VCIC (Vertical) vs CIC (Traditional/Cascading)
Clint Green, Forte Dynamics, CO, USA
Capital cost is the biggest differentiator in comparison of the two and in almost every circumstance the VCIC has the advantage. This is due to the reduced footprint and the height of structure and therefore building, if one is required. The barren flow coming from the most elevated tank allows flexibility on the height of the barren tank, which in turn opens up the opportunity to optimize Barren Pump selections. In CIC design, the raising of the barren tank has a knock on effect of raising everything upstream, thereby increasing the capital cost. This includes structural steel for the support of cascading CIC tanks. The VCIC design is self-supported by a concrete foundation, like other conventional tanks.
VCICs are typically fabricated in full (exception of site glass and minor items) and shipped to site. The full VCIC train can be set in place with a crane in fairly short order. This is a significant time savings compared to setting the steel support prior to placing each column. It also eliminates the time spent welding the external launder that often accompanies large cascading columns.
Operating costs are very similar. There is an advantage to the VCIC operational cost due to the smaller footprint and heating of the area. This is a larger consideration in cold climate heap leach operations. Included in the operational cost is maintenance, which is similar and requires very little maintenance that requires shutdown or bypassing of the tanks. In the case of the VCIC, the whole train would need to be bypassed if work is required on one tank. While this is a concern, it is one that we discuss in detail with our clients and include in our design to mitigate this risk. The risk is mitigated to a point that operations that have VCIC and CIC on sites do not differentiate between the process when looking at availability, as down time of either is negligible on an annual basis.
The process design is the same for both designs for carbon bed fluidization and adsorption efficiency and therefore recoveries are expected and have shown to be the same. However, projects may choose a 5-stage CIC to reduce capital costs (footprint, building height, structural steel, etc.), while for a much lower cost, a 6-stage VCIC can be implemented and yield higher efficiency by comparison.
Forte Dynamics is a mining and heap leaching consulting firm that brings diverse expertise and decades of experience to your project. We are professional engineers — with special expertise in mining, processing, metallurgy and hydrodynamics — who bring appropriate levels of analysis and pragmatism to every problem. Working as part of your team, we help you analyze the crucial trade offs — technical, financial, regulatory and environmental — that lead to innovative solutions, optimal decisions and improved mining project performance. Find out more at www.fortedynamics.com.