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Stirred-tank leaching of coarse-grained waste, printed circuit boards with Acidithiobacillus ferrooxidans

Fu Kaibin, Tian Li, Hou Puyao, Long Meiqiao, Chen Shu, Lin Hai

Physicochemical Problems of Mineral Processing

2021

Vol. 57, iss. 5

153--163

Stirred tank leaching of metals from coarse-grained waste, printed circuit boards (WPCB) used Acidithiobacillus ferrooxidans (A. ferrooxidans) at ambient temperature (20-35°C). The effect of the baffle size, WPCB concentration, and inoculation volume was tested. 95.92% of Cu, 93.53% of Al, 92.58% of Zn, 65.27% of Ni, and 95.33% of Sn in WPCBs were leached under the optimal conditions: no baffle, WPCB concentration of 5.0% (w/w), and inoculation volume of 5% (v/v). The alkaline substance and reactivity metal of WPCBs, and the oxidation of Fe2+, consume H+. Adding acid can maintain the pH value of the leaching solution, which is conducive to the growth and reproduction of the bacteria and improves the leaching efficiency of WPCBs. The second-order dynamics model can describe the acid consumption in the bioleaching process of coarse-grained WPCBs. Moreover, the Avrami equation can successfully explain the bioleaching kinetics of Cu, Al, Zn, Ni, and Sn from the coarse-grained WPCBs. The key factors controlling the bioleaching of coarse-grained WPCBs are metal reactivity and specific surface area. These results revealed that bioleaching metals from coarse-grained WPCBs using A.ferrooxidans is feasible, and has important significance to guiding its industrialization.

Preparation of ternary (35 – x)Sb2O3–xBi2O3–65P2O5 glasses for lead-free glass application

Li Yu-Ting, Zhang Jing-Jing, Wang Zhi-Qiang, Xu Fei-Long, Lin Hai

Materials Science Poland

2020

Vol. 38, No. 1

28--33

Glasses composed of ternary components (35 – x)Sb2O3–x Bi2O3–65P2O5 (0 ⩽ x ⩽ 20 mol%) have been prepared and investigated as a potential alternative to lead-free glass for low temperature applications. Their structural properties were studied by Infrared Spectroscopy IR and Differential Thermal Analysis DTA. Results from the IR showed that Sb3+ and Bi3+ were responsible for glass network structure, which was supported by the diversification of density ρ and molar volume Vm with an increasing amount of Bi2O3. Glass transition temperature Tg, thermal stability, and coefficient of thermal expansion increased after substitution of Bi2O3 for Sb2O3 within the range of 0 mol% to 20 mol%. The water durability decreased and then increased; it could be attributed to the corrosion resistant P–O–Sb bonds. A typical sample of 25Sb2O3–10Bi2O3–65P2O5 possesses excellent properties and can be a promising candidate for further applications.