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ALUMINA LIQUOR CLARIFICATION: FILTER MEDIA CLASSIFICATION AND DEVELOPMENT USING IN-LINE, PILOT SCALE, PORTABLE FILTER TESTING EQUIPMENT

Neate M.

Historically manufacturers of industrial filtration media select candidates of new filter media for further field testing based on physical media specification and laboratory testing. Even though these tests have developed the technical sophistication to measure physical parameters such as fluid flow dynamics and equivalent pore size, ultimate design validation of the candidate filter media has been based on large-scale trials in the customer’s process circuit. This may typically incorporate a full filter vessel trial with the results directly affecting the customer’s product at the time of the trial. These trials are often not easy to schedule or monitor and the time frame of design validation can often be lengthy.

Over the last year Albany International has used a custom built, portable, filter testing unit to test new filter media in the clarification circuits of several Alumina refineries in Australia. The test unit can be connected in-line into the process header and new filter media is tested using ‘live’ liquor without disrupting the customer’s manufacturing process or product.

While full filter vessel trials are a necessary developmental step with any new filter media, the use of the in-line pilot scale test unit has refined and expedited the media selection and design parameters to a significant degree prior to such trials. The traditional multiple large-scale ‘trial’ development has been replaced by small scale, non-intrusive, intermediate-stage testing.

This paper presents the findings of several infield comparative tests, highlighting the operational and variable differences observed utilising the filter testing unit in Alumina refineries in Australia, and illustrates how these findings are utilised in implementing design improvements to filter media.