question, page-6

which part do you need to clarify? Your basic heavy mineral sand contains a bunch of heavy minerals, some of which can be used to extract stuff like titanium, rare earth elements, and zirconium. A gravity circuit can further enrich these and chuck out light minerals that are diluting what you want. But there are still non-titanium and Fe bearing minerals there. You can get the magnetite very easily becuase it is already magnetic. But here they seem to have found a way of making normally nonmagnetic titanium-bearing minerals magnetic, so that you can fish them out preferentially too. But even more interesting is the idea that this magnetising process opens the mineral to leaching by HCl......but exactly how, I am uncertain.