The comprehensive recycling ways for tailings after vanadium extraction, including recovery of valuable components, synthesis of new functional materials and preparation of multi-purpose building materials, were explained, which can provide a reference for application of technologies in comprehensive recycling of tailings after vanadium extraction.

Beneficiation tests were conducted to process the low-grade cobalt-nickel ore from Hebei Province by adopting an asynchronous flotation flowsheet consisting sequentially of staged grinding, flotation of sulfide minerals and flotation of sulfurized oxide minerals. In the study, combined depressants were used for better depressing of slime, while regrinding process was introduced to intensify the sulfurization effect. Finally, a cobalt-nickel sulfide concentrate with Co grade of 2.00% and Ni grade of 3.90% and a cobalt-nickel oxide concentrate with Co grade of 1.47% and Ni grade of 2.73% were obtained. The total Co recovery and total Ni recovery reached 77.61% and 79.20%, respectively. In this way, the preliminary enrichment and recovery of Co and Ni resources can be realized, laying a foundation for their further purification.

By means of X-ray diffraction, optical microscopy, scanning electronic microscopy, mineral liberation analysis and chemical analysis, the paigetite ore from Wengquangou mine in Liaoning Province was studied in terms of its chemical component, mineral composition and content, and the occurrence state of main minerals. After main dissemination characteristics of target minerals and key factors in mineralogy influencing beneficiation performance were ascertained, some corresponding separation techniques were proposed.

The lifting of polymetallic nodules was simulated by using a CFD-DEM coupling approach, and the influence of different swirling flow on hydraulic lifting of polymetallic nodules in vertical pipelines was explored. The results show that as swirl ratio increases, the intensity of swirl will be enhanced significantly, and both the maximum fluid velocity and the average axial velocity of particle group will increase. It is found that intensity of swirl can bring obvious impact to the distribution of particles with different velocity in the pipe, showing that particles with high velocity are gradually distributed around the pipe wall, while the particles with low velocity in the center of the pipe. Swirling flow can reduce the local concentration of particles, which is beneficial to reducing the risk of pipeline blockage due to higher concentration of particles caused by retention effect.

The key factors of pile foundation settlement were explored for the slope under vertical load by using grey relational analysis, and it is found that each factor is in the following descending order by its influence: elastic modulus > slope distance > slope gradient > internal friction angle > cohesion > soil density > poisson's ratio of soil > pile length > pile diameter. In order to optimize the parameters of support vector regression (SVR) model, a novel HGWO-SVR model was proposed by integrating the differential evolution-enhanced gray wolf algorithm (HGWO). Compared with GWO-SVR and GS-SVR models, this model presents obvious advantage in prediction, with high accuracy and minor error. A settlement prediction model for pile foundation of slope was constructed based on HGWO-SVR model, and the prediction results were compared with those values calculated with existing settlement formulas. The results show that the maximum percentage error between the prediction value of HGWO-SVR model and the calculated value is 6.55%, thus verifying that this model is feasible in settlement prediction for pile foundation of slope.

In order to avoid formation of material ring in a rotary kiln caused by kiln phosphoric acid process, a technique of high-temperature consolidation of pellets was proposed, and the effects of types of binder, temperature and time of consolidation on the strength and reducibility of phosphate ore pellets were investigated. The results show that consolidation at a temperature over 800 ℃ with bentonite as binder can lead to the pellets with compressive strength and drop numbers obviously higher than those with sodium humate as the binder. With an addition of carbon at 1.4 times of the theoretical amount, CaO and SiO₂ at a molar ratio of 0.35, an addition of bentonite at an amount of 1.5% of the total material weight, consolidation at 1 000 ℃ for 30 min results in the produced pellets with compressive strength of 345.36 N and drop numbers of 33.50.

To utilize efficiently valuable metal resources containing lithium and beryllium, flotation experiments were conducted based on the study of ore properties. A lithium-beryllium bulk flotation process was used and the influences of dosages of regulator, activator and collector, and the stirring time of regulator on the flotation performance of lithium polymetallic ore were investigated. Based on the determined optimal dosages of calcium chloride and collectors of GYLZ and GYM3, a closed-circuit test produced a lithium concentrate with Li₂O grade and recovery of 6.10% and 94.01% respective, and BeO grade and recovery of 0.12% and 88.53%, respectively, achieving efficient recovery and utilization of lithium and beryllium resources in lithium polymetallic ores.

Experiments were carried out to compare dephosphorization performance of CaCO₃, Na₂CO₃ and CaF₂ in direct reduction roasting process of high-phosphorus hematite. It is found that Na₂CO₃ presents the best dephosphorization performance, followed by CaCO₃. The molecular dynamics simulation was conducted to calculate the distribution of bridging oxygen and the mean square displacement (MSD) of oxygen atoms during the roasting process of the system with three different additives respectively, and the dephosphorization mechanism of CaCO₃, Na₂CO₃, CaF₂ during the direct reduction process of high-phosphorus hematite was explored. The results show that the mechanism of dephosphorization by additives is to inhibit reduction of apatite by increasing the content of free oxygen or the MSD of oxygen atoms in the system and reducing the oxygen atoms shared by Si and P in the system. It is found that the dephosphorization performance of additives is positively correlated with the MSD of oxygen atoms in the system.

The effects of brightening agent, such as polysodium dithiodipropanesulfonate (SPS) and sodium 3-mercapto-1-propanesulfonate (MPS), on electrodeposition of Cu from electrolyte with Cu²⁺, H₂SO₄, Cl^- concentration of 85 g/L, 100 g/L and 20 mg/L respectively were studied by adopting linear scanning voltammetry and cyclic voltammetric stripping (CVS), and the effects of SPS and MPS on the tensile strength, elongation, glossiness and roughness of electrolytic copper foil for Li-ion batteries were discussed. The results show that SPS and MPS can promote copper electrodeposition, and also SPS is better than MPS in promotion. However, the compounding with collagen and hydroxyethylcellulose will result in less promotion of copper electrodeposition. In addition, SPS is conducive to improving the tensile strength of copper foil, and MPS is conducive to improving the elongation of copper foil. With concentration of SPS and MPS at 1 mg/L and 1.5 mg/L respectively, the prepared copper foil has flat and dense surface, with better glossiness and roughness.

A kind of contaminated paddy soil was taken for pot experiment by adding FeSO₄ to investigate the impact of FeSO₄ on the formation of iron plaques on the root surface and the migration of the Cd from Cd-contaminated paddy soil. Results show that with the addition of FeSO₄ increased from 0 to 320 mg/kg, the pH value of the paddy soil tends to decline, maximally by 0.70. The TCLP-Cd content in the potting soil rises to a certain extent compared to the control group. The addition of FeSO₄ significantly reduces the Cd content in leaves, husks, and brown rice, as well as effectively increases the amount of root iron plaque, thus the absorption of Cd in the soil by rice is moderately controlled. However, the addition of external iron resource can bring impact to the pH of soil and bioavailability of Cd, so it is recommended that in practical operation, FeSO₄ should be added with some alkaline restorative materials such as lime to contaminated paddy fields for enhancing the control.