In order to find a reasonable disposal method for electrolytic manganese slag (EMS), effect of roasting at medium and high temperature on the content of manganese, sulfur and ammoniacal nitrogen in EMS was explored. The results show that after the EMS is directly roasted at 1 050 ℃ for 60 min, the mass fraction of S in the EMS sample falls from 9.11% to 0.87%, while the mass fraction of Mn goes up from 1.87% to 2.26%. After being washed with water, the EMS sample is then roasted with 3% coal (in mass fraction) at 1 000 ℃ for 60 min. As a result, the mass fractions of S and Mn in the obtained roasted sample drop down to 1.32% and 0.78%, respectively. It is found that after direct roasting process at medium and high temperature, EMS can meet the requirement of mass fraction of S for cement admixture, and also medium and high temperature roasting process can almost remove all ammoniacal nitrogen therein, presenting a good removal effect.

In order to improve the strength-ductility balance of medium manganese steel for automobiles, cold-rolled medium manganese steel was treated by annealing at different temperatures (650-680 ℃) and for different time (10-50 min) for austenitic reverse transformation. Then, effects of annealing temperature and holding time on the microstructure and mechanical properties of medium manganese steel were explored. It is found that the microstructure of the original cold-rolled medium manganese steel plate is composed of ferrite (F) and martensite (M), and the dispersed carbides with sizes ranging from 20 nm to 45 nm can be observed in the microstructure. As the annealing temperature rises from 650 ℃ to 680 ℃, the yield strength, elongation, strength-ductility balance, and residual austenite volume fraction of medium manganese steel increase followed by a decrease, but tensile strength increases all the time. As the annealing time is prolonged from 10 min to 50 min, the yield strength, tensile strength, elongation, strength-ductility balance and residual austenite volume fraction of medium manganese steel decrease after an initial increase. It is found that after annealing treatment at 660 ℃ for 30 min, the cold-rolled medium manganese steel has a structure composed of F + M + austenite (γ), with austenite at a volume fraction of 24.12%, ultrafine grained ferrite with an average grain size of 0.29 μm, lath martensite with an average wideness of 0.27 μm, and strength-ductility balance of 23.33 GPa·%.

Nickel, Cobalt and Manganese in the cathode materials of spent ternary lithium-ion batteries were recovered by leaching with a combination of citric acid and hydrogen peroxide. The possible reactions during the leaching process were analyzed, and the effects of factors, including citric acid concentration, mass fraction of hydrogen peroxide, leaching temperature, leaching time and liquid-to-solid ratio on the leaching rates of nickel, cobalt and manganese from cathode materials were also investigated. It is found that after 60 min leaching at 80 ℃ with citric acid at a concentration of 1.5 mol/L, hydrogen peroxide at a mass fraction of 8%, and a liquid-to-solid ratio of 25 mL/g, the leaching rates of nickel, cobalt and manganese are 97.58%, 97.35% and 96.12%, respectively. Then, an antisolvent crystallization method is adopted with ethanol as antisolvent agent to recover metals from the obtained leach liquor, leading to the crystallization rates of nickel, cobalt and manganese at 92.34%, 93.07% and 99.69%, respectively.

An experiment study was carried out on a processing technique of reduction leaching of pyrolusite with acidic wastewater from steel mills as the reductant, for comprehensive utilization of pyrolusite and acidic wastewater of steel mills. The results show that 3 hours of leaching at 90 ℃, with FeCl₂ and MnO₂ in a mass ratio of 2.2, liquid-solid ratio of 11∶1 and the acid wastewater at an initial concentration of 2.5 mol/L, can result in the leaching rates of Mn, Fe and Al from the pyrolusite at 97.14%, 95.37% and 41.33%, respectively. And then, Fe³⁺ in the leachate is reduced with scrap iron at an amount of 1.1 times the theoretical amount at a temperature of 80 ℃ for 50 min, leading to the reduction rate of Fe³⁺ up to 99.85%. After Fe³⁺ is reduced to Fe²⁺, the Fe²⁺-containing reducing solution is returned for leaching again, presenting stable leaching results. It is shown that the average leaching rates of Mn, Fe and Al from pyrolusite are 96.75%, 95.31% and 41.18%, respectively.

In order to investigate the main factors affecting the service life of graphite anodes used in preparation of rare earth metals, a range of analytical tools, including a digital microscope, an optical microscope, an SEM, XRD, a simultaneous thermal analyzer and a four-probe tester were employed for comparison and comprehensive evaluation of macroscopic and microscopic morphology, crystal structure, graphitization, thermal properties and resistances of graphite anodes with different service lives. The results indicate that the resistance, internal cracks and porosity of graphite anodes contribute mainly to the difference in the service life of graphite anodes. The research results can be of reference for selection of graphite anode in preparation of rare earth metals, thus providing technical assistance for enterprises to realize cost reduction and efficiency improvement.

In order to balance productivity against safety in the mining of high-level stope with gently-dipping and extrathick orebody, an iron mine adopting sublevel open stoping with backfill was taken as an example to optimize the mining sequence. Firstly, pillars was determined to at a reasonable spacing from 14.2 m to 47.2 m based on the theory of bearing capacity of pillars. Secondly, according to stope structure parameters, the pillars were designed to be 15 m, 30 m and 45 m in thickness, respectively. An orebody model was also established with FLAC^3D and then was used to analyze the roof subsidence and pillar stability based on comparison of each mining scheme. Finally, a judgment matrix of mining sequence was constructed based on analytic hierarchy process and fuzzy comprehensive evaluation method, with both factors of safety and productivity taken into consideration in the numerical simulation. The comprehensive membership degrees of those three schemes were calculated to be 0.86, 0.79 and 0.80, respectively, and pillars in the best scheme were determined to be in the thickness of 15 m. The results of an industrial experiment have proven that this scheme can ensure stope with relative stability while achieving the maximum production capacity.

An iron concentrate obtained from magnetic separation of red mud from Shandong was used in an experimental study on the effect of titanium removal by reverse flotation. In the experiment, with sodium oleate as collector, corn starch as hematite depressant, sulfuric acid as pH regulator, pulp pH of 9, and the addition of corn starch and sodium oleate at an amount of 500 g/t and 1 500 g/t, respectively, the iron concentrate was produced, with the TiO₂ grade fell down from 6.90% to 2.73%, and the TFe recovery reaching 41.80%. The results of collector adsorption and IR analysis show that sodium oleate exhibits selective adsorption characteristics, which has further confirmed the feasibility of sodium oleate used in removing titanium by reverse flotation of iron concentrate obtained from magnetic separation of red mud.

Vanadium was extracted from vanadium-containing stone coal by adopting a process of sulphuric acid curing and water leaching, and the effects of sulphuric acid curing and water leaching conditions on vanadium leaching rate were investigated. It is found that the vanadium-containing stone coal is firstly subjected to a sulphuric acid curing process at 130 ℃ for 8 h, with an addition of H₂SO₄ at an amount of 25%；and then the obtained product is leached by water at 90 ℃ for 120 min, with liquid-solid ratio of 2∶1, resulting in the vanadium leaching rate of 90.79%. After the vanadium-containing leachate is oxidized with NaClO₃, the vanadium in the oxidized solution is adsorbed with D202, and then the vanadium in the resin is desorbed. The obtained solution after desorption is subjected to calcination, and vanadium pentoxide is produced with a purity up to 99.21%. It is shown that a total recovery rate of vanadium is 85.99%.

A cyanide-free leaching test was performed for the arsenic-carbon bearing gold ore from Laos, and effects of grinding fineness, pH value of pulp, concentration of slurry, and the dosage of golden cicadas environment-friendly leaching agent for gold on gold leaching effect were investigated. The results show that pre-treatment with hydrogen peroxide can improve the leaching rate of gold. With a grinding fineness of -0.074 mm 95% and an agitating speed of 2 000 r/min, the pulp is pre-oxidized with 500 g/t of hydrogen peroxide for 3 h, and then treated by 30 h agitation leaching with addition of lime at an amount of 3 000 g/t and golden cicadas environment-friendly leaching agent for gold at 5 000 g/t, leading to the residue grading 0.25 g/t Au and gold leaching rate of 92.27%. It is shown that this pretreatment with hydrogen peroxide can make gold leaching rate up by 1.96 percentage points.

In order to utilize low-grade associated cassiterite resource from Huangshaping polymetallic ores, a new beneficiation process consisting of high-gradient magnetic separation (HGMS) for tailings discarding and tungsten-tin flotation for enhanced enrichment was developed based on the performed HGMS and flotation tests. After HGMS to pre-discard tailings, the loss rates of molybdenum, tungsten and fluorite were all less than 10%, while cassiterite was greatly enriched in the HGMS rough concentrates. Then, a flotation of reground HGMS rough concentrate was conducted by using Pb-BHA-SPA multiple ligand metal-based collector, producing a mixed tungsten-tin concentrate grading 0.627% WO₃ and 0.78% SnO₂, at corresponding recovery of 26.56% and 18.03%, respectively. This process provides a new idea and method for enhanced enrichment and effective utilization of low-grade associated cassiterite.