An aluminum smelting facilities producing 165,000 t/a aluminum via electrolysis, 285,000 t/a foundry products and thereby recycling 120,000 t/a aluminum scrap needs to treat 43,000 m3/a wastewater. The wastewater contains high amounts of aluminum (up to 50 mg/L), zinc and other heavy metals e.g.  chromium, copper, cadmium, cobalt and lead.

The current facility includes a multi-stage flocculation at several pH-steps via iron salt and various polymeric flocculants. Not only threshold values for metals were not reached, but relatively high concentrations of fluorides were also measured in downstream.

ColFerroX – Pilot

A pilot test was carried out to ensure the application of ColFerroX iron oxides to removal of metals and fluoride in single step and in inLine mode using a by-pass of the main wastewater stream. ColFerroX iron oxides were mixed with the wastewater. Flocs were readily formed and separated by gravitation from the wastewater within a few minutes.



Data showed that using both single-step and inLine mode systems the threshold values for aluminium and zinc were achieved by applying ColFerrox™ particles. The pH value was set to 7-8 with calcium hydroxide prior to application. The adsorption capacity for zinc was 30 mg Zn/g of Colferrox™ iron oxide particles and for aluminium 140 mg Al/g of Colferrox™ iron oxide particles. Next to aluminium and zinc also other heavy metals present in smaller amount were adsorbed from the wastewater by the Colferrox™ iron oxide particles.
Using ColFerroX products in single-step and inLine mode systems could reduce capital and operating costs.

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