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The investigations of the Leningrad ruining lilstitute on this problem are carrying out in the following main directions: 1) The analysis and study of contaminants migration at particular sites of mining development; 2) The working out of theoretical and me- thodical basic principles of aquifers migration tests; 3) The work- ing out of methods of the forcasting of groundwater pollution pro- cesses; 4) The theoretical and uethodical substantiation of hydro- geological observations of groundwater pollution processes; 5) The wort ing out of the measures at the groundwater control and their rational use at the particular sites of mining development. The research that have been carried out by the present moment have covered the wide range of wining and geological conditions -- as from the point of view of specific genetic types of water-be- aring rocks (porous, fissured and fissured-porous), as well as from the point of view of pollution sources (surface waste water basins and underground basins of non-standard water) and the cha- racter of the latter's migration (tracers, physically neutral ef- fluents, heavy or light ones). The combination of specialized mi- gration tests and observations carryed out at uoayi, sites, as well as the following ar~,alysis o:i the data of field study allowed to get useful theoretical, methodical and practical results on the all directions above mentioned, ns the summing up of these results the author proposed the concept of controlled ground :ester polluti on. This conception is based on three whales" - groundwater self- purification, engineering prevention measures and ground-water monitoring correlated with each other by succes i.vely refined (ac- cording to the observation data) hydrogeologicZl forecasts.

Jan 1, 1988

By Carter D

The Chairman of this afternoon's session is Dick Carter. This afternoon is the culmination of this conference. We've looked in the first session at regulation; in the second session at valuation techniques and this session we look at valuation in practice. Dick's involvement in the mineral industry has been wide ranging and distinguished. Dick has worked with BHP since 1960, when he joined BHP Steel as a commercial trainee. Dick holds a B.Comm. from the Newcastle University College of the University of New South Wales and was educated at the Australian Administrative Staff College and Harvard Business School Advanced Management Programme. During the past decade, he has headed the minerals group's Aluminium Divison, Resource Planning and Development, Non-Ferrous Metals and Business Development Organisations. Dick currently serves as Executive Director of BHP Gold Mines Limited and Managing Director of Ok Tedi Mining Limited. His experience covers Australian Manganese Company, Mineral Deposits Limited, Northern Rivers Rutile, Tasmanian Electrometallurgical Company Limited, Mount Newman Joint Venture, Worsley Aluminium and Carnilya Hill Joint Venture Operating Committee. His industry associations include the Executive Board of the Gold Producers Association, the Federal Executive of the Australian Goldmining Industry Council as well as the World Gold Council. Ladies and gentlemen, Dick Carter.

Jan 1, 1989

Those involved in managing risk today are asking various questions: why is it so frustrating to discuss æriskÆ with communities? why do consultative processes around æriskÆ get more and more complex? where is all this going to end? These questions will be addressed by examining how our understanding of risk has changed from one based on biophysical hazard to a broader view that includes social and cultural factors. There is evidence to suggest that we are living in a ærisk societyÆ, where the goal of æsafetyÆ has replaced that of equality in a class based society. The global mining industry operates within this complex and politicised environment. The very meaning of ædevelopmentÆ has broadened from the narrow economic vision to include the social and environmental factors which make up æSustainable DevelopmentÆ. Corporate accountability now extends beyond traditional shareholders to wide groups of stakeholders. The mining industry is developing responses which look beyond traditional technocratic methods. At the industry level these responses have included the recent Mining Minerals and Sustainable Development global and regional reports It has proven challenging and difficult to operationalise these new understandings at the company level and it is time to look at the bigger picture.

Jan 1, 2003

A process was developed based on the thermal hydrolysis and precipitation of iron from solutions resulting from the leaching of zinc plant residue. A study was made of the hydrolysis of iron, at temperatures in the range 140-220°C, in both pure solutions of ferrie sulphate and in leach solutions derived from plant spent electrolyte.At 200°C hydrolysis of pure ferric sulphate solutions results in the precipitation of ferric oxide, Fe2O3, at low acid. concentrations, and a basic salt, Fe2O3.2S03.H20, at hIgher acid concentrations. At 180°C ferric oxide is precipitated at low acid concentrations, but at higher acidities. carphosiderite, 3Fe203.4SO.3.9H20, is the stable phase. Frequently a mIxture of ferric oxide and carphosldente IS produced at 180°C, the ratio of phases being dependent on the non-equilibrium experimental conditions.With solutions derived from plant spent electrolyte hydrolysIS at elevated temperatures results in the precipitation of jarosite compounds of the type NaFe3(S04)2(OH)6 The precipitation of natrojarosite jarosite, and ammonio-jarosite was studied in detail. Temperature, free acidity, and the concentration of sodium potassium, and ammonium ions are critical factors which affect the extent of precipitation.A process based on ammonio-jarosite precipitation was tested in a pilot plant.An alternative method of iron removal based on the addition of zinc oxide calcine, to neutralize excess acidity, and the precipitation of ferric oxide was also tested in the pilot plant. Both processes appear economically favourable...

Jan 1, 1967

By Hu Y, Li D, Qu G

In this paper the structural mechanism of the gold - lixiviant complex is investigated. The results show that there are two common characteristics in the outer orbitals for all the gold lixiviants: a) a (Y -type of HOEO to form the L-*Au co-ordination bond, and b) a it type f LUEOs, with symmetry the same as that of 5d orbitals of Au, to form L

Jan 1, 1993

The appraisal of mineral reserves by a lender is carried out at the initial stages in developing a loan for a mine. The depth of investigations is influenced by the competence of the explorer, the type of commodity and knowledge of the geological environment. The lender looks for a reserve life which exceeds the term of the loan plus contingencies for events such as cost over-runs, adverse markets and production difficulties. The physical features of importance are discussed. Factors with direct financial implications are considered for their incorp- oration in sensitivity analyses to allow risk appraisal. When satisfied, the lender can then proceed to review cash flow forecasts, the basic strength of the project, then determine with the borrower the components and alternat- ives of a loan package.

Jan 1, 1979

By G R Ryan

Dissatisfied with conventional wet processing methods for alluvial deposits, Resource Trend Pty Ltd of Cairns set out to develop a better process. After comprehensive investigation of existing dry techniques the principals have now developed a rotary dry concentrator that can handle the fine-grained fraction of alluvial deposits as well as the coarse. Four of these units have been mounted on an integrated towable treatment plant which has been in successful commercial operation for four years in northern Queensland. A second plant is now under construction for use in the United States. Grades of less than 0.2 g/lcm have been profitably mined at throughputs of about 80 cubic metres per hour and 85 per cent availability. The operation runs round the clock with an establishment of four. Major benefits, apart from lower capital and operating costs, are environmental. Ore is picked up, treated, and replaced in its original mixed condition within 25 m of its initial location. Rehabilitation is completed almost immediately behind the plant as it advances, leaving no slimes dams, coarse stockpiles, or haul roads. In 1993 the company won a Premier's Award for Environmental Excellence in the Queensland Mining Industry. The principal disadvantage is moisture, and the company is now actively seeking deposits in the deserts of the world. In Queensland mining is normally possible only for six months of the year.

Jan 1, 1994

Extensive geophysical exploration and drilling operations have been: conducted in, South Central Queensland by Phillips Petroleum Company and Sunray DX Oil Company since late 1959. The main outlines of subsurface geology are now known, but many problems must be solved before a comprehen sine. picture can be presented of the geology and petroleum prospects e Interpretations to date suggest that -fiddle Paleozoic sedimentary rocks, probably, related to the Tasman belt of geosynclines, once extended. over. most. of the area An oro;eny 2.n late Paleozoic time, succeeded by deep pre-Pexmian erosion, removed the older sediments over large. areas, but Paleozoic sediments, were preserved from erosion in the Adavale and ancillary structur-a.l basins. Marine sediments of Devonian age are con-sidered prospective source beds for petroleum. Current work is directed toward finding favorable structure and reservoir beds to test the oil prospects of the area.

Jan 1, 1962

Bulk mining and handling technologies have been affected in two ways by the soaring costs of oil products in recent years. Firstly, the substition of oil by coal, oil sands and oil shale demands the development of high-capacity mining and handling equipment, and secondly the rising fuel costs favour a trend away from cost-intensive heavy truck transport. To cope with the growing volumes of material in mining and handling, larger equip- ment units have to be designed. This tendency becomes apparent from the examples of the Hambach open pit mine in Germany, and the Port Kembla handling plant in Australia. A combination of the flexibility of heavy truck transport and the cost advantages of belt conveyors is achieved by the system of semi-mobile crushing installations described in this paper.

Jan 1, 1981

By G D. Price

The Golden Blocks Goldfield is located in the Slaty Creek area,North West Nelson, about 20 km west of Collingwood. Alluvial gold was discovered in Slaty Creek in 1861. Gold was mined from quartz veins up to 1.5 m thick at nine mines from the 1890s until the closure of the Aorangi Mine in 1911. Total production from the Golden Blocks Goldfield is estimated at 46 000 ounces of gold. The Aorangi Mine was the largest mine, with a recorded production of 27 978 ounces of gold at an average grade of 36 g/t. Quartz veins containing gold and sparse sulphide mineralisation occur in a slightly metamorphosed, complexly deformed over-turned sequence of Lower Ordovician sandstones and shales. Primary gold mineralisation is associated with intensely deformed zones that occur near or at carbonaceous shale and sandstone contacts. Some eighty-five percent of all gold production (39 000 ounces) came from four mines confined to the stratigraphically lowest, most widespread shale unit. The quartz veins exhibit textures consistent with a hydraulic fracturing mode of vein formation with fissure infill vein types predominating over replacement textures. Stylolites of carbonaceous material and recrystallization features within the veins suggest multiple phases of deformation. The lack of wall rock alteration, and low primary fluid inclusion temperatures of 200¦ - 265¦ indicate that the ore fluids were associated with a low temperature epithermal system. A model consistent with similar mineralisation styles observed in Ordovician sediments from Pacific Rim occurrences is presented. The high grades (up to 100 g/t) mined from the upper levels of several mines suggests supergene enrichment processes associated with the Upper Cretaceous weathering surface. The Golden Blocks Goldfield has had no modern exploration. The most recent exploration was undertaken in the early 1980s. There are known acid intrusives in the area, with potential for the application of new models of intrusive-related gold mineralisation.

Jan 1, 2004

Over the last 20 years the mining industry has played a key role in the further development of many Central Queensland and New South Wales communities. The number of people who are employed by the coal mining industry, the number of transient residents, shift work and the town facilities have all contributed to how the community views the coal mining industry. As the coal mining boom continues and the mining communities continue to grow more emphasis is needed to address the community concerns, specifically the socio-economic and environmental impacts that the coal mining companies may have on these communities. Central Queensland coal mining operations are situated in the Bowen Basin. Many of the towns in the region have been developed specifically for the coal mining industry with 13 - 50 per cent (Australian Bureau of Statistics, 2006) of people living in the communities being directly employed by the mines. The introduction of shift work, differing rosters and the mining boom have resulted in considerable changes to these communities with more transient contractors and permanent employees taking up residence outside of these communities. This change, however, has not been as noticeable in the Hunter Valley region. The Hunter Valley, situated in the Sydney Basin has two main mining towns, Singleton and Muswellbrook. Of the 37 173 (Australian Bureau of Statistics, 2006) people that reside in the communities 13.8 to 16.5 per cent (Australian Bureau of Statistics, 2006) are employed directly by the mines. The Hunter Valley is a large tourist destination due to its many vineyards; this results in a diverse community where mining is not the sole means of employment. Similar to Central Queensland the mining boom has brought more people to the Hunter Valley region, although greater percentages have taken up residence in the communities. The views vary between the two regions on the coal mining industry, specifically on the socio-economic and environmental impacts that the industry may have on the surrounding communities.

Jan 1, 2008

By J Player

Big Bell Mine started experiencing relatively large mining related seismic events, and accompanying rockbursts, from February 1999. Twelve rockbursts damaged access development from February 1999 to June 2000, with severe damage extending for up to 100 m along footwall drives. Five seismic events associated with the rockbursts were recorded by the AGSO, measuring 1.9, 2.2, 1.7, 2.4 and 2.2 on the Richter scale. These events affected 485 and 460 footwall drives in August and November 1999 and 535 footwall drive in June 2000 (drive level nomenclature is equivalent to the depth below surface and RL). After the third event (July 1999) it was apparent that the seismicity was not a once-off phenomenon. This (sudden) onset of seismicity required management to implement a series of precautionary measures:to ensure the safety of the workforce, to maintain continuity of production, and to reduce rockburst damage rehabilitation. The measures included extended re-entry periods and exclusion zones in high-risk areas, improved rockburst resistant support systems in areas prone to damaging seismic activity and improved support systems in areas prone to shakedown damage. A full-scale minewide ISS seismic system was ordered in October 1999 and commissioned in February 2000. A portable eight-channel CSIR-Miningtek system was installed at short notice as an interim measure in August 1999. This CSIR system covered the northern producing stopes, where the majority of the rockbursts had occurred. The objective of the seismic monitoring was to monitor relative activity and to determine trends with regards to time and location. MAP3D numerical modelling was used to investigate the relationship between seismicity and various combinations of stress components to assess the relative seismic risk in both current and proposed working areas. This information is used to determine where and at what stage in the mining cycle the rockburst resistant support is required. Analysis of the seismicity has determined two distinct modes of seismicity û small-scale localised, high frequency events in high stress areas and larger events related to shear along previously intact foliation surfaces. This paper includes a summary of the seismic history, seismic data analysis, support system design, mine design adjustments and management action to minimise the effects of seismic activity at Big Bell Mine.

Jan 1, 2000

The Ranger Project Area covers 78.6sq km and is approximately six km east-west by 14km north-south (Fig. 1). The area is known to con- tain two uranium orebodies, Ranger No. 1 and No. 3, two uranium occurrences, Anomalies 4 and 5 and three significant radon anomalies, Ranger 18, 19 and 48. The Ranger No. 1 and No. 3 Orebodies con- tain approximately 120 000 tonnes of U308 in highly chloritised metasediments of the Lower Proterozoic Cahill Formation. The orebodies occur as suboutcrop and exhibit significant radiometric anomalies. These occur within approximately 400m vertically of the projected unconformity with the sandstone of the Middle Proterozoic Kombolgie Formation. Oxidised and reduced uranium minerals occur in quartz-rich schists containing variable muscovite, chlorite and sericite and in the chloritic matrix of chert breccia. Secondary uranium minerals namely saleeite, metatorbernite and gummite associated with earthy iron oxides occur from the surface to 50m depth in No. 1 Orebody and up to 80m depth in No. 3 Orebody. Below the oxidised zone, uranium occurs as pitchblende finely disseminated throughout sequences of quartz muscovite chlorite schist up to 150m thick and as open space fillings in zones of structural deformation. The uranium-bearing schists directly overlie up to 300m of dolomite and magnesite containing minor interbedded schist units and are themselves overlain by approximately 2 000m of more micaceous schists of the upper part of the Cahill Formation. Regional metamorphism has occurred to at least amphibolite facies and has been followed by retrograde metamorphism to a greenschist facies equivalent. The metasediments are intruded by granitic pegmatites and dolerites. Uranium is associated strongly with chlorite of which there are at least five textural varieties. Not all of the various generations of chlorite have associated uranium. Graphitic schist horizons occur which are often less than one metre thick and discontinuous. These are best developed at the base of the quartz chlorite schist sequence where uranium grades up to 1 000ppm U may extend for several hundred metres beyond the main ore zone. Uran- ium is not common in the carbonate sequences and only occurs in chlorite segregations in disrupted zones. The unoxidised ore contains sulphides, mostly pyrite, which are low in abundance (

Jan 1, 1984

Mines in the future deliver a paradigm shift in the way mining, material handling and processing are performed, unlocking significant value through production efficiency, flexibility and lower costs and enabling substantial safety and environmental benefits (V Schweikart). Mines in the future are highly productive, with low production costs and are significantly safer. They operate with a skeleton crew and use intelligent systems that fuse information from field instrumentation and other sources to generate the most efficient operating environment. Automated systems are seamlessly integrated across the mine and across the corporate enterprise. Geological models, long-term and short-term plans create optimised production schedules, suitably generated by the mine simulator. Production schedules are shared with the operations management system for deployment mainly by remotely operated and autonomous equipment. As the schedule is implemented, information is collected and shared with various plans, schedules, models and optimisation programs. This production environment is managed in real time from a æCentral Operations CentreÆ and it is visible across the business providing fast and accurate information about productivity, machine condition and environmental conditions. Central Operations Centres also house teams of subject matter experts that monitor and manage the mines and are able to communicate directly with the skeleton crew in the field. Constraints across the production line are displayed and managed appropriately from this location to maximise throughput. Maintenance is interactive and predictive. Reliability specialists in Central Operations Centres monitor the status of machinery and equipment and adjust maintenance plans and strategies to suit. Mining businesses rely heavily on knowledge workers û people with considerable knowledge and learning û and by manual workers. This new knowledge workforce is a team of associates rather than of bosses and subordinates. Field experts become leaders with tremendous autonomy regarding their work. The former line hierarchy becomes a support structure, intervening only in extreme emergencies; instead of giving orders, they are now removing barriers, expediting resources, conducting studies and acting as consultants.

Jan 1, 2009

Lafayette Mining Limited, a listed Australian company, is developing a polymetallic Project on the island of Rapu Rapu, located to the east of southern Luzon in the Philippines. The Rapu Rapu Project is based on the Ungay deposit, which has proven and probable reserves of 6.0 million tonnes of 2.5 g/t Au, 28 g/t Ag, 1.2 per cent Cu and 2.1 per cent Zn. The Project will produce copper and zinc concentrates from a sulphide flotation plant as well as dore from a CIL gold plant. Average annual metal production over the projected six-year mine life is 9800 tonnes of copper, 14 000 tonnes of zinc, 50 000 ounces of gold and 590 000 ounces of silver. Despite a rich mineral endowment and long mining history, there have not been any significant new mine developments in the Philippines since the early-1990s. The investment climate has been affected by legal challenges to the 1995 mining code, civil unrest in parts of the country, the impeachment of the previous President and community concerns about the industryÆs environmental performance. As a consequence, the Rapu Rapu Project is viewed as a test case û within both the country and the international mining industry û on whether minerals investment in the Philippines is an acceptable business proposition from a risk perspective. Lafayette has faced formidable challenges in managing the development risks of the Project. The major risk areas of the Project for which the company developed strategies include: regulatory, environmental and approvals issues, technical evaluation, project development, social and community issues, land acquisition, and financial and marketing issues. This paper describes the risk management strategies successfully pursued by the company, and which have the Project on track to commence construction in 2003. Dealing with each of the areas in turn, Lafayette sought to develop strategies which either effectively neutralised, minimised or otherwise addressed the key risks most likely to be experienced.

Jan 1, 2003

This paper traces briefly the reasoning which led to the decision to extend the existing internal shaft at the Rosebery Mine and to instal underground a larger winder (No. 2 Hoist) with capacity to handle all hoisting requirements to a depth of approximately 2,500 ft. on an incline varying from 83" to 55" to the horizontal. It then covers the specifications and selection of the winder, the design of the winch chamber, rope raise and bins, the excavation, support and lining of the chambers and the transport to site and installation of the machinery. Finally a brief description is given of the mechanical and electrical parts of the winder.INTRODUCTIONThe existing shaft winder on the internal inclined shaft situated on No. 8 Level of the Rosebery Mine had reached the limit of its capacity. Hoisting 21-ton capacity skips in balance, with a 13/16-in. diameter rope, it required four layers of rope on the 3 ft. 6 in.drums to reach the loading station under No. 12 level at a depth of 864 ft. (Fig. 1). This entailed heavy wear on the multi-layered rope and heavy stresses on the cheeks of the drums. Continuous working on three shifts was necessary to handle ore, men and materials, and a hold-up from any cause whatever meant an interruption to production on the lower levels of the mine. The maximum output of the hoist whilst hoisting from the No. 12 level loading station was 50 tons per hour. It was obvious therefore, that a larger winder was required if output was to be maintained.Diamond drilling had proved the existence of sufficient ore at depths well below No. 12 to warrant exploitation and a decision had to be reached on the means of hoisting this ore.

Jan 1, 1958

By Lawrence M. J

It must be stressed that the following comments are offered only to assist mineral industry professionals in understanding the issues involved in personal liability. The information and views expressed herein are not intended to be a comprehensive guide or definitive statement of the law and they should not be regarded as a substitute for specific advice for individual situations. Readers should consult their own legal and other professional advisers before applying the content of this paper to their own particular circumstances. It is hardly news that work in the mining industry is governed by a complex regulatory and legal system which is constantly changing, but few realise just how directly they can be affected and become personally liable for any breaches. These may result in civil or criminal proceedings and personal assets are at risk. Owners, company directors, managers and now employees are at risk, together with consultants, contractors and suppliers of equipment or consumables, as well as government inspectors. They are liable for their personal decisions to act (or failure to act) in managing operations or carrying out directions, as well as for the actions of others under their control. This paper identifies the areas where such individuals in the open pit mining industry in Australia face the risk of personal liability and measures which can be used to minimise the risk or which can be used to make out a defence to legal action which could arise. There have always been a myriad of Commonwealth, State and Local Government laws and regulations with which to comply, and now international protocols are being used as a basis to impose greater obligations on all people. Once, the `corporate veil' gave some protection to the individual, but today there is negligible protection from the full force of the law. Not only are there various types of law enforcement officers, but public interest groups, shareholders, customers, suppliers, creditors etc may litigate. This paper is not intended to be an exhaustive discussion of the provisions of all the legislation or case law where individuals can be held) personally liable. These areas would include environmental, pollution and heritage law (including Aboriginal sacred sites); occupational health and safety (including workers' compensation) law; trade practices and fair trading law; contract law; corporations law (including the requirements of the Australian Stock Exchange [ASX] and Australian Securities Commission [ASC]); industrial relations law; anti-discrimination and sexual harassment law; taxation (including superannuation trustee) law; and the Common Law. The focus is on the following areas of regulation, which are outside the usual experience of those in the open pit mining industry (the Mining Acts and Regulations are specifically not dealt with here): ò Environment Law; ò Trade Practices Law; ò Occupational Health and Safety Law; and ò Corporations Law.

Jan 1, 1994

Detailed mapping in the Permian-Triassic clastic sediments of the Southern Alps delineates a number of strike-slip faults, both dextral and sinistral, associated with the major Alpine Fault to the west and displacing a tight array of fault blocks. Concurrent steeply plunging folds are deforming early major folds of probable Cretaceous age, and generating schist locally. To the east a major collapse zone has developed along the crest of a Cretaceous anticline, located over an ancient Permian submarine scarp, with a number of small normal faults. Further east, extensive Carboniferous to Triassic rocks of much the same appearance are exposed as horsts and grabens in a large possible extension zone through central and east Canterbury. This may have crept incrementally from Cretaceous from the offshore Bounty Trough to reach the eastern margins of the Southern Alps in the Pleistocene.

Jan 1, 1990

Reconnaissance geochemical exploration in the vicinity of low angle detachment faults which bound the core of the Paparoa metamorphic core complex yielded Au up to 14 ppm, with 35% of greywacke, granitoid and quartz vein samples in the northern range exceeding the 0.01 ppm detection limit. Au is associated with Ag, As, Sb and Cu anomalies consistent with epithermal-type mineralisation. The Ag and Cu anomalies also distinguish this mineralisation from older, mesothermal Au deposits widespread in the Ordovician 'slate belt' greywackes, which comprise much of the upper plate of the core complex. Baryte, molybdenite, fluorite and stratiform U mineralisation in the northern Paparoa Range may also be related to hydrothermal activity along the detachment fault zones.

Jan 1, 1995

By V P. Beskrovnaya

Tests for the development of a metals recovery technology from samples of a Russian gold-bismuth deposit were carried out. Gold, silver and bismuth assay reported 5.6 g/t, 3.0 g/t and 0.08 per cent, respectively. Two flow sheet options were pilot plant tested: gravity/cyanidation of gravity tailings with subsequent flotation of cyanidation/carbon-in-pulp (CIP) tailings, and gravity/flotation concentration with cyanidation/CIP of concentrates. Option 1 results showed lower gold, silver and bismuth recoveries (81.3 per cent Au, 55 per cent Ag and 74.0 per cent Bi) due to low flotation efficiency for cyanidation tailings. Therefore, a flow sheet involving gravity/flotation concentration to produce bismuth-gold concentrates (0.8 per cent Bi) with subsequent cyanidation/CIP was recommended. Gold, silver and bismuth recoveries obtained by this method to the combined gravity/flotation concentrate were 90.2 per cent Au, 83.3 per cent Ag and 80.2 per cent Bi of the ore, respectively. Overall gold, silver and bismuth recoveries were 83.0 per cent Au, 40.5 per cent Ag and 80.2 per cent Bi, respectively. Gold and silver recoveries to the cathode precipitate were 92 per cent Au and 48.6 per cent Ag (per operation). Reagents consumed for flotation were 0.1 kg lead acetate/t ore, 0.4 kg butyl xanthate/t ore, 0.2 kg T-80 frother/t ore, 0.02 kg sodium hexametaphosphate/t ore, 0.15 kg copper sulfate/t ore. Reagents consumption for cyanidation was 0.42 - 0.48 kg NaCN/t ore and 0.2 kg CaO/t ore. It was recommended to deliver bismuth concentrates after hydrometallurgical treatment to a smelter. Overall bismuth recovery including bismuth recovery achieved by pyrometallurgy was 60.0 per cent. However, it was obvious that delivery of bismuth concentrates to a smelter and their commercial treatment would be very expensive due to relatively high mass pull of bismuth concentrates (7.6 per cent of the ore weight). For this reason, thiourea leaching and hydrochloric acid leaching with subsequent cyanidation/CIP were investigated as alternatives to cyanide leaching. These two alternatives were proposed to enable optimal recovery of valuable metals from concentrates on-site. Recoveries obtained by thiourea leaching were 91.2 per cent Au, 90.5 - 91.9 per cent Bi and 77.0 - 78.1 per cent Ag. However, that method required considerable capital and operating costs. As an alternative, hydrochloric acid leaching with subsequent cyanidation was investigated. Test results showed improved gold, bismuth and silver recoveries, which were 94 - 95.9 Au per cent, 94 - 96 Bi per cent and 76 - 78 Ag per cent, respectively. Hydrochloric acid consumption was 100 kg/t concentrate or 7.6 kg/t ore. Current efficiency during electrowinning was about eight to 12 per cent. A recommended flow sheet involving hydrochloric acid leaching of concentrates, electrowinning of bismuth from solutions, recycling solutions after electrowinning and cyanidation of hydrochloric acid leaching cakes is described. Overall recoveries achieved by the proposed flow sheet were as follows: 84.8 - 86.5 Au per cent, 75.8 - 76.9 Bi per cent and 63.2 - 64.9 Ag per cent. Based on results from these tests, initial data for a bankable feasibility study and plant designing were developed.

Jan 1, 2007