die Lehrstunde ging weiter
Issue 1 - Production costs p/lb:
As the Captain has already mentioned, your knowledge on Anomaly A is not up to date. The scoping study was in fact ongoing, & further testing has reduced the projected costs to $22.79 p/lb in January 08.
But now it starts to get interesting! This cost reduction was based on reducing acid usage from 30kg/t down to 26kg/t. HOWEVER, they mention in the Oct 08 Quartely: "However, IMO noted that RC chips tested [In the scoping study] were of a fineness that has likely led to an over-estimation of acid consumption per tonne of material processed. Subsequent test work has shown that a substantial reduction in expected acid consumption to less than 20 kg/t is highly probable. This would losely approximate acid consumption levels published for Rössing Mine. . Then they add: "To date initial results from leach optimisation testing have been received. These interim results have confirmed the amenability to acid leaching and ... also indicate the potential for a substantial reduction in acid consumption compared to previously tested RC chip samples." .... So in other words they are saying: 'We are achieving 20kg/t, so $22.79 is a conservative figure, further reductions are expected!'
Bearing in mind that sulfuric acid is one of the biggest production costs they add: "The Company notes that spot sulphur prices have declined significantly in recent times from historic high levels and are now below those used in the Scoping Study. Spot prices are now quoted at below US$100/t."
Issue 2 - Heap Leaching
Now I have to admit that it is here that I need to take a breath & remain calm!!! You say: "BMN is doing more costly Heap leach trials, that means some ore can't use conventional acid leach process , that will further increase op cost."
"That means some ore can't use conventional acid leach process." ..... Do you honestly know what you are talking about? What exactly is the "conventional" acid leach process? (Take a deep breath Tibbs......)
OK, lets do some basic explanation. There are actually two "conventional" acid leach methods. Bannerman have done their scoping study based on using TANK LEACHING. This is self explanatory. The ore is placed in constructed TANKS, the leaching solution is placed into the tank, and the process begins. Generally it is a continous circuit of tanks, the pregnant solution flowing from one tank to another until completion. The tanks are complex, involving internal propeller mixers, pumps, electronics etc.
Here is a website discussing Tank Leaching: http://wiki.biomine.skelleftea.se/wiki/index.php/Tank_leachi…
Now we come to conventional Heap leaching. Basically, the ore is placed in prepared pads, normally open dugout ponds covered in rubber matting. The solution is sprinkled over the top & then permeates through the "heap" collecting the u3o8 as it soaks through. When it hits the bottom, the pregnant solution drains out & is taken away for separation.
Some info: http://wiki.biomine.skelleftea.se/wiki/index.php/Heap_leachi…
The two processes basically achieve the same result. The difference? Tank Leaching is significantly more expensive, especially in a low grade, bulk tonnage project. You have to build a massive tank reactor assembly. Heap leaching is dirt cheap! Bulldoze the valleys, cover them with matting, drain off to a collection point, & thats it. Tank leaching is faster, but the tank volumes are much smaller. Heap leaching is much slower, but you can make as many as your land area will allow. The end production result will be the same
With this in mind, BMN have announced the following: "The preliminary results of the DFS work have been highly encouraging. The Anomaly A ore is relatively soft and leaches relatively freely at very coarse grind sizes and at ambient pressures and temperatures. The result of this work has highlighted the very real potential for the ore to be treated via heap leaching as an alternative to conventional tank leaching. The significant advantage of processing via heap leach is a substantial reduction in overall capital which should translate to a material improvement in project economics and a broadening of financing options. This is of considerable strategic advantage in the current challenging credit environment.."