Extraction of rhenium from low-grade molybdenum concentrate by adopting a process of oxidative volatilization followed by ion exchange was explored in experiments. Firstly, a two-stage high-temperature oxidative roasting was adopted to oxidize rhenium into Re₂O₇. Rhenium and molybdenum were effectively separated due to rhenium volatilizing into the flue gas. The volatilization rate of rhenium reached 85.42% after roasting process at 675 ℃. Then, the rhenium-containing flue gas was eluted to get rhenium-containing solution, in which rhenium was selectively extracted with D201×7 ion exchange resin. With the solution pH of 9, liquid/solid ratio of 50 mL/g, a 20 min adsorption at temperature of 35 ℃ brought the adsorption rate of Re up to 97.52% and the adsorption rate of Mo less than 20%. Finally, a product of ammonium rhenate was prepared by stepwise desorption followed by concentration and crystallization. By this process, the total recovery of Re can reach 70.68%.

An extraction system composed of P507 as the extractant and sulfonated kerosene as the diluent was used to separate zinc from a sulfuric acid leachate containing cobalt, manganese and zinc. The effects of key parameters on zinc separation efficiency were investigated, including the volume fraction of P507 in organic phase, saponification degree, pH value of feed, O/W ratio, reaction time, and reaction temperature. The results show that under the following optimal process conditions, including P507 at 20% by volume, saponification degree of 80%, feed pH of 5, O/W ratio of 1∶1, reaction time of 10 min and reaction temperature of 25 ℃, the extraction rate of Zn reaches 99.92%, while the extraction rates of Mn and Co are just 17.41% and 3.69%, respectively, presenting an excellent separation effect.

The flotation reagent system was optimized for a lead-zinc ore in Qinghai based on experimental studies. It is shown that a new chelating agent (PT-8) combined with the conventional 25^# xanthate can effectively enhance the flotation recovery of copper-lead sulfide minerals. A new collector (SXF-10) at a low dosage can efficiently recover marmatite from the ore, significantly improving the recoveries of Cu, Pb and Zn from flotation process. With raw ore at a grinding fineness of -0.074 mm 70%, 25^# xanthate and PT-8 are used for Pb flotation, and SXF-10 is used for Zn flotation. A closed-circuit test with such process flow can produce a Cu-Pb concentrate grading 3.52% Cu and 62.53% Pb at corresponding recoveries of 70.08% and 93.75%, respectively, and a Zn concentrate grading 48.19% Zn at 87.97% recovery.

Vanadium slag and sodium carbonate, as raw materials, were mixed and grounded for pretreatment. The obtained mixture was then taken in a roasting experiment for investigating effects of factors, such as holding time, temperature and feeding materials for roasting process with different alkali ratios (a mass ratio of sodium carbonate to the converted content of V₂O₅ in vanadium slag) on transformation and leaching rate of vanadium from clinker, and also exploring phase transformation of vanadium slag during the roasting with a low alkali ratio. The results show that if roasting process at higher temperatures is held for 90 minutes, the alkali ratio in the roasting process can be reduced by properly increasing the temperature. After roasting at a temperature of 880 ℃ with an alkali ratio of 1.0, water leaching can result in the total vanadium (TV) content in the residue falling down to 0.49% and the leaching rate of vanadium up to 94.70%. This method is suitable for sodium roasting in a rotary kiln. Under the existing process conditions for sodium roasting of vanadium slag in a multiple hearth furnace, an addition of some clinker into the material for roasting is beneficial to reducing the alkali ratio. It is shown that after roasting is held for 45 minutes at 780 ℃ with an alkali ratio of 1.2, the TV content in the final leaching residue can fall to 0.96% and the leaching rate can reach 89.19%. The microscopic analysis of the clinker after roasting with a low alkali ratio show that there is a high aggregation of sodium vanadate phase, which is in good consistency with NaVO₃ in the elemental composition.

With nickel laterite ore from Morowali of Indonesia as the raw material, effects of various factors, including reaction time and temperature, stirring speed, acid-to-ore ratio, and slurry concentration, on the leaching rate were systematically investigated. Additionally, the leaching mechanism was explored by using the PHREEQC, a thermodynamic calculation software. The results show that after one hour reaction at 250 ℃, with acid-to-ore ratio of 300 kg/t and slurry concentration of 25%, the leaching rates of Ni and Co can reach 98.40% and 99.90%, respectively, while the leaching rates of Fe and Al are just 3.84% and 40.25%, respectively. The high selectivity of high pressure acid leaching (HPAL) is attributed by the factor that at high temperatures, not only the hydrolysis reaction of Fe and Al can be promoted, but also the pOH can be decreased from 14 to 10, which thereby inhibits leaching of Fe and Al. As the temperature rises to above 200 ℃, the number of H⁺ increases, which can ensure a sufficient amount of H⁺ for leaching of nickel and cobalt metals.

There are well-developed faults in an open-pit molybdenum mine, which may lead to slope instability during open-pit mining. Three typical faults running through the ultimate boundary were selected to investigate progressive instability mechanism of the slopes in the open-pit mine under coupling effect of multiple faults by integrating Rhino+Griddle 3D geological modeling and FLAC^3D multi-field coupling simulation. Furthermore, the safety factors of slopes under different working conditions were calculated, and relatively unstable slopes were also identified for addressing the subsequent safety of the ultimate boundary. The simulation results show that, plastic failure and tensile stress concentration will occur in the slope at the junction of Zone C and Zone D, while local plastic failure will occur in the faults, which, however, won't induce instability failure in the surrounding slopes; there won't be much displacement in the slope at the ultimate boundary, with the maximum displacement (2.44 cm) at the toe of slope; the safety factors of the ultimate boundary of open pit under natural working conditions and rainfall are 2.48 and 2.36 respectively, indicating that the slope is stable. However, slope at Zone E with F1 fault is considered to be with a relatively instability, for which comprehensive measures including real-time monitoring, prevention and reinforcement can be taken to ensure the safety.

To analyze the damage effect of drilling and blasting in construction on the surrounding rock of roadway, a Hopkinson pressure bar (SHPB) test and numerical simulation were carried out to investigate the dynamic response characteristics of saturated mudstone under one-dimensional impact load. Under impact with different strain rate, rock samples undergo four deformation stages, including compaction, quasi-elasticity, yielding and unloading. The saturated mudstone has its dynamic elastic modulus in a linear relationship with the strain rate. As the strain rate increases, dynamic fragmentation of the rock samples is significantly enhanced, and the energy dissipation of saturated mudstone also correspondingly increases. The mean error between the peak stress obtained from the numerical simulation and the experiment is 7.9%, which accurately reflects the dynamic characteristics, such as morphology of mudstone fragmentation and dynamic stress-strain relationship, under impact with different strain rates. The strain rate effect of mudstone indicates that blasting disturbance will continuously change its energy state, so dynamic monitoring should be strengthened for the deformation of surrounding rock during tunneling.

Based on the causes of historical dam failure accidents in tailings ponds, a safety grade evaluation index system was built for tailings ponds. The correlation between safety evaluation indexes was demonstrated with Pearson correlation analysis method. An in-depth analysis was conducted for the distribution of sample data to confirm that the sample data met the requirements of the Kriging method for data distribution. Then, the weight of each safety evaluation index was calculated with entropy weight method. The two safety evaluation indexes with higher sensitivity were selected as the X-axis and Y-axis of the Kriging geostatistical model. A geostatistical model was established by using the Kriging method and was verified with empirical case data. The results show that the predicted safety grades of 12 groups of tailings pond data with known safety grades in the geostatistical model are completely consistent with the actual safety grades, which verifies the feasibility and high accuracy of this method.

The effect of ultrasonic melt processing time on the microstructures and hardness of as-cast and homogenized Al-Cu-Mg-Ag-Fe-Ni alloys was studied. The results show that ultrasonic melt processing leads to more uniform distribution of Fe/Ni-rich phases. Two-minute ultrasonic processing can result in grain refinement of the alloy. However, ultrasonic processing, if extended to 6 minutes, will result in grain coarsening. It is found that ultrasonic processing promotes the dissolution of Al₂Cu phase and enhances the solid-solution strengthening effect, resulting in improvement in hardness of the as-cast alloy. After homogenization, Fe/Ni-rich phase is detected as the residual secondary phase in the structure, which exhibits discontinuous distribution along the grain boundaries after ultrasonic processing.

In order to explore the stability and durable service of a blend of construction waste and red clay under load, a California Bearing Ratio (CBR) test, rebound modulus test and failure strength test were performed to determine the appropriate content of red clay in the blend. The influence of compaction degree, confining pressure, stress ratio and loading times on the macroscopic permanent deformation of the blend was comprehensively analyzed by triaxial tests, and the evolution of internal structure during the deformation process of the blend was simulated by discrete element method. The results show that with red clay at an appropriate content of 65%, the blend of construction waste and red clay can have its permanent deformation increase gradually as the stress level becomes higher, and decrease gradually with the increase of confining pressure and compaction degree. During the deformation process, the internal shear stress, coordination number and slip rate of the blend all increase gradually as the stress level becomes higher. Based on the test results and in consideration of stress state, including confining pressure, failure strength and loading stress, physical state, such as compaction degree, and loading times, a permanent deformation prediction model was proposed and validated. With a correlation coefficient of 0.89, the model is considered to have a “relatively good fit”.