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By P. E. Nielsen, T. L. Loga, B. B. Mauko

A numerical model is presented which simulates the dynamic fracturing process for a circular geometry fracture in a uniform stress medium. The dependence of crack aperture and net pressure in the crack upon various dominant parameters of the fracturing process is discussed. An analysis of a 75% nitrogen foam fracture in a coal seam at 5600 feet (1707 m) is also presented. The analysis is based upon the discussed parametric trends, the job records of treatment parameters, and a Nolte plot of net downhole pressure. It is interpreted that fracturing with water, in pre-foam fracture pump tests, resulted in significant fracture height growth. However, the subsequent foam fracture had reduced height growth due to the high effective viscosity of the foam and due to the higher magnitudes of elastic modulus and stress in the bounding rock strata with respect to the coal.

Jan 1, 1986

By E. Alaphia Wright

An accepted approach to open pit mining sequence planning is one of computer aided planning where: the planner works out his mining sequences by trial and error using interactive graphics; This approach gives results that could in- variably be improved given more time for the planning exercise. Increased emphasis on interactive planning reveals a need for simple formalized procedures for improving mining sequence planning practices. This paper discusses a case study in which Dynamic Programming (DP) is used in mining sequence planning. It is shown that DP can be applied to identify various intermediate, pit boundaries. These are then arranged in descending order of economic values and their material contents analysed with respect to tonnages, grades, production requirements, and equipment capacities. Those increments which best satisfy defined conditions are selected and the others discarded. The mining sequence is thus built up as a chain of best- economic valued mining increments satisfying given production requirements and constraints.

Jan 1, 1989

By Ahmet Tezcan, Zeki M. Dogan, Yalçin Kaytaz

Autogenous grinding in Turkey was first applied to quartzite where the mill is grate discharge type with an internal diameter of 2.99 m, having a length of 3.20 m and a capacity of as to 11.0 tons per hour. The second autogenous grinding was applied to a copper ore at Murgul Cakmakkaya Flotation plant of (KBI) Black Sea Copper Works having three mills 26 feet in diameter and 10 feet in length in close circuit with hydrocyclones. Recently, alterations were made in grinding circust by adding pebble mills. Furthermore, rubber liners and lifter bars were introduced pebble extractor and classifier were new features in the primary mills and circulating load was reduced by 20-50 tons per hour. At the end of these charges, capacity of each mill line was increased to 48 tons per hour with a full capacity of more than 9000 tons per day. Thirdly, autogenous grinding has been executed successfully on the slags of Samsun Smelting Plant of (KBI) Black Sea Copper Works with a mill of 20 feet in diameter and 6 feet on length having pebble mill following autogenous grinding.

Jan 1, 1992

By Richard Belair, John Read

Ask someone what they can tell you about the Royal Canadian Mint and most likely the first thing that they will mention, is coinage. The Royal Canadian Mint manufactures Canada's one-cent coins, nickels, dimes and quarters - over 1 billion per year. Most of these coins use copper and nickel as base material, and all of this metal is mined, refined and processed in Canada prior to being shipped to the mint for coin production. In 1985 alone, 1270 metric tons of Canadian nickel and 2160 metric tons of Canadian copper were absorbed in circulating coinage. July 1987 will have marked the introduction of Canada's new one dollar coin, an important new addition to Canada's monetary system. The first phase of this program will consume about 2,235 metric tons of Canadian nickel in the initial production run. Annual requirements in subsequent years are estimated at 225 metric tons. The Royal Canadian Mint is also a major producer of circulating coinage for foreign countries. Since the state-of-the-art Winnipeg plant swung into full production in 1976 the Mint has struck more than 5.2 billion coins for some 35 nations around the world. 1985 sales have increased almost 6 fold over 1984. 1987 already shows commitments for a further significant increase in volume in this business. The use of Canadian metals in export to foreign nations as coinage adds still more to the Royal Canadian Mint's key role as a major market maker for Canada's mining industry. The success of the Mint in this realm can be directly traced to it's 75 years as one of the world's most important refiners of gold. Today, the Royal Canadian Mint is the largest refiner of gold in the Western Hemisphere, and the third largest, by volume, in the world. The R.C.M. hallmark on kilo bars, 100 troy ounce comex bars

Jan 1, 1987

By Paul D. Kovscek, Charles D. Taylor, Edward D. Thimons

When blowing ventilation is used on a mining section, a machine-mounted scrubber is often required to maintain face dust levels below 2 mg/m3. Operation of the scrubber also affects airflow patterns at the face and the dilution of liberated methane. Reductions in scrubber flow can result in increased methane concentrations. During mining, loading of the scrubber filter with dust is likely to reduce airflow. Detecting changes in scrubber flow is difficult, especially with extended cutting, because the machine must be operated from a remote location. Tests were conducted to demonstrate how scrubber airflow could be continuously monitored at a remote location. Three variables, static pressure at the fan inlet, differential pressure across the scrubber filter, and scrubber fan motor current, were continuously monitored while the scrubber filter was incrementally loaded to reduce air flow. The results show that monitoring each variable provided a way for estimating scrubber flow.

Jan 1, 1995

By L. Xiao, P. Somasundaran

Using potassium oleate as a collector and alizarin red S as a modifying agent, selective depression of dolomite from francolite was achieved in an alkaline medium (pH > 9.0). Adsorption of alizarin reds alone on dolomite was found to be higher than that on francolite. Complimentary adsorption experiments of alizarin red S and oleate showed that oleate adsorprion was increased in the presence of alizaring red S. The results are explained in terms of comparative adsorption for the active sites on francolite and dolomite by oleate and alizarin red S and their interactions with dissolved mineral species in solution.

Jan 1, 1990

By Dale A. Bivens

INTRODUCTION The Waste Isolation Pilot Plant (WIPP) is currently being constructed for the United States Department of Energy in SE New Mexico. The purpose of the project is to store low level transuranic waste in an underground environment which will ensure a safe atmosphere for the life of the stored waste. Ohbayashi was contracted by the DOE to sink two shafts and underground drift development which will be used to conduct a series of long term experiments in order to finalize the suitability of the geology and the environment for the transuranic waste storage. The two shafts sunk at the WIPP site were excavated around a borehole by conventional methods. The excavation around a borehole eliminates some of the established blind bottom sinking techniques, but creates unusual problems which must be pre-planned and scrutinized closely. An analysis of the slashing to the borehole technique will be given. WASTE SHAFT The waste shaft (w/s) is 5.8 meters (19 feet) in diameter and will be used primarily to transport the radioactive waste to the underground storage area. A pre-existing 1.83 meter (6 feet) diam borehole was taken to a depth of 655 meters (2150 feet) to the existing drift; at this level, a 38 meter (125 feet) sump was installed using blind bottom sinking techniques. Geology The primary geology for the w/s excavation is redbeds, anhydrites, dolomite, mudstone and

Jan 1, 1985

By Timothy N. Dunne, Joseph M. Gonzalez

This paper presents the case history of a comprehensive geotechnical investigation for the Crosstown Transport Facility, a 10,880 m long, 3.2 m diameter pressure tunnel proposed for construction in San Francisco, California. The proposed tunnel would be part of the City and County of San Francisco's Clean Water Program, and its purpose would be to convey stormwater and sewage from the east side of the City to the Pacific Ocean. Tunneling conditions were defined by surface geologic mapping, 94 exploratory borings, surface and borehole geophysics, aquifer testing, Goodman Jack testing, pressuremeter testing, and laboratory testing. Through the use of advanced coring techniques and a strictly controlled drilling fluid system, core recovery averaged 90 percent in the sheared and fractured rock of the Franciscan Formation. As a result, over 1,400 linear meters of rock core was recovered and is available for examination.

Jan 1, 1983

By Kostas Fytas

Canada still remains today a strong resource nation with a huge geological potential. Canada ranks among the top five leading countries in the production of 15 major minerals. Acid mine drainage (AMD) is a serious environmental problem that preoccupies the Canadian Mining Industry. Considerable amounts of money are spent every year in an effort to prevent or reduce the acid mine drainage production. It is estimated that across Canada there are a few thousand abandoned mine sites as a result of the last fifty years of mining. Most of these sites are acid producing presenting a serious threat to the environment. It has been estimated that the cost of stabilizing and reclaiming these sites across Canada will be over $5 billion over the next twenty years. Current practices for decommissioning acid producing sites are water covers (flooding), dry covers, revegetation and treatment of the acid effluents. This paper presents the technical and legal issues of mine closure and reclamation in Canada. The methods used in the revegetation of acid producing mine sites is also presented This paper also reviews the financial guarantee requirements for mine closure by the provincial legislations in Canada. A case study of stabilizing and reclaiming a sulphide tailings area in the Sudbury region is presented. It illustrates the challenges facing the Canadian Government and the mining companies in restoring and revegetating the closed and abandoned mine sites across Canada.

Jan 1, 2002

By Graham A. Mathieson

A detailed breakdown of capital and operating costs is an essential element in the planning and evaluation of any mining project. The OPCOST System was developed by Golder Associates to provide mining engineers with the facility to synthesize detailed cost estimates for all aspects of an operating or potential open pit mine. The system can also be applied to underground mines equally as well. Such estimates can be prepared at a variety of levels depending on the detail required by the project. The OPCOST System is a suite of computer programs linked through a common hierarchical data base. It simulates the thought and reasoning processes within the quantity takeoff and cost estimation phases of a mining project. The system was developed as a mining cost engineering tool on the basis that it would have to satisfy a variety of purposes, namely:

Jan 1, 1982

By David T. Swanson

The term "pressure tunnel" in the broad sense includes all hollow spaces, aligned along an axis and surrounded by rock, which are suitable for pressurization. In particular, this category includes: • horizontal or slightly inclined water pressure tunnels; • vertical or inclined pressure shafts; • pressure chambers or shafts of surge chambers; and, • compressed air storage tunnels. The main problems in the design and construction of pressure tunnels result less from their length or size than from the requirement for watertightness and, dependent upon this, reliability in operation and economy in construction. Where the lack of sufficient overburden does not permit the rock to accept the internal pressure in the tunnel, or where this pressure is so high that the watertightness is in doubt although the stability of the tunnel shell is not in question, a pressure tunnel must nevertheless be reinforced. Surge chambers, pressure tunnels and tailraces which are subjected to relatively low internal pressure, usually not much in excess of 1.5 MN/m2, are eminently suitable for construction in post-tensioned concrete. Pressure shafts, which as a consequence of the high water head are subject to a considerable maximum service pressure, are usually lined with a steel tube, a considerable proportion of the internal pressure being transmitted to the rock by backing concrete. TYPES OF LINING FOR PRESSURE TUNNELS In general, the type of lining will depend upon the nature of the rock. As a result, pressure tunnels usually are not uniform in con-

Jan 1, 1981

By K. Avarmaa, P. Taskinen

"The solubilities of rhodium (Rh) in a molten silver alloy in doré-smelting conditions for treating copper refinery slime at temperatures of 1,000 to 1,300 °C were measured using a high-temperature equilibration-quenching technique and direct phase analysis by electron probe X-ray microanalysis. The results obtained indicate that the solubility of rhodium in molten silver is very limited: only 0.04 to 0.26 weight percent at 1,000 and 1,300 °C, respectively. The thermodynamic properties of rhodium in molten silver were estimated from the solubility data. The compositions of the solid rhodium alloys in equilibrium with molten silver-rich doré metal were also measured in this study. The excess rhodium in the doré alloy will precipitate during the refining as solid, greater than 99 weight percent Rh.IntroductionSilver refining is a core step of the processes of anode slime treatment and precious metals recovery in copper refineries (Hait, Jana and Sanyal, 2009; Ludvigsson and Larsson, 2003). It separates the oxidic materials, such as nickel oxide (NiO) and barium sulfate (BaSO4), from metallics after the de-coppering and de-selenation steps of the anode slime, and refines the silver bullion from the undesired elements present (Cooper, 1990; Hyvärinen, Lindroos and Yllö, 1989). Doré metal is a silver-rich alloy which after the smelting step will be refined electrolytically, and the remaining constituents of gold as well as the platinum group metals (PGM) will be subsequently recovered in their own processing stages.Because of low concentrations of PGMs in copper, they are typically soluble in the doré metal in anode slime treatment. This can be concluded from their binary phase diagram data with silver (Massalski et al., 2007). One exception is sometimes encountered in the anode slime smelting operations if the smelter feedstock is rich in rhodium, as may be the case if the raw materials contain secondary raw materials such as e-scrap. The solubility of rhodium in solid silver is less than 0.04 weight percent (Królas and Sternik, 1995), and its solubility in molten silver is highly uncertain. The only experimental information in the literature (Królas et al., 1993; Elliott, 1985) suggests that the silver-rhodium alloy system at 960 °C forms a eutectic, which locates less than 2 °C below the melting point of pure silver (Arblaster, 2015). Early observations (Rössler, 1900) propose that rhodium is insoluble in molten silver even if solid silver-rhodium solutions have been recently produced on a nanoscale (Kusada et al., 2010).The aim of this study is to measure experimentally the solubility of rhodium in molten silver at doré metal smelting and refining temperatures. The silver alloy used to mimic the doré alloy contained silver and about 1 weight percent of the alloying elements copper, gold, palladium, rhodium and tellurium. The experiments were carried out in metal-slag equilibria with nitrogen-oxygen mixtures as the atmosphere, employing an equilibration-quenching technique and using direct phase composition analysis by electron probe X-ray microanalysis (EPMA) (Jak, Hayes and Lee, 1995)."

Jan 1, 2017

By C. J. Pritchard, R. D. Jacksha, K. V. Raj, C. B. Sunderman

In underground metal/nonmetal mines, repeated localized short-term exposure to high levels of airborne contaminants can become a serious health issue. Currently, there are no common mechanisms to control or mitigate these short-term high exposures to contaminants. To improve miners’ health and safety, the U.S. National Institute for Occupational Safety and Health’s Spokane Mining Research Division (SMRD) is developing a smart monitoring and control (SMAC) system for the real-time monitoring of mine air quality, with integrated countermeasures to reduce high concentrations of airborne contaminants in localized sections of mines. To develop and test a SMAC system capable of being implemented in an underground mine, SMRD researchers built a test apparatus incorporating a fan, louver, ducting and sensors combined with atmospheric monitoring and control software. This system will institute effective countermeasures to reduce contaminant levels, improving miner safety and health.

Jan 1, 2018

By C. P. Lazzara, R. W. Pro, A. C. Smith

The U.S. Bureau of Mines conducted a study to evaluate the effectiveness of automatic water sprinkler systems in the extinguishment of incipient conveyor belt fires under ventilated conditions. Large-scale experiments were conducted using a double strand conveyor belt configuration. Standard response, pendent-type sprinklers, with activation temperatures of 100°C, were installed above and between the two strands of belting, in accordance with Federal standards for sprinkler system installations in belt drive areas. Experiments at airflows of 1.1 and 4.6 m/s showed that the sprinklers activated later, the peak heat release rate was larger, and more betting was consumed at the higher airflow. In experiments with 74°C, fast response, directional sprinklers, the sprinklers activated at the same heat release rate for both high and low airflows, but the peak heat release rate and amount of bett consumed was slightly higher at the lower airflow. Experiments were also conducted with 100 °C, standard pendent sprinklers installed above the top belt, in accordance with the National Fire Protection Association (NFPA) Standard 123 for sprinkler system installations in conveyor belt drive areas in underground coal mines. In these experiments, the heat release rate and amount of betting consumed was larger at the higher airflow.

Jan 1, 1995

By C. L. Karr

Researchers at the U. S. Bureau of Mines have developed a technique for producing adaptive control systems using fuzzy logic and genetic algorithms. These controllers can be used to efficiently manipulate complex systems in real-time. Furthermore, they can achieve an acceptable level of control despite limited feedback in the problem environment. The control systems that result from the implementation of the Bureau-developed technique are able to recognize when changes have occurred in the problem environment, evaluate the magnitude of these changes, and alter the strategy being used to control the problem environment. Fuzzy logic is used to provide the controller with a rule-base that mimics the "rule-of-thumb" approach generally adopted by humans in the area of process control. Genetic algorithms are used to provide the controller with the adaptive capabilities necessary for the control of complex time-varying processes popular in the minerals processing industry. The effectiveness of this technique is demonstrated on a laboratory pH titration system. The pH system includes a changing setpoint, titrants with varying concentrations, and the possible addition of a buffering solution.

Jan 1, 1993

By S. P. Brown, J. E. Worthington

Increasingly, exploration geology seems to be growing into a practice overly separated from production geology, yet the eventual purpose of exploration is a producing mine. To help in the search for new deposits, exploration "lessons" will be drawn from the papers given at the Fall AIME Applied Geology Symposium. In addition, examples will be re-emphasized to show how early observation of matters now routine to mine work (for example, hydrology, rock mechanics, oxidation state) can help increase the effectiveness of exploration.

Jan 1, 1992

By L. MacHue

Sulfur containing collectors have been shown over the years to function as strong, selective and non-selective sulfide mineral collectors. Unfortunately, the majority of the widely known sulfur based collectors are of low molecular weight, volatile and subsequently, possess an objectionable odor. Higher molecular weight sulfur based collectors (C9 and higher) are significantly less odiferous due to lower volatility and lower vapor pressures. In this study, a specific proprietary higher carbon number collector, Orfom® MC 37, was blended and used successfully to recover 2-3% additional molybdenum in a laboratory flotation system, when compared to a standard collector blend. Copper recoveries were also positively affected. Further testing is required to give additional conditions favorable to increased copper and molybdenum recoveries, but indications at this time show the proprietary sulfur based collector blend to be a selective collector of molybdenum, while providing a significant increase in copper recoveries.

Jan 1, 2010

By Herbert E. Allen, Andrew F. Kingery, Spyros P. Pavlou

This paper examines and compares the role that chemical speciation plays in the environmental aquatic toxicity of two metals - copper and arsenic. Copper is shown to have well-understood chemical speciation equilibria, but poorly known species toxicities. Arsenic presents the opposite case, with unpredictable speciation in aquatic systems, but is relatively easy to evaluate toxicologically. Speciation is not currently incorporated into Water Quality Standards. This can have a major impact on the cost of environmental containment and cleanup.

Jan 1, 1992

By S. S. Nadgauda, A. J. Hathaway

Typically, as long as the coal quality is within the specified range, electric utilities have used delivered cost of fuel per million Btu as the primary criteria for qualified coals when making coal-procurement decisions. Such an approach may not fully address the total cost of using different quality coals at a given plant. A practical and easy-to-build model is described for estimating plant-specific utilization costs for coals of different qualities. Examples are included to illustrate the modeling results for plants operated by two utilities. While the model has certain limitations, it does represent an improved method for evaluating coal bids, and, consequently, reducing generation costs.

Jan 1, 1990

By Ugo Preti, Gianfranco Ferrara, Mark C. Williams, Thomas P. Meloy

Theoretical and experimental lockedness profile curves are the same when the model assumptions are met. They appear different because of the way the data is presented. Continuous theoretical lockedness profile curves present all the data, including the wings of the curves giving them the deep U-shaped configuration. Experimental lockedness profile curves, because of the measurement methods, are discretized, obscuring the wings. If the continuous theoretical curves are discretized, they are similar to the experimental curves. When a float sink test is used to measure an interval of locked particles, the integrated averaging of the separation process obscures the wings of the continuous theoretical curve. To disclose the wings with experimental data, narrow density or measurement intervals must be used.

Jan 1, 1992