RE: About Percentages & Recovery Dear Canadian Ungulate (do permit me some jest!)
It is my understanding that % iron recovery is a (somewhat secondary) consideration in calculating the number of tonnes of concentrate that will be recovered from a given tonnage of ore.
Primary testwork on low to mid-grade iron ores investigates the % weight recovery. The % iron recovery simply is what it is and is determined through instrumental analysis after the physical separation tests have been optimised – the higher the % Fe recovery the better of course but it can be looked at as a secondary consideration (it isn’t really of course, but lower Fe recovery means that the physical separation of iron bearing minerals from gangue would have to be more effective to reach desired final concentrate Fe grade).
The important thing is that enough of the iron can be recovered to make a concentrate that meets industry specifications. Most concentrating operations will produce a concentrate at 65 % or greater Fe - a level that generally satisfies industry as long as deleterious metals (P, S, Al, Mn, Si, etc) are at a low enough level.
If the weight recovery is stated at 37 % then out of each tonne of ore will come 0.37 tonnes of concentrate. (Fe recovery unknown until determined)
A more common way of expressing this is that it will take 1 / 0.37 or 2.7 tonnes of ore to make 1 tonne of concentrate.
If the weight recovery is stated at 40 % then out of each tonne of ore will come 0.40 tonnes of concentrate. (Fe recovery unknown until determined)
A more common way of expressing this is that it will take 1 / 0.40 or 2.5 tonnes of ore to make 1 tonne of concentrate.
BG