Mountain Pass Pit
Processing begins with an understanding of the geology and REE mineralogy of the potential resource. There are certain key questions that need to be asked and answered:
1. GRADE. What is the grade of the potential resource? This is usually given in weight % (wt%) or parts per million (ppm) total REO or total REE. The grade can fluctuate across the deposit. Also, any potential byproducts and the non-economically valuable components in the host rock matrix should be known.
2. TONNAGE. What is the total tonnage of the resource or potential resource? How many tonnes per year REO can be produced? How many years of production are possible?
3. DISTRIBUTION. What is the concentration or relative distribution of each REE in the potential resource? Each REE host mineral and mineralized area has a somewhat unique distribution, and it can vary widely based upon mineralogy.
4. IMPURITIES. Are there any elemental impurities of concern associated with the REE minerals? Example impurities are Pb, U, Th, and F.
5. EXTRACTABLE REO. What portion of the REO is extractable using industry standard procedures? What is the elemental distribution of the extractable portion? It is often seen that the in-ground REO distribution and the first stage of mineral concentrates have a slightly different REO distribution. The LREEs are usually extracted at higher percentages. One should know the extractable REO values for each stage of production, as well as the total extracted REO values which show up in final products.
6. GEOLOGICAL MINERALOGY. Sufficient mineralogy studies are needed to characterize the entire potential resource, and provide confidence about the recoverability of REO across the resource using standard industrial procedures. There are aspects of mineralogy which a geologist needs to know to help locate additional nearby deposits, as well as gain confidence/understanding to be able to predict what type of material can be expected to exist between drill holes. With this understanding, analogies can be made to other, more thoroughly understood geological systems.
Mount Weld pit