A novel process for preparing direct reduction iron (DRI) and titanium nitride (TiN) from Panzhihua titanomagnetite concentrate is proposed. This process involves pelletizing, direct reduction roasting and magnetic separation. The effects of reduction temperature, coal dosage and reduction time on the phase transformation of composite pellets were investigated by X-ray diffraction. Results show that TiN formation proceeds less easily than metallic iron formation. Increasing the reduction temperature, reduction time and coal dosage can promote the transformation of titanium to TiN. Titanium was almost completely transformed into TiN under the conditions of 1300 °C reduction temperature, 26 wt % coal dosage and 90 min reduction time. The scanning electron microscopy (SEM) analysis showed that near-spherical metallic iron particles with diameters from dozens of microns to about 300 μm were formed in the reduced pellets, whereas the TiN particles generally measured less than 10 μm. The energy dispersive spectroscopy (EDS) results revealed that the TiN phase contains a certain amount of vanadium and carbon, and traces of other impurities. The reduced composite pellets under the optimum conditions were processed by grinding and subsequent magnetic separation. As a result, a DRI with 92.88 wt % Fe, 1.00 wt % Ti, and 0.13 wt % V was obtained, and the recoveries of Fe, Ti, and V were 92.85 wt %, 9.00 wt %, and 19.40 wt %, respectively. 91.00 wt % Ti and 80.60 wt % V were concentrated in the rough TiN concentrate.

Excessive ammonia is a common pollutant in the wastewater, which can cause eutrophication, poison aquatic life, reduce water quality and even threaten human health. Ammonia in aqueous solution was converted using various systems, i.e., ozonation (O₃), ultrasound (US), catalyst (SrO-Al₂O₃), ultrasonic ozonation (US/O₃), ultrasound-enhanced SrO-Al₂O₃ (SrO-Al₂O₃/US), SrO-Al₂O₃ ozonation (SrO-Al₂O₃/O₃) and ultrasound-enhanced SrO-Al₂O₃ ozonation (SrO-Al₂O₃/US/O₃) under the same experimental conditions. The results indicated that the combined SrO-Al₂O₃/US/O₃ process achieved the highest NH₄⁺ conversion rate due to the synergistic effect between US, SrO-Al₂O₃ and O₃. Additionally, the effect of different operational parameters on ammonia oxidation in SrO-Al₂O₃/O₃ and SrO-Al₂O₃/US/O₃ systems was evaluated. It was found that the ammonia conversion increased with the increase of pH value in both systems. The NH₃(aq) is oxidized by both O₃ and ·OH at high pH, whereas the NH₄⁺ oxidation is only carried out through ·OH at low pH. Compared with the SrO-Al₂O₃/O₃ system, the ammonia conversion was significantly increased, the reaction time was shortened, and the consumption of catalyst dosage and ozone were reduced in the SrO-Al₂O₃/US/O₃ system. Moreover, reasonable control of ultrasonic power and duty cycle can further improve the ammonia conversion rate. Under the optimal conditions, the ammonia conversion and gaseous nitrogen yield reached 83.2% and 51.8%, respectively. The presence of tert-butanol, CO₃²⁻, HCO₃⁻, and SO₄²⁻ inhibited the ammonia oxidation in the SrO-Al₂O₃/US/O₃ system. During ammonia conversion, SrO-Al₂O₃ catalyst not only has a certain adsorption effect on NH₄⁺ but accelerates the O₃ decomposition to ·OH.

The galvanic interaction between chalcopyrite and monoclinic pyrrhotite and its effect on flotation separation were studied using monomineral flotation tests, adsorption capacity tests, X-ray photoelectron spectroscopy (XPS) characterization, and scanning electron microscopy (SEM) test. These results showed that the interaction promoted the reduction of O₂ on the cathodic chalcopyrite surface and accelerated the generation of Fe(OH)₃, which was not conducive to collector adsorption; hence, the flotation recovery decreased by 10–16%. On the other hand, galvanic interaction accelerated the oxidation of S on the anodic monoclinic pyrrhotite surface to S₀ or SO₄²⁻ and produced a large amount of H⁺, thus preventing the formation of Fe(OH)₃. Meanwhile, the Cu²⁺ eluted from chalcopyrite surface activated monoclinic pyrrhotite; hence, the flotation recovery increased by 3–10%. Galvanic interaction reduced the floatability difference between the two minerals, and the separation difficulty was significantly increased. Even with an increase in the amount of lime, the separation could not be improved.