Extraction of aluminum and iron from coal gangue by low temperature neutralization-pressure acid leaching

doi:10.16085/j.issn.1000-6613.2020-1529

Abstract

Abstract:

In order to solve the problems of high acid consumption, low acid utilization rate and the difficulty in separating aluminum and iron during their industrial extraction from coal gangue(CG), low-temperature neutralization-pressure acid leaching is adopted for the first time to achieve high-efficient extraction of aluminum and iron from the CG from Panzhou, Guizhou province. The optimal process conditions for the room temperature neutralization process are as follow: the acid is 20% of the theoretical consumption, the leaching time is 120min, and the mass ratio of sulfuric acid solution to solid is 3∶1. With the neutralized slag as raw material, the optimal process conditions for the pressurized acid leaching process are as follow: leaching time of 120min, leaching temperature of 150℃, and the mass ratio of sulfuric acid solution to solid of 3.5∶1 with the theoretical acid consumption of CG. Under the aforementioned conditions, the leaching rates of aluminum and iron were 95.77%, 98.37% respectively, and the contents of silicon and titanium in acid residue ash were 90.2%, 9.18% respectively. The fresh coal gangue was neutralized with the recycled acid leaching solution, yielding the concentrations of aluminum and iron in the extract solution of 62.20g/L, 57.95g/L respectively. Compared with the conventional acid leaching process, the acid consumption by the two-step process is lower, and the acid utilization efficiency is higher. Through the characterizations of the CG and slag by X-ray diffractometer (XRD), Fourier infrared spectrometer (FTIR) and Scanning electron microscope (SEM), the mechanism of carbonic acid leaching process in gangue was preliminarily analyzed. This work provides a new route and theoretical support for the industrial extraction of aluminum and iron from CG.

Key words: coal gangue, neutralization, pressure acid leaching, aluminum, iron

摘要：

以贵州盘县煤矸石为研究对象，为解决其工业生产提取铝铁时酸耗量大、酸利用率低及后续铝铁产品分离困难等问题，根据其矿物组成特点，本文首次采用低温中和-加压酸浸工艺对铝铁提取进行了详细研究。室温下中和最优工艺条件为20%理论酸耗、浸出时间120min、液固比3∶1（硫酸溶液与固体的质量比，以g/g计）；以中和渣为原料，煤矸石理论酸耗为基础，加压酸浸最优工艺条件为浸出时间120min、浸出温度150℃、液固比3.5∶1（硫酸溶液与固体的质量比，以g/g计）。在此条件下，氧化铁浸出率为98.37%，氧化铝浸出率为95.77%，酸浸渣灰分中氧化硅质量分数为90.2%，氧化钛质量分数为9.18%。以最优工艺条件下的酸浸液循环中和新鲜煤矸石，得到的铝铁提取液中氧化铁浓度为57.95g/L，氧化铝浓度为62.20g/L。相比常规酸浸工艺具有酸耗低、酸利用率高等优点。借助X射线衍射仪（XRD）、傅里叶红外光谱仪（FTIR）和扫描电子显微镜（SEM）等分析手段，初步对两步溶出过程进行了机理分析，为煤矸石工业生产提取铝铁提供了新路线和理论支撑。

关键词: 煤矸石, 中和, 加压酸浸, 铝, 铁

CLC Number:

X752

LI Haolin, ZENG Dehui, ZHENG Guangya, XIA Jupei. Extraction of aluminum and iron from coal gangue by low temperature neutralization-pressure acid leaching[J]. Chemical Industry and Engineering Progress, 2021, 40(7): 4011-4020.

李浩林, 曾德恢, 郑光亚, 夏举佩. 低温中和-加压酸浸提取煤矸石中铝铁[J]. 化工进展, 2021, 40(7): 4011-4020.

Figures/Tables 13

成分	质量分数/%	成分	质量分数/%
SiO₂	39.41	MgO	2.06
TiO₂	4.43	K₂O	1.72
Fe₂O₃	12.38	Na₂O	0.71
Al₂O₃	18.52	烧蚀量	17.4
CaO	2.92

热力学函数	$F e C O 3 + H 2 S O 4 ? ??????????? F e S O 4 + H 2 O + C O 2 (g)$	$M g C O 3 + H 2 S O 4 ? ??????????? M g S O 4 + H 2 O + C O 2 (g)$	$C a C O 3 + H 2 S O 4 ? ??????????? C a S O 4 + H 2 O + C O 2 (g)$
?H/kJ·mol^-1	-49.13	-26.74	-91.84
?G/kJ·mol^-1	-95.54	-72.64	-134.71

热力学函数	$F e C O 3 + H 2 S O 4 ? ??????????? F e S O 4 + H 2 O + C O 2 (g)$	$M g C O 3 + H 2 S O 4 ? ??????????? M g S O 4 + H 2 O + C O 2 (g)$	$C a C O 3 + H 2 S O 4 ? ??????????? C a S O 4 + H 2 O + C O 2 (g)$
?H/kJ·mol^-1	-49.13	-26.74	-91.84
?G/kJ·mol^-1	-95.54	-72.64	-134.71

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