Search Documents

By D. T. White

"Metallurgical extraction processes often call for the heating of aqueous slurries. Indirect heat exchangers are generally not feasible for service with high yield stress slurries because of low heat transfer rates. It is more appropriate to heat the slurry by direct contact, typically with steam as the heating medium. Although having a long and successful history, direct-contact heat transfer to aqueous slurries has been used without the support of pilot plant research. This paper provides results of the needed research, the work being done at a scale large enough to enable direct scale up to commercial operations. A pilot plant heater was constructed and tested to develop an understanding of the slurry heating process and to ensure that commercial scale heaters were appropriately sized.INTRODUCTIONPressure Leaching OperationsPressure leaching operations are often used to oxidise sulphide gold ores, or for extraction of nickel and cobalt from laterite ores with sulphuric acid. Where there is sufficient sulphur available, the exothermic pressure oxidation reactions can be self sustaining at temperatures as high as 225 ºC, without having to preheat the feed slurry. At lower sulphur levels, slurry preheating is required. This is typically achieved by utilising the flash steam released from the slurry letdown stages and contacting this directly with cold incoming slurry ahead of the autoclave. The vessels where this slurry-steam contact is made are known as heaters or condensers, with the number of pre-heat stages varying, depending on how much heat is evolved in the oxidation reaction (Mason, 1990).In nickel laterite pressure acid leaching processes, which operate between 245 and 270 ºC, the only significant exothermic reactions are those associated with dilution of sulphuric acid in the leach. As a consequence, slurry preheating with flash steam is always used commercially. In practice the number of flash steam preheating stages required varies from 1 to 3, driven by a number of factors, including other uses for flash steam and the upper temperature limit at which preheated slurry can be pumped. A diagram of a typical pressure acid leach train is shown in Figure 1.For pressure acid leaching operations and at low sulphur levels in pressure oxidation, boiler generated direct steam addition to the autoclave is required to sustain the reaction temperature. For this reason it is imperative that the flash steam – slurry heat transfer is efficient and the slurry temperature approaches that of the flash steam closely."

Jan 1, 2012

By Jaeheon Lee, Junmo Ahn, Doyun Shin

"Many alternative leaching systems including bacterial leaching have been introduced to avoid passivation on the surface of chalcopyrite and to increase the leaching efficiency of copper from chalcopyrite. Recently, glycine, one of the simplest amino acids, has been emerging as an efficient and environmental-friendly lixiviant to recover copper. In the present study, an alkaline glycine–peroxide lixiviant system was used to leach copper from chalcopyrite concentrate and the leaching mechanisms were also investigated by a suite of kinetic studies under different conditions. The chalcopyrite concentrate contains 28.8% copper with 30.8% sulfide sulfur. The effect of concentration of glycine and hydrogen peroxide of the leaching solution was investigated. Glycine concentration was varied from 0.5 to 1.0 M and the hydrogen peroxide concentration was changed between 3 to 5%. Leaching time and pulp density were also varied. Hydrogen peroxide is an oxidant of the system and the leaching efficiency with periodic additions of the peroxide was also studied. A mineralogical study was performed using XRD and SEM. To investigate the surface of the residue materials, XPS was used to see if any passivating layer was formed during the leaching. Detailed results from mineralogical, chemical, and metallurgical studies will be presented and discussed.INTRODUCTION The greatest global resource of copper is low-grade chalcopyrite and heap bioleaching may be the only economic option for its processing. However, formation of a passivating layer on the surface of chalcopyrite slows down the oxidation reaction and reduces the efficiency of the process."

Jan 1, 2017

By E. Ghali, W. Zhang, M. Robichaud, G. Houlachi

"The performances of six mesh and one plate dimensionally stable anodes have been investigated in the zinc electrolyte at 38oC and compared to conventional silver-lead alloy anodes. The electrochemical behaviour of these anodes was studied by cyclic voltammetry, galvanostatic, potentiodynamic, open circuit potential and electrochemical noise measurements. It was observed that at the end of 24 h of galvanostatic polarization at a current density of 50 mA/cm2 in the zinc electrolyte at 38oC, the mesh V had the lowest potential followed by mesh III, mesh VI, plate-V, mesh IV, mesh I, and mesh II electrode. When the potentials for mesh I, mesh III, mesh IV, VI and plate-V, mesh V were compared with that of the Pb-0.7%Ag anode (1920 mV/SHE), they were found to be 6%, 16%, 7% 10%, 17% lower, respectively.After 16 h decay following the 24 h polarization, the mesh III had the lowest corrosion rate (51 mS/cm2) among the seven specimens, followed by the plate-V, mesh V, VI, IV, I and II (221 mS/cm2). For the fresh surface as received, after two hour open circuit potential measurements, mesh I had the most positive (noble) potential (1382 mV/SHE) among the seven electrodes followed by the plate-V electrode, mesh V, mesh IV, mesh VI, mesh III and mesh II (751 mV/SHE). After consecutive series of electrochemical testing, mesh V, mesh III, mesh VI had lower corrosion rates (~ 343± 6 µA/cm2) than that of mesh IV, mesh I, plate-V, and mesh II (~ 644± 143 µA/cm2).INTRODUCTIONThe continued use of lead based anodes in the electrowinning process has been mainly due to their relatively low cost as compared to other materials (Msindo, Sibanda, & Potgieter, 2010). They have good electrical conductivity, stability during electrolysis, very good corrosion and wear resistance (Ivanov, Stefanov, Noncheva, Petrova, Dobrev, Mirkova, Vermeersch, & Damaerel, 2010). However, lead-based anodes give their high energy consumption and low corrosion resistance for electrowinning. To overcome these problems, Dimensionally Stable Anodes (DSAs) has been chosen (Msindo et al., 2010). Comparing to the traditional lead anodes, the DSA anodes have many advantages: (1) no contamination; (2) no loss of anode material, pure electrolyte; (3) lower gas bubble effect through special anode designs; (4) use of higher current densities (Msindo et al., 2010). The success of DSA anodes has been attributed to their chemical stability that allows them to maintain nearly constant dimensions during the life of the anode even when operating in environment with low pH values. Due to their stability, the consumption rates of DSA are as low as 1 mg/amp.y (Alfantazi & Moskalyk, 2003)."

Jan 1, 2016

By J. G. A. Stevenson

GENERAL Location of Property THE Stirling zinc-lead-copper deposit is in Richmond county, Cape Breton, about a quarter of a mile southwest from Stirling P.O., and some 45 miles southwest from Sydney. The property is accessible by road for at least nine months of the year, and during the navigation period coastal boats maintain a service touching at the port of Fourchu, eleven miles from the mine. When flying conditions permit, the Cape Breton Flying Club, of Sydney, will carry passengers to or from the property, a service which has been particularly advantageous on two occasions when hospitalization was urgently required. The Company has mining rights on leases Nos. 73-74, 78-80, and 101-104, inclusive, and owns 166 acres at Stirling and one acre at Fourchu. The ore deposit is in lease No. 73. History The Stirling deposit was discovered in the 'nineties', probably about 1895. The original discovery is said to have been made in the bed of Copper creek, which traverses the ore-zone. For a number of years, indifferent development work was carried on with a view to copper production only, and it was not until1915-16 that attention was directed to the possible production of zinc. Previously, the ore had been considered too complex for metallurgical treatment. During the period 1916-24 several operators attempted to develop the property, among them being the Stirling Exploration Company, Stirling Mining & Smelting Company, New Jersey Zinc Company of New York, Hayden & Stone Company of Boston, and The Eastern Mining & Milling Company. Up to 1924, the work was limited mainly to trenching, stripping, ? diamond drilling, and shot drilling.

Jan 1, 1937

By D. J. Hains

IN this paper we shall examine the Why, Where and How concerning the agglomeration of iron ores and concentrates. Fig. l answers the questions @f why there is so much interest at the present time in the art of agglomeration. The use of sinter or pellets in the blast furnace has materially increased their rated •capacity. ':'President Hains Company Ltd. Engineering J. S. McMahon ( 1) reports an increase from 653 tons of .pig iron per day to 1140 tons of pig iron per day with the use of a 100 per cent sinter burden on one of his blast furnaces. In the United States the use of 100 per cent pellets has increased pig iron production from approximately 1800 tons per day to over 3000 tons pig iron per day (2). In our economic system the general objective is to produce more and better commodities cheaper. Fig. 2 shows the decrease in coke consumption with increased tonnages from the furnaces when using -

Jan 1, 1961

By E. L. Bruce

Introduction The Outokumpu copper mine is situated in eastern Finland, 50 kilometers west of the city of Joensuu or 225 kilometers directly north of the city of Viborg (Viipuri), which is situated at the eastern end of the gulf of Finland (Figure 1). The ore-body was discovered in 1910 by Dr. Otto Trüstedt after two years of careful, scientifically-directed, search. During the early period of development of the mine, the ore was treated locally and the copper re-covered by an electrolytic process. Now the ore is concentrated by tables and by flotation. The concentrates are shipped to Germany for refining. In 1929 the mine produced 150,000 tons of ore from which between 20,000 and 25,000 tons of flotation concentrates containing 20 per cent copper were produced. Profits in 1929 were approximately half a million dollars, but the present price of copper will affect very seriously the profits for 1930. The ore reserves are given as between 7 and 8 million tons (1). The grade of ore is stated to be 4 percent to 6 percent copper, with a little zinc.

Jan 1, 1931

By Lebeau M., P. Duguay

"The cost of occupational injuries and diseases in the mining industry in Quebec was estimated for the period of 2010 to 2012. The method used takes into account the financial and human costs assumed by employers, workers, and the community. To better direct research and prevention toward issues with the most significant consequences, the results are presented in various ranking tables, which stakeholders might find useful.RÉSUMÉ Le coût des accidents du travail et des maladies professionnelles dans l’industrie minière au Québec a été estimé pour la période 2010-2012. La méthode utilisée prend en compte les coûts financiers et humains endossés par les employeurs, les travailleurs et la communauté. Afin de mieux orienter les recherches et la prévention vers les problèmes ayant les plus graves conséquences, les résultats sont présentés dans divers tableaux de classement, qui seront d’une grande utilité aux parties prenantes. INTRODUCTIONThe mining industry is much safer today than it was 30 or 40 years ago, mainly due to a more qualified workforce, the use of automated equipment, and a corporate culture more focused on occupational health and safety (OHS); however, the number and the severity of occupational injuries and diseases continue to make this industry one of the most hazardous. In the province of Quebec, the mining industry accounts for approximately 0.4% of paid workers but is the source of 4% of fatal work accidents. It is, therefore, important to continue the prevention efforts already underway in the mining industry.The difficult global economy, which has affected the mining industry in the last few years, is an opportunity to reaffirm that sound management of OHS can have a positive impact on companies’ productivity and profitability. Occupational injuries and diseases are costly for the companies concerned and for society as a whole. Reducing their occurrence makes it possible to reduce not only the size of workers’ compensation board contributions but also several other financial and human costs."

Jan 1, 2018

By K. C. Grogan

"GeneralGIANT ORE is complex, with the gold values for the most part occurring in extremely close association with arsenopyrite, stibnite, jamesonite, and a wide group of antimonial minerals locally termed 'the grey minerals'. Pyrite is the most abundant of the sulphide minerals• and minor quantities of chalcopyrite, galena, and sphalerite also occur. Pyrrhotite has been found in some sections of the mine, but to date none of it has been nickeliferous. Native gold occurs in varying amounts throughout the ore bodies.In 1944, ore dressing investigations were commenced on diamond-drill core rejects and samples of surface outcrop ore. Results soon indicated that treatment to produce satisfactory recovery of the gold values would involve fine grinding to 80-85 per cent minus 200 mesh, recovery of free gold by jigs, followed by flotation, roasting of the flotation concentrate, and subsequent cyanidation of the calcine. Proceeding from this information, the flow-sheet was prepared, plant design worked out, equipment purchased, and construction of the treatment plant commenced in May, 1947.The crushing, grinding, and flotation units of the plant were rushed to completion and commenced operation on May 12th, l.948, at 225 tons of ore per day. This rate was maintained until January 27th, 1949, when the Allis-Chalmers roaster and cyanide plants were completed and commenced operation. During the period May 12th, 1948, to January 27th, 1949, gold recovered by amalgamation was the sole source of revenue. Flotation concentrate was stockpiled pending the completion of the Allis~Chalmers roaster and cyanide plants."

Jan 1, 1953

By Mike Dry, Rod Dry

If humanity is truly serious about reducing emissions of carbon dioxide into the atmosphere, today’s power plants burning fossil fuels will have to be replaced by power plants that do not emit CO₂. Unless carbon capture/sequestration becomes practical, the new power plants will be hydroelectric, wind, solar or nuclear installations. Hydroelectricity requires the appropriate geography. Solar installations can only deliver power as and when sunshine is available, and wind installations when the wind blows. Therefore, power from these sources will be intermittent, but the demand for electricity does not follow the patterns of sun and wind. That will require large-scale electricity storage and/or load following by the remaining power suppliers, increasingly so as the use of fossil fuelled power generation declines. Modern nuclear power plants are designed for demand following. However, operating at lower than design output has a negative impact on the economics of nuclear power plants because the overall cost of the electricity they generate is dominated by capital cost. Primary (blast furnace) iron smelting is responsible for a significant part of global CO₂ emissions because the reagent used is carbon. Were it available in sufficient quantity (and at a low enough cost), hydrogen could replace carbon in the manufacture of raw direct reduced iron (DRI), using technology such as modified HYL (Tenova Hyl, 2018) or Midrex (Ravenscroft, 2017). This paper examines a scenario in which, instead of demand following, nuclear power stations are operated at their design capacities and surplus power is used to generate hydrogen in off-peak periods. This hydrogen is then used to replace carbon in the manufacture of raw steel.

Jan 1, 2020

By Gyeonghye Moon, Inhyeok Choi, Jyothi Rajesh Kumar, Jin-Young Lee

"This paper deals with the recovery of the tungsten and vanadium from spent SCR catalyst leach liquors by different hydrometallurgical methods. The first part consists of pressure leaching of spent SCR catalyst using caustic soda followed by metal recovery by liquid-liquid extraction. In a leaching process, the following experimental parameters were tested and optimized: NaOH, particle size of feedstock, temperature, and solid to liquid ratio. The optimum condition for leaching of tungsten and vanadium was under the following conditions: NaOH 3 mol/L, temperature 250°C, particle size <300 µm, and solid to liquid ratio 0.4. From these optimum conditions in this experiment, the dissolution efficiency of vanadium and tungsten was 91.5and 87%, respectively. Liquid-liquid extraction following commercial extractants were tested: TBP, Cyanex 272, D2EHPA, Aliquat 336, Primeme JM-T, Alamine 308, Alamine 304-1, and methyl-tri-octyl-ammonium chloride. The conditions for both valuable metal recoveries were optimized.INTRODUCTIONSelective Catalytic Reduction (SCR) catalyst has become the most effective to reduce nitrogen oxide (NOx) emissions from stationary segments such as power plants and waste incinerations around the world due to the reinforcing regulatory trend and emerging environmental issues (Forzatti, 2001; Spivey, 2002; Li et al., 2011).Currently, the most widely used SCR catalyst is V2O5-WO3/TiO2 system due to its great catalytic properties (Li et al., 2011; Marshneva et al., 1995; Marbergeret al., 2015). In general, the composition of the SCR catalyst used in the stationary application is 0.5 to 1 wt% of V2O5and 7 to 10 wt% of WO3(Marberger et al., 2015; Chen &Yang, 1992, Vuurman et al., 1991; Alemany et al., 1991). Currently spent SCR catalysts are treated as waste and disposed of in landfills. This causes a lot of waste of secondary resources of vanadium and tungsten. In terms of industrial value of vanadium and tungsten (Gupta &Mukherjee, 1990; Moskalyk &Alfantazi, 2003) and reduction of pollutant emissions, it should not be disregarded for their recovery for their material recycling from spent SCR catalyst. However, investigations for recovery of metal values from spent SCR catalyst has been rarely carried out."

Jan 1, 2017

By John Dasher

The analyses reported on in this paper indicate that there are hydrometallurgical routes from sulphide concentrates to copper that are potentially competitive with smelters which are not permitted to emit sulphur oxides. The various hydrometallurgical processes, and their economics, are discussed.

Jan 1, 1973

By F. W. Tregarthen

"This paper gives a brief description of the methods used to form and implement the present planned maintenance program. The system is designed to assist plant personnel in their task of controlling a large work-force and maintaining the many and varied types of equipment used in a mining and concentrator operation. The types of reports and methods used in scheduling and work-loading are described. General built-in flexibility is derived from computer assistance to the Central Planning Group."

Jan 1, 1971

By H. Qi, J. L. Feng, D. J. Li

"In the present paper, the characteristics of the granite burst under loading/unloading conditions was studied by means of both laboratory experiment and finite-discrete element method (FDEM). After gaining the mechanical properties of the granite samples under uniaxial compression conditions, the parameters taken as input arguments in the FDEM modelling were then carefully calibrated so as to provide some basic data including Young’s modulus, Poisson’s ratio, uniaxial strength, Lame constants, cohesive strength, and frictional angle for further being used in simulating granite bursts. All the simulating results by the FDEM were basically in agreement with that obtained from the uniaxial compression test and triaxial granite bursts in laboratory, respectively. This study shows that that such computational mechanics of discontinua can be employed to gain powerful insight into the failure mechanism of granite burst, which could also be a useful tool to clarify the collapse mechanism of rock structures in rock engineering design and rock test scheme optimisation. INTRODUCTIONBased on discontinuum state a priori, discontinuous modeling techniques that are commonly referred to as discrete element methods (DEM) treat the material directly as an assembly of separate blocks or particles, which was originally proposed by Cundall (1971) and Cundall and Strack (1979) from the viewpoint of analogous molecular dynamics simulation to better account for and understand the interaction between the blocks. The distinct feature of these formulations is that a constantly changing problem of geometry and contact conditions can be addressed by solving the equations of motion using an explicit time marching scheme (most often in a ‘leap-frog’ format), while updating contact force histories as a consequence of contacts between different discrete elements and/or resulting from contacts with model boundaries (Bicanic 1998). The most notable implementations of DEMs are arguably represented by the universal distinct element code (UDEC) (Itasca Consulting Group Inc., 2013) and the particle flow code (PFC) (Itasca Consulting Group Inc., 2012). Another formulation is the discrete crack framework that is based upon some criteria for an advancement of crack front, which is coupled with extensive local and global re-meshing while simulating by numerical methods such as finite element technique, commonly using fracture theories. Certainly, it is relatively easy to trace the propagation of single crack front governed by some principles of energy release rates (Ingraffea 1997) but tracing of multiple cracks leads to topological and algorithmic complexities. Otherwise, there is no consideration of interacting cracks in these formulations of finite element or enhanced finite element techniques (e.g., in XFEM and ABAQUS)."

Jan 1, 2015

By L. O. Thomas

BROADLY, Yukon is divisible into three physiographic provinces which are extensions of the similar divisions in British Columbia that are there known as the Coastal system, the Interior system, and the Rocky Mountain system. South of Yukon to about the 50th parallel of latitude, the Coastal system consists solely of the Coast range, which, in Yukon, passes behind the St. Elias range and for the remainder of its course constitutes the most easterly portion of the Coastal system. The extension, in Yukon, of the Interior system of plateaus and mountains of British Columbia is commonly referred to as the Yukon plateau, and the extension of the Rocky Mountain system as the Mackenzie Mountains system. The Coast-Range province is largely made up of granitic intrusives; the Mackenzie Mountains province of folded sediments; and the intervening Yukon Plateau province of ancient metamorphic rocks, folded sedimentary rocks, volcanics, and intrusives. Almost the entire area dealt with in this article was subjected to glaciation and, in those parts where its full effect was experienced, the valleys were invaded by vast masses of ice which transported and scattered the stream gravels, with their gold content, so that, even where gold still remains in the old stream channels, it has become so buried under boulder clay and other glacial accumulations that it is, in most places, difficult to find, and, when found, may prove very expensive to mine. Most of the present rivers have done little more than cut new channels in the glacial debris, touching only here and there upon the subjacent rocky floor. The territory in Yukon adjacent to the section of the Alaska highway between Watson and Teslin lakes is for the most part unknown both topographically and geologically. From Teslin to Kluane, the highway travels a fairly well-mapped part of Yukon, but beyond that point, until White river is reached, the geology of the adjacent country has, largely, yet to be determined, particularly on the north side of the highway.

Jan 1, 1943

By K. J. Heale, G. G. Richards, D. J. Rioux, R. L. Stephens

Slag fuming has remained a key process for the recovery of Zn, Pb, and minor elements in the integrated flow sheet at Teck Cominco&apos;s Trail Operations for more than 75 years. Since the start-up of the KIVCETTM process and the #3 slag fuming furnace in 1997, a range of process intensification projects have been completed to improve metals recoveries and throughput based on improved process control, mechanical modifications, and, most recently, the implementation of oxygen enrichment of the blast air. This latter project, initially named &apos;nitrogen depletion&apos; and now &apos;nitrogen oxygen performance enhancement&apos; (NOPE), is the primary focus of this paper. NOPE reduces the amount of heat required to heat the inert nitrogen gas, and therefore more of the energy input can be used for reduction. It also frees up boiler capacity because the inert nitrogen gas does not then have to be cooled down. A dynamic METSIMTM model was developed to determine the opportunities to improve the process capacity and heat balance to both assist with justifying the project and to verify the observed furnace behaviour. Several process safety management issues were also addressed and a few key minor mechanical modifications were made to allow the project to proceed to commercial implementation at 25% blast air oxygen enrichment. Short term plant trials have confirmed the model predictions. The first three months of a long term, continuous trial showed a 6% increase in zinc fuming rate from average furnace performance despite the implementation of a KIVCETTM fluxing change to assist with minor element recovery that was expected to negatively impact the zinc fuming rate by 3 to 5%. This encouraging result is also in line with the model predictions.

Jan 1, 2008

By L. D. van Dyk, G. S. Tshofu

Iron ore fines are by-products of iron ore mining operations. Unlike iron ore lumps, fines cannot directly be used in conventional iron making processes, and consequently large quantities accumulate around the world. Pelletizing and sintering can be used to convert iron ore fines into agglomerates or briquettes for processing with lump ore, but these techniques are energy intensive and produce greenhouse gases. This research investigated the extraction of iron from iron ore fines using acetylacetone (a ß-diketone) as an environmentally friendly alternative process for fines utilization. A 2k factorial experiment design was used to identify the significant extraction variables. It was found that the reaction temperature and solid to liquid ratio had significant effects on the extraction process. The extraction kinetics were studied at different temperatures and the highest iron extraction (97 %) was obtained after 48 hours at 413 K and 0.025:1 (g:mL) solid to liquid ratio for a particle size range of +106 to -150 µm. The extraction products were easily separated from the unreacted acetylacetone by flash distillation and iron(III) acetylacetonate crystals were recovered. An economic evaluation showed that selling the crystals was profitable. Alternatively, the crystals can be reduced with hydrogen to iron particles and acetylacetone (for reuse).

Jan 1, 2015

By T. T. Ni

FOR MORE THAN 200 years, the Kochiu district of Yunnan province has been, and it still is, the hub of China&apos;s tin industry. The district produces annually from 80 to 90 per cent of that country&apos;s out-put of tin, which averages about 9,300 tons a year and places China fifth among the tin producing nations of the world. The tin ore reserves of the country are estimated (1) at 1,873,370 metric tons, of which 1,500,000 tons are in the Kochiu district. The mill of the Yunnan Consolidated Tin Corporation, described in this paper, is the only one of its kind in China. MINING AND SMELTING There are only two tin mines in the Kochiu district operating with modern equipment -the Hsin-Chang and the Lao-Chang, both owned by the Yunnan Consolidated Tin Corporation, a government company. The Hsin-Chang mine has four working levels with cross-cuts 6 ft. by 6 ft. and is equipped with steel mine cars and trucks to haul the ore. The ore is hoisted to surface in a three-compartment shaft and transferred to the mill by a 4-kilometer aerial tram. The Lao-Chang mine has two circular shafts 656 feet apart, each equipped with two cages. Haulage-ways 1,600 meters and 1,000 meters long, respectively, have been driven to the southwest from these shafts and are connected by three cross-cuts.

Jan 1, 1951

By Adrian Dance

The Antamina orebody is a geologically complex, polymetallic skarn located in the Peruvian Andes. A range of copper and copper-zinc ores are campaigned separately through the concentrator producing copper and zinc concentrates as well as lead and molybdenum by-products. Ore type classification at Antamina is based on chemical assays; geological or lithological variations are not considered. Consequently, each ore type demonstrates a wide range of concentrator performance. Antamina is currently implementing a system to track ore movements from the shovel face to the concentrator. Relatively sophisticated models of the ROM and coarse ore stockpiles ahead of the mill will be used to account for the variable delay between mining and milling. One of the numerous benefits of ore tracking is the ability to directly associate the measured concentrator performance with a physical location in the orebody. Using existing mine planning software, three-dimensional models can be created of such performance measures as metal recovery, concentrate quality, operating cost and reagent consumption. Such a database of information allows the true value of different ore sources to be determined. The value of an ore source is conventionally measured as metal content (individual or combined ?equivalent?) with a cut-off grade applied to indicate some base level operating cost. However, the true value of an ore source should include dynamic factors like haulage cost, reagent use, smelter penalties and even prevailing metal prices. If an ore source is considered from all perspectives rather than simply its potential to deliver value, the concept of ?ore? becomes more flexible. Any ore source that reveals itself to be unprofitable can be eliminated from the mine plan or possibly blended with others to improve its value. The ability to predict mill performance ? and thereby profitability ? is a powerful tool. In an operation such as Antamina, where managing ore sources, campaigns and the delivery of a variety of concentrates in a narrow timeline to customers is a daily challenge, prediction is the key to success and improved efficiency.

May 1, 2003

By William B. Coker, Vladimir J. Sopuck, J. S. Fox

"Preliminary investigations indicate that organic lake sediments offer some potential for gold exploration within the Canadian Shield of northwestern Saskatchewan. It is also apparent that certain precautions must be taken.Gold is primarily related to the organic fraction of the lake sediments, which, although giving consistant Au contents to those sediments, may restrict the dispersion of Au within the lake itself. It may be necessary to carry out selective extractions on the lake sediments to differentiate between Au related to organic sequestration, indicative of hydromorphic and/ or chemical dispersion, and Au related to inorganics, indicative of mechanical dispersion.Lake sediments are probably only of use for very detailed exploration (i.e. every lake). One to three samples per lake should be appropriate, although a single centre-lake organic-rich sediment sample may be adequate in very small lakes. Each lake sediment sample should be analyzed at least twice and the analytical data carefully monitored and evaluated.The use of As in lake sediments as a pathfinder element for gold is applicable in the search for certain types of gold occurrences.Following detailed lake sediment sampling, basal till sampling can possibly be used to localize areas of potential gold with or without base metal mineralization."

Jan 1, 1982

By Fazel G. Jahromi, Ahmad Ghahremaninezhad

Enargite (Cu3AsS4) is a major complex copper mineral and often is a carrier of invisible gold particles. Pyrometallurgical treatment of enargite is challenging due to the arsenic release to the environment. Hydrometallurgical treatment, on the other hand, appears to be a promising alternative for enargite processing. In an atmospheric enargite leaching process both the copper and arsenic from the mineral can be leached into a sulphuric acid solution and the arsenic can be simultaneously precipitated as ferric arsenate. The unlocked gold in the residue then can be recovered in a subsequent cyanidation circuit. The downside of the atmospheric enargite leaching in sulphate solutions is the slow leaching kinetics. In this study the effective parameters of the atmospheric enargite leaching process in ferric chloride media were investigated. All the experiments were carried out at temperatures below 100 °C. The process parameters that were investigated in this study included ferric, chloride, sulphate and cuprous concentrations, temperature, mixing rate and leaching slurry pulp density. It was found that the copper recovery rate increases with the addition of cupric chloride and also with raising the temperature. The highest leaching kinetics and the highest overall copper recoveries were achieved when cupric was initially added to the leach solution and at 90 ºC.

Jan 1, 2015