Cascade, an alumina feed solution
Fives has developed a proprietary technology suitable to modern high amperage smelter to further reduce Gas Treatment Center (GTC) emissions and to meet the highest regulations at lower cost. The patented Cascade Feed system is designed for reducing HF emissions both in summer and winter seasons by reverting to conventional feed mode during winter.
In existing installations, this solution allows aluminium producers to boost their production without increasing stack emissions.
From 30% to 40% HF emission reduction
Cascade Feed technology
GTC HF emissions increase when gas temperature and enriched alumina fluoride content get higher.
To benefit from the relation between HF emissions versus fluoride content of the scrubbing alumina, Fives’ solution is the rearrangement of the conventional alumina distribution systems into a Cascade Feed system. It consists in:
- Injecting a maximum quantity of fresh reagent in the first scrubber unit of a scrubbing module series installed in parallel, each treating an equivalent quantity of raw gases,
- Then redirecting the overflow material to the next modules in series, until the material flows out of the last module to ultimately be reused as enriched alumina into the electrolysis cells.
In opposition, the conventional alumina feed technology is based on an even fresh alumina distribution among GTC operating modules and equal fluorination levels in each scrubber module. This leads to having approximately the same fluoride concentration at each module: from 1.5% to 2.2% for modern smelters.
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