In this paper, the effect of pyrite on the activation of sphalerite was investigated by micro-flotation, copper adsorption experiments, X-ray photoelectron spectroscopy (XPS), and electrochemical measurement. The micro-flotation test results showed that the recovery and flotation rate of sphalerite with copper sulphate as activator and butyl xanthate as collector were significantly decreased with the increasing content of pyrite in pulp. Cu²⁺ adsorption results indicated that the adsorption of Cu²⁺ on the sphalerite surface were decreased when pyrite was present in the pulp. XPS surface analysis demonstrated that the proportion of Cu⁺ species increased in the activation products on the sphalerite surface, but the total atomic concentration of Cu atom was decreased. Linear voltammetry measurement suggested that the current density of Cu⁺ species oxidizing to Cu²⁺ species was increased when sphalerite was electrically contacted with pyrite, which confirmed the increased proportion of Cu⁺ species on Cu-activation sphalerite surface when contacting with pyrite. These results indicated that there is not only a competitive adsorption for cupric ions (Cu²⁺), but the galvanic interaction between sphalerite and pyrite also has a significant influence on the copper activation of sphalerite.

In this paper, the adsorption of cyanide and its combination with zinc sulfate on the surface of sphalerite (110) was studied by density functional theory (DFT), and its configurational relationship was analyzed by coordination chemistry. The calculation results show that the adsorption configuration stability of CN⁻ is stronger than that of Zn(CN)₂; the chemical bond of Zn(OH)₂ is less covalent. The three adsorption modes all make the surface of sphalerite lose more electrons, thereby weakening the reactivity of S and Zn atoms on the sphalerite surface. During the CN⁻ adsorption process, both the 3d and 4p orbital peak energy levels of Zn decrease, indicating the strong inhibitory effect of CN⁻. Coordination chemistry also shows that CN⁻ matches the Zn ion orbital in sphalerite and the π electron pair on the Zn ion can easily interact with the empty π orbital on CN⁻ to form π-backbonding.

The crystallization kinetics of picromerite play a crucial role in optimizing the fertilizer quality. This study developed a crystallization kinetics model of picromerite. Results show that increasing temperature mainly leads to higher supersaturation, which, in turn, enhances both nucleation and growth rates, with significant improvements in crystal size and uniformity. Higher stirring speed was found to have positive effects on crystal nucleation and growth rate. The decrease in supersaturation leads to the diminution of the driving force for crystallization and the gradual decline in crystallization. The study provides a comprehensive analysis of the relationships between these crystallization conditions and the resultant crystal properties.

The complex mineral composition and heterogeneous intergrowth characteristics of copper–tin polymetallic sulfide ores make it difficult to obtain an appropriate particle-size distribution and sufficient mineral liberation during grinding, which can affect subsequent separation. This study investigated the effects of sodium tripolyphosphate (STPP) as a grinding aid on a copper–tin polymetallic sulfide ore from the Datun Plant in Gejiu, Yunnan, China. Grinding and separation tests, together with mineralogical and surface characterization using MapsMin, SEM-EDS, zeta-potential and contact-angle measurements, and DLVO/EDLVO calculations, were conducted to evaluate the effects of STPP on grinding and subsequent separation. The grinding results showed that, compared with the lime-only condition (0.10 wt% lime), the addition of 0.025 wt% STPP increased the proportion of the target size fraction (−0.15 + 0.019 mm) by 1.76%, without a marked increase in the fine fraction (−0.019 mm) or the coarse fraction (+0.15 mm). Compared with the lime-only condition, the addition of 0.025 wt% STPP increased the grade and recovery of the copper flotation concentrate by 0.20% and 3.54%, respectively, and those of the cassiterite gravity concentrate by 0.44% and 14.31%, respectively. The overall Sn recovery of the combined gravity separation and flotation process increased from 92.58% under the lime-only condition to 93.56% with the addition of 0.025 wt% STPP, but decreased to 92.39% when the STPP dosage was increased to 0.050 wt%. Automated mineralogical analysis showed that STPP addition increased the complete liberation degrees of cassiterite and bornite, while varying degrees of improvement were also observed for other major minerals. With the addition of 0.025 wt% STPP, the maximum particle size decreased from 820.95 to 495.30 μm, and D90 decreased from 374 to 237 μm relative to the lime-only condition. Surface characterization and DLVO/EDLVO analysis indicated that STPP altered mineral surface properties and interparticle interactions, which may have contributed to the observed changes in particle-size distribution and mineral liberation.

Different activation mechanisms of Cu²⁺ and Pb²⁺ in stibnite flotation were studied via microflotation and adsorption capacity tests and density functional theory (DFT). Microflotation experiments indicated that the recovery rate of stibnite flotation with butyl xanthate (BX) was activated 7.82% higher by Pb²⁺ than Cu²⁺. The presence of Pb²⁺ increased the amount of adsorbed BX on the stibnite surface. The results of DFT also suggested stronger activation by Pb²⁺. Cu²⁺ activation induced the formation of Cu-S bonds between the double-bonded S1 atom of BX with Cu, resulting in electron gain. Pb²⁺ activation was followed by the formation of a stable chelating structure between single-bond S1 and double-bond S2 atoms of BX, resulting in electron loss. This system also facilitated dixanthate formation on the mineral surface via interaction between BX and oxygen, thus improving the floatability of stibnite. This study lays a theoretical foundation for the efficient recovery of stibnite.