Abstract
Lead-rich molybdenite is a typical rhenium-bearing molybdenum resource in China, which has not been efficiently utilized due to its high contents of lead and gangue minerals. In this study, hydrochloric acid was used for preliminarily removing lead and calcite from a lead-rich molybdenite concentrate. Oxidative roasting-ammonia leaching was then carried out for separation of rhenium and extraction of molybdenum. The hydrochloric acid leaching experiments revealed that 93.6% Pb and 97.4% Ca were removed when the leaching was performed at 95 °C for 10 min with HCl concentration of 8 wt. % and liquid-solid ratio of 5 (mL/g). The results of direct oxidative roasting indicated that 89.3% rhenium was volatilized from the raw concentrate after roasting at 600 °C for 120 min in air. In contrast, the rhenium volatilization was enhanced distinctly to 98.0% after the acid-leached concentrate (leaching residue) was roasted at 550 °C for 100 min. By the subsequent ammonia leaching, 91.5% molybdenum was leached out from the calcine produced from oxidative roasting of the acid-leached concentrate, while only 79.3% Mo was leached from the calcine produced by roasting molybdenite concentrate without pretreatment.
Highlights
Rhenium (Re) is an important metal that has been widely used in many fields, such as national defense, petrochemical engineering, aerospace, photovoltaics, solar cells, etc [1]
The volatilization of Re and leaching ratio of Mo in ammonia solution were improved significantly after the lead and calcium components in the raw material were removed by hydrochloric acid
The results of acid leaching show that 93.6% of Pb and 97.4% of Ca were removed under the conditions of 95 ◦ C for 10 min with HCl concentration of 8 wt. % and liquid-solid ratio of
Summary
Rhenium (Re) is an important metal that has been widely used in many fields, such as national defense, petrochemical engineering, aerospace, photovoltaics, solar cells, etc [1]. The global Re resource reached 2.5 million kg with only 48,800 kg produced in 2014. More than half of the production was from Chile, which has more than 1.3 million kg Re in reserves [2]. Rhenium is a rare metal occurring as rheniite (ReS2 ) mainly accompanying molybdenite. It was found in some copper, niobium yttrium iron, platinum and uranium ores. Copper or molybdenum sulfide concentrates via flotation circuits contain 50–100 g/t (ppm) Re [3]. Because of the high value of rhenium, recovering rhenium from molybdenum concentrate has received much attention
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