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1

Study on the mechanism of action of various metal ions on the surface of monazite

Liu Rongxiang, Yang Zhanfeng, Li Jie, Cao Zhao, Li Qiang, Li Jichuan

Physicochemical Problems of Mineral Processing

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2024

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Vol. 60, iss. 2

art. no. 185901

EN

By studying the various metal ions released from the grinding process, and conducting the flotation test of monazite and symbiotic ore, using zeta potential measurements and FTIR infrared spectrum analysis methods, the influence of metal ions on the surface of monazite and the mechanism of action are obtained. The results showed that the main metal ions in the flotation environment of monazite are Ca2+, Ba2+, and Fe3+. When the pulp pH value was 8, Ca2+, Fe3+, and Ba2+ concentration was 3×10-4 mol/dm3, 3×10-5 mol/dm3, and was 2×10-4 mol/dm3 respectively, and OHA collector dosage was 5×10-4 mol/dm3, while the flotation recoveries of monazite, calcite. And fluorite was above 95 %, 40.43 %, and below 45.32 %, and the recovery rate of barite and bastnaesite in the presence of Ca2+ and Fe3+ is below 54.32 % and 38.68 %, respectively and the effective separation of monazite and symbiotic ore was obtained. The zeta potential measurements showed that when only metal ions are added to monazite, monazite (IEP) shifts to the right, and the negative charge on the surface of monazite decreases, which may be due to the positive charge of metal ions adsorbed on the surface of monazite, increasing the positive charge on the surface of monazite. When Ca2+, Ba2+, Fe3+, and OHA were added to the monazite pulp, the IEP of monazite moved to the left, and the negative charge of monazite shifted to the positive direction as a whole, indicating that Ca2+, Ba2+, and Fe3+ were adsorbed on the surface of monazite and increase the positive charge on the surface of monazite. When the pH value was 7 ~ 10, the surface of monazite was the same as that before and after the action of the agent, and both were negatively charged. At this time, OHA can still adsorb on the calcite, that was, the chemical affinity overcomes the same electric repulsion and adsorbs, so that the potential of the monazite after the action is reduced, which is chemical adsorption. The FTIR showed that when the metal ions Ca2+, Ba2+, and Fe3+ are added to activate the surface of monazite, the peak area of the organic functional group-CH2−CH3 at 3000-2800 cm−1 was enhanced, and a new peak appears at 1382 cm−1. The reason is that the N-O-H functional group of OHA collector was adsorbed on the surface of monazite, and a red shift (44 cm−1) occurs, and a new peak appears at 1454 cm−1. The reason is that the C-N functional group of OHA collector is adsorbed on the surface of monazite. The lone electron pair of the nitrogen atom of the amide group in the OHA forms chelates with Ca2+, Ba2+, and Fe3+ atoms, which further increases the adsorption amount of OHA. This showed that the adsorption of monazite surface by metal ions provides active sites for the adsorption of OHA collectors. These phenomena indicate that the adsorption capacity of OHA on the surface of monazite activated by Ca2+, Ba2+, and Fe3+ is enhanced and a stable five-membered ring metal chelate is formed. Combined with flotation results and zeta potential data, infrared spectroscopy analysis, the adsorption capacity of Ca2+, Ba2+, and Fe3+ activated monazite surface: Fe3+>Ca2+>Ba2+.

2

Fault analysis and reliability evaluation for motorized spindle of cycloidal gear grinding machine based on multi-source bayes

Wang Huiliang, Zhang Zhijie, Li Jie, Xin Wen, Han Chunyang

Eksploatacja i Niezawodność

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2024

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Vol. 26, no. 1

art. no. 175010

EN

A Monte Carlo simulation method based on multisource bayes is proposed to improve the reliability of motorized spindles in cycloid gear grinding machines and reduce their failure rate. Based on field investigations and motorized spindle maintenance records, a fault tree model of a motorized spindle was established, and the fuzzy importance of each bottom event was evaluated. The fault tree of a motorized spindle was used as a Monte Carlo reliability simulation model, and its importance was used as the input parameter for the simulation. The reliability evaluation index of the motorized spindle was obtained at different simulation times. The feasibility and accuracy of the reliability simulation were verified by comparing the importance and simulation importance. A vibration test was designed for bearing faults with high importance, and fault extraction was performed by combining the wavelet packet transform and empirical mode decomposition. This method can also be used to simulate and analyze the reliability of other equipment or machine tools.

3

The depression mechanism on pyrite in a low-alkaline system with combined depressants : Experiment, HSC, DFT and ToF-SIMS studies

Li Suqi, Yuan Jiaqiao, Ding Zhan, Li Jie, Yu Anmei, Wen Shuming, Bai Shaojun

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 3

art. no. 168454

EN

Depression of pyrite in a low-alkaline system has sparked soaring interests for the multi-metal sulfide minerals flotation recently. This study investigates effects of combined depressants (Ca(ClO)2 and CaO) on pyrite flotation with butyl xanthate (KBX). Micro-flotation experiments indicate that the addition of 200 mg/L combined depressants (a mass ratios of CaO to Ca(ClO) 2 of 2:3) and 1.0×10−3 mol/L KBX at pH 9.5 can effectively depresses the flotation of pyrite, and a minimum pyrite recovery rate of 12.5% is obtained. Basic thermodynamic evaluation results confirm the participation of Ca(ClO) 2 significantly decrease the negative Gibbs free energies of pyrite oxidation reaction. Besides, the calcium species (Ca(OH) 2, Ca2+ and Ca(Cl) 2) will spontaneously transform into CaCO3,and it is the ultimate dominant calcium species in the CO32- system. Density functional theory (DFT) results indicate that CaCO3 can chemically adsorb onto the pyrite surface with an adsorption energy of -671.13 kJ/mol. The O1 and Ca atoms mainly contribute to the bonding process and are responsible for the stable adsorption of CaCO3. ToF-SIMS results provide strong evidence that the combined depressants increase the amount of hydrophilic species and decrease dixanthogen adsorption onto the pyrite surface. The thickness of the whole formed hydrophilic species is approximately 50 nm. Semiquantitative amounts of hydrophilic species follow the order of hydroxy calcium>iron carbonyl>calcium carbonate. Overall, hydrophilic species repulse adsorption of dixanthogen and significantly reduce the flotation performance of pyrite.

4

Study on the mechanism of the difference in flotation performance between fine-grained crystalline SiO2 and amorphous SiO2

Ma Saisai, Li Jie, Wang Yonglun, Wei Bangqi

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 6

art. no. 174567

EN

Numerous minerals found in nature contain silica, including quartz, cristobalite, opal, etc. They have the same chemical composition but different crystal structures, and this phenomenon is called “polymorphism” in mineralogy. For these polymorphic and multi-like minerals, in the flotation process, will it directly or indirectly affect the flotation effect. Based on this, this study mainly explores the difference between crystalline SiO2 and amorphous SiO2 in flotation. In this study, two crystal forms of SiO2 were subjected to flotation and adsorption capacity tests. FTIR, other test techniques, the chemical calculation of the flotation solution, and the theoretical calculation of the DLVO can all be used to provide an explanation. Finally, in the flotation experiment, the feedbacks of the two minerals to the change of the pH value of the pulp and the change of the concentration of the reagent are different. Through the comprehensive analysis of the adsorption capacity test and semi-quantitative calculation of the infrared spectrum, the adsorption capacity of crystalline SiO2 to drugs is about 23% higher than amorphous SiO2. Furthermore, during the flotation process, the amorphous SiO2 particles will agglomerate together and entrain into the foam through, resulting in concentrate pollution. So amorphous SiO2 will undoubtedly increase the difficulty of flotation.

5

Mechanism of Ca2+/Fe3+-based synergistic activation of quartz

Liu Rongxiang, Yang Zhanfeng, Li Jie, Li Qiang, Wang Zhenjiang, Luo Xiaofeng

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 1

art. no. 162262

EN

Although the flotation behaviors of iron concentrate and quartz are significantly different, quartz is the primary factor that affects the quality of iron concentrate. The flotation mechanism of quartz in the presence of mixed cationic Ca2+/Fe3+-co-activated SDS catcher was studied by conducting flotation tests with pure quartz mineral. The solution chemical calculation method, zeta potential calculation method, Fourier transform infrared (FT-IR) spectroscopy technique, X-ray photoelectron spectroscopy (XPS) technique, and other techniques were used to conduct the studies. The results showed that the maximum Ca2+/Fe3+-based synergistic activation of the flotation recovery process could be achieved in a certain range of pH values when three different activators were added sequentially. Analysis of the zeta potential values revealed that the Ca2+/Fe3+-activated quartz surface improved the extent of positive electricity generated and enhanced the SDS adsorption ability of the quartz surface. Results obtained using the FT-IR technique revealed that Ca2+/Fe3+ exerted a synergistic effect, and the adsorption process exploited the single oxygen bond interactions in the monovalent hydroxyl complex Ca(OH)+ and the double oxygen bond interactions in the Fe(OH)3 precipitates. Results obtained using the XPS technique revealed that the synergistic effect exerted by Ca2+/Fe3+ was significantly stronger than that exerted by Ca2+ or Fe3+ alone. The stable Fe-based six-membered chelate ring was formed on the surface of quartz when Fe3+ was the activator, and the chain-like Ca-based complex was formed when Ca2+ was the activator. The adsorption process on the surface of quartz proceeded following chemical as well as physical adsorption pathways. The results revealed that Ca(OH)+ and Fe(OH)3 played prominent roles during the activation of quartz surfaces in the presence of Ca2+/Fe3+.

6

Disk cutter wear prediction of TBM considering sliding and rolling friction

Huang Yuanjun, Hao Rujiang, Li Jie, Guo Jingbo, Sun Yankun, Liu Jiangran

Materials Science Poland

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2023

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Vol. 41, No. 1

42--56

EN

Considering the serious wear of disk cutters in tunnel project and the low prediction accuracy of existing methods, a new method for wear prediction of disk cutters from an energy perspective was proposed. Based on contact mechanics, the rock breaking process of cutters was analyzed, and the combined action of sliding and rolling friction was considered. Furthermore, the wear prediction model of disk cutters was established, which realized the predicted wear of disk cutters under different geological conditions throughout the construction line. In addition, considering the influence of penetration on the wear prediction model, the predicted wear values under different penetrations were obtained, and their average values were taken as the predicted wear values of disk cutters considering penetration. Finally, the predicted wear values were compared with the actual wear value of disk cutters. The results showed that the average relative error between the predicted wear value of disk cutters considering sliding and rolling friction and the actual wear data was 12.8%. The average relative error between the predicted value of wear considering only sliding friction and the actual value of disk cutters is 18.3%. The average relative error between the predicted value of disk cutter wear considering penetration and the actual wear data was 12.2%, which proved the feasibility and accuracy of the prediction model. Meanwhile, it is more accurate than the model only considering sliding friction. The research results provided a scientific theoretical basis for the design of a tool change scheme in tunnel construction.

7

Study on fluoride fixation effect of Bayan Obo rare earth iron ore and three sodium agents under microwave irradiation

Guo Jing, Wen Ming, Li Jie, Hong Xunhai, Zhang Wenhao, Wang Yonglun

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 1

63--76

EN

To investigate the fluorine fixation of Bayan Obo rare-earth iron ores in beneficiation and metallurgy processes, the effect of three sodium agents, namely, sodium hydroxide, sodium carbonate, and sodium bicarbonate, on fluorine fixation under the action of microwaves was investigated using Xray diffraction, chemical detection, and orthogonal experiments. The effects of different types of sodium, roasting temperatures, sodium ratios, and roasting times on the fluorine fixation rate were evaluated. Results show that compared with conventional roasting, the fluorine fixation efficiency of Bayan Obo rare-earth iron ore under the action of microwave is superior after the formulation of the sodium agent, which is crucial for the study. Among the three sodium agents, the fluorine fixation effect of NaHCO3 can be used as the preferred sodium agent. Orthogonal experiments showed that the factors influencing the magnitude of the fluorine fixation rate are the roasting temperature, sodium agent ratio, and roasting constant temperature time in the order of priority. The optimal conditions for the fluorine fixation process are the microwave roasting temperature of 973.15 K, sodium bicarbonate ratio of 40%, and roasting time of 60 min. The highest fluorine fixation rate of 86.72% can be obtained. The findings of this study can provide a reference for the development of green and economic recovery processes for Bayan Obo rare-earth iron ores.

8

Selective depression of Escherichia coli on flotation of collophanite and dolomite

Li JiaXin, Nie GuangHua, Jiang Ying, Luo GuoJv, Li Jie

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 4

art. no. 150604

EN

The phosphate rock flotatio n test was carried out using Escherichia coli E. coli ) as a depressant of dolomite. The results showed that E. coli had a great selective depression on dolomite during flotation. With E. coli as a depressant of dolomite, a useful beneficiation index of phosphorus concentrate with P2O5 grade of more than 30% and MgO content less than 1.2% can be obtained by closed circuit of one stage roughing and one stage cleaning. Furthermore, the depression mechanism of E. coli was studied by ad sorption experiments, infrared spectrum, and zeta potential. This study shows that the adsorption ability of E. coli onto dolomite is stronger than that of collophanite. When the pH is greater than 6, E. coli are chemically adsorbed on the surface of the c ollophanite and dolomite,which also increases the negative charge on the surface of the two minerals. The selective adsorption of E. coli cells to dolomite was best when the pH value is about 7.8.

9

An innovative flotation technology for the lime-depressed pyrite recovery from copper sulphide ore via acid mine drainage (AMD) activation

Yuan Jiaqiao, Ding Zhan, Bi Yunxiao, Li Jie, Wen Shuming, Bai Shaojun

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 6

art. no. 152609

EN

In this study, an innovative flotation technology consisted of Cu differential flotation with high alkali lime and pyrite recovery with acid mine drainage (AMD) activation was investigated for the cleaner beneficiation of the copper sulfide ore. Flotation test results showed that H2SO4 -CuSO4 and AMD could effectively activate the pyrite flotation with SBX collector. Moreover, the recovery of S concentrate is increased by 5.33% in the AMD system. Adsorption amount results of SBX collector indicated that the hydrophilic species (Ca2+, CaOH+ and FeOOH) were formed on the pyrite surfaces in the high alkali lime craft (pH=11.3) and degraded the interaction between SBX and pyrite surfaces. AMD can effectively clear off the hydrophilic calcium species and the copper ions originated from the AMD absorb onto the pyrite surfaces, facilitating the SBX collector adsorption. Composition analysis results of tailings water confirmed that the tailing water obtained by the AMD flotation system was more desirable to be recycled in the Cu differential flotation due to its higher pH value (8.7). The present study provides a novel approach for the treatment of AMD, and has the vital practical significance for the emission reduction of AMD and the increase of beneficiation profits.

10

Citric acid inhibits the floatability of quartz in the Mg2+ system

Wang Yonglun, Li Jie, Zhang Wenhao, Li Pengwei, Guo Jing, Yao Kai

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 6

1--11

EN

Citric acid is a small-molecule organic acid, which can be used as an inhibitor for the flotation of Mg2+ activated quartz. Methods such as flotation experiments, zeta potential, FTIR qualitative and quantitative calculations, and solution chemistry calculations were used in this study to conduct systematic research to study activation and inhibition mechanisms. The results show that adding only a quarter of citric acid under the optimal conditions of Mg2+ activated quartz produces the best inhibitory effect. Mg2+ and citric acid affect the zeta potential of the quartz surface in the zeta potential experiment. FTIR qualitatively found that under the action of Mg2+, sodium oleate was adsorbed on the quartz surface in the form of physical adsorption; quantitative analysis clearly explained that after the chemical reaction between citric acid and Mg2+, it desorbed from the quartz surface into the water system. According to the chemical calculation of the solution during the flotation process, it is found that the reaction product of citric acid and Mg2+ has no inhibitory effect; only the amount of Mg2+ is consumed, thereby reducing the number of activating factors and cutting off the medium of sodium oleate adsorbed on the surface of the quartz.

11

Theoretical and experimental investigation of sliding instability in blocky rock system triggered by external disturbance

Jiang Hai-ming, Li Jie, Deng Shu‑xin

Acta Geophysica

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2019

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Vol. 67, no. 3

775--787

EN

Based on the structural hierarchy theory, rock masses can be considered as a blocky rock system capable of storing various kinds of a large amount of energy. As the development and utilization of underground space has extended to thousands of meters, the increasingly frequent rockbursts pose a great danger to the constructors and equipment at the construction field. According to its mechanism, rockburst can be broadly divided into strain failure type caused by rock volume damage and sliding failure type caused by fault-slip event. This paper focused on investigating the triggering mechanism of sliding type rockbursts induced by external disturbance. With the simplified theoretical model of contact slipping between rock masses under the condition of initial stress, a non-dimensional impact energy parameter I was derived to quantify the critical conditions of different types of sliding failure events along structural plane. Then the necessary conditions for the occurrence of fault-slip rock burst were derived: Firstly, the contact surfaces of the rock block are in the quasi-stable state with the high initial stress in the tangential direction; secondly, the impact energy factor which characterizes the movement of the rock mass reaches a critical value under the dynamic disturbance. To verify the theoretical result, a series of sliding tests were carried out for purple sandstone blocky system under various horizontal pulls and vertical impact loadings. Both the irreversible displacement and sustained sliding instability are observed, and the critical energy conditions of above-mentioned phenomenon are obtained, which are consistent with the theoretical model. Furthermore, numerical modeling calculations considering rock mass vibration and the slip rate weakening mode of rock friction were performed to better understand the mechanism of sliding instability caused by external disturbances. These results provide a theoretical reference on the safety of underground tunnel construction.