低温中和-加压酸浸提取煤矸石中铝铁

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。

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

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.