Our Business

Carbonatation and Filtration

Milk of lime (slaked lime) is mixed with the raw melter liquor. Carbon dioxide recovered from our boiler flue gas is bubbled through the mixture. The carbon dioxide reacts with the lime to form chalk which attracts the waxes, gums, resins and other impurities in the liquor at a temperature of 80-85°C.

There are 19 filter presses working in parallel through which the liquor is now filtered. This removes the chalk and about half of the colour, together with virtually all the fine debris and insoluble matter. The resulting pressed liquor is then ready for the next stage, Decolourisation.

Meanwhile, as the cake from the filtration still contains a fair amount of sugar, it is made into a slurry and passed through a second filtration stage to recover this sugar which is then sent back to the melting process. The chalk by-product is used on agricultural land as a soil improver.