![]() ![]() Learn to make your Aqua regia when dissolving gold with limiting the amount of nitric acid using only the amount of nitric acid needed and no more, this way you do not have nitric acid (oxidizer) to eliminate, when you do have some free nitric acid to remove use the evaporation process, evaporation and an added gold button, or sulfamic acid, to remove free nitric from your solution.Īqua regia is a difficult to master, and needs understanding and practice to be able to use it, reading about it seems like a simple thing to use, but in reality can have many difficulty's for a beginner, solutions can be boiled over easy from the reactions, or during evaporation process when nitric in solution is concentrated, people will say you can dissolve any metals with your gold and make it sound simple to get your gold back, the internet is full of miss-information or missing facts, and either mislead you in your thinking or do not tell you the whole story or are just plain bunk, there are other methods to dissolve gold, especially when gold is in flakes, powders or foils or finely divided state, like HCl/NaClO (bleach), or HCl/32% H2O2, there are other solutions but these are the one you will want to learn about.Ĭopperas (ferrous sulfate) (FeSO4) has probably been used more throughout history than sodium metabisulfite (SMB) to precipitate gold, and works just as well sometimes better depending on circumstance, ferrous sulfate can be made at home easily (I have many post on how),if you buy your ferrous sulfate as a garden supplement it could be oxidized (brown), if it is brown do not use it will not work, the crystal salts of ferrous sulfate should be a pretty green color salt, the brown is oxidized iron salts and no longer copperas good to use to precipitate gold, using any precipitant to recover your gold is best used with testing, using your stannous chloride to help you determine the end point or if the reagent is needed or would even work, most of the reagents as a general rule use about as much in weight of reagents as gold in solution, copperas and SMB are not the only reagent that will precipitate gold from solution, each reagent will normally reduce other metals besides gold from solution (although most are fairly selective), here is were you will read in Hoke why she may choose one over the other depending what other metals may be in solution or where she will use a different reagent on the second refining to purify the gold as the different reagent used on the second refining would nor precipitate the same base metal the reagent in the first refining did. ![]() You need Listen to your sister, she is correct urea and nitric can make dangerous compounds especially with metals and processes we use, many will suggest urea to de-NOx a solution, I never do, not only because of possible danger, but you add another impurity, urea will not destroy nitric acid, as most people who recommend its use believe, it will destroy nitrous acid or NO2 in solution, actually urea is often added to fuming nitric acid, for this reason when they want pure nitric acid free from NO2, the urea does not destroy the pure nitric acid, but removes the NO2 gas from the pure HNO3. There are many things you will need to learn here, fist you should study Hokes book.Īqua regia should be used to dissolve gold, not base metals or gold and base metals.
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