Removing white Corrosion on my rice cooker heating element
From your brief description, it appears that you have a deposit of (lime)scale on your heating element.  Scale is mainly calcium carbonate and is commonly formed due to hard water.  It is often found in kettles, coffee makers, etc. which use hard water.
The usual way of dealing with it is to run the appliance with vinegar in place of or in addition to the water.
If what you have is actually corrosion of the element, indicated by dissolution of the element, then I would be hesitant to use the rice maker.