剪切濃密床層孔隙網絡模型與導水通道演化

焦華喆; 王樹飛; 吳愛祥; 沈慧明; 楊亦軒; 阮竹恩

doi:10.13374/j.issn2095-9389.2019.08.004

剪切濃密床層孔隙網絡模型與導水通道演化

doi: 10.13374/j.issn2095-9389.2019.08.004

1.
河南理工大學土木工程學院, 焦作 454000
2.
北京科技大學土木與資源工程學院, 北京 100083
3.
河南理工大學資源環境學院, 焦作 454000

基金項目:

國家自然科學基金資助項目 51704094

國家自然科學基金資助項目 51834001

國家自然科學基金資助項目 51574013

河南省高等學校重點科研項目 16A440003

國家安全生產重大事故防治關鍵技術項目 henan-0005-2016AQ

詳細信息

通訊作者:
楊亦軒, E-mail: yangyixuan@hpu.edu.cn

中圖分類號: TD853
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- 被引次數: 0
出版歷程
- 收稿日期: 2018-10-03
- 刊出日期: 2019-08-01

Pore network model of tailings thickener bed and water drainage channel evolution under the shearing effect

1.
School of Civil Engineering, Henan Polytechnic University, Jiaozuo 454000, China
2.
School of Civil and Resources Engineering, University of Science and Technology Beijing, Beijing 100083, China
3.
School of Resources and Environment, Henan Polytechnic University, Jiaozuo 454000, China

More Information

Corresponding author: YANG Yi-xuan, E-mail: yangyixuan@hpu.edu.cn

摘要

摘要: 剪切作用是膏體重力濃密制備的基礎要素, 本文研究了濃密床層孔隙和喉道的變化對導水通道的影響, 揭示了水分排出的來源與比例. 開展半工業實驗并結合計算機斷層掃描(CT)與孔隙網絡模型(PNM)提取床層微觀孔隙結構, 利用最大球搜索算法識別并分析剪切前后孔隙與喉道的演化規律. 結果表明, 添加轉速為2 r·min^-1的剪切作用將尾砂底流濃度(即底流的固相質量分數)由55.8%提升到58.5%, 孔隙率由43.05%降低到36.59%, 孔隙率降低的比率為15%. 通過PNM技術將孔隙空間劃分為"球體"儲水孔隙與"棍體"喉道; 剪切后球體和棍體數量分別增加了16.5%和22%, 球體平均尺寸小幅下降, 球體半徑多集中在40~60 μm之間. 棍體平均半徑由9.83 μm降低至8.58 μm, 降低了12.7%, 棍體長度變化較小. 剪切作用下的球體配位數在5~10的部分從25.73%增加至44.58%, 配位明顯增多, 顆粒接觸緊密. 本文提出"球棍比"的概念用于孔隙結構的定量表征. 剪切后球體體積占比由14.14%降低至12.75%, 球體體積減少的比率達到9.83%;棍的體積由28.91%降低至23.84%, 棍體積減少的比率為17.54%. 球棍比由48.91%增加至53.48%, 球棍比提升的比率達到了9.34%, 與球體體積減小相比, 棍的體積減少的幅度更大, 導致球棍比上升. 本文從孔隙結構變化的角度揭示了全尾砂重力濃密剪切排水機理; 剪排水過程中主要排出的是喉道中的水分, 孔隙中的水分排出較少.
- 膏體充填 /
- 重力濃密 /
- 剪切作用 /
- 孔隙率 /
- 導水通道 /
- 球棍比
Abstract: Shearing is the basic factor involved in gravity thickening of paste. This work focuses on the influence of pores and throats characteristics on water drainage channel evolution, and determines the proportion of discharged water in tailings thickener bed. Pilot-scale experiment combined with computed tomography (CT) and pore network model (PNM) technology to determine the micropore structure. The maximum ball algorithm is used to analyze the evolution of pores and throats with and without shearing. The results show that the tailings underflow concentration increases from 55.8% to 58.5% under 2 r·min^-1 rake shearing and the porosity decreases from 43.05% to 36.59%, the decrease rate of porosity is 15%. The pore structure can be divided into two types, i.e., "balls" and "sticks, " by the PNM technology. The quantity of "balls" and "sticks" increases by 16.5% and 22%, respectively. However, the average radius of balls decreases slightly in the range of 40-60 μm under shearing. The average radius of sticks decreases from 9.83 μm to 8.58 μm, i.e., by 12.7%. Nevertheless, the length of sticks exhibits only a slight change. The coordination number of balls increases significantly from 25.73% to 44.58% in the range of 5-10 under shearing, and the particles are in close contact. The concept of "the volume ratio of pores to balls" is proposed for the quantitative characterization of the pore structure. The volume fraction of balls decreases from 14.14% to 12.75%, the decrease rate of volume fraction is 9.83%, and volume fraction of sticks decreases from 28.91% to 23.84%, the decrease rate of volume fraction is 17.54%. The volume ratio of balls to sticks increases from 48.91% to 53.48%, and increase rate of it is 9.34%. When the volume decrease of balls is more than that of sticks, the volume ratio of balls to sticks increases. This work reveals the shearing drainage mechanism of unclassified tailings gravity thickening from the perspective of pore structure change, i.e., the drainage is mainly discharged from the throat more than the pore from the tailings thickener bed shear dewatering process.
- paste filling /
- gravity thickening /
- shearing /
- porosity /
- water drainage channel /
- volume ratio of ball to stick

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圖 1 全尾砂粒度分布曲線

Figure 1. Grain size distribution curve of unclassified tailings

下載: 全尺寸圖片幻燈片

圖 2 實驗裝置示意圖及樣品制備過程.(a) 半工業連續濃密實驗平臺; (b) 樣品制備過程

Figure 2. Schematic diagram of the experimental device and sample preparation process: (a)pilot-scale experimental platform of continuous thickening; (b) sample preparation process

下載: 全尺寸圖片幻燈片

圖 3 未凍脹孔隙計算示意圖

Figure 3. Schematic diagram of the calculation of pores without frost heaving

下載: 全尺寸圖片幻燈片

圖 4 孔隙網絡提取. (a) 圖像截取; (b) 中值濾波; (c) 圖像二值化; (d) 三維重構; (e) 連通孔隙劃分; (f) 孔隙網絡模型(PNM)建立

Figure 4. Pore network extraction: (a) image crop; (b) median filter; (c) binarization; (d) 3D reconstruction; (e) division of connected pores; (f) establishment of the pore network model (PNM)

下載: 全尺寸圖片幻燈片

圖 5 孔隙-喉道結構示意圖

Figure 5. Schematic diagram of the pore-throat structure

下載: 全尺寸圖片幻燈片

圖 6 膨脹搜索示意圖. (a) 側線, 6個方向; (b) 側線加對角線18個方向; (c) 側線、對角線加直徑線26個方向

Figure 6. Schematic diagram of the expansion search: (a) lateral line, 6 directions; (b) lateral line and diagonal, 18 directions; (c) lateral line, diagonal, and diameter line, 26 directions

下載: 全尺寸圖片幻燈片

圖 7 最大球被多個球包含的示意圖

Figure 7. Schematic diagram of the maximum ball contained within multiple balls

下載: 全尺寸圖片幻燈片

圖 8 PNM示意圖. (a) 剪切作用下的PNM; (b) 無剪切作用下的PNM

Figure 8. Schematic diagram of the PNM: (a) PNM with shearing; (b) PNM without shearing

下載: 全尺寸圖片幻燈片

圖 9 有/無剪切作用下球體半徑對比

Figure 9. Comparison of ball radius with and without shearing

下載: 全尺寸圖片幻燈片

圖 10 有/無剪切作用下棍體半徑對比與棍體長度對比. (a) 棍體半徑; (b) 棍體長度

Figure 10. Comparison of stick radius and stick length with and without shearing: (a) stick radius; (b) stick length

下載: 全尺寸圖片幻燈片

圖 11 球體配位數對比

Figure 11. Comparison of sphere coordination numbers

下載: 全尺寸圖片幻燈片

圖 12 剪切作用下PNM與導水通道結構演化示意圖. (a) PNM演化示意圖; (b) 導水通道結構演化示意圖

Figure 12. Schematic diagrams of the PNM and water drainage channel evolution with shearing: (a) schematic diagrams of the evolution of PNM; (b) schematic diagrams of water drainage channel evolution

下載: 全尺寸圖片幻燈片

圖 13 有/無剪切作用下喉道變化示意圖. (a) 剪切作用下孔隙喉道示意圖; (b) 無剪切作用下孔隙喉道示意圖

Figure 13. Schematic diagrams of the evolution of throats with and without shearing: (a) schematic diagrams of throats with shearing; (b) schematic diagrams of throats without shearing

下載: 全尺寸圖片幻燈片

表 1 有/無剪切作用下PNM參數對比

Table 1. Comparison of pore network model parameters with and without shearing

試驗條件	模型尺寸/(mm×mm×mm)	孔隙率/%	孔隙數量	吼道數量
無剪切	2×2×1	43.05	206	827
有剪切	2×2×1	36.59	240	1009

下載: 導出CSV

表 2 不同濃度下的屈服應力與指數m值

Table 2. Yield stress and index m under different concentrations

料漿濃度(料漿固相質量分數)/%	屈服應力/Pa	指數m值
50	24.01	2.7296
55	30.55	2.1391
60	41.71	0.552
65	75.62	0.3717
70	129.65	1.2251
75	214.93	1.0164

下載: 導出CSV

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