The carbohydrate sugar is produced by every green plant. In our latitudes the most used source of sugar is sugar beet:

Harvested and topped sugar beet (with the leaves removed) is delivered to the sugar factory where it passes from the beet store to the washing plant and from there to the cutting machine. Hot water is used to dissolve the sugar out of the finely cut sugarbeet chips in large extraction towers (juice extraction department). The result is a cloudy, raw juice (grey to blackish in colour and with a sugar content of between 12 and 14%) containing non-sugar substances such as phosphate, magnesium, protein, citric and malic acids, etc., which are removed in the juice cleaning department using lime, carbon dioxide and filters. What remains is a clear thin juice (light yellow in colour and with a sugar content of between 12 and 14%). This clear thin juice is converted into thick juice (brownish in colour with a sugar content of between 60 and 70 %) in the juice concentration department by means of several stages of water vaporization. In the sugar house or crystallizing department the thick juice is concentrated further still under vacuum in juice boilers (measures are taken to prevent overheating and risk of discoloration). Once this boiling mass exceeds saturation point (solution of sugar in water), the sugar begins to crystallize out.

This mixture of syrup and sugar crystals called the massecuite is cooled in horizontal, round mixer tanks, in which the sugar crystals continue to grow steadily while the mixture is stirred. The sugar crystals are then separated from the syrup in centrifuges, leaving raw sugar (yellowish brown). Adhering residues of the syrup are removed by spraying the raw sugar with water and steam (white sugar). Redissolving the raw sugar crystals thus obtained Produces a clear, pure solution of sugar: the clairce. By repeating the concentration, crystallizing and centrifuging operations, you are finally left with top-quality snow-white sugar, i.e. white refined sugar. Molasses is a side-product of this final crystallizing stage. The sugar contained in the molasses cannot be crystallized out. It is used mainly in the production of yeast, alcohol and feedstuffs (in the latter case the molasses is dried on the extracted sugar pulp). The media needing to be sealed in the sugar production process (raw juice, mixer juice, milk of lime, carbonation juice, thin juice, thick juice, clairce, etc.) are predominantly abrasive with a tendency to crystallize out and form sugar charcoal in the area of the mechanical seal. These characteristics require mechanical seals to display certain special features of design such as e.g. protected positioning of springs, hard face materials, and quenching for single-acting seals. (The tables gives recommendations for the use of mechanical seals in the sugar industry).