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A new process developed for the production of base metals Ni, Co and Fe, based on chloride hydrometallurgy, is applicable to both high- and low-iron laterite ores. The process comprises atmospheric leaching in mixed HCl-MgCl2 media to bring Fe, Ni, Co and Mg into solution, solvent-extraction steps to generate high-purity pregnant stripping solutions of Fe, Ni and Co individually, precipitation of high-purity Ni and Co products by addition of MgO generated from pyrohydrolysis, production of Fe2O3 and regeneration of HCl by pyrohydrolysis of the iron chloride-rich pregnant stripping solution, production of MgO and regeneration of HCl by pyrohydrolysis of bleed stream from the MgCl2-containing raffinate from the nickel sovent-extraction stage, and recycling of the HCl generated by pyrohydrolysis. A comparison of this process with commercial laterite processes - Caron process, high-pressure acid-leach process and pyrometallurgical process - is additionally presented., A new process developed for the production of base metals Ni, Co and Fe, based on chloride hydrometallurgy, is applicable to both high- and low-iron laterite ores. The process comprises atmospheric leaching in mixed HCl-MgCl2 media to bring Fe, Ni, Co and Mg into solution, solvent-extraction steps to generate high-purity pregnant stripping solutions of Fe, Ni and Co individually, precipitation of high-purity Ni and Co products by addition of MgO generated from pyrohydrolysis, production of Fe2O3 and regeneration of HCl by pyrohydrolysis of the iron chloride-rich pregnant stripping solution, production of MgO and regeneration of HCl by pyrohydrolysis of bleed stream from the MgCl2-containing raffinate from the nickel sovent-extraction stage, and recycling of the HCl generated by pyrohydrolysis. A comparison of this process with commercial laterite processes - Caron process, high-pressure acid-leach process and pyrometallurgical process - is additionally presented.

Nickel and cobalt can be recovered of from laterite ores by selective reduction of Ni and Co in preference to Fe followed by leaching in HCl-MgCl2 media. Ni, Co, Fe and Cu can also be extracted from sulphide ores by leaching of the concentrates at 90-100 degrees C in a recycled HCl-MgCl2 mixture with chlorine as an oxidant, with PGE recovered during a second-stage leach using established separation technologies. A process for the extraction of high-purity TiO2 from ilmenite ores, currently being tested at pilot scale, includes the leaching of ore/concentrate in HCl-MgCl2 lixiviant and three solvent-extraction stages: Fe removal, Ti extraction and V/Cr extraction., Nickel and cobalt can be recovered of from laterite ores by selective reduction of Ni and Co in preference to Fe followed by leaching in HCl-MgCl2 media. Ni, Co, Fe and Cu can also be extracted from sulphide ores by leaching of the concentrates at 90-100 degrees C in a recycled HCl-MgCl2 mixture with chlorine as an oxidant, with PGE recovered during a second-stage leach using established separation technologies. A process for the extraction of high-purity TiO2 from ilmenite ores, currently being tested at pilot scale, includes the leaching of ore/concentrate in HCl-MgCl2 lixiviant and three solvent-extraction stages: Fe removal, Ti extraction and V/Cr extraction.

A process is described which has been developed by Process Research Ortech, Ontario, Canada, which involves the atmospheric leaching of ilmenite ore to bring Fe, Ti and V into solution. After solid/liquid separation the pregnant liquor is subjected to stage 1 solvent extraction to remove Fe. Pregnant strip solution from stage one solvent extraction can be subjected to pyrolysis for the production of Fe oxide and the regeneration of acid for recycling. The raffinate undergoes stage 2 solvent extraction to recover Ti and the pregnant strip is subjected to thermal hydrolysis for TiO2 precipitation and the raffinate undergoes stage 3 solvent extraction to recover V. Tests were carried out on an ilmenite ore containing 22.8 wt% Ti, 38 wt% Fe, 0.13 wt% Cr2O3, 4.69 wt% SiO2 and 2.82 wt% MgO using a solution of HCl and MgCl2 under atmospheric pressure at 70-73 degrees C for 4 h. With increasing MgCl2 concentrations Ti extraction reached maximum levels of 79% and 96.9%, respectively, at HCl levels 1.2 and 1.4 times the stoichiometric amount required to extract Ti and Fe. The mixed chloride lixiviant provides high recovery, allows recycling of HCl and MgCl2 and enables a reduction in HCl concentration which allows azeotropic distillation by the pyrolysis of recycle solutions without the addition of substantial amounts of concentrated HCl. Aliquat 336, Cyanex 923, D2EHPA and LIX 622 were evaluated for the extraction of Ti from the Fe solvent extraction raffinate and Aliquat 336 and Cyanex 923 for the recovery of V from the Ti solvent extraction raffinate., A process is described which has been developed by Process Research Ortech, Ontario, Canada, which involves the atmospheric leaching of ilmenite ore to bring Fe, Ti and V into solution. After solid/liquid separation the pregnant liquor is subjected to stage 1 solvent extraction to remove Fe. Pregnant strip solution from stage one solvent extraction can be subjected to pyrolysis for the production of Fe oxide and the regeneration of acid for recycling. The raffinate undergoes stage 2 solvent extraction to recover Ti and the pregnant strip is subjected to thermal hydrolysis for TiO2 precipitation and the raffinate undergoes stage 3 solvent extraction to recover V. Tests were carried out on an ilmenite ore containing 22.8 wt% Ti, 38 wt% Fe, 0.13 wt% Cr2O3, 4.69 wt% SiO2 and 2.82 wt% MgO using a solution of HCl and MgCl2 under atmospheric pressure at 70-73 degrees C for 4 h. With increasing MgCl2 concentrations Ti extraction reached maximum levels of 79% and 96.9%, respectively, at HCl levels 1.2 and 1.4 times the stoichiometric amount required to extract Ti and Fe. The mixed chloride lixiviant provides high recovery, allows recycling of HCl and MgCl2 and enables a reduction in HCl concentration which allows azeotropic distillation by the pyrolysis of recycle solutions without the addition of substantial amounts of concentrated HCl. Aliquat 336, Cyanex 923, D2EHPA and LIX 622 were evaluated for the extraction of Ti from the Fe solvent extraction raffinate and Aliquat 336 and Cyanex 923 for the recovery of V from the Ti solvent extraction raffinate.

Process Research ORTECH has developed a mixed chloride leaching process for the recovery of titanium from ilmenite. After atmospheric leaching using a hydrochloric acid-magnesium chloride leach solution at 70-73 degrees C for 4 hours, the iron impurity is first removed by solvent extraction followed by a second solvent extraction stage to recover the Ti. The barren solution is used for reagent recovery and the regenerated leach liquor is recycled. Ti recoveries are as high as 96.9%. The results of laboratory and pilot-scale tests are presented., Process Research ORTECH has developed a mixed chloride leaching process for the recovery of titanium from ilmenite. After atmospheric leaching using a hydrochloric acid-magnesium chloride leach solution at 70-73 degrees C for 4 hours, the iron impurity is first removed by solvent extraction followed by a second solvent extraction stage to recover the Ti. The barren solution is used for reagent recovery and the regenerated leach liquor is recycled. Ti recoveries are as high as 96.9%. The results of laboratory and pilot-scale tests are presented.

Process Research ORTECH has developed a mixed chloride hydrometallurgical process for the recovery of base and precious metals from sulphide concentrates. Base metals were first extracted from the concentrates at 90-100 degrees C using a recycled MgCl2/HCl mixture with Cl2 as an oxidant, with extraction rates of 98% of Ni, 98% of Fe, 96% of Co and 98% of Cu. In the second stage, over 99% of Pt and Pd were recovered. Some of the advantages of the process are the recovery of elemental sulphur from sulphide sulphur, the recycling of the chloride lixiviant eliminating effluent treatment and use of excess energy from the Claus reactor for the pyrohydrolysis step., Process Research ORTECH has developed a mixed chloride hydrometallurgical process for the recovery of base and precious metals from sulphide concentrates. Base metals were first extracted from the concentrates at 90-100 degrees C using a recycled MgCl2/HCl mixture with Cl2 as an oxidant, with extraction rates of 98% of Ni, 98% of Fe, 96% of Co and 98% of Cu. In the second stage, over 99% of Pt and Pd were recovered. Some of the advantages of the process are the recovery of elemental sulphur from sulphide sulphur, the recycling of the chloride lixiviant eliminating effluent treatment and use of excess energy from the Claus reactor for the pyrohydrolysis step.

Past and present chloride processes used for the recovery of base and precious metals are reviewed. Brief details are given of date started, metals treated, leaching agents, metal recovery methods, largest-scale operations and, if applicable, the reason for discontinuing the process. Titanium dioxide processes, materials of construction and future developments are also covered., Past and present chloride processes used for the recovery of base and precious metals are reviewed. Brief details are given of date started, metals treated, leaching agents, metal recovery methods, largest-scale operations and, if applicable, the reason for discontinuing the process. Titanium dioxide processes, materials of construction and future developments are also covered.

One alternative to the high-pressure sulphuric acid leaching of high-iron limonitic nickel ores with more than35% Fe could be a selective-reduction mixed chloride leach. In the first stage the nickel is selectively reduced in preference to iron by the reducing gases formed by the combustion of fuel with sub-stoichiometric air, and this is followed by a HCl-MgCl2 leach. In laboratory tests 95% of nickel and cobalt was recovered. There is a higher metal recovery and lower acid consumption than in a similar process without the selective-reduction stage., One alternative to the high-pressure sulphuric acid leaching of high-iron limonitic nickel ores with more than35% Fe could be a selective-reduction mixed chloride leach. In the first stage the nickel is selectively reduced in preference to iron by the reducing gases formed by the combustion of fuel with sub-stoichiometric air, and this is followed by a HCl-MgCl2 leach. In laboratory tests 95% of nickel and cobalt was recovered. There is a higher metal recovery and lower acid consumption than in a similar process without the selective-reduction stage.

The paper reviews processes that are being commercialised or that are seriously under consideration for commercialisation. These include the Total Pressure Oxidation process, proven and expected to produce commercially in 2007, the CESL process, well tested at a 1 tonne/d cathode demonstration plant, and the Activox process, for which the first base metal refinery is planned to produce 20 000-25 000 t/a NI and 12 000- 16 000 t/a Cu from 2009. Other sulphate processes surveyed are the AAC/UBC process, bioleaching processes, the BIOCOP process, Bactech/Mintek process, GEOCOAT process, Dynatec process, Xstrata/Albion process, Mount Gordon copper process, nitrogen-species catalysed process, Sepon process and Galvanox technology; chloride-catalysed sulphate processes include, apart from CESL, the Noranda process, BHAS process and PLATSOL process. Four processes that use chloride solutions as lixiviants are the Intec, Outokumpu HydroCopper, Sumitomo and mixed chloride/JNI-PRO leach processes. Ammonia was used by the Arbiter process., The paper reviews processes that are being commercialised or that are seriously under consideration for commercialisation. These include the Total Pressure Oxidation process, proven and expected to produce commercially in 2007, the CESL process, well tested at a 1 tonne/d cathode demonstration plant, and the Activox process, for which the first base metal refinery is planned to produce 20 000-25 000 t/a NI and 12 000- 16 000 t/a Cu from 2009. Other sulphate processes surveyed are the AAC/UBC process, bioleaching processes, the BIOCOP process, Bactech/Mintek process, GEOCOAT process, Dynatec process, Xstrata/Albion process, Mount Gordon copper process, nitrogen-species catalysed process, Sepon process and Galvanox technology; chloride-catalysed sulphate processes include, apart from CESL, the Noranda process, BHAS process and PLATSOL process. Four processes that use chloride solutions as lixiviants are the Intec, Outokumpu HydroCopper, Sumitomo and mixed chloride/JNI-PRO leach processes. Ammonia was used by the Arbiter process.

A number of theoretical and basic chemical concepts concerning chloride brine chemistry are presented that have been borne out in batch laboratory tests of atmospheric leaching on laterites from Sechol in Guatemala. It has been clearly demonstrated that MgCl2/HCl brine leaching is an effective and efficient method of recovering nickel and cobalt from laterites. The degree of iron dissolution can be directly controlled in the leach circuit, such iron as dissolves being readily hydrolysed and precipitated so long as significant ferric chloro-anion complexes have not been formed. The use of magnesium chloride as the brine means that the amount of Mg leached can also be effectively managed. The circuit is relatively flexible, leaching being controlled by kinetic factors, total chloride and initial HCl concentrations, so that Ni, Co and/or magnesia recovery can be varied. The solids appear dehydrated, resulting in improved solid/liquid separation. Subsequent solution purification and recovery of mixed Ni/Co hydroxides is by standard precipitation methods using recycled caustic magnesia, with a final stage of pyrohydrolysis for recycling MgCl2 to caustic magnesia and chloride lixiviant., A number of theoretical and basic chemical concepts concerning chloride brine chemistry are presented that have been borne out in batch laboratory tests of atmospheric leaching on laterites from Sechol in Guatemala. It has been clearly demonstrated that MgCl2/HCl brine leaching is an effective and efficient method of recovering nickel and cobalt from laterites. The degree of iron dissolution can be directly controlled in the leach circuit, such iron as dissolves being readily hydrolysed and precipitated so long as significant ferric chloro-anion complexes have not been formed. The use of magnesium chloride as the brine means that the amount of Mg leached can also be effectively managed. The circuit is relatively flexible, leaching being controlled by kinetic factors, total chloride and initial HCl concentrations, so that Ni, Co and/or magnesia recovery can be varied. The solids appear dehydrated, resulting in improved solid/liquid separation. Subsequent solution purification and recovery of mixed Ni/Co hydroxides is by standard precipitation methods using recycled caustic magnesia, with a final stage of pyrohydrolysis for recycling MgCl2 to caustic magnesia and chloride lixiviant.

Fly ash obtained from processing tar sand was investigated and studies were also conducted on extracting V and Ni from orimulsion ash, or rendering the material inert for landfill disposal, and on recovering V, Co, Ni and Mo from spent catalysts. Secondary recovery from ash and catalysts was achieved using combinations of key unit operations such as flotation, roasting, leaching, ion exchange and precipitation. Routes included pressurised caustic leaching, caustic pug leaching, caustic agitation leaching, use of Dow G-55 ion exchange resins, acid leaching and roasting followed by bromine leaching. Key parameters such as reagent addition, temperature, pressure and pulp density were optimised and the production of chemical- and metallurgical-grade V2O5 from these secondary sources found feasible., Fly ash obtained from processing tar sand was investigated and studies were also conducted on extracting V and Ni from orimulsion ash, or rendering the material inert for landfill disposal, and on recovering V, Co, Ni and Mo from spent catalysts. Secondary recovery from ash and catalysts was achieved using combinations of key unit operations such as flotation, roasting, leaching, ion exchange and precipitation. Routes included pressurised caustic leaching, caustic pug leaching, caustic agitation leaching, use of Dow G-55 ion exchange resins, acid leaching and roasting followed by bromine leaching. Key parameters such as reagent addition, temperature, pressure and pulp density were optimised and the production of chemical- and metallurgical-grade V2O5 from these secondary sources found feasible.

Finely ground concentrates produced from complex ores are difficult to handle and process in conventional roasters. Experience with the TORBED reactor in the Cu and Ni industries suggests it would be suitable for Zn recovery from fine concentrates. A TORBED reactor has a compact shallow packed bed of particles suspended above an annular ring of stationary blades or vanes through which a process gas stream is passed at high velocity. Fine powders are injected into the reactor through the packed bed, allowing the powder to be flash roasted in 10-20 milliseconds. Use of such a technique for Zn sulphide concentrates produces significantly reduced ferrite formation and an order of magnitude increase in particle porosity, allowing faster leaching. TORBED reactors are often commercially viable at low throughputs and, for existing plants, the availability of these small-scale roasters may make it possible to consider calcination of residues from acid leaching., Finely ground concentrates produced from complex ores are difficult to handle and process in conventional roasters. Experience with the TORBED reactor in the Cu and Ni industries suggests it would be suitable for Zn recovery from fine concentrates. A TORBED reactor has a compact shallow packed bed of particles suspended above an annular ring of stationary blades or vanes through which a process gas stream is passed at high velocity. Fine powders are injected into the reactor through the packed bed, allowing the powder to be flash roasted in 10-20 milliseconds. Use of such a technique for Zn sulphide concentrates produces significantly reduced ferrite formation and an order of magnitude increase in particle porosity, allowing faster leaching. TORBED reactors are often commercially viable at low throughputs and, for existing plants, the availability of these small-scale roasters may make it possible to consider calcination of residues from acid leaching.

Preliminary screening testwork is reported on the potential usefulness of the n-alkyl hydroxamic acid group of metal chelating extractants, in particular n-ethyl-n-decano hydroxamic acid, for the selective extraction, purification and concentration of iron III from a zinc plant leach circuit. The potential application of hydroxamic acid solvent extraction technology in waste minimisation, impurity control and by-product iron recovery is briefly addressed., Preliminary screening testwork is reported on the potential usefulness of the n-alkyl hydroxamic acid group of metal chelating extractants, in particular n-ethyl-n-decano hydroxamic acid, for the selective extraction, purification and concentration of iron III from a zinc plant leach circuit. The potential application of hydroxamic acid solvent extraction technology in waste minimisation, impurity control and by-product iron recovery is briefly addressed.

The requirement for efficient, environmentally acceptable and economic removal of toxic and other metals will place increasing emphasis on adequate understanding of the treatment system. This system includes incoming process streams (aqueous or organic solutions, suspended particulate materials or colloids), equipment (such as contactors or liquid-solid separation units) and output streams (products and liquid or solid wastes) discharged to the local ecosystem. Those who develop flowsheets must have a much clearer knowledge of solution chemistry, its influence on the efficient removal of the desired metals and the effects of parameters such as pH, emf, concentration, nucleation, coprecipitation, temperature, organics and anion concentration. Seven illustrative case histories are selected from the nuclear, base metals and precious metals industries., The requirement for efficient, environmentally acceptable and economic removal of toxic and other metals will place increasing emphasis on adequate understanding of the treatment system. This system includes incoming process streams (aqueous or organic solutions, suspended particulate materials or colloids), equipment (such as contactors or liquid-solid separation units) and output streams (products and liquid or solid wastes) discharged to the local ecosystem. Those who develop flowsheets must have a much clearer knowledge of solution chemistry, its influence on the efficient removal of the desired metals and the effects of parameters such as pH, emf, concentration, nucleation, coprecipitation, temperature, organics and anion concentration. Seven illustrative case histories are selected from the nuclear, base metals and precious metals industries.

As the end of the millenium approaches, the global markets for the products of mining and metallurgy are changing at a rate unparalleled in history. Traditional markets are being driven to improve performance and reduce cost structures by international competition. Markets are emerging in advanced materials and high-value added products. A sustainable mining and metals industry will change if it is to survive. These changes will be accompanied by the implementation of novel technologies or the adoption of existing technologies in a more sophisticated fashion. This symposium focuses on the basic principles of those emerging technologies. Topics of discussion are future needs in the area of high value added and advanced material processing. Sessions include: Plenary, featuring trends and current processing techniques (3 papers); Mining on the moon (4 papers); Applications in mineral processing (4 papers); Role of hydrometallurgy in advanced materials (4 papers); Role of pyrometallurgy in advanced materials (5 papers); and Product characterisation and evaluation (6 papers)., As the end of the millenium approaches, the global markets for the products of mining and metallurgy are changing at a rate unparalleled in history. Traditional markets are being driven to improve performance and reduce cost structures by international competition. Markets are emerging in advanced materials and high-value added products. A sustainable mining and metals industry will change if it is to survive. These changes will be accompanied by the implementation of novel technologies or the adoption of existing technologies in a more sophisticated fashion. This symposium focuses on the basic principles of those emerging technologies. Topics of discussion are future needs in the area of high value added and advanced material processing. Sessions include: Plenary, featuring trends and current processing techniques (3 papers); Mining on the moon (4 papers); Applications in mineral processing (4 papers); Role of hydrometallurgy in advanced materials (4 papers); Role of pyrometallurgy in advanced materials (5 papers); and Product characterisation and evaluation (6 papers).

Compared to heap leaching, this continuous vat leaching method offers the following advantages: capital cost-competitive with heap leaching; can handle less than 0.25 inch material; lower water requirements; agglomeration not required; clays and precipitates can be handled; higher, faster recovery; can be protected from the elements at low cost; large, flat areas not required; free gold may not be lost; higher inherent oxygen diffusion; integral tails washing; and stackable tails possible. The Mackie Vat Leaching system represents a breakthrough in leaching technology, particularly as applied to the environment. The ability to contain leach activities and stack clean tailings could relieve the industry of many ills. In addition, low grade ore bodies in difficult climates or locales can benefit from this concept., Compared to heap leaching, this continuous vat leaching method offers the following advantages: capital cost-competitive with heap leaching; can handle less than 0.25 inch material; lower water requirements; agglomeration not required; clays and precipitates can be handled; higher, faster recovery; can be protected from the elements at low cost; large, flat areas not required; free gold may not be lost; higher inherent oxygen diffusion; integral tails washing; and stackable tails possible. The Mackie Vat Leaching system represents a breakthrough in leaching technology, particularly as applied to the environment. The ability to contain leach activities and stack clean tailings could relieve the industry of many ills. In addition, low grade ore bodies in difficult climates or locales can benefit from this concept.

Current research and process development activities on the application of ion exchange technique for gold industry indicate the potential application to recover gold from pregnant leach solution and its use to remove base metal cyano complexes from process effluents for barren recycle., Current research and process development activities on the application of ion exchange technique for gold industry indicate the potential application to recover gold from pregnant leach solution and its use to remove base metal cyano complexes from process effluents for barren recycle.

The development of a flowsheet to recover PGMs and construction of a prototype plant to treat up to 5 t/d feed material are described., The development of a flowsheet to recover PGMs and construction of a prototype plant to treat up to 5 t/d feed material are described.

An evaluation of refractory ores based on their physical or chemical refractory nature is made. Current practices and potential pretreatment alternatives including roasting, pressure leaching and atmospheric leaching methods to treat gold concentrates are assessed., An evaluation of refractory ores based on their physical or chemical refractory nature is made. Current practices and potential pretreatment alternatives including roasting, pressure leaching and atmospheric leaching methods to treat gold concentrates are assessed.

Test results and proposed pilot plant activity of Platinum Lake Technology Inc.'s proprietory chloride-organic leach process CRO/REDOX are described., Test results and proposed pilot plant activity of Platinum Lake Technology Inc.'s proprietory chloride-organic leach process CRO/REDOX are described.

The papers are split into 6 sessions. The opening session presents an overview of tailings management in several areas of the mining industry. Acid mine drainage is discussed in the following two sessions, firstly, from the standpoint of management of acid mine drainage, followed by six papers covering a variety of treatment methods. In the fourth session, tailings placement is discussed, with technologies varying from tailings ponds to underground disposal. Treatment of cyanide-bearing effluents in the gold processing industry is the subject of four papers in the fifth session. The concluding session contains two papers which present results of major studies to compare predictive techniques for acid mine drainage., The papers are split into 6 sessions. The opening session presents an overview of tailings management in several areas of the mining industry. Acid mine drainage is discussed in the following two sessions, firstly, from the standpoint of management of acid mine drainage, followed by six papers covering a variety of treatment methods. In the fourth session, tailings placement is discussed, with technologies varying from tailings ponds to underground disposal. Treatment of cyanide-bearing effluents in the gold processing industry is the subject of four papers in the fifth session. The concluding session contains two papers which present results of major studies to compare predictive techniques for acid mine drainage.

The Midwest orebody contains a high-arsenic uranium ore in a series of flat lenses overlain by a halo of lower-grade sandstone ore. At the processing plant, the ore undergoes grinding, leaching, solvent extraction and uranium precipitation and washing. The tailings and precipitates are neutralised and discharged to the tailings dumps at an average of 30% solids., The Midwest orebody contains a high-arsenic uranium ore in a series of flat lenses overlain by a halo of lower-grade sandstone ore. At the processing plant, the ore undergoes grinding, leaching, solvent extraction and uranium precipitation and washing. The tailings and precipitates are neutralised and discharged to the tailings dumps at an average of 30% solids.

Orrwell Energy's approach to production of crystalline flake graphite involves the use of autogenous grinding to liberate the graphite flake from the host rock and minimise flake deterioration. Development of the flowsheet, which incorporates autogenous milling, flotation a tabling circuit and a secondary regrind and flotation circuit, and pilot plant testing and full scale mill design are discussed. Capital and operating costs to install and operate a 500 t/day plant at Mount Laurier are derived., Orrwell Energy's approach to production of crystalline flake graphite involves the use of autogenous grinding to liberate the graphite flake from the host rock and minimise flake deterioration. Development of the flowsheet, which incorporates autogenous milling, flotation a tabling circuit and a secondary regrind and flotation circuit, and pilot plant testing and full scale mill design are discussed. Capital and operating costs to install and operate a 500 t/day plant at Mount Laurier are derived.

This paper describes the conceptual design of a system for a mining operation in the Northwest Territories of Canada. The design includes the concept of continuous countercurrent leaching in enclosed ore heaps. Indicative capital and operating costs are given., This paper describes the conceptual design of a system for a mining operation in the Northwest Territories of Canada. The design includes the concept of continuous countercurrent leaching in enclosed ore heaps. Indicative capital and operating costs are given.

The development of an inexpensive growth medium for the uranium-adsorbing fungus Rhizopus arrhizus is important in the production of large quantities of biomass. Fourteen industrial-based food processing wastes were obtained from various sources in southern Ontario. Carbon, nitrogen and phosphorus were determined for each sample and then prepared to concentration, which would theoretically maximise growth to 20 to 25 g biomass per litre of medium. Screening tests resulted in brewery grain-based waste media being selected for further growth optimisation., The development of an inexpensive growth medium for the uranium-adsorbing fungus Rhizopus arrhizus is important in the production of large quantities of biomass. Fourteen industrial-based food processing wastes were obtained from various sources in southern Ontario. Carbon, nitrogen and phosphorus were determined for each sample and then prepared to concentration, which would theoretically maximise growth to 20 to 25 g biomass per litre of medium. Screening tests resulted in brewery grain-based waste media being selected for further growth optimisation.

The production of platinum, palladium and rhodium salts from spent autocatalysts was found to feasible using chloride media. The catalysts were pretreated with sodium borate and caustic solutions near their boiling points and were then subjected to leaching in the presence of 65 kg/t NaCl, 30 kg/t NaClO2 and 250 l/t 37% HCl at 85 degrees C for 3 h. Recoveries were 89% of Pt and 95% of Pd. The leach liquors then underwent solvent extraction and precipitation of Pt and Pd salts. The solution rich in titanium chlorides was then hydrolysed with Ca or Mg materials to precipitate titanium oxyhydrate, which was then converted to TiO2 by calcining at elevated temperatures of 700-1 000 degrees C in the presence of air or oxygen. The extraction of titanium tetrachloride on the organic was also considered. Two case studies are presented., The production of platinum, palladium and rhodium salts from spent autocatalysts was found to feasible using chloride media. The catalysts were pretreated with sodium borate and caustic solutions near their boiling points and were then subjected to leaching in the presence of 65 kg/t NaCl, 30 kg/t NaClO2 and 250 l/t 37% HCl at 85 degrees C for 3 h. Recoveries were 89% of Pt and 95% of Pd. The leach liquors then underwent solvent extraction and precipitation of Pt and Pd salts. The solution rich in titanium chlorides was then hydrolysed with Ca or Mg materials to precipitate titanium oxyhydrate, which was then converted to TiO2 by calcining at elevated temperatures of 700-1 000 degrees C in the presence of air or oxygen. The extraction of titanium tetrachloride on the organic was also considered. Two case studies are presented.

Typical industrial sulphide concentrates were used to establish conditions for effective roasting at high temperature using a toroidal fluidised-bed or Torbed reactor. A sticky layer obtained from the pilot reactor during roasting of copper concentrates was characterised by X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray analysis. The stickiness was attributed to liquid-phase sintering, a conclusion consistent with information derived from the relevant phase diagrams. Sintering and ferrite formation were further studied using an electric tube furnace under controlled roasting conditions. Oxygen concentrations near those of air played an important role in promoting roasting, whereas temperatures higher than 950 degrees C sintered sulphide particles and inhibited the diffusion of O2 into particle cores. Roasting in the Torbed reactor increased the surface area of the zinc calcine and reduced the formation of zinc ferrite, improving Zn recovery by acid leaching., Typical industrial sulphide concentrates were used to establish conditions for effective roasting at high temperature using a toroidal fluidised-bed or Torbed reactor. A sticky layer obtained from the pilot reactor during roasting of copper concentrates was characterised by X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray analysis. The stickiness was attributed to liquid-phase sintering, a conclusion consistent with information derived from the relevant phase diagrams. Sintering and ferrite formation were further studied using an electric tube furnace under controlled roasting conditions. Oxygen concentrations near those of air played an important role in promoting roasting, whereas temperatures higher than 950 degrees C sintered sulphide particles and inhibited the diffusion of O2 into particle cores. Roasting in the Torbed reactor increased the surface area of the zinc calcine and reduced the formation of zinc ferrite, improving Zn recovery by acid leaching.

The Kapuskasing operation in Ontario mines and processes up to 6 000 t/d of sandy or cemented phosphate ore by run-of-mine crushing to smaller than 6 inches in a toothed roll-crusher and grinding in a SAG/ball mill circuit with no coarse recycle classification of the SAG mill discharge. It was found that when hard ore was treated the SAG mill restricted the tonnage that could be ground while when soft ore was treated the ball mill and spiral classifier were overloaded. Recommendations from a benchmarking and hardness testing programme were checked in a pilot-plant investigation. Correlation between tested hardness and the results from the 3-ft pilot SAG mill was very good. The work also indicated the results that could be expected for different ore types when using either smaller SAG discharge grates or a vibrating screen with 10-mesh square opening cloth., The Kapuskasing operation in Ontario mines and processes up to 6 000 t/d of sandy or cemented phosphate ore by run-of-mine crushing to smaller than 6 inches in a toothed roll-crusher and grinding in a SAG/ball mill circuit with no coarse recycle classification of the SAG mill discharge. It was found that when hard ore was treated the SAG mill restricted the tonnage that could be ground while when soft ore was treated the ball mill and spiral classifier were overloaded. Recommendations from a benchmarking and hardness testing programme were checked in a pilot-plant investigation. Correlation between tested hardness and the results from the 3-ft pilot SAG mill was very good. The work also indicated the results that could be expected for different ore types when using either smaller SAG discharge grates or a vibrating screen with 10-mesh square opening cloth.

Heap leaching, although much cheaper than conventional milling, depends for its success on factors as varied as climate, ore texture and land availability. The Mackie vat leaching jig would be similar to heap leaching in capital cost and save up to 10% of operating costs in terms of power alone. A typical Canadian ore would yield 80-85% metal recovery, as against 92-95% for milling and up to 70% for heap leaching even if operation were possible in winter. The concept involves a vat with a grid of drainage pipes at the bottom, a French drain of graded stone or mine waste over it and above that a second grid of pipes with openings to introduce lixiviant into the ore bed. Ore is fed in continuously as high-density slurry, but lixiviant only in short, high-volume bursts so that the ore bed alternately expands and thickens, dispersing the lixiviant evenly. Samples of up to 75 lb have been successfully tested in a 5.5 inch diameter column using samples crushed to -6 mesh, and a pilot plant for treating samples up to 20 t is planned., Heap leaching, although much cheaper than conventional milling, depends for its success on factors as varied as climate, ore texture and land availability. The Mackie vat leaching jig would be similar to heap leaching in capital cost and save up to 10% of operating costs in terms of power alone. A typical Canadian ore would yield 80-85% metal recovery, as against 92-95% for milling and up to 70% for heap leaching even if operation were possible in winter. The concept involves a vat with a grid of drainage pipes at the bottom, a French drain of graded stone or mine waste over it and above that a second grid of pipes with openings to introduce lixiviant into the ore bed. Ore is fed in continuously as high-density slurry, but lixiviant only in short, high-volume bursts so that the ore bed alternately expands and thickens, dispersing the lixiviant evenly. Samples of up to 75 lb have been successfully tested in a 5.5 inch diameter column using samples crushed to -6 mesh, and a pilot plant for treating samples up to 20 t is planned.

A simplified method to chemically modify the surface of industrial mineral fillers is described., A simplified method to chemically modify the surface of industrial mineral fillers is described.

Preliminary tests show that the Penicillium biomass can be converted to an immobilised form to provide uranium adsorption at up to 150mg/g dry biomass., Preliminary tests show that the Penicillium biomass can be converted to an immobilised form to provide uranium adsorption at up to 150mg/g dry biomass.

A unique atmospheric mixed chloride leaching process has been developed for the recovery of copper and nickel from sulphide concentrates. The process also produces by-products of high purity cobalt and iron oxide, and recycles chloride lixiviant to the leaching stage. Studies have been carried out of the leaching of sulphide concentrates with a lixiviant containing hydrochloric acid and magnesium chloride at atmospheric pressure at 90-95 degrees C. After solid-liquid separation, the pregnant leach solution was used in solvent extraction steps prior to selective separation of Fe followed by Cu, Co, and Ni. It was found that the addition of MgCl2 to HCl increased the activity of the hydrogen ion in the lixiviant, allowing a rapid leaching rate at modest temperatures and pressures with a lower concentration of HCl. The use of MgCl2 and LIX 63 in the lixiviant gave separation of Ni2+ at a lower pH (0.5-2.5). Other advantages included a reduction in reagent cost by regenerating and recycling HCl and minimising waste production by recycling the chloride lixiviant to the leaching stage. It is concluded the process could be a potential alternative to conventional hydrometallurgical and smelting processes by meeting more stringent environmental requirements and reducing capital and operating costs., A unique atmospheric mixed chloride leaching process has been developed for the recovery of copper and nickel from sulphide concentrates. The process also produces by-products of high purity cobalt and iron oxide, and recycles chloride lixiviant to the leaching stage. Studies have been carried out of the leaching of sulphide concentrates with a lixiviant containing hydrochloric acid and magnesium chloride at atmospheric pressure at 90-95 degrees C. After solid-liquid separation, the pregnant leach solution was used in solvent extraction steps prior to selective separation of Fe followed by Cu, Co, and Ni. It was found that the addition of MgCl2 to HCl increased the activity of the hydrogen ion in the lixiviant, allowing a rapid leaching rate at modest temperatures and pressures with a lower concentration of HCl. The use of MgCl2 and LIX 63 in the lixiviant gave separation of Ni2+ at a lower pH (0.5-2.5). Other advantages included a reduction in reagent cost by regenerating and recycling HCl and minimising waste production by recycling the chloride lixiviant to the leaching stage. It is concluded the process could be a potential alternative to conventional hydrometallurgical and smelting processes by meeting more stringent environmental requirements and reducing capital and operating costs.

A study is described in which the potential of biotechnology applications to metallurgical processing at Falconbridge Ltd. was evaluated. Following a survey of various Falconbridge environs for process potential microorganisms, the development of a nickel recovery program from the pyrrhotite-based tailings using autochthonous Thiobacilli was undertaken. Laboratory scale investigations revealed that Thiobacillus ferrooxidans consistently leaches higher percentages of nickel than a mixed culture containing T. thiooxidans while the presence of catalytic amounts of copper in the bioleach liquor not only caused reduced nickel recoveries but also resulted in lower acid consumption to maintain low pH values. Pulp densities as high as 20% to 30% had no deleterious effect on the leach values over 21 days but the use of acidic pretreated tailings had no dramatic effects on pH control or nickel leached. Bioconditioning the pyrrhotite tailings before a flotation treatment suggested, through limited test work, that long bioconditioning times offer little improvement over blank conditioning., A study is described in which the potential of biotechnology applications to metallurgical processing at Falconbridge Ltd. was evaluated. Following a survey of various Falconbridge environs for process potential microorganisms, the development of a nickel recovery program from the pyrrhotite-based tailings using autochthonous Thiobacilli was undertaken. Laboratory scale investigations revealed that Thiobacillus ferrooxidans consistently leaches higher percentages of nickel than a mixed culture containing T. thiooxidans while the presence of catalytic amounts of copper in the bioleach liquor not only caused reduced nickel recoveries but also resulted in lower acid consumption to maintain low pH values. Pulp densities as high as 20% to 30% had no deleterious effect on the leach values over 21 days but the use of acidic pretreated tailings had no dramatic effects on pH control or nickel leached. Bioconditioning the pyrrhotite tailings before a flotation treatment suggested, through limited test work, that long bioconditioning times offer little improvement over blank conditioning.

A study to test and optimise a new sol-gel formulation is described. The sol-gel is to be used in conjunction with the unproven industrial waste-grown uranium adsorbing fungus Rhizopus arrhizus. The testwork was undertaken on a bench scale in an attempt to simulate an ion exchange process on an industrial scale. The sol-gel formulation was optimised with respect to fungal form used, the addition of fines and the effect of preconditioning. Uranium loading and elution optimisation include particle sizing and the effect of flow rates. The U-uptake values were highest at 60 mg/g biomass and observed in stir tests using sol-gel composed of 50% comminution fines. The column tested sol-gel indicated a lifetime of at least 8 loading elution cycles which has the potential for an extended lifetime upon further optimisation., A study to test and optimise a new sol-gel formulation is described. The sol-gel is to be used in conjunction with the unproven industrial waste-grown uranium adsorbing fungus Rhizopus arrhizus. The testwork was undertaken on a bench scale in an attempt to simulate an ion exchange process on an industrial scale. The sol-gel formulation was optimised with respect to fungal form used, the addition of fines and the effect of preconditioning. Uranium loading and elution optimisation include particle sizing and the effect of flow rates. The U-uptake values were highest at 60 mg/g biomass and observed in stir tests using sol-gel composed of 50% comminution fines. The column tested sol-gel indicated a lifetime of at least 8 loading elution cycles which has the potential for an extended lifetime upon further optimisation.