Q: What are the specific uses for EMEW® in the application of silver recovery from high grade ores?
A: EMEW® is appropriate for either partial or complete replacement of the Merrill Crowe process. Its specific uses include:

1. Direct recovery of silver and gold from the low tenor cyanide solutions (50-400 ppm Ag)
2. Retreatment and purification of Merrill Crowe precipitate (prevention of slag losses)
3. Retreatment and purification of ‘raw’ EMEW® silver powder
4. Direct recovery of dore from higher concentration cyanide solutions (+400 ppm Ag)

Q: What is the maximum solids (TSS) that can be put through the plant?
A: The EMEW technology is capable of tolerating a high concentration of solids without affecting the efficiency of the electrowinning process. When operating the cells in powder production there is a possibility of contamination of the product which is automatically harvested from the cell. It is therefore recommended that solids be maintained below approximately 500 ppm.

Q: What is the typical quality of the product?
A: The quality of product will be largely governed by the composition of your target solution and the levels of contained metals - such as lead, zinc and copper. The product from a highly contaminated solution will generally be in the region of 65% silver, with quality of >95% silver being possible from relatively clean solutions.

Q: What form is the product in, and what steps are needed to produce dore?
A: If your application requires single step recovery down to less than 1 ppm Ag, Electrometals will recommend installation of a plant designed to produce powder rather than cathode. The silver powder is periodically automatically harvested from the cells. If you have a requirement to produce a solid silver dore, the powder can be readily redissolved in cyanide and electrowon in a small EMEW cathode plant. The result is a high purity dore which can be sold directly to a refiner.

Q: What is the concentration of the barren solution?
A: The EMEW technology is capable of stripping metals to very low concentration. The silver tenor of the barren solution will be dependant on the design of a particular flow sheet. Electrometals can offer a plant which will operate in any concentration window, and which will strip silver to less than 1 ppm.

Q: Is de-aeration required?
A: One of the attractive features of the EMEW technology in this application is that many of the steps required in Merrill Crowe, such as de-aeration, are no longer required.

Q: Is the system capable of continuos operation?
A: The EMEW plant operates continuously, with metal harvesting being automatically controlled through a simple PLC.

Q: Are any filter aids required
A: No filter aids are required

Q: What improvements can EMEW® make to an existing brownfield Merrill Crowe plant?
A: The EMEW technology is perfectly suited to expanding silver production from an existing operation, even if Merrill Crowe is currently the primary installation at the site. Installation of EMEW facility does not add significant complexity to the project. Rather it has the capacity to take operating pressure off a Merrill Crowe facility and thereby both extend its life and increase its efficiency. The technology is capable also of completely replacing the smelting step in a Merrill Crowe plant – thereby achieving increase silver recovery (no slag losses) and, again, simplifying the total circuit.

Q: What is the typical operational cost ?
A: Between 0.08 to 0.15 US $ per ounce.

A typical comparison of operational costs is shown in the table below;