Collophanite ore was taken in a test to explore the influence of fine particle entrainment content in return sand to grinding on grinding efficiency. It is found that the lower the fine particle entrainment content in return sand, the higher yield of the newly generated particles in the size range of -0.074 mm. Nevertheless, the increase in the yield of particles within the range of -0.025 mm has little to do with the entrainment content in return sand.

Aiming at problems including low content of magnetic iron, fine dissemination size and high content of ferrous silicate in processing of the amphibole-type primary ore in Yuanjiacun Iron Mine, an experimental study was carried out by adopting a pre-concentration process consisting of fine crushing plus dry magnetic pulley separation and a roll grinding plus wet magnetic separation. The pre-enriched concentrate was then processed with a flowsheet including a three-stage grinding, a three-stage low-intensity magnetic separation and a reverse flotation, resulting in an iron concentrate grading 65.66% TFe at 49.31% recovery, with the yield of 21.45%. It is shown that iron resource can be utilized efficiently.

Mo (VI) and Cu (II) in aqueous solution were extracted by using an aqueous two-phase system consisting of isodecanol polyoxyethylene ether (E-1006) and ammonium sulfate ((NH₄)₂SO₄) for the first time, and a phase diagram of the system was also obtained. Effects of initial pH of aqueous phase, temperature of system, and concentrations of E-1006 and (NH₄)₂SO₄ on Mo-Cu separation effect were also investigated. The results show that with pH of 2.0, temperature of 313.15 K, and both E-1006 and (NH₄)₂SO₄ at concentration of 150 g/L, the extraction efficiency of Mo (VI) is 96.08% and the separation factor for Mo (VI) and Cu (II) is 5 131.45.

Illite, a kind of clay mineral, was taken as an adsorbent in an experiment for low-concentration rare earth ions in rare earth leaching solution to explore effects of initial concentration of Y³⁺, adsorption temperature, pH value of solution, ion concentration, and adsorption time on the adsorption behavior of illite. Then, based on the constructed isotherm model for adsorption of yttrium ions by illite and its reaction kinetic model, the mechanism for the adsorption of yttrium ion by illite was analyzed. Results show that illite has an excellent adsorption performance for Y³⁺. With an increased initial concentration, higher temperature, prolonged time, and higher pH value of solution, the adsorption capacity of Y³⁺ for illite increases. It is found that the existence of Na⁺, Mg²⁺ and Al³⁺ can inhibit the adsorption of Y³⁺ by illite in the following descending order of importance: Al³⁺>Mg²⁺>Na⁺. The adsorption reaction follows Langnuir isotherm model and pseudo-second-order reaction kinetic model. Ion exchange reaction takes place during the adsorption process, thus this adsorption process belongs to chemical adsorption, with adsorption rate controlled by chemical reaction.

According to the characteristics of high-content aluminum and low-content lithium in hydrochloric acid leaching solution of a clay-type lithium ore in Hubei Province, lithium and aluminum were firstly separated by adopting calcination at 390 ℃ for 2.0 h. Then, the calcined residue, without grinding, was leached at 90 ℃ for 1 h with water in a volume ratio of 3∶1. After the leaching process, the leaching rate of lithium reached 93.85%, and no aluminum was detected in leaching solution, indicating a good Li-Al separation result. An analysis of chemical composition of calcined residue and leaching residue show that after water leaching, the main metal elements in the calcined residue, such as lithium, kalium, sodium, calcium and magnesium, all are leached into the lixivium, and the main composition of leaching residue are alumina and iron oxide.

An experimental research was carried out on leaching of marine sedimentary manganese deposit from Xinjiang, and effects of acid-to-ore ratio, leaching temperature, leaching time, and ore particle size on manganese leaching rate were investigated. The results indicate that effective separation between elements of silicon and manganese in the solution can be actualized by increasing leaching temperature and prolonging leaching time, which can also benefit the formation of large-particle precipitates and enhancement of filtering speed. After manganese ores with particle size of -150 μm are leached at room temperature for 4 hours, with acid-to-ore ratio of 0.56, the manganese leaching rate can be up to 86.32% and a leaching residue rate is 61.12%, while the mass concentration of manganese ions in the manganese sulfate leachate is 41.29 g/L.

Based on the investigation of occurrence state, fluoride associated with barite was leached with HCl-AlCl₃ by using Plackett-Burman design, and influences of HCl concentration, AlCl₃ concentration, reaction temperature, reaction time, and liquid-to-solid ratio on fluorine leaching rate were investigated. It is found that the fluorine in barite mainly exists in the form of disseminated and banded fluorite. By using HCl at a concentration of 3 mol/L and AlCl₃ at a concentration of 0.4 mol/L, after 30 min leaching reaction of ore sample with grain size of 48-75 μm, liquid-to-solid ratio of 10 mL/g, and stirring speed at 300 r/min, the leaching rate of fluorine can reach 93.20%, and the mass fraction of barite is 95.91%. Results show that all factors that influence fluorine leaching rate are arranged in descending order of importance as follows: reaction temperature > HCl concentration > reaction time > AlCl₃ concentration > liquidto-solid ratio.

Ginkgo biloba biochar-based fertilizer prepared with Ginkgo biloba was used for remediation of heavy metal contaminated soil. After 4 d remediation at 30 ℃ by adding 4% ginkgo biloba biochar-based fertilizer, the stabilization efficiencies of Pb, Cd, and Cu can reach 89.5%, 97.5%, and 74.9%, respectively. It is shown that the contents of acid extractable Pb, Cd and Cu decrease from 43.81%, 60.53% and 65.31% to 12.21%, 52.75% and 60.47% respectively; the contents of reducible Pb and Cd decrease from 11.12% and 36.35% to 10.02% and 33.71% respectively; the contents of oxidizable Pb and Cd decrease from 14.36% and 0.76% to 11.61% and 0.74%, respectively, while the content of oxidizable Cu increases from 11.13% to 14.12%; the contents of residual Pb, Cd, and Cu increase from 30.71%, 2.36%, and 22.33% to 66.16%, 12.80%, and 24.19%, respectively. It is concluded that with strong stability and a good remediation effect at low cost, such ginkgo biloba biochar-based fertilizer shows a good application prospect in remediation of heavy metal contaminated soil.

Manganese-rich phase with low impurity content was prepared with manganese sulfate crude solution by precipitation. A single-factor experiment was carried out to explore effects of reaction time, reaction temperature, pH value and feeding speed of precipitating agent on precipitation efficiency, and then the content of impurity in the finally prepared manganese-rich phase was also analyzed. After the leaching solution with Mn²⁺ in mass concentration of 38 g/L, and pH of 8.0 was precipitated at 60 ℃ for 4 h, with R as precipitating agent fed at a speed of 0.5 L/h, the conversion rate of Mn²⁺ was 94.3%. The ICP and EDS analyses showed that there were low content of impurity ions (K, Na, Ca, Mg) in the precipitate of manganese-rich phase.

The occurrence state of key elements of niobium, rare earths, and titanium in Bayan Obo niobium concentrate samples was characterized before and after hydrogen reduction, and effect of hydrogen reduction condition on iron metallization rate was also explored. After 90 min reduction with flow rate of hydrogen at 300 mL/min, and reduction temperatures of 800 ℃, 850 ℃, 900 ℃, 950 ℃, 1 000 ℃, and 1 050 ℃ respectively, the corresponding metallization rates are 89.22%, 85.79%, 82.50%, 80.52%, 72.15%, and 70.64%. It is found that during hydrogen reduction process, most of iron minerals can be reduced to metallic iron, but with temperature rise, the reduction rate of iron minerals decreases due to effect of mineral powder bonding. Niobite, as the main niobium-containing phase, is easily reduced, while aeschynite and niobium-iron rutile are difficult to be reduced; bastnasite, the main rare earth-containing phase, doesn't change, while monazite can undergo thermal decomposition at 1 050 ℃; ilmenite, niobium-iron rutile and aeschynite, as the main titanium-containing phases, are difficult to be reduced.