A novel process of extracting niobium, yttrium, and cerium from a low-grade niobium-bearing ore by the roasting (NH 4 ) 2 SO 4 -Na 2 SO 4 -H 2 SO 4 system was experimentally studied. The influences of various factors, such as roasting temperature, roasting time, mass ratio of agents-to-ore and particle size fraction on the extraction of valuable metals were comprehensively investigated. It is found that the roasting Na 2 SO 4 -H 2 SO 4 system is effective to extract the niobium, yttrium, and cerium. The obtained optimum conditions for the extraction of Nb, Y, and Ce are roasting temperature of 300°C, roasting time of 3 h, mass ratio of Na 2 SO 4 :H 2 SO 4 :Ore of 0.5:1.0:1.0, and particle size fraction of -74 lm (*95 %). Under the optimum condition, the maximum recovery of Nb, Y, and Ce can reach 90.53 %, 92.15 %, and 98.04 %, respectively. All the results generated from this study will provide the fundamentals for Nb, Y, and Ce extraction from a niobiumbearing ore with low-grade.
The microorganism trench-leaching process of a low-grade uranium ore with a high content of fluorine was experimentally studied through the technique of Real-time PCR by using the fluorine-tolerance bacteria of Retech-3 as the leaching-ore bacteria. It was found that the Retech-3 strains of fluorine-tolerance domestication grown well in a fluoride solution with concentration of 0.0~3.0 g·L-1, and the oxidation of Fe2+ ions to Fe3+ ions occurred rapidly to promote the extraction of uranium. The experimental results showed that the bioleaching rate (89.82%) of uranium can be improved of 13.80% than acid leaching in 30 days with 65 kg ore and its particle size of-6 mm (fraction of 100%) in trench. The Real-time PCR analysis of microbial population compositions revealed that Retech-3 strains were mainly composed of Leptospirillum sp. and Acidithiobacillus sp. in the leaching process. The obvious improvements of fluorine-tolerance domestication of bacteria and the uranium leaching process will provide fundamentals for the smooth utilization of a high fluorine-containing uranium ore with the aid of microorganism trench-leaching.
Iron ore is the raw material for steel production, in addition to iron and slag major component, still contains sulfur and phosphorus compounds and other harmful elements, is the potential adverse effects of factors constitute the steel product quality and environment. Sulfur in iron ores into the steel products will not only produce "heat brittle" phenomenon, but also in the sintering process by roasting produce sulfur dioxide into the air, causing damage to the atmosphere and ecological environment. A typical of the high sulfur iron ore from Inner Mongolia, China, iron grade of 53.06% and sulfur content is 2.76%, the main metal mineral in the ore is magnetite, followed by magnetic pyrite, pyrite and siderite, otherwise a small amount of copper mineral chalcopyrite, bornite. In this work, a mixed culture composed by Sulfobacillus thermotolerans, Leptospirillum ferriphilum and Ferroplasma acidiphilum was used to leach the sulfur in iron ore samples, we investigated the leaching rate of sulfur under different initial pH, temperature and pulp density conditions. The results showed that under the condition of the initial pH of 1.8, the temperature was 33 °C, and pulp density 15%, after 7 days of oxidation, we got a yield of 80.16% product in which iron grade of 62.31% and sulfur content is 0.17%. Compared with original sample, sulfur content decreased 95.06%, iron grade increased by 9.25%, and iron recovery was 94.13%. From the results it can be concluded that this microbial process for high sulfur iron ore lead to a significant effect of sulfur reduction and substantial increase in iron grade.
In this work, the monitoring of bacterial and chemical dissolution of massive bornite was performed using cyclic voltammetry (CV); the mineral surface was examined using scanning electron microscopy (SEM) and the elements were indentified by Energy Dispersive X-ray Analysis (EDXA). The electrolyte employed for the electrochemical tests was the medium used for bioleaching the electrodes (3.0 g•dm-3 (NH4)2•SO4, 0.5 g•dm-3K2HPO4, 0.5 g•dm-3 MgSO4•7H2O and 0.1 g•dm-3 Ca(NO3)2).The results showed differences in voltagramms carried out by Acidithiobacillus ferrooxidans and Acidithiobacillus caldus: In bioleached electrodes tested in the presence of Acidithiobacillus ferrooxidans, the anodic and cathodic current signals were larger than with Acidithiobacillus caldus The analysis of CV results allowed attributing the different peaks observed in both the direct and reverse potential scanning to the oxidation of bornite to a secondary copper mineral(chalcocite and covellite) and its reduction via different non stoichiometric copper sulphides intermediaries. Surface evidences were produced by SEM, and chemical elements evidences were also investigated by EDAX.
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.