Finished off the oven work for converting the MgSO4.7H20 to MgSO4, or at least I think I did. My kitchen scales are so vague I could be slightly out.
Best that I can tell it all worked though.
Also went to the supplier to get some Steel Ball Bearings to pulverise the MgSO4 into fine powder but they were out of stock. Ordered them anyway and will await their arrival.
Next task in the interim is to figure out how to make myself a Ball Mill. As I have no useful motors lying around I think I will try and sneak some time in, using the Food mixer's Power take off to drive the Mill.
Just need to make the rest of the Mill now.