Search Documents

By R Pie, J Crusius, P Whittle, J J. McNee

The Main Zone and Waterline pit lakes at the Equity Silver Mine near Houston, BC (Canada) are the sites of an ongoing three-year government- and industry-funded research program. In order to assess the feasibility of various bio-remediation strategies, field-scale manipulations were conducted using enclosed mesocosms (limnocorrals). Two manipulation strategies were tested: addition of algal nutrients (phosphate and nitrate) to Main Zone Pit surface waters; and addition of algal nutrients (surface waters) and dissolved organic carbon (deep waters) to the Waterline Pit. Nutrient addition was conducted in order to stimulate algal production and enhance metal scavenging by biogenic particles, while dissolved organic carbon (ethanol) was added to increase oxygen demand and foster the development of sulfate reduction in pit bottom waters. Fertilisation resulted in rapid growth of natural phytoplankton populations in the surface waters of both pits. In the Main Zone Pit, the stimulation of algal growth resulted in the pronounced removal of both dissolved and total metals (Zn and Cu) from surface waters, with higher rates of metal removal being observed at higher nutrient additions. Metal removal could be attributed to the scavenging of dissolved metals by biogenic particles and subsequent particle settling. A similar pattern of removal from surface waters was observed in Waterline Pit (Zn and Cd). The addition of ethanol to deep waters in Waterline Pit was effective in promoting sulfate reduction in the lower layer. The development of reducing conditions resulted in near-quantitative removal of dissolved Zn and Cd, presumably as secondary metal sulfides. Iron, As and Ni profiles in Waterline Pit exhibited no evidence of removal from either surface waters or bottom waters. Collectively, the results demonstrate that the passive forms of bioremediation tested in these pit lakes may be effective for whole pit-lake remediation.

Jan 1, 2003

By Ainslie LC, Toens PD, Andreoli MAG

The geological and economic aspects of the known deposits of uranium in southern Africa are described. Processes influencing uranium mineralisation in the relevant geological environments are elaborated upon in order to define fundamental characteristics of mineralisation in the sub-continent and identify potential areas for the location of new deposits. Several areas, namely the Damara orogenic belt and its extension in Zambia and Zaire, the Bushveld zone, and the terrains of uranium fertilisation from the mantle have a high probability of hosting uranium deposits which are yet to be discovered. Uranium resources of the southern African region have been estimated and production forecasted to the year 2000. This geographic region contains one quarter of WOCA's resources in the Reasonably Assured Resources and Estimated Additional Resources - Category I exploitable at less than 130/kg U. On this resource base, it has the potential to maintain its position as the leading exporter of uranium in the world with a production of 13 350 t U308 by the end of the century. Zambia and Zaire are expected to join South Africa and Namibia as uranium producers in the next decade, with their combined share of projected production being in the order of 10%.

Jan 1, 1986

The use of coal as a fuel for heat and power generation has a long history. During the nineteenth century most of the present combus- tion technologies were pioneered, as shown in Table 1, This period was associated with the "golden age" of coal and its contribution of almost 80% of the world's energy demands in the early,1900s . The decline in the use of coal has been due to the transfer of the heavy transportation area to diesel power, the elimination of coal as a household fuel and the substitution of oil for coal in power plants. Coal remains the major fuel for the electric utility industry and the present paper will be concerned primarily with that application. Table 1 outlines the development of coal tech- nology with the parallel understanding of coal as a material and its behaviour during combus- tion. Clearly many developments in combustion technology have occurred in this century, although most of the processes had been invented in the nineteenth century. Also, the great expanse in coal research of the past few decades has led to a greater understanding of the coal combustion process.

Jan 1, 1987

By A D. Paktunc

The surface reactivity of underwater deposited, high-sulfide copper mine tailings was evaluated under fresh and saline water cover conditions by measuring the surface and pore water quality as a function of time. The experiments were conducted in aquarium type lysimeters having a shallow, well-aerated water cover up to approximately 0.25 m over the tailings. Natural lake water was used for the fresh water cover and seawater for the saline water cover scenarios. The tailings showed significant surface reactivity and oxidation under both fresh and saline water cover conditions. The surface water quickly became moderately to highly acidic, and surface oxidation of the tailings resulted in increased dissolution and release of sulfates, iron (total), calcium, magnesium, aluminium, manganese, copper, nickel, zinc, lead, cobalt and silicon to the water covers. A moderate to slightly increased loss of total sulfides, including pyrite, chalcopyrite and sphalerite, occurred in the tailings surface layer to a very shallow depth. In comparison to the fresh water cover, the complete acidification of the saline water cover was delayed by approximately 30 - 40 days because of its additional available alkalinity. Whereas the rate of surface water acidification and release of aluminium and silicon were moderately reduced under saline water cover conditions in comparison to those for the fresh water cover, the release of calcium, magnesium, iron (total), copper, nickel, lead, zinc, sodium and potassium were enhanced. The mass transfer fluxes for dissolved copper, nickel lead, zinc and iron (total) from the tailings substrate to the surface water cover following surface water acidification were higher by 50 per cent or more in the saline water cover than those in the fresh water cover. This release was also reflected in moderate loss of pyrite, chalcopyrite and sphalerite in the very shallow upper surface layer of the tailings at the tailings-water interface, although the loss of pyrite in the surface layer was less pronounced. In both cases, the dissolution of aluminosilicate minerals moderated, to a certain extent, pH and acidity in the water cover.

Jan 1, 2003

By L C. Thompson

This paper examines six sites in Northern Nevada where soils and groundwater have been contaminated with petroleum hydrocarbons and/or organochlorine compounds. All six of the sites studied are located in an arid, highly mineralised area of the Great Basin. As a part of the original geochemical investigation to determine the applicability of biodegradation in the remediation of petroleum impacted soils and aquifers extremely high levels of uranium, vanadium and molybdenum were detected in the anaerobic groundwaters associated with some of the hydrocarbon plumes. Some groundwater uranium concentrations exceeded 7 ppm while vanadium and molybdenum concentrations reached almost one ppm. The bioleaching appeared to be most effective under methanogenic conditions and was noted in both high sulfide and low sulfide environments. Background concentrations of uranium in the formation were measured between 6 ppm and 109 ppm and highly dependent upon depth with the highest levels being found in association with evaporites. Unlike uranium, vanadium tended to concentrate in free-floating organic fractions reaching levels as high as 2000 ppm in the layers of jet fuel floating above the groundwater. Molybdenum was the most resistant of the three metals to bioleaching.

Jan 1, 2004

Modern plate tectonic reconstruction of Mexico and Central America shows that the southeast-extend ing Precambrian backbone of Mexico, together with the east-flanking accreeted Huastecan (Appalachian-Caledonian) orogenic belt, are geotectonic elements practically absent in Central America, except west-ern and northern Guatemala and Belize, and contrib-uted little to the mineral potential of the entire region.The gradual accretion of the Cordilleran oro-genic belt took place against the western-south-western margin of the Precambrian backbone, and its consolidation required several tectonic events from the medial(?) Paleozoic to the end of the Mesozoic. The striking features of this "long-lived" orogenic belt are the massive sulphide min-eralization in the upper Paleozoic eugeoclinal as-semblage, the widespread gold occurrence in quartz veins in the lower Mesozoic volcanics and related intrusives, the carbonate-hosted silver-bearing lead-zince deposits of the Mississippi Valley-type (or Pine Point-type) around carbonate banks within the Lower Cretaceous back-arc miogeocline, that de-veloped over the Precambrian backbone and deeply-eroded Huastecan orogenic belt, the massive sul-phide (Pb-Zn) deposits in the Upper Jurassic-Lower Cretaceous sequence, transitional from miogeocline to eugeocline, which carry high grades in silver, and the iron deposits in this transitional facies, which are described in the literature as related to dioritic intrusives of Late Cretaceous age. Central America, south and southeast of the Mota-gua-Polochic fault system, forms part of the in-ternal zones of this orogenic belt.

Jan 1, 1990

The Key Centre for Mines consists of the School of Mines of the University of New South Wales and the Departments of Geology and Civil and Mining Engineering of Wollongong University. The Key Centre for Mines/International promotes, markets and develops overseas activities in applied geology, mining engineering, mineral processing and extractive metallurgy specifically in response to the perceived needs in the region for mineral resource and other related earth-science based development. the Key Centre for Mines/International will be involved in the overseas marketing of formal courses; special training activities such as short courses and in-house programs; technical and educational consultancy; research and development projects, and in the establishment of regional links through twinning, exchange and various network arrangements with other organisations in the region. Activities which are now being developed include a training program for Korean mining engineers and geologists, teaching and curriculum development in the Mineral Resources Engineering Faculty of the University Sains Malaysia and a staff development proposal for the Department of Geotechnology of Khon Kaen University, Thailand

Jan 1, 1990

Structural assemblages of veins, shear zones, and wallrock alteration zones arising from fault-valve action on steep reverse fault systems are reviewed using observations from mesothermal gold-quartz lodes in the Archean Yellowknife, Abitibi, and Yilgarn greenstone belts of Canada and Western Australia, the Cretaceous Mother Lode system in the Foothills Metamorphic Belt of the western Sierra Nevada, California and the Victorian goldfield hosted in a folded quartz-turbidite succession of Paleozoic age in Australia. Despite differences in the host rock assemblages, the deposits have many structural characteristics in common. These form a useful exploration guide when re-evaluating comparable, but poorly described gold-quartz vein systems such as those in the Reefton area of New Zealand.

Jan 1, 1992

By J Zhiming, X Qian

All high stopes and pillars in Anqing Copper Mine were extracted by use of large-diameter longhole mining method. The height of stopes was 120 m. The forced mining was the leading concept that the safe and efficient operation was carried out in this mine, while the mining production was faced with the major technical problems on the stability of both primary ore pillars produced in the first-step stoping of stopes and the cemented fillbody on two sides of stope in the second-step stopping of pillars. Starting with mining technology, the authors emphatically describe the test results obtained in Anqing Copper Mine and make an approach to the deployment prospects and development trend of large-diameter longhole mining technology in China underground metal mines.

Jan 1, 2000

As the gold price, and consequently ore reserves, improved in the late 1970's, a programme of upgrading the gold recovery circuit at the Phoenix treatment plant at Central Norseman was initiated. The introduction of oxidised ore with a high clay content from the North Royal open cut caused a reduction in thickening and filtering capacities, which in turn restricted plant throughput and increased gold losses in the residue solutions. Test work into alternative washing facilities showed that the installation of a five stage counter current decantation system would restore throughput and reduce soluble gold losses. Installation of the system achieved the objectives of increased plant tonnage, increased proportions of the high grade oxidised ore in the mill feed and decreased gold losses in the residue waters.

Jan 1, 1978

By Carlson BL, Overton DD

This paper compares the designs of heap leach facilities for four precious metal mining projects in the southwestern United States. These four proposed projects are of small-to medium-size relative to other operating mines in the United States, and are either permitted or in the final stages of permitting. The differences and similarities in the heap leach facility designs are compared with respect to site conditions, operating conditions and regulatory requirements. This comparison provides a summary of the state-of-practice for heap leach facility design in the southwestern United States and identifies current issues in project development and process material containment.

Jan 1, 1997

Rifting and transfer faulting in the Late Cretaceous to Early Tertiary resulted in the formation of the Bundaberg Trough and Wallaville Basin and deflected the margin of the Maryborough Basin southwestward between the Kolan and Burnett Rivers. During the Cainozoic, three periods of volcanic activity occurred in the Bundaberg-Gin Gin area. The oldest of these periods, Paleocene to Early Eocene, resulted in the outpouring of tholeiitic lavas. During the Late Miocene to Pliocene, undersaturated alkali basalts generated at depths of from ca. 35 to 55 km were emplaced. These lavas were followed in the Pleistocene by the alkaline Hummock and Berrembea Basalts. The loci of eruption of all of these lavas were controlled by the intersection of the transfer fault system and pre-existing north to northwesterly trending faults in the Bundaberg-Gin Gin area.

Jan 1, 1990

By Lu T. K

A new type of rockbolting system, the self drilling rockbolt, has been studied to develop a 'single pass' bolt for use in rockbolt installation in underground engineering. This single pass bolt forms the basis of a Rapid Face Bolting system which will reduce the amount of time spent in securing a roof during the operation of a continuous miner in the development of a panel.The installation efficiency and anchorage tests were performed in the laboratory on the self drilling bolt and the traditional resin anchorage. bolt. The results of both bolts are cmmnared.

Jan 1, 1993

An account of milling "methods and costs at Mount Isa Mines Limited up to the year 1938 has been published. The present paper outlines the methods since adopted in the milling of lead-zinc ores and presents a description of the equipment now being provided for the milling of copper ore.The programme approved for the mining, milling and smelting of both lead-zinc and copper ores involves the milling 9f 50,000 tons of lead-:-zinc ore and 35,000 tons of copper ore per month.The crushed ores will be delivered to the surface from alternate levels through No. 2 Ore shaft and conveyed to their respective crude ore bins at the crushing plant. The ores will be crushed and milled in separate circuits in common buildings and the tailings will be stored on a common tailings dump. The water services to the two circuits will be separate.LEAD ZINC PLANTCrushing PlantThe crushing plant described in the previous paper was located adjacent to the Urquhart shaft. The crushing plant had grown considerably over the years by the addition of a 4ft. BY-mons shorthead crusher and a set of Traylor 72 in. x 20 in. crushing rolls and, whilst operating satisfactorily, was difficult to maintain and cramped in many places. As a satisfactory layout for the new copper crushing plant could not be made in the vicinity of the, existing plant, it was decided to construct a new plant on the western side of theconcentrator building and provide identical equipment in...

Jan 1, 1953

The increasing introduction of high capacity mechanical equipment into the coal mines of New South Wales following. tforld War II brought with it problems of roof support. Rapidly advancing headings in difficult country could not be supported with heavy, close,timbering due to the time involved in installation and the reduction of available' space for the movement of machines. _ The installation of low cost, space saving, rapidly installed roof supports became a necessity if the new mechanical equipment wa-s to be allowed to operate at maximum efficiency. As, a result of experience in the United States of America, the system of roof support using steel reinforcing bolts began to find increasing, popularity in the mechanised mines in this State. From the somewhat'crude methods of in- stallation adopted in some of the, early trials, the practice of roof bolting has advanced into a-highly technical operation, requiring care and skill to ensure optimum results.

Jan 1, 1971

This paper discusses the use of tapered roller bearings in conveyor idlers. It shows that in medium and high capacity systems, tapered roller bearings can offer significant cost and performance advantages. In the next ten years, conventional conveyors will face increased competition from unconventional belt conveyors, pneumatic systems, pipeline "slurry" systems, unit trains and so on. The conveyor industry must meet these challenges by innova- tive use of technology. Conventional belt conveyors must continue to show the lowest cost per tonne-km or lose their position in the market. Tapered roller bearings can contribute to the achievement of this goal. The concurrent resources boom and liquid fuel crises may well see a decline in the use of heavy trucks for bulk material handling over moderate distances 10 to 50 km. There appears to be a trend in the conveyor industry to go to higher speeds with improved belting in conven- tional widths. The transmission of more material over a given period of time will place more demands on conveyor idler bearings. Australia has in general followed the European practice of using deep groove ball bearings in conveyor idlers.

Jan 1, 1978

The first mining in Western Australia probably commenced some 40 000 years ago when Aborigines arrived and began quarrying stone for tools and weapons, and ochre for decoration. The earliest documented mining by European settlers took place in 1850 on a small lead vein in the bed of the Murchison River, reported by the explorer A C Gregory. However, it was the discovery of gold in the Kimberley region in 1885 that first drew wider attention to the State's mineral potential.

Jan 1, 1992

The reasons for selecting two stage pebble milling in preference to conventional methods of grinding are discussed. Commissioning of the first section was completed in October, 1969. Improvements in both the operating and engineering aspects were then incorporated in the section commiss ioned in March, 1971.

Jan 1, 1975

By Robins R. G

The dissolution of metallic copper powder in aqueous solutions of cupric sulphate under the influence of ethylene gas was investigated. The dissolution reaction stoichiometry obtained was: Cue+(aq) + Cu(s) + 2C2H4(g) = 2(CuC2H4)+(aq) The rate of formation of the copper (I)-ethylene complex in the above reaction was studied in a laboratory autoclave and the effect pH, temperature, ethylene partial pressure and initial concentration on the dissolution rate was measured experimentally and expressed theoretically in terms of several simple conceptual kinetic models. The results led to the selection of optimum conditions for the reaction and the suggestion of an "ion-molecule reaction" mechanism to explain the very low activation energies for the reaction system. The area of application of this reaction lies in the direction of refining impure copper such as cement copper. Several experiments were performed in which an acidified solution of cupric sulphate under ethylene pressure was used to dissolve copper from the cement copper powder in the form of the copper (I)-ethylene complex, followed by the release of gas pressure to disproportionate the complex and precipitate a purer metallic copper.

Jan 1, 1987

By S MacKinnon, J Kok

Potential areas for improvement in flotation performance were identified during JKTech model development surveys in October 2003. Subsequent implementation of the JKTech recommendations in consultation with flotation cell manufacturer Outokumpu have resulted in gold flotation recovery increases of more than four per cent over a two-year period. One of these recommendations was the installation of High Shear Stators in the Cleaner and Recleaner flotation cells. The High Shear Stator installation project was justified based on simulations completed using JKSimFloat. Bubble size measurements completed before and after installation of High Shear Stators showed a reduction in mean bubble size of approximately 50 per cent in the Cleaner cells. Both Cleaner and Recleaner banks showed a significant narrowing of the bubble size distributions following the installation. Plant gold recovery increase resulting from the installation of High Shear Stators was 1.1 per cent, with a 1.9 per cent increase in flotation gold recovery and 5.4 per cent increase in flotation sulfur recovery. Based on the 1.1 per cent recovery increase and total project cost of less than $200 000, the High Shear Stator Project NPV was $8 200 000 with a 0.25 year payback period.

Jan 1, 2006