While it's an excellent idea to recycle scrap, I hope you've evaluated the value of the gold and the amount of scrap. It is done presently in poor countries like Bengladesh where wages are low and health and environment protection law not too costly. The chemical used for gold up to now are yuk.
Maybe it's not the same job to extract a decent gold concentration from scrap and to purify that gold? Many people do already the second step, so you could stop your part before.
Gold purification often uses cyanides and mercury in big amouts. Personnally, I'd avoid both.