铁矿烧结烟气污染物协同控制与高值转化基础研究

As one of the important economic bases and also one of the heavy pollution resources, iron and steel industry emitted huge amount of the dust/smoke and SO2 every year and shared about 10% of the dust/smoke and 6% of SO2 in China. And the half of them is produced in the sintering process of the iron ores. The poluttants of the sintering flue gas are just controlled primarily and needed to be enhanced. With the aim of dereasing the pollutant emission and increasing the economic efficiency, the joint control and the effective utilization of the pollutants are suggested in this project. The production and the interaction of the typical flue gas pollutants as the smoke/dust, SO2, NOx, heavy metals and dioxin will be studied by the local detection in factory and the simulation in the laboratory. The pollutants will be joint controled and reduced by the part recycling of the flue gas and the seperative treatment of the raw materials. Based on the knowledges of the solution, crystallization, structure and molecular simulation, the technologies and the mechanisms involved in the formation of calcium sulfate whiskers from the desulfurization gypsum will studied in detail, including the effective removal of the impurities as Si,Ca, and heavy metals, the one-dimensional growth of the calcium sulfate whiskers, the manufacture of the plastic composite and the clean papers. The present work is expected to provide some basic data and the alternative technologies for the clean sintering of the iron ores.

钢铁工业是我国国民经济重要的基础产业，但也是重污染行业，烟粉尘和SO2排放量已占全国工业总排放量的10%和6%，其中一半以上来自铁矿烧结。烧结烟气污染物排放量大且种类繁多，至今处于粗放管理状态，缺乏系统监控研究。本项目提出采用协同控制与高值转化新思路治理烧结烟气污染物，旨在促进减排增效。首先通过现场监测与实验室模拟研究相结合方式，查明典型烟气污染物（烟尘/SO2/NOx/重金属/二噁英等）产生途径和相互作用机制，探讨通过部分烟气前端循环、物料分级处理等措施实现污染物协同控制与减排的可能性与过程规律；然后以钙法脱硫石膏高值利用为突破口，综合利用溶液/结晶/结构/分子模拟等知识以及各种现代测试手段，系统研究由脱硫石膏制备硫酸钙晶须涉及的硅/钙/重金属等杂质的全面分离、晶须的水热定向生长机制、工程塑料和生态纸品的制备新方法等关键技术和过程机制，为铁矿烧结工序的清洁生产提供基础数据和技术支撑。

采用源头削减和过程控制研究铁矿烧结烟气污染物协同控制。源头削减方面，基于对烧结烟气污染物的“来源”、轨迹和分布规律的研究，确定烧结物料中典型污染元素的比率及对烟气污染物生成的影响程度；提出将含硫量相对较高的铁矿石置于烧结料球内部的制粒新工艺，减少硫与氧的接触，实现SO2减排41%；停止烧结三、四电场除尘灰等高氯物料的内循环，实现二噁英减排40%，同时减少了碱金属等的带入。过程控制方面，通过烧结机风箱中主要烟气污染物排放特征的研究，提出新型三段式烟气循环和SO2、NOx协同减排新工艺，将烧结烟气分为高温低SO2段（循环烟气）、高温高SO2段（脱硫烟气）和低温高NOx段（脱硝烟气）。循环烟气采用前端循环的选择性循环优化方案，回收烧结烟气热量213.9MJ/t-矿；脱硫烟气中SO2浓度富集约3倍；脱硝烟气中NOx浓度富集约1.5倍，利用优化的烧结矿竖式换热装置提升其温度，采用SCR工艺脱硝，烧结矿余热回收提高252.8MJ/t-矿；污染物脱除效率提高的同时增加烧结余热回收。 . 末端方面，针对烧结烟气钙法脱硫石膏主要杂质为未转化的石灰/石灰石、重金属以及硅酸盐，研发出选择性固固分离新技术，通过颗粒高效解离及分级分离，全面、深度脱除重金属及其它杂质，除杂后脱硫石膏纯度大于98%，白度大于90%。以除杂后脱硫石膏为原料，通过低温焙烧及过饱和度调控，实现高活性前驱体快速转化硫酸钙晶须。研究发现与C轴平行的晶面富含SO42-，利用可溶镁盐及阳离子表面活性剂静电吸附诱导晶须选择性生长，实现高长径比（＞500）硫酸钙晶须的水热可控制备。通过邻苯二甲酸二丁酯高增塑，使PVC复合材料中脱硫石膏填充量达70wt%；通过硫酸钙晶须表面富羟基化及多级结构调控，强化晶须与聚合物基体界面相互作用，制备力学性能优良的PVC复合材料。