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Hydrometallurgy For Gold Leaching

Refiners hydrometallurgy will give examples of careers and precious metals using chemistry both inorganic and organic, chemical engineering, metallurgical engineering and others. Hydrometallurgy for gold refers the processing techniques that require wet chemistry approaches to separate the precious metals from the surrounding materials vs pyrometallurgy which requires heating and smelting operations to perform the separation.

Hydrometallurgy to take many forms depending on the substrate or the material which contains the precious metals. Many of these chemicals used are very hazardous and these processes should only be done by professional refiners

Hydrometallurgy is an extractive metallurgy process using aqueous solutions to recover metals it involves technologies with solubilize, concentrate and then recover specific metals.

For example a first step maybe to chemically dissolve or leach a material to eventually extract metals by means of precipitation or electrically reducing the metals.  Leaching is the first process used to extract metals into an aqueous solution, chemical acids or alkali eyes are used to convert metals into soluble salts within the solution.

For example aqua regia is a highly corrosive acid mixture of nitric and hydrochloric acids which will dissolve most metals, including gold platinum and paladium

In the other platinum group metals however do not dissolve in aqua regia so it can be used to separate these groups, all those silver also dissolves in aqua regia it immediately precipitates to silver chloride so does not go in the solution. Nitric acid alone is used to dissolve silver.

The different gold leaching processes are descriptively named :

Gold leaching processe
1. Situ Leaching
 In situ leaching also called  solution mining. Extrating the minerals directly from ore in the mining. Leach solutions are pumped through the ore to surface.  In situ leaching is occasionally used in select mining operations to leach precious metals from surrounding rock structures.

2. Heap leaching is routinely used to remove gold from ore deposits in tailings

3.Vat leaching is most frequently used when removing gold from secondary scrap materials such as electronic scrap or even jewelry scrap

See Also : 
How To Work The Heap Leaching Mining  
Gold Leaching Process With Carbon In Pulp

4. Agitated leaching is where the material is saved in slurry with the extracting solution.

5. Pressure leaching places the material, solvent along autoclaves to pressurize heat, it is also used when gases need to be added for the leaching reaction.

The pressure oxidation process the free gold is an example of this cyanidation and chlorination are other pressure leaching processes, after leaching solution concentration and purification steps are employed to further concentrate and separate the precious metals

These refining processes can be used for precious metals extracted from primary remaining sources as well as secondary sources of industrial or recycle scrap materials

Video How To Refine Precious Metals - Hydrometallurgy

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