"Iron cap" an oxide ore containing gold 9g / t to limonite mainly by the grinding tends to form a thin sludge, it is difficult to process the ore. In oxidized ore, the particle size of gold is generally 0.001 to 0.005 mm, which occurs in the crack of limonite, and the individual larger gold particles are only 0.074 to 0.06 mm. Since the fine gold particles after grinding have entered the slime, they have been treated by amalgamation -shaker, amalgamation-flotation, amalgamation-flotation-diafiltration cyanidation, and the recovery rate of gold is only 63. %about. After the electrochlorination-resin slurry test, the recovery rate of gold was increased to 83.80%.
1. Electrochlorination leaching and resin adsorption of gold
The electro-oxidation-resin slurry method is to crush the ore and grind it, and then add it to the electrolytic tank together with sodium chloride, hydrochloric acid and resin, and electrolyze leaching and resin adsorption to produce gold-loaded resin and cathode mud. Finally leaching slag and tailings. The test used a 717 type styrene strong basic anion exchange resin.
Electrochlorination is carried out by electrolyzing an alkali metal chloride (usually sodium chloride) to release active chlorine in an aqueous solution to oxidize gold in the ore to AuCl 3 , thereby becoming HAuCl 4 and its double salt NaAuCl 4 , and in water. Dissociation into ions:
HAuCl 4 
H + +AuCl 4
NaAuCl 4 Na + +AuCl 4
AuCl 4 Au 3 + +4Cl -
The resulting AuCl 4 - is adsorbed by the anion exchange resin. During the process, Au 3 + generated by dissociation is deposited on the cathode plate to form a cathode mud.
Hydrochloric acid is added to the electrolytic cell, in addition to being able to precipitate a part of chlorine during the electrolysis process, and is mainly used to prevent chlorine generated by dissociation of sodium chloride from being absorbed by alkali or water to deplete active chlorine.
In view of the fact that the cathode diaphragm is easily blocked by fine-grained slime, this method uses a diaphragm-free stirred electrolytic cell. The electrolytic cell is a cylindrical steel plate groove, and the tank serves as a cathode (φ900 mm × 1000 mm). The stirring paddle is φ300mm and the rotation speed is 374r∕min. The anode is made of a 250×700 mm graphite plate, 5 pieces per groove, and is fixed between the stirring paddle and the groove wall along the circumference of the electrolytic cell with a pole spacing of 200 mm. The working conditions are: ore particle size 71.92%-0.074mm (200 mesh), pulp concentration 22.25%, area current 285A∕m 2 (current concentration 0.65A∕L), tank voltage 13V, liquid temperature 50°C. The slurry prepared by mixing 30 kg of sodium chloride and 20 kg/t of hydrochloric acid according to the raw material has a pH of 2. Then add 10kg ∕t of 717 type wet resin of -16～+50 mesh, chlorination and adsorption for 8h under continuous stirring. After 144h test, the average index obtained is: resin gold content 1.69mg∕g, tail liquid containing gold 0.03mg∕L, removing a small amount of cathode mud on the cathode (including 6.26g∕t), negligible, gold adsorption recovery rate It is 99.10%.
In order to investigate the effect of gold-bearing sulfide ore (mainly pyrite) on electrochlorination, a mixed ore sample test containing 30% sulfide ore was also carried out. The results show. The addition of a small amount of gold-bearing sulfide ore has little effect on the leaching and adsorption of gold.
A good separation effect was obtained by separating the gold-loaded resin from the slurry by a jigging-shaker combined process.
Second, the elution of the resin
The elution of gold on the resin was carried out by electrolytic elution precipitation. The test used a φ340mm×500mm porcelain mixing drum. A φ70mm propeller is installed in the barrel at a speed of 252r∕min. The elution slag contains 4% thiourea, 2% hydrochloric acid, and a solid-liquid ratio of 1:7. Graphite anode plate, a cathode lead plate, the pole pitch of 80mm. The current density is 400 A ∕ m 2 and the cell voltage is 2V. After 8 h of electrolysis, the elution rate of gold on the resin was 99.6%, the precipitation rate of gold was 98.2%, and the loss rate of thiourea was 16%.
The electrochlorination and electroelution operations were carried out in a sealed electrolytic cell, and the extracted exhaust gas was purged with a 2% NaOH solution in a gas scrubbing tower and discharged into the atmosphere. Because the particle size of gold in the ore is small, the grinding particle size does not meet the requirements, the gold content of the leaching slag of the sample does not fall below 1g/t, and the total recovery rate of gold is only 83.80%. However, the recovery rate has increased by 20% compared with other methods.
Third, the regeneration of resin
The gold-eluting resin was firstly stirred with 2% sodium hydroxide solution (solid-liquid ratio 1:3) for 2 hours, filtered and rinsed with water to neutrality. The mixture was further stirred with 2% hydrochloric acid (solid-liquid ratio 1:3) for 2 hours, and the resin was returned for use.
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