A cleaner method for preparation of chromium oxide from chromite ore

To establish a cleaner production technology of chromium salt, the pressurized leaching process of chromite ore in 60 wt% NaOH solution, subsequent separation of a chromium salt from the leached solution and Cr2O3 preparation from the intermediate product BaCrO4 were systematically investigated, and a new highly efficient and economical process for the production of Cr2O3 from chromite ore was established. The results showed that the decomposition of chromate ore could be significantly improved by increasing the temperature, and the Cr leaching rate reached 99% at 240 degrees C for 4 h. Meanwhile, the leaching process was controlled by surface chemical reactions with activation energy (Ea) of 34.3051 kJ/mol and a pre-ex-ponential factor (A) of 6.9560. In the leached liquor, Na2CrO4 was transformed into BaCrO4 through its reaction with Ba(OH)(2), Cr separation efficiency could reach as high as 89% in the undiluted leached liquor, while the separated alkali liquor could be effectively recycled for the leaching of chromite ore. Ultimately, a new method for the preparation of Cr2O3 from the intermediate product BaCrO4 was presented by the dissolution and reduction of BaCrO4 with HCl-CH3CH2OH as the reactant. The new cleaner process for Cr2O3 preparation from chromite ore provides an attractive alternative to upgrading the current chromate salt production processes. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Automated summary

A new highly efficient and economical process for the production of Cr2O3 from chromite ore was established by investigating the pressurized leaching process, chromium salt separation, and Cr2O3 preparation from BaCrO4. The new method significantly improved Cr leaching rate and separation efficiency, while also enabling the recycling of alkali liquor during the leaching process.