氢气还原富铁矿石制备零价铁富集磷

Enrichment of phosphate by Zero-valent iron prepared by the hydrogen reduction of iron-rich ore

以褐铁矿、菱铁矿、赤铁矿和磁铁矿为原料,在600℃下氢气焙烧制备零价铁(ZVI)。采用X射线衍射仪、X射线荧光光谱仪、比表面积和孔结构分析仪、扫描电镜、X射线光电子能谱、红外光谱表征了富铁矿石矿物组成及制备产物ZVI的形貌、比表面积和孔结构特征,考察了接触时间、初始磷浓度和pH值对磷富集的影响,并分析了pH值为3和5时,富铁矿石中Pb(Ⅱ)、Cu(Ⅱ)、Hg(Ⅱ)的释放情况,探讨了零价铁对磷的富集性能及作用机制。结果表明,磁铁矿制备的ZVI中铁含量较高(Fe_(2)O_(3) 87.4%)、杂质较少、拥有大量的微纳米孔隙且矿石原样在15天内未检出Pb(Ⅱ)、Cu(Ⅱ)、Hg(Ⅱ)的释放,磁铁矿制备的ZVI表现出最好的磷富集效果,w(P)可达13.45 mg/g。使用NaOH(2.2 mol/L)溶液可以回收ZVI富集的磷,回收率可达到99.9%。表面络合、静电吸附和Fe氧化产生的Fe(Ⅱ)/Fe(Ⅲ)对磷的共沉淀作用是ZVI富集磷的主要机制。研究结果有助于推动富铁矿石的综合利用及其在磷的深度处理或磷资源循环利用方面的应用。

Natural limonite, siderite, hematite, and magnetite were used as raw materials to prepare zero-valent iron(ZVI) by the hydrogen reduction roasting at 600 ℃. In this paper, with the application of X-ray diffractometer(XRD), X-ray fluorescence spectrometer(XRF), specific surface area and pore structure analyzer, scanning electron microscopy(SEM), X-ray photoelectron spectroscopy(XPS), and Fourier Transform infrared spectroscopy(FTIR), we have studied characteristics of mineral component of iron-rich ore and morphology, specific surface area and pore structure of the prepared product of the ZVI, investigated influences of contact time, initial phosphorous concentration, and pH value on the phosphorous enrichment, analyzed the release capacities of Pb(Ⅱ), Cu(Ⅱ), and Hg(Ⅱ) from the iron-rich ore at p H values of 3 and 5, and explored the enrichment properties and mechanism of phosphorus in the ZVI. The results show that the ZVI prepared from magnetite has relatively high content of iron(Fe_(2)O_(3) 87.4%), less impurities, a large number of micro-nano pores, and no detectable Pb(Ⅱ), Cu(Ⅱ), and Hg(Ⅱ) released from raw ore sample within 15 days. Moreover, the ZVI prepared from magnetite also has the best phosphorous enrichment effect, with up to 13.45 mg/g of phosphorous. Phosphorous of the ZVI can be leached out from the ZVI by the 2.2 mol/L NaOH solution for recovery at recovery rate of 99.9%. The surface complexation and electrostatic adsorption of phosphorous, and co-precipitation of phosphorous and Fe(Ⅱ)/Fe(Ⅲ) produced by the Fe oxidation is the main mechanism for enrichment of phosphorous in the ZVI. This research result is helpful to promote the comprehensive utilization of iron-rich ore and its application in the advanced treatment of phosphorous or the recycling of phosphorous resource.