May 22, 2010· "Solution for precipitating gold from HAuCl 4 solution" A discussion started in 2005 but continuing through 2019. 2005. Q. Respected Sir, My technical problem is how to precipitate gold from HAuCl 4 solution. We recover gold from Filings, Setting, Waste water, Consumables used in production, Emery papers, and sweeps from the production floors.