Basic Characteristics of Hemimorphite and Its Transformation Mechanism with Na2CO3

Abstract

The crystal of hemimorphite is a non-conductor. The Si-O bond in the crystal is strong, whereas the Zn-O bond is weak. These properties lead to the easy breakage of the Zn-O bond in the crushing process of hemimorphite. Thus, the interaction between minerals and polar water molecules is strong, and natural floatability of ores is poor. This study systematically investigated the characteristics of hemimorphite and its action mechanism with Na 2 CO 3. Results of SEM-EDS showed that the surface of hemimorphite dissolved after interacting with Na 2 CO 3 , and the contents of Si and O decreased, whereas Zn and C increased. XPS analysis showed that the carbonate group was detected. The interaction between CO 3 2− and hemimorphite was calculated using the first principles calculation based on density functional theory. The results indicate that an O atom in CO 3 2− interacted with Zn 2+ from the (100) plane of hemimorphite. The interaction between Zn and O atoms was not strong, and the Zn atoms were not completely displaced, which was proven by density of state analysis and the EDS and XPS results. The Mulliken population showed that the O-Zn bond was the atomic bonding of CO 3 2− with Zn 2+ and exhibited properties of ionic bonds. Thus, hemimorphite transformed to smithsonite-like mineral (ZnCO 3) when acting with CO 3 2− .

Recent Progress on Chelating Reagents in Flotation of Zinc Oxide Ores: A Review

“…Moreover, th smithsonite surface is partially hydroxylated to form zinc hydroxides in alkaline condi tions, which hinders the interaction between flotation reagents and active sites on the sur faces of the minerals. Hemimorphite is a complex silicate mineral whose structure is shown in Figure 1b In the crystal structure of hemimorphite, Zn atoms form new tetrahedra with -OH and three O atoms belonging to the Si-O tetrahedron, resulting in low Zn activity in the lattic [35]. The bonding strength between the Si-O bonds being stronger than that between th Hemimorphite is a complex silicate mineral whose structure is shown in Figure 1b.…”

“…The bonding strength between the Si-O bonds being stronger than that between th Hemimorphite is a complex silicate mineral whose structure is shown in Figure 1b. In the crystal structure of hemimorphite, Zn atoms form new tetrahedra with -OH and three O atoms belonging to the Si-O tetrahedron, resulting in low Zn activity in the lattice [35]. The bonding strength between the Si-O bonds being stronger than that between the Zn-O bonds leads to the breaking of the Zn-O bonds during the crushing and grinding process of hemimorphite.…”