菱铁矿微波磁化焙烧磁选工艺及机理研究

Research on Process and Mechanism of Microwave Magnetization Roasting and Magnetic Separation for Siderite

菱铁矿是我国重要的铁矿资源,然而由于其铁品位低、矿物组成复杂,尚未得到大规模开发利用。提出采用微波磁化焙烧技术处理菱铁矿,考察了微波焙烧温度、微波焙烧时间、CO_(2)浓度、磨矿细度以及磁场强度对焙烧产品分选指标的影响规律,同时采用XRD、VSM、SEM-EDS等检测技术分析了微波磁化焙烧过程机理。结果表明:菱铁矿石微波磁化焙烧磁选适宜的工艺参数为焙烧温度650℃、焙烧时间10 min、CO_(2)浓度20%、磨矿细度-0.038 mm占85%、磁选场强136.19 kA/m,此时可获得铁精矿品位61.62%、回收率82.87%的技术指标;随着焙烧反应的进行,弱磁性的菱铁矿石逐渐转变为强磁性磁铁矿,焙烧后样品的磁性显著增强。在焙烧时间10 min时,焙烧产品最大比磁化系数为31.14×10^(-5) m^(3)/kg。焙烧过程中菱铁矿按照由颗粒边缘至内部的空间顺序转变为磁铁矿,且随着反应的进行,裂纹由外向内生成发育。研究结果为菱铁矿资源的高效利用提供了一种新思路。

Siderite is an important iron ore resource in China.However,it has not been developed and utilized on a large scale due to its low grade and complex mineral composition.The microwave magnetic roasting technology was proposed to treat siderite.The effects of microwave roasting temperature,microwave roasting time,CO_(2) concentration,grinding fineness and magnetic field strength on the separation index of calcined products were investigated.At the same time,XRD,VSM,SEM-EDS and other detection techniques were used to analyze the mechanism of microwave magnetic roasting process.The results show that the suitable process parameters for microwave magnetic roasting and magnetic separation of siderite ore are roasting temperature of 650℃,roasting time of 10 min,CO_(2) concentration of 20%,grinding fineness of-0.038 mm of 85%,and magnetic separation field strength of 136.19 kA/m.The technical indexes of iron concentrate grade of 61.62%and recovery rate of 82.87%can be obtained.As the roasting proceeds,the low intensity magnetic siderite gradually transforms into a high intensity magnetic magnetite,and the magnetism of the sample after roasting is significantly enhanced.When the roasting time is 10 min,the maximum specific magnetization coefficient of the roasted product is 31.14×10^(-5) m^(3)/kg.During the roasting process,siderite is transformed into magnetite in the spatial order from the edge of the particles to the inside,and cracks are generated and developed from the outside to the inside as the reaction progresses.The research results provide a new idea for the efficient utilization of siderite resources.