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3 2024

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Depressant-free flotation separation of chalcopyrite and galena by surface oxidation pretreatment: Effect of applying potassium peroxymonosulfate as a novel and efficient oxidant

Zhou Hepeng, Guo Jiangfeng, Zhu Guangjie, Xu Hao, Tang Xuekun, Luo Xianping

Physicochemical Problems of Mineral Processing

2024

Vol. 60, iss. 6

art. no. 195497

The flotation separation of chalcopyrite and galena presents significant challenges due to their similar surface properties, resulting in comparable floatability. In the process of flotation separation, conventional depressants encounter issues related to high toxicity or limited effectiveness. In this paper, it was found that the floatability of galena decreased significantly after pretreatment with potassium peroxymonosulfate (PMS) oxidation. The influence on chalcopyrite, however, is relatively insignificant. In flotation tests of mixed binary minerals, without PMS oxidation, the two minerals are basically floating; When the pH is 8 and the dosage of PMS is 0.375 g/L, it is possible to obtain a flotation concentrate with a Pb grade of 26.78% and recovery of 36.10%, as well as a Cu grade of 21.53% and recovery of 83.66%, when the raw ore contains Pb 44.88% and Cu 15.57%. The oxidation pretreatment method enables the separation of galena and chalcopyrite without the need for a depressant. The XPS and AFM measurements revealed a significantly higher oxidation degree of galena compared to chalcopyrite after treatment with PMS, indicating a notable difference in their floatability. Consequently, the separation of chalcopyrite and galena is greatly facilitated by this distinction. In conclusion, PMS can be considered as a novel oxidant that provides an effective approach for selectively floating chalcopyrite and galena.

Study on law and influencing factors of air leakage in isolated island working face with large burial depth

Wang Gang, Xia Mingze, Xie Shuliang, Xu Hao, Wang Shuxin, Deng Xintai

Journal of Sustainable Mining

2024

Vol. 23, iss. 3

315--326

During the mining of a single coal seam isolated island work surface with large burial depth, the high mine pressures can crush and break the protective coal pillars, causing serious air leakages in the rear goaf. Herein, we use the analytic hierarchy process(AHP) to determine the main influencing factors of air leakage in island mining face. The air leakage source and sink in goaf were determined by measuring the differential pressures between the island mining face and the adjacent goaf using the energy level measurement method. The air volumes in the roadways were monitored on site to quantitatively analyze the specific changes of the air leakage in the isolated island work surface. Finally, the air leakage prevention measures were evaluated for the air leakage reduction efficiency in the island mining face and the goaf. Research shows that: (1) The fissure development in the roadway wall is the main influencing element of the air leakage in the isolated island work surface; (2) The differential pressure causes the air leakage volume of 37-40 m3/ min from the goaf to the island mining face; (3) Shotcrete in the gob-side roadway of the isolated island work surface can reduce the air leakage by 78%.

The Influence of Short-Term High Temperature Environment on the Non-Uniform Distribution of Ferrite Grain Size in 40 mm-thick Q345 Steel

Xu Hao, Gou Rui-Bin, Yu Min, Dan Wen-Jiao, Wang Nian

Archives of Metallurgy and Materials

2024

Vol. 69, iss. 1

197--208

In order to reveal the non-uniform distribution of grain size in thick direction for engineering heavy plate, microstructure of 40 mm-thick Q345 steel was observed and measured under different short-term high temperature environments formed by fire. Moreover, the influence of the short-term high temperature environment was revealed on the distribution of ferrite grain size in the Q345 steel. Under different fire service environments, there was a log-normal distribution relationship between the distribution parameter Nf (number of ferrite grains) and df (average grain diameter), as well as ρAf (area fraction density) and df, at different positions along the thickness direction. However, the statistical results are greatly affected by the length of the statistical interval. When df is about 4 to 6 times the length of the statistical interval, the statistical accuracy is higher. By using nonlinear fitting method, multiple non-uniform distribution empirical models including Nf-df empirical formulas and ρAf-df empirical formulas were established at different positions along thick direction under various fire environments. Furthermore, the interrelationships between fire temperature T and Nf, T and ρAf, fire duration t and Nf, t and ρAf were revealed, respectively.