Question

Which of the following is cyanide process?

• A. MacArthur Forrest process
• B. Gold Cyanidation
• C. Both a and b
• D. None of these

Answer 1

The correct option is C

Both a and b

MacArthur Forrest process or Gold Cyanidation or cyanide process are just different names for extraction of gold. During this process finely powdered ore are treated with sodiumcyanide as a result gold dissolves and forms sodium dicyanoaurate (I) complex which in turn is reduced by Zinc to form corresponding gold.

$4Au$ $+8NaCN$ $+O_2+2H_{2}O$ $\to$ $4Na\left[Au\right(CN{)}_2]$ $+4NaOH$
(Sodium dicyanoaurate (I))

$A{u}_{2}S$ $+4NaCN$ $\to$ $2Na\left[Au\right(CN{)}_2]$ $+N{a}_{2}S$

$4N{a}_{2}S$ $+2H_{2}O$ $+5O_2$ $\to$ $2N{a}_{2}S{O}_4$ $+4NaOH+4S$

$2Na\left[Au\right(CN{)}_2]$ $+Zn$ $\to$ $N{a}_2\left[Zn\right(CN{)}_4]$ $+2Au$ (Gold)