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KCA Carbon Converter

The Carbon Converter is a modular, self-contained unit for converting carbon fines into a fine dry ash. Dirty wet carbon fines are loaded directly into the roasting chamber and the resulting ash is fully captured as a dry product. A three-stage exhaust scrubbing system fully captures mercury to satisfy the emission standards of every US state and foreign country. Gold and silver recovery up to 99% has been demonstrated in operation. 

Process Description
The Carbon Converter is designed to process 300kg of clean dry carbon per day. The actual throughput is based on the carbon composition and moisture content of the feed material.

Two interchangeable bottom sections of the furnace allow for semi-continuous operation. The semi-continuous batch system is easily operated by one person through a sophisticated PLC interface.

The process begins as carbon fines are loaded into the feed hopper. An automated conveyor then transfers the fines material to the top of the furnace. The carbon is continuously and evenly distributed over a thick bed of silica sand by a rotating distributor head. A burner is used to preheat the furnace. Hot air is pulled down through the carbon which combusts to provide operational heat. Excess water is evaporated, and the carbon begins to ash.

Carbon is continuously burned in the furnace until the level of accumulated ash alerts the operator to exchange bottom sections for the next ashing cycle. The carbon ash is then easily collected and removed for gold and silver recovery.

While the carbon is burning, hot exhaust gas flows through a series of two venturi wet scrubbers, using water at ambient temperature to remove the bulk of volatiles, including most of the mercury. Mercury is collected in a conical sump below each scrubber. Water for this stage is a process solution, flowing into the system and discharging back into the leaching process. As a final polishing step, the cooled exhaust gas passes through a tank filled with sulfur-impregnated carbon to remove any trace amounts of mercury from the exhaust gas stream. Once the ashing cycle is complete, the ash, which has been roasted at high temperatures, contains no mercury.