软锰矿干法烟气脱硫基础研究

The SO2 emission in the flue gas from combustion facilities in numerous industrial factories, such as electric power plants, has caused serious environmental damage in our society. The current flue gas desulfurization technologies, including the limestone-gypsum wet method and the pyrolusite pulp desulfurization process, are considered less economically beneficial due to the very limited application of the by-product gypsum and the second water or air pollution in our country. In this project, a new concept for flue gas desulfurization with a dry pyrolusite ore was conceived to control the emission of SO2. It was proposed based on the multi-disciplinary approach consisting of energy engineering, metallurgical engineering and environmental engineering. It is known that MnO2 has a porous structure and a specific oxidizing property while SO2 has a reducing property. The specific phase transformation from MnO2 to MnSO4 will be achieved as the redox reaction takes place between dry pyrolusite and SO2 gas, targeting at integrating both flue gas desulfurization and the specific reduction of pyrolusite into one-step process. Equilibrium diagrams of Me-S-O (Me=Mn,Fe)systems will be constructed based on the thermodynamic study, where the predominant areas of various manganese oxides and sulfates will be figured out and the favorable routine for the transformation from MnO2 to MnSO4 will be discovered. The micro and macro structures as well as the adsorption performance of the pyrolusite ore and the behaviors of the associated iron minerals will be examined by the study on the crystal structure and suface chemistry of pyrolusite ores. The mechanisms on the flue gas desulfurization with pyrolusite and the in-situ specific transformation from MnO2 to MnSO4 will be revealed through the kinetic study. Then effective ways will be found for enhancing the process of flue gas desulfurization. A new technology for flue gas desulfurization with a dry pyrolusite ore will be firstly developed based on the process optimizing tests. Economic value will be found in both the extraction of manganese from pyrolusite ores and the treatment of SO2-containing flue gases from the present investigation. It will make a great sense in the fields of energy,metallurgy and environment.

针对我国火电等行业烟气污染严重，现行脱硫技术存在经济效益低和二次污染严重等不足，将能源、冶金和环境等学科交叉融合，提出软锰矿干法烟气脱硫新思路，借MnO2的多孔结构和氧化性以及SO2的还原性，在MnO2与SO2发生气固氧化还原反应之时，实现MnO2→MnSO4的原位定向转化，一步达到烟气脱硫和软锰矿定向还原两个目的。通过热力学研究，建立Me-S-O系平衡图，查明不同条件下，锰、铁氧化物及其硫酸盐的稳定区，找出MnO2→MnSO4 转化的有利条件；利用软锰矿的晶体结构和表面化学研究，查明锰、铁氧化物的微观与宏观结构特征及其吸附特性；基于软锰矿与SO2 的气固反应动力学研究，查明脱硫反应机理以及MnO2→MnSO4定向转化机制，找出强化脱硫反应的有效措施，并初步开发出软锰矿干法烟气脱硫新技术。本项目以废气提锰，以锰矿治废，实现提锰与治废经济效益双高，对能源、环境及冶金行业具有重要意义。

烟气脱硫是防治大气污染的重要手段。现行工业脱硫技术，如石灰石-石膏法和软锰矿浆法，存在经济效益低和二次污染严重等不足。本项目通过热力学计算，绘制了不同温度下Mn-S-O系热力学平衡图，查明了不同条件下，Mn-S-O系中锰氧化物及其硫酸盐的稳定区，找出了脱硫过程实现MnO2→MnSO4 转化的有利条件，从热力学角度分析了采用天然锰氧化物进行烟气脱硫的可能性。结合天然锰氧化物中氧化铁杂质含量较高的特性，进一步绘制了Mn-S-O系和Fe-S-O系热力学平衡图的叠加图，根据Fe2O3和MnSO4的共存区域，提出了利用天然锰氧化物进行烟气脱硫，使锰选择性还原成硫酸锰的技术路线。采用XRD和SEM/EDX等技术对软锰矿脱硫过程中Mn、Fe、S的行为及其形态转变进行了研究，发现脱硫过程主要发生氧化锰与SO2的硫酸化反应，Fe基本上不与SO2作用，同时证实了软锰矿的多孔特性。利用固定床反应器考察了反应温度、矿石粒度等条件对氧化锰矿脱硫过程的影响，发现温度对脱硫过程影响较大，在300~500°C范围内，脱硫率随着反应温度的提高先是增大而后降低，在400℃时达到最大值；矿石粒度对软锰矿烟气脱硫过程具有一定的影响，粒度过大对脱硫不利。在较宽的温度范围内，利用软锰矿脱硫能够将烟气中的SO2脱除到小于0.5 ppm的水平，脱硫尾气可达到排放要求。.本项目的研究从理论和实践证实了天然软锰矿烟气脱硫并制备硫酸锰的热力学可能性及技术可行性，可为含硫烟气的治理提供一条新的技术路线，同时对天然低品位锰氧化物的资源化高效利用开辟一条新的技术途径，具有较大的潜在应用价值，值得进一步进行深入细致的机理研究。

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