Further to Our Report on the Metal Recovery Test Work
Hello again. I have received a lot of comments from the recent press release. Most of them are “huh” or “was that English?” So I'm going to go ahead and try to translate a very technical PR into something more readable.
As you know, we are after 3 different metals: tin, copper and silver.
Let’s talk about the copper first.
Over the years some of the copper has been oxidized on its own volition. In other words it was originally hosted in a sulphide mineralization but nature (wind, rain, freezing, heat etc) has released some of it on its own. This means you have some of the copper ready for the picking and the remainder is still locked upon in a sulphide which needs additional help for recovery. So the first step is to use a weak acid wash to liquify the easy copper into solution (copper dissolves when it touches acid). This produces a “pregnant” solution and then regular iron is used to separate the copper from the solution. The copper literally is Substituted for iron and precipitates s copper metal. The end product is called copper cement and usually runs minimum 98% pure. A good product for sale. After this step the tailings move to what is called flotation. Flotation involves the separation of the sulphide minerals, which contain the silver and balance of the copper, into what is called a concentrate. In other words you get rid of as much material as possible that has no value and capture the material that has the goods. We caputre 84% of the silver and about 80% of the copper into a concnetrate in this process. The "waste" from this process contains the majority of the tin which is not associated with sulphides and therefore does not end up in the concentrate. The "waste" therefore goes to another process in which gravity is used to recover the tin as tin is a heavy element and can be separated from the rest of the "waste".
The weak acid step at the beginning does not have any effect on the silver so its value is captured in the flotation stage. So how do we get the rest of the copper and as much silver as possible? Using what is called a brine leach we put bunch of salt in solution in tanks and heat it to 70 Celsius. This breaks down the sulphides and we extract a minimum of 80% silver and 80% of the copper from the flotation concentrate . Again we add iron filings to the solution and the silver and the copper form individual metals as they substitute for the iron metal (the iron goes into the solution). The final copper silver precipitate contains minimum 5% silver and 75% copper which we can either sell directly to get value for both the silver and copper or add a further step to produce individual silver dore bar that we ship to a refinery for purification and copper metal for sale..
What about the tin?
The tin in the tailings is very fine grained. This means it doesn’t react to flotation very well. It's too bad as 50% of the contained metal value, using today’s prices, is the tin. The university in Oruro (Bolivia) and Met-Solve in Vancouver were only able to get 25% of the tin into a low grade concentrate of 6%. This has to be better and we will continue to tweak the process to improve the grade. In this case we will be investigating the use of centrifuges that spin at a high rate and hopefully push the tin to the extremes for recovery.
All is not lost though. When we first looked at Telamayu it was strictly the silver and copper that we based our projections on. Its still a go even with a lower tin contribution. You have to remember that these tailings are very unique given the grades of the 3 metals are in a lot of cases better than what people are mining in open pit or underground mines. There is a lot of value in the tails and the metal is there for a reason. It was difficult to capture the metal years ago using inferior technology. Using modern approaches we hope to capture up to 50% of the value in the tails. (I’m not allowed to state the value in tails-IIROC rules).
Finally we are also looking at processing a whole-ore using a brine leach with no flotation. This would mean capturing another 20% of the silver but it comes at a cost of bigger and more expensive equipment. The Chinese engineering company, CASC, will to an analysis of whether it's better to go with route 1 or 2.
Given the current meltdown in the resource sector (IT REALLY IS BRUTAL) we need to find different ways to raise money than selling stock at 2.5 cents. Enter the metal traders. We are investigating entering into what is called an offtake agreement whereby we would commit to sell some of the copper or silver to a metal trader in exchange for dollars today. Their motivation is they will buy it at a discount to the world price and I say good on ‘em.
I’ve reached to a number of them and all I can say is “game on”