▁The ▁calci um ▁ph osph ate ▁particles ▁ent rap ▁some ▁imp ur ities ▁and ▁abs orb ▁others , ▁and ▁then ▁float ▁to ▁the ▁top ▁of ▁the ▁tank , ▁where ▁they ▁can ▁be ▁sk im med ▁off . ▁An ▁alternative ▁to ▁this ▁" ph osph at ation " ▁technique ▁is ▁" car bon at ation ", ▁which ▁is ▁similar , ▁but ▁uses ▁carbon ▁dio x ide ▁and ▁calci um ▁hydro x ide ▁to ▁produce ▁a ▁calci um ▁carbon ate ▁precip itate . ▁ ▁After ▁filtering ▁any ▁remaining ▁sol ids , ▁the ▁clar ified ▁sy rup ▁is ▁de color ized ▁by ▁fil tr ation ▁through ▁activ ated ▁carbon . ▁B one ▁char ▁or ▁coal - based ▁activ ated ▁carbon ▁is ▁tradition ally ▁used ▁in ▁this ▁role . ▁Some ▁remaining ▁color - form ing ▁imp ur ities ▁are ▁ad s or bed ▁by ▁the ▁carbon . ▁The ▁pur ified ▁sy rup ▁is ▁then ▁concentr ated ▁to ▁su pers atur ation ▁and ▁repeatedly ▁cry st all ized ▁in ▁a ▁vac u um , ▁to ▁produce ▁white ▁ref ined ▁sugar . ▁As ▁in ▁a ▁sugar ▁mill , ▁the ▁sugar ▁cry st als ▁are ▁separated ▁from ▁the ▁mol ass es ▁by ▁cent rif ug ing . ▁Add itional ▁sugar ▁is ▁recovered ▁by ▁bl ending ▁the ▁remaining ▁sy rup ▁with ▁the ▁was h ings ▁from ▁aff ination ▁and ▁again ▁cry st all izing ▁to ▁produce ▁brown ▁sugar . ▁When ▁no ▁more ▁sugar ▁can ▁be ▁econom ically ▁recovered , ▁the ▁final ▁mol ass es ▁still ▁contains ▁ 2 0 – 3