Structure composition of coal gasification slag and speciation of main metals in coal gasification slag

doi:10.16085/j.issn.1000-6613.2023-1496

Abstract

Abstract:

The reduction, resource utilization and harmlessness of coal gasification slag are the hotspots of current research in the coal chemical industry. The study of physicochemical properties of coal gasification slag, alongside the content and environmental risk of embedded heavy metals, is the basis to achieve the above purposes. This thesis studied the structure composition and metal speciation of coarse slag and fine slag from a coal chemical industry in Ningdong Base, assessing the environmental risk of main metal elements they contained. The results showed that the coal gasification slag primarily consists of residual carbon and ash, the ash with the main components being SiO₂ (50%) and Al₂O₃ (15%). The coarse slag has a high ash content (>90%) and its particles are dense and smooth, while the fine slag has a high residual carbon content (about 20%) and rich pores. Metals with contents above 500µg/g are mainly enriched in the coarse slag, whereas metals with contents below 200µg/g are enriched in the fine slag. The stability of metals in fine slag is lower than in coarse slag. The proportion of unstable state of Cd in the fine slag is over 70%, and the value of its risk evaluation index is 34.16, which leads to high environmental risk. This study aims to provide basic data for the resourcefulness and harmless treatment of coal gasification slag.

Key words: environment, size distribution, leaching, coal gasification slag, metals, speciation

摘要：

煤气化渣的减量化、资源化和无害化是目前煤化工行业的研究热点，对其物理化学特性及重金属含量与环境风险的研究是实现以上目标的基础。以宁东基地某煤化工生产企业的煤气化渣为研究对象，研究了粗渣和细渣的结构组成及主要金属元素赋存形态与环境风险。结果表明，煤气化渣由残炭和灰分（主要成分为SiO₂和Al₂O₃，质量分数分别为50%和15%左右）组成。粗渣灰分含量高（质量分数>90%）且颗粒致密光滑，细渣残炭含量高（质量分数约20%）且孔隙丰富。含量高于500µg/g的金属元素主要富集在粗渣中，低于200µg/g的金属元素在细渣中富集。细渣中金属元素稳定性较低，特别是Cd，其非稳定态占比高于70%，且风险评价指数为34.16，环境风险高。本研究旨为煤气化渣的资源化和无害化处理提供基础数据。

关键词: 环境, 粒度分布, 浸取, 煤气化渣, 金属, 赋存形态

CLC Number:

TQ536

MA Jing, MA Yulong, ZHU Li, QIAO Song, SUN Yonggang, JI Wenxin. Structure composition of coal gasification slag and speciation of main metals in coal gasification slag[J]. Chemical Industry and Engineering Progress, 2024, 43(10): 5857-5866.

马晶, 马玉龙, 朱莉, 乔松, 孙永刚, 吉文欣. 煤气化渣结构组成及其主要金属元素赋存形态[J]. 化工进展, 2024, 43(10): 5857-5866.

Figures/Tables 16

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步骤	形态	操作方法	反应条件
1	可交换态	1g样品加40mL 1mol/L CH₃COONa	室温振荡16h
2	碳酸盐结合态	步骤1残渣加40mL 0.11mol/L CH₃COOH	室温振荡16h
3	铁锰氧化物态	步骤2残渣加40mL 0.1mol/L NH₂OH·HCl，pH=2	室温振荡16h
4	有机态	①步骤3残渣加10mL 8.8mol/L H₂O₂	室温间歇振荡1h，85℃水浴中1h，加热至溶液剩余2~3mL。重复此步骤一次
4	有机态	②上一步残渣加50mL 1mol/L NH₄Ac，pH=2	室温振荡16h
5	残渣态	HF+HCl+HClO₄+HNO₃	消解至澄清透明

步骤	形态	操作方法	反应条件
1	可交换态	1g样品加40mL 1mol/L CH₃COONa	室温振荡16h
2	碳酸盐结合态	步骤1残渣加40mL 0.11mol/L CH₃COOH	室温振荡16h
3	铁锰氧化物态	步骤2残渣加40mL 0.1mol/L NH₂OH·HCl，pH=2	室温振荡16h
4	有机态	①步骤3残渣加10mL 8.8mol/L H₂O₂	室温间歇振荡1h，85℃水浴中1h，加热至溶液剩余2~3mL。重复此步骤一次
4	有机态	②上一步残渣加50mL 1mol/L NH₄Ac，pH=2	室温振荡16h
5	残渣态	HF+HCl+HClO₄+HNO₃	消解至澄清透明

环境风险等级	RAC
低风险	≤1
中等风险	1~10
较高风险	10~30
高风险	30~50
极高风险	≥50

环境风险等级	RAC
低风险	≤1
中等风险	1~10
较高风险	10~30
高风险	30~50
极高风险	≥50

样品	工业分析			元素分析
样品	M^①	A^②	LOI^③	C	H	N	S
细渣	52.12±5.68	77.72±4.15	22.34±4.50	13.78±9.32	0.25±0.06	0.86±0.62	0.44±0.09
粗渣	8.02±1.33	96.00±3.97	3.35±3.28	4.00±2.72	0.20±0.02	1.00±0.93	0.62±0.10