pH Measurements during Carbonatation for Sugar Production

Today, sugar is one of the most important staple foods of mankind. It is also of enormous economic importance:
Sugar is produced in 127 countries. Sugar cane and sugar beets are cultivated on an area of approx. 25 mio hectares worldwide with a sugar production of approx. 120 mio tons. Cane sugar accounts for the major part (2/3) of the sugar produced compared to beet sugar.

The largest sugar-producing countries are:
India (> 12 Mio t), former USSR, Cuba, Brasil, USA, China, France, Australia, Thailand, Mexico, Germany (4 Mio t),
Turkey, Italy, and Poland (2 Mio t).
In Germany the per-capita consumption is approx. 35 kg per year.

Sugar cane and sugar beet contain up to 20 % sugar (chemical: saccharose). Whether sugar cane or sugar beet
serve as source material is only distinguished by different production processes in the beginning, during delivery
and cutting, and by different washing procedures.

The hackled pieces are leached with 70 °C hot water in the so-called diffusion tower. The raw juice produced that way contains almost 99% of the original sugar, however also various organic and inorganic constituents, the so-called non-sugar particles.

The juice is purified using lime and carbonic acid. For that purpose, the sugar plants operate lime kilns where lime stone (calcium carbonate) is heated to produce burnt lime (calcium oxide) and carbon dioxide.

The lime is added to the raw juice as lime milk. In the process, loose calcium hydroxide precipitates are formed which bind the non-sugar particles.

Now, the carbon dioxide is led into this mixture. The lime including the nonsugar particles stably precipitates and can be separated by filtration.

This step is called carbonatation. It is repeated in a second stage.

A clear, light-yellow thin juice with a sugar content of approx. 16% remains, which is further processed for thickening.
The filtrated carbonated lime is used as fertilizer. The sugar is cleaned by solely physical processes (crystalline transformation and centrifugation). In contrast to widespread assumptions, white sugar is not bleached. Brown sugar only contains more syrup (always brown)….

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