The potential future usage of Boliden Harjavalta Oy copper and nickel slags

1. The potential future usage of Boliden Harjavalta Oy copper and nickel slags Virpi Leinonen University of Oulu

2. Main targets To find out and eliminate the limiting factors to utilisation of the investigated residues (copper and nickel slag) Search new feasible utilisation targets and end users residues categorised as wastes by the authorities if we get the slags to utilisation level we have to have also user for it residues categorised as wastes by the authorities if we get the slags to utilisation level we have to have also user for it

3. Residue rates and utilisation Copper slag from copper smelter (slag enrichment by flotation) 377 000 t/a, dumping Granulated slag from nickel smelter (slag processed by electric furnace) 127 000 t/a, dumping 45 000 t/a, utilisation Copper slag: dumping to the landfill in the factory area dumped as a slurry from the flotation; so the material is wet and its grain size is very fine Granulated slag: residue nickel from the slag is reduced by coke in the electric furnace before slag granulation mainly nickel slag is dumped quarter of slag is utilised in roofing felt industry and sand blasting Copper slag: dumping to the landfill in the factory area dumped as a slurry from the flotation; so the material is wet and its grain size is very fine Granulated slag: residue nickel from the slag is reduced by coke in the electric furnace before slag granulation mainly nickel slag is dumped quarter of slag is utilised in roofing felt industry and sand blasting

4. Copper smelter Copper slag: slag is formed in flash smelting furnace and n the converters so two different kind of slags are mixed in slag cooling stage converter slag consists more copper than flash furnace slag slag enrichment by flotation needs a fine grain size, which complicates the utilisation Arsenic: dissolution of arsenic limits utilisation of copper slag huge amount arsenic circulates in the process mainly arsenic is find from the internal dust circulation copper-rich dust from the gas cooling system is recycled back to the flash smelting furnace two times more arsenic is fed back to flash smelting furnace with the circulated dust than with feed mixture Copper slag: slag is formed in flash smelting furnace and n the converters so two different kind of slags are mixed in slag cooling stage converter slag consists more copper than flash furnace slag slag enrichment by flotation needs a fine grain size, which complicates the utilisation Arsenic: dissolution of arsenic limits utilisation of copper slag huge amount arsenic circulates in the process mainly arsenic is find from the internal dust circulation copper-rich dust from the gas cooling system is recycled back to the flash smelting furnace two times more arsenic is fed back to flash smelting furnace with the circulated dust than with feed mixture

5. arsenic is problematic from the environmental properties point of view because of its dissolution also pH is important effective element in the environmental acceptance pH affects to the solubility properties of material the status of hazardous waste complicates slags way to the utilisation few elements of copper slag exceed the dissolution limit set for normal waste so because of that copper slag is considered as hazardous waste arsenic is problematic from the environmental properties point of view because of its dissolution also pH is important effective element in the environmental acceptance pH affects to the solubility properties of material the status of hazardous waste complicates slags way to the utilisation few elements of copper slag exceed the dissolution limit set for normal waste so because of that copper slag is considered as hazardous waste

6. The obstacles to utilisation of the copper slag pH effects strongly to the dissolution properties of slag we are talking about by-product of process in the process is fed different kind of feeds so the composition changes are expected fine grain size: grind fine because of flotation enrichment at one time flotation enrichment selected to maximize copper recovery from slag status of hazardous waste: material requires environmental license for disposal and exploitation pH effects strongly to the dissolution properties of slag we are talking about by-product of process in the process is fed different kind of feeds so the composition changes are expected fine grain size: grind fine because of flotation enrichment at one time flotation enrichment selected to maximize copper recovery from slag status of hazardous waste: material requires environmental license for disposal and exploitation

7. Possibilities to affect and to promote the slag utilisation increasing arsenic outlets we reduce arsenic-level in the process and perhaps that way we can lower the arsenic level in the slag also by optimising slags mineralogy or by using additives arsenic can be bind insoluble form increasing arsenic outlets we reduce arsenic-level in the process and perhaps that way we can lower the arsenic level in the slag also by optimising slags mineralogy or by using additives arsenic can be bind insoluble form

8. Copper slag - way to the utilisation Arsenic: thermodynamic calculations to find out where precipitates in gas cooling system huge amount arsenic circulates in inter dust circulation Dust samples ? mass balance of arsenic in the copper production process possibilities to decrease arsenic level in the process by dust separation Dissolution ? had to know the environmental properties of the slag to have a permission to use slag/ utilize slag Control of dissolution properties ? in other words get the environmental properties fit in the authorities legislation Copper slag waste categorization has to be change before slag can be utilized Mineralogy ? mineralogy of copper compounds because of dissolution of arsenic from copper slag Arsenic crystallize mainly with the residual copper in the slag By controlling crystallization of the copper compounds in the slag can the dissolution be controlled also Cooling rate and additives are the possibilities to affect to the slag mineralogy vitrification at the time is thought to be an answer to the dissolution problems harmful elements can be immobilised to glass phase Quality management system part of the quality handbook of factory Evaluation ? copper slag not yet utilized: because of hazardous elements like arsenic; fine grain size If possible somehow to get the environmental properties to the level of orders of the authorities which are the utilization targets then introductions to users how to use new material Production changes: enrichment by flotation requires fine grain size of handled material, which problematic for utilisation alternative process could be for example electric furnace major effect would get by changing the enrichment process for example to electric furnace in Central Europe electric furnace based slags are widely utilized Arsenic: thermodynamic calculations to find out where precipitates in gas cooling system huge amount arsenic circulates in inter dust circulation Dust samples ? mass balance of arsenic in the copper production process possibilities to decrease arsenic level in the process by dust separation Dissolution ? had to know the environmental properties of the slag to have a permission to use slag/ utilize slag Control of dissolution properties ? in other words get the environmental properties fit in the authorities legislation Copper slag waste categorization has to be change before slag can be utilized Mineralogy ? mineralogy of copper compounds because of dissolution of arsenic from copper slag Arsenic crystallize mainly with the residual copper in the slag By controlling crystallization of the copper compounds in the slag can the dissolution be controlled also Cooling rate and additives are the possibilities to affect to the slag mineralogy vitrification at the time is thought to be an answer to the dissolution problems harmful elements can be immobilised to glass phase Quality management system part of the quality handbook of factory Evaluation ? copper slag not yet utilized: because of hazardous elements like arsenic; fine grain size If possible somehow to get the environmental properties to the level of orders of the authorities which are the utilization targets then introductions to users how to use new material Production changes: enrichment by flotation requires fine grain size of handled material, which problematic for utilisation alternative process could be for example electric furnace major effect would get by changing the enrichment process for example to electric furnace in Central Europe electric furnace based slags are widely utilized

9. Nickel smelter from the flash smelting furnace nickel slag flow is conducted to the electric furnace in the electric furnace residue nickel from the slag is reduced by coke before granulation after handling slag is granulated directly from electric furnace with water jets from the flash smelting furnace nickel slag flow is conducted to the electric furnace in the electric furnace residue nickel from the slag is reduced by coke before granulation after handling slag is granulated directly from electric furnace with water jets

10. Granulated slag

11. The obstacles to utilisation of granulated slag

12. Possibilities to affect and to promote the slag utilisation handling: wet sieving to get the fines out of end product and lower the dissolution of nickel handling: wet sieving to get the fines out of end product and lower the dissolution of nickel

13. Granulated slag – way to the utilisation Geotechnical properties: laboratory tests proved that granulated slag has good properties for road constructions and earthworks among others it is frost resistance material granulated slags main geotechnical properties are better than sand for road construction Evaluation ? slag’s technical properties has to be better than natural material More tests is required for wastes than to products Hopefully some property that is better than in natural material ? after that the slag easier to sell Competing materials with the slag ? rubber granules and sand by-products from different industry areas (fly ash, fibre clay…) scrap glass Experimental period: building experimental road we get the information of slags properties and resistance Coating the dumping areas ? new legislation comes into operation soon and on year 2007 a big amount of old landfills has to be closed and a lots of materials is needed in the coating work of those landfills innovative planning for utilisation of slag gives possibilities to wider targets and needed material amounts Productisation: almost only possibility to get slag on wider use Geotechnical properties: laboratory tests proved that granulated slag has good properties for road constructions and earthworks among others it is frost resistance material granulated slags main geotechnical properties are better than sand for road construction Evaluation ? slag’s technical properties has to be better than natural material More tests is required for wastes than to products Hopefully some property that is better than in natural material ? after that the slag easier to sell Competing materials with the slag ? rubber granules and sand by-products from different industry areas (fly ash, fibre clay…) scrap glass Experimental period: building experimental road we get the information of slags properties and resistance Coating the dumping areas ? new legislation comes into operation soon and on year 2007 a big amount of old landfills has to be closed and a lots of materials is needed in the coating work of those landfills innovative planning for utilisation of slag gives possibilities to wider targets and needed material amounts Productisation: almost only possibility to get slag on wider use

14. Potential of slags

15. Benefits from utilisation of the slags