Patent FR-2966470-A1 (FR)
Title: Treating gold ore to extract gold contained in ore, by placing ore having liquid and solid phases and then forming prepared ore from ore, placing etching solution comprising sodium thiosulfate, and mixing prepared ore with etching solution
Inventor: QUEYROIX CHRISTIAN
IPC: C22B3/12
Filed: 2010-10-25
Abstract: The process comprises placing ore (12) having a liquid phase (12L) and a solid phase and then forming a prepared ore (14) from ore, placing an etching solution (16) comprising sodium thiosulfate, cupri-ethylene-diamine or sodium thiosulfate, copper sulfate and nickel sulfate and polyethylene amine, mixing the prepared ore with the etching solution in an etching container to form an ore pulp (18) so that, during an etching phase, that etching solution dissolves the gold contained in the prepared ore, and capturing solubilized gold during the etching phase by receiving unit. The process comprises placing ore (12) having a liquid phase (12L) and a solid phase and then forming a prepared ore (14) from ore, placing an etching solution (16) comprising sodium thiosulfate, cupri-ethylene-diamine or sodium thiosulfate, copper sulfate and nickel sulfate and polyethylene amine, mixing the prepared ore with the etching solution in an etching container to form an ore pulp (18) so that, during an etching phase, that etching solution dissolves the gold contained in the prepared ore, capturing solubilized gold during the etching phase by receiving unit and constituting a weak solution (28) devoid of gold, retaining a portion to be preserved of the weak solution and reusing the part to be preserved of the weak solution to form the etching solution, and purging a part to be exclude from the weak solution towards a neutralization unit to neutralize the adverse effects of the part to be excluded from the weak solution on the environment. The formation of the prepared ore comprises removing a part of the liquid phase of the ore so that the prepared ore has a liquid phase and a solid phase in predetermined proportions defining a flow of introduction of liquid phase of prepared ore to mix with the etching solution, and removing a portion of the liquid phase of the ore to obtain a rate of introduction of liquid phase of prepared ore in the ore pulp such that the liquid phase of prepared ore is 3-20% of the total weight of the prepared ore. The part to be excluded of the weak solution is purged at a purging rate equivalent to the rate of introduction of the liquid phase of prepared ore to be mixed with the etching solution. The receiving unit fixing the solubilized gold comprises active carbon and ion exchange resins or metal powders. A very low amount of cyanide is used to pass the solubilized gold in the aurothiosulfate form to aurocyanide form before the solubilized gold is captured by the activated carbon. The ore pulp is transformed, during the etching phase, into an etched pulp (20) having a solid phase and a liquid phase also called rich solution in which solubilized gold is present and in which the solubilized gold passes the aurothiosulfate form to the aurocyanide form. During a separation operation, the solid phase of the etched pulp is separated from rich solution to recover the rich solution and the solid phase of the etched pulp weak in gold is isolated to recover the liquid phase of the etched pulp low in gold corresponding to the weak solution. During a phase for transformation into aurocyanide, very small quantity of cyanide of 5-20 mg of cyanide per liter of rich solution is introduced into that rich solution so that the gold dissolved in the rich solution passes from the aurothiosulfate to the aurocyanide form. During a phase of recovery of gold, the activated carbon and the ion exchange resins or metal powders are used to capture the solubilized gold in the aurocyanide form. The prepared ore and the etching solution are mixed with the activated carbon, ion exchange resins and the very low amount of cyanide. The prepared ore is placed on an etching container forming a sealed area, and the etching solution sprays the prepared ore. During the attack phase, the etching solution etches the prepared ore by percolation to obtain a rich solution in which the solubilized gold is present. The prepared ore is placed on an etching container forming a sealed area and the etching solution prepared this mineral waters. The step of removing a portion of the liquid phase of the ore is operated by a module consisting of a drying tube, spin-dryer, centrifuge, pressure belt filter, filter press, horizontal belt filter or forced or natural evaporation module. The part to be preserved of the weak solution is discharged into a storage container of the etching solution. The storage container of the etching solution is connected to a preparation container of a concentrated etching solution. The etching container is connected to the preparation container and is fed in concentrated etching solution. The process further comprises carrying out an electrolysis of the part to excluded of the weak solution so as to recover the copper contained in that part to be excluded of the weak solution and then meeting the standards of copper material discharge in environment. The part to be excluded of the weak solution is neutralized by neutralization agents to recover copper and limit the effects of the part to be excluded of the weak solution on the environment and by total or partial evaporation of its liquid phase then recovery of copper and neutralization of the residual part. An independent claim is included for a system for extraction of gold contained in the ore by the treatment of the gold ore.