Mackowski Success Factors for Rare Earths Development – Part 2
In this article, I will continue the discussion on what I consider to be the KEY success factor for the development of a rare earth project; mineralogy. As previously introduced in Part 1, I see mineralogy as being the key due to its huge influence on the flow sheet and the resultant capital cost (CAPEX) and operating costs (OPEX) of the processing plant. It is the current difficulty of obtaining the funding of that CAPEX which forces me to make low CAPEX very important, and mineralogy is the key to having a lowered CAPEX.
In response to my first use of the term, success factors, I have been asked by a number of readers to explain where these factors come from. What I have done is to expand the Kepner-Tregoe (KT) Decision Making analysis tool. This is one of a suite of excellent thinking tools. Well worth researching if you want to improve your thought processes. The Decision Analysis tool quantifies the way we make decisions and uses the requirements of NEEDS and WANTS. These needs and wants are those attributes of the choices that are available when we make a decision. Think of employing an engineer to lead the development of a REO project. MUST be qualified. MUST have experience. WANT exposure to your mineralogy. WANT the remuneration package to be reasonable. You will have a number of applicants; those that do not meet the MUST requirements are quickly rejected. You then rank and score the remaining applicants according to the WANT requirements. What I have done is move on from relatively simple MUST and WANT requirements in the KT Tool and expand and re-define the requirements as success factors. This range of success factors can then be investigated when looking at the development of a rare earth project.
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In the previous article, I explained the simple impact that mineralogy has upon CAPEX. That is, the better the mineralogy allows a high grade beneficiation product to be produced; the smaller the downstream processing plant will be. This reduces CAPEX for comparable REO output capacity. But there is more to it. Those minerals that can easily be beneficiated into high grade mineral concentrates are monazite, bastnasite, xenotime and recently eudialyte. Now I am not saying that other projects with differing mineral bearing REO values cannot be successful. It is just that they will be more difficult to beneficiate, probably have a lower grade into the chemical plant, and probably have a higher CAPEX for the same REO output. Also note that the issue of by-product REO clouds the mineralogy success factor as key. Again, remember there are a number of success factors to be analysed and balanced.
However, oils ain’t oils, as they say. Just because you have monazite, bastnasite, xenotime or eudialyte does not mean you are in the home strait. When an ore is beneficiated, it is impossible to have as a product, 100% of your target mineral. Other minerals (non-valuable) may have similar properties and come along for the ride. The REO mineral itself is not pure. So you will have impurities. Obviously this reduces the REO grade of the mineral concentrate but the impurities also have an impact on the downstream flow sheet and the resultant CAPEX and OPEX. This impact can sometimes be quite severe. As an example, the Baotou REO mineral is bastnasite. The grade of the mineral concentrate entering the chemical processing plant is approximately 50% total rare earth oxide (TREO). However, the recovery of TREO from the ore after beneficiation is less than 25%. Why is the recovery so low? Most REO projects are reporting beneficiation recoveries of >80%! The reason is the mineralogy. If a higher recovery of TREO is attempted, the process also pulls significant iron bearing minerals. In fact so much iron that the impact on the downstream processing plant does not warrant the additional CAPEX and OPEX to “manage” that excess iron. The Baotou people have been investigating how to improve the TREO recovery whilst keeping the impurities down for many years, obviously without success. It was recently implied in comments to an InvestorIntel article that “Baotou tailings are a store of REO and could easily flood the market with REO”. There is a very difficult mineralogy problem to overcome first.
The reason I use the Baotou example is to demonstrate that although mineralogy is the key to producing a high grade beneficiated feed material for downstream processing, the contained impurities are also very important. The issue with the impurities is how much reagent will they consume? Iron containing minerals dissolve in the sulphation process using additional sulphuric acid, this adds to the OPEX. So do phosphate, manganese and aluminium containing minerals. All consuming acid. And there’s more. Since they are now in solution with the REO they now need to be managed such that they do not end up with the REO product as a contaminant. This management requires additional (or expanded) flow sheet with an impact on CAPEX, and processing efforts with an impact on OPEX. In one of my previous articles, I discussed radiation. Expect the thorium and uranium to follow the REO mineral into the beneficiation product. It will then need to be managed in the chemical plant. Others have stated that the separation process is the most difficult part of process development. I disagree. Beneficiation and the resultant chemical plant flow sheet before separation can be much more difficult.
So. Do monazite, bastnasite, xenotime and eudialyte all have the same ranking when looking at success factors? You guessed it. They are different, even if they produce the same grade of mineral concentrate. How different depends on quantifying the chemical processes required to dissolve the REO, to discard the impurities, and to produce a rare earth product of acceptable grade. It is possible to rank these four minerals in terms of ease of processing of the beneficiated mineral concentrate but to do so would over-simplify and would not give a proper consideration of other factors that must be brought in. So I will not mislead. I will not rank these four minerals. There are too many other success factors to consider. Grade is obviously important in the costs and results of beneficiation and the four minerals occur quite differently. Also note that just because you have mineral “A” does not mean you can be assured of success. For example, Baotou bastnasite and other well-known bastnasite deposits behave differently and therefore would rank differently. Monazite is another example. Processing of primary monazite (rock) is very different to that monazite within beach sands being processed as a by-product of industrial minerals production. There are other factors that can cloud any analysis. You have to look at them all.
Remember last week I stated that we are looking at success factors “today”. Next week, I will look at what I consider to be the second most important success factor. I would be interested in any comments between now and then to see if you and I are on the same page.
Mr Mackowski is a qualified engineer in mineral processing with over 30 years technical and operational experience in rare earths, uranium, industrial minerals, nickel, kaolin ... <Read more about Steve Mackowski>