NUST MISIS, Moscow, Russia:

A. A. Nikolaev, Associate Professor, Candidate of Engineering Sciences, nikolaevopr@mail.ru
G. K. Kairatova, Holder of a Master’s Degree
B. E. Goryachev, Professor, Doctor of Engineering Sciences

In the paper, the studies of coal slurry settling in water are presented. The experiments were carried out in graduated cylinders with a volume of 500 ml. Cationic, anionic and non-ionic reagents of Magnafloc series were used as flocculants. The effect of flocculants on the settling rate of coal slurry particles, solid content in the sediment and liquid purity of the clarified layer was studied. The purity of water was examined by means of photometric analysis. The results indicate that to achieve the purity of water in the clarified layer (light transmission T = 94÷94.5%), flocculants Magnafloc 10 or Magnafloc 380 are required at the consumption of about 50 g/t. The coal slurry settling time was 40 min. A moderately pure clarified layer can be obtained within a short settling time using Magnafloc 333 as flocculant. Small flocculant consumption (q ~ 1 g/t) for Magnafloc 10, 333, 336, 1011 or 345 revealed moderately pure (82.0–87.4 %) clarified layer. The findings show that an increase in the flocculant consumption results in a growth of settling rate and solid content of coal slurry. There was an insignificant decrease in the slurry solid content at the maximum settling rate when Magnafloc 345, 333 and 5250 were used. This may be due to formation of large flocs, which generate slurry of high porosity. Magnafloc 10 at a consumption of 50 g/t can be recommended as an anionic flocculant to achieve a high rate of thickening (2.6 cm/min) of coal slurry and to obtain slurry with a high content of solids (60 %) and a pure discharge of thickener.

1. Artyushin S. P. Coal preparation. Moscow : Nedra, 1975. 381 p.
2. Berinberg Z. Sh., Blagov I. S., Borts M. A. et al. Coal preparation manual. I. S. Blagov et al. (Eds.). 2^nd revised and enlarged edition. Moscow : Nedra, 1984. 614 p.
3. Antipenko L. A. Determination, statistics and control of coal loss in dressing. Ugol. 2010. No. 1. pp. 63–66.
4. Alekseev K. Yu., Linev B. I., Rubinshtein Yu. B. Current tendencies in coal dressing in the world. Ugol. 2011. No. 5. pp. 98–103.
5. Linev B. I., Rubinshtein Yu. B., Davydov M. V., Sazykin G. P. Improvement of coal-concentrating production in Russia. Gornyi Zhurnal. 2012. No. 8. pp. 8–14.
6. Yu Y., Ma L., Cao M., Liu Q. Slime coatings in froth flotation: a review. Minerals Engineering. 2017. Vol. 114. pp. 26–36.
7. Rubinstein Y. B., Linev B. I., Samoilova E. K. Improvement of the efficiency of fine coal slimes flotation. XVIII International Coal Preparation Congress. Springer, Cham. 2016. pp. 979–984.
8. Eremeev D. N. Clarification of slime water and thickening of coal slurry flotation tailings using polymeric flocculants. Voda : khimiya i ekologiya. 2012. Vol. 2(44). pp. 63–66.
9. Nevedrov A. V., Papin A. V., Solodov V. S. Ecological aspects of treatment of slime water from coal mines. Energy Security of Russia. New Approaches to Advancement of Coal Mining Industry: XV International Scientific and Practical Conference Proceedings. Kemerovo : FITS UUKH, SO RAN, 2013. pp. 187–188.
10. Concha F., Rulyov N. N., Laskowski J. S. Settling velocities of particulate systems 18: solid flux density determination by ultra-flocculation. International Journal of Mineral Processing. 2012. Vol. 104-105. pp. 53–57.
11. Grabsch A. F., Fawell P. D., Adkins S. J., Beveridge A. The impact of achieving a higher aggregate density on polymer-bridging flocculation. International Journal of Mineral Processing. 2013. Vol. 124. pp. 83–94.
12. Kumar S., Bhattacharya S., Mandre N. R. Characterization and flocculation studies of fine coal tailings. Journal of the Southern African Institute of Mining and Metallurgy. 2014. Vol. 114, No. 11. pp. 945–949.
13. Wang J., Fu X.-H., Hu E.-F., Zhao J., Feng Z.-Y., Wang H. Experimental study on flocculation flotation of ultra-clean coal from slime. Meitan Xuebao. 2015. Vol. 40. No. 8. pp. 1929–1935.
14. Rubinstein Yu. B., Novak V. I. Technology of flocculant separation of micronized coal slimes. Izvestiya vuzov. Gornyi zhurnal. 2011. No. 3. pp. 45–51.
15. Wei H., Gao B., Ren J., Li A., Yang H. Coagulation/flocculation in dewatering of sludge: A review. Water Research. 2018. Vol. 143. pp. 608–631.
16. Moyakhe D. M., Campbell Q. P., Fosso-Kankeu E. The Effect of Flocculant Type on Settling Properties of Fine Coal Tailings. The 9^th International Conference on Advances in Science, Engineering, Technology & Waste Management (ASETWM-17). Parys, South Africa. 2017. pp. 165–168.
17. Bulatov M. I., Kalinkin I. P. Practical guidance on photometric analysis techniques. Leningrad : Khimiya, 1986. 432 p.
18. Mining Solutions. BASF. Available at: http://www.mining-solutions.basf.com (accessed: 26.07.2019).
19. Nikolaev A. A., Nikolaeva N. S., Yushina T. I. Auxiliary processes: laboratory-based practical. Moscow : MISIS, 2019. 47 p.