Blade was rusty, by physical means and can rusting away. But if the iron surface is not Planar, using physical methods are more difficult. For example for meat grinder blade is a spiral, we would not be able to use a simple method of grinding to rust. Recommended 3 simple methods here for your reference:
1, with fine sand and yellow mud the appropriate mix, stir into the meat grinder, sand and rust in a meat grinder to remove yellow mud. But be aware, do not install the blades or blade damage.
2, to the store to buy some rust spray, spray it can remove rust. But this method can't guarantee subject to rust-toxic, can be cleaned.
3, can rice water soaking meat grinder blade. But need to pay attention to with a very high concentration of rice vesicles in a few days.