| 摘要 |
Gold and silver are usually obtained by stirred leaching of the ore, after it has been ground, with an aqueous alkaline cyanide solution containing oxygen. The problems which can arise during the leaching include long leaching times, the maintenance of a sufficient amount of dissolved oxygen and a high consumption of cyanide, which can give rise to slow or incomplete extraction of the precious metal. The addition of small amounts of inorganic sparingly soluble peroxides and in particular of calcium peroxide, for example at the rate of 0.1 to 20 parts by weight per 1000 parts by weight of ore, provides an efficient means of regulating and maintaining appropriate dissolved oxygen levels and can provide one or more advantages in respect of increasing or accelerating the extraction of the previous metal and reducing the consumption of cyanide. The insoluble divalent metal peroxides can be produced at a rate regulated by the leaching process by virtue of monitoring the dissolved oxygen levels and pH in the leaching process and using the monitored levels to regulate the rate of addition of hydrogen peroxide to the divalent metal compound as well as the molar ratio of the two reagents. <IMAGE>
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