Efficient Technology On Reverse Flotation Of Low-grade Phosphate Rock With High Magnesium Content In Packed Flotation Column

With the scarcity of high-grade ore resources,China will enter a large-scale development and utilization of low-grade phosphate rock era.Conventional flotation equipment in processing low-grade phosphate rock expose the lengthy process and high flotation costs.Column flotation technology made a difference for short process of low-grade phosphate rock beneficiation technology.The technology can simplify beneficiation processes,reduce floor space and number of flotation devices,and reduce engineering investment management and equipment operation fees,which generating significant economic benefits while improving the level of development and utilization of phosphate resources.The technology is advanced,simplifying beneficiation processes,reducing floor space and number of flotation devices,reducing engineering investment management and equipment operation fees.And it generated significant economic benefits while improving the level of development and utilization of phosphate resources.To date,the column flotation technology was not yet applied to Hubei province for low grade phosphate rock with high magnesium.We studied efficient column flotation equipment and technology fitting low-grade phosphate rock,which was an important issue of technological progress.It was a research of flotation for low grade phosphate rock in Hubei.First,the effects of grinding time,the amount of phosphoric acid and collector dosage on the flotation indexes by flotation machine was studied.The results showed that with the increase of grinding time,the smaller of mineral fineness,concentrate grade and recovery would increase.However,the grinding time was over 14.5min concentrate grade increased lowly and concentrate recoveries decreased.With the increase in the amount of phosphoric acid,both concentrate grade and concentrate recovery risen.When the amount of phosphoric acid was more than 12kg/t,concentrate grade declined.With the collector dosage increased,concentrate grade increased steadily,and concentrate recoveries changes little.While the collector dosage was more than0.6kg/t,concentrate grade increased slightly,then reduced gradually,concentrate recovery rate has fallen markedly.Secondly,we investigated the influence of various factors on gas holdup in collection zone from three aspects,such as the superficial gas flow rate,collector dosage,height to diameter ratio in trapping zone respectively.With the increase of superficial gas flow rate,gas holdup in trapping zone gradually increased,but the increases with the increase of superficial gas flow rate decreases.When gas flow rate was more than 300L/h,curve of holdup gas in trapping zone flattened.The collector at a rate of 240mL/h,the gas holdup in trapping zone could be the optimum value.When the superficial gas flow rate was 300L/h to 350L/h,trapping zone with height to diameter ratio of 8 to 10,the collector at a rate of 240mL/h to 360mL/h,the gas holdup in trapping zone could reach 12.44%.With height to diameter ratio in the range of 6 to 8,gas holdup in the capture area increased rapidly with height todiameter ratio increasing.With height to diameter ratio in the range of 8 to 10,gas holdup in the trapping zone was not substantially variable except superficial gas flow rate of 100L/h.When the ratio of high to diameter was more than 10,gas holdup in the trapping zone decreased slightly.A axial dispersion models in capture area of flotation column filled with an corrugated and packed section could be used,where ? is porosity of corrugated and packed section.The value of ?is taken 0.3 to 1.Thirdly,the impact of grinding time,collector dosage,the amount of phosphoric acid,height to diameter ratio in trapping zone,froth height and other factors on the reverse flotation column indexes was studied.Using a single reverse flotation with flotation column,grinding time of 14.5min(grinding fineness-75?m 89.5%),pulp density of 30%(wt.%),pulp of pH = 4.8(the amount of phosphate 12 k g/t),collector dosage of 0.75 kg/t,height to diameter ratio 11,an apparent gas flow of 300 L/h,concentrate phosphorus grade of 32.83%,phosphorus recovery of 94.56% and grade of MgO of 0.82% was obtained.At the same time,tailings phosphorus grade could reduced to 8.64%.For 72 hours of continuous flotation pilot test,concentrate grade could reach more than 32.0% and content of magnesium decreased to 1.0%,while the tailings phosphorus grade reduced to 7.0% or even less.These process indicators meet the requirements of industrial production of phosphoric acid.It was possible to achieve industrialization for high magnesium and low-grade phosphate by a single reverse flotation using flotation column.