However, I have noticed some different colors showing aside from brown. I have black. Blue and green. Any idea what these other colors may be? The solubility of gold, wether by strong acids, cyanide, bromines, etc is a pH dependent reaction. Changing the pH is one way to accelerate or reverse the reaction others exist. The colors are probably due to other metal ions present.
If you want to leach gold you need an oxidizing environment add chlorine gas or clorox until you reach an ORP of mV, at a Ph of about 5, hopefully warm temperature and you will leach gold. Read chemistry papers between to 's Lye is sodium hydroxide.
But the real problem is that your precipitant will not work if chlorine or any other oxidizer is present in solution. You are right of course. I forgot to mention that the solution has to be free from chlorine and oxidizers first. Do not use too much or it will take longer to evaporate. If the color turns blue, brown or black, there is still gold dissolved in solution. If there is gold in the solution, go back and refine a second time. Otherwise, you're ready to decant your solution. It's now time to gather your gold.
Decant the precipitate out of the container, making sure to leave your gold particles inside your container. When using sodium metabisulfite, it's best to save the waste solution for a period of several days or weeks. Gold will settle out of this solution during this time.
While it is the cheapest precipitant, it's also the most expensive to use. Unlike some other precipitants which forms large clumps of gold, the gold particles rendered from the use of sodium metabisulfite is often small. However, if you are very careful while decanting the solution at that time, you may be able to recover most of this lost gold. If using either ferrous sulfate or Quadratic, you can either decant the solution or filter it, whichever you feel most comfortable with.
Quadratic is a little easier to work with than ferrous sulfate because the particles are heavier and larger, and so they settle to the bottom more quickly and tend to stay there. Part 3: Rinsing and Ensuring Pure Gold. Call us at Could you say this where a simple non chemist can understand? Poe, Help me understand this, if any Joe smith had said what you said here I would say that was a big pile of horse-pucky, but since you said this I feel I must either not understand what your saying or need more study of the chemistry involved here.
Joined Oct 7, Messages 2, I am under the impression that it's the sulfur dioxide that is liberated from metabisulfite that precipitates gold. Please correct me if I'm wrong. Not only does some silver chloride dissolve in acid HCl , but also NaCl and just about any heavy concentration of the chloride ion.
It's plain water and aqua regia where AgCl is least soluble. But there is something way more important to discuss than the solubility of small amounts of silver in strong solutions of nitrogen expelled ex-aqua regia: It's the danger of oxalic acid or it's salts! If one neglects to remove the silver chloride from the gold solution, then reduces the gold with oxalic or one of it's salts, a compound of silver oxalate is formed.
Left with the gold powder, it helps with coagulation, BUT! It explodes when an attempt is made to cupel or melt it! The tiniest bit will at least cause your bead to jump out of the cupel into the furnace. A larger amount could kill or maim. To elaborate further: When a sufficient amount of silver is alloyed or mixed with platinum, the two dissolve together in nitric acid. Platinum, which doesn't dissolve normally in nitric acid, combines with silver nitrate. When aqua regia or salt, or just about any chloride is added to the acid, the opalescent silver chloroplatinite is formed and not the very insoluble silver chloride.
This is one way that silver can end up in a solution the same time as gold. If one happens upon a solution of gold, platinum and silver, I suggest that you add more aqua regia and heat strongly until the platinum gives up the chlorine-silver for nascent chlorine, allowing the silver chloride to precipitate. As far as an explanation for a sulfur dioxide smell, you use too much. The oxidizers are first reduced by the SO2, remaining nitrates, peroxides, tellurides, etc.
Then the gold chloride. What is left in the solution is hydrogen sulfite, H2SO3 which decomposes into water and SO2 gas when heated. They only way that I will believe you can efficiently precipitate gold in the cold Or room temperature is when the solution is heavily concentrated! Even then some is bound to precipitate colloidally. Geo Well-known member. Harold; First of all, I believe that 18 oz of gold in 4 liters of solution IS considered concentrated.
Secondly; colloidal gold is formed in a multiple of colors. Not just purple. I will post a picture of the various colors from transmitted light as well as from reflected light as soon as I learn how to post a picture here. Clicking on the Img doesn't seem to work for me. I need schooling in computer savvy. If exothermic reactions get too hot, try slowing down. I can see adding ice to cool a hot reaction, but to precipitate in the cold, ridiculous. I really thought that you guys were participating in a joke on me.
Ha Ha. I found by further probing into the forum to my astonishment that you guys were serious. I almost regret to show you what you obviously have seen thousands of times. Oh, by the way, colloidal gold is unaffected by stannous chloride or any reduction agent. Coagulation by anode DC current. If you are like most of the refiners that I knew, you have a 'catch barrel" where you toss your "spent solutions". My work as a research chemist for Trans-Ore Research was to assay, analyze and 'break' refractory ores from all over the world.
These were ores that gold could be seen under microscope, yet resisted all efforts except mine to process. I excelled in solvent to solvent extraction. Which reminds me, you can shake alcohol with colloidal gold as well to bring it down. Now I am going to humble myself a little bit here: As a refiner of natural ores, I'm world class, yet as a refiner of scrap metals, you probably have more experience than me. The question is: Which is more difficult?
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