Gold Extraction

The dissolution of gold in ammoniacal solutions cannot take place in the absence of oxidants. Cupric ammine can act as an oxidant in this system according to Equation 3.

The effect of cupric ammine concentration on the dissolution rate of gold was investigated in a solution of 0.6 M total ammonia concentration (0.1 M (NH4)2SO4 and 0.4 M NH3). The cupric ammine solution was prepared by adding known concentrations of copper sulfate (CuSO4.5H2O) and free ammonia in the ratio of 1:4. Figure 2 shows the Tafel polarization curves for the dissolution of gold at different cupric ammine concentrations. It can be observed from these curves that the dissolution potential of the system increases with the increase of the concentration of cupric ammine. Therefore, cupric ammine can be successfully used as an oxidant for the dissolution of gold in ammoniacal solutions.

It can also be seen from the curves in Figure 2 that variation in the cupric ammine concentration had no effect on the anodic portion of the curve. This suggests that cupric ammine has no effect on the anodic reaction which is given by Equation 1. Hence, it ….Read more

Flotation

The simplest method of treating a carbonaceous ore is the method described by R. W. Nice (1971) at the McIntyre Porcupine Mine where the carbon, which contains very little gold, is floated off and discarded. The remaining ore is then responsive to cyanidation. This does not work at Carlin because the carbonaceous compounds have a high gold content. A considerable amount of flotation work was done on Carlin ores, however, to produce a high grade concentrate for possible shipment to a smelter and a tailing which could either be discarded or directly cyanided. All of the concentrates contained both carbonaceous material and pyrite and showed low recoveries of gold and poor selectivity. This was because of insufficient liberation of carbonaceous material and sulfide from the gangue, even at 100 per cent minus 325 mesh.

In the treatment of an auriferous sulfide associated with carbonaceous shale from South Africa by American Cyanamid Company (1939), up to 77 per cent of the carbon was eliminated by depressing it with Cyanamid reagent 637 while floating the sulfides for 90.5 per cent gold recovery, and 20.4 to 1 ratio of concentration. Fortunately, the carbon in the Witwatersrand ores is in a form which ….Read more

So tonight’s topic of interest is kind of near and dear to me, I’m going to start with the first slide; Rocks and Gold Clues. What rocks tell you about where to find gold, there are clues that they give and those are very important if you’re going to find gold and that’s what we’re here for; right? Hi, I’m Prospector Jess; this is another hangout regarding gold prospecting and how to find gold. I just want to make sure that everybody is in tune with where were going. The adventure for tonight is about rocks and gold and how the two are connected together. I have a background in geology and engineering, primarily from UCSD. I have been an engineering manager for a number of years and then more recently I’ve been doing work helping with gold prospecting. The gold prospecting part I started it as a family adventure but actually it’s deep in my roots, my great-grandfather was a prospector in 1849. So it’s one of those things where I learned about it as a child and then learned again when I had children. And I think it’s important to recognize that a certain amount of excitement and ….Read more

I told you I wanted to do a panning video. So what you’re going to do is, I’m going to break this down a little bit differently. I’m not going to get real scientific on this; I’m just going to put it in plain terminology. Now unfortunately we are probably going to listen to gunshots down the road because its deer season and everyone is getting sighted in. But I am going to show you this, I am going to try and keep it simple but it really is hard to keep panning simple, I am going to warn you about that now. So if you don’t want to watch a pretty in depth panning video, go away, shut this off, and don’t watch it. But I figured I would show you a couple different tricks, I am going to show you some techniques, I am going to show you some things that I like to do. And panning is not something really you can just pick up a book and read on it’s something that comes with practice, so you really need to practice. And of course you can practice with cons.

Now the nice thing about practicing with our ….Read more

During the past 50 years or more there has been a great waste of money, energy, and time in devising, building, and trying many machines to recover gold and platinum, also gemstones, from black sand. Volumes have been written on the subject, and many inquiries have been made by prospectors and others who thought that although they could not save the precious metals, which most likely were never there, some process must be suitable. Near Nome, Alaska, the black sand was rich, and some on the west coast of the South Island of New Zealand is being worked at a profit at the present time. A few spots along the California- Oregon coast were worth handling, as have several along the rivers in the western United States and Canada. The black sands from sluicing and dredging operations are worth careful treatment because they are from the concentration of thousands of yards of gravel daily. By-product black sand from inland placering is often richer than beach sand. But generally, black sand, unless a concentrate, is not worth much effort. In any case, it is worth spending a dollar or two to have an assay made for gold of a carefully taken ….Read more