refined sugar; sugar refining
Refers both to the product (refined sugar) and the process (sugar refining). Context determines which meaning applies.
この工場では精糖を行っています。
This factory carries out sugar refining.
精糖は白く
Refined sugar is white and clean.
sugar refinery; sugar mill
Compound of 精 (refine, purify) and 糖 (sugar). The reading is on'yomi, as expected for a Sino-Japanese compound.