Reducing any raw material in size is typically the most expensive part of any dry processing system. This is due to the amount of energy required to breakdown larger particles into smaller particles. So if you can reduce the amount of material that has to be subjected to milling, grinding or micronizing, then you will likely be able to save valuable dollars in energy cost. One effective way to do this is to utilize high-efficiency air classifiers. If the percent of fine product in your raw material stream is 20 percent or greater, then it is typically a good candidate to air classify ahead of size reduction.
Sturtevant and Komarek have developed a process for lithium carbonate milling/micronizing that implements this critical process feature. In the processing of lithium carbonate, dryers are needed to dry the lithium that has been extracted from the salt brines. Whether using a fluid bed dryer, that has a vigorous up and down fluidization action or rotary drum dryer that has a tumbling action, the process of drying will typically produce approximately 40 percent of fines that have a finished product particle size of d90 at 11-12 micron. This can be great news or not-so great news. Until now, it has been not so great news. Dealing with product size fines has added greatly to both CAPEX & OPEX in the processing of lithium carbonate.
Processing lithium carbonate with a high percentage of product sized fines adds greatly to the energy cost of processing lithium. First, the fines will produce a cushioning effect that prevents most any mill from operating efficiently. Secondly, why subject a raw material stream that has 40 percent good product to high energy milling/micronizing when you can utilize low energy air classification to capture the product. Lastly, you can utilize a much smaller compactor that no longer requires ancillary equipment such as mixers (no added water), hammermills or vibratory screens.
The research and development work we performed in our lab in Hanover, MA proves out this point. We were able to produce battery-grade lithium carbonate with a nominal d50 of 4-5 micron and a nominal d90 of 10-11 micron at half the horsepower requirement of most lithium carbonate processing operations.
Contact us for more information on saving CAPEX and OPEX by pre-classifying lithium carbonate before milling or micronizing.