The factors and reasons influencing lime activity are presented, and the influencing mechanism of lime activity for digestion performance of bauxite is also expounded. It is found that the particle size of limestone and calcination temperature are two important factors influencing activity of lime. At a calcination temperature of 1 000 ℃, the activity of lime is as high as 33.5 mL, while with the particle size of limestone increased to 17.5-22.5 mm, the activity of lime increases to 46 mL. The analysis results of scanning electron microscopy show that highly active lime has fine particles with uniform particle size and in a structure of honeycomb with well-developed and interconnected pores. The experiment of bauxite digestion shows that the activity of lime and its adding amount will bring influence to the digestion rate of bauxite and the phase composition of red mud. By adding highly active lime with a C/S ratio of 1.0, the relative digestion rate of bauxite is as high as 98.12%.

Aiming at obvious elastic-plastic deformation of diamond drill bits in the process of drilling marine gas hydrate, a modeling approach that is suitable for the core drilling process of drill bits was proposed based on the Hertz theory. Firstly, the rock-breaking mechanism was analyzed for marine gas hydrates from elastic deformation to elasticplastic deformation during the drilling process under sea, and the drilling pressure and cutting force of single diamond particle on the diamond bit during the drilling process were calculated. Secondly, according to the stress condition of a single diamond particle, the theoretical relationships between drilling pressure and torque on the whole bit and other drilling parameters were obtained, and a mechanical model was established for the diamond drilling bit. Finally, a relationship curve between the saturation of marine gas hydrate and the torque and drilling pressure was obtained based on analysis. An at-sea testing by adopting such method has successfully taken some samples of marine gas hydrate, which has verified the feasibility of this method. This research provides a theoretical reference for the design of drill bit parameters and optimization of efficient deep-sea core drilling operation.

An experimental study was carried out on fluoride removal from the wastewater after acid leaching process in one enterprise. In the experiment, zirconia was used in the 1^st-stage reaction and amorphous aluminum hydroxide was adopted in the 2^nd-stage reaction for fluoride removal, and effects of reaction temperature, reaction time and adding amount of zirconia-based reagent on the fluoride removal effect were explored. It is found that both higher temperature and longer reaction time can promote fluoride reduction effect of fluoride removing reagent.1^st-stage reaction ran for 50 min at 75 ℃ with an addition of 50 g/L zirconia-based reagent, the fluoride reduction rate was up to 96% and fluoride mass concentration in the wastewater was reduced from 600 mg/L to 25 mg/L. After that, 2^nd-stage reaction at 70 ℃ ran for 60 min, by adding 5 g/L amorphous aluminum hydroxide, the fluoride mass concentration in the wastewater was down from 25 mg/L to 6.5 mg/L. It is shown that the residue left after fluoride removal process has a good crystal structure and obvious diffraction peak. XRD analysis shows that Na₃AlF₆ is the main component in the residue.

A review of comprehensive recycling technologies for graphite anodes in spent lithium-ion batteries is presented, including hydrometallurgical process, a combination of pyrometallurgical and hydrometallurgical process, as well as mechanical recycling. And then, an in-depth analysis of advantages and disadvantages of each technology is also presented. It is particularly pointed out that there are various recycling technologies, but the development of an efficient and environmentally-friendly closed-circuit recycling process still faces challenges. The recycling approaches of graphite anodes in spent lithium-ion batteries are discussed in details, such as usage as anodes of rechargeable batteries, or for preparation of graphene. The research direction in the future is also forecasted aiming to provide theoretical and technical support for reutilization of graphite anodes in spent lithium-ion batteries with high-value added. It is suggested that research should focus on developing a simple, efficient and clean closed-circuit recycling processes to improve the recovery rate and purity of graphite anode materials while reducing environmental pollution. The research hotspots in the future should include lattice reconstruction and repairing technologies for graphite anode materials, as well as exploration of new applications of graphite anode materials in the fields of energy storage materials, catalysts, adsorbents among others.

Based on the engineering geological data and the anchoring support scheme for a foundation pit, a three-dimensional geological generalization model was constructed with ANSYS software for the foundation pit of one bridge over the Yangtze River. This model was then imported into FLAC^3D to simulate and analyze the stress, deformation and plastic zone evolution characteristics of the foundation pit during the process of excavation and anchoring support. The results show that during the excavation of the foundation pit, the rock mass is generally subjected to well-distributed compression, with less concentrated stress. After excavation, the foundation pit generally appears to have an upward rebound deformation, with the displacement of bottom plate maximally reaching 14.7 mm. It is shown that the counter-trend slope on the north side has the maximum deformation up to 8.65 mm. The volume of the plastic zone continues to increase, and then decreases during the excavation of the last step. After the excavation is completed, a large number of plastic zones appear in the rock mass on the north side of the foundation pit. Compared to the support scheme with only anchor rods, the support with anchor rods together with anchor cables can make the deformation of the rock mass of slope on the north side reduced by 16.6% on average, as well as the volume of plastic zone reduced by about 8 600 m³ and the distribution depth reduced from 15 m to 5 m after excavation is completed. It is concluded that the support scheme with both anchor bolts and anchor cables can not only effectively suppress the deformation of the slope on the north side, but also effectively reduce the distribution depth of plastic zone in the rock mass and improve the stability of rock mass, presenting better support effect for the foundation pit slope.

A mineral processing test was conducted to treat a lithium-tantalum-niobium-beryllium polymetallic ore with a lithium grade of 0.68% from Xinjiang. According to the process mineralogy study, this ore has spodumene as the dominant lithium minerals, and has low content of tantalum-niobium minerals. A flowsheet including a magnetic separation and gravity separation to recover tantalum-niobium minerals, and a flotation to collect lithium minerals can produce a tantalum-niobium concentrate with Ta₂O₅ grade and recovery of 17.110% and 41.69%, Nb₂O₅ grade and recovery of 19.670% and 42.63%, respectively, and a lithium concentrate with Li₂O grade and recovery of 5.12% and 75.21%, respectively.

In order to optimize the particle shape and gradation of machine-made sand, a vertical bar stirring mill was adopted for shaping tests. The effects of medium type, medium ratio, mill rotation speed and material/ball ratio on the particle shape of machine-made sand were investigated. The gradation and shape characteristics of unshaped and shaped sands were comparatively analyzed by using optical microscopy and image processing software. The results show that the shaping effect of zirconia medium is better than that of steel or alumina medium. With the zirconia balls with diameter of 6 mm and 8 mm in a mass ratio of 1∶1, rotation speed of 300 r/min, feed/ball mass ratio of 1∶3 and pulp volume fraction of 62.5%, the milling process results in the shaped sand with fineness of+0.15 mm 84.98% and flake granule accounting for 4.5%. The shaped machine-made sand has better compactness and angular characteristics, and it is qualified as the type I sand according to the standard GB/T 14684—2022, with better gradation and particle shape compared to the unshaped sand. The contour shape and angular characteristics of coarse granules can be greatly optimized than those of fine particles. It is concluded that under suitable conditions, a vertical bar stirring mill can obviously improve the shape of machine-made sand and optimize coarser grain composition.

An experimental study was carried out for adsorption of ammonia nitride and copper ions in electroplating wastewater by fly ash-based zeolite. Results show that the proper conditions for adsorption of copper ions by fly ash-based zeolite include pH of 8, initial mass concentration of 200 mg/L for copper ions in the solution, adsorption time of 0.45 h, and temperature of 200 ℃; the proper conditions for adsorption of ammonia nitride by fly ash-based zeolite include addition of 8 g/L fly ash-based zeolite, pH of 8, adsorption time of 0.60 h, and initial mass concentration of 150 mg/L for ammonia nitride in the solution. It is found that the adsorption of copper ions by fly ash-based zeolites is a physical adsorption process, and the adsorption of ammonia nitride by fly ash-based zeolites is a combination of ion exchange and physical adsorption.

Red mud was pre-treated with process of reduction roasting followed by magnetic separation, and the obtained non-magnetic material was calcined and then dissolved in hydrochloric acid. After that, it was filtered after addition of saturated sodium meta-aluminate polymerizing agent, and then matured to prepare polymeric aluminum chloride (PAC) base liquid, which was used in a purification test. With PAC-base liquid and manganese-containing wastewater in a volume ratio of 1∶120, stirring speed of 140 r/min, pH of 8, reaction temperature of 30 ℃, and addition of polyacrylamide (PAM) at an amount of 20 mg/L, the manganese mass concentration in the wastewater reduced from 325.3 mg/L to 1.5 mg/L after 5 hours of settlement, showing manganese removal rate up to 99.5%. It is shown that the manganese mass concentration in the purified liquid can meet class Ⅰ limit in the national discharge standard.

For discussing rational sequence of drift stoping by cemented backfilling under complex stress conditions, with No.2 mine of Jinchuan Group as an example, a three-dimensional numerical model was constructed with a numerical simulation software, and was then used to analyze the stress field, displacement field and plastic failure zone in drift stoping with different sequences. On this basis, the drift stoping sequence, after optimization by adopting a combined weighting and fuzzy comprehensive evaluation, was then adopted in an on-site industrial experiment. The results show that both mining sequence by overhand or underhand stoping and drift stoping with different spatial sequence can bring a certain influence to the maximum principal stress, maximum tensile stress, vertical displacement, plastic failure zone, as well as the maximum principal stress and vertical displacement in the next stope nearby; mining sequence of underhand stoping followed by overhand stoping, or firstly drift stoping of vertical ore mass, can make the overall mining with higher safety. The on-site experiment with such mining sequence presents better effect. It is concluded that this research can provide some reference in the design and optimization of mining sequence for drift stoping by cemented backfilling under complex stress conditions.