Surface Magnetization Of Weakly Magnetic Iron Minerals

Weakly magnetic iron minerals is very difficult to gain ideal recovery using traditional treatments to separate the minerals due to fine grain size, big specific surface and weak magnetism, which is a big problem in mineral processing for many years.Routine way to enhance surface magnetism is adding magnetic seeds in slurry, but their preparation is costly, and thire adsorption on specific mineral surfaces is not selective. There two main features for this research: oneis that magnetic particles were synthesized directly in slurry, which offer an efficient way to simplify the seeds the prepartation process; the other one is the so-called 'self-magnetization', namely, the magnetization was realized without adding any contitunet containing iron ions.On the basis of summary and analysis of many interrelated literatures, systematical experiments had been carried out to magnetize three weakly magnetic iron minerals, such as limonite, siderite and hematite, as well as real tailings of iron milling.Magnetic particles were synthesized in the slurry through adding ferruginous chloride and adjusting pH. In experiments many factors such as magnetic induction, molar ratio of Fe²⁺ and Fe³⁺ , dosage of ferric ion, slurry temperature and pH etc. were investigated to obtain best conditions which were molar ratio of Fe²⁺ and Fe³⁺3:1, pH value 10.5, reaction temperature 45℃, stirring for 4 minutes. The selectivity of magnetization between mineral limonite and quartz was improved by adding surfactant sodium oleate, with the dosage 3.3×10^-4mol/L, obtained largest recovery difference 52%On the basis of limonite magnetization experiments, it suggested that without ferric ions and just through adjusting pH value of the slurry, siderite magnetism is enhanced, which is called self-magnetization. Thermodynamic research indicated that Fe²⁺ was dissociated from the surface of siderite in acidic condition and could be oxidized into Fe³⁺ partly. Both ferric ions are necessary conditions to synthesize magnetic particles. Research on factors such as pH value of solution, FeCl₃, FeCl₂, H₂O₂, inflating volume etc. indicated that magnetic particles could be synthesized in siderite slurry. Temperature is a main factor influencing on self-magnetization of siderite. Yield of siderite increasing from 53.8% to 94.6% at 100℃indicated siderite realizing magnetization.The experiments on hematite Self-magnetization were took, and self-magnetization of Fe₂O₃ and FeS₂, Fe₂O₃and FeCO₃ realized just by adjusting pH valueKinetic equation of self-magnetization of siderite is: 1-[1-1.5(ε-0.538)]^1/3=ktIt showed that magnetization reaction were effected by hybrid control, the activation energy is 30.11kJ/mol.The experiments on tailing of MeiShan Iron Mine indicated that fine weak magnetic minerals which contain siderite could be magnetized by itself.