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Technologies developed by the company are described. The Outotec flash smelting process is based on the utilisation of the internal energy of the feed material to drive the smelting process. Finely ground sulphidic Cu concentrate is mixed with oxygen-enriched air to form a rapidly reacting suspension of particles and gas in the furnace reaction shaft, and sulphide compounds in the feed ignite, oxidise and release heat to provide fuel for the process. In the Kennecott-Outotec flash converting process oxidation of the matte occurs under highly oxidising conditions so that sulphidic matte is converted to metallic Cu. Oxygen-enriched air or pure oxygen can be used for the oxidation of fine matte particles. The furnace can operate autogenously without additional fossil fuels. The Outotec direct blister flash smelting process involves the smelting of a concentrate preferably containing more than 30% Cu to directly produce blister Cu. In the Outotec nickel flash smelting process sulphide Ni concentrate is processed to form Ni matte and slag and the matte transferred to Peirce Smith converters for the production of high-grade matte. The direct nickel flash smelting process involves the production of high-grade Ni matte with low Fe content without the need for converters. Metal values in smelting and converter slags may be recovered in an electric furnace or slag concentrator. In the electric Outotec slag cleaning furnace Cu or Ni matte is separated to the bottom of the furnace and the matte sent to a converter. The Outotec Ausmelt process is particularly suitable for the processing of secondary Cu and Pb materials and is also used to produce metallic Sn directly from concentrates. The Outotec Kaldo furnace is employed for the conversion and refining of precious metals, Cu and Pb. A case study is presented of the use of flash smelting for the production of blister Cu at a smelter in Zambia, with reference to the use of thermodynamic modelling to predict the liquidus temperat, Technologies developed by the company are described. The Outotec flash smelting process is based on the utilisation of the internal energy of the feed material to drive the smelting process. Finely ground sulphidic Cu concentrate is mixed with oxygen-enriched air to form a rapidly reacting suspension of particles and gas in the furnace reaction shaft, and sulphide compounds in the feed ignite, oxidise and release heat to provide fuel for the process. In the Kennecott-Outotec flash converting process oxidation of the matte occurs under highly oxidising conditions so that sulphidic matte is converted to metallic Cu. Oxygen-enriched air or pure oxygen can be used for the oxidation of fine matte particles. The furnace can operate autogenously without additional fossil fuels. The Outotec direct blister flash smelting process involves the smelting of a concentrate preferably containing more than 30% Cu to directly produce blister Cu. In the Outotec nickel flash smelting process sulphide Ni concentrate is processed to form Ni matte and slag and the matte transferred to Peirce Smith converters for the production of high-grade matte. The direct nickel flash smelting process involves the production of high-grade Ni matte with low Fe content without the need for converters. Metal values in smelting and converter slags may be recovered in an electric furnace or slag concentrator. In the electric Outotec slag cleaning furnace Cu or Ni matte is separated to the bottom of the furnace and the matte sent to a converter. The Outotec Ausmelt process is particularly suitable for the processing of secondary Cu and Pb materials and is also used to produce metallic Sn directly from concentrates. The Outotec Kaldo furnace is employed for the conversion and refining of precious metals, Cu and Pb. A case study is presented of the use of flash smelting for the production of blister Cu at a smelter in Zambia, with reference to the use of thermodynamic modelling to predict the liquidus temperat

The availability of the off-gas line is essential for the productivity of the Cu flash smelting process. In addition to heat recovery and dust separation. the off-gas line is required to function as a chemical reactor. Sulphation reactions are inevitable in the heat recovery boiler atmosphere and they should take place in regions that enable easy dust handling and maximise heat recovery. The oxygen potential of the gas line should be monitored and used as a controlling parameter which affects the oxygen feed. An appropriate amount of oxygen should be available for dust sulphation reactions, while excess oxygen will lead to weak acid formation and corrosion phenomena. Accretion formation in the gas line can be minimised by optimising the dust oxidation and sulphation behaviour. Sulphation reactions should initiate as early as possible in the boiler, before the dust particles come into contact with the boiler tubes. The dust should be in oxide form when it enters the boiler. Injecting oxygen into gas through the flash furnace settler roof results in dust oxidation in the up-take shaft and enables dust sulphation to begin as early in the boiler as the temperature decrease allows. Injecting sulphation air into the boiler radiation section supplies the amount of oxygen and turbulence required for dust sulphation reactions. Computational fluid dynamics (CFD) modelling is an effective tool for optimising the oxygen partial pressure and flow field in the off-gas line. The optimisation of injection locations, jet penetration and velocity and oxygen amount of the injection nozzles can be performed through modelling. Details are given of the advanced CFD model developed by Outotec for predicting dust sulphation behaviour in the boiler and the possible deposition locations of the dust and which can be used to determine the most effective locations and parameters for oxygen and air injection., The availability of the off-gas line is essential for the productivity of the Cu flash smelting process. In addition to heat recovery and dust separation. the off-gas line is required to function as a chemical reactor. Sulphation reactions are inevitable in the heat recovery boiler atmosphere and they should take place in regions that enable easy dust handling and maximise heat recovery. The oxygen potential of the gas line should be monitored and used as a controlling parameter which affects the oxygen feed. An appropriate amount of oxygen should be available for dust sulphation reactions, while excess oxygen will lead to weak acid formation and corrosion phenomena. Accretion formation in the gas line can be minimised by optimising the dust oxidation and sulphation behaviour. Sulphation reactions should initiate as early as possible in the boiler, before the dust particles come into contact with the boiler tubes. The dust should be in oxide form when it enters the boiler. Injecting oxygen into gas through the flash furnace settler roof results in dust oxidation in the up-take shaft and enables dust sulphation to begin as early in the boiler as the temperature decrease allows. Injecting sulphation air into the boiler radiation section supplies the amount of oxygen and turbulence required for dust sulphation reactions. Computational fluid dynamics (CFD) modelling is an effective tool for optimising the oxygen partial pressure and flow field in the off-gas line. The optimisation of injection locations, jet penetration and velocity and oxygen amount of the injection nozzles can be performed through modelling. Details are given of the advanced CFD model developed by Outotec for predicting dust sulphation behaviour in the boiler and the possible deposition locations of the dust and which can be used to determine the most effective locations and parameters for oxygen and air injection.

In 1995 Ni production capacity at Harjavalta was increased from 17 000 t/a to 52 000 t/a by replacing Peirce-Smith converting, in use since 1959, with the Direct Outokumpu Nickel or DON smelting process, which produces high-grade Ni matte with low Fe directly in the flash smelting furnace with metal values from the smelting slag recovered to Fe-containing Ni matte by laundering in the electric furnace. As expected, adoption of the process improved environmental conditions but the low melting points of the high-grade low-Cu mattes brought challenges for thermal engineering of the furnace hearth. Key issues of the technology are processing of high-magnesia concentrates and recoveries of Ni, Cu, Co and PGE, all affected by process selection and operational conditions. Modern computational tools can quickly obtain reliable new data on the phenomena occurring in the smelting vessels, complementing or even replacing laboratory, pilot or industrial experiments: examples presented include modelling of high-MgO concentrate smelting, bottom cooling and combustion. Injection of concentrates or coke is used to control the level of sulphurisation or to accelerate the reduction process., In 1995 Ni production capacity at Harjavalta was increased from 17 000 t/a to 52 000 t/a by replacing Peirce-Smith converting, in use since 1959, with the Direct Outokumpu Nickel or DON smelting process, which produces high-grade Ni matte with low Fe directly in the flash smelting furnace with metal values from the smelting slag recovered to Fe-containing Ni matte by laundering in the electric furnace. As expected, adoption of the process improved environmental conditions but the low melting points of the high-grade low-Cu mattes brought challenges for thermal engineering of the furnace hearth. Key issues of the technology are processing of high-magnesia concentrates and recoveries of Ni, Cu, Co and PGE, all affected by process selection and operational conditions. Modern computational tools can quickly obtain reliable new data on the phenomena occurring in the smelting vessels, complementing or even replacing laboratory, pilot or industrial experiments: examples presented include modelling of high-MgO concentrate smelting, bottom cooling and combustion. Injection of concentrates or coke is used to control the level of sulphurisation or to accelerate the reduction process.

Operations of a direct-to-blister copper flash smelting furnace (FSF) were compared with those of a conventional FSF using computational fluid dynamics. The simulation used Fluent CFD code, together with the Outokumpu Flash model. The concentrate feed to the direct-to-blister furnace was produced by the Outokumpu concentrate upgrade process, while the conventional furnace treated a normal copper concentrate. The results showed that the capital costs of changing from matte making to blister making in an existing FSF were small compared with the large gain in treatment capacity (153 000 tonnes/year to 455 000 tonnes/year). There would be a reduction in operating costs as converters were no longer required, and it would be possible to use the existing acid plant., Operations of a direct-to-blister copper flash smelting furnace (FSF) were compared with those of a conventional FSF using computational fluid dynamics. The simulation used Fluent CFD code, together with the Outokumpu Flash model. The concentrate feed to the direct-to-blister furnace was produced by the Outokumpu concentrate upgrade process, while the conventional furnace treated a normal copper concentrate. The results showed that the capital costs of changing from matte making to blister making in an existing FSF were small compared with the large gain in treatment capacity (153 000 tonnes/year to 455 000 tonnes/year). There would be a reduction in operating costs as converters were no longer required, and it would be possible to use the existing acid plant.

Copper droplet settling performance in the settler of a flash smelting furnace was simulated using a Langrangian method. Calculations were carried out for cases with and without slag tapping. The effects of slag taphole locations, tapping velocities and droplet sizes were investigated. The results showed that both the taphole location and the tapping velocity have a significant effect on droplet settling behaviour and that different droplet sizes demonstrate different settling behaviour. Most of the droplets with a diameter less than about 100 micrometres did not settle into the matte layer. In the absence of slag tapping, natural convection in the slag caused by the heat transfer from the furnace wall and the slag-matte interface was very weak and the predicted settling time was greater than that obtained according to Stokes' law. With slag tapping, only droplets around the taphole were entrained into the hole. In the sidewall taphole arrangements considered, it appears that the taphole is located far enough from the reaction shaft. Higher slag tapping velocity may entrap more Cu droplets, resulting in increased Cu losses in the slag., Copper droplet settling performance in the settler of a flash smelting furnace was simulated using a Langrangian method. Calculations were carried out for cases with and without slag tapping. The effects of slag taphole locations, tapping velocities and droplet sizes were investigated. The results showed that both the taphole location and the tapping velocity have a significant effect on droplet settling behaviour and that different droplet sizes demonstrate different settling behaviour. Most of the droplets with a diameter less than about 100 micrometres did not settle into the matte layer. In the absence of slag tapping, natural convection in the slag caused by the heat transfer from the furnace wall and the slag-matte interface was very weak and the predicted settling time was greater than that obtained according to Stokes' law. With slag tapping, only droplets around the taphole were entrained into the hole. In the sidewall taphole arrangements considered, it appears that the taphole is located far enough from the reaction shaft. Higher slag tapping velocity may entrap more Cu droplets, resulting in increased Cu losses in the slag.

The present modelling activities on flash smelting at the Helsinki University of Technology are introduced. A flash smelting furnace geometry was simulated in 2- and 3-D laboratory models, which were in turn modelled by using commercial computational fluid dynamics CFD2000 software and extended to an industrial-scale furnace and waste heat boiler. The work has proceeded from cold gas flow to heat transfer, combustion and two-phase flow simulations. The modelling task has been divided into sub-models: the concentrate burner, the reaction shaft with part of the settler, the uptake shaft with the rest of the settler and the waste heat boiler. The main results and some validation measurements are presented., The present modelling activities on flash smelting at the Helsinki University of Technology are introduced. A flash smelting furnace geometry was simulated in 2- and 3-D laboratory models, which were in turn modelled by using commercial computational fluid dynamics CFD2000 software and extended to an industrial-scale furnace and waste heat boiler. The work has proceeded from cold gas flow to heat transfer, combustion and two-phase flow simulations. The modelling task has been divided into sub-models: the concentrate burner, the reaction shaft with part of the settler, the uptake shaft with the rest of the settler and the waste heat boiler. The main results and some validation measurements are presented.

A commercial computational fluid dynamics code was used to solve isothermal flow fields of gas and liquid in a Peirce-Smith converter. The model was validated with a quarter-scale water model and parametric study. Limits of the modelling technique used were recognised, but calculated results indicate that the model predicts the general flow field with reasonable accuracy. The model was used to examine general flow conditions in an industrial scale Peirce-Smith converter. Typical scaling factors of physical models were also evaluated with the aid of predicted bubble distribution, patterns of the flow fields and magnitude of flow velocities., A commercial computational fluid dynamics code was used to solve isothermal flow fields of gas and liquid in a Peirce-Smith converter. The model was validated with a quarter-scale water model and parametric study. Limits of the modelling technique used were recognised, but calculated results indicate that the model predicts the general flow field with reasonable accuracy. The model was used to examine general flow conditions in an industrial scale Peirce-Smith converter. Typical scaling factors of physical models were also evaluated with the aid of predicted bubble distribution, patterns of the flow fields and magnitude of flow velocities.

A model is presented for simulating the oxidation reactions of chalcopyrite particles, together with momentum, heat and mass transfer between particle and gas phase in a flash smelting furnace reaction shaft. The equations governing the gas flow are solved numerically with a commercial fluid flow package, Phoenics. The particle phase is introduced into the gas flow by a particle source in cell technique. The chemical reactions of concentrate particles are assumed to happen at two sharp interfaces, and the shrinking core model is applied to describe the mass transfer of chemical species through the reaction product layer., A model is presented for simulating the oxidation reactions of chalcopyrite particles, together with momentum, heat and mass transfer between particle and gas phase in a flash smelting furnace reaction shaft. The equations governing the gas flow are solved numerically with a commercial fluid flow package, Phoenics. The particle phase is introduced into the gas flow by a particle source in cell technique. The chemical reactions of concentrate particles are assumed to happen at two sharp interfaces, and the shrinking core model is applied to describe the mass transfer of chemical species through the reaction product layer.

A computational fluid dynamics (CFD) study was carried out of a three-dimensional magneto-hydrodynamic flow for an industrial-scale slag cleaning furnace with three electrodes immersed into the slag using idealised and actual electrode shapes. The trajectories of Ni droplets were calculated to show the potential areas for droplet settling. Calculations were also carried out for varied boundary conditions along the free surface of the slag and the furnace wall. Electrode shape had some effect on slag flow and metal droplet settling. The slag temperature decreases with an increase in the heat loss rates from the slag surface and the furnace wall. It is important to present correctly the boundary conditions at the free surface and the furnace wall in order to obtain reasonable predictions for the slag flow and heat transfer. The numerical predictions were validated using experimental data from an operating slag cleaning furnace at Outokumpu, Finland., A computational fluid dynamics (CFD) study was carried out of a three-dimensional magneto-hydrodynamic flow for an industrial-scale slag cleaning furnace with three electrodes immersed into the slag using idealised and actual electrode shapes. The trajectories of Ni droplets were calculated to show the potential areas for droplet settling. Calculations were also carried out for varied boundary conditions along the free surface of the slag and the furnace wall. Electrode shape had some effect on slag flow and metal droplet settling. The slag temperature decreases with an increase in the heat loss rates from the slag surface and the furnace wall. It is important to present correctly the boundary conditions at the free surface and the furnace wall in order to obtain reasonable predictions for the slag flow and heat transfer. The numerical predictions were validated using experimental data from an operating slag cleaning furnace at Outokumpu, Finland.

A general-purpose program for modelling fluid flow, heat transfer and chemical reactions, PHOENICS, was adapted to pyrometallurgical processes as part of a project to develop a tool for optimising the energy efficiency of flash smelting. Subprograms were added which combined existing theoretical and experimental knowledge of sulphide combustion. A flash smelting furnace and the waste heat boiler at Harjavalta were simulated to give data such as particle temperature as a function of reaction time for different particle sizes, particle trajectories with gas temperature profile and SO2 mass fractions in the upper part of the reaction shaft, and gas velocity and temperature profiles at the centreline in the old and new waste-heat boilers. The package proved suitable for development even in a PC environment., A general-purpose program for modelling fluid flow, heat transfer and chemical reactions, PHOENICS, was adapted to pyrometallurgical processes as part of a project to develop a tool for optimising the energy efficiency of flash smelting. Subprograms were added which combined existing theoretical and experimental knowledge of sulphide combustion. A flash smelting furnace and the waste heat boiler at Harjavalta were simulated to give data such as particle temperature as a function of reaction time for different particle sizes, particle trajectories with gas temperature profile and SO2 mass fractions in the upper part of the reaction shaft, and gas velocity and temperature profiles at the centreline in the old and new waste-heat boilers. The package proved suitable for development even in a PC environment.