| Summary and Recommendation | WNP Processing Plant Air Discharge Assessment | 4397169-66885702-113 | 16/06/2022 | 24 Sensitivity: General Ore Processing At the processing plant, gold and silver are extracted from the ore. Ore processing consists of the following stages: ● crushing and grinding of the ore ● addition of process water (generally decanted from the tailings pond) to form a slurry ● addition of lime to the ore, and cyanide solution to the slurry, to leach the gold and silver into solution ● addition of carbon to adsorb (attach) dissolved metals and remove them from the slurry ● stripping the metals from the carbon by acid washing and circulation of a caustic cyanide solution ● precipitation of the gold and silver by electro-winning ● smelting of metal products into bars of doré bullion ● pumping of the barren slurry (tailings) to the tailings storage facility. These stages can be described under three main headings: ● grinding and size classification to reduce the ore down to a fine particle size ● leaching and adsorption to extract the precious metals from the rock ● recovery of the precious metals to produce doré bullion bars. The Processing Plant process flow diagram is shown below. Grinding and sizing Ore processing is a 24-hour operation. Ore is stockpiled at the processing plant, and the process begins by feeding the ore into a hopper with a loader. The ore is conveyed, and lime is added to raise the pH of the
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