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The development of the Ballarat goldfield and of the city of Ballarat are a significant part of the history of the Australian mining industry. Important developments in technology, legislation and labour relations made their first Australian appearance in Ballarat. The growth of the city and its survival after the closure of the mines provide an interesting case study in the benefits flowing from a vigorous mining operation. The failure of the mines can be attributed to rising costs of materials and labour and declining manpower productivity at a time when the price of gold was not free to respond to changing market conditions. The curtailment of exploration programs and increasing labour unrest resulted from this situation, and made the closure of mines inevitable.

Jan 1, 1982

By J. F. Labuz

Fracture tests were conducted on subsize specimens of Charcoal granite to demonstrate that the extent of the nonlinear region at the crack tip can be significant. The model of the fracture process considers an effective crack length as a traction free portion plus a process zone where closing stresses act; this zone is identified by microcracking and interlocking. A singularity is allowed at the effective crack tip. The effective stress intensity factor is the superposition of the stress intensities due to the effective crack and the process zone. By assuming that the closing stress is a linear function, it is shown that a process zone length of approximately one-third the effective crack is needed to match the compliance-determined crack length.

Jan 1, 1984

By Edward Sampson

Despite the many industrial uses, the world market for silver as a commodity is far from free, being dominated by the U.S. Government both through acts of Congress and by policy of the Treasury Department. This discussion will consider aspects of supply, demand, and price with a view to the future. Changes in Sources of Supply: The world's peak production of silver, 278 million oz, was in 1937. In the 1850's world production was about 30 million oz, having risen from a yearly average of 11 million oz for the first half of the century. From 1860 to 1940 there was a steady rise, broken only by World War I and the depression of the early 1930's.

Jan 7, 1960

ARIZONA Tucson University of AriZona, Mining Engineering Society. B CALIFORNIA Berkeley University of California, Mining Asso. B University of California, Library. B & T Los Angeles Chamber of Mines and Oil. B Southern California Local Section. T Public Library. B & T Oakland Oakland Free Library. T San Francisco California State Mining Bureau. T Mechanic's Merchantile Library. B Mining and Scientific Press. B Stanford University Stanford University Geological and Mining Society. B San Diego Public Library. B COLORADO Boulder University of Colorado, Library. T Denver Bureau of Mines. B Colorado Scientific Society. B Mining American. B Denver Public Library. B & T Golden Colorado School of Mines Magazine. B Colorado School of Mines Library. T Colorado School of Mines Scientific Society. B

Jan 1, 1923

By V. L. Stolyarova

The high-temperature Knudsen effusion method was used to study partial pressures of vapour species, activities of components and the Gibbs free energies in the DyF3-Dy2O3 system at the temperature (1357±5) K. Partial pressures of vapour species were obtained by the ion current comparison method, with the DyF3 partial vapour pressure over pure DyF3 as a standard. The equilibrium constant of the gaseous reaction DyF3 + DyOF = Dy2OF4 is evaluated. Thermodynamic data obtained are in a agreement with the available phase diagram of the DyF3-Dy2O3 system. Results of the present study illustrate the negative deviations from the ideal behaviour in the system.

Jan 1, 1997

By Leon O. Hart

The nickel-chromium alloys of importance are those containing iron and those free from iron. The most important alloys containing iron, with regard to high tonnage, are the nickel-chromium steels. Straight nickel steel was introduced about the year 1889, but it was not until 1895, when it was found that the addition of chromium greatly increased the strength and resistance to shock, that nickel-chromium steels came into use. The three types of nickel-chromium steels developed at this time were: Type 1, containing 3.,50 per cent. nickel and 1.50 per cent. chromium; type 2, containing 2.00 per cent. nickel and 1.00 per cent. chromium; and type 3, containing 1.50 per cent. nickel and 0.50 per cent. chromium.

Jan 1, 1921

By M. M. Botz

Cyanidation tailings disposed of in a surface impoundment experience a loss of cyanide due to natural attenuation, which frequently reduces the cyanide concentration to very low levels. Quantifying cyanide losses in terms of impoundment geometry, local weather conditions and feed-solution chemistry has been largely empirical in spite of the fact that, in many cases, mining operations rely on surface impoundments to reduce cyanide to below an internally regulated concentration or below an effluent limitation. To permit a quantitative evaluation of cyanide losses in an impoundment, a computer simulation was developed to estimate the losses of free, weak acid dissociable (WAD) and total cyanide due to dissociation, photolysis and volatilization. Results of the model are compared with data collected for a North American tailings impoundment in 1998.

Jan 1, 2000

By L. A. Morley, W. T. Parry

Laboratory prepared clay-quartz sand samples and fault gouge from an open pit slope undergoing plane-type failure were tested in the laboratory to determine potential mining applications of electroosmotic stabilization and to provide a better understanding of electrochemical hardening. Experiments with very low current densities and free access of electrolytes to both anode and cathode showed an increase in cohesion. Cohesion in a fault gouge increased by 9.3 to 113%, depending on location with respect to the electrodes. For this, power consumption was equivalent to 0.727 watt-hr per cu ft (25.69 watt-hr per cu m). Regions of electrochemical hardening were determined by pH and the anolyte used. Electroosmotic stabilization appears as a reasonable solution to some types of mining problems.

Jan 1, 1975

Robert H. Richards, Boston, Mass.: Mr. Goodale calls attention to the difficulty of obtaining clean tailings from the jigs which are fed by the spigots of the hydraulic separator. This difficulty is universally encountered. The Lake Superior copper mills practically overcome it by running the beds of those jigs loose, carrying into the hutch all of the available copper and some sand. These hutches are again jigged upon threesieve Collom jigs, where the treatment is very slow and gentle; and on the successive jigs lighter and lighter bedding is used. The last sieve is run thin enough to let some sand into the hutch. With these precautions most of the free copper is extracted, as well as a fair proportion of the included copper.

Jan 1, 1897

By Robert H. Richards

Very little has been published recently on this subject in the mining journals or proceedings of societies. The attention of experts has been diverted perhaps by the demands for pan amalgamation of refractory ores. Yet free milling ores occur in many localities, and it may be interesting to have on record some data as to details of running a small test-mill, especially as details of results do not seem to be accessible to stndents and investigators. Küstel, in 1863, under battery amalgamation, dismisses the subject by stating that "amalgamation on copper-plated platforms, troughs, and other copper fixings" is " very imperfect, and mostly abandoned." J. Arthur Phillips says, in 1867, under placer mining : " A well-amalgamated copper plate is considered as effective for

Jan 1, 1880

By Robert H. Richards

VERY little has been published recently on this subject in the mining journals or proceedings of societies. The attention of experts has been diverted perhaps by the demands for pan amalgamation of refractory ores. Yet free milling ores occur in many localities, and it may be interesting to have on record some data as to details of running a small test-mill, especially as details of results do not seem to be accessible to students and investigators. Küstel, in 1863, under battery amalgamation, dismisses the subject by stating that "amalgamation on copper-plated platforms, troughs, and other copper fixings" is " very imperfect, and mostly abandoned." J. Arthur Phillips says, in 1867, under placer mining : A well-amalgamated copper plate is considered as effective for

Jan 1, 1880

Objective Develop field measurement and computer modeling methods to predict the potential for hang-ups and structural failures in underground mine ore paws. Background Analysis of Mine Safety and Health Administration (MSHA) accident statistics has identified ore pass hazards as a significant safety problem in underground metal mines in the United Stales. Recent ore pass failures have underlined the lack or ore pass design methods ant1 standards available to both MSHA and mine engineers. Injury and fatality data for the 20-ycar period between 1975 and 1095 show that nearly 75% of the injuries were directly or indirectly related to pulling or freeing ore pass chutes, the use of hand tools, falls or broken rock, and structural failures or chutes or gates and ore pass walls.

Feb 1, 1998

By F. M. Doyle, Robert G. Robins, E. Peters

Stability diagrams for the Cu-S-H2O system have been widely applied over many years. Stability diagrams for aqueous systems generally, have been generated by computer, but with the programs for Potential-pH diagrams in particular, a common routine leads to error in multi-element systems. In this paper these errors, and some misinterpretation of diagrams are considered. In most of the published diagrams for the Cu-S-H2O system there has been no account of the sulfide complexes of copper. Here, the free energies of formation for the various species in the system have been re-evaluated for consistency, and some diagrams for the Cu-S-H2O system ( generated with the program DIASTAB Vers.5 ) are presented.

Jan 1, 1993

Improve mine refrigeration system efficiency while providing free electrical energy to mines. Approach Convert the potential energy of incoming mine water falling down long vertical shafts into electrical energy by means of a turbine-generator system located at the bottom of the mine shaft. How it Works Converting the energy of falling water into useful work is a well-developed engineering concept. Water flowing down long vertical pipelines into deep mines develops high pressure that can be used to operate a turbine-generator system at the bottom of the pipeline. A thermal energy recovery system of this type offers three advantages: 1. In systems without turbines, the potential energy of the water is converted to heat. The water temper-ture will automatically

Jan 1, 1985

By Turner T. M, Jorgensen F. R A

The tendency of the concentrate to ignite was studied using four techniques, namely, laminar flow furnace, fluid bed, thermal analysis and boat-in-furnace. Exothermic activity occurred at two temperatures: minor activity in the vicinity of 200¦C, major activity at 330-350¦C. The low temperature reaction was due to the ignition of a small amount of free sulphur while the major activity was associated with the ignition of the sulphide minerals, notably pyrite. To avoid ignition of the sulphide minerals, the gas temperature should not exceed 300¦C and the oxygen content of the gas phase should be as low as possible. It was shown that little of the arsenic in the concentrate entered the gas phase during drying.

Jan 1, 1987

Gold mineralisation at the Enterprise Mine, 230 km south of Darwin, occurs within folded and metamorphosed sediments of the Lower Proterozoic Burrell Creek Formation adjacent to the Cullen Granite. The mineralised zone, which occupies an area of approximately 800 m x 300 m is local- ised by a moderately tight, upright symmetrical anticline which plunges shallowly southwards. The anticline has been disrupted by numerous faults on which the maximum movement is 40 m. Gold is associated with quartz and sul- phide veins which are present as saddle reefs, inter-reef veins and fault controlled reefs. it occurs within the veins or their alteration haloes, either as free gold (2 - 50 per cent of total gold content) or intimately associated with sulphides, principally arsenopyrite and Pyrrhotite.

Jan 1, 1984

By Best R, Poulos H

This paper discusses the results of an Australian Coal Association Research Program project into the development of a routine analytical design method for roof support in underground mines. Simple design tools have been developed using a combination of elastic solutions, free body diagrams, and pile theory. An approach to the design of roof support in layered strata based on the ability of bolts to resist shear stresses is outlined. It is shown that pre-tensioning and angled installation are effective ways of increasing the effectiveness of bolts in such a situation. In highly stressed strata, macroscopic failure is predicted and a design based on the support of surcharged rock wedges is proposed. The methods are applicable to both coal and metalliferous mines.

Jan 1, 1995

Utah Development Company operates a mine at Blackwater with a present annual production of 4 000 000 tonnes of coking coal. Mineable seams outcropping on the company's lease are part of the Permian Mammoth Rangal Coal Measures. Current operations are based pre- dominantly on the Main Lower seam. Coal quality variations occur along the seam strike, in the direction of seam dip, within the seam plies and in isolated anomalous areas. Raw coal of non-specification quality is washed to reduce ash and sulphur and to improve the free swelling index. Raw coal meeting specification quality is sent directly to product, by-passing the washplant. Careful attention to mining, coal preparation and product blending is necessary to ensure that the combined product meets specifications.

Jan 1, 1974

The South Ghorveh Batholith (SGB) and the Almoughlagh Batholith (AB) intruded the volcanosedimentary sequence of Songhor Series (Triassic-Jurassic), during the Oligo-Miocene orogenic phase. The granitoids of the AB belong chiefly to the quartz-syenite and syenogranite clans while those constituting the SGB can be generally characterised as quartz monzonite varying towards quartz monzodiorite, and diorite. Granitoids constituting both the batholiths are low in free quartz, and possess characteristics of the æmagnetite seriesÆ, mostly of I-type, metaluminous to marginally peraluminous and calk-alkaline type. Adjacent to them are located the magnetite skarn deposits of Baba Ali and Gelali. In the light of petrography, geochemistry, mineralogy and field geology investigations they could be classified as Fe-skarn and mainly bear characteristics of calcic skarn deposits.

Jan 1, 2005

By Marco D. Boscardin

During subsidence, the ground surface may settle, change slope, change curvature, go into tension, and/or go into compression. In response to these ground movements, buildings and buried utilities in the subsidence area may settle, tilt, bend, distort, and sustain extension, compression and/or torsion. In order to develop measures to protect existing structures and utilities, or to design new structures and utilities to withstand potential movements in areas of subsidence, it is necessary to understand the interaction between the ground and the building or buried the utility. This paper reviews subsidence-induced ground movements, how these ground movements are transmitted to and accommodated by buildings and buried pipelines, and how these structures may alter ground movements relative to free field subsidence-induced ground movements.

Jan 1, 1986