Quick Assays in mineral identification by prof. Walter .A.Franke of Freie University in Berlin

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Quwannar

Active member
Joined
May 26, 2017
Messages
35
Dear Friends;
Here is the url addresses of a document prepared by retired a proffessor, Walter A. Franke of Freie University in Berlin called Quick Assays in Mineral İdentification.
At the 41th page of his document, in order to identify gold in sulphide minerals he defines the fusion protokol of NH4Cl (ammonium chloride) with /NH4NO3 (Ammonium Nitrate) at 142°C.

"Any sulphide ore may be dissolved by the fusion of a pinch of the powdered mineral with a surplus of the mixture of one part ammonium chloride with 2.5 parts of ammonium nitrate. The cooled melt is dissolved in some drops of hydrochloric acid. A drop of this solution is brought to a filter paper and a drop of a solution of SnCl2 is added. A red colour indicates the presence of gold.
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He also describes for panning gold and/ gold concentrates as in forum of hcl/clorox leaching of gold.
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Another procedure may be used in testing for gold in panning residues. Transfer the wet heavies into a glass jar or beaker and decant the water. Now add two pinches of calcium hypochlorite and 3 ml of hydrochloric acid and cover the vessel with a watchglass. Ensure good ventilation, since chlorine evolves due to the reaction HOCl + HCl = Cl2 + H2O. The chlorine dissolves the native gold and soluble HAuCl4 is formed. Wait for 10 minutes, add 10 ml of diluted HCl and shake cautiously. Now transfer some of the solution to a test tube and boil till no odour of chlorine remains. Some drops of a solution of SnCl2 are now added to the cooled solution. The presence of gold is indicated by a purple colour due to a colloidal solution of gold, called "purple of Cassius“. If there is only a tiny amount of gold the colour shows sometimes a bluish purple. Please refrain from weeping for joy in case of a positive reaction: this reaction is extremely sensitive. Already the 1/1000 part of a milligram of gold per millilitre causes a red colour. If no calcium hypochlorite is available it is possible to use chloride of lime CaOCl2 instead. The use of sodium hypochlorite solution is also possible. Such a solution is sold in some countries by pharmacies as "eau de javelle“ for bleaching and disinfection. - Gold can be dissolved also in bromine water. - Add a surplus of solid sodium thiosulphate to any remaining solution in order to destroy any free chlorine or bromine!
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https://www.google.com.tr/url?sa=t&source=web&rct=j&url=http://www.geo.fu-berlin.de/geol/fachrichtungen/geochemhydromin/mineralogie/pdf/quickassay.pdf&ved=2ahUKEwjdvKbgvOfZAhVJ1ywKHZjKDr4QFjABegQICBAB&usg=AOvVaw0AUeXUXQspi9ouyEA7i1eR
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İf we react ammonium nitrate with ammonium chloride at 142 C, Can there be an explosion either in reaction or in cooled melt of post reaction with HCL.
Any considerations would be appreciated.
Erdem.
 
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