My first time, she and I were both about 14 or 15 and..................
My first time working with gold, chemically, was in purifying a large gold electroforming bath in a company I worked for, 52 years ago. The 50 gal gold bath ran 4 tr oz per gallon and was used to electroform gold slip rings about 1/8" thick. It was a cyanide solution and the gold itself was added in the form of PGC, KAu(CN)2. Today, the bath would cost about $300K. Back then @ $42/oz, it was about $10K. The slip ring base was a potted resin and, since it took about 24 hours of plating to get that thickness, organics would leach from the resin and would contaminate the bath. Before I started there, they would make up a fresh one every couple of months and have the old one refined. Of course, they got screwed on the refining and had to pay the PGC premium on the gold. It was expensive. I discovered that by evaporating down about 1/4 - 1/3 of the bath every couple of weeks, the PGC, having a much lower solubility cold than hot, and with the other chemicals in the bath having a quite high solubility, I could precipitate about 90-95% of the PGC in a very pure form. The remaining PGC in solution was sent out for refining. All in all, it saved a lot of money.
I've already discussed this at least a couple of times. My first time refining was at another company I worked for, still in my 20's. Half the building was the largest gold refinery W of the Mississippi and the other half made up the Western Division of the largest seller of PM plating solutions and equipment in the world, at that time. I was the head chemist for both, although I had never refined an oz of Au in my life. The refinery had a Wohlwill gold purification set up, but, because of too much impurities building up in the solution, they were having trouble getting the 99.99% Au purity that they had to have to be able to use the refinery gold in making PGC for the plating baths they sold. At that point, there were having to buy, at a premium, 4N Au on the open market. My 1st thought was to add a certain form of EDTA, as a liquid, to the solution to chelate the metal impurities and prevent them from co-depositing. I took a sample and added a little EDTA to it. To my disappointment, all the gold dropped out!
However, after thinking about this for the rest of the day, I saw the possibility of a new method of refining gold. I experimented for 2 or 3 weeks and came up with a viable production method. During that time, I sent quite a few samples out for a full spectro analysis and every sample I sent out came back at least 4 Nines. We scrapped the Wohlwill cell and started producing nothing but 4 Nines gold in the refinery using my process. The only problem was that, if the refiners didn't follow the process to a tee, the solution was guaranteed to foam over, big time. After another couple of weeks with a lot of foamovers, I fine tuned the process, retrained the refiners, and all went smooth after that, with only an occasional foamover. I would guess that, in the 4 or 5 years they used it, about half a million oz of 4N Au was produced. The company was bought out by Occidental Petroleum and they soon destroyed it. I think it ended up being owned by Ford before it failed completely.
