Q.What is tailing of mercury? How is it removed?

Tailing of mercury = mercury losing its clean globular flow due to surface impurities during the amalgamation process of extracting silver/gold; fixed by treating with dilute HNO3.

What is it

In the metallurgy of noble metals like silver and gold, the crushed ore is treated with mercury, which dissolves the metal to form an amalgam (this is the amalgamation process). For this process to work efficiently, mercury must be able to move freely and 'wet' the metal particles, forming a continuous stream of small globules. Sometimes, mercury gets coated with impurities (dirt, or metals like zinc, lead, tin, and other base metals present in the ore) that stick to its surface. This makes the mercury lose its characteristic fluidity/globular property and instead break up into small elongated streaks or 'tails' instead of clean spherical globules. This defect is called tailing of mercury.

Why it is a problem

A 'tailed' mercury surface cannot effectively wet and dissolve the noble metal particles, reducing the efficiency of amalgamation and hence the recovery of silver/gold.

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