Mechanism of the impact of hydrogen/oxygen bubbles in the separation and hydrogen production of coal macerals electroflotation

doi:10.16085/j.issn.1000-6613.2023-2114

Abstract

Abstract:

Electroflotation technology is an effective way to achieve efficient separation of coal macerals and it is also a hydrogen and oxygen production technology with significant advantages. Electrolytic bubbles in electroflotation are carriers for flotation separation and are also effective hydrogen/oxygen products. This study explored the impact mechanism of electrolytic bubbles on the separation efficiency of macerals in high-inertinite coal electroflotation. Induced timer, infrared spectroscopy, contact angle measurement, and gas chromatography were used to investigate the selectivity of hydrogen and oxygen bubbles for coal macerals, and the impact of electrochemical reaction on coal structure, flotability and gas product composition. The results showed that the yield and vitrinite content of the concentrates obtained by electrolytic hydrogen bubble flotation were higher than those with oxygen bubbles, and the corresponding vitrinite recovery rate was also higher than that with oxygen bubbles. The electrolytic action during the electroflotation process improved the surface structure of coal macerals, causing changes in wettability. The cathode region of electroflotation had an electrochemical reduction effect on coal, which could reduce the hydrophilic functional groups such as —OH, —COOH, and C $̿$ O in coal, thereby increasing the contact angle of coal samples and reducing the induction time of hydrogen bubbles on coal, thus increasing the floatability of coal. And the anode region had the opposite effect. In the electroflotation process of coal slurry, hydrogen gas with a purity of >94% and oxygen gas with a purity of >96% were obtained, and the purity of the gas products using vitrinite as electrolyte was higher than that with inertinite, but the inertinite could achieve a higher gas production rate. The two-stage series process was used for the electroflotation of coal macerals, and it had a maximum comprehensive efficiency of 83.7% for flotation separation. The recovery rate of vitrinite in the concentrates was 86.7%, and the recovery rates of the two sink products were 41.6% and 54.9%, respectively, while the hydrogen production rate reached 6.49mL/(min∙cm²).

Key words: coal macerals, electroflotation, electrolytic bubbles, interaction mechanism, hydrogen yield

摘要：

电浮选技术是实现煤岩显微组分高效分离的有效途径，也是一种有显著优势的制氢技术。电浮选中电解气泡既是浮选分离的载体，又是有效的氢气/氧气产物。本文探讨了高惰质组煤电浮选过程中电解气泡对煤岩显微组分分离效果的影响机制，利用诱导时间测定仪、红外光谱、接触角测量仪及气相色谱等考察了氢气泡和氧气泡对煤岩显微组分的选择性以及电化学反应对煤结构和可浮性的影响规律和气体产物组成等。结果表明，电解氢气泡浮选所得的浮物收率及浮物镜质组含量较氧气泡高，相应的镜质组回收率也高于氧气泡；电浮选过程中的电解作用会改善煤岩显微组分的表面结构，引起润湿性的变化，电浮选阴极区对煤具有电化学还原作用，可减少煤中—OH、—COOH与C $̿$ O等亲水性官能团，从而增加煤样的接触角，减小氢气泡对煤的诱导时间，从而增加煤的可浮性，而阳极区的作用相反；煤浆电浮选过程中可获得纯度>94%的氢气和>96%的氧气，且镜质组为电解质时的气体产物纯度高于惰质组，但惰质组可获得更高的产气速率；采用两级串联流程进行煤岩显微组分的电浮选分离时，浮选分离的综合效率最高可达到83.7%，此时浮物的镜质组回收率为86.7%，两个沉物产品的回收率分别为41.6%和54.9%，氢气的产率可达到6.49mL/(min∙cm²)。

关键词: 煤岩显微组分, 电浮选, 电解气泡, 作用机制, 氢气产率

CLC Number:

TQ536

ZHAO Wei, JIANG Yuhan, LI Zhen, LI Yihong, ZHOU Anning, WANG Hong. Mechanism of the impact of hydrogen/oxygen bubbles in the separation and hydrogen production of coal macerals electroflotation[J]. Chemical Industry and Engineering Progress, 2024, 43(5): 2428-2435.

赵伟, 江雨寒, 李振, 李毅红, 周安宁, 王宏. 煤岩显微组分电浮选分离与制氢过程中氢/氧气泡的影响机制[J]. 化工进展, 2024, 43(5): 2428-2435.

Figures/Tables 9

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煤样	工业分析（质量分数）/%				元素分析（质量分数）/%					显微组分组成
煤样	M_ad	A_d	V_daf	FC_daf	C_daf	H_daf	O_daf	N_daf	S_t,ad	镜质组（质量分数）/%	惰质组（质量分数）/%	壳质组（质量分数）/%	矿物质（质量分数）/%	镜质组反射率/%
SFR	5.7	3.9	33.1	63.6	74.9	4.9	14.2	1.3	0.2	56.2	40.1	1.1	2.6	0.638
SFV	5.8	4.1	42.8	54.1	73.8	5.5	14.4	1.6	0.2	95.4	2.4	1.2	1.0	—
SFI	5.1	4.5	30.8	65.9	82.5	4.1	13.4	1.1	0.4	3.1	93.4	0.6	2.9	—

煤样	工业分析（质量分数）/%				元素分析（质量分数）/%					显微组分组成
煤样	M_ad	A_d	V_daf	FC_daf	C_daf	H_daf	O_daf	N_daf	S_t,ad	镜质组（质量分数）/%	惰质组（质量分数）/%	壳质组（质量分数）/%	矿物质（质量分数）/%	镜质组反射率/%
SFR	5.7	3.9	33.1	63.6	74.9	4.9	14.2	1.3	0.2	56.2	40.1	1.1	2.6	0.638
SFV	5.8	4.1	42.8	54.1	73.8	5.5	14.4	1.6	0.2	95.4	2.4	1.2	1.0	—
SFI	5.1	4.5	30.8	65.9	82.5	4.1	13.4	1.1	0.4	3.1	93.4	0.6	2.9	—

气泡类型	电解时间 /min	γ_浮（质量分数）/%	β_浮·V（质量分数）/%	ε_V/%
氧气泡	4	34.2	84.8	49.41
	6	36.8	84.4	52.91
	8	39.7	83.4	56.41
	10	40.3	80.5	55.27
	12	41.1	78.4	54.89
	14	41.7	75.5	53.63
	16	42.1	73.5	52.71
	18	42.3	71.6	51.60
	20	42.6	68.6	49.78
氢气泡	4	33.2	93.8	53.05
	6	45.4	92.7	71.70
	8	49.5	91.4	77.08
	10	50.1	89.4	76.30
	12	52.2	86.5	76.92
	14	52.9	83.9	75.61
	16	53.1	84.1	76.08
	18	54.1	83.4	76.86
	20	54.6	83.8	77.95

气泡类型	电解时间 /min	γ_浮（质量分数）/%	β_浮·V（质量分数）/%	ε_V/%
氧气泡	4	34.2	84.8	49.41
	6	36.8	84.4	52.91
	8	39.7	83.4	56.41
	10	40.3	80.5	55.27
	12	41.1	78.4	54.89
	14	41.7	75.5	53.63
	16	42.1	73.5	52.71
	18	42.3	71.6	51.60
	20	42.6	68.6	49.78
氢气泡	4	33.2	93.8	53.05
	6	45.4	92.7	71.70
	8	49.5	91.4	77.08
	10	50.1	89.4	76.30
	12	52.2	86.5	76.92
	14	52.9	83.9	75.61
	16	53.1	84.1	76.08
	18	54.1	83.4	76.86
	20	54.6	83.8	77.95

溶液体系	气体速率 /mL·min^-1·cm^-2	体积分数/%
溶液体系	气体速率 /mL·min^-1·cm^-2	H₂	O₂	CO	CO₂	CH₄
纯水	2.44	—	100.00	—	—	—
SFI	3.48	—	96.46	0.65	2.89	—
SFV	2.91	—	98.27	0.36	1.25	0. 12