TY - GEN

T1 - Halides - Associated problems during the primary zinc production process

AU - Benigni, Caterina

AU - Patscheider, Stefan

AU - Pichler, Christoph

AU - Antrekowitsch, Jürgen

PY - 2016/11/30

Y1 - 2016/11/30

N2 - Recycling of zinc containing residues takes place nowadays in Waelz kilns that generate a secondary zinc oxide for the primary zinc industry. Rising complexities of the feeded materials cause a zinc product that is loaded with undesirable elements such as fluorine and chlorine. To reduce the halide content an additional washing step is necessary. To keep the metal loss low soda is charged during washing to create an insoluble metal carbonate and a soluble sodium salt. The alkaline conditions have an impact on the removal of fluorine as well. The target values for halides in the zinc electrolysis are max. 100 mg/L for chlorine and max. 50 mg/L for fluorine. In most cases the washing step is not able to decrease the halides to such low values and therefore, the secondary zinc oxide runs through the whole zinc primary process. The present paper deals with the state of the art soda washing process as well as with alternative possibilities to reduce the halide content to use it directly in the leaching stage.

AB - Recycling of zinc containing residues takes place nowadays in Waelz kilns that generate a secondary zinc oxide for the primary zinc industry. Rising complexities of the feeded materials cause a zinc product that is loaded with undesirable elements such as fluorine and chlorine. To reduce the halide content an additional washing step is necessary. To keep the metal loss low soda is charged during washing to create an insoluble metal carbonate and a soluble sodium salt. The alkaline conditions have an impact on the removal of fluorine as well. The target values for halides in the zinc electrolysis are max. 100 mg/L for chlorine and max. 50 mg/L for fluorine. In most cases the washing step is not able to decrease the halides to such low values and therefore, the secondary zinc oxide runs through the whole zinc primary process. The present paper deals with the state of the art soda washing process as well as with alternative possibilities to reduce the halide content to use it directly in the leaching stage.

KW - product quality

M3 - Conference contribution

SP - 149

EP - 154

BT - OPMR - Opportunities in processing of metal resources in South East Europe

ER -