Effects of sodium salt of N,N-dimethyldi-thiocarbamate on floatability of chalcopyrite, sphalerite, marmatite and its adsorption properties

The role of EDTA on rutile flotation using Al3+ ions as an activator

Rutile is a relatively stable mineral, due to its weakly specific adsorption to collectors. The development and application of a high efficiency and low-toxicity activator is the main challenge in rutile flotation. In this study, Al³⁺ ions and EDTA (ethylene diamine tetraacetic acid) as mixed activators were investigated using micro-flotation tests. The results of the micro-flotation tests showed that the flotation recovery was slightly increased (from 65.8% to 69.7%) using single Al³⁺ ions as the activator and surprisingly, the activating effect was sharply improved (from 69.7% to 80.6%) after adding EDTA. The activating mechanism of Al³⁺ ions and EDTA was revealed by adsorption capacity measurements, zeta potential measurements, FT-IR spectroscopy analysis and XPS analysis. Al³⁺ ions were adsorbed on the rutile surface in the form of Al(OH)_n³⁻ⁿ (n = 0, 1, 2), which increased the zeta potential and the activating sites for anionic collector adsorption. The addition of EDTA removed the surplus Al³⁺ ions, and prevented the generation of hydrophilic colloidal Al(OH)₃ over the pH range of optimum flotation.

The adsorption model of Al³⁺ ions, EDTA and SPA on the rutile surface.

Mechanism study on the sulfidation of ZnO with sulfur and iron oxide at high temperature

The mechanism of ZnO sulfidation with sulfur and iron oxide at high temperatures was studied. The thermodynamic analysis, sulfidation behavior of zinc, phase transformations, morphology changes, and surface properties were investigated by HSC 5.0 combined with FactSage 7.0, ICP, XRD, optical microscopy coupled with SEM-EDS, and XPS. The results indicate that increasing temperature and adding iron oxide can not only improve the sulfidation of ZnO but also promote the formation and growth of ZnS crystals. Fe₂O₃ captured the sulfur in the initial sulfidation process as iron sulfides, which then acted as the sulfurizing agent in the late period, thus reducing sulfur escape at high temperatures. The addition of carbon can not only enhance the sulfidation but increase sulfur utilization rate and eliminate the generation of SO₂. The surfaces of marmatite and synthetic zinc sulfides contain high oxygen due to oxidation and oxygen adsorption. Hydroxyl easily absorbs on the surface of iron-bearing zinc sulfide (Zn_1−xFe_xS). The oxidation of synthetic Zn_1−xFe_xS is easier than marmatite in air.