Best served to use equitation and chemical parting of the goldCategory: Automotive
Article posted by: Don Monnemonne
G’Day to all, I have some 9k, 14k, gold and plated jewellery that I want to use the ‘Wohlwill’ processes on to extract the gold. I watched a video by Steve I think showing a small bath of AR with a lead anode and a multi pronged cathode being used to strip the gold plate from computer parts. Can I use this method by replacing the lead cathode with a small 24k cathode (24k ring) . I found Nitric acid 70% easy to get only 3 phone calls to find a supplier close to me, bought 2.5 litres for $33.00 aussy $30.50US. A well known German chemical supplier wanted $110.00US delivered for the same quantity, it pays to shop around. Last weekend I did a small experiment with a Pentium 3 CPU. I mixed up 25mls of Nitric acid 70% with 75mls of Hydrochloric acid in a jar and sat the CPU in it within a short period of time all the pins were completely dissolved and the liquid was pale yellow. At the same time I placed a few gold plated items ear rings chains lapel pins in another bath , some of these completely dissolve some left the frame of the original item either nickel or zinc I would think. This liquid turned a dark yellow black colour. Can I do anything with these liquids?. Would appreciate any help you good folks can offer.
You would be best served to use inquartation and chemical parting of the gold. While you may experience some degree of success using a Wohwill cell, they are intended to be used to purify high quality gold, not for parting alloys. If you attempt to run such materials, you're likely to encounter problems that would be greater than simply parting as I recommended.
By careful work, you can accomplish industry standard quality (9995) with acids. That, of course, dictates that you follow established guidelines and proper procedures. Should you desire to improve the quality of gold from this process that, then, would be the desirable application of the Wohlwill Process used to refine gold?
Do yourself a favor and read Hoke's book on refining. She covers the use of electrolytic parting and explains (hopefully to your satisfaction) why you should lose the idea.
Wohlwill Electrolysis
Some customers such as jewelers and other industrial end users require gold that is almost 100% pure, so further refining is necessary. In this case, gold using the Miller process is cast into anodes, which are then sent to an electrolytic plant. The final product is a 99.99% pure gold sponge that can then be melted to produce various end products suited to the needs of customers. The electrolytic method of gold refining was first developed by Dr. Emil Wohlwill in 1874. Wohlwills process is widely used in major gold refineries and in conjunction with the Miller Chlorination process. The Gold Wohlwill Process is based on them solubility of gold and insolubility of silver in an electrolyte solution of gold chloride in hydrochloric acid.
The impure gold is cast into anodes which are suspended in cells, while the cathodes are thin strips of pure gold. By passing an electric current from anode to cathode through the electrolyte solution, the anodes are gradually dissolved and the gold is deposited on the cathodes. Any silver, which is insoluble in the electrolyte and any platinum group metals are precipitated to the bottom of the cells. The sequence takes about two days, following which the gold-coated cathodes are removed, melted and cast into bars. The initial process can produce gold of purity of up to 999.5 parts per thousand, with further treatment bringing it up to 999.9 parts per thousand. The disadvantage of the Wohlwill process is that it is time consuming. Consequently, most gold is refined using the quicker Miller Chlorination Process. Where gold of 999 or 999.9 parts per thousand is required, electrolytic facilities at many refineries have been added.
Posted By: Don Monnemonne
Web: http://www.marblecrusher.net
Contact: e-mail
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