Precipitation of boron from waste water of Kirka borax plant

Kirka Boron Inc., which is the largest boron processing plant in Turkey, produces tincal from the run of mine ore and sodium penta borax in the same complex. However, the deficiency of the tailings ponds causes significant problems, since approximately 75 % of the current pond volume is filled with waste water, which consists 3 g/L boron. The boron content of this water should be decreased for its usage in the plant again, meanwhile about concentration of 3 g/L boron creates an environmental risk. In this study, the boron in the effluents of the Kirka Boron Inc. was precipitated using Ca(OH)2 and Al2SO4. The effects of several parameters such as Ca(OH)2 dosage, initial pH, agitation duration, and settling duration were investigated. It was found that, the precipitation was strongly related to the Ca2+ concentration. Therefore, when the initial pH was proceeded towards acidic values, boron precipitation was increased. In conclusion, 97 % of the boron could be precipitated from the solution by two stages and a precipitate assaying 38 % B2O3 was obtained.