Method of extracting lithium from low-clay minerals

A pyro-hydrometallurgical method for extracting lithium from complex clay minerals whose lithium-containing mineral compositions are in the ranges:

• orthoclase between 20 and 60%, quartz between 4 and 60%, calcite between 4 and 65%, clays between 2 and 35%, wherein the method comprises:
• (a) reducing the particle size with a ring mill for a period of between 10 and 60 minutes;
• (b) sieving the pulverized ore to a particle size between 0.074 and 0.149 mm;
• (c) dry-mixing the sodium sulphate-sifted ore, Na2SO4, in a mineral/Na2SO4 ratio ranging from 5:1 to 5:3;
• (d) roasting the mineral/Na2SO4 mixture under atmospheric pressure and in the presence of air at a temperature in the range of 700 to 900° C. for a period of 30 to 120 minutes;
• (e) cooling the mineral/Na2SO4 mixture to 25° C., and then mix with water in a water-to-calcined material ratio between 3:1 and 1:3;
• (f) leaving the calcined water/mineral mixture to rest for a period of between 30 and 100 minutes;
• (g) filtering the mixture of step 1 (f) to separate a leachate fraction and a solid fraction;
• (h) subjecting the first collected solid fraction to a second leaching with water in a water/solid fraction ratio ranging from 3:1 to 1:3;
• (i) obtaining a second liquid and solid fraction of the leaching;
• and
• (j) collecting the solutions of the first and second leaching, thereby obtaining a liquor rich in lithium in a content ranging from 100 to 7000 ppm.