Separation of iron, nickel, and cobalt from sulphated leach liquor of low nickel lateritic oxide ore

A two-stage selective precipitation technique was developed for the separation of iron, nickel, and cobalt from sulphated leach liquor of nickeliferous lateritic oxide ore obtained from Sukinda Valley, Orissa, India. In the first stage of precipitation, solid CaCO3 is added to the sulphated solution at 90 to 95degreesC till the pH is adjusted in the range of 2.2 to 2.5. Most of the iron is precipitated out along with CaSO4. In the second stage, the residual iron and cobalt are separated from nickel by selective oxidation of cobalt. Bleaching powder and sodium oxychloride were separately used for this purpose. About 80 to 85% of the iron may be precipitated in the first stage, with practically no nickel or cobalt loss. Efficiency of iron precipitation in the first stage greatly depends on the initial iron concentration of the leach liquor. In the second stage, residual iron precipitation is complete along with 90% of total cobalt and 7 to 8% of total nickel