Process Research Ortech Inc.

M A Halim

Ramamritham Sridhar

Vaikuntam Iyer Lakshmanan

Jonathan Chen

Robert J DeLaat

A process for the extraction of gold from a gold-bearing ore or concentrate, comprising the steps of leaching the gold-bearing ore or concentrate with a lixiviant of hydrochloric acid and magnesium chloride at atmospheric pressure at a temperature of at least 90&#xb0; C. and an Eh of at least 900 mV. After a liquid/solids separation step, the solution obtained is subjected to an organic solvent extraction step using an oxime to obtain a solution of organic solvent containing gold, which is stripped with sodium thiosulphate to recover gold. The extraction may be operated to extract gold with or without iron. Materials used in the process may be recycled. The process avoids environmental and other hazards associated with the use of cyanide to extract gold.

Chloride process for the leaching of gold

A process for the extraction of rare earth elements, including yttrium, from a rare earth element-bearing ore or concentrate, comprising the steps of leaching the rare earth element-bearing ore or concentrate with a lixiviant of hydrochloric acid and magnesium chloride at atmospheric pressure at a temperature of from 90&#xb0; C. to the boiling point of the solution and at an Eh of at least 200 mV. After a liquid/solids separation step, the solution obtained is subjected to steps for removal of iron and for recovery of rare earth elements. Alternatively, rare earth element-bearing ore or concentrate may be leached with sulphuric acid and liquid obtained subjected to extraction of iron and other impurities. Raffinate obtained may be treated with oxalic acid, the precipitate dissolved in hydrochloric acid and subjected to solvent extraction for rare earth elements or the raffinate may be subjected to solvent extraction for removal of rare earth elements and then stripped with hydrochloric acid.

Process for extraction of rare earth elements

The invention provides a process for the leaching of a laterite ore, concentrate, tailings or waste rock for the recovery of value metals, at least one value metal being nickel. The laterite ore or concentrate is subjected to a leaching step with a lixiviant comprising hydrochloric acid to leach nickel from the laterite ore, followed by a liquid/solids separation step. The liquid obtained is subject to solvent extraction with a dialkyl ketone, to obtain a solution rich in iron and a raffinate. Separation of iron from cobalt and nickel is obtained.

Growing community of inventors

Mississauga, Canada

M A Halim