Chemical Formula

Chemical Formula to Dissolve and Precipitate Metal

All, there seems to be a lot of confusion on the various acid mixtures used in the different reactions. Here's a quick Chemical formula to dissolve and precipitate Metal :

1.AR= Aqua Regia = 1 part 70% Nitric Acid, 3 parts Muriatic Acid (some guys use 4 parts muriatic). Used to dissolve high karat gold, gold powder, gold foils, dissolves Platinum when hot. Excess nitric must be neutralized with Urea to pH 1 +/- 0.4, then drop gold with SMB (Sodium Meta Bisulfite).

•Hoke states 4 fluid ounces HCl + 1 fluid ounce HNO3 dissolves 1 troy ounce gold. This is equivalent to 31 mL HCl + 8 mL HNO3 per gram of gold.

2.AR Recipie 2= Poor Man's AR = 8 oz Sodium Nitrate, 480 ml water, 960 ml Muriatic Acid plus heat. Used to dissolve high karat gold, gold powder, gold foils, dissolves Platinum when hot. Excess nitric must be neutralized with Urea to pH 1 +/- 0.4, then drop gold with SMB.

•The above mentioned recipie makes enough AR to dissolve 160 gm Pins or 32 oz of ceramic cpus.

3.HCl-Cl= Clorox Method = 4 Parts Muriatic, 1 Part Clorox (added in small increments). Used to dissolve gold foils and powder. Drop gold with SMB, NO urea needed.

4.AP= Acid Peroxide = 2 Parts Muriatic Acid, 1 Part 3% Hydrogen Peroxide. Dissolves base metals, slowly dissolves gold when heated. If gold is present drop with SMB, NO urea needed.

5.Dilute HNO3=Dilute Nitric Acid= 1 part water, 1 part 70% Nitirc Acid. Used to inquart, dissolve base metals, dissolves palladium, and dissolves silver. Silver nitrate will stain skin blue which turns black in sunlight. Skin remains black for nearly 1 week.

•Hoke states 4-6 pounds of concentrated nitric acid dissolves 1 pound of base metals. 5 pounds of 70% nitric, 1.41 sp.gr. is 1610 mL =~ 0.425 gallons.

6.H2SO4= Sulfuric Acid = 1 cup 96%+ Sulfuric, 1/8 tsp glycerin. Used as electrolyte in electrolytic cell along with a small amount of glycerin. Effective on medium to large gold plated items. With specially designed anodes and cathodes large batches of smaller plated items can be processed. Not used for Gold filled or karat jewelry.

•Use until acid is saturated with black powder typically 12-24 hours of operation. Sink any floating black powder, let settle overnight, pour off bulk of acid for reuse, and dilute remaining acid with 4 parts water.

7.HCl= Muriatic Acid = 31.45% Hydrochloric Acid. Used in the crockpot method and for general cleanup of gold foils and powders. Dissolves base metals. Also used in making stannous chloride gold testing solution.

8.SMB= Sodium Meta Bisulfite plus water=28.3 Grams Sodium Meta Bisulfite, 240 ml H2O. Used to precipitate/drop gold from gold bearing solutions.

•Add 65 grams to 100 ml water for saturated solution. Add to pregnant solution until stannous chloride test on solution is negative for gold.

9.AuCl3= Auric Chloride= Term used to describe gold dissolved into solution. Typically imparts a golden yellow color to solutions. Stains skin and other organics purple.

10.SnCl2= Stannous Chloride= Used to test solutions for precious metals. Made by dissolving metallic tin in hot muriatic acid. Loses strength when stored. Stannous Chloride, SnCl2.2H2O.—The crystals are best purchased. If kept dry and free from air they are fairly permanent. A solution is made by dissolving 20 grams in 10 c.c. of hydrochloric acid and diluting to 1 litre. The solution is not permanent. It is a strong reducing agent, and is chiefly used in solution for this purpose.

Positive color test as follows:

•Purple/Black color is Gold in solution, the darker the spot the more Gold.

•Yellow/Brown color is Palladium in solution, the darker the spot the more Palladium.

•Light/Dark Rose color is Platinum in solution, the darker the spot the more Platinum.

11.(NH2)2CO= Urea= 8 oz Urea, 480 mL Water. Used to neutralize excess nitric acid in AR process before dropping gold with SMB. Add until solution doesn't fizz and pH reaches 1 +/- 0.4.

12.AgCl= Silver Chloride= White precipitate that forms when silver is exposed to chlorine in solution. Turns purple in light, darkens further in sunlight. Solid by product of using AR on lower karat jewelry. Hazardous to melt due to fumes. Production of silver chloride should be avoided if possible. Can be converted to silver metal with lye and karo syrup or HCl and Al foil.

•For 1 tr.oz. of silver metal, about 41.5 grams of silver chloride, it takes about 20 grams of sodium hydroxide, 13.3 mL of light Karo syrup, and 133 mL of water.

13.Inquartation= 3 parts base metal (Silver perferred) , 1 part Gold, Dissolved in hot dilute nitric acid. Powder/Honeycomb that remains is Gold and higher PGM's if present in source material. Left over liquid contains Silver, base metals, and Palladium if present in original alloy.

•Hoke states 4-6 pounds of concentrated nitric acid dissolves 1 pound of base metals. 5 pounds of 70% nitric, 1.41 sp.gr. is 1610 mL =~ 0.425 gallons.

11.C12H26O3 = BDG or DBC= Butyl DiGlyme or DiButyl Carbitol = Organic solvent that combines with Auric Chloride and is insoluble in water based solutions. Separates from water based solutions as an upper phase (layer). After washing with dilute HCl gold is dropped as flakes using Oxalic Acid. Can be used on AR solution without neutralizing excess nitric acid.