Gold refining

I have 4 pounds of scrap gold. I want to learn how to refine it. Any suggestions? Will appreciate your reply.

1. Make up solution => HCl : HNO3 = 3 : 1
2. Make gold to small pieces (about 0.5cm)
3. Put small gold pieces into 1. solution.
4. Boiling (until dissolve out)
5. Boiling continuously...(For NOx out)
6. Add HCl 2~3 times ( HNO3 will disappear and the solution will almost HCl).
7. Add Urea for elimination of the remaining small amount of NOx. Bubbles will be generated (until no bubbles.
8. Cooling the reactor until 80~90 deg. C. then Add Sodium sulphite---> you can see the yellow gold powder.
9. Filtering with warm pure water until pH.
10. Burning them including filter paper at 1000 Deg. C.
11. Melting them with O2 torch. You can get 99.9 up pure gold.