Flocculation and settling behavior of unclassified tailings based on measurement of floc chord length
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摘要: 基于全尾砂絮凝過程中絮團弦長的測定，分別研究絮凝和沉降兩個過程：首先以絮團平均弦長為指標研究不同絮凝條件下全尾砂絮凝行為，再以固液界面初始沉降速率為指標分析不同絮凝全尾砂料漿的沉降行為。探明了不同絮凝條件下全尾砂尺寸演化規律，全尾砂均快速絮凝形成絮團，絮團的平均弦長增長達到峰值后隨著剪切時間逐漸下降，直至達到穩定狀態。發現全尾砂絮團的平均弦長與絮凝全尾砂料漿固液界面的初始沉降速率隨著不同的絮凝條件而不斷改變，確定了在本文研究范圍內的最優絮凝條件：Magnafloc 5250絮凝劑，全尾砂料漿固相質量分數10%，絮凝劑單耗10 g·t?1，絮凝劑溶液中絮凝劑質量分數0.025%，剪切速率94.8 s?1。最優條件下絮凝過程中絮團平均弦長峰值為620.63 μm，絮凝結束時絮團平均弦長為399.57 μm，絮凝全尾砂料漿固液界面初始沉降速率為4.61 mm·s?1。初步建立了適用于本文全尾砂的基于絮團平均弦長的固液界面初始沉降速率模型，固液界面初始沉降速率隨著絮團平均弦長的增加而增加，為實際生產中控制全尾砂絮凝沉降參數以及設備結構優化、提高全尾砂料漿的絮凝沉降效率提供參考。
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關鍵詞:
- 全尾砂 /
- 絮團弦長 /
- 聚焦式激光反射測量系統 /
- 剪切速率 /
- 固液界面初始沉降速率
Abstract: Deep-cone thickening of unclassified tailings is one of the key technologies in the field of cemented paste backfill. Flocculation and settling behavior of unclassified tailings constitute key research topics of the deep-cone thickening technology. Based on the measurement of the floc chord length during the unclassified tailings flocculation process, this study investigated the flocculation and settling processes independently, which is different from the traditional research. First, the average chord length of the floc was used as the index to study the flocculation behavior of the unclassified tailings under different conditions. Then, the initial settling rate of the suspension–supernate interface was used as the index to analyze the settling behavior of the unclassified tailings slurry under varying flocculation conditions. Under different flocculation conditions, the unclassified tailings particles were flocculated rapidly and the average chord length of the floc increased rapidly to the peak value. Then, it decreased gradually with the shear time until it reached a stable state. It was found that the average chord length of the flocs of the unclassified tailings and the initial settling rate of the suspension–supernate interface of the flocculated, unclassified tailings slurry vary with flocculation conditions. For the scope of this study, the optimal flocculation conditions were determined as follows: the flocculant used was Magnafloc 5250, the solid mass fraction was 10%, the flocculant dosage was 10 g·t?1, the flocculant mass fraction was 0.025%, and the shear rate was 94.8 s?1. Under such flocculation conditions, the peak value of the average chord length of the floc was 620.63 μm, the average chord length after the flocculation was 399.57 μm, and the initial settling rate of the suspension–supernate interface of the flocculated tailings slurry was 4.61 mm·s?1. The initial settling rate model of the suspension–supernate interface, applicable only to the tailings used in this study, was established preliminarily based on the average chord length of the flocs. The initial settling rate of the suspension–supernate interface increased with the increase in the average chord length of the flocs, providing a reference for the control of flocculation and settling parameters and the optimization of the equipment structure to improve the flocculation settling efficiency of unclassified tailings slurry in actual production. -
圖 3 FBRM探頭結構示意和弦長測試原理
Figure 3. Schematic of FBRM probe structure and chord length measuring principle
圖 5 Magnafloc 5250作用下全尾砂絮團弦長分布（CD為累積分布，DD為微分分布）
Figure 5. Chord length distribution of unclassified tailings floc using Magnafloc 5250 (CD and DD are abbreviations for cumulative distribution and differential distribution, respectively)
圖 6 不同絮凝劑種類條件下絮凝全尾砂料漿沉降曲線
Figure 6. Settling curve of flocculated tailings slurry under different flocculants
圖 7 不同固相質量分數條件下全尾砂絮凝行為
Figure 7. Flocculation behavior under different solid mass fractions
圖 8 不同固相質量分數條件下絮凝全尾砂料漿沉降曲線
Figure 8. Settling curves of flocculated tailings slurry under different solid mass fractions
圖 9 不同絮凝劑單耗（a）與絮凝劑質量分數（b）條件下全尾砂絮凝行為
Figure 9. Flocculation behavior under different flocculant dosages (a) and flocculant mass fractions (b)
圖 10 不同絮凝劑單耗（a）與絮凝劑質量分數（b）條件下絮凝全尾砂料漿沉降曲線
Figure 10. Settling curves of flocculated tailings slurry under different flocculant dosages (a) and flocculant mass fractions (b)
圖 12 不同剪切速率條件下絮凝全尾砂料漿沉降曲線
Figure 12. Settling curves of flocculated tailings slurry under different shear rates
圖 13 固液界面初始沉降速率與絮團弦長的關系
Figure 13. Relationship between suspension–supernate interface initial settling rate and floc chord length
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