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Cheng Wang
Cheng Wang
Master, Master of Mineral Processing Engineering
China University of Mining and Technology School of Chemical Engineering
Master, Master of Mineral Processing Engineering
China University of Mining and Technology School of Chemical Engineering
Xuzhou
China

Articles

Geotechnical Engineering and Engineering Geology
  • Date submitted
    2023-01-16
  • Date accepted
    2023-06-20
  • Online publication date
    2024-02-05
  • Date published
    2024-04-25

Study on the thin layer drying and diffusion mechanism of low rank coal in Inner Mongolia and Yunnan

Article preview

Coal is one of the world's most important energy substances. China is rich in coal resources, accounting for more than 90 % of all ascertained fossil energy reserves. The consumption share of coal energy reaches 56.5 % in 2021. Due to the high moisture content of low-rank coal, it is easy to cause equipment blockage in the dry sorting process. This paper considers low-rank coal coming from Inner Mongolia (NM samples) and Yunnan (YN samples). The weight loss performance of the samples was analyzed using thermogravimetric experiments to determine the appropriate temperature for drying experiments. Thin-layer drying experiments were carried out at different temperature conditions. The drying characteristics of low-rank coal were that the higher the drying temperature, the shorter the drying completion time; the smaller the particle size, the shorter the drying completion time. The effective moisture diffusion coefficient was fitted using the Arrhenius equation. The effective water diffusion coefficient of NM samples was 5.07·10–11 - 9.58·10–11 m2/s. The effective water diffusion coefficients of the three different particle sizes of YN samples were 1.89·10–11 - 4.92·10–11 (–1 mm), 1.38·10–10 - 4.13·10–10 (1-3 mm), 5.26·10–10 - 1.49·10–9 (3-6 mm). The activation energy of Inner Mongolia lignite was 10.97 kJ/mol (–1 mm). The activation energies of Yunnan lignite with different particle sizes were 17.97 kJ/mol (–1 mm), 33.52 kJ/mol (1-3 mm), and 38.64 kJ/mol (3-6 mm). The drying process was simulated using empirical and semi-empirical formulas. The optimal model for Inner Mongolia samples was the Two-term diffusion model, and Yunnan samples were the Hii equation was used.

How to cite: Wang C., Wang D., Chen Z., Duan C., Zhou C. Study on the thin layer drying and diffusion mechanism of low rank coal in Inner Mongolia and Yunnan // Journal of Mining Institute. 2024. Vol. 266. p. 326-338. EDN XMIQWH
Metallurgy and concentration
  • Date submitted
    2020-06-10
  • Date accepted
    2020-11-19
  • Date published
    2021-04-21

Influence of jarosite precipitation on iron balance in heap bioleaching at Monywa copper mine

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Ferric iron is an important oxidant in sulfide ore bioleaching. However, recirculating leach liquors leads to excess iron accumulation, which interferes with leaching kinetics and downstream metal recovery. We developed a method for controlling iron precipitation as jarosite to reduce excess iron in heap bioleaching at Monywa copper mine. Jarosite precipitation was first simulated and then confirmed using batch column tests. From the simulations, the minimum pH values for precipitation of potassium jarosite, hydronium jarosite, and natrojarosite at 25 °C are 1.4, 1.6, and 2.7, respectively; the minimum concentrations of potassium, sulfate, ferric, and sodium ions are 1 mM, 0.54, 1.1, and 3.2 M, respectively, at 25 °C and pH 1.23. Column tests indicate that potassium jarosite precipitation is preferential over natrojarosite. Moreover, decreased acidity (from 12 to 8 g/L), increased temperature (from 30 to 60 °C), and increased potassium ion concentration (from 0 to 5 g/L) increase jarosite precipitation efficiency by 10, 5, and 6 times, respectively. Jarosite precipitation is optimized by increasing the irrigating solution pH to 1.6. This approach is expected to reduce the operating cost of heap bioleaching by minimizing the chemicals needed for neutralization, avoiding the need for tailing pond construction, and increasing copper recovery.

How to cite: Soe K.M., Ruan R., Jia Y., Tan Q., Wang Z., Shi J., Zhong C., Sun H. Influence of jarosite precipitation on iron balance in heap bioleaching at Monywa copper mine // Journal of Mining Institute. 2021. Vol. 247. p. 102-113. DOI: 10.31897/PMI.2020.1.11