Environmentally Safe Leaching?

I need some help from a Metallurgist to understand this.  Hondo Minerals is suggesting that they are going to use “a new patent pending process that creates a leaching type process without the use of hazardous chemicals such as cyanide” in their Tennessee Mine gold project.  More from their site:


Toxic chemicals previously used such as Hydrochloric and Nitric Acid are replaced with a water-based and pH adjusted medium to leach precious and base metals from mine tailings that is safe to humans and the environment.

Chemical and electrochemical processes are used to generate pH levels low enough to leach metals such as Gold, Silver, Zinc and Rare Earths into a solution for recovery at an extremely low cost per ton.

A major advantage to this proprietary leach process is the ability to selectively drop metals inherent to the ore, thereby reducing such processing complications such as zinc impregnation in silver.


Is this possible?  I mean, it would make some sense to me that it could be done with an acidic solution other than cyanide-based (again, I’m not a metallurgist so I don’t really know the details of cyanide leaching) but I’ve never heard of such a procedure and, as such, am a bit skeptical.  I’m leery particularly of it being “Environmentally Safe” when Uranium ISL gets so much flack for their method, typically utilizing water or hydrogen peroxide – not what one would consider hazardous chemicals.

Hondo Minerals should link or mention the patent application ID on the site – if it’s patent pending, the application is public domain as is the final patent, so it would be searchable.  I did find a few patent applications doing a quick Google search, so it seems it’s certainly being considered by those in the know.  Also, they may be patent-able and work in a lab, but would these applied patents be practical on an open-pit scale?