1992-05-04_REVISION - M1988112 (3)

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CAPITAL COSTS Capital costs for the Inco SO~lAir process depend on the type of treatment required and the size of the operation. The main capital items ain a reaction tank, a mixer with motor and support, an air compressor (or blower) with associated pipings an SO2 reagent system with associated instrumentation an¢ piping, a copper sulfate delivery system (when required) and 8 lime delivery system. For a large installation (3300 stpd) requiring 5 to 10 stpd o€ SOZ and treating pulps for total cyanide detoxification, the principle equipment cost is about C $ 500,000, or about C $ 1.2 million installed. Alternatively, the same operation only inquiring seasonal pond water treatment can have a cost of C $ 500,000 installed. In many cases existing equipment can be used for operations switching to the Inco process. For temporary installations such as required for heap rinsing, the capital cost can be minimized by converting the existing barren solution pond into the SOalAit reactor. The SOZ delivery system can be leased and only requites the installation of a delivery line. Air blowers can also be leased and existing lime (or caustic) systems can be used for pH control. OPERATING COST'S Operating costs including reagents, labour, electric power, maintenance and licensing fees vary between 9 cents to C $ 1.58 per st of ore. The lower operating costs are for treatment of pond water where the advantage of natural degradation can be taken. A typical operating cost for a plant treating CIP tailings using liquid SO, is C $ 1.18 per st. One of the main advantages of the Inco SO~/Air process is the low cost of SO„ which is available in many forms. The least expensive is roaster gas (when available) and, in increasing order of cost, elemental sulfur burning, liquid SO2, and sodium sulfite or sodium metabisulfite. Hope Brook implemented the Inco SOZ/Air process in late 1990 converting from a previous 6