METHOD FOR RECYCLING AND REMOVING ORTHOPHOSPHATES USING SLAG AND APPARATUS THEREFOR

摘要

PURPOSE: A method for recycling and removing orthophosphates using slag produced as by-product in steelmaking industries. Generally, slag contains free lime and much CaO, and releases high concentration calcium in water. Therefore, crystallization of Ca5OH(PO4)3 is occurred by reaction of calcium eluted from slag and orthophosphates of wastewater. Crystallized Ca5OH(PO4)3 is discharged, and raw slag is injected into the apparatus for removing orthophosphates by Ca5OH(PO4)3 crystallization. Consequently, orthophosphates are removed and recycled in the form of Ca5OH(PO4)3 crystal. CONSTITUTION: The apparatus for Ca5OH(PO4)3 crystallization includes: primary and secondary pathway(18)(19) installed in the middle of the apparatus; a plate(11) for partitioning the apparatus into lower reaction part and upper settling part; and baffles(17) for better mixing of slag and wastewater. Slag(12) is settled by gravity in primary and secondary pathway(18)(19). In the settling part, micro suspended solids are settled by gravity. Diameter of used slag is 0.075-0.15 mm by screening at sieve of No.200.