Effect of temperature on the dissolution rate of gold
If the temperature is within the allowable variation of the gold dissolution operation, the reactant concentration will increase with increasing temperature and diffusivity, and the reactant concentration will increase by about 20% for every 10 °C increase in temperature. That is to say, increasing the temperature accelerates the chemical reaction rate. That is, for every 10 °C increase in temperature, the decomposition rate increases nearly twice. But the trouble is that increasing the temperature will affect the solubility of oxygen. When the pulp temperature approaches 100 ° C, the solubility of oxygen has dropped to near zero. In general, the highest dissolution rate of gold reaches its limit at a temperature of about 85 ° C (Fig. 1). If the temperature is increased again, the dissolution rate of gold is lowered by the decrease in solubility of oxygen. In order to increase the temperature of the slurry, a large amount of fuel is consumed, which increases the cost of the cyanide operation. In particular, as the temperature of the slurry increases, the rate of cyanide dissolving the base metal increases, and the hydrolysis of the alkali metal cyanide and the metal cyanide on the alkali is accelerated, resulting in an increase in the consumption of cyanide. These adverse effects are not compensated by increasing the temperature of the slurry to increase the dissolution rate of gold and shorten the cyanide time. Therefore, in addition to heating in the cold region in the winter in order to prevent the slurry from freezing, the cyanidation is generally carried out under normal temperature conditions of not less than 15 to 20 °C. Fig.1 Effect of temperature on the dissolution rate of gold in 0.25% KCN solution In the typical diffusion control process, the decomposition activation energy of gold and silver ranges from 8.37 to 20.93 kJ (2 to 5 kcal) / mol (molecular). Aerosol Cone and Dome Production Lines Spray Can Making Machine,Aerosol Can Making Machine,Aerosol Tin Can Production Line,Aerosol Bottom Dome Making Machine Zhoushan Golden Wing Machinery Co., Ltd. , https://www.goldenwingmachine.com