Looking for classes? Ksquare Career Institute, Bengaluru →
Concentration of Ores
Concepts tested here
- Leaching of silver ore
All Questions
2007 AIPMT-PRE 1 question
-
Sulphide ores of metals are usually concentrated by froth flotation process. Which one of the following sulphide ores offers an exception and is concentrated by chemical leaching?Leaching is the selective dissolution of the desired mineral in a suitable reagent, leaving behind the impurities.
Argentite or silver glance, $Ag_2S$, is an ore of silver.
Silver is extracted from argentite by the MacArthur-Forrest cyanide process, which is a leaching process: the ore is treated with a dilute solution of NaCN in the presence of air.
$Ag_2S + 4NaCN \rightarrow 2Na[Ag(CN)_2] + Na_2S$
Silver dissolves as the soluble complex and is later recovered by displacement with zinc. Gold is leached in the same way: $4Au + 8KCN + 2H_2O + O_2 \rightarrow 4K[Au(CN)_2] + 4KOH$
Galena (PbS), copper pyrite ($CuFeS_2$) and sphalerite (ZnS) are concentrated by froth flotation.
So the exception is argentite.