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Trials were carried out at the Zambian copper plant in 2004 on the two reverberatory furnaces used for slag cleaning. Results provided confidence to move to one reverberatory furnace for slag cleaning by the end of 2004. The El Teniente converter (CT) was then the primary smelting vessel at Nkana, having been developed to handle 1 000 tonnes/day of bone- dry concentrate injected through tuyeres., Trials were carried out at the Zambian copper plant in 2004 on the two reverberatory furnaces used for slag cleaning. Results provided confidence to move to one reverberatory furnace for slag cleaning by the end of 2004. The El Teniente converter (CT) was then the primary smelting vessel at Nkana, having been developed to handle 1 000 tonnes/day of bone- dry concentrate injected through tuyeres.

Paper include: Recent trends in refractory technologies for BOFs in Japan, by Asano K., p.6-12, 12 refs.; The cement rotary kiln and its refractory lining, by Bartha P., 14-17, 3 refs.; Ecologic refractory management in Europe, by Eschner A., p.30-38, 1 ref.; The refractory industry in Vietnam, by Do Minh Dao, p.40-44; and New materials produced from mineral slags, by Hessenkemper H., Hohne D., Nadolny A., Lobig R. and Bienarz P., p.46-51, 5 refs., giving details of a new process for melting, forming and refining high-quality vitreous products. Other topics are filter and feeder approaches for casting, high-purity calcium aluminate cement, synthetic alumina for steel ladle linings, isostatically pressed product for steel continuous casting, high-temperature wettability in oxide- and carbon-based refractories, and insulation of ladle-tundish systems., Paper include: Recent trends in refractory technologies for BOFs in Japan, by Asano K., p.6-12, 12 refs.; The cement rotary kiln and its refractory lining, by Bartha P., 14-17, 3 refs.; Ecologic refractory management in Europe, by Eschner A., p.30-38, 1 ref.; The refractory industry in Vietnam, by Do Minh Dao, p.40-44; and New materials produced from mineral slags, by Hessenkemper H., Hohne D., Nadolny A., Lobig R. and Bienarz P., p.46-51, 5 refs., giving details of a new process for melting, forming and refining high-quality vitreous products. Other topics are filter and feeder approaches for casting, high-purity calcium aluminate cement, synthetic alumina for steel ladle linings, isostatically pressed product for steel continuous casting, high-temperature wettability in oxide- and carbon-based refractories, and insulation of ladle-tundish systems.

The 11 papers on development, 11 on modelling and 15 on fundamental research show that transport phenomena and mathematical and physical modelling are among the main areas of current investigation, most of the work being aimed at process improvement/control and equipment design. Refractory wear and furnace cooling techniques are also very active areas, where the goal is to improve design and extend the campaign life of pyrometallurgical reactors. Increased tonnages of complex polymetallic concentrates have revived interest in improving or developing new impurity removal processes. Some of the theoretical study topics discussed are intelligent process modelling, analysing heat and fluid flow, converter leaks and off-gases, oxygen efficiency, revert smelting, Cu infiltration of a refractory floor, tuyere-zone wear mechanism, impurity distribution between mattes and slags, particle temperatures in flash smelting, slag composition, equilibrium between Ni-blister and Fe-SiO slags, slag cleaning, slag reduction with natural gas, slag quality, effect of combustion gases on Cu oxidation, magnetohydrodynamic slag stirring, role of capillarity in refractory corrosion, slag-refractory reaction, gravity waves, accretion growth and compressible fluids in tuyeres. There are author and keyword indexes., The 11 papers on development, 11 on modelling and 15 on fundamental research show that transport phenomena and mathematical and physical modelling are among the main areas of current investigation, most of the work being aimed at process improvement/control and equipment design. Refractory wear and furnace cooling techniques are also very active areas, where the goal is to improve design and extend the campaign life of pyrometallurgical reactors. Increased tonnages of complex polymetallic concentrates have revived interest in improving or developing new impurity removal processes. Some of the theoretical study topics discussed are intelligent process modelling, analysing heat and fluid flow, converter leaks and off-gases, oxygen efficiency, revert smelting, Cu infiltration of a refractory floor, tuyere-zone wear mechanism, impurity distribution between mattes and slags, particle temperatures in flash smelting, slag composition, equilibrium between Ni-blister and Fe-SiO slags, slag cleaning, slag reduction with natural gas, slag quality, effect of combustion gases on Cu oxidation, magnetohydrodynamic slag stirring, role of capillarity in refractory corrosion, slag-refractory reaction, gravity waves, accretion growth and compressible fluids in tuyeres. There are author and keyword indexes.

A new raceway adiabatic flame temperature (RAFT) model has been developed where the effect of injected BOF slag has been considered. A parameter study was performed to evaluate the influence of (i) coke temperature factor, (ii) degree of silica reduction, (iii) coal powder burning degree, (iv) reduction degree of some components in injected BOF slag when leaving raceway, (v) enthalpy of coke burning and (vi) Cp value of coke. The coke burning enthalpy was found to have the largest influence on the absolute value of RAFT. In Swedish blast furnaces, the RAFT is usually kept relatively constant by adjusting the oxygen content in the blast. Therefore, the exchange ratios between the oxygen content in blast and the injected material to retain RAFT were predicted. The burning degree of coal powder was found to have the largest influence when coal powder was evaluated. Silica and silicon carbide reduction was found to have the largest influence when a change of BOF slag rate was evaluated., QC 20100525

NR 20140805

Increased knowledge in the field of gas injection, as well as the invention of the concentric tuyere for steelmaking, led to the development of the Air Liquide shrouded injector. Nitrogen injected through the annulus cools the injector tip so that the bath solidifies locally, protecting the refractory from excessive wear. The pressures at which the gases are injected prevent blockages. High levels of oxygen enrichment are therefore possible, increasing productivity without the need for tuyere punching. The benefits of the shrouded injector for the processing of Cu and Ni mattes have been demonstrated: industrial trials were run at Union Miniere's Hoboken smelter in Belgium and four shrouded injectors have replaced ten conventional tuyeres in a Peirce-Smith converter at Falconbridge's Sudbury Division smelter in Ontario., Increased knowledge in the field of gas injection, as well as the invention of the concentric tuyere for steelmaking, led to the development of the Air Liquide shrouded injector. Nitrogen injected through the annulus cools the injector tip so that the bath solidifies locally, protecting the refractory from excessive wear. The pressures at which the gases are injected prevent blockages. High levels of oxygen enrichment are therefore possible, increasing productivity without the need for tuyere punching. The benefits of the shrouded injector for the processing of Cu and Ni mattes have been demonstrated: industrial trials were run at Union Miniere's Hoboken smelter in Belgium and four shrouded injectors have replaced ten conventional tuyeres in a Peirce-Smith converter at Falconbridge's Sudbury Division smelter in Ontario.

The first prototype plant commenced operation in 1950 at Avonmouth, England, and there are now thirteen furnaces in operation, producing about 12% of zinc and 7% of lead world production in 1999; a table gives shaft area and output. The process's fundamental advantage was the ability to recover lead and zinc simultaneously from bulk concentrates; since then this advantage has been extended by its ability to treat secondary materials, including Waelz oxides, electrolytic zinc plant residues and flue dusts, through the development of hot briquetting and tuyere injection. The process also reached new levels of productivity for zinc smelting: operating furnaces can produce up to 400 t/day of zinc. Improved processes which have led to increases in the intensity of operation are discussed. The process avoids pollution of the working atmosphere, external atmosphere and receiving waters., The first prototype plant commenced operation in 1950 at Avonmouth, England, and there are now thirteen furnaces in operation, producing about 12% of zinc and 7% of lead world production in 1999; a table gives shaft area and output. The process's fundamental advantage was the ability to recover lead and zinc simultaneously from bulk concentrates; since then this advantage has been extended by its ability to treat secondary materials, including Waelz oxides, electrolytic zinc plant residues and flue dusts, through the development of hot briquetting and tuyere injection. The process also reached new levels of productivity for zinc smelting: operating furnaces can produce up to 400 t/day of zinc. Improved processes which have led to increases in the intensity of operation are discussed. The process avoids pollution of the working atmosphere, external atmosphere and receiving waters.

Over the last four years, considerable improvements in tuyere lining life have been achieved at the Arizona copper smelter by maintaining a uniform temperature in the operating converter and ensuring that there is sufficient and specific allowance for expansion in the construction of the refractory brickwork. A combination of optimised crane availability, rapid matte transfer, improved converter operating practices, new refractory applications and new installation techniques has minimised down-time. In addition, the use of large-diameter tuyere pipes and hard piping have increased blowing rates and reduced cycle times, resulting in more than 62 500 tonnes of blister copper being produced before new tuyere linings were required. The new brick installation technique is described and illustrated., Over the last four years, considerable improvements in tuyere lining life have been achieved at the Arizona copper smelter by maintaining a uniform temperature in the operating converter and ensuring that there is sufficient and specific allowance for expansion in the construction of the refractory brickwork. A combination of optimised crane availability, rapid matte transfer, improved converter operating practices, new refractory applications and new installation techniques has minimised down-time. In addition, the use of large-diameter tuyere pipes and hard piping have increased blowing rates and reduced cycle times, resulting in more than 62 500 tonnes of blister copper being produced before new tuyere linings were required. The new brick installation technique is described and illustrated.

Commissioning of the plant, in Gansu, took place in 1994. The capacity of the plant is 40 000 t/a of concentrate containing 68.5% Cu, 4% Ni, 21.5% S and 4% Fe. Quartzite is used as a flux, and oxygen and black oil are fed into the aggregate through a tuyere. Liquid products are crude blister copper and recyclable slags. Copper is processed in a Caldo-type rotating converter, off-gases are cooled and passed through an electrofilter. After the first phase of start-up it became obvious that the plant could not run at capacity (140 t/d) due to a shortage of concentrates. Capacity was decreased by changing the design of the tuyere, reducing the oxygen blow rate and increasing the consumption of black oil to preserve the heat balance. The autogenous smelting process was thus stabilised and results close to those planned were achieved., Commissioning of the plant, in Gansu, took place in 1994. The capacity of the plant is 40 000 t/a of concentrate containing 68.5% Cu, 4% Ni, 21.5% S and 4% Fe. Quartzite is used as a flux, and oxygen and black oil are fed into the aggregate through a tuyere. Liquid products are crude blister copper and recyclable slags. Copper is processed in a Caldo-type rotating converter, off-gases are cooled and passed through an electrofilter. After the first phase of start-up it became obvious that the plant could not run at capacity (140 t/d) due to a shortage of concentrates. Capacity was decreased by changing the design of the tuyere, reducing the oxygen blow rate and increasing the consumption of black oil to preserve the heat balance. The autogenous smelting process was thus stabilised and results close to those planned were achieved.

MEFOS, the Foundation for Metallogenic Research in Sweden, have been involved in work related to injection technology, specifically in the areas of dust handling (micro-powder), oxy-coal injection into blast furnaces, high temperature powder treatment, destruction of chemicals by the injection of liquids into melts, efficient cooling of liquids, controlled introduction of gases into high pressure tuyeres and variable supersonic flows in BOF., MEFOS, the Foundation for Metallogenic Research in Sweden, have been involved in work related to injection technology, specifically in the areas of dust handling (micro-powder), oxy-coal injection into blast furnaces, high temperature powder treatment, destruction of chemicals by the injection of liquids into melts, efficient cooling of liquids, controlled introduction of gases into high pressure tuyeres and variable supersonic flows in BOF.

The nature of accretions formed during gas injection can have a considerable effect on the life of the lance or the refractories in the tuyere region. There are three basic shapes of accretion formed on tuyeres: pipes, hemispheres and hollow-cored hemispheres. To obtain a better understanding of the effects of process design and operating variables on accretion formation, studies have been carried out of data gathered from operating furnaces and from previous and current mathematical and physical modelling. A rough correlation has been developed which links the material properties of the bath and the injection conditions to the type of accretion formed. The approximate size of the accretion can be related to the relative magnitudes of the primary heat flows away from the tuyere region., The nature of accretions formed during gas injection can have a considerable effect on the life of the lance or the refractories in the tuyere region. There are three basic shapes of accretion formed on tuyeres: pipes, hemispheres and hollow-cored hemispheres. To obtain a better understanding of the effects of process design and operating variables on accretion formation, studies have been carried out of data gathered from operating furnaces and from previous and current mathematical and physical modelling. A rough correlation has been developed which links the material properties of the bath and the injection conditions to the type of accretion formed. The approximate size of the accretion can be related to the relative magnitudes of the primary heat flows away from the tuyere region.

Studies were carried out of the prototype tuyere geometry for injection of inert gas through the bottom of a basic oxygen steel furnace to specify the optimal flow for bottom wear and metal penetration. Flow velocity profile development within the tuyere is thought to be significant and the experimental scheme was designed to test this. It is proposed that the design criterion for the conditions of optimal flow of the prototype geometry be based on the nondimensional mass velocity., Studies were carried out of the prototype tuyere geometry for injection of inert gas through the bottom of a basic oxygen steel furnace to specify the optimal flow for bottom wear and metal penetration. Flow velocity profile development within the tuyere is thought to be significant and the experimental scheme was designed to test this. It is proposed that the design criterion for the conditions of optimal flow of the prototype geometry be based on the nondimensional mass velocity.

Conditions in the reactor were modelled using the Computational Fluid Dynamics software FIRE. The results of one-phase flow calculation showed the advantages of top concentrate feeding, large height/width ratio of the tuyeres and an increased number of tangential inlets. Two-phase flow calculations simulated by non-reacting concentrate particles with different particle mean diameters proved the great advantages of top blowing; the result is a much better particle distribution and an enhanced retention time inside the reactor before the particles reach the cyclone wall. The next step in modelling will be to include the chemical reaction and heat balance in order to simulate both flow and converting reactions., Conditions in the reactor were modelled using the Computational Fluid Dynamics software FIRE. The results of one-phase flow calculation showed the advantages of top concentrate feeding, large height/width ratio of the tuyeres and an increased number of tangential inlets. Two-phase flow calculations simulated by non-reacting concentrate particles with different particle mean diameters proved the great advantages of top blowing; the result is a much better particle distribution and an enhanced retention time inside the reactor before the particles reach the cyclone wall. The next step in modelling will be to include the chemical reaction and heat balance in order to simulate both flow and converting reactions.

In slag processing technology, horizontal tuyeres inject fuels and reagents which function as both energy source and chemical reactant. At first sight, tuyere injection into viscous melts appears unpromising for gas-liquid contacting, yet process efficiencies are found to be high. The behaviour of the injected gas phase at projecting tuyeres in slag melts was determined by visual investigation of the processes in an isothermal transparent model and by comparative analysis of tuyere pressure signatures at full process scale in a slag fuming operation. The model was based on similarity in the modified Froude number. Relatively stable gas globes, which function essentially as refreshed, short-lived combustion chambers in the melt, had measured volumes about 12% smaller than those predicted by inviscid theory. The agitation resulting from gas globe motion indicated vigorous contacting conditions, which help to explain the observed process effectiveness. Maximum jet cavity penetration, a key factor in contacting, was predictable from turbulent jet theory on the basis of a mean cycle time for globe growth. Supersonic injection was found to increase the penetration of the jet cavity correspondingly., In slag processing technology, horizontal tuyeres inject fuels and reagents which function as both energy source and chemical reactant. At first sight, tuyere injection into viscous melts appears unpromising for gas-liquid contacting, yet process efficiencies are found to be high. The behaviour of the injected gas phase at projecting tuyeres in slag melts was determined by visual investigation of the processes in an isothermal transparent model and by comparative analysis of tuyere pressure signatures at full process scale in a slag fuming operation. The model was based on similarity in the modified Froude number. Relatively stable gas globes, which function essentially as refreshed, short-lived combustion chambers in the melt, had measured volumes about 12% smaller than those predicted by inviscid theory. The agitation resulting from gas globe motion indicated vigorous contacting conditions, which help to explain the observed process effectiveness. Maximum jet cavity penetration, a key factor in contacting, was predictable from turbulent jet theory on the basis of a mean cycle time for globe growth. Supersonic injection was found to increase the penetration of the jet cavity correspondingly.

Improvements to existing throughput require increased tuyere flow and therefore effective control of tuyere flow resistance and splashing. Splashback on to the tuyere pipe wall can make a large contribution to the coefficient of flow resistance: plant measurements have given values up to 250% of those for unused tuyeres. The average added flow resistance depends on punching frequency as well as bath conditions, and may be intrinsically smaller in reactors than in converters because of more stable bath conditions. Control of tuyere immersion depth in high-resistance tuyeres protects against reaching limiting pressures in bustle pipes. Splashing intensity appears to relate to gas dispersion behaviour in combination with tuyere immersion depth, flow rate and spacing. A test of preliminary model findings at plant scale showed reduced splashing when tuyere spacing was increased. Given the modest tuyere air supply pressure adopted in copper converting, greater understanding of the interlinked factors is needed if advances are to be made in process intensity., Improvements to existing throughput require increased tuyere flow and therefore effective control of tuyere flow resistance and splashing. Splashback on to the tuyere pipe wall can make a large contribution to the coefficient of flow resistance: plant measurements have given values up to 250% of those for unused tuyeres. The average added flow resistance depends on punching frequency as well as bath conditions, and may be intrinsically smaller in reactors than in converters because of more stable bath conditions. Control of tuyere immersion depth in high-resistance tuyeres protects against reaching limiting pressures in bustle pipes. Splashing intensity appears to relate to gas dispersion behaviour in combination with tuyere immersion depth, flow rate and spacing. A test of preliminary model findings at plant scale showed reduced splashing when tuyere spacing was increased. Given the modest tuyere air supply pressure adopted in copper converting, greater understanding of the interlinked factors is needed if advances are to be made in process intensity.

Anode copper at Chuquicamata smelter contains, at certain times, levels of arsenic which are unacceptably high for the subsequent step of electrorefining. Several tests were carried out to implement the flux injection technique as a standard practice in the anode furnace. It was found that the addition of a flux formed of 50% Na2CO3 and 50% soda ash, at around 6.5 kg flux/ton copper, leads to 91-96% arsenic extraction and 61-62% antimony extraction in 20-40 minutes of processing time. The effective slag-metal distribution coefficient for arsenic and antimony depends on Na2O and CaO contents in the slag. The rate of removal is dependent on the rate of flux injection into the copper; the flux injection rate is now calculated using an appropriate model., Anode copper at Chuquicamata smelter contains, at certain times, levels of arsenic which are unacceptably high for the subsequent step of electrorefining. Several tests were carried out to implement the flux injection technique as a standard practice in the anode furnace. It was found that the addition of a flux formed of 50% Na2CO3 and 50% soda ash, at around 6.5 kg flux/ton copper, leads to 91-96% arsenic extraction and 61-62% antimony extraction in 20-40 minutes of processing time. The effective slag-metal distribution coefficient for arsenic and antimony depends on Na2O and CaO contents in the slag. The rate of removal is dependent on the rate of flux injection into the copper; the flux injection rate is now calculated using an appropriate model.

Changes in the technology of basic refractories for the copper and nickel industries since the 1950s are surveyed for North America. Changes in pyrometallurgical processes have resulted in a trend towards higher quality refractory raw materials and improved processing technology. For example, the introduction of flash smelting, reaction-type smelting and auxiliary slag cleaning furnaces have demanded better refractory materials. Extensive field applications and improved laboratory testing procedures have helped make this transition possible., Changes in the technology of basic refractories for the copper and nickel industries since the 1950s are surveyed for North America. Changes in pyrometallurgical processes have resulted in a trend towards higher quality refractory raw materials and improved processing technology. For example, the introduction of flash smelting, reaction-type smelting and auxiliary slag cleaning furnaces have demanded better refractory materials. Extensive field applications and improved laboratory testing procedures have helped make this transition possible.

The works, which uses the Imperial Smelting Process, was commissioned in 1966 and by 1990 had increased its capacity from 3 500 to 6 600 t/month zinc and from 1 500 to 2 200 t/month lead without enlarging the furnace size. During a ten-week planned shut-down at the end of 1990 many modifications were carried out, increasing capacity to 7 500 t/month zinc and 2 500 t/month lead. In the sintering plant, the amount of SO2-rich gas supplied to the acid plant was raised from 43 500 to 50 000 Nm3/h and the venturi scrubber was replaced by an electrostatic precipitator. Oxygen enrichment was operated continuously from August 1991, because the furnace capacity was more than the rate of sinter production. Utilisation of the sintering plant rose as high as 97% and the sulphur burning rate increased. The furnace, apart from the hearth, was replaced and the shaft area enlarged from 15.3 to 19.4 m2, with a target blast designed to be more than 36 000 Nm3/h. Tuyere layout was changed to prevent slag breakouts and automatic launder jacket cleaners installed to increase lead cooling efficiency. Many other improvements and developments were also made, and shaft condition since the modifications has been very good. Coke powder injection from the tuyeres has been successfully operated since 1987., The works, which uses the Imperial Smelting Process, was commissioned in 1966 and by 1990 had increased its capacity from 3 500 to 6 600 t/month zinc and from 1 500 to 2 200 t/month lead without enlarging the furnace size. During a ten-week planned shut-down at the end of 1990 many modifications were carried out, increasing capacity to 7 500 t/month zinc and 2 500 t/month lead. In the sintering plant, the amount of SO2-rich gas supplied to the acid plant was raised from 43 500 to 50 000 Nm3/h and the venturi scrubber was replaced by an electrostatic precipitator. Oxygen enrichment was operated continuously from August 1991, because the furnace capacity was more than the rate of sinter production. Utilisation of the sintering plant rose as high as 97% and the sulphur burning rate increased. The furnace, apart from the hearth, was replaced and the shaft area enlarged from 15.3 to 19.4 m2, with a target blast designed to be more than 36 000 Nm3/h. Tuyere layout was changed to prevent slag breakouts and automatic launder jacket cleaners installed to increase lead cooling efficiency. Many other improvements and developments were also made, and shaft condition since the modifications has been very good. Coke powder injection from the tuyeres has been successfully operated since 1987.

The furnace at Cockle Creek, New South Wales, was constructed in 1961 and is the oldest facility using the Imperial Smelting Process in operation. In recent years there have been significant improvements in many areas of operation, including production, safety, hygiene and environmental performance. Sintering plant capacity has been raised by a combination of increasing gas volume from 77 000 Nm3/h in 1989 to 82 000 Nm3/h in 1992, emphasising plant utilisation and replacing sinter returns particles with pelletised oxide material. The acid plant, built to produce 250 tonnes/d sulphuric acid, now averages 517 t/d: drying and absorption towers have been replaced, the wet gas cleaning section is being uprated and a water cooling tower has been installed. Furnace production has been improved by identification of key operating parameters critical for the continuous tapping of slag and lead bullion: the tuyeres were repositioned and their angle of inclination changed to ensure vigorous interaction of the raceways with the slag/lead pool, allow mixing of speiss with slag, and render the operation less sensitive to furnace movement. Modification of the lead splash condenser increased efficiency by 14%, by reducing blue powder generation from 1.85 to 1.60 tonne/equivalent target blast hour. Replacing the furnace, disintegrator, booster fan and blower, upgrading gas washing and charge preparation systems, raising the condenser roof and enlarging the pump sump and flux bath will increase furnace output to 92 000 t/y zinc., The furnace at Cockle Creek, New South Wales, was constructed in 1961 and is the oldest facility using the Imperial Smelting Process in operation. In recent years there have been significant improvements in many areas of operation, including production, safety, hygiene and environmental performance. Sintering plant capacity has been raised by a combination of increasing gas volume from 77 000 Nm3/h in 1989 to 82 000 Nm3/h in 1992, emphasising plant utilisation and replacing sinter returns particles with pelletised oxide material. The acid plant, built to produce 250 tonnes/d sulphuric acid, now averages 517 t/d: drying and absorption towers have been replaced, the wet gas cleaning section is being uprated and a water cooling tower has been installed. Furnace production has been improved by identification of key operating parameters critical for the continuous tapping of slag and lead bullion: the tuyeres were repositioned and their angle of inclination changed to ensure vigorous interaction of the raceways with the slag/lead pool, allow mixing of speiss with slag, and render the operation less sensitive to furnace movement. Modification of the lead splash condenser increased efficiency by 14%, by reducing blue powder generation from 1.85 to 1.60 tonne/equivalent target blast hour. Replacing the furnace, disintegrator, booster fan and blower, upgrading gas washing and charge preparation systems, raising the condenser roof and enlarging the pump sump and flux bath will increase furnace output to 92 000 t/y zinc.

The Avonmouth Imperial Smelting blast furnace and sintering plant were uprated in 1988, but zinc production in the following 12 months was only 85 000 tonnes and only by 1992 was a rolling 12-month production of 110 000 t consistently achieved. There were initial shortages of sinter due to an offset in uprate timing. Greater difficulties were experienced in operating the larger furnace, particularly on start-up: there were serious slagging problems and a greater tendency for iron production. Deleterious trends in slag chemistry were coincidental. There were refractory problems in the shaft furnace and condenser. Problems in commissioning the wet gas and sinter tip end fans, and difficulties in obtaining sufficient sinter hardness, resulted in shortages of sinter. The full benefits of the sinter-acid plant uprate were not realised due to a late change in design to dispense with sinter gas recirculation, though this was offset by successful use of oxygen. The problems have largely been overcome by a determined attack on their true causes. Data analysis is now more thorough, action taken more cautious, monitoring used more extensively and external advice sought more readily. Furnace zinc output capacity is planned to rise to 120 000 t/y within two years., The Avonmouth Imperial Smelting blast furnace and sintering plant were uprated in 1988, but zinc production in the following 12 months was only 85 000 tonnes and only by 1992 was a rolling 12-month production of 110 000 t consistently achieved. There were initial shortages of sinter due to an offset in uprate timing. Greater difficulties were experienced in operating the larger furnace, particularly on start-up: there were serious slagging problems and a greater tendency for iron production. Deleterious trends in slag chemistry were coincidental. There were refractory problems in the shaft furnace and condenser. Problems in commissioning the wet gas and sinter tip end fans, and difficulties in obtaining sufficient sinter hardness, resulted in shortages of sinter. The full benefits of the sinter-acid plant uprate were not realised due to a late change in design to dispense with sinter gas recirculation, though this was offset by successful use of oxygen. The problems have largely been overcome by a determined attack on their true causes. Data analysis is now more thorough, action taken more cautious, monitoring used more extensively and external advice sought more readily. Furnace zinc output capacity is planned to rise to 120 000 t/y within two years.

The use of pilot plant facilities in pyrometallurgy is discussed. Aspects on the feasibility of laboratory, pilot and/or plant investigations are presented. Studies undertaken at MEFOS (The Foundation for Metallurgical Research) in Sweden, in relation to bath smelting are reported. A major issue has been the introduction of gases and powders through the bottom, sidewall and the top of the vessels. Injection technology trials in pilot plant at MEFOS are described., The use of pilot plant facilities in pyrometallurgy is discussed. Aspects on the feasibility of laboratory, pilot and/or plant investigations are presented. Studies undertaken at MEFOS (The Foundation for Metallurgical Research) in Sweden, in relation to bath smelting are reported. A major issue has been the introduction of gases and powders through the bottom, sidewall and the top of the vessels. Injection technology trials in pilot plant at MEFOS are described.

The invention of the concentric tuyere, which shrouded the discharging oxygen stream with hydrocarbon, transformed the steelmaking landscape spawning new processes. The birth of the new invention and its evolution to create new metallurgical processes are reviewed. The concepts of the concentric tuyere and gas shrouding are now being applied to process developments for non-ferrous metal production such as lead and copper., The invention of the concentric tuyere, which shrouded the discharging oxygen stream with hydrocarbon, transformed the steelmaking landscape spawning new processes. The birth of the new invention and its evolution to create new metallurgical processes are reviewed. The concepts of the concentric tuyere and gas shrouding are now being applied to process developments for non-ferrous metal production such as lead and copper.

The discovery in 1961 that fine lump ore could be continuously smelted in a slowly flowing stream of blast furnace hot metal which was sequentially lanced with oxygen, led to research into bath smelting and the development of the WORCRA process. Zoned horizontal furnaces with both tuyeres and lances were evaluated. The problems and advantages of each are discussed together with the interplay of kinetics and thermodynamics in systems involving quiescent and turbulent zones and countercurrent movement of slag. Metal was produced in the same furnace as smelting and slag cleaning were achieved continously. Currently WORCRA principles are being used in the smelting of composites of steelwork dusts and a variety of carbonaceous wastes to produce foundry-type iron., The discovery in 1961 that fine lump ore could be continuously smelted in a slowly flowing stream of blast furnace hot metal which was sequentially lanced with oxygen, led to research into bath smelting and the development of the WORCRA process. Zoned horizontal furnaces with both tuyeres and lances were evaluated. The problems and advantages of each are discussed together with the interplay of kinetics and thermodynamics in systems involving quiescent and turbulent zones and countercurrent movement of slag. Metal was produced in the same furnace as smelting and slag cleaning were achieved continously. Currently WORCRA principles are being used in the smelting of composites of steelwork dusts and a variety of carbonaceous wastes to produce foundry-type iron.

A QSL demonstration plant was operated within the Berzelius lead-zinc smelter in Duisburg, Germany from 1981-1986. A total of 100 000 tonnes of both high and low grade lead bearing feed materials were treated. Four commercial plants have been designed and built and one in Stolberg commenced operation in August 1990. Experience from this plant has shown that it is possible to produce lead bullion and low lead slags from a wide range of feed materials (concentrates and secondaries) as well as sulphuric acid from the SO2 rich offgas. Certain modifications to the original design were necessary: a lead layer along the entire length of the reduction zone aids the slag reduction process significantly. Efforts continue to extend the injector lifetimes in order to reduce operating costs., A QSL demonstration plant was operated within the Berzelius lead-zinc smelter in Duisburg, Germany from 1981-1986. A total of 100 000 tonnes of both high and low grade lead bearing feed materials were treated. Four commercial plants have been designed and built and one in Stolberg commenced operation in August 1990. Experience from this plant has shown that it is possible to produce lead bullion and low lead slags from a wide range of feed materials (concentrates and secondaries) as well as sulphuric acid from the SO2 rich offgas. Certain modifications to the original design were necessary: a lead layer along the entire length of the reduction zone aids the slag reduction process significantly. Efforts continue to extend the injector lifetimes in order to reduce operating costs.

Matte converting operations have traditionally been carried out in horizontal reactors. In the last two decades intensively stirred vertical reactors have been developed with submerged gas injection through lances, sometimes with powder injection, to obtain more efficient gas-liquid and solid-liquid contacting. Previous matte converting studies are briefly reviewed and recent developments at the G.K.Williams Cooperative Research Centre for Extractive Metallurgy at the University of Melbourne are discussed. These include: novel injection of flux through the tuyeres of a P-S converter; mathematical and physical modelling of a Sirosmelt lance; slopping in horizontal reactors; plant investigations on the copper anode furnace; and the helical plug lance, a novel gas injection device., Matte converting operations have traditionally been carried out in horizontal reactors. In the last two decades intensively stirred vertical reactors have been developed with submerged gas injection through lances, sometimes with powder injection, to obtain more efficient gas-liquid and solid-liquid contacting. Previous matte converting studies are briefly reviewed and recent developments at the G.K.Williams Cooperative Research Centre for Extractive Metallurgy at the University of Melbourne are discussed. These include: novel injection of flux through the tuyeres of a P-S converter; mathematical and physical modelling of a Sirosmelt lance; slopping in horizontal reactors; plant investigations on the copper anode furnace; and the helical plug lance, a novel gas injection device.

Virtually all routes for the extraction of non-ferrous metals use submerged injection in some way. Matte converting is the most widespread non-ferrous bath smelting process and gas is introduced in nickel and copper converting and the QSL process through submerged tuyeres. In a number of processes, such as the Mitsubishi and Sirosmelt-Isasmelt processes, a lance is used which has certain advantages over the tuyere. Solid reagent or feed materials are sometimes injected, as in zinc fuming. Several problems prevent the effective use of the technique such as tuyere blockage and tuyere and refractory erosion., Virtually all routes for the extraction of non-ferrous metals use submerged injection in some way. Matte converting is the most widespread non-ferrous bath smelting process and gas is introduced in nickel and copper converting and the QSL process through submerged tuyeres. In a number of processes, such as the Mitsubishi and Sirosmelt-Isasmelt processes, a lance is used which has certain advantages over the tuyere. Solid reagent or feed materials are sometimes injected, as in zinc fuming. Several problems prevent the effective use of the technique such as tuyere blockage and tuyere and refractory erosion.

In order to optimise the heat balance of the Teniente Converter process at the Caletones smelter, Chile, bone-dry concentrate was fed through specially designed tuyeres submerged in the reactor molten bath. Smelting capacity has increased to 2 000 tons/day of concentrate. There has been an important increase in the concentrate:matte ratio, making the addition of matte unneccessary in order to balance the heat process requirement., In order to optimise the heat balance of the Teniente Converter process at the Caletones smelter, Chile, bone-dry concentrate was fed through specially designed tuyeres submerged in the reactor molten bath. Smelting capacity has increased to 2 000 tons/day of concentrate. There has been an important increase in the concentrate:matte ratio, making the addition of matte unneccessary in order to balance the heat process requirement.

The Noranda continuous smelting process at the Horne smelter was commissioned in 1973 and since then the reactor capacity has increased fourfold and it is now the principal smelting unit. This evolution has been achieved by a steady stream of technical developments that has allowed the vessel to smelt several types of metal-bearing materials while maintaining an adequate control of metallurgical parameters. The main reactor improvements and their efects on the capacity and control of the Noranda process are decribed., The Noranda continuous smelting process at the Horne smelter was commissioned in 1973 and since then the reactor capacity has increased fourfold and it is now the principal smelting unit. This evolution has been achieved by a steady stream of technical developments that has allowed the vessel to smelt several types of metal-bearing materials while maintaining an adequate control of metallurgical parameters. The main reactor improvements and their efects on the capacity and control of the Noranda process are decribed.

An injector has been developed to allow accurate dosing and pneumatic conveying of materials into industrial processes on a continuous or batch basis, at relatively small flow rates and over moderate distances. The Simon-Macawber injector comprises a lock hopper and injector vessel with metering feeder, associated valve controls and manifolds, forming a self-contained pressure vessel which can overcome process back-pressures and handle a wide range of injectants. The system is used by British Steel for injecting granular coal into blast furnace tuyeres, at distances of up to 210 m, and by Davy McKee for controlled injection of electric arc furnace dust into a plasma arc treatment facility. An innovative method has also been developed for injecting various materials into a foundry cupola or, from the same injection system, treating molten iron in a holding ladle., An injector has been developed to allow accurate dosing and pneumatic conveying of materials into industrial processes on a continuous or batch basis, at relatively small flow rates and over moderate distances. The Simon-Macawber injector comprises a lock hopper and injector vessel with metering feeder, associated valve controls and manifolds, forming a self-contained pressure vessel which can overcome process back-pressures and handle a wide range of injectants. The system is used by British Steel for injecting granular coal into blast furnace tuyeres, at distances of up to 210 m, and by Davy McKee for controlled injection of electric arc furnace dust into a plasma arc treatment facility. An innovative method has also been developed for injecting various materials into a foundry cupola or, from the same injection system, treating molten iron in a holding ladle.

Contents: Atmospheric gases in liquid metal processes, by Felski A., Waldron S.N. and Moore C., p.A1-25, 20 refs.; Model studies of gas injection at high flow rates using water and mercury, by Nilmani M. and Robertson D.G.C., p.B1-36, 16 refs.; Bubbling behaviour in molten metals, by Irons G.A. and Guthrie R.I.L., p.C1-13, 12 refs.; Fas dispersion at an annular tuyere, by Chalkley M.E. and Wraith A.E., p.D1-23, 12 refs.; Penetration of particle/gas jets into liquids, by Engh T.A., Larsen K. and Venas K., p.E1-33, 19 refs.; Characterisation of jet behaviour at a submerged orifice in liquid metals, by Mori K., Ozawa Y. and Sano M., p.F1-6, 5 refs.; Heat transfer in tuyeres for oxygen bottom blowing converters, by Denier G., Grosiean J.C. and Zannetta H., p.G1-24, 3 refs.; On the modelling of submerged gas jets, by McKelliget J.W. and others, p.H1-19, 26 refs.; A physical modelling-based approach to some problems associated with submerged gas injection into liquid metals melts, by Robertson T. and Sabharwal A.K., p.11-29, 7 refs.; The behaviour of the third phase produced in gas bubble-liquid reactions, by Conochie D.S. and Robertson D.G.C., p.J1-21, 13 refs.; A ternary interfacial energy diagram, by Conochie D.S. and Robertson D.H.C., p.K1-8, 1 ref.; Mechanical tuyere punching of copper converters, by Aimone F.M. and Fern K.A., p.L1-21; The cupellation of lead-copper-silver bullion by the bottom injection of oxygen, by Hallett D.J., Hendra P.R. and Tait R.J., p.M1-10, 3 refs.; Effects of injecting argon into the mould of a continuous slab caster, by McPherson N.A., p.N1-8,3 refs.; Nitrogen alloying a low-alloy steel in the ladle by injection of calcium cyanamiade (CaCN2) powder with nitrogen (N2) as a carrier gas, by Ritakallio P., p.P1-24, 19 refs., Contents: Atmospheric gases in liquid metal processes, by Felski A., Waldron S.N. and Moore C., p.A1-25, 20 refs.; Model studies of gas injection at high flow rates using water and mercury, by Nilmani M. and Robertson D.G.C., p.B1-36, 16 refs.; Bubbling behaviour in molten metals, by Irons G.A. and Guthrie R.I.L., p.C1-13, 12 refs.; Fas dispersion at an annular tuyere, by Chalkley M.E. and Wraith A.E., p.D1-23, 12 refs.; Penetration of particle/gas jets into liquids, by Engh T.A., Larsen K. and Venas K., p.E1-33, 19 refs.; Characterisation of jet behaviour at a submerged orifice in liquid metals, by Mori K., Ozawa Y. and Sano M., p.F1-6, 5 refs.; Heat transfer in tuyeres for oxygen bottom blowing converters, by Denier G., Grosiean J.C. and Zannetta H., p.G1-24, 3 refs.; On the modelling of submerged gas jets, by McKelliget J.W. and others, p.H1-19, 26 refs.; A physical modelling-based approach to some problems associated with submerged gas injection into liquid metals melts, by Robertson T. and Sabharwal A.K., p.11-29, 7 refs.; The behaviour of the third phase produced in gas bubble-liquid reactions, by Conochie D.S. and Robertson D.G.C., p.J1-21, 13 refs.; A ternary interfacial energy diagram, by Conochie D.S. and Robertson D.H.C., p.K1-8, 1 ref.; Mechanical tuyere punching of copper converters, by Aimone F.M. and Fern K.A., p.L1-21; The cupellation of lead-copper-silver bullion by the bottom injection of oxygen, by Hallett D.J., Hendra P.R. and Tait R.J., p.M1-10, 3 refs.; Effects of injecting argon into the mould of a continuous slab caster, by McPherson N.A., p.N1-8,3 refs.; Nitrogen alloying a low-alloy steel in the ladle by injection of calcium cyanamiade (CaCN2) powder with nitrogen (N2) as a carrier gas, by Ritakallio P., p.P1-24, 19 refs.

Les Forges du Saint-Maurice was an integrated industrial concern, specialising in the production of semi-finished wrought iron and finished cast iron, that operated almost without interuption between 1734 and 1883. The history of this concern is described., Les Forges du Saint-Maurice was an integrated industrial concern, specialising in the production of semi-finished wrought iron and finished cast iron, that operated almost without interuption between 1734 and 1883. The history of this concern is described.

We report the first detailed chemical, microstructural and thermal analyses of a growing corpus of metallurgical tuyeres from the wider archaeological landscape of Great Zimbabwe in southern Africa. Of note is the fusion of the tuyeres in multiples, suggestive of widespread use of natural draft iron smelting technologies for large-scale production of iron most likely during the zenith period of Great Zimbabwe (ca 12th-16th century AD). Considerable variation in elemental composition between sites attributable to the adaptation of ceramic technology to local clay materials across the landscape is established through XRF analytical techniques. We also pick from petrographic studies, a bias towards self-tempered clays dominated by silt and fine sand at some sites and the tendency for technicians to crush coarse sand and gravel a the others. Yet, and despite such variability in ceramic technology approaches, none of the studied sample had started to deform or melt at 1400oC, the maximum temperature of the furnace used for thermal analyses in the laboratory, revealing an unusually high refractoriness. We argue that such novel technologies natural draft furnaces would have built on an equally high degree of knowledge in ceramic technology, skilled prospection and manipulation of the material world. This brings out yet another intimate human-landscape interaction vividly depicted in Great Zimbabwe’s famous drystone architecture Great Zimbabwe

Cast house is the heart of blast furnace operation. A stable blast furnace operation requires proper control of hot metal and slag drainage from the hearth. Various problems are encountered if the hearth liquid level exceeds above a critical limit that leads to an unstable blast furnace condition. Moreover, operating too often to control liquid level is also not recommended, as operational cost is increased and refractory erosion increases. Therefore, there is a need to understand the reason that prevails in the abnormal hearth liquid level situations. Understanding the effect of increased hearth liquid level on blast furnace process parameters will enable blast furnace operation to take the proactive actions of controlling the blast furnace abnormality. In the present review, an attempt is made to establish a correlational research to understand the effect on hearth liquid level on various casting parameters and blast furnace process conditions. The adverse effect of hearth liquid level build-up on the state of dead man, gas permeability, tuyere life, hearth linings, slag delay and furnace wall heat load is studied. The various casting strategies adopted in blast furnace operation are discussed along with their advantages and disadvantages, and finally, the recommendations are made to operate the liquid level on narrow band. (Authors.), Cast house is the heart of blast furnace operation. A stable blast furnace operation requires proper control of hot metal and slag drainage from the hearth. Various problems are encountered if the hearth liquid level exceeds above a critical limit that leads to an unstable blast furnace condition. Moreover, operating too often to control liquid level is also not recommended, as operational cost is increased and refractory erosion increases. Therefore, there is a need to understand the reason that prevails in the abnormal hearth liquid level situations. Understanding the effect of increased hearth liquid level on blast furnace process parameters will enable blast furnace operation to take the proactive actions of controlling the blast furnace abnormality. In the present review, an attempt is made to establish a correlational research to understand the effect on hearth liquid level on various casting parameters and blast furnace process conditions. The adverse effect of hearth liquid level build-up on the state of dead man, gas permeability, tuyere life, hearth linings, slag delay and furnace wall heat load is studied. The various casting strategies adopted in blast furnace operation are discussed along with their advantages and disadvantages, and finally, the recommendations are made to operate the liquid level on narrow band. (Authors.)

The copper smelting industry faces increasingly stringent environmental regulations and must continue driving innovation to reduce energy usage in its production chain. With the coming of age of bottom-blowing copper technologies in China over the last decade, much renewed attention has been brought to tuyere bath smelting for clean copper-making. Since bottom-blowing sonic injection was originally developed and implemented in steelmaking in the 1970s and lead smelting in the 1990s, the time seems appropriate to revisit the sonic injection concepts and dispel some myths. After reviewing the trends in the copper industry and providing a brief historical context of research and development related to sonic injection, the author presents a comparison of the main submerged tuyere bath smelting technologies, namely the Noranda reactor, the Teniente converter, and the Chinese bottom-blowing smelting furnace for copper, and the Queneau-Schuhmann-Lurgi reactor for lead. The core of the article, however, consists of a brief description of the fundamental theories for sonic injection (jetting regime) and sonic flow mapping to illustrate the relationship between the minimum tuyere back-pressure required to achieve sonic flow and the tuyere internal diameter. The article also offers a comparison between side- and bottom-blowing in jetting regime before concluding with the author's vision of the new trend in submerged-tuyere bath smelting., The copper smelting industry faces increasingly stringent environmental regulations and must continue driving innovation to reduce energy usage in its production chain. With the coming of age of bottom-blowing copper technologies in China over the last decade, much renewed attention has been brought to tuyere bath smelting for clean copper-making. Since bottom-blowing sonic injection was originally developed and implemented in steelmaking in the 1970s and lead smelting in the 1990s, the time seems appropriate to revisit the sonic injection concepts and dispel some myths. After reviewing the trends in the copper industry and providing a brief historical context of research and development related to sonic injection, the author presents a comparison of the main submerged tuyere bath smelting technologies, namely the Noranda reactor, the Teniente converter, and the Chinese bottom-blowing smelting furnace for copper, and the Queneau-Schuhmann-Lurgi reactor for lead. The core of the article, however, consists of a brief description of the fundamental theories for sonic injection (jetting regime) and sonic flow mapping to illustrate the relationship between the minimum tuyere back-pressure required to achieve sonic flow and the tuyere internal diameter. The article also offers a comparison between side- and bottom-blowing in jetting regime before concluding with the author's vision of the new trend in submerged-tuyere bath smelting.

A digital imaging system based on a colour charge-coupled device within the gas-cooling and dustproof functions was established to capture the combustion radiation in the tuyere zone. For instance, images of tuyere zones of 2 000 and 2 500 m3 blast furnaces were detected through a peephole in front of the blowpipe by the application of digital imaging and image processing techniques, and the temperature distributions were also calculated. Some measurements were used to improve the accuracy of the results, and the combustion behaviour was also analysed. (Authors.), A digital imaging system based on a colour charge-coupled device within the gas-cooling and dustproof functions was established to capture the combustion radiation in the tuyere zone. For instance, images of tuyere zones of 2 000 and 2 500 m3 blast furnaces were detected through a peephole in front of the blowpipe by the application of digital imaging and image processing techniques, and the temperature distributions were also calculated. Some measurements were used to improve the accuracy of the results, and the combustion behaviour was also analysed. (Authors.)

Coke oven gas (COG), as an environment-friendly source, is projected to be introduced into the COREX process to reduce solid fuel consumption. In this paper, a static model has been developed based on mass and heat balance, which can calculate characteristics of melter gasifier, such as the raceway adiabatic flame temperature (RAFT), volume and component of bosh gas. The results showed that compared with N2, the COG injection from tuyere is more effective on reducing the RAFT and improving the bosh gas volume. The quantity of gas injected is limited for the RAFT, and without other thermal compensation, the largest injection quantity is about 150 Nm3/t. The quantity of gas injection can be increased by preheating tuyere oxygen, adjustment of fuel structure and addition of tuyere oxygen. Coke-oven gas injection can promote the reduction and hearth permeability, decrease the raceway adiabatic flame temperature and protect the tuyere, which is beneficial to COREX operation. (Authors.), Coke oven gas (COG), as an environment-friendly source, is projected to be introduced into the COREX process to reduce solid fuel consumption. In this paper, a static model has been developed based on mass and heat balance, which can calculate characteristics of melter gasifier, such as the raceway adiabatic flame temperature (RAFT), volume and component of bosh gas. The results showed that compared with N2, the COG injection from tuyere is more effective on reducing the RAFT and improving the bosh gas volume. The quantity of gas injected is limited for the RAFT, and without other thermal compensation, the largest injection quantity is about 150 Nm3/t. The quantity of gas injection can be increased by preheating tuyere oxygen, adjustment of fuel structure and addition of tuyere oxygen. Coke-oven gas injection can promote the reduction and hearth permeability, decrease the raceway adiabatic flame temperature and protect the tuyere, which is beneficial to COREX operation. (Authors.)

A series of experiments using multi-tubed nozzles showed that the impact stress distribution acting on the furnace lining increased gradually with distance from the bottom of the furnace and reached a maximum below the slag line, due to intensive circulation and agitation of the liquid metal. When 6 nozzles were installed over the furnace bottom, the impact stress acting on the furnace lining around the upper part of the liquid pool increased with supplied gas pressure, due to the impact of bubbles, surface waves and the circulation flow of the liquid metal. At constant gas pressures, impact stress decreased with equivalent nozzle diameter. Analysis of the combined effects of impact stress and shear stress on the furnace wall indicated that the lining was subject to the most severe erosion at 85-96% of liuqid height., A series of experiments using multi-tubed nozzles showed that the impact stress distribution acting on the furnace lining increased gradually with distance from the bottom of the furnace and reached a maximum below the slag line, due to intensive circulation and agitation of the liquid metal. When 6 nozzles were installed over the furnace bottom, the impact stress acting on the furnace lining around the upper part of the liquid pool increased with supplied gas pressure, due to the impact of bubbles, surface waves and the circulation flow of the liquid metal. At constant gas pressures, impact stress decreased with equivalent nozzle diameter. Analysis of the combined effects of impact stress and shear stress on the furnace wall indicated that the lining was subject to the most severe erosion at 85-96% of liuqid height.

Operational data for thirteen bath smelting processes are analysed with respect to oxygen utilisation, smelting intensity and other features related to metallurgical efficiency and environmental control. The processes cover both old and new designs, batch and continuous reactors, tuyere and lance injection and reduction as well as oxidation chemistry. The processes studied are: Peirce-Smith copper converters, Noranda process, Teniente process, Vanyukov process, Baiyin process, conventional zinc fuming furnace, QSL process, TBRCs, Mitsubishi process, Isasmelt process, Sirosmelt process and the Inco top-blowing, bottom-stirring process. The smelting intensities of these very different reactors were compared by a measure of their specific oxygen consumption rate. Comparisons of reactor intensity of bath smelting with flash smelting and oxygen steel making are presented., Operational data for thirteen bath smelting processes are analysed with respect to oxygen utilisation, smelting intensity and other features related to metallurgical efficiency and environmental control. The processes cover both old and new designs, batch and continuous reactors, tuyere and lance injection and reduction as well as oxidation chemistry. The processes studied are: Peirce-Smith copper converters, Noranda process, Teniente process, Vanyukov process, Baiyin process, conventional zinc fuming furnace, QSL process, TBRCs, Mitsubishi process, Isasmelt process, Sirosmelt process and the Inco top-blowing, bottom-stirring process. The smelting intensities of these very different reactors were compared by a measure of their specific oxygen consumption rate. Comparisons of reactor intensity of bath smelting with flash smelting and oxygen steel making are presented.

For tuyere injection at steady flow, the dynamic tuyere pressure appears to provide a faithful and sensitive indication of the dispersion process near the tuyere mouth. Comparisons of the dynamic tuyere pressure response for air-water and air-mercury systems under similar conditions of flow and tuyere geometry suggest that the main features of the dispersion processes in the two systems correspond. Bubble volumes in mercury that are estimated from the time scale of pressure cycles show good agreement with theories of two-stage bubble growth, previously tested only in water., For tuyere injection at steady flow, the dynamic tuyere pressure appears to provide a faithful and sensitive indication of the dispersion process near the tuyere mouth. Comparisons of the dynamic tuyere pressure response for air-water and air-mercury systems under similar conditions of flow and tuyere geometry suggest that the main features of the dispersion processes in the two systems correspond. Bubble volumes in mercury that are estimated from the time scale of pressure cycles show good agreement with theories of two-stage bubble growth, previously tested only in water.

At the Horne Division of Noranda Mines Ltd., the Noranda process now smelts approximately 350 000 short tons of concentrate a year which is 40 of total smelter throuput. Campaigns are averaging 200 days and refractory consumption is much lower than in the conventional smelter., At the Horne Division of Noranda Mines Ltd., the Noranda process now smelts approximately 350 000 short tons of concentrate a year which is 40 of total smelter throuput. Campaigns are averaging 200 days and refractory consumption is much lower than in the conventional smelter.