Abstract
Laterite ore leaching to recover nickel and cobalt using high-temperature sulfuric acid has been described in this chapter. This process of leaching is termed as high-pressure acid-leaching process or HPAL process, which is highly selective to nickel and cobalt. A pressure leaching autoclave is used in this process that receives the hot feed slurry through positive displacement slurry pump and maintains the slurry residence time between one and two hours. Pressure leaching autoclave operates at 6 bar above the vapor pressure of the slurry by means of air addition and kept in steady-state operation through various means. During pressure leaching, measurements like slurry temperature, which is measured using thermocouples, slurry level, which is measured with a nuclear or radar level detector, and sulfuric acid concentration, which is measured using pH sensor, are recorded. Due to high amount of iron, scales are formed on the autoclave walls during pressure leaching. However, this scale formation can be controlled by maintaining low levels of aluminum, magnesium and sodium concentrations in the feed. After the slurry is sent to flash tanks from the autoclave, these flash tanks reduce the pressure of the slurry to atmospheric pressure level and the slurry is cooled, neutralized, to precipitate nickel and cobalt. The composition of the feed slurry, the chemical reactions of nickel and cobalt leaching, and fate of iron during leaching has been explained. Overall, laterite leach plants have recorded good performance.
Sign-in/Register to access full text options 
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 callMore From: Extractive Metallurgy of Nickel, Cobalt and Platinum Group Metals
Disclaimer: 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.
