I agree with you. No silver chloride is generated during the inquartation process. Salt is the cheapest reagent to drop silver from silver nitrate as Silver Chloride and if you have clean Iron or Steel washers (used for fastening nuts and bolts), the silver recovery as cement silver is faster than any other method thus saving cost on using copper to cement silver for AgNo3 solution.
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and again Ammonia to recover silver, you need to abate the obnoxious fumes it generates instantly in the air, and if any acid lying around uncovered in a nearby processing zone it is more rigorous. It spreads in the work area like a wildfire. A small quantity of diluted ammonia we use for cleaning undissolved granules with a Silver Chloride layer and a small quantity for an intermediate wash to remove any Silver Chloride that may have passed through while filtering the Gold Chloride solution to the precipitation unit. You can recover the silver dissolved in Ammonia later.
Salt drops silver as a chloride and tumbling chloride with the steel washers in dilute sulfuric is one approach. But you are forgetting the fact that jewelers see a lot of scrap with platinum findings or white gold with palladium. Any of these metals will remain in solution if you drop the Silver as a chloride. The way you will recover the PGM's is by cementation on copper. So you see you will need to buy that damn copper anyway. Cement the silver on copper and you will collect the PGM's too. As your silver stash grows you can process the extras through a simple stainless bowl silver cell. The slimes generated in this process will contain the PGM's which you can recover by processing the slimes.
First the silver is too costly now the copper is too costly. Refining has it's costs.
First the silver is too costly now the copper is too costly. Refining has it's costs.
Not too much later I have seen refiners leave their silver in ammonia rinses and forget about them. This is dangerous, a client once did this, he was pretty messy anyway, but a dried out bucket formed silver fulminate and blew the wall out of his refinery. Nothing to mess with. Always acidify your spent ammonia when you are done with the batch.
100% true. Copper to reduce Silver from AgNo3 is the best if the Gold scrap contains white metals such as Pt or Pd and for that matter any PGMs that are not soluble in Aquaregia. Also, you can recover copper from CuNo3 so generated by reducing it with Iron plates. Alternately, sell CuNo3 solution to any chemical factory manufacturing Copper Salts. The best process we use when Silver Chloride generation is a large, use Soda Ash and Dextrose to recover silver as cement silver.
If you have done this successfully I would appreciate it, as would many members here, if you would post your method on the forum.
Yes, we have done this successfully. Built an SS tank or a concrete tank covered inside walls covered with acid-proof tiles. The CuNo3 solution is very dilute due to the several washes you apply to cement silver. On top of the tank. across the length or breadth of the tank, you put iron angles with drilled holes to support the hanging iron plates ( 2,3,4 as you wish) which act as a natural cathode on which copper deposits. Over some time, the solution becomes green showing there is no copper in it, siphon it out and collect copper from the bottom of the tank. Not necessary to do this each time you produce cement silver. Once a fortnight or a month, you can practice this. We used to recover copper powder, melt it cast it into copper bars, and reuse it again for the cementation process.
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Yes, they use commercial machines. They give 999 or 995 gold in exchange whatever you like.
I have never had success cementing copper on iron from a concentrated silver electrolyte after the Silver was dropped with copper. Perhaps it was too concentrated. How dilute is very dilute?
We are trying to produce clean gold to avoid re-refining it after a double parting. The Copper you produce will bring down any cadmium and nickel that may have been in the alloys that dissolved in the parting solution. It will be "mostly copper" but when the gold buyer analyzes your gold it may not be as acceptable to be "mostly gold" because the other metals in the copper used to drop the cement Silver contaminated the insoluble gold.
At least until he learns what he can get by with, I would prefer to instruct the OP to use pure copper to get his gold as pure as possible. He can recover the copper as metal and melt and sell it, or sell off the copper nitrate as it is if there is a market.
Dont know what instruments other than XRF. 995/999 gold with xrf report is accepted by bullions and wholesalers in exchange for jewellery or cash here.
Typically purity by difference is done by ICP or in some shops Atomic Absorption. These instruments measure the impurities in a digested sample and determine their percentage of the entire alloy. It is an entire analytical process with calibration and standards for every batch of samples which is why only large producers use it.
If you are looking for an XRF between .995 and .999 you can do it easily.
the concentration of copper is down to as little as 3-5% making it uncommercial for further use in the production of other copper salts.
unless you want to stamp(hallmark) the refined gold with a 999.9 purity mark, fire assay is the best and internationally accepted referee method of Gold Assay.
Try selling refined gold marked .9999 to a major refinery and they will perform an ICP and charge you to refine it anyway to meet purity standards.
According to the assay text's a fire assay is good to 1 part in 10,000. In all practicality that is hard to achieve. Hence assays by difference and the ICP's dominance in the analytical world.
