Extraction of Aluminum and Iron Ions from Coal Gangue by Acid Leaching and Kinetic Analyses

Deshun Kong,Shuojiang Song,Minglei Lian,Zihan Zhou,Rongli Jiang,Shan Feng

doi:10.3390/min12020215

Deshun Kong, Shuojiang Song + Show 4 more

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https://doi.org/10.3390/min12020215

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Abstract

Extracting valuable elements from coal gangue is an important method for the utilization of coal gangue. In order to obtain the suitable technological conditions and the acid leaching kinetic model of leaching aluminum and iron ions from high-iron and low-aluminum coal gangue, the effects of calcination temperature, calcination time, and acid types on the leaching results of aluminum and iron ions are studied. The results show that when the gangue is calcined at 675 °C for 1 h, then the calcined gangue powder is leached by 6 mol/L hydrochloric acid at 93 °C for 4 h, the leaching ratio of iron ions is more than 90%, and that of aluminum ions is more than 60%. Furthermore, the acid leaching kinetic equations at 30 °C, 50 °C, 70 °C, and 90 °C are studied by three kinetic models, and the apparent activation energies of the reactions are calculated by the Arrhenius formula. The results show that the leaching behavior of aluminum and iron ions conformed to the “mixing control” model equation: “(1 − x)−1/3 − 1 + 1/3ln(1 − x) = kt + b”. The apparent activation energies of aluminum and iron ions are 55.5 kJ/mol and 55.8 kJ/mol, respectively. All these indicate that the acid leaching process is controlled by the “mixing control”.

Highlights

Coal gangue is the waste produced by the coal industry [1], which accounts for
The results show that “the mixed control” model can explain the leaching kinetics of coal gangue samples effectively
Chemical the Coal Gangue used for CuKα (λ for Kα = 1.54059 Å), 2θ = 3°–65°, with a step width of 0.02°

Summary

Introduction

Coal gangue is the waste produced by the coal industry [1], which accounts for10–20% of the raw coal output [2]. The resource utilization of coal gangue is conducive to decreasing its ecological damage and enhancing industrial added value. The common ways to utilize gangue include mine backfilling [5], brick making [6,7], road paving [8], cement making [9], etc. These methods cannot make use of coal gangue for highvalue-added applications, so it is imperative to research a method of efficient development and comprehensive utilization of coal gangue [10,11]. Most coal gangues used in these studies have low iron content, so the purity and whiteness of the prepared products are high

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