Ron takes a close look at the tremendous success of the Wissington Sugar factory
When I first came to the area I was, of course, immediately aware that the one feature that dominated the landscape was the sugar factory. I was totally ignorant of the processes involved in extracting sugar from sugar beet and knew little about the crop itself. More recently I decided that I should find out something about it. No doubt most readers are familiar with Wissington and the sugar industry but, for the benefit of those who are as ignorant of the business as I was, I give below some of the information that I have obtained:
Wissington is the largest of the sugar producing factories owned by British Sugar. The statistics are impressive; the most striking aspect of which to me was the contribution the factory makes to the local economy. Sugar beet growers in the area are paid about £76million in an average year and the factory pays almost £1million in business rates. There are150 permanent staff which rises to 330 in the processing season, their salaries probably add another £4million or more that goes into the region.
Other statistics are:
Input 900 lorry/trailer loads of beet a day (that is just over one a minute on a 14 hour day and, of course, an equal number of empty vehicles leaving)) delivering 16,000 tonnes a day during the season, giving 2.4million tonnes a year.
Output Up to 1,500 tonnes of crystal sugar per day, distributed in bulk tankers and in 1 tonne and 25kg bags. In addition there is; - a range of liquid sugars. -- 140,000 tonnes of animal feed a year -- 100,000 tonnes of LimeX70, sold as a soil improver. Thus, in addition to the 900 vehicles/day delivering beet, there is another large number taking away the products.
British Sugar produces more than half the UK sugar requirements, the remainder is met mostly by imports which are mostly of cane sugar. British Sugar supply the retail market under the Silver Spoon brand, one of the UK's leading food brands. They are also among the largest animal feed manufacturers in the country. They have six sugar producing factories, two of which, including Bury St Edmunds, are also packaging plants and one plant at Bardney wholly devoted to packaging. (on the face of it, this separation of production and packaging over fairly large distances would seem to generate a lot of extra road traffic).
The stages involved in producing the sugar are essentially as follows: On arrival, after weighing, samples are taken from each load and tested to determine the amount of soil and tops and the sugar content (sugar content above a certain level results in higher payment to the grower). The beet is then cleaned, (the fact that sugar beet floats in water greatly assists this) and then sliced into thin 'V' shaped slices. These slices are mixed with water at 70oC for a period of time when the sugar content is dissolved into the water by diffusion through the beet, the liquid solution is then drawn off, this liquid is referred to as 'raw juice'. The residual vegetable material is pressed to extract as much remaining juice as possible before being removed, mixed with molasses and dried to produce animal feed. The raw juice is then mixed with milk of lime and carbon dioxide gas passed through the mixture, the CO2 combines with the milk of lime to produce calcium carbonate, which precipitates out taking most of the impurities with it. This process is called carbonatation, the precipitate contains valuable trace elements and is sold off as LimeX, the soil conditioner.
The pale yellow juice that now remains is called thin juice and contains about 16% solids, this is passed into evaporator vessels where the water content is boiled off to produce 'thick juice' which contains about 65% solids. This thick juice is then passed into vacuum pans where the concentration is further increased by boiling at lower temperatures under reduced pressure - at a predetermined concentration the juice is seeded with tiny sugar crystals which provide the nucleus for larger crystals to grow. When they reach the desired size the process is halted, the mixture of sugar crystals and syrup are transferred into a centrifuge where the sugar crystals are separated from the syrup. Surprisingly the sugar crystals are then washed before being dried and stored in the storage silos. The remaining syrup is boiled again at low temperature to produce 'final product sugar' and molasses. Final product sugars are redissolved in the thick juice for reprocessing.
Most of the clouds of water vapour seen billowing out of Wissington arise from the drying process. Some steam is produced for a 30Mw steam turbine used for generating electricity. There is a further 50Mw generating capacity from a gas turbine, giving a total capability of 80Mw. (It would take a forest of at least 100 Swaffham wind turbines to produce the same amount of electricity and even then it would not be sufficient when the wind was not strong enough.). Surplus electricity is supplied to the Nation Grid, up to 50Mw at times.
As we are all now well aware construction of the new ethanol producing plant has started and is expected to be completed within two years. Whether or not this will result in a further input of sugar beet (or other crops?) or whether there will be a reduction in sugar production is not known to me.