鞍山某含菱铁矿强磁精矿流态化磁化焙烧——弱磁选试验研究

Study on Fluidized Magnetic Roasting and Low Magnetic Separation Test of a High Magnetic Concentrate Containing Siderite in Anshan

鞍山某强磁精矿中菱铁矿含量较高,难以实现有效分选。为此,采用流态化焙烧反应器,在传统还原磁化焙烧的基础上,开展了低温预氧化—超低温还原磁化焙烧—弱磁选试验研究。结果表明:①试样TFe品位为29.47%,主要脉石成分SiO_(2)含量为52.81%,有害杂质S、P含量较低;铁主要以赤铁矿的形式存在,分布率为79.37%,其次为碳酸铁11.71%、磁性铁3.46%。②在500℃和550℃的条件下,以工业发生炉煤气为还原气,直接还原磁化焙烧过程中生成弱磁性浮氏体,难以实现弱磁选铁矿物相的完全磁性转化。③采用低温预氧化—超低温还原磁化焙烧可获得稳定的完全强磁性转化,适宜的流态化磁化焙烧参数为550℃预氧化2.5 min,再450℃还原焙烧10 min。④焙烧矿在磨矿细度为-30μm占92.60%、磁场强度为79.60 kA/m的条件下,可获得精矿全铁品位大于63%、全铁回收率大于84%的良好指标。⑤产品XRD分析、BSE矿相检测、EDS能谱检测结果显示试验过程中未见弱磁性赤褐铁矿和浮氏体存在,预氧化矿保持了原试样中含铁物相边界的初始形态,菱铁矿矿物相中类质同象替换的Mg、Ca元素在焙烧过程也未发生迁移,磨矿和弱磁选过程也无法将其分离。

The contents of siderite in a high magnetic concentrate in Anshan is high,so it is difficult to achieve effective separation.Therefore,the fluidized roasting reactor was used to carry out the experimental study of low temperature preoxidation,ultra-low temperature reduction magnetization roasting and low magnetic separation on the basis of traditional reduction magnetization roasting.The results showed that:①The TFe grade of the sample is 29.47%,the contents of the main gangue component SiO_(2) is 52.81%,and the contents of harmful impurities S and P are low.Iron mainly exists in the form of hematite with a distribution rate of 79.37%,followed by iron carbonate of 11.71%and magnetic iron of 3.46%.②Under the conditions of 500℃and 550℃,weakly magnetic wustite is formed in the process of direct reduction magnetization roasting with industrial producer gas as reducing gas.It is difficult to achieve complete magnetic transformation of iron mineral phase.③Stable and complete strong magnetic transformation could be obtained by low temperature pre-oxidation and ultra-low temperature reduction magnetization roasting.The appropriate parameters of fluidized magnetization roasting are pre-oxidation at 550℃for 2.5 min and reduction roasting at 450℃for 10 min.④Under the conditions of grinding fineness of-30μm accounting for 92.60%and magnetic field intensity of 79.60 kA/m,a good index of iron concentrate with grade of more than 63%and recovery rate of more than 84%was obtained.⑤The results of XRD analysis,BSE mineral phase detection and EDS detection for the productions showed that there was no weakly magnetic hematite and wustite in the test process,the pre-oxidized ore maintained the initial shape of the phase boundary of the iron-bearing material in the original sample,and Mg and Ca elements in the siderite mineral phase through isomorphism did not migrate during the roasting process,also the process of grinding and low intensity magnetic separation couldn't achieve separation.