A technique of nanofiltration combined with ammonium sulfide precipitation was verified for its feasibility of separating and recovering ammonium nitrate and nickel nitrate from nickel-containing feed solution. Based on investigating the effects of pressure on the side of concentrate stream in nanofiltration, stages of nanofiltration and pH value of ammonium sulfide precipitate, an appropriate route was determined, including two-stage nanofiltration, KLNi-01 ion exchange to remove nickel, nickel precipitation with ammonium sulfide, and dissolution with nitric acid to recover nickel nitrate. The feed stream with pH of 6 was subjected to a two-stage nanofiltration, with pressure of 0.8 MPa on the side of concentrate stream. The obtained permeate stream with nickel content decreased to 0.181 g/L was adsorbed with KLNi-01 resin, leading to the nickel content therein further reduced to 0.002 mg/L. Then, 36 mL/L ammonium sulfide solution was added into the concentrate stream with an initial pH of 6 for nickel precipitation. The generated solution had nickel content of 4.7 mg/L, and no sulfide was detected, while the obtained precipitate of nickel sulfide was then dissolved with nitric acid, and the nickel nitrate solution was obtained with concentration of 258.40 g/L. The material balance calculation shows that treatment of 1 m³ of nickel-containing feed stream can generate 0.3 m³ permeate, and 192.93 L of nickel nitrate solution with concentration of 258.40 g/L can be generated with the consumption of 25.20 L of ammonium sulfide solution with concentration of 20%-26%, 37.22 L of concentrated nitric acid and 109.05 L of water.

With micro-nano TiC as reinforcing phase and nickel powder as matrix powder, a TiC reinforced Ni-based coating was fabricated by laser cladding technology, and the effect of TiC on microstructure and wear resistance of the coating was investigated. The results show that Ni-based coating has its microstructure predominately composed of γ-Ni and TiC, and a high content of TiC is prone to cause TiC segregation at the top of coating. With the increase of TiC content, coating will have its hardness increase gradually, especially have an obvious improvement in the surface hardness. A three-body wear test shows that the wear resistance of this composite coating decreases as TiC content increases, indicating that the brittle reinforcement phase is not conducive to improving wear resistance of the coating under impact load.

A medium-low grade calcium-magnesium phosphate ore was ground to a fineness of 56.74% -0.075 mm and was used to study the liberation characteristics of particle size within varied ranges on its flotation behavior. The particles were classified into coarse ranges (+0.15 mm, -0.15+0.106 mm and -0.106+0.075 mm) and fine ranges (-0.075+0.038 mm and -0.038 mm). The content of different minerals in each size range was estimated by using X-ray fluorescence spectroscopy and X-ray powder diffraction analysis, while the intergrowth and monomer liberation was evaluated with the backscattering images obtained from scanning electron microscopy. It is found that the content of liberated minerals increases as the particle size decreases. Fluorapatite is primarily enriched in the coarser particles within the size range of +0.075 mm, whereas dolomite is concentrated mainly in fine particles of -0.075 mm. By improving the selective aggregation of valuable minerals and gangues in size range of -0.038 mm, the P₂O₅ loss can be reduced. Furthermore, by reducing the content of coarse particles within the size of +0.075 mm and increasing the content of particles within -0.075+0.038 mm range, both P₂O₅ grade and recovery of the concentrates can be effectively improved.

It is difficult to simulate and analyze distribution of seepage field for the slope at the entrance of excavated tunnel during heavy rainfall. Aiming this problem, a slope project at a tunnel entrance was taken for study, and FISH language in the FLAC^3D was redeveloped to determine the permeability coefficient of soil under different saturation state during rainfall infiltration, and the boundary conditions for rainfall infiltration were updated in real time. In addition, the pore water pressure, matrix suction distribution, as well as safety and stability of the slope at the tunnel entrance after different support schemes were all analyzed with different rainfall durations. The results showed that after 24 hours of heavy rainfall, the slope before and after a combined support including anti-slide piles and anchor cables all reached saturation state, that is, the saturation line ran through from the foot to the crest of the slope, while the slope, after benching and being supported with bolt, had its surface soil from the foot to the secondary platform of the slope under a saturated state. As for the slope at tunnel entrance supported by anti-slide pile combined with anchor cable, the variation law of its safety factor during rainfall was consistent with that of the slope without support treatment, showing that the factor of safety tended to be stable after an initial rapid decrease, and gradually reached 1.2. As for the slope after benching and being support with bolt, its factor of safety decreased a little and maintained above 1.8. It is concluded that the factor of safety, excavated earthwork quantity and total investment for the support scheme should be taken into consideration before starting a slope engineering at a tunnel entrance, and a combined support scheme including anti-slide pile and anchor cable is superior to the scheme including benching and support with bolt.

In order to improve the efficiency of lithium extraction by brine adsorption, a process consisting of pre-concentration and adsorption was developed for lithium extraction. Based on the theory of phase diagram of Na⁺, K⁺//Cl^--H₂O ternary system at 50 ℃ and 100 ℃, variation of lithium concentration and lithium loss rate in brine at different temperatures with different evaporation rate was explored in the test, and the adsorption effects of adsorbents on brine before and after pre-concentration were compared. The results show that the concentration and loss rate of lithium in the solution are not affected by evaporation temperature. As the evaporation rate exceeded 40%, the loss rate of lithium in brine increased rapidly. The pre-concentrated brine with concentration of 55 mg/L lithium at an evaporation rate of 40% was adsorbed with manganese absorbent, showing that the lithium adsorption capacity reached 4.25 mg/g after 4 hours, higher than the adsorption capacity of 3.39 mg/g in the original brine without pre-concentration. It is proven that brine pre-concentration can enhance the adsorption effect of lithium brine extraction.

The impact of blasting vibration on the open-pit slope in a limestone mine was explored. The characteristics and law of blasting vibration was investigated by performing field blasting vibration tests based on the consideration of geological conditions on site. Based on fitting with Sadowski formula, an obvious attenuation trend was found for the velocity of particle vibration in the data about two field blasting vibration. With Sadowski formula modified based on elevation effect, the correlation coefficient was up to 0.94, better than the fitting effect by the traditional Sadowski formula. The maximum vibration velocity on each bench of limestone slope was predicted by using the modified fitting formula in this paper, and considering the designed detonate charge for steep end-slope, showing that the impact of vibration source on the adjacent bench should be taken into consideration in blast design.

With Bayan Obo niobium concentrate and semi-coke powder as raw materials, effect of basicity on melting process of the reduction product of carbon-containing pellets was observed in situ by using a high temperature heat table. The samples with optimum basicity were quenched and prepared at different melting conditions. The migration rule of elements during the melting process was analyzed by SEM-EDS, and the reaction rates of Nb and Si in the melting process were quantitatively analyzed by XRD, TG-DSC and ICP. Results show that with the binary basicity of 1.0, the spattering of molten slag can be effectively suppressed and the melting efficiency can be improved. With the basicity of 1.0 and temperature of 1 350 ℃, the SiO₂ in the slag is reduced at slag-gold interface and pulled into iron phase. After the molten slag is held at 1 400 ℃ for 2 min, the C in molten iron at slag-gold interface is preferentially reacted with the niobium oxide in the slag and reduced to NbC. A small amount of NbC is dissolved into the iron phase, and most of the remaining NbC is wrapped around the granular iron, forming a retention zone, which hinders the mass transfer at the slag-gold interface and reduces the reduction rate. After hot-holding at 1 400 ℃ for 10 min, the reaction rates of Nb and Si are 36% and 1.7% respectively. Titanium and rare earth are not involved in the reaction during the whole melting separation process.

Some typical rock was taken as the sample in an experiment to study the mechanical properties of white sandstone under uniaxial compression with strain rates ranging from 10^-5 s^-1 to 10^-3 s^-1. The surface displacement contours of the samples were observed and collected by using 3D-DIC system, and the difference in the deformation and failure characteristics of samples under the effect of different strain rate was also analyzed. The results show that the variation of displacement field on the surface of rock sample reflects an evolution law of failure surface, and there is a corresponding relationship between shear failure plane and concentrated displacement field. The difference in the overall axial strain mainly occurs during the period from micro-crack compaction to elastic deformation. At an initial stage of loading, there is difference in the overall radial strain. The lower end part of the sample has the largest radial displacement when the strength reaches the peak, while the upper end part is deformed under the impact of the end effect. The radial outward expansion is limited by the friction between the end face and the gasket. In addition, the local axial strain at the lower end is greater than that at the upper end. With an increase in the loading rate, rock sample has its mechanical characteristics converted from ductility to fragility. During the failure process of rock sample under the uniaxial compression with a lower loading rate, the occurred pore collapse results in friction effect due to the closure again and slippage of some cracks, thus there appears fluctuation in the stress-strain curve near the peak strength. It is shown that the mechanical parameters (peak strength, elastic modulus and Poisson's ratio) of white sandstone increase as the loading rate increases.

Research on redox leaching of intermediate of nickel hydroxide with synergetic effect of nickel sulfide was carried out, and optimum leaching conditions were obtained from tests, including intermediates of nickel sulfide and nickel hydroxide in a mass ratio of 1/10, initial acidity of 4 mol/L, temperature of 90 ℃, liquid and solid in a ratio of 2.0, and a reaction time of 5 h. Under such conditions, the leaching rate of manganese from nickel hydroxide can reach 99.88% and the utilization rate of nickel sulfide is also up to 79.50%. And the leaching residue can be returned as a reducing agent in the reduction and leaching of nickel hydroxide. By using this method, the consumption of both the reducing agent in leaching of nickel hydroxide and the oxidizing agent in leaching of nickel sulfide can be greatly reduced. In addition, the leaching of intermediate of nickel hydroxide can be achieved with synergetic effect of nickel sulfide, which is easy to operate and can be applied into industrial production.

A concept of short delay blasting with blastholes in a combined fan pattern was put forward, in which a row of reinforced holes were added between each row of conventional fan-pattern holes, and detonation was initiated with short delay interval between the conventional row of holes and the added row of holes. The blasting scheme with different delay interval, and blastholes loaded with different confining pressure were numerically simulated with ANSYS/LS-DYNA. It is found that blasting crater cannot be effectively produced by adopting the scheme with conventional holes in fan pattern under high geo-stress environment, while the scheme of short delay blasting with holes in combined fan pattern is more effective in obtaining damaged and ruptured rock, showing better rock breakage effect. In addition, analysis of crack propagation under different confining pressure shows that the blasting crack tends to grow in the direction of the maximum principal stress. The numerical simulation and field engineering practice have proven that when there is an acute angle between the maximum principal stress and that added row of blastholes in fan pattern, that is, higher confining pressure is loaded in the direction of the horizontal row of holes, and lower confining pressure is loaded in the direction of the vertical row of holes, the short-delay blasting with blastholes in such a combined fan pattern can not only improve the rock breakage effect, but also effectively keep rear row of blastholes and the rock mass behind not impacted by the blasting.