Inside a Sugar Factory June 2014

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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2. Cleaning


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British Sugar 2010

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



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.



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.



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.



4. Purification



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.



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.



5. Evaporation


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6. Crystallisation



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.



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

Inside a Sugar Factory June 2014

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