hello pls explain more what do you want from hematite grinding?

Hi Johannes - I don't have any direct experience with this, but if "micaceous" and "lamellar" mean that your are liberating flat platelets, then you might think about separation using a shaking table.  I have done this for various mica minerals.  The flat particles tend to stay on the table and work their way to the concentrate side, while the round particles will bounce over the riffles and work their way to the tailings side.  You could look at taking the mill discharge and running it over a table, and then either sending the tails to a cyclone, or back to the mill.  You can quickly try this in the lab with a lab mill and a small table.  Setting up a shaking table is more art than science as there are several variables to play with, so don't be disappointed if you don't get a great separation the first time around.  The table will also sort on particle specific gravity, so you might be able to separate non-iron (i.e. lighter) minerals on the table as well - it is not unusual to make 2 or more separations on a table.  The down-side is that that shaking tables have pretty limited capacity.  My guess is that the micaceous material is quite friable, so pulling them out of the circuit will be critical to avoid over-grinding.  You should use a rod mill in the lab to avoid over-grinding, and also think about using a rod mill when you go to full scale production, simply to avoid over-grinding over the micaceous material.  I hope this helps.  Best Regards - Andrew