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By Adrian Brown

Over the last decade, a number of large slopes have been excavated in rock which contains families of joints or faults which dip steeply into the cut slope. Despite the absence of "adverse" structures, these slopes have exhibited alarming movement rates at very modest heights (as little as 100 meters) and slope angles (as little as 20º). Classical stability analysis suggests that such slopes should be unconditionally stable. This paper describes the toppling mechanism which has been found to be the cause of the observed movements and develops a general method for analysis of it. Simple cases are analyzed in order to provide charts which allow quick evaluation of the likelihood of this phenomenon occurring. The safety implications of such movements in slopes are also examined.

Jan 1, 1982

By S. J. Im

Bupyung Silver Mines daily treats average 14 tons of concentrates containing 9,000 g Ag per ton. Bupyung Silver Refinery uses Merrill Crowe process to recover the silver from the leach solution containing 1.0 g/l Ag; Series of experiments were carried out to recover the silver from the solution by means of direct electrowinning in place of Merrill Crowe process. The recovery of the silver was 99% when the cell voltage and the retention time were 1.9 v and 3.0 hours, respectively. Power consumption was 3.2 Kwh/kg of Ag. It was found that impurity buildup was not significant during the recycling. The direct operating cost for the electrowinning was evaluated to be $ 0.35/kg of Ag.

Jan 1, 1984

By B. Yarar

Samples of coal from an adit in the Fording River District of British Columbia showed hydrophilic properties between depths of 0-24.5 m (0-80 ft) and was naturally hydrophobic at greater depths. Laboratory experiments indicated that weathered samples (i.e., those mined at 0-24.5 m) could be upgraded by froth flotation at pH32 following slimes removal. The i.e.p. of samples varied regularly between pH = 1.6-4.1, the weathered fractions being at the lower end of the pH scale. These values followed a pattern comparable with the flotation behavior of samples. A patchwise structure for coal surfaces determining the resultant disjoining pressure which in turn determines flotation-non-flotation relationships is postulated.

Jan 1, 1983

By William C. Peters

The experiences of exploration crews with mineral land acquisition could be graphed to show a correlation with the natural law that everything tends to become more so. A single step, such as that of taking a series of deep soil samples, is sometimes delayed until some sense can be made from floating unpatented claims which are obscure in orientation as well as position-placer claims, overlapping lode claims, location posts with empty Prince Albert cans and claims with no apparent assessment work for ten years. Add to this some patented claims without monuments, a state or federal withdrawal area which may or may not invalidate preexisting claims, a loosely defined tunnel site, and some ranchers who understandably resent the separation of surface rights from mineral rights.

Jan 1, 1970

By Alexandre Mussard

How do you make a mine out of 500 000 kg (1.1 million lb) of uranium oxide contained in a low-grade deposit with high clay content? Confronted with these limited reserves and mineralogical problems at France's St. Pierre du Cantal uranium deposit, engineers adopted a rather unusual mill process to keep capital costs to a minimum. Crushing and grinding were eliminated by using a high pressure monitor to slurry ore directly from stockpiles. After mechanical separation of the high-grade fines from low-grade sand, the sand fraction is washed of clay to increase permeability and then it is heap leached. Fines are sent to agitated vessels for acid leaching, and the pulp from this operation is diluted by pregnant solution from the heap leaching.

Jan 10, 1979

By Roger L. Winter, Borje O. Saxberg

Some form of wage incentives has been used traditionally in the mining industry to determine miners' pay. However, very little is actually known about the administration of such wage incentive plans in mining. As far as the authors know this is the first time a general examination of wage incentive systems as applied to underground mining has been undertaken.* This article reports the results of an investigation pertaining to the administration of wage incentive programs for miners who drill, blast, and load- mainly in underground metallic mining operations. This investigation was conducted to obtain management's views and attitudes towards wage incentives; therefore, the results do not necessarily represent accurately the thoughts of the miners themselves nor those of any organized union of miners.

Jan 10, 1960

By R. G. Robins

The processing of gold bearing sulphide minerals which contain arsenopyrite and various complex arsenic sulphides results in arsenic containing emissions and effluents which are suspect in relation to clean air and clean water standards. Removal of arsenic from gaseous emissions is briefly reviewed. The use of lime to stabilise aqueous residues as either calcium arsenate or calcium arsenite is shown to be inadequate for long term disposal since both compounds are converted into calcium carbonate due to the influence of carbon dioxide in the atmosphere. Mixed calcium arsenate-phosphate residues are similarly unstable, but present better stability than the straight calcium compounds. Alternative disposal methods are reviewed whereby the arsenic is converted to more stable compounds, such as barium arsenate, titanium (IV) arsenate, and arsenic sulphide.

Jan 1, 1984

US 4,183,899 - Flow process for chlorinating ilmenite. A laminar flow of a mixture of ore, a carbonaceous reductant, and chlorine gas or other chlorinating agent is passed through a reaction zone maintained at a temperature of 1350 to 1950°C and a product stream Including titanium tetrachloride is withdrawn from the zone. The atomic ratio of carbon to oxygen in the feed mixture is greater than 1:1, and the molar ratio of chlorine to titanium solids In the product stream is between about 0 5.1 and 2:l. Titanium chlorides and metallic iron are recovered separately from the product stream. J.P. Bonsack, assigned to SCM Corp, Jan. 15, 1980 21 pp. (423-79). Filed. 3-10-78 (885,442).

Jan 1, 1982

By I. J. Corrans

Wet high-intensity magnetic separation (WHIMS) has been successfully applied to the recovery of gold and uranium from the residues of Witwatersrand ores. Good overall recoveries have been achieved for particles as small as 12µ, and finer particles of uranium minerals are recovered when present as inclusions. The best results were obtained with a matrix of soft-iron balls 6 mm in diameter. However, pilot-plant tests drew attention to a major defect of the machine: the matrix could be blocked by wood chips and ferromagnetic particles. This problem was overcome by the incorporation of a modification that allows the balls to be discharged from the rotating annulus. Two full-scale units that incorporate the modification have been installed.

Jan 1, 1980

By A. Sainato, E. Baker, J. Cervik

In Europe, water infusion is used widely to reduce generation of respirable dust during mining. Its use in the US is limited to a few plow operations in the deeper parts of the Pocahontas No. 3 Coalbed. The technology for infusing water into retreating longwalls is described and results of a recent Bureau test in the Lower Sunnyside Coalbed demonstrated dust reductions ranging from 47% to 64%. Because water infusion increases moisture content of the coalbed, face air velocities in excess of 2.5 m/s (500 fpm) are possible, further diluting dust levels before dust entrainment occurs. An economic analysis shows a 23% reduction in operating costs when coal production is increased by changing from unidirectional to bidirectional mining with water infusion.

Jan 1, 1986

By Fred C. Bond

IN crushing and grinding the larger particles are more exposed to the work input. They absorb most of the work and protect the smaller neighboring particles from destructive contact with the crushing surfaces or grinding media. The importance of this exposure differential upon the reduction efficiency and product size distribution has long been recognized. Unfortunately, there has heretofore been no direct method of evaluating it, and such indirect methods as observing the slope of the plotted product size distribution line have been used as an indication. In this presentation the Third Theory of Comminution1 has been used, together with the exponential formula for size distribution, to evaluate the exposure ratio and exposure constant and to illustrate examples of their utility in crushing and grinding applications.

Jan 12, 1957

US 4,192,852-Precipitation of iron values as a jarosite from a sulfate solution obtained as a byproduct in the hydrometallurgical processing of zinc sulfide ore The solution is cooled, partially neutralized, and clarified. The clarified solution is heated to a temperature of 80 to 100°C in the presence of sodium, potassium, or ammonium ions to precipitate substantially all of the ferric iron as jarosite The precipitate is thickened, filtered, and washed The residual solution may be processed for zinc or other nonferrous metal values R V. Pammenter and C J Haigh, assigned to Electrolytic Zinc Co of Australasia Ltd. Mar. 11, 1980. 16 pp. (423-42) Filed: 5-8-78 (903,524). Priority- Australia, 5-9-77 (PD0030) (Drawings below.)

Jan 1, 1982

By J. Redstone, A. R. Laplante

Sidbec-Normines operates six large iron ore concentrate regrinding mills in parallel and open circuit at its Port-Cartier pelletizing plant. Grinding kinetics in these mills were characterized for slurry densities varying between 70 and 89% solids, using a lumped parameter size discrete model. Optimum grinding conditions were encountered at 83.5 to 84% solids. Higher densities decreased the normalized selection function and increased slurry short-circuiting, yielding a sharply coarser mill discharge. At lower slurry densities, the normalized selection function decreased and the mill discharge coarsened slightly. The grinding kinetic model predicted particle size distributions within the mill. These were found to vary significantly from the feed to the discharge end. This is likely to cause nonlinear breakage kinetics.

Jan 1, 1985

By R. B. Sudderth

The recovery of copper by various combinations of processes centered around liquid ion exchange has certainly been accepted as a technically superior entity when compared to the widely applied classical method of cementation. While the technical aspect of liquid ion exchange processes has received much attention and acclaim through actual operating data, in particular the ease of handling solutions, percentage recovery, reduction of pollution, etc., the corresponding economic data has either gone unpublished or has been held confidential. Much of this economic data has now been made available for publication; and with this data, we at General Mills Chemicals, Inc., will attempt to present an accurate economic analysis of some liquid ion exchange plants and an economic comparison between these plants and the typical cementation facility.

Jan 1, 1974

By Howard M. Wells

The investment worth of a mineral deposit can only be realistically evaluated in relation to specified engineering design criteria which fully detail the proposed method of exploitation. The operational design of a mine falls essentially within the technical discipline of the mining engineer, under the constraint that the technical design should be aimed at optimizing the financial attractiveness of the project. In the case of a marginally viable proposition it becomes vitally necessary to identify the best set of design parameters which together will add up to an optimum investment proposal. This paper examines some fundamental logic of optimization for a "wasting asset" type of investment such as a mine, with special reference to the rate of annual production and the strategy of selective mining.

Jan 12, 1978

By R. Kirk

The problems of getting air to the working face of a mine (or perhaps the problems caused by not getting air to the working face) have led to the development of an analogue system in England that reputedly bypasses many of the drawbacks that such systems have encountered in the past. The unit was developed for the Wolstanton Combined mine, an underground operation consisting essentially of three collieries situated in the center of the North Staffordshire coalfield. This combination of workings, which employs a total of eight shafts, brings with it complex ventilation problems, and in order to study these problems and to assist in the control of the established ventilation system, a Ventilation Analogue has been designed and installed to permanently represent the mine's ventilation system.

Jan 4, 1964

By R. H. Wightman, C. D. Chandler, P. B. Nalle

SURFACE quarrying at the Crestmore Div. of Riverside Cement Co. in California was started in 1909. In the early 1920's it was considered that these deposits were nearly exhausted for the equipment available at that time, and in 1927 the company began a block caving system. This mine continued operating until February 1954. In 1941 trucks and crawler-mounted shovels had reached a stage of development that permitted reopening the quarries in conjunction with the underground mine. In 1948 surface reserves and the well developed limestone of the caving system neared depletion. To go deeper with the caving system was unattractive because of the economics, changes in physical structure of the rock at depth, and the perched water table

Jan 4, 1957

By F. D. Rosi, Walter R. Hibbard, R. I. Herron, H. T. Clark, O&apos

Introduction and Previous Work In the search to find a copper-base alloy with high strength properties, it was considered that the addition of a small amount of an age-hardening element to a binary system with useful strength properties might result in a series of alloys of theeretical and practical importance. The copper-nickel system was selected for its basic properties and chromium was added as the age-hardening element in view of the small percentage involved and its decreasing solubility with decreasing temperature. A study of the Cu-Cr binary alloys was undertaken as a preliminary investigation. However, in view of the response of these alloys to heat treatment, the scope of this phase of the investigation was widened.

Jan 1, 1949

By Ben L. Seegmiller

Localized open pit slope failure was avoided as an apparent result of a practical rock mechanics program conducted at the Twin Buttes copper operation. The key to the program was the application of cable bolting, a technique that artificially supports open pit slopes using properly installed post-tensioned cables. As a result of the research and testing program, extensions of the cable bolting principal became significantly apparent. • The economics of artificial stabilization appear to be overwhelmingly favorable, and • Best practical applications are "final" pit slopes, slopes beneath permanent structures and potentially slope failing areas. Success of this research is manifested by the fact that similar stabilization systems are presently under consideration for Twin Buttes as well as other open pit operations.

Jan 12, 1974

By Howard M. Wells

The investment worth of a mineral deposit can only be realistically evaluated in relation to specified engineering design criteria which fully detail the proposed method of exploitation. The operational design of a mine falls essentially within the technical discipline of the mining engineer, under the constraint that the technical design should be aimed at optimizing the financial attractiveness of the project. In the case of a marginally viable proposition it becomes vitally necessary to identify the best set of design parameters which together will add up to an optimum investment proposal. This paper examines some fundamental logic of optimization for a "wasting asset" type of investment such as a mine, with special reference to the rate of annual production and the strategy of selective mining.

Jan 1, 1979