402
J. Salminen et al.
from LPG gas and coke, which is used in the reduction stage. About 5 wt% coke
addition was used in the feed for the final reduction stage. In the following test
works, the behaviour and efficiency of bio-coal and other non-fossil reductants will
be studied.
Conclusion
The idea of testing combined residue as a feed was at first seen as risky and challenging. The risks were foreseen in the slightly unknown dynamics of sulphur vaporization and reactions in the plasma furnace. First tests were indeed carried out with
jarosite after flotation that still contained significant amount of sulphur. Tests with
jarosite, including combined residue, containing variable sulphur content delivered
excellent results with slag composition and metal recoveries as desired. The CEN
leaching tests showed promising results as well. Only Sb content in the final slag was
slightly above inert landfill criteria. The results presented in this work look promising
and give technical confirmation that the process is feasible. The ArcFume process
was able to handle a feed with very high content of sulphur, being elemental sulphur, sulphate sulphur, as well as sulphides. Smelting only jarosite or neutral leach
residue is easier because smaller off-gas handling is required. The fuming stage that
follows the smelting is similar for all these cases. The results from the combined
residue tests however indicate that a separate fuming stage operated under reducing
conditions might not be necessary. Treating combined waste in a one-stage plasma
process is a possible solution for treating residues from zinc industry. Further investigations will be carried out using non-fossil reductants like bio-coal. The use of slag
in construction is also being studied.
References
1. Salminen J (2018) Overcoming challenges in the circular economy: a thermodynamic realitycheck. Socrates policy brief. www.socrates.com. Accessed 20 Aug 2019
2. Reuter et al (2019) Challenges of the circular economy: a material metallurgical and product
design perspective. Annu Rev Mat Res 49:253–274
3. Salminen J et al (2018) Challenges and possibilities in zinc residue treatment. Paper presented
at Extraction 2018. Ottawa, ON, 26–29 Aug 2018
4. Nyberg J (2019) Challenges for non-ferrous industry—less waste and recovering more metals.
Paper presented at Emc 2019 plenary lecture in Düsseldorf. ERZMETALL 72(3):158–166
5. Rämä M et al (2018) Thermal processing of jarosite leach residue for a safe disposable slag and
valuable metals recovery. Metals 8:744–748
J. Salminen et al.
from LPG gas and coke, which is used in the reduction stage. About 5 wt% coke
addition was used in the feed for the final reduction stage. In the following test
works, the behaviour and efficiency of bio-coal and other non-fossil reductants will
be studied.
Conclusion
The idea of testing combined residue as a feed was at first seen as risky and challenging. The risks were foreseen in the slightly unknown dynamics of sulphur vaporization and reactions in the plasma furnace. First tests were indeed carried out with
jarosite after flotation that still contained significant amount of sulphur. Tests with
jarosite, including combined residue, containing variable sulphur content delivered
excellent results with slag composition and metal recoveries as desired. The CEN
leaching tests showed promising results as well. Only Sb content in the final slag was
slightly above inert landfill criteria. The results presented in this work look promising
and give technical confirmation that the process is feasible. The ArcFume process
was able to handle a feed with very high content of sulphur, being elemental sulphur, sulphate sulphur, as well as sulphides. Smelting only jarosite or neutral leach
residue is easier because smaller off-gas handling is required. The fuming stage that
follows the smelting is similar for all these cases. The results from the combined
residue tests however indicate that a separate fuming stage operated under reducing
conditions might not be necessary. Treating combined waste in a one-stage plasma
process is a possible solution for treating residues from zinc industry. Further investigations will be carried out using non-fossil reductants like bio-coal. The use of slag
in construction is also being studied.
References
1. Salminen J (2018) Overcoming challenges in the circular economy: a thermodynamic realitycheck. Socrates policy brief. www.socrates.com. Accessed 20 Aug 2019
2. Reuter et al (2019) Challenges of the circular economy: a material metallurgical and product
design perspective. Annu Rev Mat Res 49:253–274
3. Salminen J et al (2018) Challenges and possibilities in zinc residue treatment. Paper presented
at Extraction 2018. Ottawa, ON, 26–29 Aug 2018
4. Nyberg J (2019) Challenges for non-ferrous industry—less waste and recovering more metals.
Paper presented at Emc 2019 plenary lecture in Düsseldorf. ERZMETALL 72(3):158–166
5. Rämä M et al (2018) Thermal processing of jarosite leach residue for a safe disposable slag and
valuable metals recovery. Metals 8:744–748