A sugar refinery is a refinery which processes raw sugar from cane or sugar extracted from beets into white refined sugar.
Cane sugar mills traditionally 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 drinks and foods. Raw cane sugar does not need refining to be palatable. It is refined for reasons such as health, color, and the requirement for a pure sugar taste. Raw sugar is stable for transport and can be from mills to locations for processing into white sugar. Cane sugar mills / factories often produce a partially refined product called 'Plantation White' for their local market, but this is inferior to white sugar made by refineries.[1]
Beet sugar factories can also produce raw sugar, but this has an unpleasant taste. There is no separate raw sugar stage to the process; the sugar extract from the beet is, after cleaning, crystallised directly into white sugar.[1]