A warm‐drawn Mg6Ag wire with a diameter of 1.6 mm is investigated by immersion tests in Ringer solution in two conditions: as‐drawn and solution heat‐treated wire. The initial as‐drawn condition showed higher strength in comparison to the solution heat‐treated one. As‐drawn wire has heavily twinned grains. Heat treatment causes slight grain growth, but less microgalvanic corrosion due to dissolved second phases and a significantly reduction of twin boundaries. The mean corrosion rate decreases by more than half by the heat treatment resulting in higher remaining mechanical properties. The mean corrosion rate also decreases with corrosion time, slightly more for the heat‐treated condition. Pitting corrosion was still present after solution heat treatment, although the pit shape is less harmful. The corroded wires and corrosion products were analysed qualitatively and quantitatively by SEM imaging and ICP‐OES with focus on the exposure time. Mg6Ag wires corrode under forming Mg(OH)2, CaCO3 and AgCl, SEM imaging proves higher corrosion resistance of heat‐treated Mg6Ag. Chemical analysis of wires, corrosion products and corrosion media offer to describe the time‐dependent mechanism.
Secondary hardmetal is a large part of the supply for new hardmetal products, yet the environmental impacts of hardmetal recycling remain unknown to a large degree. The goal of this study was to evaluate the gate-to-gate impacts of tungsten and cobalt recovery by chemical recycling. The LCI data was obtained from process simulations and the environmental impact categories were calculated using GaBi software. The simulations were used to study process performance and to investigate the effect of process parameter variation on the environmental impact indicators. Compared to primary production, chemical recycling decreased impacts by more than 50% in all investigated impact categories. The global warming potential for treating 1 metric ton of hardmetal scrap by standard chemical recycling to APT and Co(OH) 2 was 6121 kg CO 2 -eq., freshwater consumption 142 m 3 , eutrophication potential 2.3 kg P-eq., ozone depletion potential 0.0030 kg CFC-11-eq., acidification potential 91 kg SO 2 -eq., and photochemical ozone formation potential 11 kg NO x -eq. Process hotspots depended on the impact category of interest, but in most cases included oxidation of the scrap material and APT production. Major contributors to environmental impacts included electricity consumption, leaching chemicals, and heating required by the oxidation.
A simulation-based life cycle assessment was conducted to compare the impacts of different cyanide-free chloride processing routes for refractory ores to determine whether one-stage leaching of gold from the ores could be advantageous over chloride leaching after conventional pressure oxidation from an environmental perspective. It was shown that both leaching conditions and the refractoriness of the ore strongly affect the environmental impacts of the process. The global warming potential in the direct leaching route was determined to vary between 7.7-17.0 t CO 2 -eq for 1 kg gold/Au. Prerequisites for the sustainable application of the direct leaching process are suggested.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.