Regulation and a mathematical model of underflow in paste thickeners based on a circular system design
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摘要: 為了保證濃密機在高料位下不壓耙,一般通過增設循環系統使料漿始終處于活化狀態,降低耙架運行阻力.然而,目前循環參數對底流的影響規律不明確,造成系統的設計及應用缺乏科學依據,為此開展了循環參數對底流的調控研究.分析循環系統的作用原理,將循環系統作用范圍劃分為兩大區域,揭示循環參數對底流的調控機制,運用微積分原理對區域內的底流體積分數變化進行求解,最終建立濃密機底流調控數學模型.最后,利用該模型對底流循環實驗參數進行驗證.研究結果表明:開啟底流循環后,底流體積分數開始降低并最終趨于穩定,底流體積分數差隨著循環流量及循環高度增大而增大,體積分數變化幅度為0.7%~2.2%,穩定所需時間隨流量及高度增加而減小.該理論模型完全吻合驗證結果函數,為循環系統的設計及運行提供理論依據.Abstract: To assure that compression on the rakes of a deep corn thickener does not stop mixing, an additional circular slurry system, which activates slurry all the time, is employed and running resistance is usually decreased. However, there is still uncertainty on how circular parameters affect underflow properties. This means that the design and application of such systems lack support from scientific theories. Hence, it is necessary to create a study on how circular parameters regulate underflow parameters. Analysis of the circular system mechanism shows that its effect can be divided into two parts and the effect of the system on underflow properties is clarified. In addition, the value of underflow concentration in thickeners is solved based on calculus and finally a mathematical model is produced, which simulates the regulation of underflow properties in thickeners. Using the model, the circular parameters of underflow in thickeners are verified. The experiment indicates that the solid concentration of underflow decreases with circular underflow initiation, then tends to stabilize. Also, the volume fraction of underflow increases in the range of 0.7% -2.2% with ascending circular flow and height. In addition, the time necessary for the solid concentration to stabilize is reversely affected by underflow flow and height. The regression function obtained from experimental statistics shows excellent performance in the model when designing and analyzing circular systems for thickeners.
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Key words:
- thickener /
- underflow /
- regulation mechanism /
- circular parameters /
- mathematical model
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參考文獻
[4] Reid C, Bécaert V, Aubertin M, et al. Life cycle assessment of mine tailings management in Canada. J Clean Prod, 2009, 17(4):471 [10] Banfill P F G. The rheology of fresh mortar. Mag Concrete Res, 1991, 43(154):13 [11] Huynh L, Beattie D A, Fornasiero D, et al. Effect of polyphosphate and naphthalene sulfonate formaldehyde condensate on the rheological properties of dewatered tailings and cemented paste backfill. Miner Eng, 2006, 19(1):28 [12] Mangiafico S, Sauzéat C, Di Benedetto H, et al. Quantification of biasing effects during fatigue tests on asphalt mixes:non-linearity, self-heating and thixotropy. Road Mater Pavement Des, 2015, 16(Suppl 2):73 [13] Coussot P, Nguyen Q D, Huynh H T, et al. Avalanche behavior in yield stress fluids. Phys Rev Lett, 2002, 88(17):175501 [14] Roussel N, Le Roy R, Coussot P. Thixotropy modelling at local and macroscopic scales. J Non-Newton Fluid Mech, 2004, 117(2-3):85 [16] Díaz-Zorita M. Effect of deep-tillage and nitrogen fertilization interactions on dryland corn (Zea mays L.) productivity. Soil Till Res, 2000, 54(1-2):11 [17] Li S, Wang X M. Fly-ash-based magnetic coagulant for rapid sedimentation of electronegative slimes and ultrafine tailings. Powder Technol, 2016, 303:20 [18] Zhou Z W, Scales P J, Boger D V. Chemical and physical control of the rheology of concentrated metal oxide suspensions. Chem Eng Sci, 2001, 56(9):2901 -
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