中国有色冶金

Regarding MHP obtained from lime milk precipitation, this paper studies the process of MHP acid leaching with sulfuric acid as the leaching agent and neutralization of post-leaching solution by MHP based on its alkaline features. The paper also investigates the impact of the temperature, end point pH and MHP holding time on the leaching behavior of Ni, Co and Mn during acid leaching of MHP. The results show that leaching rates of Ni, Co and Mn in MHP reach 9950%, 9884% and 3858% respectively, with acid leaching performed at a temperature of 85℃, end point pH of 10 and MHP holding time for 3 days. To prevent Co in MHP and Mn in manganese hydroxide from being exposed to the air for a long time and thus oxidized, enhance the leaching rate of Co and Mn and reduce the amount of added reductant, MHP obtained from pressure filtration shall be subjected to acid leaching process after direct slurrying during the industralized production. Meanwhile, this paper studies the impact of the temperature and end point pH on the metal leaching rate during the neutralization of fresh MHP. It is found that Ni, Co and Mn leaching rates don’t change significantly, which reach 995%, 985% and 75% respectively, when the temperature is between 70℃ and 80℃ and the end point pH is 20 to 30. This process can realize efficient leaching of Ni and Co and selective leaching of Mn in MHP, which can provided a reference for nickel laterite project with full-process preparation of nickel sulfate by hydrometallurgical process.