危废类生物质煤气化协同利用中砷的释放和迁移转化机理

Researches on the co-utilization of hazardous waste biomass in coal gasification system is of great significance for its efficient resource utilization and disposal. This project intends to carry out studies on the mechanism of release, migration and transformation of arsenic during co-utilization of hazardous waste biomass in coal gasification system. In consideration of the speciation and concentration of arsenic, the distillation residue containing organic arsenide and the wastewater treatment sludge containing inorganic arsenic are chosen as the typical hazardous waste biomass. The gasification and leaching experiments were carried out by using pressurized TG, high temperature tubular furnaces, and isothermal water columns, for simulation of the different conditions on temperature range, pressure intervals and mediums. Firstly, the similarities and differences of the co-utilization of hazardous waste biomass and the gasification of hazardous waste biomass are studied. Secondly, the influence of co-utilization conditions on the release, migration and transformation characteristics of arsenic are studied. Thirdly, the synergistic effect of halogen and sulfur on the release, migration and transformation of arsenic during co-utilization are studied. Finally, the transformation of arsenic in bottom slag to process water during co-utilization of typical hazardous waste biomass are studied, as well as the related mechanism of arsenic solidification, revealing the release, migration and transformation mechanism of arsenic during co-utilization of hazardous waste biomass in coal gasification system. The implementation of this project can provide theoretical support for the co-utilization of hazardous waste biomass in coal gasification system and promote the development of new technologies in hazardous waste biomass utilization.

煤气化协同利用的研究对于危废类生物质的高效资源化利用和无害化处置具有重要意义。本申请拟开展煤气化协同利用危废类生物质中砷的释放和迁移转化机理的研究。对不同砷赋存状态的典型危废类生物质，选取含有机砷化物的蒸馏残渣和含无机砷的废水处理污泥，在不同温度范围、不同压力区间和不同介质条件，分别采用加压热重、高温管式炉和等温水柱开展气化和浸出实验研究，首先，研究危废类生物质协同利用与仅有危废类生物质气化的异同；其次，研究协同利用条件对砷释放和迁移转化特性的影响规律；再次，研究协同利用过程中卤素和硫素对砷释放和迁移转化的协同作用；最后，探讨典型危废类生物质协同利用过程灰渣中砷转化到工艺水的规律，并对砷固化的关联影响机制开展研究，掌握煤气化协同利用时的砷的释放规律以及砷的迁移转化途径和模式。该课题的实施可以为危废类生物质的煤气化协同利用提供理论支持，促进新型危废类生物质利用技术的发展。

在减污降碳、节能降耗和“无废城市”建设背景下，煤化工企业具有利用危废类生物质作为替代原料的潜力和需求。煤气化协同利用技术将在我国危废类生物质资源化利用和无害化处置方面发挥越来越重要的作用。本项目针对煤气化协同利用危废类生物质过程中砷释放规律及砷迁移转化途径和模式的关键科学问题开展了系统性研究。通过开展高温气化和和等温浸出实验及模拟研究，建立了危废类生物质协同利用热分析动力学模型；揭示了危废类生物质协同利用对砷释放、迁移的影响规律；掌握了不同工艺水条件下砷的转化行为，阐述了危废类生物质协同利用对砷固化的关联影响。研究结果表明，水煤浆气化中药渣的协同利用以及水蒸气的存在明显促进了砷的释放，增加了砷的捕集难度，引入氯、硫酸根等离子对砷转化的影响因灰渣特性而异，工艺水氧化还原条件是决定砷释放形态及其相间分布的关键因素。项目成果丰富了煤气化协同利用过程中砷的释放与迁移转化机制，为危废类生物质煤气化协同利用技术重金属的环境风险防控提供了科学依据。