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By Thomas J. DeMull

Amax Gold's Sleeper Mine was brought to production as an open pit mining, cyanidation milling operation in March 1986. The Sleeper deposit is unique in that it contains zones of very high grade gold ore. Despite blending of ore, mill head grades have varied over a broad range. These grade variations were anticipated during mill design and affected, in particular, the sizing and selection of equipment for the CIP circuit. When grades proved to be even higher than anticipated, design operating parameters were adjusted shortly after start-up to accommodate the higher grades. Operating results have been excellent: during the first 18 months of operations the Sleeper mill has processed 375,600 tons of ore and produced 229,000 ounces of gold.

Jan 1, 1998

By H. Yoon

Several processes involving injection of sorbent and humidification water downstream of the air preheater in a coal-fired boiler unit, are being developed as low capital cost retrofit S02 control options. Extensive laboratory work, pilot plant programs and larger scale programs have developed performance data and design information. Many of these programs were supported by the U. S. Department of Energy (DOE) as "proofs-of-concept" of three different processes proposed by Dravo, Bechtel and General Electric. Based on these project results, DOE formulated a comprehensive in-duct sorbent injection development program to fully commercialize the technology by 1992. Also, EPRI will conduct a 4 MWe pilot program to develop its HYPAS process. The Consol Coolside process is scheduled for utility demonstration in 1989 on a 104 MWe unit at the Ohio Edison Edgewater Station under partial sponsorship of the DOE Clean Coal Technology Program.

Jan 1, 1989

By Harold G. Arthur

INTRODUCTION Stillwater Tunnel construction is scheduled to start in the spring of 1973. The tunnel will be the site of an extensive program in rapid excavation research. This paper presents a progress report regarding our plans and relates the tentative decisions which have been made on how to carry out the research effort. The details are subject to revision as more input is obtained from other Government agencies interested in tunnel construction and from experts in industry and educational institutions. The objective of the research program is to bring about faster, less costly tunnel construction. This objective will be pursued through the development, improvement, and evaluation of various construction systems and investigative techniques. The need for this kind of program was recognized by the National Research Council, in its authoritative report "Rapid Excavation - Significance, Needs, Opportunities." (1) The Council advocated a federally funded $200 million, 10-year program to help meet the $69 billion market it expects in underground excavation between 1970 and 1990. The significance of tunnel construction to Reclamation is made clear by statistics of its tunneling experience and outlook. Reclamation has constructed 174 water conveyance tunnels totaling over 190 miles, Six tunnels are presently under construction which have a combined length of about 27 miles. There are on the books nine authorized, but unfunded tunnel projects totaling another 70 miles in length. Many more miles of tunnels are included in programs in various stages of investigation.

Jan 1, 1997

By O. M. G. Newman

The Electrolytic Zinc Company of Australasia Ltd., generates a jarosite waste at its Risdon smelter. Since 1974 this waste has been disposed of at sea off south-east Tasmania. As part of a monitoring programme prescribed by the Australian Government, bottom sediments from the disposal zone are monitored regularly. QEM*SEM image analysis complements conventional chemical analysis, having the ability to partition the occurrence of an element between sediment particles of metallurgical and natural origin. The adaptation of QEM*SEM techniques to the evaluation of bottom sediments provides insight into the fate of the particles of jarosite waste.

Jan 1, 1989

By K. E. Brown, T. D. Murphy

At Monterey Coal's No. 1 Mine in central Illinois, it became necessary to predict if the sulfur content of individual trainloads of coal would exceed a contract sulfur maximum. Using geostatistics and Monte Carlo-type simulations, a forecasting procedure was developed to meet this need. The developed procedure predicts the monthly, mean sulfur content of the coal shipped and the probability of individual shipments exceeding the contract limit. During the first five months of using this procedure, the forecasted, monthly mean sulfur value was within 0.03% of actual. This represents a significant improvement over the inverse-distance, gridding-based, forecasting used previously.

Jan 1, 1994

By W. M. Kidd

INTRODUCTION Uranium mine inspection in Canada forms one element of the enforcement of the Atomic Energy Control Act; it is under this Act that all Canadian uranium mines and mills are licensed to operate. Inspection duties are carried out by a small core staff of federal government inspectors (working for the Atomic Energy Control Board (AECB)) largely supplemented by provincial mine inspectors working on behalf of the AECB. Unlike most resource extraction in Canada, uranium mining is under federal jurisdiction and consequently it was the AECB who decided in 1975 that changes in the Canadian uranium mining industry, particularly its expansion and the expanding role of the mine inspector in the limiting of exposures, warranted the offering of a special radiation protection training course. The Uranium Mine Inspector Training Course (UMITC) was first conducted in 1976 at the Elliot Lake Centre in Elliot Lake, Ontario. Subscription for the course was not limited to mine inspectors to enable union stewards, management personnel and provincial/federal labour inspectors to attend. This paper will present an outline of the course content, the format of its presentation and non-curriculum aspects of running a course of this type in uranium-producing community. The core lecturers for UMITC are drawn from the Radiation Protection and Uranium Mine Divisions of the AECB. In addition, guest lecturers are invited from universities and medical research centres together with industry professionals and government researchers. In all some twenty-four plus presentations are made over the first five days of lectures. The program topic areas, hazards, controls, measurements, record-keeping and health effects are preceded by an intensive half-day session on radiation fundamentals. TOPICS Hazards [Dust] A review of the dynamics of airborne particles including the effects of particle size, gravity and wake-turbulence on the behaviour of dust clouds. Associated topics are migrational aspects of dust particles and specific dust-generating mine operations. [Radiation] Canadian uranium mines are increasingly diverse in nature ranging from large scale low-grade underground operations in Elliot Lake to smaller high-grade open pits in Saskatchewan. Papers are presented on assessments of internal and external exposure, the metabolic pathways of ingested or inhaled radiation and the specifics of mine and mill hazards. Radiation hazards are further broken down into gamma surveys of uranium mines, radon daughter concentrations and problem areas. Controls The relationship between mining methods and the operating environment is critically important to ensuring safe working conditions. This refers to both the selection of machinery/devices, etc., and to engineering controls which are instituted to remedy problems created by new technology. UMITC examines a number of possible mining techniques, their criteria for selection and impact on the working environment. Control measures, ventilation practices and design, the need for continuous water misting and special open-pit precautions are presented. These lectures frequently conclude with suggestions for better operating guidelines for mine ventilation systems and the need for greater co-operation between the ventilation department and the underground crews. Measurements Uranium mining regulations stress the need for a high standard of exposure monitoring, statistical planning and record-keeping. [Statistics] Although many course participants are well versed in statistics, certain fundamentals are repeated and include, the concepts of mean, variance, standard deviation and standard deviation of the mean. Confidence levels, decision-making based on sample statistics and statistical records are also discussed. [Dust Measurement] Dust measurement is particularly critical in the mines where the high silica content of the ore body, such as those at Elliot Lake, results in the continuous generation of dust. Sampling practices, filtration, impaction, thermal impaction and electrostatic precipitation are explained together with the methods of counting samples to determine free silica. Konimetric and gravimetric techniques for dust sampling are compared and contrasted. [Radiation Measurements] Both collective and personal dosimetry systems are used in the Canadian uranium mining industry and lectures are presented on each. Techniques and possible sources of error are discussed for a variety of radon and radon daughter measurement methods - Lucas method, Tsivoglou and modified Tsivoglou, Kusnetz, Rolle. Instant working level meters and personal alpha dosimeters are explained in terms of calibration, maintenance, readout and estimation of accuracy. A lecture outlining dose estimation by means of bio-assay, whole-body counting and the use of TLD's concludes the topic. Record-Keeping An overview of the problems of changing limits,

Jan 1, 1981

By Jacques L. Mauboussin

The EUROPEAN ORGANIZATION for NUCLEAR RESEARCH (CERN) has undertaken the construction of a LARGE ELECTRON POSITRON COLLIDER (LEP), near GENEVA (Switzerland). The facility includes the main 27 km long tunnelled ring, 18 shafts, 20 experimental caverns and many auxiliary galleries. Roughly 800 000 cu.m were excavated in the molasse at 50-140 m depths, using roadheaders for caverns and auxiliary tunnels and 3 WIRTH, 4.5 m diameter, fullface TBMs for the main circular tunnel. Each TBM performs 25-30 m/day. Provisory lining behind them uses either precast concrete elements or shotcrete. Works a e being carried out by a joint-venture of European contractors led by FOUGEROLLE (France).

Jan 1, 1987

By R. D. Hendry, R. A. Pearce, Allyn J. Steward, Dennis C. Martin

This paper outlines the geotechnical exploration and design approach utilized for the Km 80 and Km 86 Tunnels on the British Columbia Railway Tumbler Ridge Branchline. Information from surface mapping, trenching and diamond drilling was used to prepare a rational support design using accepted rock mass classification systems. Four possible support types were developed and used as a basis for preparing a cost estimate and contract documents for the tunnels. A unit price contract was selected to provide flexibility and to enable rational selection of support based on actual ground conditions encountered during excavation. Although ground conditions along the tunnels are variable, the general geology and quantities of support installed were consistent with those estimated from the geotechnical investigation and design.

Jan 1, 1985

ITEC Environmental Colorado has begun reprocessing the tailings from old mining sites near Boulder, CO. And if the technology behind ITEC's pilot project at Gold Hill proves successful and profitable, the company plans to launch similar reprocessing operations in other parts of the state. The pilot project is under the watchful eye of state and federal authorities. They hope the technology becomes the answer to cleaning up old mining sites throughout the West. Remining and environmental cleanup on an economic basis, then, are ITEC's hopes in one the most environmentally conscious counties in the state. Clean up the mine dump sites and recycle the land, for a profit. In June 1998, ITEC Mineral Inc., ITEC Environmental Colorado's Canadian parent, acquired the Gold [ ] Hill Mill facility in Boulder County. Included in the acquisition was 4.4 hm2 (11 acres) containing the Gold Hill Mill and 283 hm2 (700 acres) of additional properties adjacent to the facility. ITEC estimates that there are about 910 kt (1 million st) of dump rock in the area. That is enough to make the operation viable. ITEC will sell the metals recovered through its reprocessing operations. However, due to low metals prices, ITEC is not expecting to make much money on the recovery of precious and base metals. Instead, the company plans to resell the reclaimed land for residential and commercial development or open space. The Gold Hill Mill site is the first of 17 sites in Colorado that ITEC Mineral hopes to clean up and recycle the land. Most notable among the sites is the historic Central City/Black Hawk mining district, which ITEC believes holds considerable potential. The Gold Hill Mill is located 14 km (9 miles) west of the city of Boulder and less than a half mile from the small town of Gold Hill. The mill was. last operated in 1992. The operation was forced to close that year due to environmental and cash flow problems. Gold Hill is in the middle of a region with more than 32 Mt (35 million st) of mine tailings. Independent geologists have' established the average grade of the Gold Hill mine tailings to be 4.5 to 5.3 g/t (0.13 to 0.155 oz/st) of gold and 28 to 44 g/t (0.83 to 1.29 oz/st) of silver. According to these studies, the Gold Hill mine tailings are five times richer in precious metals than the tailings of the Norebec Manitou property in Canada that ITEC is also remining, reclaiming and restoring. Upon acquiring the mill, ITEC undertook a refurbishing program that included adding a second ball mill. This increased the Gold Hill Mill's capacity to 180 t/d (200 stpd). The operation employs 15 people. "The Gold Hill Mill site will demonstrate the efficiency of our integrated remining, reclaiming and restoration process," said Maxine Stewart, president of Denver, CO -based ITEC Environmental. "The abundance of similar mine sites in Colorado presents a number of opportunities to bring the benefits of the ITEC system to other communities around the state." Holly Huyck is technical advisor to the Clear Creek Watershed Advisory Group. She said: "ITEC is cleaning up an orphan mine site that otherwise would continue to contaminate the Boulder Creek watershed with acid and excess metals. This is a win-win situation: ITEC gains marketable minerals while it reclaims mined land and helps to improve the watershed."

Jan 1, 1998

Eldorado Resources Ltd.(ERL) uses a solvent extraction process for the processing of uranium ores. The solvent extraction plant consists of 4 extraction and 5 stripping stages with regeneration carried out as required (Wyper, 1982). Extraction is carried out with a solvent consisting of 4.5 vol % Alamine 336, 4.5 vol % Isodecanol and 91 vol % kerosene. The extraction step can be represented as In equation (1).

Jan 1, 1988

By D. C. White

The Vulture Mine near Wickenburg, Arizona was a major gold producer from 1863 to 1942, having yielded about 11,000 kg Au and 8,000 kg Ag. Gold occurs as coarse native metal and electrum in quartz veins and also finely disseminated within a quartz monzonite sill and its silicified wall rock. The sill is semi-conformable within a Proterozoic volcaniclastic-dominated sequence all dipping north about 35°. Early mining focused on the vein-hosted gold particularly in the immediate hanging wall and footwall of the sill. Later efforts included some open-pitting of the outcropping sill and adjacent altered and mineralized rock. Two sets of post-mineral faults have complicated the orebody geometry.

Jan 1, 1988

By S. R. S. Sastri, G. V. Rao

Because the nickel contained in lateritic nickel ores does not occur in an identifiable mineral, it is generally accepted that these ores are not amenable to beneficiation. For this reason, such ores are either directly smelted or leached to extract the nickel. In this paper, a process for enriching the nickel content of the lateritic nickel-bearing chromite overburden, normally a waste material generated during chromite mining, is described. In this flotation process, a nickel preconcentrate containing >1.1% Ni was obtained from material containing as little as 0.36% nickel. An empirical relationship was developed to predict the grade of nickel that can be obtained.

Jan 1, 1997

By D. R. East

The concept of sub-aerial tailings deposit.ion using a managed rotational deposition system to form a deposit of partly-saturated tails for North American conditions was introduced by Knight and described by Knight and Haile (1983). The application of the sub-aerial technique, together with continuous removal of all surface waters and underdrainage outflows from the Key Lake uranium mine I s tailing storage facility in Northern Saskatchewan, Canada, has been documented by Knight and Haile (1984). Since then, the concept is being applied in the United States to tailings facilities in California, Nevada, Arizona, Utah, Colorado, Idaho and South Dakota.

Jan 1, 1989

By Gerard P. Hand

The use of graphite in industrial applications is one of the oldest in the world. Yet, it is one of the fastest-changing technologies today. Graphite was first used centuries ago in developing writing instruments and as a raw material in crucibles used in melting metal. Today, graphite is used in some of our most demanding industries. These include aerospace, electronics and automotive applications. Graphite usage has historically been split between the natural and synthetic forms. Figure 1 shows the breakdown of natural graphites and synthetic graphites used. The usage of natural graphites and synthetic graphites is split fairly evenly, although the applications are quite different. Figure 2 shows the breakdown of applications using natural graphite. The largest application is the refractory industry. This includes refractory brick and plastics, crucibles, shrouds and other refractory parts. This main application uses roughly 50% of all natural graphite. The refractory industry is an important application for natural graphite. However, the refractory markets have been struggling for several years. As demonstrated in Fig. 3 (Semler, 1996), the production of refractories in tons per year has declined by more than 32% during the last 25 years. Refractory prices have actually risen on a dollar per ton basis during that same period as the product mix has shifted to the value-added side. Raw material and production cost increases, inflation and other related costs have kept profitability at low levels for the industry. Furnace linings that once lasted 1,000-2,000 heats now last 8,000-12,000 heats. This means that tonnage requirements have gone down and quality requirements have gone up for graphite suppliers. Therefore, new opportunities and applications must be developed if the graphite industry is to grow. Synthetics are the other major forms of graphite. There are two forms of synthetic material currently used. One is the traditional type. It is made from the turnings of graphite electrode production. The second was developed in the mid-1970s in response to a shortage of conventional synthetic graphite. This occurred by a breakthrough in thermal technology. This new technology purifies, desulfurizes and graphitizes petroleum coke on a continuous basis at temperatures of more than 2,500° C (4,532° F). This product is called desulfurized petroleum coke (Desulco). It now accounts for about half of the synthetic type material used in the United States. Figure 4 shows the breakdown in the use of synthetic types of material by application. The largest requirement is for use as a carbon addition in iron and steel. This is followed by alkaline batteries and friction materials. Current technological opportunities New opportunities for graphite products are now being developed. These new areas are made possible due to the advances in graphite thermal technology. The ability to purify and modify graphite and carbon products is the key to future growth in the graphite industry. New, higher-purity, more consistent graphite products are leading to enhanced performance in current applications. They are also opening the door to new applications.

Jan 1, 1997

By G. B. Johnston

I was very interested in Professor Park's data on subsidence over longwall panels. His paragraph labeled "Conclusion," however, does not seem appropriate for the article. Nothing in the article gives any discussion of how knowledge of subsidence characteristics can be used in mine design to minimize damage. That thought may have been a reason for undertaking this study, but not a conclusion of it. From his article, I would conclude that subsidence movements last considerably longer at great depth. And the National Coal Board's subsidence prediction model represents this area reasonably accurately, though most literature claims their model predicts far greater disturbances than actually occur in most areas of the United States. Also, I would like to know, is the method used to determine angle of draw? The criterion used can make a significant difference in the value obtained. With 30 m (100 ft) spacing and a 122-m (400-ft) depth the angle between stations can be up to 14°.

Jan 1, 1990

By N. Edmonson

Frasch sulfur production/pricing decisions are based on market demand, less nondiscretionary sulfur supply. Price covers the cost of Frasch production and byproduct sellers accept the Frasch price structure. Large stocks have led Canadian byproduct producers to price aggressively at times, but their near-term drawdown suggests more passive price policies in the 1990s. Expanding continental nondiscretionary supply is combining with sizable Frasch supply increments to weaken prices. Simulations using a market model embodying these structural characteristics indicate that expanding demand may not result in substantial recovery from 1992 price lows before 1996.

Jan 1, 1995

By W. A. Niepelt, F. A. Locher

Flow in steep cascades may lead to the occurrence of a nearly periodic train of waves known as slug flow. This, in turn, may result in overtopping of the channel walls and problems with energy dissipation in receiving sumps. Experimental data from an operating facility was used to extend clear water technology for predicting the occurrence of slug flow to conditions with slurry flows. A design methodology and a design chart to determine the region of steady flows is presented that will permit the design engineer to avoid slug flow in cascade systems for conveyance of slurries.

Jan 1, 1990

By M. E. Kuchta

Research is currently being conducted at the Colorado School of Mines in the use of high-pressure water for scaling down loose rocks in underground mine openings. In addition to improved miner safety, the adhesion strength of shotcrete applied to rock surfaces treated with high-pressure water is also increased significantly, resulting in improved overall support capabilities of the shotcrete layer. Test results show an increase in adhesion strength by a factor of four on a concrete test wall cleaned with water at 21 MPa (3,000 psi) as compared to a surface cleaned at 0.7 MPa (100 psi).

Jan 1, 2003

By Eric Forssberg, Mats Hallin

INTRODUCTION Evaluation and optimization of mineral processes has been going on since the the first plant started hundreds of years ago. A huge mass of knowledge has been collected since then. The main problem with this type of empirical knowledge of complex processes is that it is very difficult to formulate and document. The methods used for collecting the knowledge is not consistent but-varies with "he person" that does it. In the late 60's and early 70's efforts were made to use computer based techniques to evaluate process performance and to formulate process models for mineral processes. Models were developed, such as the flotation model by R. P. King (1973) which is still used to simulate flotation circuit behaviour. During the 70's. a number of mass balancing packages were developed together with process simulation packages. The industrial sector also made great efforts to develop and utilize computer based systems for process control and evaluation. The expert system that BOLIDEN created in 1974 at the Kristineberg plant was a remarkable achievement considering the hardware (CDC 3600) and the software tools (FORTRAN) available at that time. The main obstacle to successfully implement optimizing computer control of mineral processes was and still is the limited knowledge about the dynamics of complex processes. There are, however. many activities going on in this area today and it seems that the technology is very near a break through. Process evaluation is the most important tool to improve and maintain the optimal performance of a process. Today dedicated computer based techniques are used for fast and reliable screening of the processes. The stages in process evaluation consist of three basic steps: - Data acquisition, manually or by data logging. - Data refining, mass balancing and parameter calculation. - Data evaluation. The refined data can then be used for model construction/calibration and subsequently for process simulation. This paper describes two studies where the techniques mentioned above are used to evaluate and simulate

Jan 1, 1991

By Leif A. Nordell, Philip E. Freeland

A paper discussing specification, methods, situations and results encountered in underground phase construction of the Rocky Mountain Pumped Storage Project near Rome, Georgia. The scope of work included excavation, rockbolt/shotcrete/wire mesh primary support and cast-in-place concrete lining of the (1) 216 m, top flared shaft, connecting 1.57 radian elbow, and 590 m tunnel to a 10.67 m finished diameter; (2) complex double bifurcation section; (3) excavation, support, installation and backfill concrete for three parallel, 135 m steel penstocks of 5.79 m finished diameter; (4) construction of a 43 m diameter reinforced concrete intake/discharge structure atop the shaft.

Jan 1, 1985