煤灰化过程中砷/硒/铅的释放及矿物的变化规律

李扬; 鲁子龙; 杨赫; 靳立军; 胡浩权

doi:10.1016/S1872-5813(21)60115-9

煤灰化过程中砷/硒/铅的释放及矿物的变化规律

doi: 10.1016/S1872-5813(21)60115-9

大连理工大学化工学院煤化工研究设计所精细化工国家重点实验室，辽宁大连 116024

基金项目: 国家重点研发计划（2018YFB0605104），国家自然科学基金（21776039）和中央高校基本科研业务费（DUT2018TB0）资助

详细信息

作者简介:
李扬：yli@dlut.edu.cn

通讯作者:
Tel: 0411-84986157，E-mail: hhu@dlut.edu.cn

中图分类号: TQ534.9
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- 被引次数: 0
出版历程
- 收稿日期: 2021-04-08
- 修回日期: 2021-05-10
- 网络出版日期: 2021-06-16
- 刊出日期: 2022-01-25

Release characteristics of arsenic, selenium, lead and transformation of minerals during ashing process of coal

State Key Laboratory of Fine Chemicals, Institute of Coal Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China

Funds: The project was supported by National Key R&D Program of China (2018YFB0605104), National Natural Science Foundation of China (21776039) and the Fundamental Research Funds for the Central Universities (DUT2018TB0)

摘要

摘要: 本研究选用两种煤（白音华褐煤和鄂州煤），研究了煤中重金属砷、硒、铅的赋存形态及其在灰化过程的释放规律，并结合煤中矿物质的变化，研究了灰化条件对矿物质转化的影响。通过外推法从热失重曲线确定了煤样的燃尽温度，以此为基准并结合国标法分别对煤样进行低温和高温灰化，对所制备的灰样采用XRD、XRF、TG-DTG等方法进行表征，分析煤中矿物质在不同灰化温度下的变化特征；采用逐级化学提取法分析煤样中As、Se、Pb的形态及含量，同时利用HNO₃ + HF一步法提取煤样中的重金属，提取液中重金属含量均采用电感耦合等离子体质谱法(ICP-MS) 检测。研究结果表明，白音华煤中重金属主要以硫化物结合态形式存在的As为主，且As的挥发性随温度升高而增大；鄂州煤中重金属主要为硫化物结合态的Pb，其挥发性同样极易随温度变化而改变；煤中Se主要以有机结合态和硫化物结合态形式存在。煤在灰化过程中矿物质发生了一系列的变化：如高岭土逐渐脱羟基变成偏高岭土，最终转变成莫来石；黄铁矿氧化形成赤铁矿；石膏脱水形成硬石膏。灰化过程各重金属的释放率受燃烧温度的影响较大，其硫化物结合态含量越高，释放率随温度升高增加的程度越大。
- 煤 /
- 重金属 /
- 逐级提取 /
- 灰化方法 /
- 矿物质
Abstract: In this paper, two kinds of coal (Baiyinhua lignite and coal using in Ezhou Power Plant) were selected to study the occurrence of heavy metals including arsenic (As), selenium (Se) and lead (Pb) in coal and their release behaviors during the ashing process. The influence of ashing conditions on the mineral conversion was also examined by the combination with the changes of minerals in coal. The burn-out temperature of the coal was determined from the thermal weight loss curve by extrapolation method, and then the coal sample was ashed according to the National Standard Method of China. The obtained ash samples were characterized by XRD, XRF, and TG-DTG to analyze the change characteristics of coal minerals at different ashing temperatures. The content and occurrence of As, Se and Pb in coal samples were extracted by sequential chemical extraction method. The heavy metals in the ash sample were extracted by HNO₃ + HF, and the heavy metal content in the extract was detected by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The results show that the heavy metal in BYH coal is mainly As in the form of sulfide bound state, which leads to the increasing volatility of As with temperature easily. However, the heavy metal in EZ is mainly sulfide-bound Pb, which makes it easy to release with temperature. Se in coal mainly exists in the form of organic bound state and sulfide bound state. During coal ashing, kaolin is gradually dehydroxylated into metakaolin and finally converted into mullite; pyrite is oxidized to form hematite; gypsum is dehydrated to form anhydrite. The release rate of heavy metals is greatly affected by the combustion temperature during the ashing process. High content of heavy metals in the sulfide bound state results in high release rate with increasing the temperature.
- coal /
- heavy metal /
- sequential chemical extraction /
- ashing method /
- mineral

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FIG. 1231. FIG. 1231.

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图 1 煤样逐级提取流程示意图

Figure 1 Sequential chemical extraction procedure of coal

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图 2 BYH中As (a)、Se (b)、Pb (c)含量

Figure 2 Concentrations of As (a), Se (b) and Pb (c) in BYH sample

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图 3 EZ逐级提取As (a)、Se (b)、Pb (c)含量

Figure 3 Concentration of As (a), Se (b) and Pb (c) in EZ sample

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图 4 外推法示意图

Figure 4 Diagram of extrapolation method

(a): BYH; (b): EZ

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图 5 HTA及LTA的XRD谱图

Figure 5 XRD of HTA and LTA of BYH and EZ coals

Δ: Quartz; □: Anhedritite; ◆: Hematite; ♣: Muscovite; ♥: Montmorillonite; ♠: Mullite; ●: Mayenite; ○: Anatase; *: Pyrite; $ \forall $: Calcite; ▽: Illite; ◊: Pyroxene

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图 6 灰样TG-DTG曲线

Figure 6 TG-DTG curves of LTA and HTA samples of two coals

(a): BYH; (b): EZ

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表 1 BYH和EZ工业分析和元素分析

Table 1 Proximate and ultimate analyses of BYH and EZ

Sample	Proximate analysis/%			Ultimate analysis w_daf/%
Sample	M_ad	A_d	V_daf	C	H	N	S	O
BYH	2.23	24.19	45.17	72.22	5.35	0.91	0.98	20.54
EZ	0.34	29.75	24.52	83.01	3.71	1.78	0.77	10.73

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表 2 灰产率及其变化率

Table 2 Ash yields and their change rate

Sample	A_LTA/%	A_HTA/%	ΔA/%
BYH	24.78	23.47	5.58
EZ	30.43	29.93	1.67

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表 3 灰成分分析

Table 3 Analyses of ash components

Sample	Concentration w/%									Mole ratio (M)
Sample	Al₂O₃	SiO₂	Fe₂O₃	SO₃	CaO	MgO	Na₂O	K₂O	TiO₂	M_Ca/S	M_Fe/S
BYH LTA	17.62	62.66	6.12	5.38	3.23	0.73	1.66	1.27	0.93	0.81	1.13
BYH HTA	18.02	63.95	6.34	3.15	3.27	0.73	1.67	1.3	1.02	1.26	1.79
EZ LTA	33.8	52.91	3.27	1.31	3.07	0.81	1.46	1.37	1.24	3.35	2.5
EZ HTA	34.8	52.77	3.27	1.33	3.09	0.68	0.99	1.42	1.2	3.32	2.46

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表 4 灰样As、Se、Pb含量

Table 4 Concentration of As, Se, Pb in ash

Sample	Content w/(μg·g⁻¹)
Sample	As	Se	Pb
BYH LTA	263.57	0.18	37.14
BYH HTA	260.83	0	36.12
EZ LTA	7.47	1.60	298.09
EZ HTA	7.23	0.75	224.36

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表 5 灰样As、Se、Pb释放率

Table 5 Release rate of As, Se and Pb in ash

Heavy metal	EZ BR/%		BYH BR/%
Heavy metal	LTA	HTA	LTA	HTA
As	83	83.3	67.3	69.3
Se	82	91.4	97.7	100
Pb	47	59.4	66	68.7

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