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In order to achieve efficient resource utilization of metal tailings, taking the roasted clinker of silver tailings (RCST) as the object, the dissolution behaviors of Si, Al and Fe in the water–acid two-stage leaching process and the water leaching kinetics of Si were investigated in this study. Single-factor experiments were performed to investigate the effects of the leaching parameters; the XRF, XRD and SEM-EDS methods were used to characterize the leaching residues with different leaching times, and the leaching kinetics models of Si were established. The results demonstrate that, in the water leaching stage, the sodium silicate and a small part of the structurally unstable sodium aluminosilicate in RCST are dissolved, while the nepheline, most of the sodium aluminosilicate and the mixed materials containing iron enter the water leaching residue. The first 5 min of water leaching is controlled by both interfacial transfer and diffusion across the product layer, with an apparent activation energy of 22.36 kJ/mol, and the dissolution reaction during 5–15 min is controlled by the unsteady diffusion of the liquid film, with an apparent activation energy of 14.22 kJ/mol. The structure of the materials in the clinker is completely destroyed, and a great number of fissures and pores are produced by the continued dissolving action of the water. Thus, in the acid leaching stage, the amorphous Si-, Al- and Fe-containing substances in the water leaching residue are rapidly dissolved in the sulfuric acid solution at a lower temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • Diaspore and kaolinite can transform into Na 2-x Al 2-x Si x O 4 by reacting with Na 2 CO 3. • The transformation is affected by temperature and the amount of Na 2 CO 3. • The leaching performance of Na 2-x Al 2-x Si x O 4 is negatively correlated with x value. A series of sodium aluminosilicates (Na 2-x Al 2-x Si x O 4 , x = 0.85, 0.55, 0.45, 0.35, 0.25 and 0.05) can be generated in the soda sintering process, some of which can be dissolved in sodium aluminate solution. This paper focuses on the transformation of aluminum-bearing minerals into Na 2-x Al 2-x Si x O 4 during the calcination of diasporic bauxite with different proportions of Na 2 CO 3 at 400–1100 °C. Based on thermodynamic analysis, the thermal behaviors, phase transformations and bonding changes of the aluminum-bearing minerals are investigated using thermogravimetric analysis and differential scanning calorimetric (TGA-DSC), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) techniques. In addition, the dissolution performances of some Na 2-x Al 2-x Si x O 4 are verified by water leaching. The results demonstrate that the aluminum-bearing minerals in diasporic bauxite are diaspore and kaolinite, which are converted into Na 2-x Al 2-x Si x O 4 after calcination with Na 2 CO 3 at 700–1100 °C. Increasing the calcination temperature in the range of 700–1000 °C and the proportion of Na 2 CO 3 results in Na 2-x Al 2-x Si x O 4 having lower x value and decomposing into NaAlO 2 and Na 2 SiO 3 if Na 2 CO 3 is present in excess. As the mass ratio of bauxite to Na 2 CO 3 is 1, Na 1.95 Al 1.95 Si 0.05 O 4 is primarily formed at 900–1000 °C, which has excellent dissolution performance, close to that of NaAlO 2. Upon further increasing the calcination temperature to 1100 °C, Na 1.95 Al 1.95 Si 0.05 O 4 transforms into Na 2-x Al 2-x Si x O 4 with a higher x value, which has worse dissolution performance. [ABSTRACT FROM AUTHOR]