Pflauder kit for precious metals refiner in South Africa

London – Pfaudler is to upgrade mixers for a major refiner of precious metals in South Africa, which is set to significantly increase the capacity of their process reactors.

Working alongside its Robbins & Myers sister company Chemineer, Pfaudler’s process solution is designed to ensure optimum mixing of platinum group metal concentrates, which can severely damage vessels when not set up correctly.

“As platinum group metals are very heavy, the tendency is to run mixers at excessive speeds in order to achieve sufficient solids suspension,” said Pfaudler process engineer Chris Drysdale.

“This not only increases energy bills, but it causes the heavy metal concentrates to damage the glass interior of the tank, which can make the surface increasingly rougher and ultimately lead to chemical attack and failure of the vessel,” he explained.

Using Chemineer’s Maestro software, Pfaudler said it has been able to show its metal refiner customer how efficient top-to-bottom mixing of their tanks will be achieved. Optimum mixing that keeps solids in suspension will also improve productivity by significantly reducing downtime required for cleaning, it noted.

Pfaudler have designed new agitator shafts because the length of the customer’s vessels is not standard. These are dual-flight, but unusually with the same hub size. This allows for a single diameter shaft with two honed areas for the two flights.

The installation also incorporates Pfaudler’s Cryo-Lock system, which utilizes the cryogenic fit between the glass shaft and the glass impeller hub for precise interference fit. The major benefit gained is that impeller changeover can be carried out inside a reactor, rather than having to remove the drive, shaft or access cover.