title: Calcium fluoride recovery from fluoride wastewater in a fluidized bed reactor.
abstract: In order to contribute to better resource efficiency and industrial waste management leading to a sustainable production and consumption pattern new processes must be developed, which should be operated in such a way that waste production is reduced or avoided. Fluoride removal by precipitation generates huge amounts of a water rich sludge. Calcium fluoride is not recovered from the waste streams and it is not recycled due to the high water content and the low quality of the sludge. Crystallization process in a fluidized bed reactor (FBR) appears as an alternative technology to the conventional chemical precipitation process. In the crystallization process in a FBR silica sand is usually used as seed material, however silica is a deleterious impurity because it causes losses in the yield of HF and its content should be less than 1%. In this paper, granular calcite has been used as seed material in order to obtain synthetic calcium fluoride. According to the composition (CaF(2)>97%, SiO(2)<1%), the synthetic calcium fluoride from the crystallization process in a FBR is able to be recycled as raw material for the manufacture of hydrofluoric acid leading to a reduction of raw materials consumption. The crystallization process in a FBR to remove fluoride from industrial wastewaters contributes to an environmental friendly production, because it allows to reduce the waste production as well as to increase the recovery of materials.
authors.affiliation: Departamento de Ingeniería Química y Química Inorgánica, Universidad de Cantabria, ETSIIyT, Avda. los Castros s/n, 39005 Santander, Spain. aldacor@unican.es
authors.forename: R
authors.initials: R
authors.lastname: Aldaco
authors.forename: A
authors.initials: A
authors.lastname: Garea
authors.forename: A
authors.initials: A
authors.lastname: Irabien
mesh_terms: D002119:Calcium Carbonate / Q000737:chemistry; D002124:Calcium Fluoride / Q000737:chemistry / Q000302:isolation & purification*; D003460:Crystallization; D005459:Fluorides / Q000302:isolation & purification*; D006858:Hydrofluoric Acid / Q000032:analysis / Q000737:chemistry; D007220:Industrial Waste; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D013997:Time Factors; D014865:Waste Disposal, Fluid; D018508:Water Purification / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D007220:Industrial Waste; D002119:Calcium Carbonate; D002124:Calcium Fluoride; D005459:Fluorides; D006858:Hydrofluoric Acid