Question

Which chemical process is used to isolate platinum-group metals from silicate-rich feedstock by utilizing chlorine gas?

Accepted Answer

The chemical process used to isolate platinum-group metals (PGMs) from silicate-rich feedstock using chlorine gas is known as chlorination roasting. In this process, the raw material—often a concentrate containing metals trapped within rocky silicate minerals—is heated in the presence of chlorine gas. As the material reaches high temperatures, the chlorine reacts specifically with the precious metals to form volatile metal chlorides, which are gaseous chemical compounds containing metal atoms bonded to chlorine. Think of this like using a selective magnet that only pulls out the precious metals while leaving the heavy rock behind. These metal chloride gases are then carried away from the solid silicate waste and cooled, causing them to deposit as solids that can be easily collected and purified. This technique is particularly effective for silicate-rich feeds because it avoids the need to melt the entire mass of rock, which would be energy-intensive and difficult to manage.

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Which chemical process is used to isolate platinum-group metals from silicate-rich feedstock by utilizing chlorine gas?