Patent ID: 8252086

Claim:
Procedure for extracting a value-metal, such as nickel, from a source material such as low grade ore or mine tailings; the procedure is characterised by including: providing a mass of the source material; a major part of the source material being sulphide minerals; providing a volume of liquid acid, and forming a slurry comprising the volume of acid and the mass of source material; containing the slurry in an activation-vessel; applying oxidative energy to the slurry, for a time period T 1 , in such manner as to procure oxidation of the minerals; applying the oxidation energy to the slurry at such a rate, and for such a time period T 1 , as to activate the sulphide minerals completely or nearly completely; whereby, during T 1 , the sulphide minerals dissolve in the liquid acid at a slow rate; then containing the activated slurry in an anoxic-vessel, under anoxic conditions, for a time period T 2 ; the time period T 2 is such that, during T 2 , the sulphide minerals dissolve at a high rate, which then starts to fall significantly; the relatively slow rate being slower than the high rate; whereby, during T 2 , the value-metal in the slurry undergoes a rapid dissolution phase; and then recovering the dissolved value-metal from the acid liquid.