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The future of zinc smelting processes largely depends on the cost of the energy required to run them. The pyrometallurgical process, including the vertical retort process, has more energy saving potential than the electrolytic process. The vertical retort process also has the capacity to treat some complex and recycled zinc materials more efficiently than hydrometallurgical processes. It is also possible to recover valuable impurities economically by suitable treatment of the zinc-cadmium alloy, blister lead and hard zinc produced as intermediates in the vertical retort process., The future of zinc smelting processes largely depends on the cost of the energy required to run them. The pyrometallurgical process, including the vertical retort process, has more energy saving potential than the electrolytic process. The vertical retort process also has the capacity to treat some complex and recycled zinc materials more efficiently than hydrometallurgical processes. It is also possible to recover valuable impurities economically by suitable treatment of the zinc-cadmium alloy, blister lead and hard zinc produced as intermediates in the vertical retort process.

Gallium and indium are recovered commercially from the zinc concentrates that the Iijima zinc refinery use to produce zinc and cadmium. They are concentrated in the mixture of hydroxides and gypsum formed during the residue treatment process. Gallium and indium are extracted with solvent after eliminating copper and arsenic. The pure metals are then produced by electrowinning. Many smelters recover gallium or indium, but few produce both metals., Gallium and indium are recovered commercially from the zinc concentrates that the Iijima zinc refinery use to produce zinc and cadmium. They are concentrated in the mixture of hydroxides and gypsum formed during the residue treatment process. Gallium and indium are extracted with solvent after eliminating copper and arsenic. The pure metals are then produced by electrowinning. Many smelters recover gallium or indium, but few produce both metals.

Recently developed copper extraction processes have been evaluated according to total energy requirements. The energy requirements are evaluated in terms of direct energy input and energy required for consumables. Both pyrometallurgical and hydrometallurgical processes are discussed. Processes common to most copper extraction operations such as mining, mineral processing, gas cleaning and sulphuric acid production are considered., Recently developed copper extraction processes have been evaluated according to total energy requirements. The energy requirements are evaluated in terms of direct energy input and energy required for consumables. Both pyrometallurgical and hydrometallurgical processes are discussed. Processes common to most copper extraction operations such as mining, mineral processing, gas cleaning and sulphuric acid production are considered.

The production of oil by surface mining and processing is economically and technically feasible at present oil prices. The production of oil by drainage methods from underground workings my also be economically viable in some cases. Some of the largest potential oil mining resources are in areas of limited environmental impact such as the Orinoco Basin and Utah. The amount of oil resources suitable for mining is not known, but there are many areas where mining development is both economically and technically feasible., The production of oil by surface mining and processing is economically and technically feasible at present oil prices. The production of oil by drainage methods from underground workings my also be economically viable in some cases. Some of the largest potential oil mining resources are in areas of limited environmental impact such as the Orinoco Basin and Utah. The amount of oil resources suitable for mining is not known, but there are many areas where mining development is both economically and technically feasible.

The ElectroSlurry process (ESP) employs a newly developed high current density cell which accomplishes leaching and electrowinning simultaneously with no oxygen overpotential. This process has shown 98% copper recovery from chalcopyrite concentrates. The energy requirements have been calculated to be competitive with pyrometallurgical processes while avoiding the environmental problems associated with smelting. Capital and direct operating costs are estimated to be $ 2420/annual tonne Cu for a 45 455 tonne/year production plant., The ElectroSlurry process (ESP) employs a newly developed high current density cell which accomplishes leaching and electrowinning simultaneously with no oxygen overpotential. This process has shown 98% copper recovery from chalcopyrite concentrates. The energy requirements have been calculated to be competitive with pyrometallurgical processes while avoiding the environmental problems associated with smelting. Capital and direct operating costs are estimated to be $ 2420/annual tonne Cu for a 45 455 tonne/year production plant.

Matsumine mill went into production in 1966 and now has a throughput of 40 000 tons of crude ore a month. The complex sulphide ore contains gold and silver, and also chalcopyrite, galena, sphalerite, pyrite and barite. The ore is characterised by a fine complex texture, easy oxidation and high primary slimes. The separation of the precious metals is extremely difficult, but good results have been obtained using a combination of sulphur dioxide flotation and hot water flotation, as well as by developing new conditions and control systems for flotation processes., Matsumine mill went into production in 1966 and now has a throughput of 40 000 tons of crude ore a month. The complex sulphide ore contains gold and silver, and also chalcopyrite, galena, sphalerite, pyrite and barite. The ore is characterised by a fine complex texture, easy oxidation and high primary slimes. The separation of the precious metals is extremely difficult, but good results have been obtained using a combination of sulphur dioxide flotation and hot water flotation, as well as by developing new conditions and control systems for flotation processes.

Hydrometallurgical processes for recovering As2O3 from As2S3 precipitate are thought to be more pollution free than others. Oxidative leaching is often used followed by the reduction of the As5+ ion and the crystallisation of As2O3. To avoid this complex process, solvent extraction using D2EHDTPA (di-2-ethylhexyldithiophosphoric acid) was examined. In this way the As3+ ion was easily extracted from the aqueous solution containing H2SO4. Back-extraction is feasible by using an alkaline aqueous solution containing Na2CO3., Hydrometallurgical processes for recovering As2O3 from As2S3 precipitate are thought to be more pollution free than others. Oxidative leaching is often used followed by the reduction of the As5+ ion and the crystallisation of As2O3. To avoid this complex process, solvent extraction using D2EHDTPA (di-2-ethylhexyldithiophosphoric acid) was examined. In this way the As3+ ion was easily extracted from the aqueous solution containing H2SO4. Back-extraction is feasible by using an alkaline aqueous solution containing Na2CO3.

Pollution problems have arisen from mining heavy metals such as cadmium, mercury and arsenic. In the 1960s pollution became a serious conern, and problems included the relationship between heavy metals and health and agriculture, the pollution of water even after mines have closed, and the responsibility for the problem if the owner of the disused mine is unknown or dead. Legislation to control these problems was passed in 1973. The Metal Mining Agency of Japan provides funds for metals exploitation, and also for pollution control., Pollution problems have arisen from mining heavy metals such as cadmium, mercury and arsenic. In the 1960s pollution became a serious conern, and problems included the relationship between heavy metals and health and agriculture, the pollution of water even after mines have closed, and the responsibility for the problem if the owner of the disused mine is unknown or dead. Legislation to control these problems was passed in 1973. The Metal Mining Agency of Japan provides funds for metals exploitation, and also for pollution control.

In the last two years the use of coal, higher oxygen enrichment smelting, and operation without oil burning have been developed in the Mitsubishi continuous copper smelting and converting process. The utilisation of coal has achieved stable operation with a longer life of the refractories. The higher oxygen-enrichment and smelting without oil burning are expected to bring about much better results in the future, both economic and metallurgic., In the last two years the use of coal, higher oxygen enrichment smelting, and operation without oil burning have been developed in the Mitsubishi continuous copper smelting and converting process. The utilisation of coal has achieved stable operation with a longer life of the refractories. The higher oxygen-enrichment and smelting without oil burning are expected to bring about much better results in the future, both economic and metallurgic.

The economic vitality of industrialised nations depends on their mineral values, particularly in some of the scarce elements. Increased demand on the limited mineral values makes it important to conserve these resources. Processing the minerals also causes certain environmental problems, so the ability to collect, extract, and control mineral values as they are processed must be the aim of mineral research. As scarce minerals become depleted, wider uses will have to be found for the more abundant materials., The economic vitality of industrialised nations depends on their mineral values, particularly in some of the scarce elements. Increased demand on the limited mineral values makes it important to conserve these resources. Processing the minerals also causes certain environmental problems, so the ability to collect, extract, and control mineral values as they are processed must be the aim of mineral research. As scarce minerals become depleted, wider uses will have to be found for the more abundant materials.

Different kinds of minerals are found in different marine environments: sulphur as a subsurface soluble mineral, placer deposits as a surficial deposit, iron ore as a sub-surface bedrock deposit, and salts from seawater. The economic potentials of minerals from the marine beach, continental shelf and slope, continental rise, small ocean basin, abyssal plain, and mid-oceanic ridge and rise environments are discussed. Materials which will be mined in the next few decades are large and high grade offshore deposits, metals and bulk materials in short supply, and manganese nodules., Different kinds of minerals are found in different marine environments: sulphur as a subsurface soluble mineral, placer deposits as a surficial deposit, iron ore as a sub-surface bedrock deposit, and salts from seawater. The economic potentials of minerals from the marine beach, continental shelf and slope, continental rise, small ocean basin, abyssal plain, and mid-oceanic ridge and rise environments are discussed. Materials which will be mined in the next few decades are large and high grade offshore deposits, metals and bulk materials in short supply, and manganese nodules.

The Toyo copper refinery has a production capacity of 4500 tons/month of electrolytic copper. The process is completely pollution free, and the most advanced electrolysis technology is used. The refinery has a spacious layout to enable further expansion, and has automated tankhouse equipment and materials handling machinery. The refinery has achieved a 20% reduction in energy costs over the last three years by thermally insulating the cell and using a unique cathode bar washing system. A high quality smooth copper is produced from an originally dirty copper concentrate., The Toyo copper refinery has a production capacity of 4500 tons/month of electrolytic copper. The process is completely pollution free, and the most advanced electrolysis technology is used. The refinery has a spacious layout to enable further expansion, and has automated tankhouse equipment and materials handling machinery. The refinery has achieved a 20% reduction in energy costs over the last three years by thermally insulating the cell and using a unique cathode bar washing system. A high quality smooth copper is produced from an originally dirty copper concentrate.

The Chigirishima smelter, Japan, produces 60 000 tonnes/year of electrolytic lead by updraft sintering, blast furnace, and electrolytic refining processes. The sintering plant is highly efficient (the operating time efficiency is 92.6%) and has good productivity. Automatic machinery has been introduced in the vertical type anode casting machine, in a prearrangement system of anode and starting and deposited lead., The Chigirishima smelter, Japan, produces 60 000 tonnes/year of electrolytic lead by updraft sintering, blast furnace, and electrolytic refining processes. The sintering plant is highly efficient (the operating time efficiency is 92.6%) and has good productivity. Automatic machinery has been introduced in the vertical type anode casting machine, in a prearrangement system of anode and starting and deposited lead.

The lead smelter at Takehara is designed to produce high purity electrolytic lead from secondary lead-bearing materials. Materials from secondary lead sources contain valuable metals, alkaline metals or halogens. In the smelting operation a blast furnace and two short rotary furnaces recover valuable metals and fix hazardous elements. The refining process produces high purity electrolytic lead. In the smelting or refining operation, gold, silver antimony, tin, tellurium, bismuth and indium are recovered as by-products., The lead smelter at Takehara is designed to produce high purity electrolytic lead from secondary lead-bearing materials. Materials from secondary lead sources contain valuable metals, alkaline metals or halogens. In the smelting operation a blast furnace and two short rotary furnaces recover valuable metals and fix hazardous elements. The refining process produces high purity electrolytic lead. In the smelting or refining operation, gold, silver antimony, tin, tellurium, bismuth and indium are recovered as by-products.

Electric smelting concentrates heat in the furnace bath and eliminates heat loss in large volumes of furnace off-gas, promotes solution of relatively high-melting speiss phases in the furnace matte and avoids crust formation on the bath. The fuel-fired furnace at Buick furnace in Missouri, was modified to an electric arc furnace after a cost study showed it would be economically advantageous. The power requirements increase as iron oxide content increases due to the decreased electrode penetration required., Electric smelting concentrates heat in the furnace bath and eliminates heat loss in large volumes of furnace off-gas, promotes solution of relatively high-melting speiss phases in the furnace matte and avoids crust formation on the bath. The fuel-fired furnace at Buick furnace in Missouri, was modified to an electric arc furnace after a cost study showed it would be economically advantageous. The power requirements increase as iron oxide content increases due to the decreased electrode penetration required.

Stability diagrams for iron (III) arsenate, calcium arsenate and magnesium arsenate show that the minimum solubility of these compounds is significantly higher than was thought. The presence of a low concentration of carbonate affects this minimum solubility greatly. This high solubility of metal arsenates leads to important considerations in relation to the disposal of arsenic-containing residues from metal extraction processes., Stability diagrams for iron (III) arsenate, calcium arsenate and magnesium arsenate show that the minimum solubility of these compounds is significantly higher than was thought. The presence of a low concentration of carbonate affects this minimum solubility greatly. This high solubility of metal arsenates leads to important considerations in relation to the disposal of arsenic-containing residues from metal extraction processes.

The whole mining area of the colliery is under the sea. To ensure adequate ventilation three man-made islands were built with shafts to the pit. In places, extremely high rock temperatures occur, and the coal bearing formations contain a lot of water so have a large thermal capacity. It was found that the origin of the heat was hot springs. To cool the underground environment water was drained from the Tertiary strata, hot air or water was shut out, and the cooling system was decentralised to the necessary places., The whole mining area of the colliery is under the sea. To ensure adequate ventilation three man-made islands were built with shafts to the pit. In places, extremely high rock temperatures occur, and the coal bearing formations contain a lot of water so have a large thermal capacity. It was found that the origin of the heat was hot springs. To cool the underground environment water was drained from the Tertiary strata, hot air or water was shut out, and the cooling system was decentralised to the necessary places.

Developments are described in the mining of coal, gold, copper, iron ore, manganese, mica and crude oil. To meet the challenge of increased production, safety and health conditions need to be improved. The major elements to be considered in the case of accident prevention are technology, legislation, safety education and training, and workers' participation. The main health hazards are pneumoconiosis in coal and gold mines, heat exhaustion, the disease manganism in manganese mines, and fatigue due to arduous working conditions., Developments are described in the mining of coal, gold, copper, iron ore, manganese, mica and crude oil. To meet the challenge of increased production, safety and health conditions need to be improved. The major elements to be considered in the case of accident prevention are technology, legislation, safety education and training, and workers' participation. The main health hazards are pneumoconiosis in coal and gold mines, heat exhaustion, the disease manganism in manganese mines, and fatigue due to arduous working conditions.

The challenges are discussed which are involved in exploration for bauxite, bauxite mining, refining bauxite to pure aluminium oxide, smelting aluminium oxide to aluminium, purifiying the metal, and casting it into solid form. It is important that the understanding of the extractive metallurgy of aluminium increases so that the metal can be produced more abundantly and economically. It is also important that new products be developed which can be recycled., The challenges are discussed which are involved in exploration for bauxite, bauxite mining, refining bauxite to pure aluminium oxide, smelting aluminium oxide to aluminium, purifiying the metal, and casting it into solid form. It is important that the understanding of the extractive metallurgy of aluminium increases so that the metal can be produced more abundantly and economically. It is also important that new products be developed which can be recycled.

Ores containing a significant amount of secondary copper minerals are unsatisfactorily treated by cyanides or bichromates, but cyanide-free and bichromate-free processes can be used. Flotation processes can be improved by the use of equi-flotation. Selective collectors are used to treat complex sulphide ores, including aerofloat of ammonium salt, SN-9 and PN-4. The principal flotation flowsheets, reagent regimes and separation performances of a number of concentrators are discussed., Ores containing a significant amount of secondary copper minerals are unsatisfactorily treated by cyanides or bichromates, but cyanide-free and bichromate-free processes can be used. Flotation processes can be improved by the use of equi-flotation. Selective collectors are used to treat complex sulphide ores, including aerofloat of ammonium salt, SN-9 and PN-4. The principal flotation flowsheets, reagent regimes and separation performances of a number of concentrators are discussed.

Zirconium dioxide is produced commercially by a new process based on high temperature plasma furnace technology. Zircon grains are injected into the 14 000 K flame where they melt and dissociate into ZrO2 and SiO2. The free falling grains are rapidly cooled. The silica is readily leached in caustic soda solution to form sodium metasilicate. The zirconium dioxide crystals are washed and further processed into grades suitable for commercial use. Zirconium dioxide grades of up to 99.9% can be produced. The process is consistent and easy to control with a minimum of environmental problems., Zirconium dioxide is produced commercially by a new process based on high temperature plasma furnace technology. Zircon grains are injected into the 14 000 K flame where they melt and dissociate into ZrO2 and SiO2. The free falling grains are rapidly cooled. The silica is readily leached in caustic soda solution to form sodium metasilicate. The zirconium dioxide crystals are washed and further processed into grades suitable for commercial use. Zirconium dioxide grades of up to 99.9% can be produced. The process is consistent and easy to control with a minimum of environmental problems.

A process using water vapour and lime has been developed for transforming metal sulphides to the corresponding oxides and other more leachable compounds. The water vapour oxidises the sulphide and the hydrogen sulphide produced is absorbed by lime to yield calcium sulphide and regenerate water vapour. There is no net consumption or generation of gaseous species, so the process can be carried out in a closed system. The scheme is possible only for certain metal sulphides for which the free energy of overall reaction is negative. Sulphides of molybdenum and zinc have sucessfully been treated by this method., A process using water vapour and lime has been developed for transforming metal sulphides to the corresponding oxides and other more leachable compounds. The water vapour oxidises the sulphide and the hydrogen sulphide produced is absorbed by lime to yield calcium sulphide and regenerate water vapour. There is no net consumption or generation of gaseous species, so the process can be carried out in a closed system. The scheme is possible only for certain metal sulphides for which the free energy of overall reaction is negative. Sulphides of molybdenum and zinc have sucessfully been treated by this method.

The reverberatory furnace converter operation in the copper smelting industry has some drawbacks in SO2 pollution control, one of which is the difficulty in preventing leakage of SO2 gases. Many attempts have been made to collect fugitive gases from the Onahama smelter process. Modification and expansion work was completed in 1978. The new fugitive gas treatment system has brought about a substantial decrease of SO2 emission from the smelter. Approximately 99.7% of input sulphur is now recovered or fixed., The reverberatory furnace converter operation in the copper smelting industry has some drawbacks in SO2 pollution control, one of which is the difficulty in preventing leakage of SO2 gases. Many attempts have been made to collect fugitive gases from the Onahama smelter process. Modification and expansion work was completed in 1978. The new fugitive gas treatment system has brought about a substantial decrease of SO2 emission from the smelter. Approximately 99.7% of input sulphur is now recovered or fixed.

High gradient magnetic separation (HGMS) for the fine treatment of industrial sludges was studied with several simulated ores. The sludges were made of chemical reagents of ..-Fe2O3, Cr(OH)3 and SiO2. The samples were prepared in a slurry and tested both separately and in a mixture. Separation tests of a paramagnetic or weakly magnetic ..-Fe2O3 from a diamagnetic SiO2 were successful and had a separation efficiency of over 90%., High gradient magnetic separation (HGMS) for the fine treatment of industrial sludges was studied with several simulated ores. The sludges were made of chemical reagents of ..-Fe2O3, Cr(OH)3 and SiO2. The samples were prepared in a slurry and tested both separately and in a mixture. Separation tests of a paramagnetic or weakly magnetic ..-Fe2O3 from a diamagnetic SiO2 were successful and had a separation efficiency of over 90%.

The pollution problem is more severe in Japan than other countries because of its high population density, the variety of ores and pollution problems that exist, and water quality is very important as the country is wet and grows rice. Environmental control techniques for mines used in Japan consist of mine plugging or sealing, mine water treatment, and surface treatment and reclamation., The pollution problem is more severe in Japan than other countries because of its high population density, the variety of ores and pollution problems that exist, and water quality is very important as the country is wet and grows rice. Environmental control techniques for mines used in Japan consist of mine plugging or sealing, mine water treatment, and surface treatment and reclamation.

Aluminium kombinat is a unique co-operative process in Korea designed to recover alumina and electricity from low-grade anthracites high in aluminium silicate ash and low in sulphur. The kombinat consists of four energy-intensive industries: an alumina plant based on the lime-soda sintering process, a power station running on the excess heat from the sintering, a cement plant utilising the calcium silicate residue, and a conventional aluminium smelter. When combined, the plants eliminate solid waste problems and conserve much fuel., Aluminium kombinat is a unique co-operative process in Korea designed to recover alumina and electricity from low-grade anthracites high in aluminium silicate ash and low in sulphur. The kombinat consists of four energy-intensive industries: an alumina plant based on the lime-soda sintering process, a power station running on the excess heat from the sintering, a cement plant utilising the calcium silicate residue, and a conventional aluminium smelter. When combined, the plants eliminate solid waste problems and conserve much fuel.

Fires in mined-out coal seams, surface subsidence above abandoned mine workings, health hazards associated with old mine dumps, and other pollution problems are now receiving national attention in the USA. A research programme has been specifically designed to develop technology to combat the environmental impacts of mining. This consists of four sub-programmes dealing with mine waste control, mined land reclamation, process waste control and special environmental problems., Fires in mined-out coal seams, surface subsidence above abandoned mine workings, health hazards associated with old mine dumps, and other pollution problems are now receiving national attention in the USA. A research programme has been specifically designed to develop technology to combat the environmental impacts of mining. This consists of four sub-programmes dealing with mine waste control, mined land reclamation, process waste control and special environmental problems.

Oxidation smelting and roast reaction smelting are combined in direct lead smelting process. In the oxidation process the sulphur content of the bullion coming from the roasting process is reduced, and in the roast reaction process the evaporation of PBS from lead matte layer produced in the oxidation process is removed. To enhance the chemical reaction of the matte with the slag and to promote the coalescence of the matte droplets in the slag a mixer disperses the slag into the matte. The oxygen supersonic top-blowing technique used produces relatively little dust., Oxidation smelting and roast reaction smelting are combined in direct lead smelting process. In the oxidation process the sulphur content of the bullion coming from the roasting process is reduced, and in the roast reaction process the evaporation of PBS from lead matte layer produced in the oxidation process is removed. To enhance the chemical reaction of the matte with the slag and to promote the coalescence of the matte droplets in the slag a mixer disperses the slag into the matte. The oxygen supersonic top-blowing technique used produces relatively little dust.