To gain an in-depth understanding of research status of ceramic additive manufacturing, the technical processes of direct ink writing, fused deposition modeling, selective laser sintering, stereolithography and digital light processing, as well as the materials used in those technologies are reviewed based on domestic and international researches on ceramic additive manufacturing. The advantages and disadvantages of those five technologies are summarized, which can provide references for their application scenarios. Finally, the prospect for the development of ceramic additive manufacturing is also discussed.

Bagasse was calcined under an inert atmosphere to produce biochar, which was then mixed with metakaolin and taken to prepare sugarcane bagasse biochar/geopolymer composite microspheres (BGM) by using sodium silicate as an activator. The microstructure of BGM was characterized by XRD, FTIR, BET and XPS, and its adsorption performance for crystal violet (CV) and methylene blue (MB) was also investigated. Results show that the introduction of biochar can enhance the adsorption capacity of metakaolin-based geopolymer microspheres. The adsorption processes of BGM for both dyes follow the pseudo-second order kinetic model. BGM-20 can have theoretically maximum adsorption capacities of 138.031 mg/g for CV and 79.128 mg/g for MB, which can be well-described by the Langmuir isotherm model. Dynamic adsorption experiments revealed that the time required for adsorption of CV and MB by BGM to reach exhaustion exceeded 8 500 min, indicating that BGM can be taken as a fixed-bed adsorption medium material for dye wastewater treatment.

Based on the analysis of patent application trend, major applicants and technological development in recycling of spent lithium iron phosphate batteries by leaching process, a list of key patents of mainstream technologies is presented. The results show that the number of patent applications for recycling of spent lithium iron phosphate batteries by leaching process has been steadily increasing since 2015, and oxidative acid leaching is the mainstream technology at present, with other technologies keeping in pace. However, some outdated technologies are being phased out.

In order to study the high-temperature and high-pressure sintering of binderless tungsten carbide (WC), X-ray diffraction, scanning electron microscopy, universal testing machine, and microhardness tester among others were adopted to characterize the phase composition, microstructure and mechanical properties of the WC samples. The results show that the relative density, hardness and fracture toughness of the samples increase as the sintering temperature rises. It is found that WC sample prepared by sintering at 1 500 ℃ can exhibit excellent comprehensive mechanical properties, with relative density of 99.5%, hardness of 2 885HV, and fracture toughness of 9.50 MPa·m^1/2.

Based on process mineralogy study, a processing technique consisting of atmosphere roasting and leaching with dilute sulfuric acid was proposed to separate a kind of mixed rare earth concentrate containing 48.23% REO. It is found that the phase composition of such concentrate is mainly composed of bastnaesite, monazite, apatite and fluorite, with rare earth elements primarily existing in bastnaesite and monazite. Under air/argon atmosphere roasting, phases of monazite, apatite and fluorite can remain stable, and phase transition is mainly attributed to bastnaesite reaction. In an air atmosphere, bastnaesite is transitioned in the following steps, CeFCO₃→Ce₇O₁₂→Ce₁₁O₂₀→CeO₂, while its transition steps in an argon atmosphere include CeFCO₃→Ce₇O₁₂, Th_0.5Ce_0.5O_1.84→CeOF. After roasting in an air atmosphere at 500 ℃ followed by leaching with dilute sulfuric acid, the leaching rates of F-REO and P-REO can reach 86.67% and 1.70%, respectively, while the process of roasting at 700 ℃ in an argon atmosphere can lead to the leaching rates of F-REO and P-REO at 75.97% and 13.33% respectively. And the leaching residues obtained from above-mentioned two different processes have F-REO and P-REO contents of 6.92%, 26.02% and 11.86%, 21.81% respectively, all dominated by monazite. It is concluded that this processing technique of atmosphere roasting followed by dilute sulfuric acid leaching can effectively achieve separation between bastnaesite and monazite.

A chrysoberyl-type beryllium ore from Xinjiang, containing 0.102% Be with quartz as the dominant gangue mineral, was taken in an experimental study on sulfuric acid leaching. According to the Box-Behnken experimental design principle, a multivariate regression equation was established by using response surface methodology (RSM) for three influencing factors of leaching effect, including liquid-solid ratio, leaching time and leaching temperature, as well as their interactions. Based on the test of significance of regression equation, the optimum process conditions were determined as follows: roasting temperature of 900 ℃, roasting time of 3 h, sulfuric acid concentration of 50%, liquid-solid ratio of 3.2∶1, leaching time of 4.8 h and leaching temperature of 90 ℃. Under these conditions, the Be leaching rate is predicted to be 89.73%, and an average value is 89.10% based on three parallel experiments, indicating that the established model is accurate. A kinetic model of leaching revealed that the leaching process was controlled by interfacial chemical reactions, with an apparent activation energy at 50.42 kJ/mol.

As for the molybdenum ores from Yichun Luming Mine, an m-order grinding kinetics model was used to explore the effects of four grinding aids, such as triethanolamine (TEA), triisopropanolamine (TIPA), polyacrylic acid (PAA) and polycarboxylic ether (PCE), on grinding kinetics of molybdenum ores. The results show that before addition of grinding aids, the proportion of the milled product in the size range of -0.074 mm increases significantly with the increase of the medium charge ratio, and the grinding kinetic parameters of m and k all increase; with the same medium charge ratio, the parameter of m increases and the parameter of k decreases as the grain size of milled product decreases. Comparatively, as for the samples milled with grinding aids of TEA, TIPA, PAA and PCE, the milling products in the size range of -0.074 mm increase by 6.19, 2.40, 3.62 and 1.89 percentage points, respectively. Compared to the system without grinding aids, an addition of TEA can lead to higher values of parameters of k and m, and larger particle size can result in great decline in the k value, while small particle size can bring a gentle k-grain curve, indicating the k value plays a dominant role at the initial grinding stage. After addition of grinding aids, the grains present improved dispersibility with significantly less agglomeration.

In order to investigate the reaction behavior of associated thallium sulfide in zinc concentrate during fluidized roasting, thermodynamic calculation and verification experiments were conducted for the oxidation process of thallium sulfide. Firstly, the volatilization of thallium chloride, thallium oxide, metallic thallium and thallium sulfide were analyzed based on data retrieval and calculation, and the volatilization of those four matters was determined in the following descending order: Tl₂O>TlCl>Tl₂S>Tl. Then, the equilibrium analysis and the calculation of Gibbs free energy change of the Tl₂S-O₂ system were conducted. It is shown that Tl₂S volatilizes violently in an inert atmosphere as temperature rises, and decomposes into Tl and sulfur vapor after temperature is above 1 000 ℃. However, in an oxidizing atmosphere, Tl₂S begins to generate a large quantities of Tl₂SO₄ after the temperature reaches 100 ℃, and a few of Tl₂S begins to decompose into SO₂ and Tl₂O after temperature is above 1 000 ℃. No interaction occurs between Tl₂S and ZnO. In the practical roasting process, Tl₂S is completely converted into Tl₂SO₄ and remains stable in the calcine at the temperature above 800 ℃, which can be intensively removed in the subsequent open-circuit of leaching and purification process.

Surfactants of Span80 and Tween80 were adopted to emulsify diesel in an experiment. Based on the studies on effects of diesel microemulsion on the concentrate recovery rate by graphite flotation and fuel-saving efficiency, the optimal conditions for preparing diesel microemulsion were determined as follows: emulsifier's hydrophilic-lipophilic balance (HLB) value of 9, n-butyl alcohol as a co-emulsifier, and emulsifier and co-emulsifier in a mass ratio of 2∶1. Under these conditions, the diesel microemulsion can be prepared with an average particle size of 78.82 nm and uniformly dispersed, presenting excellent stability. Flotation experiments showed that the usage of diesel microemulsion could save 28.66% of oil. And the mechanism of interaction between diesel microemulsion and graphite reveals that diesel microemulsion can significantly reduce the surface tension of the pulp, thus increasing the contact angle of graphite, leading to a higher flotation recovery rate compared to the adoption of conventional diesel.

Based on the optimization of flotation parameters of a low-grade spodumene ore from Sichuan, processing tests were conducted by adopting four flotation schemes to investigate their advantages and disadvantages. It is found that both the process of flotation with full-size range of ores followed by middling regrinding and the process of desliming followed by flotation and sequential returning of middlings are more advantageous than the conventional flowsheet of flotation with full size-range of ores followed by just sequential returning of middlings. It is shown that Li₂O recoveries by two processes can be increased correspondingly by 1.08 and 1.53 percentage points, and the second processing technique can bring a higher Li₂O recovery at 86.7%. However, the first processing technique can produce a higher quality lithium concentrate with a Li₂O grade of 5.76%.