Identification of the significant factors determining extractability of Ni and Cu after sulfation roasting of a PGM-bearing chromitite ore

Metal recycling is drawing high interest in the context declining natural resources and the future circular economy. Smelter dust from copper extraction plants contains copper (Cu), which is both an economic loss and a pollution issue. There is therefore a need for techniques to recover Cu from ultrafine dust. Here we tested sulfation roasting, water leaching and electrorefining to recover Cu. We studied this process by thermochemical simulation and thermogravimetry to optimize sulfation roasting parameters such as time, temperature and quantity of sulfuric acid. Results show that copper can be selectively recovered as 99.9% of pure copper. Moreover, we recycled chemicals by-products of the plant in the process. Our findings suggest that this process is upscalable and should decrease the environmental pollution by Cu.

High-purity copper recycled from smelter dust by sulfation roasting, water leaching and electrorefining

Pyrometallurgical processing of a low copper content concentrate based on a thermodynamic assessment

Platinum Group Metals (PGMs), often with associated gold, have very few occurrences where they are present in an ore deposit at economically extractable levels. They are classified as both precious and critical metals due to their scarcity and their wide industrial use. With deteriorating socio-political environments in most primary PGM producing countries, PGM deposits that are smaller but in less risky jurisdictions have to be evaluated. However, the lower PGM grades, increased mineralogical complexity of the ores, capital intensity and strict environmental regulations in other international jurisdictions, limit the implementation of conventional metallurgical processing options, particularly smelter-based operations. The conventional smelter-based process options are justifiable for high grade, low chromite, large resource and long life-of-mine operations. In the present paper, we review some of the most recent literature on the predominantly hydrometallurgical approaches to PGM extraction. A number of metallurgical processes that generate either a PGM rich leachate or a residue containing metal values, and the various methods in use for their recoveries from pregnant rich solutions are reviewed. Sixteen process flowsheet variants combining conventional and proprietary unit process technologies are provided, and their process chemistries and key technical operating parameters are compared. Where appropriate, the key thermodynamic and kinetic factors are given and compared. 2015 Elsevier Ltd. All rights reserved.

Extraction of PGMs from Low-grade Oxide Mineral Deposits

The ancient flotation tailings from Lefke, Cyprus, have a potential for non-ferrous metals such as cobalt and copper from more than 9.5 million tons of reserves containing 0.38% Cu, 0.032% Co, and 22.6% Fe. Recovery of cobalt and copper from these tailings can provide great benefits from economic and environmental perspectives. While the ancient tailings were kept long time in storage in dumps, the characteristics of the material has become different from the common Co and Cu bearing ores. In order to extract these valuable metals, a process involving combination of roasting and leaching was applied in this study. Since this process responded to recovery to some extent, an innovative technique of using Na2SO4 as a promoter during roasting was proposed. Utilizing of Na2SO4 did not provide only higher metal extractions, but also resulted in high selectivity. In the scope of the study, following the determination of the mineralogy and chemical composition of the tailings, certain processes such as direct leaching and sulfation roasting with/without additives before leaching were applied. Since low metal extractions were obtained from direct leaching, a selective sulfation process was applied on the tailings before leaching in order to produce a pregnant solution containing higher amounts of Co and Cu metals by reducing the iron concentration. When sulfation roasting was performed without any additive, the desired selectivity could not be provided, since the sample was considerably oxidized under the atmospheric conditions in the past. Therefore, the usage of Na2SO4 as an additive with the amount of 25% at a roasting temperature of 700єC was tested. Consequently, Na2SO4 improved the sulfation and resulted in higher cobalt (90.1%) and copper (71.2%) recovery during leaching. Beside this, an improvement with a selective sulfation was obtained by combined effect of Na2SO4 addition and temperature, and the iron extraction decreased from 26.1% to 3.9%.

http://www.doiserbia.nb.rs/ft.aspx?id=1450-53391900043O

Cobalt and copper recovery from the ancient flotation tailings by selective sulfation roast - leaching process

Sulfation roasting was studied to extract copper from the copper sulfide concentrate. Sodium sulfite was added as sulfation agent to the copper sulfide concentrate during roasting in this study. Sulfur removal rate at different roasting temperatures was investigated, and the effects of roasting temperature, roasting time, and the amount of sodium sulfite on copper extraction were studied. Copper extraction higher than 96% was achieved at optimum roasting conditions.

https://www.scirp.org/journal/PaperDownload.aspx?downloadType=epub&paperID=53964

Recovery of Copper from Copper Sulfide Concentrate by Sulfation Roasting

Chlorination was used to extract gold, silver, copper, lead and zinc from gold concentrate. Parameters of J3 leaching agent (the patented reagents of the research group) concentration, acidity, NaCl concentration, leaching temperature were optimised. The extraction of gold, silver, copper, lead and zinc were 96.85%, 73.84%, 90.63%, 93.8% and 48.39% respectively at optimum conditions.

http://www.dpi-proceedings.com/index.php/dteees/article/download/31548/30143

Ya-nan Hou

Papers

Recovery of Copper from Copper Sulfide Concentrate by Sulfation Roasting

Preliminary Study on Comprehensive Recovery of Gold Concentrates by Chlorination