Latest ArticlesBased on the combination of the hunger games search (HGS) algorithm and the artificial neural network (ANN), a new hybrid model of HGS-ANN was developed to predict blasting vibration. Four different prediction models were established based on group method of data handling (GMDH), support vector machines (SVM), ANN and Sadov's empirical formula, and compared with HGS-ANN model in evaluating the performance of models. For this purpose, 32 sets of blasting data of an open-pit mine were collected.7 independent variables, including detonation distance, maximum single-stage charge, total charge, burden, hole spacing, number of holes and hole depth were selected as inputs, while the particle vibration velocity was selected as the output. With the root-mean-square error (RMSE) and the decisive factor (R2) as the evaluating indicators, the established models was compared in terms of their performances. The results show that the HGS-ANN model, with the RMSE and R2 of 0.833 and 0.963, respectively, has performance better than the other four models. It is proposed that the HGS-ANN model can be used as an auxiliary tool to optimize the blasting design for reducing the blasting-induced seismic effect.
With vanadium pentoxide and citric acid as raw materials, a kind of 3D flower-like VO2(B) electrode material with large specific surface area and excellent structural stability was prepared by adopting hydrothermal synthesis. The crystal structure and morphology of the VO2(B) electrode material were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope, and the electrochemical properties of VO2(B) electrode material were measured by constant current charge and discharge, as well as cyclic voltammetry. The results show that the first specific dischage capacity of 3D flower-like VO2(B) electrode material is 227 mAh/g at a current density of 0.1 A/g. It delivers the first specific discharge capacity of 151 mAh/g at a high current density of 1 A/g, and retains 79.6% of this capacity after 300 charge-discharge cycles, exhibiting a good rate performance.
A kind of hydrogen storage alloy of La0.7R0.1Mg0.2Ni3.35Al0.15 (R=La/Nd/Sm) was synthesized with induction melting method, and the effect of La substituted with rare earth element Nd/Sm on the phase structure, microstructure, and electrochemical performance of the hydrogen storage alloy was explored. The results show that the substitution of Nd or Sm for La doesn't change the phase composition of the hydrogen storage alloy, which is still composed of LaNi5, (LaMg)2Ni7, and (LaMg)5Ni19 phases, but leads to higher abundance of LaNi5 and (LaMg)5Ni19 phases, and lower abundance of (LaMg)2Ni7 phase in the hydrogen storage alloy. The hydrogen storage alloy, with La, Nd and Sm as R, deliver the maximum discharge capacities of 377 mAh/g, 382 mAh/g and 376 mAh/g, respectively, after the second charge-discharge cycle. With La substituted with Nd or Sm, the hydrogen storage alloy has its high-rate discharge capacity, the charge retention rate after 24 hours, and capacity retention rate after 100 cycles all improved to some extent, among which the hydrogen storage alloy with Nd as R is the best in all corresponding performance. Moreover, the substitution of La with Nd or Sm can make the hydrogen storage alloy with higher exchange current density and higher coefficient of hydrogen diffusion. Its high-rate discharge performance, exchange current density and hydrogen diffusion coefficient are all in in the same trend, indicating that high-rate discharge performance of the hydrogen storage depends on both exchange current density and hydrogen diffusion coefficient.
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.
As for the open-pit slope with fault structure, studies on its deformation and failure characteristics were carried out by means of remote sensing images, field investigation and numerical simulation, and its safety factor was also calculated, so as to explore the influence of fault structure on slope stability. Then, based on the analysis of deformation and failure process of slope, the failure rule for open-pit slope with fault structure was discussed. It is found that the landslide hazard occurring on the north slope of the open-pit mine is attributed to an internal factor of fault structure combined with an external factor of unloading by underground mining. Under the combined action of disturbance by underground mining and cutting by F15 fault, a landslide is prone to occur along the fault structure, and then the failure zone will be gradually expanded. The deformation and displacement of upper slope above the F15 fault structure becomes relatively larger, and proceeds towards the eastern bottom along the F15 fault structure. The F15 fault structure changes the deformation and failure trend of the upper part of the northern slope. It is shown that when the safety factor of open-pit slope is 1.45, F15 fault zone is the potential sliding plane, and no larger deformation has occurred along the fault zone of the northern slope.
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 FLAC3D 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.
With silicon material (BFSi) extracted from blast furnace slag as silicon source and polyacrylonitrile (PAN) as carbon source, a kind of silicon-carbon anode material for lithium-ion batteries was synthesized. And the influence of ratio of silicon to polyacrylonitrile on the BFSi@C material was investigated. Results show that BFSi@C synthesized with BFSi and PAN in a mass ratio of 3∶1 delivers an initial charge capacity of 1 884.99 mAh/g at a current density of 0.5 A/g. After 100 cycles, it still delivers a specific charge capacity of 1 509.32 mAh/g, with a capacity retention rate of 80.07%. Moreover, it presents excellent rate performance at high current densities. Compared with commercial silicon materials, BFSi@C demonstrates higher cycle capacity and superior rate performance, delivering a specific capacity up to 538.31 mAh/g at a current density of 5 A/g.
With the calcium-magnesium slag generated in recycling process of spent Li-ion batteries as raw material, battery-grade lithium carbonate was prepared by adopting a process consisting of leaching for decomposition, purification, lithium precipitation and carbonization for decomposition. The results show that with the addition of MgSO4·7H2O at 1.1 times of the theory amount, initial pH of 1.5, reaction time of 2.0 h, solid-liquid ratio of 1∶6, reaction temperature of 90 ℃, and final pH of 3.5, the leaching rate of Li can reach 98.39% and the mass concentration of Li in the lixivium is 18.03 g/L. Then, the obtained lixivium is subjected to processes of defluorination with resin, impurity removal with NaOH, and Na2CO3 precipitation, and crude lithium carbonate can be obtained with purity of 95.11%. By adopting a process consisting of carbonization, removal of calcium and magnesium with resin, and pyrolysis, a battery-grade lithium carbonate with purity of 99.64% can be prepared. It is shown that by using this processing technique, the lithium recovery rate can reach 95.08%, presenting good prospect in industrial application.
In order to improve the accuracy of the GRU neural network model in predicting the remaining useful life (RUL) of lithium-ion batteries, the GRU model was optimized based on PCA-GWO and then applied in the prediction. The results show that compared with the traditional GRU model, the PCA-GWO-GRU model presents higher prediction accuracy. When the starting point of the prediction is 90% of the original data, the prediction accuracy can reach the highest, with the corresponding RMSE of 0.004 9, MAE of 0.003 6, and R2 of 0.986 3.
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.