Abstract
In this paper, a scheme is proposed for the treatment of arsenic-containing lead slime by the combination of acid pressure oxidation leaching and forming scorodite. On the basis of thermodynamic calculations, the effects of six factors including acid concentration, oxygen partial pressure (pO2), liquid to solid ratio (L/S), agitating speed, leaching time and temperature for the removal of arsenic were studied in an acid pressure oxidation leaching process, then the optimum leaching conditions were established: L/S of 10 mL/g, leaching time of 2.5 h, pO2 of 2.0 MPa, leaching temperature of 170 °C, acid concentration of 100 g/L and stirring speed of 300 r/min. Under the optimal conditions, the leaching rate of arsenic from lead slime reached 99.10% and the arsenic content of the leaching residue was about 0.80%. After a decontamination procedure, the total arsenic concentration in the acid solution obtained from leaching experiments was 37.18 g/L, and the initial pH was 0.50. Finally, as high as 98.5% of arsenic extracted from the lead slime was stabilized in the form of scorodite (FeAsO4·2H2O) by the precipitation process under the following conditions: initial pH value of 1.0, Fe(II)/As molar ratio of 1.3, pO2 of 2.5 MPa, temperature of 160 °C and precipitation time of 2.0 h.
Highlights
Arsenic is volatilized and transferred in the process of pyrometallurgy, leading to the generation of all kinds of hazardous waste
The process scheme consists of three stages: the first stage is the leaching of lead slime, the second stage is the decontamination of leaching solution, and the third stage is the scorodite precipitation of arsenic in leachate [42]
Some research has investigated the effect of initial arsenic concentration on scorodite formation, and the results indicated that the high initial arsenic concentration was unfavorable for arsenic precipitation [43]
Summary
Arsenic is volatilized and transferred in the process of pyrometallurgy, leading to the generation of all kinds of hazardous waste. Hydrometallurgy, pyrometallurgy and volatilization pre-dearsenization followed by hydrometallurgy methods aiming to extract the valuable metals are usually used for reuse of high arsenic smelter ash [5,6]. Some waste, such as lead slime, will be generated in the reuse treatment of lead smelter ash, and will lead to secondary pollution [7]. The aim of the solidification process is to reduce the chance of the waste coming into contact with the environment by changing its physical properties [11] This is usually achieved by mechanically mixing the slime with additives to form a solid product [12].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
