Removal Of Phosphorus From Magnetite Concentrate By Supersonic-acid Leaching Technique And Mechanism Research

In recent years, there has been an adequate progress in wind power、nuclear andhigh-speed rail field in our country, the quality of materials used are increasingly strictlycontrolled, high-purity pig iron is the indispensable material for producing the high-gradecasting. P, which is the most familiar one and most difficult to be extracted，is harmful tothe quality of high-purity pig iron. There are two kinds of method to produce high-puritypig iron, concentrated method and oxidation method. Chengde city, Hebei province ofChina, where contained vast reserves of magnetite, which was used as the raw material toproduce the high-purity pig iron by using oxidation method. However owing to theoperating complication and high cost, that’s why oxidation method can not be applicationand popularization. So we need to explore a dephosphorization deeply technology withtechnically feasible and economically rational，so as to apply it to the processing of themagnetite.Acid leaching method was selected as the measure of removal phosphorus frommagnetite. Hydrochloric acid, sulfuric acid, nitric acid and citric acid were used to acidleaching test, respectively, hydrochloric acid was determined as the leaching reagent. Thenstudied the optimum technological parameters using hydrochloric acid. The parameterswere described as follows:15%hydrochloric acid dosage, liquid-solid ratio1:1,90.5%of-0.074mm magnetite ions,2hours dephosphorization time,100r/min stirring ratio androom temperature, the dephosphorization ratio could reached95%and the P content ofresidue was lower than0.005%, the loss ratio of total iron was lower than1%. Then theleaching effluent was used to the recycle test, in this process, the P-grade in concentrateincreased with the reuse time.The tentative experiment was performed to verify whether there occurred adsorptionphenomena during the dephosphorization of magnetite concentrate. The maximumphosphate adsorption capacity of the magnetite ions decreased as acid concentrationincreased. The number of–OH groups on the surface of concentrate reduced whenadsorption was conducted in strong acidic solution by the analysis of FT-IR. Except that,the adsorption kinetics and adsorption isotherm were also studied, the adsorption kineticsfollowed pseudo-second-order kinetics equation, Elovich equation and diffusion model,the adsorption experimental data were fitted the Langmuir equation well.The supersonic wave technology was applied to dephosphorization process, theoptimal technological parameters were determined as follows: pre-processing time1h, the time of ultrasound20min,9%hydrochloric acid dosage, ultrasonic power350W,ultrasonic frequency21KHz,81.2%of-0.074mm iron granularity. The leaching effluentwas also used to the recycle test, experimental results indicated that the effluent could berecycled3times by adding4%hydrochloric acid dosage each time.Through the comparison with direct leaching, supersonic leaching was not onlyhelpful to reduce the cost of reagent and grinding, but also helpful to improve theprocessing efficiency, indicating supersonic leaching was an effective method in terms ofmagnetite dephosphorization.