Biomass was used as reducing agent to roast the Baotou low-grade limonite in a high temperature vacuum atmosphere furnace. The effect of calcination temperature, time and ratio of reducing agent on the magnetic properties of calcined ore was studied by VSM. The phase and microstructure changes of limonite before and after calcination were analyzed by XRD and SEM. The results show that in the roasting process the phase transition process of the ferrous material in limonite is first dehydrated at high temperature to formα-Fe₂O₃, and then it is converted into Fe₃O₄ by the reduction of biomass. With the increase of calcination temperature, the magnetic properties of the calcined ore first increase and then decrease. When the temperature is higher than 650°C, Fe₃O₄ will become Fe₂SiO₄, resulting in reduced the magnetic material in calcined ore and the magnetic weakened. The best magnetization effect was obtained when the roasting temperature is 550°C, the percentage of biomass was 15% and the roasting time was 30min. The saturation magnetization can reach 60.13emu·g^-1, the recovery of iron was 72% and the grade of iron was 58%.

Impurity removal and modification of rare earth concentrate powder were conducted by roasting weak acid-weak alkali leaching to obtain the active components of denitrification catalysts. NH₃ selective catalytic reduction catalyst samples were prepared by mixing and kneading with pseudo-γ-Al₂O₃ boehmite as carrier. The results showed that the Ce₇O₁₂ content in the active component samples increased and dispersed more evenly. The grain size of the samples was refined, the specific surface area increased, and the active sites exposed more. Ce coexists in the form of Ce³⁺ and Ce⁴⁺. Fe coexists in the form of Fe³⁺ and Fe²⁺, but Fe³⁺ is abundant. Some Ce, La, Nd, Pr, Fe, Mn, and other components formed solid melts during preparation, which increased the synergistic catalytic effect. The denitrification efficiency of the catalyst sample was 92.8% under the conditions of reaction temperature 400 °C, NO content was 600 ppm, NH₃/NO ratio was 1.5, and O₂ concentration was 4%.

The adsorption properties of l-cysteine (L-cys) on [Kr] 4d ¹⁻⁴ (Y-Mo) doped graphenes with single and double vacancies are studied using density functional theory calculations with dispersion correction. The results showed that Y, Zr, Nb and Mo doped single-vacancy and double-vacancy graphenes show chemical adsorption characteristics towards L-cys. For the respective S, O and N-end adsorption, the binding strengths of L-cys on XSVs decrease from Y to Nb, and then increase. The binding strengths of L-cys on XDVs have no regular trend. Nb-doped graphene exhibits the most stable adsorption characteristics in the [Kr] 4d ¹⁻⁴ element series, which is independent of the vacancy type. Zr-doped single and double vacancy graphene sensors have higher sensitivity than Y, Nb, Mo.

After using the mixed acid system to modify the surface of rare earth minerals, two transition metals (Fe and Mn) are loaded on the surface of the rare earth minerals by hydrothermal method to improve the NH₃-SCR (Selective catalytic reduction) activity. In this paper, a variety of characterization means like SEM, XRD, BET, XPS, H₂-TPR (Temperature-programmed reduction), NH₃-TPD (Temperature-programmed desorption) and NO-TPD are used to study and analyze the surface properties of rare earth minerals before and after loading transition metals. Its catalytic performance was further measured in a simulated flue gas installation. The results show that the active elements on the surface of rare earth minerals after loading transition metals are mainly oxides. The specific surface area of rare earth minerals is effectively improved, the crystallinity of the active material is reduced, and the element distribution is more uniform. In addition, a composite structure of Fe-Ce and Mn-Ce is formed on the surface of rare earth minerals, and the oxygen vacancies and adsorption sites on the surface of the minerals are significantly improved. The NO_Xconversion rate for Fe-loaded mineral catalysts reached 89.1% at 300 ℃. The NO_Xconversion rate for Mn-loaded mineral catalysts reached 92.3% at 250 ℃. Generally speaking, the NH₃-SCR activity of rare earth mineral can be improved by loading transition metals (Fe and Mn).

Acid leaching and alkali roasting were used to remove impurities such as Ca and Si in Baiyun Obo rare earth concentrate. The effects of acid–base treatment on the physical and chemical properties of the samples were analyzed by scanning electron microscopy, X-ray diffraction, Brunauer–Emmett–Teller characterization, X-ray photoelectron spectroscopy, H₂-temperature-programmed reduction, NH₃-temperature-programmed desorption (TPD), and NO-TPD. Results showed that the content of Ce₇O₁₂ in the rare earth concentrates increased and the dispersion was uniform. The grains became smaller, the specific surface area of rare earth concentrates increased, and the active sites were more exposed. Ce coexisted in the form of Ce³⁺ and Ce⁴⁺, whereas Fe coexisted in the form of Fe³⁺ and Fe²⁺. The content of Fe³⁺ was increased. The acid–base-treated rare earth concentrates had a denitration efficiency of 87.4% at a reaction temperature of 400 °C.