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Selective comminution and grinding mechanisms of spent carbon anode from aluminum electrolysis using ball and rod mills

Ni Chao, Zhou Shaoqi, Gao Jixuan, Bu Xiangning, Chen Yuran, Alheshibri Muidh, Xie Guangyuan, Li Biao

Physicochemical Problems of Mineral Processing

2022

Vol. 58, iss. 3

art. no. 145667

The recovery of spent carbon anode (SCA) materials plays important roles in environment protection and resources recycling, while this cannot be efficiently achieved without liberation. In this study, grinding characteristics of spent carbon anode from aluminum electrolysis in both ball mill and rod mill were analyzed, and compared based on the utilization of the selective Fuerstenau upgrading curves. In addition, the different grinding mechanisms of ball and rod milling were evaluated by analyzing the shape factor and surface roughness of the ground samples. Results of mineralogical characterizations indicated that carbon particles (d50 = 46.86 μm) presented in the SCA were closely associated with cryolite particles. At 5 min grinding time, the maximum selective comminution factor (β) values of ball milling and rod milling were 2.00 and 1.63, respectively, indicating a higher degree of selective comminution of SCA was achieved from ball milling. Comparisons of the valuable component content (cv, cum) of -125 μm ground particles and the shape characterizations of 74–125 μm ground particles generated from ball and rod milling manifest that a direct relationship exists between the degree of selective comminution and the grinding mechanism.

Effects of monovalent and divalent ions in coal gasification brine on the froth entrainment and flotation kinetics of anthracite coal

Zheng Kaidi, Bu Xiangning, Zhou Shaoqi, Zhang Jing, Shao Huaizhi, Sha Jie, Xie Guangyuan

Physicochemical Problems of Mineral Processing

2020

Vol. 56, iss. 5

960--974

Water plays a critical role in various stages of flotation, which brings a lot of pressure to the flotation processing plants resided in dry areas. In this regard, it will be of significance to explore the feasibility of using wastewater resources in mineral flotation. Coal gasification brine (CGB) that contains a high concentration of salts becomes the subject of interest of this study. In this study, a synthetic CGB solution, which was prepared by adding NaCl, MgCl2, and CaCl2 to ultrapure water based on the composition of salts in a real CGB, was used in the flotation of anthracite coal. The comparison results based on the first-order model showed that flotation in the presence of the synthetic CGB solution gave a higher flotation selectivity (SI =7.086) than that of flotation in ultrapure water (SI=3.545). Water recoveries and average bubble sizes in the froth showed that the addition of the three salt ions (Na+, Mg2+, and Ca2+) was conducive to diminishing the entrainment of gangue materials as a result of the reduction of water reporting to the froth. Additionally, the zeta potentials and induction time measurements indicated that only divalent ions of Ca2+ and Mg2+ significantly compressed the double electrical layer and enhanced the attachment between bubbles and coal particles according to DLVO theory, which was further confirmed by the calculation of interaction energy between coal and bubbles. The findings of the present work may promote the use of CGB as a potential water resource in coal flotation.