India, May 27 -- Four workers died of suffocation after they were sent into a Jaipur jewellery shop's septic tank without safety equipment on Monday to remove sludge for the recovery of gold and silver particles lost during washing, police said. The workers were initially reluctant to undertake the work, but agreed to do it after they were offered extra money, they added.

Gold and silver particles are often lost during washing to remove impurities, separating precious materials from unwanted substances, and preparing them for further processing. They are recovered through methods like sedimentation, filtration, and chemical treatment.

Police said the jewellery shop has a process of directing and recovering gold and silver particles from...