Non-toxic sodium cyanide carbon slurry method

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A slurry adsorption process for extracting dissolved components from leached pulp by activated carbon in a carbon-in-pulpprocess chemical beneficiation leachate treatment operation. It is mainly used to extract gold and silver from cyanide pulp. Gold or silver may also be extracted from the leaching slurry obtained from other gold-soluble chemicals, such as gold or silver extracted from the sulfur leaching slurry. A brief history of 1847, Russia, Razovsky (M.la plus Bc. [i] found that activated carbon can adsorb precious metals from solution. In 1934, people could use activated carbon to adsorb gold from the slurry, but it was not until 1952 that Jadea (JBZa hit a) used a mixture of hot sodium hydroxide and sodium cyanide to desorb gold from gold-loaded charcoal. The foundation of the contemporary carbon slurry method. In 1961, the Carlton concentrator in Colorado, USA, used the carbon slurry process for small-scale production for the first time. In 1973, the Homestead concentrator in South Dakota, USA, used the perfect carbon slurry process for the first day of 2250t. Gold factory. Since then, South Africa, Australia, Zimbabwe and other countries have successively established dozens of carbon slurry gold extraction plants.

China began to study the carbon slurry process in the late 1970s. In 1985, a carbon slurry gold extraction plant was established in Linghu Mine and Chiweigou Mine. Since then, more than a dozen carbon slurry gold selection plants have been built. CIP process technology for gold extraction process principles include raw material preparation, stirring and leaching, carbon countercurrent adsorption, desorption loaded carbon, electrodeposition pregnant solution (pregnant solution or the zinc powder-deoxy-substitution), and carbon regeneration ingot smelting operations. The mined and graded pulp is pre-screened to remove grit and wood chips, and then concentrated to a solid content of 40% to 50% for liquefaction leaching and cyanide slurry feed to the carbon countercurrent adsorption system. The adsorption system generally consists of 4 to 6 adsorption tanks, and the slurry and activated carbon are countercurrently flowed through the inter-tank screen. The screen between the tanks may be a fixed screen (peripheral screen, bridge screen or immersion screen) or a vibrating screen. The carbon slurry process mainly adopts a fixed sieve. The carbon slurry is periodically raised to the upper tank by an air lifter, and the recycled carbon or new carbon is added to the final adsorption tank. The gold-loaded charcoal is periodically transferred from the first adsorption tank to the desorption system for gold desorption. And the regeneration of charcoal.

In the adsorption system, activated carbon and slurry flow in a countercurrent flow. After the adsorption, the tail slurry is inspected and sieved (the mesh hole is 24 mesh) to recover the lost fine-grained gold-loaded charcoal, and then sent to the tail slurry treatment process. The principle process of carbon recovery by carbon slurry method can be used to desorb gold and silver after removing wood chips and deliming.

(l) Zadefa. Desorbed with l% NaOH + 0.1% NaCN solution at 80-93 ° C and atmospheric pressure for 24 to 48 h.

(2) Alcohol law. Desorbed with soyC and normal pressure for 10 h with 10%-20% alcohol, 1% NaOH+0.1% NaCN solution.

(3) High pressure method. Desorbed with 1% NaOH + 0.1% NaCN solution for 2-6 h at 160 ° C and 0.35 MPa (5.5 atmospheres).

(4) South African Anglo-American company law. It is treated with a hot solution (930C) of an equal volume of 10% NaOH (or 5% NaCN + 2% NaOH) loaded with gold charcoal for 2 to 6 hours, and then washed with 5 to 7 times of deionized hot water in a volume of gold-loaded carbon. One 20h.

Desorb the resulting noble liquid delivery product. Stainless steel plate anodes and steel wool cathodes are generally used for the accumulation of noble liquid. The anode plate is drilled with holes to allow the electrolyte to pass uniformly. The cathode is made of steel wool in a detachable plastic frame with holes on both sides. The density of the steel wool is 359/L, so that the electrolyte can pass evenly and Prevent short circuits. Gold magic hair iron contained in the electrowinning output ratio of about 20: 1, iron in hydrochloric acid, after filtration and washing powder feed ingot smelting. The deactivated activated carbon is sent to a regeneration operation after pickling, alkali neutralization and water washing. Most plants are quenched after heating to 650 oc in an indirect heating rotary kiln to restore the activated carbon to adsorption activity. After the regenerated activated carbon is sieved to remove the fine-grained carbon, water is added to form a carbon slurry returning adsorption system for recycling. May also be a shaft furnace or a furnace carbon regeneration chamber, it can be used oil, coal, gas or electric heating. The gold-loaded charcoal can also be desorbed by pickling, and the gold-loaded charcoal can be washed with 5% hydrochloric acid or nitric acid to wash away the calcium carbonate passivation film on the surface of the carbon, as well as calcium, silicon, zinc, nickel , iron and flotation reagents. Organic impurities, warming can strengthen the washing process. The acid-loaded charcoal after pickling is washed to neutrality, and the chloride or nitrate is removed and then sent for desorption. Desorption after pickling can exclude the above pollutants from the desorption and electrowinning system in time, which can enhance the surface activity of activated carbon and increase the adsorption rate of gold.

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