Frequently Asked Questions
Q: How sensitive is the process to variability in the feed?
A: The process is semi-continuous batch, with the batch cycle time dependent on the feed material. We have seen cycle times as short as one (1) hour long and as twenty-four (24) hours. Feeds which are very high in clay may require agglomeration, which can be done by the operator in a modified drum concrete mixer. It is important to note that agglomerating the feed will increase cycle times.
Q: What test work is recommended for each site/carbon product?
A: Test work is recommended for each sites carbon product, the test work will require gathering representative samples of the waste carbon on site. Sample analyses and assaying for gold, silver, carbon, and moisture content along with some basic physical characterization (visual inspection and screening). Based on the results KCA will conduct a design/cost analysis and determine the payback period as well as determine design factors and optimal operating conditions for the equipment.
Q: What is the actual product I'm getting from the unit? How much product does it yield?
A: The product will be a mix of carbon ash containing the gold, a small amount of silica sand bed material from the hearth, and any non-combustible material that was fed with the carbon. The actual amount of ash product is highly dependent on how much non-combustible material is present in the feed.
Q: How do I treat the ash to get my gold?
A: There are two options for ash treatment.
Option 1: Direct Smelting
Option 2: Fine Grinding & Leaching
Q: How much floor space/footprint does the unit require?
A: The installed Carbon Converter footprint with the feed system is approximately 7.5m x 7.5m, this includes space required for proper operation and maintenance access.
An additional 6m x 8m carbon preparation space is also recommended to facilitate daily operations.
Q: How is mercury controlled/captured?
A: Hot exhaust gases from the furnace are cooled and treated with two wet venturi scrubbers in series, which drop mercury for periodic collection from their respective tanks. The exhaust exiting the second venturi then passes through a bed of sulfur impregnated carbon to capture any residual mercury.
In some cases, it is possible a minuscule amount of condensed mercury can be carried out with the cooling solution stream. If this is not acceptable, then filters can be installed on the solution outlet.
Q: What are the utilities requirements?
A: An electrical feed requirement capable of supporting a 40HP / 30KW electrical load.
A burner requirement of 400,000 BTU/hr (100,000 kcal/hr), which can be powered by either natural gas, propane, or diesel.
A cooling/scrubber solution requirement of 20gal/min (4.6 m3/h), which can be pregnant solution, barren solution, or raw water.
Q: What is the cost to run the unit?
A: Operating costs can range from $50,000 - $100,000 per year, excluding labor costs. These costs depend in large part on the nature of the feed. KCA provides a more concise operating cost estimate upon evaluation of each operation’s carbon.
Generally, with clean carbon and long furnace runs, we expect minimal operator time will be required. Dirty carbon may cause more difficult materials handling which may result in higher labor costs.
KCA will help define these costs more accurately as information is received regarding your carbon.
Q: I need to process more than the designed throughput. Do you have a larger unit?
A: Currently, there is one size unit, but multiple units can be provided to reach the desired throughput. The unit is of a modular design that can be easily setup, taken down, and packed into a 40ft shipping container. The size is convenient for a single person to operate one or multiple units.
Q: Does the unit have to be installed indoors?
A: The unit is designed to be installed indoors but can be installed outside with proper protection from the elements.
Q: How soon can the unit be delivered?
A: Upon receipt of purchase order and down payment, KCA can be ready to ship from our shop in Reno in approximately 16 weeks.
Q: What is your warranty/guarantee on the equipment?
A: KCA will guarantee the equipment for a period of 12 months after completion of commissioning. The equipment is warranted against component failure due to faulty equipment or construction. KCA will repair or replace components at KCA's cost and responsibility. KCA will include one follow-up visit at no charge after commissioning to assess the performance of the unit and perform repairs/adjustments if necessary.
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