With the polymetallic tailings from Chenzhou of Hunan Province as the research object, an approach of macro volume and mass separation according to the composition of tailings was proposed for a comprehensive utilization. Firstly, magnetic separation was used to sort out iron-aluminum minerals, and then the non-magnetic minerals were processed to obtain calcium and silicon minerals by adopting a flotation process consisting of one stage of roughing, two stages of scavenging and seven stages of cleaning, with sodium oleate as the collector, sodium carbonate as the regulator, and the mixture of GLY-Ⅲ and sodium hexametaphosphate as the depressant. The as-obtained iron-aluminum minerals contain 40.17% garnet at a recovery of 94.08%. The obtained calcium mineral has a Ca grade of 58.00% at a recovery of 50.29%, with the content of fluorite therein reaching 76.47%, while the silicon mineral has a Si grade of 27.96% at a recovery exceeding 99%. These three products all meet the requirements for preparing building materials such as cementing materials and ceramic aggregates, providing new methods and ideas for high consumption of tailings.

To effectively recover titanium resources in the tailings from a titanium processing plant and improve the relative utilization rate of raw ore, beneficiation of the tailings with a TiO₂ grade of 5.81% from the tailings pond was studied. A gravity and magnetic separation process were proposed and the influences of magnetic field intensity, rising water flow rate, feeding rate and feeding concentration on ilmenite separation indices were studied. The results show that after a gravity separation of +38 μm range, a gravity separation of underflow from -38 μm classification and magnetic separation of overflow from -38 μm classification, a rough concentrate with TiO₂ grade of 16.08% was obtained at recovery of 62.63%, while tailings with a yield of 77.41% and TiO₂ grade of 2.39% was cast off. Consequently, the feeding amount of succeeding flotation can be greatly reduced.

In order to clarify the influence of geometric parameters of tapered pipeline on particle flow characteristics in pneumatic conveying, numerical simulation was conducted for horizontal pipelines with 5 kinds of taper ratio and taper length by adopting CFD-DEM coupling method. Influence of geometric parameters of taper ratio and taper length on particle velocity, pressure loss and Froude number in tapered pipeline was investigated. The results show that tapered pipe can reduce particle velocity. As taper length and taper ratio increase, particle velocity increases first and then decreases. And the tapered pipe can also reduce pressure drop in pipeline. As taper ratio and taper length increase, pressure loss in pipeline increases. The higher the taper ratio, the smaller the Froude number in tapered pipe is. As taper length increases, the Froude number decreases more slowly.

Experimental study was conducted on the properties and beneficiability of a refractory scheelite ore from Luanchuan of Henan Province. The results show that the WO₃ grade for this diopsidite garnet skarn-type molybdenum-tungsten ore is 0.067 2%, and scheelite is the dominant tungsten minerals. This ore is prone to become sliming and also has high content of calcium-bearing gangues, which are unfavorable to scheelite recovery. With a flotation reagents scheme including regulator sodium carbonate 1 500 g/t, depressor sodium silicate 600 g/t, depressor SG 40 g/t, and collector FX-6 400 g/t, a closed-circuit test was performed with the tailings from molybdenum flotation for scheelite flotation. As a result, the roughing stage in the closed-circuit test produced a rough scheelite concentrate grading 1.472% WO₃ at 83.54% recovery, and the cleaning stage produced a scheelite concentrate grading 31.92% at 95.71% recovery. By using a combination of sodium silicate and SG, the recovery efficiency of scheelite can be effectively improved, which is favorable for subsequent large-scale industrial production.

In order to obtain the optimal concentration of bone glue as a commonly used additive for lead electrolysis and also understand the influence of its colloidal impurities on lead electrolysis, the effects of the concentration of bone glue in the electrolyte, the standing time of bone glue solution and the liquid-solid ratio for purification with activated carbon on lead electrolysis were investigated by evaluating the turbidity of the solution, current efficiency, power consumption and the morphology of precipitated lead. It is found that the optimal concentration of bone glue in lead electrolyte is 0.8 g/L, and colloidal impurities can be removed by resting the bone glue solution for 72 hours or by purifying it with activated carbon in a ratio of 1 000∶1. After purification, lead electrolyte has its current efficiency up to 99.19%. The power consumption of electrolysis declines to 51.79 kW·h/t, and the obtained precipitated lead has a flat and smooth surface.

Experiments were carried out for alumina ceramics with rotary ultrasonic-assisted and ordinary milling-grinding processes respectively by using a small diameter electroplated grinding wheel. The variation of grinding force with ultrasonic power, linear speed of grinding wheel, feed rate and grinding depth during milling-grinding of alumina ceramics was analyzed. The results show that with ultrasonic power from 0 W up to 90 W and other parameters keeping constant, the grinding force is in decline and the surface topography is significantly improved. As the linear speed of grinding wheel increases, while the feed rate and grinding depth decrease, the grinding force in both rotary ultrasonic-assisted and ordinary milling-grinding processes decreases. With the processing parameters in the tested range, the grinding force in rotary ultrasonic-assisted milling-grinding process is lower compared to the ordinary milling-grinding process. Besides, the maximum reduction in normal and tangential grinding force of rotary ultrasonic-assisted milling and grinding can reach 24.17% and 23.30% respectively.

According to the difficulties in beneficiation, such as intimate dissemination and complicated intergrowth of pentlandite, chalcopyrite and pyrrhotite, and high content of magnesium-bearing silicate minerals, a beneficiation experiment was conducted for a low-grade copper-nickel sulfide ore from abroad. A flowsheet consisting of rough grinding, fine-grinding of middlings, copper-nickel bulk flotation was introduced to treat this raw ore with Ni and Cu grades respectively as 0.50% and 0.20%. Adopting selective grinding approach and using high-efficient depressant CMC, excessive comminution of copper and nickel minerals can be avoided while magnesium-bearing silicate minerals can be selectively depressed. A closed-circuit test produced a copper-nickel concentrate grading 9.70% Ni and 4.75% Cu at corresponding recoveries of 68.99% and 79.85%, indicating copper and nickel resources were all effectively recovered.

Effects of Ca²⁺, Mg²⁺, SO₄^2- and PO₄^3- on the flotation behavior and surface properties of dolomite and fluorapatite were studied by performing tests of pure mineral flotation, Zeta potential and contact angle. The results show that dissolved ions can significantly change the floatability, surface electricity property and surface wettability of these two minerals. Ca²⁺, Mg²⁺, SO₄^2- and PO₄^3- can reduce their contact angles, weaken their hydrophobicity and decrease the flotation recovery. Ca²⁺ and Mg²⁺ can increase, while SO₄^2- and PO₄^3- can decrease the Zeta potential of dolomite and fluorapatite. These results can be used as reference for removal of harmful ions in phosphorite ore processing.

In order to improve the working performance of drum cutter in mining mechanism, the cutting process of drum cutter under different working conditions was numerically simulated by using discrete element method (DEM). The effects of cutting thickness, rotating speed and tractor speed on cutting resistance, productivity and specific energy consumption were investigated by single-factor analysis and orthogonal testing. With cutting resistance and specific energy consumption of the drum cutter as evaluation indexes, the best working parameters of the drum cutter were obtained by matrix analysis. The results show that as cutting thickness increases, both cutting resistance and productivity increase, while specific energy consumption decreases. With rotation speed increases, cutting resistance and productivity decrease, but specific energy consumption increases. And with tractor speed increases, both cutting resistance and productivity increase, while specific energy consumption decreases. It is concluded that the optimum working parameters of drum cutter are as follows: cutting thickness of 50 mm, rotation speed of 100 r/min, and tractor speed of 0.06 m/s.

Mineral processing tests were conducted for a fine refractory copper ore with Cu grade of 0.75%. A combined process consisting of magnetic separation, rapid flotation of copper minerals, enhanced copper flotation of rapid flotation tailings, and regrinding and cleaning of rough copper concentrate was adopted in a closed-circuit test, yielding a copper concentrate grading of 23.57% Cu at a recovery of 83.23%.