Leaching Gold with H2O2
Gold Leaching / Gold Recovery from Natural Gold Rocks
Gold Recovery from Gold Rocks and Ore

Gold Recovery from Gold Rocks and Ore

natural gold rocks
Leaching Gold Rocks using Hydrogen Peroxide
Gold extraction from natural gold sources, including gold ores & gold rocks, can be done by leaching the crushed gold rocks or gold concentrate, in a solution of hydrochloric acid and an oxidizer.  There are a number of oxidizers that can be used to put the gold in solution.  For example, as previously discussed in our article titled Refining Gold with Aqua Regia, nitric acid was used as the oxidizer to extract gold and other precious metals from natural gold rocks, computer scrap and old jewelry.  Aqua Regia however, with its nitric acid, has some disadvantages when leaching gold ore.  The nitric acid in aqua regia tends to dissolve many unwanted minerals and other contaminants which can cause problems when it comes time for the precipitation of gold, platinum and palladium. Leaching gold with aqua regia also requires additional steps to neutralize the nitric acid before recovering the gold, especially when the gold is recovered with ion exchange resins or the precipitation method.    
  
This article will discuss an improved gold leaching formula that uses hydrogen peroxide as the oxidizer to leach and then recover gold, platinum and palladium.  Using hydrogen peroxide, or H2O2, has many advantages over Aqua Regia, both durring the gold leaching process and durring the gold recovery and gold separation phase.  A hydrogen peroxide gold leach is useful with the newer advanced gold recovery methods, such as Solvent Extraction and the use of ion exchange resins because there is no Nitric Acid that needs to be neutralized first.  

Gold Leaching

Gold Leaching

Gold extraction from natural gold rocks
Hydrogen Peroxide Gold Leach Formula
Concentrted H2O2  and HCL are used to create a powerful gold and precious metal leach, with the H2O2 being slowly added over a period of time. Depennnding on the makeup of the gold rocks or gold ore being leached, the H2O2 & HCL ratio can be as low as 1:10  
One advantage that the H2O2 gold leach has over other gold leaching formulas is that this gold leach will leach gold, platinum and palladium and do it at room temperature.  No heating is required.  This helps to keep the gold recovery costs at a minimum.

The hydrogen peroxide / HCL gold leaching formula also produces fewer NOX gasses.  Dangerous chlorine and other gasses are still produced however, and a fumed hood and appropriate sized scrubber need to be used when using this leach as with all other chlorine based leaches. 
   
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Gold recovery
Gold Extraction, Separation, & Purification
To extract gold and separate the gold from the other precious metals and base metals, you would normally have to neutralize the nitric acid in an aqua regia leach, but with the H2O2 gold leach, there is no nitric acid to neutralize, or boil off before separating the gold. This is a big advantage when using the H2O2 / HCL leach formula.  This gold leach saves a lot of time when compared to other gold leaching formulas that use nitric acid as the oxidizer. 
  
With the gold in solution, the gold extraction from the other base and precious metals can be accomplished in a number of ways.  A common gold extraction method is to precipitate the gold by adding a precipitant to the gold leach solution.  This causes a reaction to take place in which the gold ions are reduced and accumulate into larger particles that fall out of solution.  This gold precipitate can now be easily filtered and the gold recovered.  Some of the more common gold precipitans are Sodium Metabisulfite, Oxalic Acid, Zinc, Hydogen sulfide, Iron Sulphate, Hydroquinone, and Sulfur Dioxide. 
 
The precipitation of gold and other precious metals can be precipitated out together or as individual metals depending on the precipitate used.   Zinc for example will precipitate gold and platinum group metals all at once, where sodium metabisulfate will only precipitate gold.    
Natural gold rocks and ore

Natural gold rocks and ore

Natural Gold recover
Pure Gold from Natural Gold Rocks & Gold Ore
The final step in the gold recovery process is to heat the dried gold precipitate up to 2000 F.   A little Borax can be added to the gold precipitate, but is not necessary.   Once the gold precipitate has melted it can be poured into a mold or into a container filled with water to obtain gold shot. 
 
The process of gold extraction from natural gold rocks is very rewarding.  Finding gold and the extraction of gold is within the grasp of most people as long as good safety rules and precautions are followed and the proper equipment is used.  A good book for those interested in gold recovery techniques is Recovery and Refining of Precious Metals, by C.W. Ammen. It is available at Amazon.com