, evaluated by the imbalances, and the data inaccuracies, evaluated by the residuals (i.e. the adjustments brought to the measured values). A recursive algorithm is developed for on-line implementation of the method. It is a real-time extension of the hierarchical method for balancing steady-state data for bilinear mass conservation constraints. An illustration for a simulated flotation circuit is provided.

Jan 1, 1995

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 K. Biswas

A finite-element algorithm was developed for an axisymmetric heat-transfer problem involving phase change. The finite-element treatment of the phase-change problem was dealt with by using the enthalpy method. The finite-element algorithm was subsequently applied to model the heat exchange between mine ventilation air and frozen ground in the presence of roof bolts in an underground mine with permafrost. This paper analyzes a single bolt in the problem domain with the convection boundaries at the roof level of the mine airway. A short-term study, comprising the evaluation of roof bolting (friction-anchored type), was conducted, and recommendations were made regarding the applicability of roof bolts as a support system for a given thermal condition.

Jan 1, 1996

By Robert A. Robinson, Steven R. Thompson, Harvey W. Parker

The Mt. Baker Ridge Tunnel, under construction in Seattle, will be the world's largest-diameter soil tunnel with an inside diameter of 19.2 m (63 ft) and an effective outside diameter of about 24.4 m (80 ft). The five-lane highway tunnel will be constructed using a "stacked-drift" scheme in which an articulated or "flexible" tunnel lining consisting of 24 concrete-filled drifts is constructed to form a horizontal compression ring followed by removal of the soil core. Geotechnical factors, including variable strength hard fissured soils, high horizontal stresses, potentially unstable sands, and prior slope instabilities, significantly influenced the innovative design and construction approach.

Jan 1, 1983

By Gary S. Brierley, Ronald E. Romley, Alan L. Howard

The Price Road Drain Tunnel in Tempe, Arizona is part of the drainage system constructed in conjunction with the Outer Loop Highway in metropolitan Phoenix. The Outer Loop Project is a part of a much larger expressway system that includes other large drainage tunnels such as the Papago Freeway Drain Tunnels. Large diameter downhole inspection borings were utilized to obtain subsurface data for the design of these tunnels. Subsurface data obtained from the large diameter borings resulted in the development of empirical parameters that were successfully incorporated into the Geotechnical Design Summary Report and which satisfactorily predicted ground behavior, formed the basis for improved geotechnical design criteria, and facilitated the cost effective assessment of third party risk. The purpose of this paper is to describe the subsurface exploration program performed for this project and to explain the methods used to evaluate underground construction procedures.

Jan 1, 1991

By G. Oswald

The fatty acid flotation process has been used to produce phosphate for decades, yet the chemical mechanism involved has never been thoroughly investigated. A basic knowledge of the process is lacking, and as such, industry has had to develop their own guidelines for the design and operation of conditioning and flotation equipment. These guidelines are the result of many trial and error attempts, and are not by any means universally endorsed. There are almost as many opinions about how to operate a plant as there are practitioners of the art. This paper covers the currently recommended rules for design as viewed by one practicing phosphate metallurgist.

Jan 1, 1993

By G. M. Bernard

Cerro Colorado lies on the eastern edge of the Atacama Desert in the foothills of the Andean Cordillera of northern Chile. Compañía Minera Cerro Colorado SA (CMCC) operates Cerro Colorado. CMCC, headquartered in Santiago, Chile, is wholly owned by Rio Algom Ltd., of Toronto, Ontario. Cerro Colorado is located 120 km (75 miles)east of the port city of Iquique. Access is by 30 km (19 miles) of paved highway and 70 km (43 miles) of upgraded road. The mine site is located at an altitude of 2600 m (8531 ft) on a gentle west-sloping plateau adjacent to a deep canyon (Quebrada de Parca) to the north. Temperatures are moderate, ranging from 5° to 30° C (41° to 86° F) with an average annual rainfall of 20 mm (0.8 in.). The plateau is generally covered with 20 to 30 m (65 to 100 ft) of Quatemary sand and gravel overlaying bedrock. In the immediate vicinity of the Cerro Colorado deposit, a semicircular embayment has been eroded into a steep canyon wall that cuts through the surface gravels to expose a considerable section of the underlying bedrock.

Jan 1, 1995

By Kenneth J. Reid, Marian S. Stachowicz

A preliminary evaluation of a new in-stream particle size analyzer has been carried out using materials obtained from a taconite plant in Northern Minnesota. Results are reported for bench scale, pilot scale and full scale tests, the latter being carried out in a taconite plant concentrator. The unit employs a novel scanning laser microscopy principle and details of the equipment configuration and operating principles are presented and discussed. Data acquisition is via an eight channel digital electronic system and particle counts are collected on the basis of reflected light pulse time intervals which are a direct measure of particle size. Output is available as an eight point individual or cumulative size distribution or as computed averages. The practical aspects of sample point location and flow requirements for reproducible results are outlined and discussed.

Jan 1, 1990