In gold mining one of the most used processes for metallurgical extraction is the Merrill Crowe, named in honor to his creators Charles Merril and Thomas Crowe around the year 1900, in this article I will describe briefly how this works and the equipment used in it.
The main objectives of this process are obtain the highest amount of values once the precipitates of this process are melted, and also minimize the amount of values in the slag.
The process of precipitation of gold and silver begins with the clarification of the pregnant solution coming from previous processes, such as heap leaching, this clarification is usually done in leaf filters which contain metal meshes covered with a cloth of synthetic filter.
Once filtered, the rich solution go to the deoxygenation tower, this element removes the dissolved oxygen from the solution mechanically, creating a high vacuum, this process is very important because in the presence of oxygen the precipitation of the values it may not be efficient
In the next step, Zinc powder is added, this starts a chemical reaction of oxidation / reduction, where the gold coats the Zinc particles together with other compounds such as silver and mercury.
The solution is passed through filter presses from which the gold and silver precipitate is obtained and will be melted in the re cake oven where the mercury is extracted, and mixed with fluxes, then sent to the induction ovens where it is melted to separate the gold and silver values of other base metals, and the final product called Doré is poured into molds to form bars and prepare it for shipment.
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