The Characterization of Residues Related to the Roasting– Leaching–Electrowinning Zinc Production Route for Further Metal Extraction
2024 (English)In: Metals, ISSN 2075-4701, Vol. 14, no 1, article id 73Article in journal (Refereed) Published
Abstract [en]
Super-hot acid leach residue is generated during zinc production in the roasting–leaching–electrowinning route, where both primary and secondary resources are used as feed material. This residue may contain valuable metals, such as lead, zinc, and iron, as well as precious metals, such as gold and silver. Four materials, namely super-hot acid leach residue, a residue formed when super-hot acid leach residue is selectively leached for lead with triethylenetetramine, as well as flotation concentrate, and flotation tailings formed in a selective silver flotation process with super-hot acid leach residue as the feed material were characterized to obtain a deeper understanding of possible further metal extraction. These four materials were characterized for chemical composition, mineralogy, and mineral distribution via chemical analyses, X-ray diffraction, and energy-dispersive scanning electron microscopy, respectively. The scanning electron microscope images showed that the materials have large variations in particle size distribution and composition. The results showed that the main lead phase in super-hot acid leach residue is lead sulfate, whereas it is mostly converted to lead sulfide during the selective lead leaching of the super-hot acid leach residue. The remaining lead sulfate is found in a solid solution with barium sulfate. Extracting lead from super-hot acid leach residue via triethylenetetramine leaching resulted in increased concentrations of gold and silver by 41% and 42%, respectively. The identified silver phases in super-hot acid leach residue may correspond to silver sulfide, silver chloride, and elementary silver, where silver sulfide was the most commonly occurring silver phase. After leaching this selectively for lead with triethylenetetramine, similar silver phases were identified, but silver sulfide and silver chloride occurred to a similar extent. Additionally, silver copper sulfide was detected. The presence of different silver phases might pose a challenge to reaching high silver recovery during leaching as the optimum leaching conditions differ somewhat. Furthermore, elemental sulfur, with a tendency to coat gold and silver particle surfaces, which is indicated to be present in all materials except the silver flotation tailings, may hinder metal extraction.
Place, publisher, year, edition, pages
Multidisciplinary Digital Publishing Institute (MDPI) , 2024. Vol. 14, no 1, article id 73
Keywords [en]
characterization for metal extraction, residue recycling, silver identification, super-hot acid leaching, zinc leaching residues
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
URN: urn:nbn:se:ltu:diva-104168DOI: 10.3390/met14010073Scopus ID: 2-s2.0-85183369013OAI: oai:DiVA.org:ltu-104168DiVA, id: diva2:1834505
Note
Validerad;2024;Nivå 2;2024-02-05 (joosat);
Funder: EIT Raw Materials, co-funded by European Union (19164); Boliden Mineral AB;
Full text license: CC BY
2024-02-052024-02-052024-02-05Bibliographically approved