脂肪酸不飽和度對低階煤浮選強化的影響機制

徐夢迪; 何琳; 司偉汗; 包西程; 劉曉康; 邢耀文; 桂夏輝; 曹亦俊

doi:10.13374/j.issn2095-9389.2021.10.26.001

脂肪酸不飽和度對低階煤浮選強化的影響機制

doi: 10.13374/j.issn2095-9389.2021.10.26.001

徐夢迪^1, ,,
何琳²,
司偉汗²,
包西程²,
劉曉康²,
邢耀文^1, ,,
桂夏輝¹,
曹亦俊^{1, 3}

1.
中國礦業大學國家煤加工與潔凈化工程技術研究中心，徐州 221116
2.
中國礦業大學化工學院，徐州 221116
3.
鄭州大學河南資源與材料產業河南省協同創新中心，鄭州 450000

基金項目: 國家自然科學基金資助項目（52104277）；江蘇省自然科學基金資助項目（BK20210500）

詳細信息

通訊作者:
徐夢迪, E-mail: cumtxmd@outlook.com

邢耀文, E-mail: cumtxyw@126.com

中圖分類號: TD923
計量
- 文章訪問數: 547
- HTML全文瀏覽量: 225
- PDF下載量: 62
- 被引次數: 0
出版歷程
- 收稿日期: 2021-10-26
- 網絡出版日期: 2021-12-18
- 刊出日期: 2023-02-01

Influence mechanism of fatty acid unsaturation on the intensification of low-rank coal flotation

1.
Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, China
2.
School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, China
3.
Institute of Resources and Materials, Zhengzhou University, Zhengzhou 450000, China

More Information

Corresponding author: XU Meng-di, E-mail: cumtxmd@outlook.com; XING Yao-wen, E-mail: cumtxyw@126.com

摘要

摘要: 為研究脂肪酸不飽和度對低階煤浮選的影響，選擇碳原子個數相同但雙鍵個數依次增加的油酸、亞油酸和亞麻酸作為浮選捕收劑對低階煤進行浮選，并與非極性捕收劑柴油進行對比，通過顆粒–氣泡間粘附力測試和藥劑吸附的分子動力學模擬，揭示了不飽和脂肪酸強化低階煤浮選的作用機制。結果表明，不飽和脂肪酸的浮選性能優于柴油，低階煤浮選產率隨脂肪酸不飽和度增加而增加。采用掃描電鏡（SEM）、傅里葉變換紅外光譜（FTIR）和X射線光電子能譜（XPS）對低階煤表面形貌和官能團進行分析。SEM結果表明，低階煤表面疏松，含有大量孔隙與裂隙，不利于藥劑在煤表面的鋪展。FTIR和XPS結果表明低階煤表面含有大量含氧官能團，表面疏水性較差，導致浮選回收率較低。對不同捕收劑條件下氣泡與煤表面粘附力進行測定，發現氣泡與煤表面間最大粘附力隨捕收劑不飽和程度增加而增加，這說明顆粒可浮性增加。進一步對不飽和脂肪酸吸附的分子動力學模擬進行分析，可知不飽和脂肪酸通過其極性基團與煤表面極性基團間形成氫鍵，從而在煤表面鋪展。雙鍵個數增加使得不飽和脂肪酸極性增加，在煤表面的鋪展程度逐漸增加，導致顆粒可浮性增加，這是低階煤浮選回收率隨脂肪酸不飽和程度增加而增加的主要原因。
- 低階煤浮選 /
- 脂肪酸不飽和度 /
- 雙鍵 /
- 分子動力學模擬 /
- 最大粘附力
Abstract: To study the effect of fatty acid unsaturation on low-rank coal flotation, oleic acid, linoleic acid, and linolenic acid with the same number of carbon atoms but an increasing number of double bonds were selected as flotation collectors and compared with conventional nonpolar collector diesel oil. Adhesion force measurements between particles and bubbles and molecular dynamics simulation of reagent adsorption were used to reveal the mechanism of unsaturated fatty acids enhancing low-rank coal flotation. The flotation results show that unsaturated fatty acid collectors surpass nonpolar diesel oil in flotation performance, and the flotation yield of low-rank coal increases with fatty acid unsaturation. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) were used to analyze the surface morphology and surface functional groups of low-rank coal. SEM results show that the surface of low-rank coal is loose and contains many pores and cracks, which is not conducive to the spreading of chemicals on coal surfaces and the mineralization of bubbles and particles. The results of FTIR and XPS show that the surface of low-rank coal contains several oxygen-containing functional groups and has poor hydrophobicity, resulting in low flotation recovery. The adhesion force between bubbles and coal surfaces was measured in different collector solutions. The maximum adhesion between bubbles and coal surfaces increased with collector unsaturation in diesel oil, oleic acid, linoleic acid, and linolenic acid systems, indicating an increase in the floatability of coal particles with collector unsaturation. Furthermore, the molecular dynamics simulation of unsaturated fatty acid adsorption showed that unsaturated fatty acids spread on coal surfaces through hydrogen bonding between the polar groups of these molecules and surfaces. With an increasing number of double bonds, unsaturated fatty acids become more polar, and the spread of unsaturated fatty acids on coal surfaces gradually becomes more extensive, which leads to increasing particle floatability. This is the main reason for the increase in flotation recovery of low-rank coal with unsaturated fatty acids.
- low-rank coal flotation /
- fatty acid unsaturation /
- double bond /
- molecular dynamics simulation /
- maximum adhesion force

HTML全文

圖 1 粘附力測試系統原理圖^[20]

Figure 1. Schematic diagram of adhesion force measurement system^[20]

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圖 2 分子結構。（a）Wender模型^[21]；（b）水分子；（c）油酸分子；（d）亞油酸分子；（e）亞麻酸分子 (紅色：氧原子；白色：氫原子；灰色：碳原子）

Figure 2. Molecular structures of (a) Wender model^[21]; (b) hydrone; (c) oleic acid molecule; (d) linoleic acid molecule; (e) linolenic acid molecule (The colors are shown as follows: red, oxygen atoms; white, hydrogen atoms; gray, carbon atoms)

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圖 3 SEM不同放大倍數下低階煤的表面形貌.（a）300；（b）500；（c）900

Figure 3. Surface morphology of low-rank coal with different magnifications of SEM: (a) 300; (b) 500; (c) 900

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圖 4 低階煤表面紅外光譜分析

Figure 4. FTIR spectrum of the low-rank coal

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圖 5 低階煤XPS寬譜掃描

Figure 5. XPS survey scan spectrum of the low-rank coal

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圖 6 低階煤窄掃C1s分峰

Figure 6. XPS C1s peak of the low-rank coal

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圖 7 不飽和脂肪酸對低階煤浮選產率和灰分的影響.（a）浮選精煤產率；（b）浮選精煤灰分

Figure 7. Effect of unsaturated fatty acids on flotation yield and ash content of low-rank coal: (a) yield of flotation concentration; (b) ash content of flotation concentration

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圖 8 捕收劑含量為500 g·t^–1時氣泡與煤表面的力曲線. （a）柴油；（b）油酸；（c）亞油酸；（d）亞麻酸

Figure 8. Force curves between air bubble and coal surface when collector concentration is 500 g·t^–1:(a) diesel oil; (b) oleic acid; (c) linoleic acid; (d) linolenic acid

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圖 9 捕收劑含量為1000 g·t^–1時氣泡與煤表面的力曲線. （a）柴油；（b）油酸；（c）亞油酸；（d）亞麻酸

Figure 9. Force curves between air bubble and coal surface when collector concentration is 1000 g·t^–1:(a) diesel oil; (b) oleic acid; (c) linoleic acid; (d) linolenic acid

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圖 11 捕收劑用量對氣泡與煤樣最大表面粘附力與脫落力的影響.（a）500 g·t^–1；（b）1000 g·t^–1；（c）2000 g·t^–1

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圖 12 不同捕收劑用量下氣泡與煤表面最大粘附力

Figure 12. Max adhesion forces between air bubbles and coal surfaces with different dosages of collectors

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圖 10 捕收劑含量為2000 g·t^–1時氣泡與煤表面的力曲線.（a）柴油；（b）油酸；（c）亞油酸；（d）亞麻酸

Figure 10. Force curves between air bubble and coal surface when collector concentration is 2000 g·t^–1:(a) diesel oil; (b) oleic acid; (c) linoleic acid; (d) linolenic acid

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圖 13 不飽和脂肪酸在煤/水界面的吸附結構.（a）油酸；（b）亞油酸；（c）亞麻酸（局部放大圖中藍色鍵為氫鍵）

Figure 13. Adsorption structure of unsaturated fatty acids at coal/water interface: (a) oleic acid; (b) linoleic acid; (c) linolenic acid (the blue bond in partial enlargement is hydrogen bond)

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圖 14 脂肪酸分子與水分子在煤/水界面的相對濃度分布.（a）油酸；（b）亞油酸；（c）亞麻酸

Figure 14. Relative concentration distributions of fatty acids and water molecules at the coal/water interface: (a) oleic acid; (b) linoleic acid; (c) linolenic acid

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表 1 煤樣工業分析（質量分數）

Table 1. Proximate analysis of the coal sample %

M_ad	A_ad	V_daf	FC_daf
11.16	9.10	32.81	61.08
Note: ad—air dried basis；daf—dry ash free basis.

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表 2 低階煤粒度組成分析

Table 2. Particle size and ash content distributions of low-rank coal

Size / mm	Yield / %	Ash / %	Positive cumulative
Size / mm	Yield / %	Ash / %	Yield / %	Ash / %
>0.500	0.33	11.88	0.33	11.88
0.500~0.250	39.91	7.86	40.24	7.89
0.250~0.125	25.15	7.64	65.39	7.79
0.125~0.074	8.31	7.31	73.69	7.74
0.074~0.045	9.23	8.13	82.92	7.78
<0.045	17.08	12.02	100.00	8.51
Total	100.00	8.51	^—	^—

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表 3 低階煤密度組成分析

Table 3. Density analysis of low-rank coal

Density grades / (g·cm^–3)	Yield / %	Ash / %	Cumulative floate		Cumulative sink
Density grades / (g·cm^–3)	Yield / %	Ash / %	Yield / %	Ash / %	Yield / %	Ash / %
<1.3	3.35	1.54	3.35	1.54	100.00	8.02
1.3–1.4	56.95	3.58	60.30	3.47	96.65	8.24
1.4–1.5	31.95	7.20	92.26	4.76	39.70	14.93
1.5–1.6	3.83	24.48	96.09	5.55	7.75	46.79
1.6–1.8	0.84	55.76	96.93	5.98	3.92	68.58
>1.8	3.08	72.08	100.00	8.02	3.08	72.08
Total	100.00	8.02	—	—	—	—

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表 4 低階煤表面元素組成及相對含量（質量分數）

Table 4. Surface element composition and relative contents of low-rank coal %

C	O	N	Mg	Ca	Si	Al	Na
72.17	19.74	0.97	0.09	0.92	3.41	2.55	0.16

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表 5 低階煤表面官能團組成及相對含量（質量分數）

Table 5. Relative contents of functional groups on surface of low-rank coal %

C–C/C–H	C–O	C=O	O=C–O
63.53	25.01	7.54	3.92

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