Method of recovering metal values from nickel-containing ores

A method of recovering metal values from ores containing iron, nickel, cobalt, magnesium, and aluminum, comprising:

• a) leaching the ore with HNO3 for a sufficient time to form a slurry;
• b) separating any undissolved residue to form a solution:
• c) precipitating the iron from the solution as Fe2O3.3H2O;
• d) precipitating aluminum as Al2O3, and leaving a solution containing nickel and cobalt values;
• e) performing thermal hydrolysis, or pH balance (shift), or sulfide precipitation, or solvent extraction to form Ni(OH)2 and Co(OH)2, or NiS and CoS, or Ni/Co salts in solid form, and removing the nickel-cobalt values as a precipitate;
• f) recovering HNO3 and NOx from the process;
• and
• g) reforming the removed NOx containing gases into nitric acid for further use.

A method of recovering metal values from sulfide ores containing iron, nickel, cobalt, magnesium, and aluminum, comprising:

• a) leaching the ore with HNO3 for a sufficient time to form a slurry;
• b) separating any undissolved residue from the slurry to form a solution:
• c) precipitating the iron from the solution as Fe2O3.3H2O;
• d) precipitating aluminum as Al2O3, and leaving a solution containing nickel and cobalt values;
• e) performing thermal hydrolysis, or pH balance (shift), or sulfide precipitation, or solvent extraction to form Ni(OH)2 and Co(OH)2, or NiS and CoS, or Ni/Co salts in solid form, and removing the nickel-cobalt values as a precipitate;
• f) recovering HNO3 and NOx from the process;
• and
• g) reforming the removed NOx containing gases into nitric acid for further use.