镍铬不锈钢酸洗污泥资源化利用中硫与氟的迁移基础研究

In order to realize the harmless resource utilization of stainless steel pickling sludge, we proposed that the pickling sludge can be used as the metallurgical auxiliary materials after necesary pretreatment. The valuable elements such as nickel, chromium and iron will be recovered within the steelmaking enterprise by a closed loop. But the sludge contains more sulfate and calcium fluoride, the removal efficiency of sulphur and transformation mechanism of sulfate and calcium fluoride in the smelting process are the key problems that need to be resolved ..Research contents of the project: the existed states of sulfur and fluorine in pickling sludge for different wastewater treatment technology; the key control factors and its impact on transformation of sulfur and fluorine in different metallurgical slag and melts；the transformation thermodynamics and dynamics of sulfate and calcium fluoride under coupled effects of multi-factors in roasting, smelting and refining process; the implementing scheme, the effects, the recovery of elements, the impact on the normal smelting and refining process when pickliing sludge used as auxiliary material..Research objects of the project: Proposing the weighting exponent of key factors influencing the transformation of sulfur and fluorine; Constructing equilibrium and nonequilibrium thermodynamics of sulfur and fluorine transformation and migration; Revealing the phase distribution, the forms of existence, the transformation mechanism of sulfur and fluoride among the gas - melt- slag in pretreatment and smelting process; Determining the migration path of sulfur and its removal mechanism between the molten metal and molten slag; Establishing the kinetics models of sulphur and fluorine in comprehensive utilization; Deducing equilibrium distribution model of sulfur between steel and slag; Evaluating the effects of pickliing sludge used as auxiliary material..The research achievements will provide basis for the comprehensive utilization of pickling sludge and other chromium-containing solid wastes.

为资源化利用镍铬不锈钢酸洗污泥，课题提出将有价元素的回收与含铬、氟、硫的固废脱毒，以及熔剂组分的综合利用相结合，作为冶金辅料闭路循环利用的思路。着重解决污泥中硫酸盐及氟化物在冶金熔渣熔体中的转化及迁移问题。研究不同酸洗废水处理方法所产污泥中硫与氟的赋存形态及可控性；冶金熔渣熔体中各种因素对硫氟转化的影响指数；污泥预处理及熔炼过程中多因素耦合作用下硫与氟的转化热、动力学；污泥中元素的回收及可控性、终渣毒性、环境影响等相关问题。建立影响硫、氟转化的关键因素权重指数图；构建硫、氟转化及迁移平衡态及非平衡态热力学；揭示硫氟在预处理及冶炼中在炉气-金属液-熔渣中的分布规律、存在形态、转化机制；确定硫在金属-熔渣中的迁移路径及其脱除的影响机制；探索污泥中硫及氟的解离产物的迁移和释放速率，建立脱硫动力学模型；探明硫、氟界面反应行为、平衡分配模型。为酸洗污泥作为辅料在不锈钢企业闭路循环和减排提供理论依据。

不锈钢酸洗污泥中有价金属Fe、Cr、Ni含量高，并含有一定量的CaF2和CaO，生成率约为不锈钢产量的2.5%-3.0%，是有毒固废也是重要的二次资源。基于将酸洗污泥中有价元素的回收利用与含铬、氟的固体废弃物脱毒、以及熔剂成分的综合利用相结合，在冶金企业闭路循环的利用思路，系统研究了不同品种不锈钢，在不同废水处理参数条件下所得不锈钢酸洗污泥的特征及物化性能；基于酸洗污泥用作烧结原料、电炉渣料和氩氧精炼炉渣料，研究了酸洗污泥作为烧结配料的基础特性及烧结平衡相特性，作为电炉造渣料的热力学及硫含量变化，用作氩氧精炼炉渣料时的钢水硫含量变化，不同时期加入时对钢水质量的影响；不锈钢酸洗污泥脱硫预处理热力学、动力学、污泥脱硫机理，以及污泥配加高炉除尘灰脱硫的效果等。研究表明，高硫酸洗污泥经1000℃下配碳预处理脱硫，脱硫率可达91.62%，脱硫契合度最高的机理函数为Avrami-Erofeev，机理为随机成核和随后生长模型。高硫酸洗污泥与布袋除尘灰比例为8:2，1200℃焙烧3.5h，脱硫率达75.07%，Fe、Cr、Ni回收率分别为91.24%、70.68%及67.11%。作为烧结配料，酸洗污泥配加比例为5%-10%、碱度1.5-2.0时，有利于降低铁矿粉液相开始生成温度；低硫酸洗污泥直接、高硫酸洗污泥脱硫率后，作为电炉渣料和氩氧精炼炉渣料可行。通过研究，阐明了污泥中硫与氟的赋存形态及可控性，明确了硫酸盐及氟化物在冶金熔渣熔体中的转化及迁移规律，各因素对硫酸盐转化的影响，预处理及熔炼过程中硫的转化热、动力学，元素的回收及可控性等问题，建立了脱硫动力学模型，为酸洗污泥作为辅料在不锈钢企业闭路循环和减排提供理论依据。项目资助发表论文20篇，培养硕士生5名，出版专著1本。