Some Basic Principles Of Organic Chemistry Question 223
Question: Which one of the following ores is concentrated by chemical leaching method?
Options:
A) Argentite
B) Copper pyrite
C) Cinnabar
D) Galena
Show Answer
Answer:
Correct Answer: A
Solution:
[a] In this process, the finely divided powdered argentite or the native silver or gold is treated with a dilute solution (0.5%) of sodium or potassium cyanide while a current of air is continuously passed.
As a result silver ores pass into solution forming their respective soluble complex cyanides while the impurities remain unaffected which are filtered off.
$ 4Ag+8NaCN+O_2+2H_2O\to 4Na[Ag{{(CN)}_2}]+4NaOH $
$ Or $
$ Ag_2S+4NaCN\to \underset{sodiumdicyano,\text{argentate(I)}}{\mathop{2Na[Ag{{(CN)}_2}]}},+Na_2S $
