SAG mill grinding and conventional crushing-grinding processes adopted in Baima Iron Mine are introduced. Based on the detailed comparison of processing flowsheet, production index, equipment operation parameter, construction investment, operation cost, it can be concluded that the SAG milling process has the advantages of simple process, low construction investment, good adaptability to ores and fine grinding fineness, also some disadvantages like high equipment failure rate, short service life for lining plate, relatively low equipment operation rate and high production cost. These results can be referred in the construction of similar mines.

Based on the experience from production practices, an orthogonal experiment was performed by simulating a grate-rotary kiln process to investigate factors affecting compressive strength of preheated pellets and also find measures to improve the process. It is found that both OA iron ore and OB iron ore are fine-grained, with -0.074 mm grain content greater than 85%, which meets the basic requirements for particle size in pelletizing process. With 90% OA iron ore blended with 10% OB iron ore, the obtained pellet after drying and preheating process can have FeO content reduced from 26% to less than 4%, with the oxidation degree greater than 85%. With the following optimal thermal parameters of chain grate, including a drying temperature of 200 ℃ for air blowing and a drying temperature of 360 ℃ for ventilation, 720 ℃ for I-stage preheating and 990 ℃ for II-stage preheating, the obtained preheated pellet can have a compressive strength of 1 056 N/pellet. It is verified that the experimental result is in accordance with the anticipation.

Fluoride-containing industrial wastewater was treated by using a composite coagulant of polymerized aluminum chloride (PAC) and polyacrylamide (PAM), and effects of PAC dosage, PAM concentration, pH value, reaction time and stirring speed on fluoride removal efficiency were explored. The results show that by adding 4 400 mg/L PAC, with PAM concentration of 1 mg/L, solution with pH of 7.0, reaction time of 20 min and stirring speed of 300 r/min, the fluoride removal rate can reach 97.98%, leading to the residual concentration of fluoride ion at only 0.81 mg/L. However, the presence of impurity ions can reduce the fluoride removal rate by PAC.

A slope of ionic rare earth mine was taken to study the variation of pore water pressure in the slope during and after rainfall events with different rainfall intensity, and the varied critical slip surface during these two periods of time was also studied by using the finite element Morge nstern-Price method. The results show that the rainfall intensity is a significant factor affecting the pore water pressure of shallow slope of ionic rare earth mine. The hysteresis property of rainwater infiltration into the slope is the internal reason for hidden risk of potential slope instability after rainfall events. The greater rainfall intensity will lead to faster formation of the 289 slip surface, higher peak value of greatly changed safety factor, as well as longer influence time. It is proposed for the first time that the development of ionic rare earth mine slope under rainfall conditions may experience four stages: safety, drastic internal variation, high landslide susceptibility, and relative safety.

The effect of Cr content on microstructure and heat exposure of Al-Cu-Mg-Ag alloys was investigated. It is found that strength of the alloys at room temperature decreases after an initial increase as Cr content increases, and the 0.2%Cr alloy exhibits excellent room-temperature mechanical properties. Transmission quantitative calculation results suggest that an addition of 0.2%Cr can promote precipitation of Ω phase and improve coarsening resistance of Ω phase in the alloy after heat exposure. With the addition of Cr exceeding 0.3%, the (Al, Cr, Mn, Ti)-enriched phases precipitate at the grain boundaries of the alloy, leading to coarser grains.

Experimental study was carried out on continuous leaching of mixed wolframite-scheelite concentrate with soda in a horizontal continuous autoclave reactor, and the effects of various processing parameters on the decomposition rate of the mixed ore were investigated. Under the processing conditions, including grinding fineness of -0.050 mm for the mixed ore, leaching temperature of 200 ℃, liquid-to-solid ratio of 2.1∶1, soda usage at four times of the theoretical dosage, addition of NaOH at 25 kg/t of ore, and feeding rate of 10 m³/h, the decomposition rate of tungsten in the mixed wolframite-scheelite concentrate reaches 99.55%, with only WO₃ content of 0.28% in the slag. It is found that the continuous leaching with soda offers the advantages of easy operation, higher production efficiency, lower energy consumption, stable decomposition rate, as well as higher automation.

With a tailings pond in Lesser Khingan Mountains region as an example, experiments were carried out on tailings embankment respectively by upstream construction with discharged wet metallic tailings, by filling a pond with metallic tailings, and by construction with overflow and underflow of tailings separately from cyclone. It is shown that the embankment construction with overflow and underflow separately from cyclone is superior over other two methods based on comparison. It can not only effectively improve consolidation of the tailings in front of the embankment through drainage, prolong the length of dry beach and increase the strength of the tailings in front of the embankment, but also create a wide sloping sediment, keep the embankment within the freeboard, improve the seepage condition of the dam body, as well as increase the bearing capacity of beach surface and the efficiency of embankment construction. By improving the cycloning process, a scheme including constructing embankment during non-winter seasons and discharging tailings in winter to build a wide sub-dam is proposed, which can solve the previously existing problems to a certain extent, such as sediment beach with high water content and low bearing capacity, as well as inability to build sub-dam with tailings sand. However, both the utilizing rate of coarse sand, the width of sub-dam of high-grade tailings pond and development of frozen soil still need to improve. Finally, it is found that the embankment construction by adopting technique of building wider sub-dam with underflow and overflow of tailings from cyclone combined with geofariform method can effectively resolve the existing problems for tailings dam. Thus, this technique can be promoted as an effective embankment construction scheme with fine-grained tailings in regions with high altitude and cold weather.

Experimental study was carried out to realize comprehensive recovery of non-metallic mineral resources from granite tailings in Henan Province, and explore the feasibility of preparing high-purity quartz. The results show that the granite tailings, mainly containing minerals of plagioclase feldspar, quartz, potassium feldspar and mica, have potential to be comprehensively utilized. With a flowsheet consisting sequentially of scrubbing-magnetic separation, pre-treatment of desliming, and mica-feldspar-quartz preferential flotation, a mica concentrate with Al₂O₃, K₂O, Na₂O, SiO₂ and Fe₂O₃ contents of 33.84%, 8.13%, 0.32%, 56.78% and 0.121%, a feldspar concentrate with Al₂O₃, K₂O, Na₂O, SiO₂ and Fe₂O₃ contents of 15.89%, 2.16%, 10.68%, 71.06% and 0.124%, and a quartz concentrate with Al₂O₃, K₂O, Na₂O, SiO₂ and Fe₂O₃ contents of 1.05%, 0.17%, 0.56%, 97.76% and 0.106%, respectively, can be collected. The quartz concentrate can be further purified to obtain a high-purity quartz sand with SiO₂ content of 99.994%.

Aiming at the shortcomings of single crystalline high-nickel ternary cathode material, including high residual alkali on the surface, poor cycle performance at high temperature, co-doping with niobium and yttrium was proposed to modify the cathode material for improving its electrochemical performance. With monocrystalline high-nickel ternary precursor (Ni_0.6Co_0.1Mn_0.3(OH)₂) as raw material, a series of cathode materials co-doped with two different elements were synthesized by high-temperature solid-state reaction. The results show that the niobium and yttrium co-doped sample presents excellent cycling stability and rate capability at high temperature. Compared to niobium-doped sample, it can have capacity retention rate higher by 2.58 percentage points after 50 cycles at 45 ℃, and discharge capacity higher by 6.2 mAh/g at 2C charge-discharge rate.

The effect of hydroxamic acids on flotation of fluorapatite and dolomite was studied. The flotation results show that salicylhydroxamic acid exhibits certain selectivity but low recovery for fluorapatite and dolomite; octylhydroxamic acid shows poor selectivity but high recovery for fluorapatite and dolomite; while benzohydroxamic acid possesses high selectivity and recovery for fluorapatite. The flotation mechanism of fluorapatite and dolomite in the presence of benzohydroxamic acid was studied by performing zeta potential measurement, adsorption capacity test and XPS analysis. It is found that benzohydroxamic acid is an ideal collector for fluorapatite and dolomite.