Aluminum Removal from Leach Liquor of Nitric Acid Pressure Leaching Laterite Ores

Abstract

In this paper, the removal of aluminum in leach liquor of nitric acid pressure leaching laterite was investigated, and a new method of aluminum removal by precipitation with calcium sulphide was presented. The effect of reaction temperature, pH value before ageing and ageing time on the removal of aluminum were examined in details. The optimum conditions were determined as follows: reaction temperature 40 °C, pH 3.9~4.1 (before aging) and aging time 30 min. Compared with the traditional precipitation method, the loss of nickel and cobalt was less than 1% in the obtained aluminum precipitate slag, which is 3% lower than that by the traditional method; the filtration rate of aluminum precipitate slurry was faster than the traditional method, when the filtration press was controlled at -0.04 MPa, the filtration rate of aluminum precipitate slurry could reach 0.109 m3/(h•m2), which is 6.5 times higher than that obtained by the traditional method.