Mining conglomerate Ma’aden has partnered with Alcoa to establish in Saudi Arabia the world’s most efficient vertically integrated aluminium complex.  The sheer scale of the operations motivated the design team to seek new ways to improve production processes.

The oxylate circuit is a case in point. Of  the various compounds  found  in  the  organic  fraction,  the  oxalate  anion  is  the contaminant  which  has  the  most  significant  effect  on  the  quality  and  quantity  of alumina refined from the Bayer Process.   Their removal from the Bayer liquor is important, to improve the quality of the spent liquor, the recyclability of the liquor and as a consequence the quality and quantity of the alumina product.

Conventional rotary drum vacuum filters have typically been used to remove these oxylate impurities that build up over time. For this massive plant, drum filters were overlooked in favour of large plate, high volume membrane chamber filter presses.  The ability to both remove low levels of oxalate and the requirement for effective filter cake washing drove the decision for this design change.

The units are fitted with automated plate shifting and high pressure cloth washing to ensure reliable automated operation.