Barium recovery by crystallization in a fluidized-bed reactor: Effects of pH, Ba/P molar ratio and seed

The effects of process conditions, including upward velocity inside the column, the amount of added seed and seed size, the pH value of the precipitant or the phosphate stream and the Ba/P molar ratio in a fluidized-bed reactor (FBR) were studied with a view to producing BaHPO4 crystals of significant size and maximize the removal of barium. XRD were used to identify the products that were collected from the FBR Experimental results show that an upward velocity of 48 cm min(-1) produced the largest BaHPO4 crystals with a size of around 0.84-1.0 mm. The addition of seed crystals has no effect on barium removal. The use of a seed of a size in the ranges unseeded < 0.149-0.29 mm < 0.149 mm < 0.29-0.42 mm produced increasing amounts of increasingly large crystals. The largest BaHPO4 crystals were obtained at pH 8.4-8.8 with a Ba/P molar ratio of 1.0. In the homogeneous and heterogeneous processes, around 98% of barium was removed at pH 8.4-8.6 and [Ba]/[P] = 1.0. The XRD results show that a significant amount of barium phosphate (Ba-3(PO4)(2)) was obtained at pH 11. The compounds BaHPO4 and BaO were present at a pH of below 10. (C) 2014 Elsevier Ltd. All rights reserved.