Groningen">Image:20120526 Suikerfabriek Suiker Unie Hoogkerk Groningen NL.jpg|thumb|Sugar refinery in Groningen
, The Netherlands
A sugar refinery is a refinery
which processes _from_[[sugarcane">cane
_or_[[sugar_beet.html" style="text-decoration: none;"class="mw-redirect" title="sugarcane.html" style="text-decoration: none;"class="mw-redirect" title="raw sugar from [[sugarcane">cane or [[sugar beet">beets into [[white refined sugar]].
Many [[cane sugar mill]]s produce raw sugar, which is sugar that still contains [[molasses]], giving it more colour (and impurities) than the white sugar which is normally consumed in households and used as an ingredient in soft drink
s and foods. While cane sugar does not need refining to be palatable, sugar from sugar beet
is almost always refined to remove the strong, usually unwanted, taste of beets from it. The refined sugar produced is more than 99 percent pure sucrose
Many sugar mills only operate during the harvest season, whereas refineries may work the year round. Sugar beet refineries tend to have shorter periods when they process beet than cane refineries, but may store intermediate product and process it in the off-season. Raw sugar is either processed and sold locally, or is exported and refined elsewhere.
Sugar refineries date back to Arab Egypt
in the 12th century.
An artisanal version is the trapiche
, later substituted by the engenho
Sugar refineries are often located in heavy sugar-consuming regions such as North America
, and Japan
. Since the 1990s, many state-of-the art sugar refineries have been built in the Middle East and North Africa
region, e.g. in Dubai
, Saudi Arabia
. The world´s largest sugar refinery company is American Sugar Refining
with facilities in North America and Europe.
Raw sugar processing
The raw sugar is stored in large warehouses and then transported into the sugar refinery by means of transport belts. In the traditional refining process, the raw sugar is first mixed with heavy syrup and centrifuge
d to wash away the outer coating of the raw sugar crystals, which is less pure than the crystal interior. Many sugar refineries today buy high pol sugar and can do without the affination process.
The remaining sugar is then dissolved to make a syrup (about 70 percent by weight solids), which is clarified by the addition of phosphoric acid
and calcium hydroxide
that combine to precipitate calcium phosphate
. The calcium phosphate particles entrap some impurities and absorb others, and then float to the top of the tank, where they are skimmed off.
After any remaining solids are filtered out, the clarified syrup is decolorized by filtration through the use of bone char
, which is made from the bones of cattle, a bed of activated carbon
or, in more modern plants, ion-exchange resin
The purified syrup is then concentrated to supersaturation and repeatedly crystallized under vacuum to produce white refined sugar
. As in a sugar mill, the sugar crystals are separated from the mother liquor
by centrifuging. To produce granulated sugar
, in which the individual sugar grains do not clump together, sugar must be dried.
Sugar drying and storage
Drying is accomplished first by drying the sugar in a hot rotary dryer, and then by blowing cool air through it for several days in conditioning silos. The finished product is stored in large concrete or steel silos. It is shipped in bulk, big bag
s or 25 – 50 kg bags to industrial customers or packed in consumer-size packages to retailer
The dried sugar must be handled with caution, as sugar dust explosion
s are possible. For example, a sugar dust explosion which led to 13 fatalities was the 2008 Georgia sugar refinery explosion
in Port Wentworth
Factory automation in sugar refineries
As in many other industries factory automation
has been promoted heavily in sugar refineries in recent decades. The production process is generally controlled by a central process control system
, which directly controls most of the machines and components. Only for certain special machines such as the centrifuges in the sugar house decentralized PLC
s are used for security reasons.
Sugar related online glossary.Centrifugal control and the quality of white sugar by Barbara Rogé et. al., retrieved on 27 June, 2010.