If I was Christopher Ellison, page-63

I'll set you straight. Ta and Li are both found in the same rock type, pegmatite. The pegmatite is mined the same and often contains both Ta and Li (we may yet find that the Ta peg also contains Li but was not analysed for it back before Li was in vogue). The process stream is different for ta and Li. Li normally requires a fine crush/coarse grind and then treatment through a DMS circuit. Ta normally requires finer grinding and gravity treatment via some combination of knelsons, jigs, spirals and tables because it is normally much finer than spodumene and is also much denser (with an SG of >8; compared to spod = 3.1). The radioactive tailings can be produced from both streams and is caused by the pegs often containing rubidium, potassium and minor Th and U.