I wash beeswax by bringing it to the boil in a pan of water, then letting it cool. the wax floats and sets as a disc on the top and the impurities stay in the water. It's very simple to repeat the process several times until it is pristine again.
To clean the residue from the pan after, warm the pan, wipe well with kitchen paper and then wash in soapy water.
This method can be used for any solid wax or fat, hope it helps someone.