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Gold mine production in South America was 247.3 tonnes in 1995 up from 156.4 tonnes ten years earlier in 1986. This represents a 58 per cent increase and amounted to 11 per cent of total world gold mine production. The major countries involved in order of production, were: Brazil (67.4 tonnes), Peru (51.5 tonnes),. Chile (48.5 tonnes), Colombia (24.1 tonnes), Venezuela (17.1 tonnes), Bolivia (16.0 tonnes), Ecuador (9.6 tonnes), Guyana (8.8 tonnes), French Guiana (3.3 tonnes) and Argentina (one tonne). The most dramatic increase was reported in Peru where production increased from 10.9 tonnes in 1986 to 51.5 tonnes in 1995, heavily influenced by the production from Minera Yanacocha which began operations in 1993 and produced 17.2 tonnes in 1995.With the reformation of the mining laws and the introduction of investment incentives in all the South American countries in recent years, dozens of major and junior mining companies began flocking into the area in the early-1990s to conduct exploration. A recent study undertaken in Brazil shows that an average of $240 million per year will be expended in this country during the period 1993 - 2010. Twenty-five per cent of this expenditure is expected to be made on gold exploration. Similar figures for Peru are $220 million total per year with 50 per cent for gold; $170 million per year in Argentina with 25 per cent for gold and $120 million ner year in Chile also with 25 Der cent for gold.

Jan 1, 1997

Significance of Ion Interactions in Flotation in Saline and Brine Solutions

Sep 13, 2010

By B Vernon, M Whiteley, T Robinson

The Western Australian gold industry has approximately 100 operating plahts, mainly CIP/CIL. The nature of the State's rapidly expanding gold industry gave rise to concerns over management of the  cyanide hazard, in that most plants are remote from major population centres, have a workforce with a high tum over and use highly saline process water. Approximately 4500 workers in the industry have the potential to be exposed to cyanide in the course of their normal work.   This paper outlines the risk management strategy developed by Government and industry to monitor atmospheric HCN gas in the work environment and the role of continuing education and training along with regular site inspections by Department of Mines Inspectors.

Jan 1, 1990

There was a time, in the memory of some here tonight, when the annual meeting of The Institute was a nostalgic occasion. Often, in the 1920s, there was comment on the decline of Australian mining and on the lack of new mineral discoveries. When some of our Presidents prayed then for a new Bendigo, and instead were given a Mount Isa, they were justifiably disappointed because of the vastly different capital requirements.In 1967 the mining picture is very different. The recent mining developments in Australia are certainly as important as several Bendigos and several Kalgoorlies. The mining industry in Australia has never been more dynamic than today (Table 1). And if we ask why it is so dynamic, the answer lies in the role which overseas capital is playing in the industry. The contribution of overseas capital should concern us not only because we are members of the mining and metallurgical profession, but also because we have a duty to make our profession contribute as much as possible to the well-being of Australians. It is not sufficient to argue that overseas capital is good for the mining industry; we must also examine whether it is good for the economy and the nation. In this context the current criticism of the inflow of overseas capital into Australian mining is useful, for it gives us an opportunity to see what has resulted from the inflow.In discussing this question I do not suggest that we emulate Captain Hancock, that legendary Moonta mine manager who, according to Oswald Pryor's cartoon, used to say to his miners: "When I say a thing is, it is, even if it isn't". The question can only be discussed on a factual basis; and I would submit that many of the important facts relating to overseas capital in our mining industry are often overlooked or ignored. I would further submit, on the basis of these facts, that Australia's present day mining industry has been largely built on overseas capital and that the overall benefits of that capital to Australia have been enormous.

Jan 1, 1967

By M I. Pownceby, A Torpy, C Johnson, N C. Wilson

To extract uranium from low-grade, calcrete-hosted uranium (CHU) ore is challenging owing to the presence of carbonate and swelling clay gangue minerals that require an alkaline lixiviant to be used. Western Australia possesses ~75 000 U3O8 t in CHU resources. Improvements to alkaline leach extraction practices would improve the economic potential of these deposits.A column leach study of CHU ore was run for 105 days using an alkaline carbonate-bicarbonate lixiviant. The uranium content of the liquor plateaued after 75 days at ~275 mg U/L; the calculated maximum solution capacity was 800 mg U/L. Spiked peaks and troughs were seen in the data set beyond the 60th day, where concentrations ranged from 220 - 290 mg U/L, indicating possible cyclic uptake and loss of uranium from the solution.Pristine and leached ore samples were geochemically analysed and mineralogically characterised at high resolution using a field emission gun-electron probe micro-analyser (FEG-EPMA). Results showed that leached ore samples from the top of the column contained less carnotite than pristine ore. In contrast, leached ore samples from the column base contained regions with more carnotite than pristine ore, indicating precipitation. Three carnotite grain micro-structures were identified in the leached ore; fan-spherulite, granular and core-shell cubes, with evidence for multiple growth phases.Evidence of carnotite precipitation was seen at the edge of and in pore spaces within montmorillonite and dolomite grains. The point of zero charge of both minerals is lower than the pH of the lixiviant (pH 10.8), thus the mineral surfaces are negatively charged and would not attract UO2(CO3)34- ions out of solution. Similarly, the decrease in the uranium content of the lixiviant is not attributed to super-saturation, as this was unlikely to have been achieved. Work is ongoing to understand the reason for carnotite precipitation and the fluctuations in the lixiviant uranium concentration that are seen.CITATION:Johnson, C, Pownceby, M I, Wilson, N C and Torpy, A, 2013. Microscale characterisation of pristine and processed ore - implications for leaching calcrete-hosted uranium ore, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 303-316 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By BLAKE DAWSON WALDRON

I must acknowledge my strategic adviser, Mr Lance Grimstone, who contributed to the development of this paper, and collated the text and figures.

Jan 1, 1994

By R Kahnt, S Jahn, D Baacke, M Eckart

Relocation into the Lichtenberg open pit mine of about 110 million m3 of sulfide-bearing and ARD-generating waste rock piled up on the surface is the most important and cost-intensive single surface restoration project conducted by WISMUT GmbH at the former Ronneburg uranium mining site. The waste rock comprises for the most part Palaeozoic shales, limestones and diabases with pyrite contents of up to seven per cent. Waste pile relocation began in 1992 and is scheduled to be completed by 2007. The approach used for relocation has been extensively described elsewhere (Jakubick et al, 1997; Hockley et al, 1997; Chapman et al, 1998; Paul, 2003). Following completion of the backfill that will be up to 60 m above the initial ground level, a dry cover will be placed on top of the backfilled mine wastes. The area to be covered amounts to about 220 ha. Design planning for the final cover placement of which is to begin in 2004 had to be based on a comprehensive cost-benefit analysis over and above compliance with legal requirements. The crucial question to be answered in this respect was to determine û in addition to the expenditure required to ensure reuse, radiation protection and soil protection û the extent to which additional time, effort and money were justified in order to minimise contaminant release from the unsaturated portion of the backfilled pit contributing to total releases into the ground water and possibly achieve savings in long-term operating costs for the on-site water treatment plant. Optimisation was based on contaminant balance modelling for the entire site reproducing dominant physical and geochemical processes. Among the specifics underlying the cover design is that contaminant release from the backfilled open pit must not be considered independently of that from the adjacent flooded underground mine and that a major part of the backfilled open pit will also be submerged. Following weighing of cover-related short- and long-term costs it was found that higher construction costs for the various cover options will not be offset by cost savings in the long-term water treatment. As a consequence of pit flooding, even a costly multiple cover including an impermeable layer will only insignificantly impact on concentrations and loads at ground water spill over points. As a result of comprehensive studies and investigations, a combined cover of cohesive soil material from on-site excavation overlain by a 0.4 m thick storage layer to restore natural soil functions for revegetation was derived and submitted for approval. Together with hydraulic measures, this approach is to meet any requirement in terms of radiology, water protection, stability, erosion protection, and reuse.

Jan 1, 2003

Knelson concentrators are commonly used to recover fine liberated gold in gold processing plants. The decision to employ a gravity gold circuit consisting of centrifugal devices such as Knelsons is primarily taken on the results of GRG tests, among other considerations. While the GRG test is considered a material characterisation test, which is useful in the design stages, its use in evaluating the performance of an existing unit is questionable. The problem is exacerbated by the fact that it is time consuming and costly. This paper examines the validity of the GRG test for performance evaluation and discusses alternative test work that can be performed to evaluate the performance characteristics of an operating machine. Principles that are useful in selecting optimal operating parameters, such as optimal fluidising water flow rate for a given ore/machine combination, are also discussed and illustrated with laboratory and plant data.

Jan 1, 2007

By B S. S Rao, S Chandra

IndiaÆs iron ore mining industry is growing rapidly in order to augment the capacity to meet the unprecedented demand for the iron ore. Traditionally, much of Indian iron ore production came from exploitation of high-grade haematite ores, with the exception of Kudremukh which beneficiates lean grade Banded Magnetite Quartz ore. Now with the changed scenario of demand and supply, keeping long term sustainability in mind, it is imperative to develop suitable processing technology for exploitation of banded haematite quartz (BHQ) ore available abundantly and not utilised so far. In this direction detailed characterisation and beneficiation studies were conducted with BHQ iron ore from the Bellary-Hospet region of India, assaying 36.5 per cent Fe. The mineralogical studies with the image analyser system revealed the presence of maghemite and haematite as iron-bearing minerals. The gangue mineral associations were siliceous, ferro-magnesian and carbonate minerals. Higher degrees of liberation were observed in the size range of 75 - 212 microns. Liberation grind tests were performed by grinding the ore to different top sizes in a closed circuit laboratory ball mill with the ground samples subjected to Davis tube tests. The yield, grade and recovery were used as parameters to plan a two-stage wet drum magnetic separation based on grinding the primary magnetic concentrate. After subjecting the final magnetic concentrate to flotation to remove residual silica a concentrate assaying more than 68 per cent was obtained. The non-magnetic product from the primary magnetic separation was deslimed, ground, blended with secondary magnetic tails and was subjected to a two pass wet high intensity magnetic separation (WHIMS). The WHIMS concentrate was further subjected to two-stage flotation to remove residual silica to obtain concentrates assaying 64 - 66 per cent Fe. The final combined concentrate from wet drum magnet and WHIMS after flotation could yield a blast furnace (BF) grade pellet feed concentrate assaying more than 65 per cent Fe with a yield about 39 per cent and iron recovery about 70 per cent. A direct reduction (DR) grade pellet feed concentrate assaying 67 per cent Fe with a yield of about 28 - 31 per cent and iron recovery about 53 - 57 per cent could also be produced. Based on the test work, a process flow sheet was developed to beneficiate the BHQ ore for production of BF/DR grade pellet feed concentrate. In this paper methodology adopted for selection of individual process, various diagnostic tests performed to rule out other beneficiation processes and the final process flow sheet development is presented and discussed in detail.

Jan 1, 2007

By M Logsdon, T R. Clark, T I. Mudder

Oxidation of pyrite and other metal sulfides is accelerated by the activity of acidophilic iron- and sulfur-oxidising microorganisms. The ideal biocide for controlling biocatalysed acid rock drainage (ARD) would be inexpensive, inhibitory toward sulfide-oxidising bacteria at low concentrations, relatively non-toxic toward non-target organisms, degradable in the environment outside the zone of application, stable and long-lived in the impacted environment, sufficiently mobile to penetrate into piles of waste rock or tailings, and effective regardless of the metal sulfides present. A potent agent for combating ARD that fits these criteria is the thiocyanate anion (SCN-). The objective of this study was to determine the effectiveness of thiocyanate in controlling or preventing ARD within several types of sulfidic waste rock and tailings. Results were evaluated within a context encompassing process water and solids management strategies employed at different precious and base metal mines. Sulfidic rock was treated with solutions of potassium thiocyanate and subjected to accelerated weathering tests in lab-scale humidity cells, trays, and columns. Certain tests also utilised solid phase copper thiocyanate (CuSCN) to evaluate a ærelease on demandÆ strategy. Leach solutions were analysed for parameters indicative of ARD including pH, redox potential, conductivity, acidity, sulfate, iron, and certain heavy metals. Two larger scale field tests were also initiated by personnel at separate mines using, in the first case, ore containing a pyritic component in large columns and, in the second case, waste rock containing base metal sulfides in lined pits. Humidity cell tests showed low concentrations of thiocyanate solution applied to pyritic waste rock could reduce ARD formation by 90 per cent or more compared to untreated controls, with the residual release of ARD components (eg sulfate, Fe, acidity) probably reflective of strictly chemical oxidation of the sulfides by molecular oxygen. Thiocyanate applied at a concentration of 22 mg/kg to waste rock from a base metal mining operation in large laboratory scale columns reduced acidity and sulfate release by 75 per cent to 80 per cent compared to untreated controls. This extent of reduction in ARD may not meet discharge water quality criteria, but has the potential to significantly reduce lime consumption and sludge production in a conventional neutralisation facility. The use of a solid-phase metal thiocyanate compound (CuSCN) at a dosage of 194 mg/kg pyritic ore resulted in the following per cent reductions in leach solution parameters in comparison to controls: sulfate (78 per cent), acidity (93 per cent), dissolved Fe (99.4 per cent), and dissolved arsenic (99.9 per cent). This compound has the further advantage of being relatively stable until needed, dissolving only in the presence of an acidic and oxidising ARD solution. If this line of investigation progresses favorably, it offers the possibility of an ARD prevention technique that may be applicable in some settings. Mine-site pilot scale tests with pyritic ore resulted in reductions in sulfate (56 per cent) and Fe, As (66 - 68 per cent). In sum, thiocyanate at relatively low concentrations dramatically reduced ARD from sulfidic rock in a simulated heap. The pilot test using waste rock containing base metal sulfides has begun only recently. A preliminary process design and cost estimate was made for fullscale application of thiocyanate to waste rock at a hypothetical gold mining operation producing 5000 tpd of ore and 10 000 tpd of sulfide containing waste rock. The combined capital and operating costs for the full-scale thiocyanate application facility were about $US 0.25/tonne of waste rock and $US 0.50/tonne of ore. Although thiocyanate is readily available commercially, it also occurs in process solutions associated with certain types of mining processes. Such solutions after selective treatment might be recycled to sulfidic waste rock or tailings, rather than being treated for thiocyanate degradation.

Jan 1, 2003

By Dorricott M. G

Rock bolt installation is generally carried out in two steps. First the hole is drilled and the drill steel is extracted, then the bolt is inserted into the hole and tightened or grouted. With single pass bolting (SPB), however, these two steps can be carried out at the same time. This kind of bolting system has at least three advantages, (1) the time used for the bolt installation could be reduced, (2) the condition of safety for the operators could be improved, and (3) the degree of automation of the rock bolting practice could be increased. The study presented in this paper is concerned with the development of the SPB system. The current state of the system is discussed, and further improvement of the technique is explored.

Jan 1, 1992

Gwalia Consolidated Ltd has been in the mining industry for about 15 years, yet its key wholly owned Greenbushes Mine has a history dating back to the last century. Similarly Gwalia Consolidated's associate, Sons of Gwalia Ltd owns the historic Sons of Gwalia and Marvel Loch Mines with Sons of Gwalia celebrating its centenary this year. This durability is a testament to the quality of the orebodies concerned and the massive technological achievements over this time which have enabled each of these mines to maintain their competitiveness. While Sons of Gwalia and Marvel Loch were and continue to be gold mines, the wholly owned Greenbushes Mine has survived and in fact prospered through the development of alternative products from its rich and unique pegmatite. Similarly, for Gwalia Consolidated to grow and prosper it will be necessary to expand the current portfolio of products and operations. The Greenbushes Mine has already given Gwalia world `No 1' status in both the supply of primary tantalite concentrates and lithium minerals (spodumene). The asset base contributed by Gwalia's gold investments assisted in the recapitalisation of the Greenbushes assets to fully develop their potential. Industrial minerals and strategic metals were of interest to Gwalia as these markets are relatively small and it is possible to develop an influential if not dominant position in the market with a quality asset. Capital expenditure to develop such projects are also usually in the order of $10 m to $20 m, a manageable range relative to Gwalia's size.

Jan 1, 1996

In a modern economy there is a compelling case why governments should not own property rights to mineral deposits. Assuming they do, however, governments will use these constitutional rights to raise revenue. They have two basic instruments to achieve this; a royalty charge on price or a rent tax on income/profits. On the one hand, a royalty charge creates a 'deadweight loss' to society by increasing cut-off grades and decreasing the life-of-mine. They are also regressive. However, they are easy to administer. On the other hand, a rent tax avoids the problem of 'deadweight loss'; it does not impact on the life-of-mine because the tax structure is neutral. But, they are difficult to administer correctly, particularly in the determination of rents and the definition of mining per se. If rents are incorrectly determined capital markets are distorted. And, if mining activities are incorrectly defined, downstream activities could be adversely affected.

Jun 1, 2010

At the outset, I guess we should define what we mean by "com- modities". In the 20 minutes or so which I have for this paper, it is impossible to tackle all commodities -one would need to con- sider not only the base metals but also the ferrous iron and steel products as well as energy commodities such as coal, oil and even uranium. For the purpose of this address however, I would prefer to refer to the principal non-ferrous commodities: copper, lead, zinc, aluminium and nickel and, I would like to consider some of the changes which have taken place in the industry over the past 20 years-and the likely reasons for these changes. I would also like to dwell a little on the future and some of the key issues which-may influence the future path and direction of the metals industry.

Jan 1, 1988

Drilling is one of the most, significant cost components of any stoping or develop- ment operation. Two of the factors contri- buting to the drilling cost are the supply and servicing of consumable items such as drill rods and bits. The purchase cost of consumable items can be controlled to a large extent by using the correct balance of quality and price. However, the service cost is a less easily controlled factor and it is in this area where potential savings are significant. In June, 1976 a six month trial period was commenced at The Zinc Corporation, Limited and at New Broken Hill Consolidated Limited with two separate suppliers supplying and ser- vicing all longhole drilling parties (one supplier for each mine) at a guaranteed cost per metre. As a result of this six month trial period a new contract was commenced in December, 1976 with one supplier supplying and servicing all longhole drilling parties at both ZC and NBHC for a twelve month period. This concept has now been in operation for over twelve months and has proved to be a significant means of slowing down the increas- ing cost associated with drilling operations.

Jan 1, 1977

By E P. Leite, L A. Magalhpes

The Amazon Craton is one of the largest cratonic areas and comprises one of the est-endowed metallogenic provinces in the world. It hosts a number of different ore deposit types for which a variety of mineral exploration data are presently available at various scales and formats. These data, however, are not properly organised nor integrated by means of advanced spatial analysis tools. In this view, here we present a suite of neural network methods that were applied to these data, providing unprecedented mineral potential scenarios for several precious and base metals in the region. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

A Study on Main and Interaction Effects of Operating Variables of Column Flotation

Sep 13, 2010

This paper describes the operation involved in the sinking of a concrete-lined elliptical-shaped shaft at North Broken Hill Limited.Major factors such as geological features, future ventilation, ore haulage at depth and their relation to the location and selection of the type of shaft are described.Features covered in the sinking of the shaft include equipment details, with special reference to mechanical mucking, operational cycles based on time study analyses for sinking, concreting and the placing of steel sets. Safety precaution and statistical data is alsoincluded.INTRODUCTIONDue to the northerly pitch of the ore bodies in North Broken Hill Limited leases at approximately 42°, and the deepening of the active mining zone, it became apparent that No. 2 Shaft, the main operating shaft, would become unsuitable for the extraction of ore from the lower levels.Another major problem was the ventilation of the lower levels, and it was evident, that to ventilate efficiently these, and deeper levels, another upcast ventilation system would be required.Consideration was given therefore to the following: 1. Sink No. 2 Shaft from the existing bottom at 2770 ft. to 4200 ft., or Sink an internal shaft from the 2600 ft. level approximately 1000 ft. N. of No. 2 Shaft.2. Sink a new haulage and downcast shaft from the surface.3. Sink a new upcast ventilation shaft from the surface.It had been suspected that the ore bodies might flatten or even undergo a pitch reversal before reaching the...

Jan 1, 1956

Pipe Jacking has been a recognised method of tunnelling in the U.K. since the early 1950's, although I understand that pipes were pushed blind by the soldiers in the first World War from trenches on the Allied side to, or adjacent to, trenches on the German side, thus allowing explosives to be used with a certain element of surprise! 'However, on its more conventional to the U.K. in the 1950's, Pipe Jacking made considerable inroads into the tunnelling market place as an alternative to timber supported headings. This success was, unfortunately, fairly short lived because, owing to its simple method of operation, contractors paid insufficient detail to the engineering (or surveying) aspects and as such the system soon had a bad reputation for unreliability and lack of accuracy. Due to these failings, the market was not exploited and, therefore, there was a lack of investment by contractors, pipe manufacturers and also by any client, or research organisation, which is client associated. The effect of this meant that the system stagnated for a number of years and was used generally only for short crossing work (i.e. railways, canals and motorways), and then only in good homogeneous ground. Albeit, a limited number of full scale sewage disposal contracts were carried out, but with the lack of knowledge and experience of the clients, contractors and suppliers, (particularly the pipe suppliers), no reasonable success, either physical or financial, was achieved on any such contract.

Jan 1, 1987

By N C. White, C M. Allen, I H. Campbell

Porphyry Cu-Mo (Au) deposits of southern and western China are localised in ancient arc environments and continental-collision orogenic belts. Despite the contrasting tectonic setting, the known deposit geology and geochemistry appears identical in both. As such, the application of existing ore deposit models to atypical collisional settings suggests that significant potential exists for future discovery of significant porphyry deposits throughout the accreted cratonic blocks of Asia. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008