Papers by Keyword: Leaching Efficiency

Abstract: In the bioleaching process, many factors in ore, water and sediments are important contributors as driving forces to improve leaching efficiency. In this study, FeSO₄·7H₂O and S⁰ as energy substrates were added to an oxide-rich, low-grade copper ore to explore the influence of biological and environmental factors on leaching efficiency. Mantel test results showed that the leaching rate was significantly correlated with biological and environmental factors with r values of 0.78 and 0.63 respectively, indicating that influence of biological factors were more significant. It cannot be ignored that environmental factors were important to construct the microbial community. Real-time quantification polymerase chain reaction (RT-qPCR) showed that the dominant and minor species were A. caldus and A. ferrooxidans. Canonical correspondence analysis (CCA) made it clear that pH and ferrous concentration were crucial for shaping microbial community. All results are of great significant to gain the optimal leaching condition on Zambia oxide-rich, low-grade copper ore.

Abstract: In this paper, the influencing factors in the process of alkali leaching of refractory zinc oxidize ores were studied. The influence of the particle size, reaction temperature, leaching time, alkali concentration and liquid-solid ratio on the leaching efficiency of zinc were investigated via leaching tests. The results indicate that the particle size has little influence on the leaching efficiency of zinc while the influences of other factors are larger. The optimal leaching condition is: the reaction temperature is 80 °C, the alkali concentration is 4.5 mol/L, and the leaching time is 1.5 h as well as the liquid- solid ratio is 10:1. In such conditions, the leaching efficiency can reach 82.22%.

Abstract: Using pot experiment, the total arsenic absorbed by Pteris vittata L.from gold roe collected from Guizhou Xingren gold mine was investigated. Arsenic extraction efficiency and effects by five kinds of chelants such as Ethylene diamine tetraacetic acid disodium salt (EDTA-Na2), citric acid (CA), ammonium dihydrogen phosphate (MAP), Sodium bisulfite (NaHSO3) and Sodium bicarbonate (NaHCO3) were assessed. Absorption of As was measured in the fronds and roots of Pteris vittata L.under pot trial condition in which the tested gold ore powder was leached by the above five chelants with the concentrations of 0, 0.05, 0.1 and 0.15 mol•L-1, respectively. The results show that most of the chosen chelants can largely improve the efficiency of arsenic absorption. The leaching efficiency of As in fronds was generally listed in the following order: MAP>EDTA-Na2>CA>NaHCO3>NaHSO3 under the average concentration．With the increase of chelant concentration the As was extracted more and more on MAP and NaHCO3 . The extracting content of As ranged from 5055ug/g to 5974ug/g for EDTA, from3273 ug/g to 4975 ug/g for CA, from 7482 ug/g to 9357 ug/g for MAP and from 3620 ug/g to 5284 ug/g for NaHSO3, from 3401 ug/g to 6378 ug/g for NaHCO3, respectively. The leaching efficiency of As in roots was generally listed in the following order: MAP> NaHCO3>NaHSO3>EDTA-Na2>CA under the average concentration．The extracting content of As ranged from 1862ug/g to 2627ug/g for EDTA, from1494 ug/g to 2347 ug/g for CA, from 2739 ug/g to 3896 ug/g for MAP and from 2064 ug/g to 3373 ug/g for NaHSO3, from 2316 ug/g to 2587 ug/g for NaHCO3, respectively. These results mentioned above show that available As in Guizhou xingren gold mine can be most leached by Pteris vittata L.with the above chelants, especially in MAP treatment. MAP was the best chelants among the four tested chelants, suggesting that it will be useful in chelant-induced phyto-remediation.

Abstract: The run-of-mine of complex lead-zinc ores in Yunnan contains 3.26% lead and 2.54% zinc. When traditional selective flotation flowsheet was adopted, 3.77% yield and 61.92% grade of lead concentrate as well as 5.65% yield and 38.67% grade of zinc concentrate were achieved. Simultaneously, 72.39％ lead recovery and 3.83% zinc grade in lead concentrate as well as 80.64% zinc recovery and 6.39% lead grade in zinc concentrate were obtained. Lead concentrate and zinc concentrate obtained from selective flotation contain each other severely, resulting in low recovery of lead and zinc and severe loss of metal, which influences subsequent smelting flowsheet. In addition, due to requirement of large amount of depressant and activator while separating lead and zinc in the process of mineral processing, the cost is very high and the compositions of tail water which can not be recycled by the plant are very complicated. For the combined flowsheet of beneficiation and metallurgy, bulk flotation flowsheet was adopted. Therefore, 11.22% yield of combined lead and zinc concentrate with 25.55% lead grade, 18.33% zinc grade and 86.36% lead recovery were obtained. Gravity separation technology was utilized to separate combined concentrate of lead and zinc. After selecting out part of high quality lead concentrate, the remaining combined concentrate of lead and zinc was treated by acid leaching under high pressure. The final leaching efficiency of zinc was able to reach 97%. The new combined flowsheet has lots of advantages such as shorter flowsheet of beneficiation, simpler reagents, more direct reuse of backwater and higher recovery of metals.