Recovery of nickel and cobalt from laterites by sonic assisted sulfatation

Abstract

There is thus provided a method allowing the recovery of metallic values from laterites by the action of rather diluted sulfuric acid on nickel and cobalt-bearing laterites, at atmospheric pressure and near ambient temperature, assisted by ultrasonic treatment. With an acid concentration in the range for example between about 25 and about 50 weight % of sulfuric acid, under atmospheric pressure, sonication, extracting metallic values from the slurried laterites is thus achieved at room temperature.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims benefit, under 35 U.S.C. §119(e), of U.S. provisional application Ser. No. 61 / 968,029, filed on Mar. 20, 2014. All documents above are incorporated herein in their entirety by reference.FIELD OF THE INVENTION[0002]The present invention relates to a method and a system for recovery of nickel and cobalt from laterites. More specifically, the present invention is concerned with a method and a system for recovery of nickel and cobalt from laterites by sonic assisted sulfatation.BACKGROUND OF THE INVENTION[0003]Laterites can be defined as a variety of sub-soil, much weathered in tropical or subtropical climates, and containing iron oxides, alumina, silicates and, in some instances, small amounts, in percent range, of nickel along with traces of cobalt. Weathering over ages of this type of materials has created a segregation of metallic content, high concentration of iron under the form of limonite being found near the s...

AI Technical Summary

Benefits of technology

The present invention provides a method for recovery of metallic values from laterites by slurrying them in sulfuric acid, sonicating them and filtering them. This method can be specifically applied for recovery of nickel and cobalt from laterites by leaching them with sulfuric acid under sonication. The technical effects of this invention include higher efficiency and greater recovery of valuable metallic values from laterites.

Problems solved by technology

This method, typically used in Cuba, Australia and Brazil, is characterized by a very high energy consumption, in particular due to the need of drying of laterite and of reduction, and yields modest recovery, typically 75-85% for nickel and 45-55% for cobalt.

But operation of the method can be rendered very difficult or even impossible if the starting ore is rich in magnesium or free silica.

Scaling problems in the autoclave result from the presence of these substances that are of frequent occurrence in laterites.

Also, the PAL method for Ni / Co extraction from laterites is very capital expensive because of the high cost incurred by material requirements, especially autoclave inert to sulfuric acid at high temperatures.

Therefore, from the current practice worldwide, it appears that sulfuric acid is the desirable reagent for leaching nickel and cobalt from laterite but it is also obvious that the use of this reagent calls for relatively expensive equipment.

Equally limitative is the adverse effect of the presence of magnesium and free silica in the laterites, a situation that precludes the use of laterites with high magnesium / silica content but otherwise rich in nickel and cobalt.