Removal of Sb Impurities in Copper Electrolyte and Evaluation of As and Fe Species in an Electrorefining Plant

Antimony and arsenic concentrations and their oxidation states (Sb(III), Sb(V), As(III) and As(V)) in copper electrorefining electrolyte can affect copper cathode quality through the formation of floating slimes. A laboratory-scale pilot plant was operated to remove Sb from commercial electrolyte. The pilot plant consisted of a pre-treatment process with copper shavings followed by ion exchange. The results indicated that Sb(III) was removed from copper electrolyte completely, while Sb(V) was partially eliminated. The concentrations of As(III) and As(V) were not affected, and the poisoning of the ion exchange resin by Fe(III) was avoided by pre-reduction to Fe(II) by copper shavings. The operation configuration of the pilot plant was applied to the design of an industrial plant for Sb/Bi removal at the Atlantic Copper Refinery in Huelva, Spain. The evolution of Sb, Fe and As species in the commercial electrolyte was monitored prior to and after the installation of the Sb/Bi removal plant. The results show a ca. 45% decrease in total Sb content (from 0.29 g L−1 to 0.16 g L−1) in the electrolyte. This reduction is more noticeable for Sb(III), whose concentration decreased from 0.18 g L−1 to 0.09 g L−1, whereas Sb(V) concentration diminished from 0.11 g L−1 to 0.07 g L−1. The resin also retained ca. 75% of the Bi content (0.15–0.22 g L−1). The total As increased during the study period (from 7.7 to 9.0 g L−1) due to changes in plant inputs. Arsenic was predominantly As(V) (ca. 93–95%). The total Fe concentration experienced little variation (0.9–1.1 g L−1) with Fe(II) being the main species (ca. 94–96%)

Immobilization of Hazardous Wastes on One-Part Blast Furnace Slag-Based Geopolymers

: The immobilization of hazardous wastes in ordinary Portland cement (OPC)-based materials has been widely studied and implemented. OPC-based materials have a high carbon footprint associated with their production and geopolymer materials are a sustainable and eco-friendly alternative. Therefore, this work aimed to immobilize two hazardous industrial wastes: copper wastewater sludge and phosphogypsum in one-part geopolymer materials. For that purpose, the precursor was partially substituted by these wastes (5, 10 and 20 wt.%) in the formulations. The geopolymer fresh and hardened state properties were evaluated, and the immobilisation of pollutants was determined through leaching tests. In phosphogypsum pastes (PG5, PG10 and PG20) it was observed that the compressive strength decreased with the increase in its amount, varying between 67 MPa and 19 MPa. In copper sludge pastes, the compressive strength of the specimens (CWS5 and CWS10) reached ~50 MPa. The mortars, MPG10 and MCWSs10, had compressive strengths of 13 MPa and 21 MPa, respectively. Leaching tests showed that pastes and mortars immobilise the hazardous species of the wastes, except for As from copper sludge, whose the best result was found in the compact paste (CWSs10) that leached 2 mg/kg of As. Results suggest that optimized compositions are suitable for the construction sectorThis research was funded by Ministerio de Ciencia e Innovación (MICINN), grant number PID2020-116461RB-C21 and Agencia de Innovación y Desarrollo de Andalucía (IDEA) grant number UHU-1255876. This work was done in the scope of the project CICECO- Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, co-financed by national funds through the FCT/MEC. This research was funded by FCT (Portuguese Foundation for Science and Technology), grant number 2020.01135.CEECIND (R.M.N.) and SFRH/BD/144562/2019 (J.C.

Copper Flash Smelting Process Balance Modeling

Process control in flash smelting is based on mass and energy balance from which the operational parameters (oxygen coefficient, oxygen enrichment, and flux demand) are obtained to achieve matte and slag with defined compositions and at defined temperatures. Mineral compositions of copper concentrates, and their blends, have been used in order to optimize the heat process balance. The classical balance methodology has been improved by using equations for molecular ratios and distribution coefficients that have been calculated using FactSage™. This paper describes the development of balance equations and compares their theoretical (equilibrium) results with industrial data logs of the smelting process

Arsenic removal procedure for the electrolyte from a hydro-pyrometallurgical complex

Commercial copper (Cu) is obtained by a hydro-pyrometallurgical process, where the Cu anodes obtained in the furnaces (Cu > 99.5%) are enriched up to 99.99% in “cathodes” by electrorefining at an electrolysis plant. During this process, some impurities accumulate in the electrolyte, mainly arsenic (As), which decrease the quality of the Cu cathode. For this reason, the electrolyte is sent to an electrolyte cleaning plant (ECP) for its purification. Electrolyte sludge (ES) is produced in the last stage of purification and is recirculated back to the furnace due to the high Cu content. This recirculation involves a severe problem of As accumulation in the industrial process. The objective of this work was to develop a procedure to fully dissolve the ES, removing the As and recovering its Cu content. The ES dissolution process was optimised (dissolution efficiency > 99%) in H2SO4 (1.4 M)/HNO3 (1.8 M) medium using a 1:20 g mL-1 solid-to-liquid ratio. As was removed from the ES solution by its precipitation as iron (III) arsenate, with high efficiency (more than 70%). After As removal, the Cu can be precipitated as copper sulphate, which is used in several applications