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8/11/2019 Inside a Sugar Factory June 2014
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British Sugar 2010
Inside a sugar factory
Learning objective:
To understand the key stages in the production of sugar
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British Sugar 2010
At the sugar factory
The extraction and production of sugar from
sugar beet takes place at factories on a large
scale.
Other products are also produced such as icing
sugar, caster sugar, Demerara sugar, dark and
light brown sugar and syrups. Co-products
from the production of sugar are also produced
including animal feed, soil, stones, tomatoes
and electricity.
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1. Weighing and sampling
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1. Weighing and sampling
A sample from each delivery of sugar beet
entering the factory is weighed and then
tested to determine its sugar content.
On average one hectare of sugar beet crop
yields about 41 tonnes of clean, topped roots
from which seven tonnes of sugar can be
extracted.
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British Sugar 2010
2. Cleaning
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2. Cleaning
In the cleaning stage of the process the
sugar beet is washed in large quantities
of water, allowing it to pass through weed
and stone separators, before being
separated from the water by a vibrating
screen, known as a dewatering screen.
The sugar beet flows through the
separators by the force of gravity.
The co-products of this process are
topsoil and stones, which are removed for
separate processing at this stage.
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3. Slicing and diffusion
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3. Slicing and diffusion
The slicers slice up to 520 tonnes of sugar beet
an hour and work in a similar manner to a
kitchen grater. They cut the sugar beet into
thinvshaped strips called cossettes.
These are then pumped into three diffusion
towers where they are mixed with hot water to
extract the sugar.
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3. Slicing & diffusion
The water temperature in the diffusers is about 70C; a little cooler than water
from a household kettle.
The sugar passes from the plant cells into the surrounding water.
From this process two important substances remain the pulp and the sugar
that is in the water, which is known as raw juice.
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What happens to the pulp?
The pulp is mechanically pressed to extract as
much remaining sugar and water as possible.
Molasses is added, before it is dried at 880
C(about nine times hotter than a household kettle)
before being formed into pellets.
The pellets are sold in bulk as animal feed for
cattle, sheep, horses and other livestock.
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4. Purification
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4. Purification
The raw juice from the diffusion process passes through an important
purification stage called carbonatation.
Milk of lime (calcium hydroxide) and CO2(carbon dioxide) gas are added.
During this process, the CO2and milk of lime re-combine to produce calcium
carbonatewhich precipitates out, taking most of the impurities with it.
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What happens to the lime?
The solid waste is removed through a filtration
system which uses a series of frame/plate presses
with fine grade cloth filters.
Pressure is applied, which squeezes out the juice,leaving lime solids, trapped by the cloth.
This lime contains trace elements such as v
potassium and magnesium, which is then sold to
farmers as a soil improving fertiliser.
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5. Evaporation
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6. Crystallisation
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6. Crystallisation
The thickjuiceis placed in pans which boil the
juice under pressure (vacuum), to lower the
boiling point.
The thickjuiceis seededwith tiny sugar crystals
which provide the nucleus for larger crystals togrow.
A solution which is about to crystallise is known
as super saturated.
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6. Crystallisation
Once the crystals have reached the desired
size, the process is stopped. The resultant
mixture of crystal sugar and syrup, known as
massecuite, is spun in centrifuges to separate
the sugar from the mother liquor. Once the
sugar crystals have been removed the
remaining juice is returned to the process to be
spun again.
The sugar crystals are washed, and after
drying and cooling, are conveyed to storage
silos at a rate of 1,200 tonnes on an average
day.
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7. Packaging
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7. Packaging
The sugar that is produced in the factory is sent to
the packaging complex where it is packed via a
series of automated machinery.
A machine automatically channels and measures
the amount of bags going through and pulls them
onto a pallet. Once on pallets, the bags of sugar
are shrink wrapped to protect them from moisture.
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Summary
The stages of sugar production include:
Weighing and sampling
Cleaning
Slicing and diffusion
Purification
Evaporation
Crystallisation
Packaging