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Since the mid-1970s there has been increasing attention in the South Pacific area to the problems of disaster planning and management at various levels, mainly from regional through national to provincial levels. This concern has been expressed in a variety of ways. International aid donors have made their views known in commentaries or reports. Seminar discussions have been organised at the regional level (such as at Suva, 1976; Suva, 1979; Tonga, 1982 and Suva, 1983). In-country training workshops or meetings have been organised (such as the "Disaster Preparedness Workshops for Non-governmental Organisations" in Pacific countries, jointly run by the Australian Red Cross and the Australian Overseas Disaster Response Organisation and supported by AIDAB, in Vanuatu, 1985; Solomon Islands, 1985; Western Samoa, 1986; Fiji, 1987; Tonga, 1987; Lae and Port Moresby, Papua New Guinea, 1988) or held outside the area (ACDC at Macedon, 1981). Training and/or research institutions have been established such as the East-West Center, Honolulu, and the Asian Disaster Preparedness Center, Bangkok (more Asia oriented). As part of the East-West Center Pacific Islands Development Program's Disaster Preparedness Project, a detailed manual of disaster preparedness and response procedures and guidelines has been published (Carter, 1984).Table 1 and figure 1 show that the area with which this discussion deals is a highly fragmented island region, comprising many small, some minute, nations, both in land area and population. The social structure is predominantly rural, with the capital city often making up a small part of the total population and, in absolute terms, little more than a small town. Outside the administrative and governmental activities concentrated in the capitals, in most cases the indigenous inhabitants depend on subsistence agriculture or on usually a monocultural concentration on a cash crop, most frequently coconuts.

Jan 1, 1990

Although laterite ores already provide a significant proportion of the world's nickel and cobalt production it is anticipated that they will surpass sulphide ores as a source of nickel in the next century. The most recent period of greenfield nickel project construction was during the 1970s when it was notable that all of the eight new plants were based on treating laterite ores. This was because of the relatively large selection of available high grade laterite ore deposits amenable to cheap open cast mining and a paucity of high grade sulphide ore prospect alternatives. Of the three processing options for treating laterite ores: 1. smelting for the lower horizon saprolite ore, 2. ammonia; and 3. acid leach for the upper horizon limonite ore, smelting currently accounts for about 80 per cent of nickel production. In the future, as saprolite ore grades decline because of relatively high exploitation rates, the incentive to process the large untapped reserves of limonite ore will increase. The high cobalt content of limonite ore also makes it ideally suited to processing by a hydrometallurgical rather than smelting route. With only two exceptions, all saprolite smelting operations have a Class 2 nickel end product (largely ferronickel) and do not produce a cobalt by-product. As a result of technological advances, the modified ammonia leach process for limonite and transition ore as undertaken at Yabulu, now allows the production of pure nickel metal as a Class 1 product, along with significant tonnages of cobalt by-product. The mixed Ni-Co sulphide intermediate product of the pressure acid leach processing of limonite ore at Mon is converted to Class 1 nickel and cobalt metal at Fort Saskatchewan, Canada.

Jan 1, 1996

By Frith RT, M D. Goodz

Drilling has been accepted as a major exploration tool. However its use in mine planning and development has been overlooked.This need for drillhole data was highlighted during the redevelopment boom of the central Victorian gold mines. During the 1980's numerous old mines were evaluated and successfully drilled to yield mineable parcels of quartz reefs close to existing workings.Invariably the initial decision was always to attempt reopening and rehabilitating existing access. The four case studies described have proceededsufficiently to show that major cost savings would have been made if underground drilling had been used as the main tool in mine planning.Savings not only in expenditure, but in the time required to make key decisions. In two cases the mines would have experienced far earlier expansions in production. In one case the mine would be currently producing rather than awaiting further finance. In the fourth example, the decision to case development would have been much earlier providing capital to other projects.

Jan 1, 1990

By Miyatani J. Asaki Z, Kondo Y

The oxidation of sphalerite particles of 60 to 100 mesh size was studied in a fluidized bed of low 02 concentration at 900¦C. Par- tial pressure of 02 in the fluidizing 02-N2 gas mixture was chosen between 0.0009 and 0.02 atm. In the region of p02 between 0.008 and 0.02 atm, the oxidation rate was lowered with the decrease of p02, and the unreacted-core model was applied. At lower pbelow 0.008 atm, the reaction rate was enhanced as compared with the calcu- lated values from the unreacted-core model. From microscopic examination, it was found that ZnS was evaporated at the particle surface and the dissociated Zn vapor was oxidized in the gas phase. Initial reaction rate and the distance between the surface of inner sphaler- ite core and the oxide shell were studied based on the model of enhanced oxidation.

Jan 1, 1980

By Adshead ND, Blake KL, Rotherham JF, Rotherham M, De Jong G

Magnetite deposits with distinctive ¦ actinolite ¦ apatite -bearing gangue and spatially-extensive sodic-calcic wall rock alteration occur in both Proterozoic metamorphic terrains and Mesozoic-Tertiary magmatic arcs. Examples from both settings constitute significant sources of iron ore (e.g. Kiruna, Sweden; El Romeral, Chile) and some host major Cu-Au deposits that have a local association with K-silicate alteration (e.g. Cloncurry district, NW Queensland; Copiapo district, Chile). A growing body of evidence points to a hydrothermal origin for these systems involving high temperature, low S oxidized fluids. The Cloncurry magnetite-Cu-Au deposits are products of the local structurally channelized influx of a specialized high salinity ore fluid into larger-scale alteration systems developed during pluton emplacement at greater depths than those associated with subvolcanic (porphyry) Cu-Au deposits. The geological characteristics of deposits in magmatic arcs are consistent with a similar mode of origin albeit in rather different tectonic settings.

Jan 1, 1995

Kamhalda is located within the Yilgarn Craton of Western Australia, specifically in the Norseman - Wiluna greenstone belt. Numerous nickel sulphide deposits have been mined at Kambalda with I I mines currently operating. For several years, a program of in-mine geophysics has been operating at Kambalda, with downhole electromagnetics (UHEM) one of the key techniques used. Three case studies illustrating the uses of UHEM in mines are presented here. In the first example, the Helmut South deposit was discovered as the result of an extensional exploration program. The first drill hole in the program intersected ore width and grade mineralisation at around 760 in depth. Two subsequent holes intersected subgrade mineralisation. DHEM surveys were completed in each of these three holes, with anomalies recorded indicating that a large conductor was located directly south of the first hole. The next hole intersected this target, for an intersection of 21.6 in at 3.5 per cent Ni. DHEM continued to play a role as the exploration program proceeded, providing drill hole targeting based on anomalous responses recorded in each drill hole. In the second example from Carnilya Hill, old drill holes were surveyed with DHEM in order to search a large section of prospective contact for massive ore pods. An off-hole anomaly was detected and subsequent mining discovered a small but high-grade pod of ore which was extracted for a considerable profit. Carnilya Hill has limited reserves and discoveries such as this, assist in keeping the mine operating. In the third example from Victor, a program of drilling intersected thin ore profiles in an interpreted flanking position. Without massive ore close by, these intersections probably do not constitute economic mineralisation. DHEM surveys of three holes did not detect any conductors. The area is now regarded as sterilised of significant massive ore and exploration efforts and dollars can be focused in other areas. These three examples demonstrate the type of successes that can he achieved through the use of DHEM.

Jan 1, 1997

By S McKnight, S Hall

Much of the research regarding the use of bacteria for the oxidation of sulfide minerals has been conducted using pure bacterial strains or synthetic minerals, often under ideal conditions, which does not reflect the conditions commonly encountered in commercially operating plants. This has also led to much conjecture as to the exact mechanism by which bacteria are able to enhance sulfide oxidation and as to which species of bacterial microflora are the most dominant. Recent advances in 16S rNA sequencing has confirmed that many of the bacterial species once thought to dominate commercial oxidation circuits were simply more willing to grow under the culturing conditions used and may only play a minor role in the oxidation process (Rawlings, 2002). Consequently this research will look at bacterial oxidation under conditions more reflective of commercial operations, focusing on the presence of organic carbonaceous material within a refractory sulfide orebody to be sourced from the Fosterville deposit of Perseverance Corporation Limited.

Jan 1, 2004

By R C. Morris

The channel iron deposits (CID) (Ramanaidou, Horwitz and Morris, 1991; Morris, Ramanaidou and Horwitz, 1993; Ramanaidou, Morris and Horwitz, 2003; Morris and Ramanaidou, 2007) are one of the two major iron ore types mined in the Hamersley Province. The CID provided around 41 per cent of the total of 268 Mt of iron ore mined from the Hamersley Province in 2006. The current CID resource is around seven billion tonnes. The CID deposits occupy numerous meandering palaeochannels in a mature surface that includes Precambrian rocks and ferruginous palaeogene valley fill. These palaeochannels are generally less than a kilometre but can range to several kilometres in width and from one metre to more than 100 m thick. The two currently mined CID areas are located:in the western Hamersley Province in the Robe palaeochannel, and in the east in the Yandi palaeochannel. These two major CID channels extend over 100 km to 150 km, with the Robe system up to 5 km wide. The granular ore facies typically contains ooids and lesser pisoids with haematite nuclei and goethite cortices, with abundant goethitised wood/charcoal fragments and goethitic peloids, minor clay and generally minimal porous goethitic matrix. Post deposition weathering is common and produced secondary facies.Ooids and pisoids were mostly derived from the stripping of a well- vegetated deep ferruginous surface. The peloids were derived both intraformationally from fragmentation and reworking of desiccated goethite-rich mud. Minute wood/charcoal fragments in the soil that were initially replaced by goethite and then dehydrated to haematite, formed nuclei for many ooids and pisoids. In addition, abundant, generally small (in situ by goethite within the consolidating CID. This profusion of fossil wood, both as ooids and pisoids nuclei and as discrete fragments as well as the local presence of kenomagnetite suggests major episodic wild fires in heavily vegetated catchments. The goethitic matrix was the result of chemically precipitated iron hydroxyoxides, resulting from leaching of iron-rich soils in an organic environment.

Jan 1, 2007

By Cunningham CG

Many epithermal gold-silver deposits areknown to occur in the Neogene-Quaternary volcanic complex of the central Andean region of southern Peru, northern Chile, western Bolivia, and north-western Argentina, an area of about 300,000 km2 where these volcanic rocks constitute the dominant cover. Some of the gold-silver deposits were mined during Spanish colonial times, as early as the 16th century,- whereas others were not discovered until the 19th and 20th centuries. The extraordinary gold-silver potential of this young volcanic complex, however, was not recognized until the 1970's when the phenomenal increase in gold and silver prices stimulated new exploration. New discoveries were made, chiefly in southern Peru and northern Chile, of high-grade ores in old mining districts and large low-grade ore bodies, both in old districts and in new areas having no history of mining activity. Many additional gold and silver deposits remain to be discovered within and beneath the young volcanic complex of this region.

Jan 1, 1990

By T Mizuta, H Satoh, M Ogasawara, M Miyata, M Fukuyama

The Miocene Chichibu granitoids associated with the Chichibu skarn deposit are divided into North Body, South Body and Daikoku altered stock. Orebodies of the Chichibu skarn deposit are mainly distributed in the north-western part of the North Body and Daikoku altered stock. The North Body consists of magnetite-series granitoids ranging from tonalite to granodiorite and to monzogranite from the margins to the centre of the intrusion. The South Body consists of tonalite and granodiorite, and most of these rocks are also classified as magnetite-series granitoids. The Daikoku altered stock consists of a quartz diorite porphyry. The SiO2 contents of the granitic rocks of the North Body and South Body range from 61.6 to 70.7 wt per cent. During magmatic differentiation, Cu, As and Zn contents in fresh granitic rocks of the North Body and South Body increase with SiO2 content up to 63 wt per cent SiO2, and then progressively decrease with increasing SiO2 contents as SiO2 exceeds 65 wt per cent. Estimated pressure for the emplacement of the granitoids is about 0.5 kbars. Cathodoluminescence studies on quartz from those granitic rocks show that vapour rich two-phase fluid inclusions tend to occur in the core of quartz crystals, while halite-bearing poly-phase fluid inclusions occur in the margins of quartz crystals. The distribution of fluid inclusions suggests that fluid composition changed from low to high salinities during the growth of magmatic quartz crystals. Texture showing quartz crystals with an oval shape enclosed by radial aggregates of a mixture of fine-grained quartz, plagioclase and K-feldspar composing the groundmass of the monzogranite also suggests a pressure decrease during solidification of North Body. These findings show that high salinity fluids were present during magmatic differentiation and that Fe-Cu-Pb-Zn-Au-Ag skarn mineralisation of the Chichibu deposit was possibly associated with these high salinity fluids. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By M J. Ireland, D P. Horne, S J. Simpson

The Sinclair Nickel Project, wholly owned by Xstrata Nickel Australasia (XNA), includes an underground mine, a concentrator, a village, an all-weather airstrip and associated mine infrastructure. The operation is located 70 km north of Leonora in the prospective and historically productive eastern Goldfields region of Western Australia. Xstrata Nickel has successfully developed the Sinclair deposit into a 350 kt/a operation since its discovery in November 2005, with contained nickel metal production to date in excess of 10 600 t, of which 5500 t is from the underground operation.The narrow, continuous, medium-grade Sinclair nickel sulfide deposit accessed by the Phoenix Decline has a shallow 15¦ - 20¦ plunge that is approximately 1000 m long down dip and open at depth to the north. The flat plunge and low-grade nature of the orebody presents challenges regarding the amount of horizontal waste development that can be economically excavated, which in turn affects ventilation, egress, mine services and diamond drilling.The mineralisation is hosted between an ultra mafic hanging wall and a basalt footwall and is being mined using a bottom up, sublevel open stoping method. The stopes are retreated to a central access, filling voids in the process with waste mullock where possible and using cemented mullock fill where end exposure is required. Tight filling the flat dipping hanging wall has proved to be challenging given the angle of repose for the waste mullock fill is steeper than the angle of the hanging wall.Reconciliations of mine performance against the original feasibility study show positive changes and operational optimisations enabling Sinclair to achieve its mining targets in a safe, sustainable and economic manner. This paper discusses the mining operations associated with the first two years of the Sinclair Underground Nickel Project, providing an overview of the various issues encountered and the lessons learnt in the process.CITATION:Ireland, M J, Horne, D P and Simpson, S J, 2012. Overcoming mine design and production challenges at the Sinclair underground nickel project, in Proceedings Narrow Vein Mining 2012 , pp 37-48 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

The Electricity Commission of New South Wales is the largest single user of coal in the State, burning some 8.5 million tonnes during 1972-73. This coal is converted in power stations into electrical energy which is then distributed throughout the State and supplies the electricity requirements of 99% of users in New South Wales. Barring any major change in energy consumption growth, or change in the current mode of power generation, the consumption of coal by the Commission is estimated to have a doubling period of from 10 to 14 years. Coal is used to generate up to 87% of the electrical energy sold, the balance being obtained from hydro gen- eration, mainly in the Snowy Mountains, and, to a much smaller extent, from diesel generation at Broken Hill. A very large proportion of this coal is consumed in pulverised fuel boilers in the Commission's power stations, located mainly on the various coalfields of New South Wales. Coal supplies are drawn from a large number of mines, some owned or controlled by the Commission, others being owned by public companies. The coals used, originate from at least ten different seams located in the northern, western and southern coalfields of New South Wales, and therefore have a wide variety of properties and characteristics. To ensure an adequate fuel supply well into the future, the Commission is continuously engaged in coal prospecting in various areas. Bore data is used in assessing coal reserves and is also the basis of economic studies for their possible future exploitation. The numerous coal cores obtained during drilling operations are carefully tested and analysed in order to assess their suitability for power generation purposes, and to provide data for the design and operation of boiler plant using these coals. In existing power stations coal deliveries are systematically sampled and tested for quality control, for pay- ment of purchases based upon certain quality parameters and to check for any possible plant operating or main- tenance problems that might arise from the use of the particular coals. Almost all the properties of coal that may be necessary in the Commission's work are obtained using standard testing procedures carried out by the Commission's chemists, in laboratories located at the various power stations or at its Central Laboratories in Pyrmont. Where specialised analysis or testing is required, this is ordinarily undertaken on a commercial basis by outside bodies, expert in the particular field. The significance of the various properties of the coal for use in p.f. boilers is outlined and related to their proper application to boiler plant design and to plant operation.

Jan 1, 1975

Drainage aids are designed to assist in filter cake dewatering by reduction of surface tension. By the early 1980's severalspecialist chemical manufacturers had developed drainage aids specific to the alumina industry. Thus, after some initial laboratory work, drainage aid addition to the product hydrate filter cake was first tried at Gove in early 1981. Encouraging results led to further plant trials and a laboratory trial comparing eight different products. Fromthis last trial a product was chosen and a plant trial run in March 1982. The results achieved encouraged a further plant trial to be run during April and May, 1982 and a decision was then made to adopt the full-time use of drainage aid on the plant.Optimisation work with the drum filters and drainage aid continued until late 1983. This work not only led to optimisation of dose rates, concentrations etc., but also to significant improvements in the mode of operation of the product filtration area.

Jan 1, 1985

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

Underlain by and intruded into the sedimentary rocks of the Transvaal Supergroup the Bushveld Complex is the largest known layered intrusion in the world and contains one of the richest ore deposits on earth. It has been the world's major source of Platinum Group Metals (PGM) since the mid-1900s with Chromite and PGMs the two most economically important components of the Bushveld Complex. The lower group (LG), within the critical zone, consists of seven chromitite layers and it is within this sequence of chromitite layers, the most important target of the lower chromitite group is found, ie the LG6 chromitite unit. The LG6 chromitite unit consists of a chromitite duplex composed of the lower LG6 chromitite layer (Steelport seam), averaging 1 m thick, overlain by a 0.66 m waste parting and a thin 0.34 m thick LG6a chromitite layer (leader layer).Two mining methods are commonly applied in the Bushveld Complex to extract the LG6 chromitite layer package. One method consists of footwall development utilising rail bound equipment to gain access to the orebody and then extracts only the LG6 chromitite layer by means of hand held rock drills and scraper winches. The second method is the use of mechanised equipment to access the orebody on the plane of the ore utilising bord and pillar mining method, which extracts the full mineral resource, ie the LG6 and LG6a layers. Conventional narrow vein stoping is often selected due to the large conventional mining skills base found in South Africa, the perceived cost and dilution implications of utilising mechanised equipment, and the difficulties of using mechanised equipment at dips above 12¦. The driving factor for mechanised mining is the perceived ability to access the orebody quickly and inexpensively, and extract the entire mineral resource package (LG6 and LG6a) while limiting capital expenditure and improving safety.This paper investigates these two commonly applied approaches, highlighting the benefits and problems associated with the two approaches. Comparisons will be made of the two mining methods and recommendations given for the mining engineer to consider before selecting the appropriate mine design.

Dec 6, 2010

By N J. Betts

This paper aims to build on the strong emphasis that was placed on safety in the Sydney AITES-ITA Congress in March 2002. It will do this by comparing safety records from some major tunnelling projects in Europe and Australia over a period commencing in the second half of the 19th century to the second half of the 20th century and examining reasons for the apparent marked improvement that appeared in the 1980s. Further by looking at the relationship between this improvement and current trends in the australian industry by means of a detailed review of the safety record for the Northside Storage Tunnel project in Sydney which was completed in mid-2000. The paper will conclude by providing a summary of the progressive approach adopted by the minerals industry in australia and summarising the current state of tunnelling and underground construction in australia with respect to recently completed projects and potential major initiatives.

Jan 1, 2003

Depending upon the probability one assigns to project go-ahead, up to $10 billion (1978 figures) could be required for resource based projects in Australia in the next decade. In the past major resource projects were readily financeable against sales contracts. In the future the complexities imposed by such matters as political risk, inflation, currency movements and environmental and other socio- economic considerations on project development costs and returns may require a different approach. This paper addresses itself to the ramifications of providing development finance for resource based projects in the future - and in particular examines such factors as project completion guarantees, sales contracts, protection against exchange rate fluctuations, interest rate structures and debt/equity ratios as each relates to the provision of finance. TABLE OF CONTENTS SECTION 1 : Introduction SECTION 2 Factors Affecting Project Financing in the Next Decade SECTION 3 Some Aspects of Financing New Projects in Australia in the 1980's Conclusion

Jan 1, 1979

By S K. Michelic, N Preisser

For certain applications, steels have to feature a very distinct and well-defined level of cleanness in terms of the number and composition of non-metallic inclusions. Therefore, one crucial aspect of steelmaking is removing and controlling said non-metallic inclusions during the process. Particle removal during ladle refining comprises three stages, namely: 1. Flotation 2. Transport through the steel/slag interface 3. Dissolution of the particle in the slag. Only if all three stages are completed the particle can be considered as fully removed from the steel melt which, in turn, leads to the slag being one of the most influential parameters for inclusion removal and control. Depending on the composition of the particles and the slag, the dissolution can be controlled by different mechanisms. This study focuses on the diffusion-controlled dissolution of solid oxidic particles in slags. For this, a model of particle dissolution has been developed. For modelling diffusion, either the differential equation following Fick’s second law can be solved, or an analytical solution to this equation valid for stationary interfaces can be used. Both approaches allow for calculations of concentration profiles of the dissolving species in surrounding slag. From this, the mass flux can be derived, which finally leads to calculating the boundary layer velocity due to considerations of mass balance. In this work, both methods as well as results of dissolution experiments using High Temperature Confocal Scanning Laser Microscopy are compared. This research aims to provide a framework for diffusion-based dissolution modelling in further expanding the understanding of particle dissolution in secondary metallurgy.

Aug 21, 2024

By R M. Tosdal

Intrusion related ore deposits are widespread in the Central Peruvian Cordillera Occidental and adjacent high-plains to the east and include porphyry Cu (-Au, Mo; eg Morococha), Cu-Zn (Pb-) skarn (eg Antamina), Pb-Zn-Ag carbonate hosted vein deposits (eg Uchucchacua), cordilleran base metal (eg Cerro de Pasco) and epithermal deposits (eg Quicay). Geochronology and petrochemistry of intrusive rocks associated with mineralisation reveals that: most ore deposits were emplaced in the late middle to early late Miocene; and are related to calc-alkaline granodioritic igneous rocks with Sm/Yb >3, Sr/Y >40 and Y/Th <1.5. The largest deposits, including Antamina, Colquijirca and Cerro de Pasco are associated with intrusions with Sm/Yb >4 and which, as indicated by Pb and Sr isotopic data, have undergone relatively moderate middle and upper crustal assimilation. The chemical signature of igneous rocks related to mineralisation likely reflects melt equilibration in the lower crust at a crustal thickness of more than 45 km. Mineralisation was favoured by a change from normal to flat subduction, resulting in increased compression, crustal thickening and subsequent cessation of the magmatic arc. Premiocene ore deposits do occur, but are restricted to a broad E-W corridor between Uchucchacua and Milpo and probably were controlled by a crustal-scale structural discontinuity across the strike of theAndes. Not all igneous rocks with high Sm/Yb and Sr/Y ratios did acquire their trace element signature in the lower crust. Petrographic and Pb isotopic evidence indicates shallow crustal hornblende fractionation or assimilation of pelitic material as possible causes for high trace element ratios in some rocks. These are apparently unrelated to polymetallic mineralisation. Thus, critical evaluation of petrographic and geochemical data in metallogenetic studies, especially in areas with complex basement architecture such as Central Peru is critical and should not be reduced to simple trace element ratios. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Quast K. B

The ore used in this test program was a composite sample from Waihi, New Zealand containing 2.7 g/t gold and 36 g/t silver. From the testwork it was found that a high concentration of sodium cyanide (0.1 per cent) was necessary to ensure a high recovery of both gold and silver. There appeared little chance for either differential leaching or adsorption of gold and silver. The addition of bentonite clay decreased the rates of gold and silver dissolution. The addition of 50 g/1 NaCI had little influence on the rate of silver extraction. The addition of 5 g/l carbon gave adsorptions of 70 per cent of the gold and 35 per cent of the silver, indicating the possible presence of base metal cyanides in solution. The addition of excess sodium sulphide only precipitated 70 per cent of the silver in solution, adding further evidence to the presence of base metal sulphides. The production of separate silver and gold products was not possible by either preferential leaching, preferential adsorption of gold on carbon or preferential precipitation of silver.

Jan 1, 1991