Changes in underflow solid fraction and yield stress in paste thickeners by circulation


The trouble-free and efficient operation of paste thickeners requires an optimal design and the cooperation of each component. When underflow discharging is suspended, alleviating the vast torque that the remaining solids within the thickeners may place on rakes mainly lies in the circulation unit. The mechanism of this unit was analyzed, and a mathematical model was developed to describe the changes in underflow solid content and yield stress. The key parameters of the circulation unit, namely, the height and flow rate, were varied to test its performance in the experiments with a self-designed laboratorial thickening system. Results show that the circulation unit is valid in reducing underflow solid fraction and yield stress to a reasonable extent, and the model could be used to describe its efficiency at different heights and flow rates. A suitable design and application of the circulation unit contributes to a cost-effective operation of paste thickeners.

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  1. [1]

    S.C. Pan, C.C. Lin, and D.H. Tseng, Reusing sewage sludge ash as adsorbent for copper removal from wastewater, Resour. Conserv. Recycl., 39(2003), No. 1, p. 79.

    Article  Google Scholar 

  2. [2]

    F. Concha and R. Bürger, Thickening in the 20th century: A historical perspective, Min. Metall. Explor., 20(2003), No. 2, p. 57.

    CAS  Google Scholar 

  3. [3]

    H.Z. Jiao, S.F. Wang, Y.X. Yang, and X.M. Chen, Water recovery improvement by shearing of gravity-thickened tailings for cemented paste backfill, J. Cleaner Prod., 245(2020), art. No. 118882.

  4. [4]

    D.L. Wang, Q.L. Zhang, Q.S. Chen, C.C. Qi, Y. Feng, and C.C. Xiao, Temperature variation characteristics in flocculation settlement of tailings and its mechanism, Int. J. Miner. Metall. Mater., 27(2020), No. 11, p. 1438.

    Article  Google Scholar 

  5. [5]

    M. Benzaazoua, J. Ouellet, S. Servant, P. Newman, and R. Verburg, Cementitious backfill with high sulfur content physical, chemical, and mineralogical characterization, Cem. Concr. Res., 29(1999), No. 5, p. 719.

    CAS  Article  Google Scholar 

  6. [6]

    M. Fall and M. Benzaazoua, Modeling the effect of sulphate on strength development of paste backfill and binder mixture optimization, Cem. Concr. Res., 35(2005), No. 2, p. 301.

    CAS  Article  Google Scholar 

  7. [7]

    M. Benzaazoua, P. Marion, I. Picquet, and B. Bussière, The use of pastefill as a solidification and stabilization process for the control of acid mine drainage, Miner. Eng., 17(2004), No. 2, p. 233.

    CAS  Article  Google Scholar 

  8. [8]

    A.X. Wu, Y. Yang, H.Y. Cheng, S.M. Chen, and Y. Han, Status and prospects of paste technology in China, Chin. J. Eng., 40(2018), No. 5, p. 517.

    Google Scholar 

  9. [9]

    Y.X. Yang, T.Q. Zhao, H.Z. Jiao, Y.F. Wang, and H.Y. Li, Potential effect of porosity evolution of cemented paste backfill on selective solidification of heavy metal ions, Int. J. Environ. Res. Public Health, 17(2020), No. 3, p. 814.

    CAS  Article  Google Scholar 

  10. [10]

    M. Benzaazoua, M. Fall, and T. Belem, A contribution to understanding the hardening process of cemented pastefill, Miner. Eng., 17(2004), No. 2, p. 141.

    CAS  Article  Google Scholar 

  11. [11]

    M. Pokharel and M. Fall, Combined influence of sulphate and temperature on the saturated hydraulic conductivity of hardened cemented paste backfill, Cem. Concr. Compos., 38(2013), p. 21.

    CAS  Article  Google Scholar 

  12. [12]

    H.Z. Jiao, S.F. Wang, A.X. Wu, H.M. Shen, and J.D. Wang, Cementitious property of NaAlO2-activated Ge slag as cement supplement, Int. J. Miner. Metall. Mater., 26(2019), No. 12, p. 1594.

    CAS  Article  Google Scholar 

  13. [13]

    C.C. Qi and A. Fourie, Cemented paste backfill for mineral tailings management: Review and future perspectives, Miner. Eng., 144(2019), art. No. 106025.

  14. [14]

    X. Zhao, A. Fourie, and C.C. Qi, Mechanics and safety issues in tailing-based backfill: A review, Int. J. Miner. Metall. Mater., 27(2020), No. 9, p. 1165.

    Article  Google Scholar 

  15. [15]

    D.V. Boger, Rheology and the resource industries, Chem. Eng. Sci., 64(2009), No. 22, p. 4525.

    CAS  Article  Google Scholar 

  16. [16]

    S.P. Usher, Suspension Dewatering: Characterisation and Optimisation [Dissertation], University of Melbourne, Victoria, 2002, p. 20.

    Google Scholar 

  17. [17]

    T. Belem and M. Benzaazoua, Design and application of underground mine paste backfill technology, Geotech. Geol. Eng., 26(2008), No. 2, p. 147.

    Article  Google Scholar 

  18. [18]

    T. Meggyes and A. Debreczeni, Paste technology for tailings management, Land Contam. Reclam., 14(2006), No. 4, p. 815.

    Article  Google Scholar 

  19. [19]

    R.J. Jewell and A.B. Fourie, Paste and Thickened Tailings—A Guide, 3rd ed, Australian Centre for Geomechanics, Western Australia, 2015.

  20. [20]

    M.C. Mulligan and L. Bradford, Soluble metal recovery improvement using high density thickeners in a CCD circuit: Ruashi II case study, J. South Afr. Inst. Min. Metall., 109(2009), No. 11, p. 665.

    CAS  Google Scholar 

  21. [21]

    F.W. Brackebusch, Basics of paste backfill systems, Int. J. Rock Mech. Min. Sci. Geomech. Abstr., 32(1995), No. 3, p. 122A.

    Google Scholar 

  22. [22]

    S.P. Usher and P.J. Scales, Steady state thickener modelling from the compressive yield stress and hindered settling function, Chem. Eng. J., 111(2005), No. 2–3, p. 253.

    CAS  Article  Google Scholar 

  23. [23]

    Y. Wang, A.X. Wu, Z.E. Ruan, Z.H. Wang, Z.S. Wei, G.F. Yang, and Y.M. Wang, Reconstructed rheometer for direct monitoring of dewatering performance and torque in tailings thickening process, Int. J. Miner. Metall. Mater., 27(2020), No. 11, pp. 1430–1437.

    Article  Google Scholar 

  24. [24]

    K.A. Landman, L.R. White, and R. Buscall, The continuous-flow gravity thickener: Steady state behavior, AIChE J., 34(1988), No. 2, p. 239.

    CAS  Article  Google Scholar 

  25. [25]

    H.J. Wang, X. Zhou, A.X. Wu, Y.M. Wang, and L.H. Yang, Mathematical model and factors of paste thickener rake torque, Chin. J. Eng., 40(2018), No. 6, p. 673.

    Google Scholar 

  26. [26]

    H.Z. Jiao, Research on the Tailings Flocs Behavior and Dewatering Mechanism in Deep Cone Thickening [Dissertation], University of Science and Technology Beijing, Beijing, 2014, p. 67.

    Google Scholar 

  27. [27]

    M. Rudman, D.A. Paterson, and K. Simic, Efficiency of raking in gravity thickeners, Int. J. Miner. Process., 95(2010), No. 1–4, p. 30.

    CAS  Article  Google Scholar 

  28. [28]

    M. Rudman, K. Simic, D.A. Paterson, P. Strode, A. Brent, and I.D. Šutalo, Raking in gravity thickeners, Int. J. Miner. Process., 86(2008), No. 1–4, p. 114.

    CAS  Article  Google Scholar 

  29. [29]

    C.K. Tan, J. Bao, and G. Bickert, A study on model predictive control in paste thickeners with rake torque constraint, Miner. Eng., 105(2017), p. 52.

    CAS  Article  Google Scholar 

  30. [30]

    L.H. Yang, H.J. Wang, A.X. Wu, L.F. Zhang, and H. Chen, Regulation and a mathematical model of underflow in paste thickeners based on a circular system design, Chin. J. Eng., 39(2017), No. 10, p. 1507.

    Google Scholar 

  31. [31]

    S.P. Usher, R. Spehar, and P.J. Scales, Theoretical analysis of aggregate densification: Impact on thickener performance, Chem. Eng. J., 151(2009), No. 1–3, p. 202.

    CAS  Article  Google Scholar 

  32. [32]

    W.F. Eckert, J.H. Masliyah, M.R. Gray, and P.M. Fedorak, Prediction of sedimentation and consolidation of fine tails, AIChE J., 42(1996), No. 4, p. 960.

    CAS  Article  Google Scholar 

  33. [33]

    S. Azam, S. Jeeravipoolvarn, and J.D. Scott, Numerical modeling of tailings thickening for improved mine waste management, J. Environ. Inf., 13(2009), No. 2, p. 111.

    Article  Google Scholar 

  34. [34]

    H.Z. Jiao, A.X. Wu, H.J. Wang, S.P. Zhong, R.M. Ruan, and S.H. Yin, The solids concentration distribution in the deep cone thickener: A pilot scale test, Korean J. Chem. Eng., 30(2013), No. 2, p. 262.

    CAS  Article  Google Scholar 

  35. [35]

    S.K. Gawu and A.B. Fourie, Assessment of the modified slump test as a measure of the yield stress of high-density thickened tailings, Can. Geotech. J., 41(2004), No. 1, p. 39.

    CAS  Article  Google Scholar 

  36. [36]

    Q.D. Nguyen and D.V. Boger, Application of rheology to solving tailings disposal problems, Int. J. Miner. Process., 54(1998), No. 3–4, p. 217.

    CAS  Article  Google Scholar 

  37. [37]

    A. Kesimal, E. Yilmaz, and B. Ercikdi, Evaluation of paste backfill mixtures consisting of sulphide-rich mill tailings and varying cement contents, Cem. Concr. Res., 34(2004), No. 10, p. 1817.

    CAS  Article  Google Scholar 

  38. [38]

    H.Y. Cheng, S.C. Wu, A.X. Wu, and W.H. Cheng, Grading characterization and yield stress prediction based on paste stability coefficient, Chin. J. Eng., 40(2018), No. 10, p. 1168.

    Google Scholar 

  39. [39]

    A. Kesimal, E. Yilmaz, B. Ercikdi, I. Alp, and H. Deveci, Effect of properties of tailings and binder on the short-and long-term strength and stability of cemented paste backfill, Mater. Lett., 59(2005), No. 28, p. 3703.

    CAS  Article  Google Scholar 

  40. [40]

    K. Terzaghi, R.B. Peck, and G. Mesri, Soil Mechanics in Engineering Practice, 3rd ed., John Wiley & Sons, Inc., New York, 1995.

    Google Scholar 

  41. [41]

    J.B. Farrow, R.R.M. Johnston, K. Simic, and J.D. Swift, Consolidation and aggregate densification during gravity thickening, Chem. Eng. J., 80(2000), No. 1–3, p. 141.

    CAS  Article  Google Scholar 

  42. [42]

    N.Q. Dzuy and D.V. Boger, Yield stress measurement for concentrated suspensions, J. Rheol., 27(1983), No. 4, p. 321.

    Article  Google Scholar 

  43. [43]

    H.Y. Cheng, S.C. Wu, H. Li, and X.Q. Zhang, Influence of time and temperature on rheology and flow performance of cemented paste backfill, Constr. Build. Mater., 231(2020), art. No. 117117.

  44. [44]

    X. Zhou, X.G. Jin, P.Z. Liu, H.P. Wu, and H.W. Li, Prediction model for underflow concentration of deep cone thickener based on dynamic thickening experimentation, Met. Mine, 12(2017), p. 39.

    Google Scholar 

  45. [45]

    X. Jin, Experimental study on influence factors on rheological properties of underflow in deep-cone thickeners, Mod. Min., 31(2015), No. 3, p. 201.

    Google Scholar 

  46. [46]

    M.H. Zhang, C.F. Ferraris, H. Zhu, V. Picandet, M.A. Peltz, P. Stutzman, and D.D. Kee, Measurement of yield stress for concentrated suspensions using a plate device, Mater. Struct., 43(2010), No. 1–2, p. 47.

    CAS  Article  Google Scholar 

  47. [47]

    J.E. Wallevik, Relationship between the Bingham parameters and slump, Cem. Concr. Res., 36(2006), No. 7, p. 1214.

    CAS  Article  Google Scholar 

  48. [48]

    S. Wang, X.P. Song, X.J. Wang, Q.S. Chen, J.C. Qin, and Y.X. Ke, Influence of coarse tailings on flocculation settlement, Int. J. Miner. Metall. Mater., 27(2020), No. 8, p. 1065.

    CAS  Article  Google Scholar 

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This work was financially supported by the National Natural Science Foundation of China (No. 51834001).

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Correspondence to Ai-xiang Wu.

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Li, H., Wu, Ax., Wang, HJ. et al. Changes in underflow solid fraction and yield stress in paste thickeners by circulation. Int J Miner Metall Mater (2021).

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  • paste thickener
  • circulation unit
  • solids content
  • yield stress
  • rake failure