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Samples weighing O·25 g are fused with 1 g potassium hydrogen sulphate, leached with 5 ml. of hydrochloric acid, and then diluted with another 5 ml. of acid. After settling, an aliquot of the clear solution is reduced with stannous chloride, and then a zinc dithiol solution is added to form a coloured tungsten complex which is extracted with petroleum spirit for comparison with standards.Concentrations down to 4 p.p.m. may be analysed at a rate of 100 determinations per man-day of 8 hr.

Jan 1, 1970

Samples weighing 0·5 g are fused with potassium hydrogen sulphate, leached with 4 ml. of 4 M nitric acid and diluted to 10 ml. with water. An aliquot of the clear solution is treated with EDTA, adjusted with ammonia to give a pH value between 5 and 6 treated with cyanide, ammonia, and sodium diethyldithiocarbamate then bismuth diethyldithiocarbamate is extracted with chloroform and the yellow colour is compared visually with a standard series. Alternatively, the bismuth complex may be filtered on a "Millipore" filter and subjected to x-ray fluorescence spectrometry.

Jan 1, 1971

A system of decline mine entries and ore haulages has been designed for the Mt. Windarra mine. This choice was controlled by the nature of the ore- bodies, the mining method chosen and the capital cost of development re- quired for production. Mine entries are being driven 4 metres high and 5.5 metres wide and decline at 11%, to accommodate diesel haulage vehicles of 35 tonnes capacity. The.Mount Windarra haulage system and the design parameters used in its selection and design are discussed, and general design and selection parameters are proposed.

Jan 1, 1973

Bauxite Resources Limited is grade drilling in its Western Australian Darling Range tenements to firm up resource definition and to develop mine plans. The Darling Range bauxite is generally in shallow deposits with minimum overburden. In the northern tenements, the ore is characterised by a higher silica layer which may extend from 0.5 to 1.5 m below, which high grade bauxite is found to a depth of four to 7 m. When grade drilling samples are taken, every 0.5 m and the recovered sample is weighed, logged and bagged. To eliminate splitting errors, the whole sample over the short interval is pulverised. Twinning holes variations are observed when using various drill rigs. Diamond core has been shown to give close to 100 per cent recovery and grades have been verified by digging bulk samples. As such, diamond core is used as the reference. It is intended to include sonic drilling as an alternative to diamond cores. This presentation details and attempts to explain the reasons for the observed variations in the various drilling methods used by Bauxite Resources Limited. This is an ABSTRACT ONLY no paper was prepared for this presentation.

Mar 1, 2010

By Stone AM, Romensky G

The requirement for economic operation of unit trains carrying bulk materials has dictated that rapid and accurate bulk loading methods be provided. The train loading station at Phosphate Hill, built for Queensland Phosphate Ltd. to load rock phosphate, provides this facility and whilst the concept used is not unique, it contains a number of novel features that are considered to advance the "state of the art'' in this field. This paper briefly reviews some alternative concepts evaluated, and describes the design and operation of the scheme ultimately selected as being most appropriate to the project requirements. it is one which utilises a variable speed belt feeder whose speed is controlled in proportion to the weight rate of material moving on the belt as measured against a set point

Jan 1, 1978

By Smith JW

Studies of 13C/12C ratios of carbon dioxide in seam gases and in secondary calcites show that 1. In mines prone to carbon dioxide outbursting, the source of this gas is external to the coal. 2. Faults draining reservoirs of magmatic or primary carbon dioxide, rather than intrusives, are the most likely points of entry of carbon dioxide into mines. 3. The higher the concentration of carbon dioxide in seam gas and the wetter the mine, the lower the likelihood of secondary calcite occurring as a filling in cleats, fractures etc. 4. A -role played by carbon dioxide in promoting outbursting may be the conversion of calcite to soluble bicarbonate, the removal of this in mine water and the subsequent weakening of the resistance of the bulk coal to stress.

Jan 1, 1980

By Vnenk L, Hargraves AJ

Metropolitan Colliery has some areas of roof where immedi- ate support is required in development. The disadvantages of percussive roof bolting at the face have led to recent produc- tion trials with rotary boring and rapid=setting resin anchored roof bolts developed at the Colliery. The three innovations involved are: (1) the wet drilling of small holes with an all- hydraulic, portable rotary boring machine; (2) the rapidity of loading a "point anchored" resin bolt; and (3) the consistently high anchorage strength available. All three innovations provide striking advantages over the previously available alternatives. The greatest disad- vantage - that of cost of resin - is not prohibitive, and there is promise of improvement in the future. There are possibilities of variations of the techniques for special support problems in particularly difficult roofs.

Jan 1, 1971

With some notable exceptions, marine placers located just below, or just above, present sea level, are responsible for much of today's production of detrital ilmenite, rutile, zircon, and other minerals of value. The purpose of this paper is to discuss the paleogeographic and paleo-oceanographic factors which may have determined the location of presently submerged marine placers. These factors-include changes in sea level, burial by recent marine sediments, stream capture and other i changes in drainage patterns, and recent changes in climate. Selected geologic situations in the Yellow Sea off the coast of Korea, in the Atlantic Ocean off the coast of Portugal, in the Bering Sea off the coast of Alaska, and in the Arabian Sea off the coast of India, will be used to illustrate the author's point of view.

Jan 1, 1980

By M L. Habner, S D. Munro

In a gold CIP/CIL circuit, adding new circuit water to a final tails thickener and then directing the thickener overflow to the head of the circuit significantly reduces the cyanide concentration at the TSF discharge spigot. The new water is used to dilute the final tails. The dilution and recycle of the tails in this manner may have the added benefit of reducing reagent consumption, in some cases to the point where the reagent savings justify the expenditure and Cyanide Code compliance is achieved at no extra cost. Potential circuit configurations and water recycles can be modelled by splicing a flowsheeting and thermodynamics package, such that changes to the composition of the water can be reduced to chemical speciation with a Gibbs free energy minimisation enabling a complete understanding of the circuit water chemistry.

Jan 1, 2007

Self Advancing or "Poweredtt supports are a successful means of supporting roof and designs have reached the stage where adequate support capa- bility is available for all conditions. Some designs have resulted in equipment being too difficult to transport underground and too complex to maintain. Current trends are reducing those problems and simplicity in hydraulic systems is now the keynote of both supplier and user. There is a good possibility that the "Shield-Chock" support will be the universal design of the future. So-called t'shortwall supports" have been developed to the point where they can be applied with a high degree of confidence to conditions of great variety. Develop- ments by manufacturers and practices of users related to maintenance should result in consistent achievement of designed performance.

Jan 1, 1974

By K Brown, J Webster-Brown

Coal mining activity first began on the West Coast in 1864 and has since led to the exposure of large areas of coal and host rock to chemical weathering. These exposed abandoned workings have led to the formation of acid mine drainage, which flows into selected rivers and streams impacting on the natural environment. A previous study conducted for the West Coast Regional Council identified four catchments receiving mine drainage which had elevated arsenic concentrations. The aim of this research is to expand on this initial study by determining the spatial distribution and attenuation of the arsenic within the sediment and water column in each stream of concern. Cannel Creek is influenced from drainage from the Bellevue coal mine adit and exhibits a low pH of ~3, elevated sulfate concentrations and high arsenic and iron concentrations in the sediments. This pattern is repeated in the Rapid Stream and Soldiers Creek catchments, which are also affected by adit inflows from the Sullivan and Blackball coal mines respectively. Soldiers Creek also has significantly high arsenic in the waters, with an accompanying pH of ~5.5. Snowy River exhibits a similar trait with a pH also of ~5.5, but with very low sulfate concentrations. Arsenic concentrations in the waters are consistently around 30 ppb, with sediment concentrations up to 900 ppm. These sediment values might be partially attributable to the operation of the Snowy battery gold ore production facility, but the consistently high As concentrations in the water column and in the sediment upstream of the battery have an as yet unconfirmed source.

Jan 1, 2002

The Kyaukpahto gold deposit is located at latitude 23¦ 47Æ 55" N and longitude 95¦ 56Æ 35" E in the Kawlin-Wuntho district, Sagaing Division, Myanmar. Gold mineralisation is hosted in sandstone of the Male Formation (Eocene) and occurs as stockworks and disseminations. The high-grade gold mineralisation is locally concentrated in a breccia zone. The gold deposit is closely associated with a NNE-SSW trending fracture system that forms tensional open fractures. These tensional zones are thought to be directly related to the Sagiang transfer fault system that experienced several hundred kilometres of northward dextral movement during the post-Upper Miocene. Major sulfide minerals are pyrite and arsenopyrite with minor galena, chalcopyrite and sphalerite. Gold mineralisation is associated with intense silicification, sericitisation and argillic alteration. Primary Type I fluid inclusions in the quartz from the mineralised zone are 5 to 15 ¦m across and yield homogenisation temperatures of 239¦ - 310¦C and salinities of 1.2 - 10.9 wt per cent NaCl equivalent. Laser Raman spectroscopic analysis indicates the presence of CO2 and CH4 in Type II fluid inclusions. Sulfur isotope analysis of disseminated pyrite in the ore zone by the laser ablation method indicates d34S values from -5.48ë to +5.53ë. The geology, alteration, ore mineralogy, fluid inclusion microthermometry and sulfur isotope data of the Kyaukpahto deposit are consistent with an epithermal ore deposit model for the deposit. However, the presence of CO2-liquid bearing fluids and the detectable CH4 in the gaseous phase of the fluid inclusions conflict with a typical epithermal origin for the Kyaukpahto deposit. The host siltstone and mudstone sequence, trace element geochemistry, and the disseminated nature of sulfide and gold mineralisation are also common characteristics of a sedimentary rock-hosted gold deposit, and these features may indicate a Carlin-like affinity. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

Computer simulation of the control systems for the heavy media coal washing process have been presented in this paper. The simulation model applies the Simulink module of the Matlab 5.1 software package and allows monitoring of variations of a

Jan 1, 1998

The seam gas content at Westcliff Colliery is 12-15m3/tonne of coal.Composition ranges from 99% CH4 to 52% C02 in one area. Desorption rates are proportional to gas contents and CH4 is preferentially desorbed. A crushed zone of reduced permeability advances with the face - at Westcliff ribside crushed zones are 2.5 to 6.5m wide. Poor strata control widens crushed zones. 12 months of pre-drainage allowed 2 heading development and longer pillars to be used in a virgin area instead of 3 or more headings without drainage. Machined coal may lose as much as 1.6m3/tonne being conveyed out of Westcliff Colliery. Experience differs from mine to mine. Permeation is affected by time, strata movements, changing water content, and changing stress. Permeabilities vary from lOmd for Pittsburgh Seam to less than 1 and for the Bulli Seam. All these data and differences await further investigation.

Jan 1, 1982

By Higuchi K, Sekimoto Y

In this report,the results of the large diameter drilling tests in coal seams assisted with water jet are described. The stress relief in coal seams by this new method is as effective as by the conventional method and the penetration speed by this method is 1.5 times as fast as by the other method. 1 Introduction The average mining depth of Japanese coal mines has already attained about 700m from the surface. Almost all coal mines are suffered from occurrence of coal and gas outbursts. To prevent outbursts, some countermeasures are taken generally. In particular, large diameter stress relief borings have been carried out quite often at Akabira coal mine located in the northern part of the Ishikari coal field in Hokkaido,JAPAN. These borings have had successful results but the drilling work of such large diameter

Jan 1, 1987

By Yoshii Y

Many kinds of shield machines are being driven in the soft ground of Tokyo metropolitan area. Tunnel alignments for underground power transmission lines are generally planned to pass under public roads where facilities, especially life-line facilities, are densely located. Therefore, it is frequently required to drive the shield machines along very sharply curving routes. This paper reports on the performance of the new shield machine - the Sharp Curve Excavation Shield Machine - developed by Tokyo Electric Power Co., Inc., which can freely drive along a much sharper curve than conventional machines. Some of features of the developed devices of this machine are, maximum flexing angle of 6.5 degree in all deirection at the middle of shield body, maximum bending angle of 3.5 degree in all direction at the cutter disc, and so on. This shield machine can there- fore drive along curve of minimum radius 15m. The machine was confidently applied to the const- ruction of tunnel in soft clay strata at N values 2 to 5. Outer diameter 3.7m. Length 202m. Horizontal curve; radius 15m, length 20m x 2. Vertical curve; radius 30 m, inclined driven up 29%. The behaviors of the shield machine, segments and surrounding ground were monitored during construction for safety and efficiency check of this machine.

Jan 1, 1987

By Lauha E. A

The Goldstrike Mine is in Eureka County, Nevada, U.S.A., approximately 23 miles northwest of the town of Carlin. The mine is at the north end of the Tuscarora Spur of the Tuscarora Mountains at elevations of 5,300 feet to 5,950 feet. It is part of the Bluestar/Goldstrike subdistrict of the Carlin Trend, a northwest alignment of sediment hosted, disseminated gold deposits. The Carlin Trend includes over 15 major gold deposits with production, reserves and geological resources of approximately 65 million ounces of gold (Figure 1). In the Bluestar/Goldstrike subdistrict, there are seven major deposits; Betze, Lower Post, Post, Genesis, Bluestar, Purple Vein and Deep Star, plus numerous smaller deposits (Figure 2). Production, reserves and resources for the subdistrict are approximately 40 million ounces. Betze and Purple Vein are located on property controlled by Bamck Goldstrike Mines and Bluestar and Genesis on Newmont Gold property. Post, Lower Post, and Deep Star occur both on Barrick and Newmont Property.

Jan 1, 1991

Cable bolts have been used extensively in the development of the footwall of the Mt Whaleback Mine as a part of the ground improvement program since 1986. High tensile seven wire stress relieved steel strand similar to that used in pre-stressed concrete and grouted in place with sulphate resistant cement have been employed for rock-mass reinforcement.Most of the footwall is developed in Mt McRae Shale which contains a 20 m thick pyritic shale layer 14 m below the ore/waste contact. Due to extensive folding of the footwall rocks, the pyritic shale layer regularly occurs on, or close to the pit slope. Rain water run-off seeping through pyritic shale becomes acidic to the extent where its pH value can be as low as 1.5.

Jan 1, 1992

By Player R. L

Measurements of the rate of PbO reduction from high lead metallurgical slags were made under laboratory conditions using graphite, a CO-50%CO2 gas mixture and metallic iron as reductants. The results show a transition in rate-controlling step at low PbO contents (i.e. 6 wt.% PbO). At medium to high PbO contents in the slag, the reduction rate was found to be strongly affected by the slag chemistry, temperature and reductant type. The effect of stirring and hence mass transfer in the slag phase on the reduction rate of PbO was found to be insignificant at medium-high PbO contents. Attention is drawn to the importance of chemically controlled reaction rates at the slag-gas interface. Parallels between these results and test work on a 5 tph scale have been briefly drawn.

Jan 1, 1989

By Woodcock JT, La Broody SR

As part of a project on the application of thiourea leaching to a variety of Australian ores, the systematic variation of pH, redox po- tential, and thiourea concentration were in- vestigated on an oxidized gold ore from the Nevoria mine, WA. Stirred open beaker tests were conducted with a pH-stat and Eh-stat system to automati- cally control pH and redox potential at selected values, while thiourea concentration was main- tained manually. Increasing the acidity of the leach liquor from pH 3.6 to pH 1, increased the gold extrac- tion from 37 per cent to over 90 per cent in S h, but there was only a limited improvement below pH 1.5. Silver extraction and thiourea consumption increased as the acidity was in- creased. Increasing the redox potential from 150 to 200 mV (i.e. potential of Pt electrode vs SCE) increased the initial rate of gold and silver extraction, but the effect on cumulative gold extraction by 5 h was slight. Thiourea consump- tion was greatly increased as the redox poten- tial was increased. An increase in thiourea concentration from 1.2 to 4.8 per cent increased the initial rates of gold and silver extraction, but, as for the change in Eh, the improvement in cumulative ex- traction by 5 h was marginal. Thiourea consump- tion increased with thiourea concentration.

Jan 1, 1984