Magnesium (MgO) in phosphate rock causes numerous problems in the phosphoric acid manufacturing process, including reducing filtration capacity, increasing sulfuric acid consumption, and making it difficult to meet product grade. MgO-containing minerals are fully dissolved and usually coexist in phosphoric acid by acid hydrolysis reaction to form Mg(H2PO4)2. This makes it extremely difficult to separate the dissolved Mg from phosphoric acid. Therefore, it makes both economic and technological sense to remove dolomite from phosphate prior to acidulation. Except for limited use of heavy media gravity separation, flotation is the main technology currently practiced for separation of dolomite from phosphate. Because fine grinding is required to liberate dolomite for flotation separation, use of mechanical flotation cells is very expensive due to energy cost, long flotation time and high reagent use.
Recent development efforts have resulted in industry acceptance of an innovative flotation device, the packed flotation column (PFC), thus realizing its six (6) main advantages: low energy use long separation zone small footprint reduced water use high throughput effective for very fine particles
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