Question

Mac Arthur process is used for the extraction of:
(A) Ag
(B) Fe
(C) Cl
(D) ${O_2}$

Answer 1

The MacArthur-Forest process is a hydrometallurgical technique for extracting gold from low-grade ore by converting the gold to a water-soluble coordination complex. It is the foremost commonly used leaching process for gold extraction. It is now the foremost important and widely used process for extracting gold from ores.

Complete answer:
Cyanide process or MacArthur Forrest Process: This is used for extraction of Ag and Au. It is supported by the fact that gold/silver dissolves in dilute solution of cyanide in presence of atmospheric oxygen with the formation of complex cyanide.
We can also stick to the definition of the process that is the Process of dissolving powdered gold and silver ores in a weak solution of sodium cyanide or potassium cyanide. The expensive metals are precipitated from solution by zinc which is also known as cyanidation.
Let us understand the process, the Cyanide process is sometimes referred to be a method for extracting gold from its ore. The ore is first finely ground and should be concentrated by flotation, if it contains certain impurities, it's going to be roasted. It is mixed with the dilute solution of cyanide while air is bubbled through it.
The gold metal is oxidized and forms the soluble complex ion. Silver, usually present as an impurity, forms an identical soluble ion. The solution is separated from the ore by methods like filtration, and therefore the gold is precipitated by adding powdered zinc.
The precipitate contains silver which is also a precipitated and unreacted form of zinc. The precipitate is further refined, by smelting to get rid of the zinc and by treating with aqua fortis to dissolve the silver.
Hence, the correct option is option (A), Silver ($Ag$).

Note:
Here the role of oxygen should be noted. Oxygen is one of the reagents consumed during cyanidation, and a deficiency in dissolved oxygen slows leaching rate. Air or pure oxygen gas are often purged through the pulp to maximize the dissolved oxygen concentration. Intimate oxygen-pulp contactors are wont to increase the partial pressure of the oxygen in touch with the answer, thus raising the dissolved oxygen concentration much above the saturation level at atmospheric pressure. Oxygen also can be added by dosing the pulp with peroxide solution.