Search Documents

By M Darvall And R Fare, D Dormer

The Argo Archaean lode gold deposit is hosted within a structurally complex shear zone system, 70 km south of Kalgoorlie, and 3 km west of the crustal-scale Boulder û Lefroy Fault. Argo is an active underground mine currently producing at a rate of 120 koz pa with a Probable and Proven Reserve as at December 2005 of 2.19 Mt at 5.94 g/t Au (419 koz), a reduction on the December 2004 Probable and Proven Reserve of 4.58 Mt at 5.74 g/t Au (845 koz). This Reserve is hosted in six separate gold bearing lodes within the Argo shear system. Presently, a further six subeconomic shears are recognised. The 2005 Reserve figure represents a reduction of 426 koz compared to the 2004 Reserve as a result of a thorough review of the geological interpretation/resource model, and engineering factors applied to the Resource/Reserve, and depletion due to mining. Year on year Resource/Reserve figures at Argo had gradually increased as additional information on the system became available and mining methods were increasingly resolved with early production. The portal for Argo underground mine was cut in June 2002 within the highly profitable Argo open pit. The proposed æAvocaÆ bottom-up mining method required extensive lead time between development and the commencement of stoping in April 2004. During development considerable additional complexity in the Resource was encountered. Additional structures were identified, and complex splay interactions affecting the geology impacted on development. Intensive concurrent exploration in the footwall to the main lode during this period was the main cause of the increase in the Resource/Reserve figures during early development. As development progressed, lower grade continuity was observed than was previously interpreted. At the same time, drilling of deeper portions of the deposit and subsequent reinterpretation of the geological model significantly reduced strike lengths of economic mineralisation. Radical changes to the mining methods were required to improve productivities and to satisfy geotechnical considerations. The changes altered the engineering factors applied, which resulted in a reduction in the Reserve figures.

Jan 1, 2006

By J J. Plumb, P D. Franzmann

A study was conducted to describe the microbiology of the MICCL Monywa chalcocite heap bioleaching operation. Microorganisms were detected in the heap using culture-based techniques and cultureindependent PCR-DGGE analysis of the 16S rRNA gene. The metabolic requirements, temperature and pH optima were determined for selected strains isolated from the heap material. Six strains (BH1-BH6) were enriched and isolated from heap solids and leachate samples. Phylogenetic analysis of the 16S rRNA genes showed that strains BH3 and BH4 were closely related to the acidophilic bacterium Acidithiobacillus caldus and strains BH5 and BH6 were closely related to Leptospirillum ferriphilum. The optimum growth temperature for L. ferriphilum was 41.3¦C and the optimum pH range was 1.1 to 1.5. A new species of Archaea was isolated from the heap samples. Cells of the proposed species, Ferroplasma cyprexacervatum (æcyprusÆ L.n. meaning copper; æexacervoÆ L.v. meaning æto heap upÆ), are non-motile pleomorphic cocci, capable of chemomixotrophic growth with ferrous sulfate and yeast extract. Cells grow anaerobically on ferric iron in the presence of potassium tetrathionate and yeast extract as electron donors. Growth occurs from 14¦C to 63¦C, with an optimum temperature of 55.2¦C. The optimal pH for growth was 1.0 - 1.2. The species was phylogenetically most closely related to Ferroplasma acidiphilum with a 16S rRNA gene sequence similarity of 95 per cent. Molecular analysis of mine samples (16S rRNA PCR-DGGE) detected the above-mentioned cultured strains of microorganisms as well as species of Sulfobacillus and other unknown Proteobacteria. The microbial community of the Myanmar bioleach heaps contained similar levels of diversity to a dump bioleach operation in Chile, but contained greater amounts of biomass than another heap bioleach operation in Australia. The operating parameters of the Myanmar heaps (low pH and moderate temperature) have selected for the growth of moderately thermophilic microorganisms that are more commonly found in extremely low pH acidic mine drainage sites than in heap systems. The novel species of Ferroplasma is thought to be involved in the aerobic and anaerobic cycling of iron within the heap bioleaching environment.

Jan 1, 2004

It is indeed a pleasure to be here this morning to open the 4th Mill Operators' Conference. It is no mean feat to organise such an event and I would like to congratulate the committee for the work that they have done. I am sure that the Conference will be an outstanding success. I welcome overseas visitors and hope that they gain and share in the openness of this Conference. There is personal satisfaction for me to speak to you as a mining engineer addressing a large group of metallurgists and mill operators. I would have thought that it would be impossible for a mere mining engineer to inform a metallurgist of anything. I will desist from using such derogatory terms as "xanthate munchers", "bubble makers" and "glorified mathematicians". Terms of endearment as these may not be seen with much equanimity. Such is the warm association that the two professions have enjoyed over the years. The economic climate that we at present face is a major problem to all of us. I wonder how many people here come from mining operations that are in trouble financially or that are cutting back in one form or another. This is the recession that we needed to have. When the world's greatest treasurer can tell us that then we truly have a lot to fear. The present downturn can be seen as a normal adjustment in the cycle of our business. Yet the world does not experience such severe adjustments as frequently as we experience ours. The root cause for the regular adjustments can be placed at the feet of inflation. Until the politicians of this country of ours can come to grips with inflation, we will continue to experience downturns on a 5 to 7 year cycle. This, in my opinion, is the basic reason why we appear to experience more downturns than the rest of the world. We simply price ourselves out of the market. This takes about 5 to 7 years to be highlighted and then we need to make adjustments. However, this recession is worldwide. The adjustments usually take the form of redundancies, retrenchments and early retirements. What is the solution?

Jan 1, 1991

By Miyashita T, Yamamoto R, Kishimoto s

Following considerations of the effect of furnace size on pressure loss, pressure loss in front of tuyeres, gas flow in the lower parts of the furnace, the distribution of the burden and the gas flow in large blast furnaces is examined with particular reference to the burden distribution at the throat and the gas flow at high production rates. Improvement of gas flow is related to application of super-high top pressure and the use of moveable armour. A brief description of the NKK type moveable armour is given and its use in controlling the gas flow outlined. The operating results under controlled gas flow show an increase in production of Fukuyama No. 5 BF from 9,200 tpd to 11,000 tpd with a decrease in the fuel rate from 490 kg/thm to 460 kg/thm.

Jan 1, 1975

By D Fargher

BHP BillitonÆs Cannington operation began production in 1997 and is presently the largest tonnage and lowest cost single mine producer of both lead and silver in the world. The original design capacity was 1.5 Mtpa and this has progressively increased via a series of debottlenecking projects in both the mining and milling operations. In 2003, 2.39 Mt of ore was mined, whilst 2.31 Mt of ore was milled. In February 2003 Cannington received approval to expand the project to a sustainable capacity of 2.4 Mtpa. This resulted in underground development into the northern zone, upgrades to the concentrator, increased accommodation at site and power station capacity. The Cannington project development team implemented a partnership approach to the project. Fraser Osborn Engineering and Outokumpu Technology worked closely together with the Cannington team to meet all of the project constraints.

Jan 1, 2004

By Curless JM, Power SG

Polymetallic hydrothermal veins of the Western Cascades are hosted in propylitically altered Tertiary volcanics of calc-alkaline affinity and (or) in nearby, altered, and compositionally similar plutons. Ores from shallow and now abandoned mines produced mostly gold and were considered to be of epithermal origin. However, recent discovery of breccia and porphyry types of Cu-Mo mineralisation and other data suggest that the deposits of this terrane vary systematically both regionally, south to north, and locally, high to low altitudes. The evidence includes changes in (1) size, composition, and complexity of plutons, (2) types of mineral deposits; (3) assemblages of alteration and ore minerals; (4) trace metal geochemistry of host rocks; and (5) fluid inclusion and sulphur isotope data. They collectively imply a consanguineous origin of vein, breccia, and disseminated-veinlet types of mineralisation by magmatic hydrothermal processes.

Jan 1, 1987

In the future to excavate sufficient coal for power generation, two dredgers would be required to dig overburden or interseam 70010 of the time and three dredgers 40010 of the time. One overburden system was not adequate for this requirement, making coal production reliability vulnerable. TS5 spreader is the new machine element of this system. The selection of the best type of machine configuration to suit the application was then subject to an internal SECV VE Study, a registration of interest and a tender for two machine alternatives. This paper outlines the reasons why SECV planned the Secondary Overburden System and how the Krupp machine met these requirements. It also identifies the main design features of the machine and its constructability which will allow the machine to be operational by the end of May, 1990.

Jan 1, 1989

By Lewis J. W

The mineral sand orebodies of the east coast of Australia occupy approximately three per cent of the dune-heath-wetland coastal environment. They are associated with coastal plant communities ranging from Holocene high dunes carrying mature Eucalypt forests to low- lying heaths on Pleistocene deposits. Commonly, 0.25 to 1.5 per cent of the sand volume mined is removed from the site. Therefore, the volume change is insignificant. The equipment and techniques in use are flexible and the land can be returned in a manner suited to its subsequent use for grazing, subdivision or recreation. Landforms similar to the pre-existing are created in two case studies given. Sophisticated revegetation techniques are practised and are discussed in two case studies. Pre-mining vegetation surveys and post-mining monitoring are used to guide the management of the ecosystem.

Jan 1, 1976

By Armstrong A

Queensland is Australia's second largest mining state with world-class deposits of coal, base metals, bauxite and magnesite. The total value of Queensland's mining production is about $5 billion per annum, and coal accounts for around 55 per cent of that total. The environmental issues which arise as part of management and regulation of the industry are resolved within the EMOS process. The Environmental Management Overview Strategy is the cornerstone of the policy 'Environmental Management for Mining in Queensland' developed jointly by the Queensland Department of Minerals and Energy and the mining industry. The Gordonstone Coal Mine is the largest underground mine to gain approval under the new policy. Accordingly, Gordonstone has a well planned environmental management program which takes into account site-specific factors and provides for continuous compliance with the provisions of the Mineral Resources Act in a self-regulatory context.

Jan 1, 1994

By Heesteman LJL, Turvey DJ

The Mangani mine in West Sumatra is historically one of the most important precious metal mines in Indonesia, although the past production by World standards is small, totall- ing 5.66 tonnes gold and 242 tonnes silver. The geology is dominated by a distinctive NW-SE graben structure formed by dextral splay faults from the Sumatran Fault System. Quartz- rhodochrosite-rhodonite-Ag-Au veins are hosted by Tertiary pyroxene andesite volcanics and quartz-phyllite conglomerates, on N-S tensional fractures which intersect the Mangani graben. Intrusive rocks include andesitic dykes, pyroxene microdiorite, and hornblende granodiorite. Quartz-epidote-pyrrhotite alteration is related to concealed intrusions. Precious metal vein mineralization is characterized by: high Ag/Au ratio (>25); complex sulphide mineralogy of Fe, Mn, Ag, Cu, Pb, Zn, As, Se and the occurrence of Sn as stannite; low total sulphide content (

Jan 1, 1987

Australia has been a major exporter of LPG since production from the Bass Strait fields commenced in 1970. Export levels have been maintained through the seventies, the bulk of material being delivered to Japan. During this period the use of LPG in domestic markets grew only'slowly and demand was largely met by production from refineries with only shortfall supplies being drawn from naturally occurring sources. The domestic demand is forecast to grow significantly during the eighties as the traditional, automotive and petrochemical uses of LPG are expanded. An increasing amount of naturally occurring production will be directed into these markets. Despite this redirection the current level of exports (about 1.5 million tonnes per year) is likely to be maintained through much of the decade ahead as production from the Cooper Basin and the North West Shelf becomes available.

Jan 1, 1982

By Barber J

The manganese ore of Groote Eylandt is a shallow sedimentary deposit of Cretaceous age. There are a number of deposits which vary greatly in ore texture, density, percentage of matrix and thickness. The thickness in the present five operating quarries varies from 1-5 metres. The mine output in 1973 was 3 million tonnes of which 60% was blasted, the remainder ripped and bulldozed. The shallow deposit and its varying thickness create rather unique blasting problems which must be overcome in order to produce a minimum overall mining cost but not necessarily resulting in a minimum drilling and blasting cost per tonne. Future planning envisages the introduction of site mixed slurry explosives following test work and the application of a twin boom single operator rotary percussion drill. The paper outlines the overall developments,present and envisaged practices and the reasons for these changes.

Jan 1, 1974

By Ueki S

Underground coal gasification (UCG) is a promising process for obtai- ning energy from coal, which is either unmineable with current mining techno- logy or uneconomic to recover, using conventional methods, in the present energy market situation. There are several coal fields, which could become new coal reserves, if the UCG process were successfully applied. In the 1960's Japanese researchers made a number of basic studies and field tests into UCG, although not all of them produced favourable results. This paper reviews Japanese research on UCG. This includs basic studies into coal gasification using a small, tube reactor fed by air and oxygen, and also large scale model stu- dies(reactor size of 8.Om x 2.4m x 1.5 m). Field test results from Akabira colliery in Hokkaido and a feasibility study of power generation using UCG from a coal field in Hokkaido are also Presented.

Jan 1, 1987

The City of KalgoorlieBoulder is situated approximately 600 kilometres to the east of Perth, and as the major regional centre of the Eastern Goldfields, supporting a population of approximately 25 000. The formation of Kalgoorlie Consolidated Gold Mines in 1989 brought the existing operating entities adjacent to the city under common ownership and management. The Joint Venturers forming the management company are Homestake Gold of Australia and Gold Mines of Kalgoorlie (a Normandy/Poseidon company).This traditional underground mining centre has been worked since 1893, yielding 40.5 million ounces of gold ore with an average head grade of TEN grams per tonne. Historically the heart of the operation has been the famous Golden We located on the Eastern perimeter of the city, in the area known as Fimiston. The other significant operations that form KCGM are the Mt Percy Open Pit and the Mt Charlotte Underground Operation.

Jan 1, 1992

Chlorine as a lixiviant for gold possesses a number of significant chemical and Idnetic advantages over cyanide but because of its corrosive and vaporous nature the method of implementation needs to be significantly modified. At comparable reagent concentrations the dissolution rate for gold in the C12/Cl- systems is some 10 - 100 times that achieved in the 02/CN system. The dissolution rate in the chlorine system is largely a function of the concentration of C12, Cl- and pH. Under conditions of low Cl', (less than 50 g/1), the dissolution rate begins to drop off dramatically over the pH range from 3 - 4. Increasing the level of dissolved chloride ions shifts the pH of this rate reduction to around pH 5 at 100 g/l NaCl, and to around pH 6 at 300 g/l NaCl.

Jan 1, 1991

By Daoust G, Dubois JF

The optimal sequence of decisions on rates of production and cutoff grades is obtained by a dynamic programming model. The main parameters are : 1. the size of the deposit, average grades and grade distributions, 2. the operating costs of mining and concentration, 3. the investments in mine and mill, 4. the smelter charge, 5. the price(s) of the metal, 6. the recovery and the grade of the concentrate, 7. the rate of interest, 8. the taxation formulae, 9. the upper limit to rate and the rate interval and 10. the upper and lower limits to cutoff and the cutoff interval. An amount of ore can be mined at various rates while applying various cutoff grades. It is assumed that a decision to mine at a certain rate during a period conducts to a certain state regardless of the cutoff grade. This assumption which is valid for several

Jan 1, 1977

By White A, Price G

The main assets of a mining company are its orebodies; the second are the people who find and use them.The graphs in Figure 1 were derived from a paper by Rob Macdonald of Rothschild Australia presented to The AusIMM Centenary Conference in Adelaide earlier this year. They show that the value of the industry on the Australian Stock Exchange halved over the past decade, despite the re-investment of capital equivalent to its full market capitalisation. Why is this so? The average dividend yields for the ASX Mining Index was never above five per cent during that period and barely averaged 2.5 per cent. Why then is $Ai million capital re-investment per employee since 1960 not enough to generate a rate of return to investors better than lousy bank interest? Do the investing public no longer regard our industry's assets to be world class?

Jan 1, 1993

By Scott B. R

Bougainville's copper mine is located on the west slope of the Crown Prince Range on Bougainville. A high grade copper concentrate is produced for sale to overseas customers. Production planning which was originally based on pilot plant data has developed progressively since commissioning of the concentrator in 1972. Pilot plant data and mine sampling have been supplanted by the correlation of concentrator performance with ore sources, as the basis for short term planning. The influence of accurate sampling is reflected in 1. hourly shift control, 2. the daily milling statement, 3. the prediction of the characteristics of ore from various mine locations, 4. production reconciliation, and 5. the control of copper losses. The mechanical and electrical failures of the original sampling system emphasized the need for a reliable, automatic sampling facility. The development of a pneumatic drive mechanism, which has now been fully field tested, was undertaken.

Jan 1, 1976

By Ellyett C. D

This paper is an appraisal of the application of optical-mechanical-scanners operating in the non-photographic infrared wavelengths (3-5 and 8-14 micrometres) to mineral exploration in Australia. Pundamental principles of the operation of airborne scanners and their data output, thermal infrared (IR) imagery, are summarized. It is contended that thermal IR imagery often depicts the distribution of electromagnetic radiation emitted from earth surface materials better than aerial photographic techniques because optical-mechanical-scanners sample wavebands which straddle the wavelength peak of earth surface emission. To illustrate the geological features which such scanners can depict, reference is made to thermal IR imagery of a number of areas in Australia where the technique has been applied for exploration purposes. The images demonstrate that this technique can detect structural features like faults and folds, stratigraphic data by distinguishing different rock types and delineating their

Jan 1, 1973

By Ryan CG, Both RA, Mernagh TP, Large RR, Hunns SR, Gemmell JB

The Hellyer and Mt. Chalmers deposits are mound-style volcanic-hosted massive sulphide (VHMS) deposits in Australia. Textural, petrographic and microthermometric investigations of fluid inclusions in the Hellyer stringer system indicate that Type I, primary, liquid-vapour inclusions are 10-15 pm in size, and yield homogenisation temperatures of 170-220¦C in early 2A veins, 165-322¦C in main-stage 2B veins and 190-256¦C in late-stage 2C veins. These data suggest a waxing and waning thermal history. However, the average salinity remained between 8-11 NaCl equiv. wt % in all Stage 2 veins. At Mt. Chalmers, Type I inclusions up to 20 ¦m are found in quartz from the mineralised zone, and these inclusions yielded homogenisation temperatures of 160-268¦C and salinities of 5-8 NaCl equiv. wt %. Laser Raman spectroscopic (LRS) analysis indicates the presence of CO2 (

Jan 1, 1995