Effects of ore size distribution on the pore structure characteristics of packed ore beds
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摘要: 為研究堆浸體系礦石粒徑分布對孔隙結構的影響，對不同級配礦巖散體構成的浸柱開展顯微CT掃描測試，得到浸柱內部結構圖像。通過閾值分割算法對孔隙結構進行提取，建立浸柱三維孔隙模型，對浸柱體孔隙率和面孔隙率的空間分布特征進行研究。利用最大球算法構建浸柱孔隙網絡模型，進而分析礦石粒徑分布對孔喉半徑、喉道長度、孔喉體積、形狀因子和配位數等參數的影響規律。結果表明：礦石顆粒級配性越好，礦堆孔隙率越低；礦石粒徑越均勻，礦堆不同區域孔隙率差異越小；礦石粒徑分布對孔隙尺寸和連通性影響較為顯著，對孔喉形狀因子影響較小。隨著細顆粒礦石的減少，大孔隙增多，孔喉半徑、喉道長度和孔喉體積相應增大；隨著礦石粒徑均勻性的增加，堆浸體系中孤立孔隙所占比例減少，高配位數孔隙所占比例增大，即礦堆內的孔隙空間具有更好的連通性。Abstract: Heap leaching is a widely used solution mining technology that enables various kinds of low-grade ores to be processed economically. The solution flow characteristics are very important factors in the leaching process, and they influence both the overall recovery and kinetics of the system. The properties of fluid flow in porous media are associated with the pore structure, which is influenced by the grain size and shape. To study the influence of ore particle size gradation on the pore structure of the heap leaching system, a micro-CT scanning test was conducted in ore columns with two grain size gradation types, and images of the internal structure of the leaching columns were obtained. A 3D digital pore model of the two leaching columns was then established, and the spatial distribution characteristics of 2D and 3D porosity were analyzed. The pore network models of the two columns were then extracted from the reconstructed 3D binary pore structures using the maximal ball fitting method, and the effect of the ore particle size distribution on the pore throat radius, throat length, pore throat volume, shape factor, and coordination number was analyzed. The results show that the porosity of the column comprising well-graded ore particles is lower than the column with uniformly graded grains. In addition, the 2D and 3D porosities of the well-graded ores show a relatively high degree of heterogeneity compared to those of the more uniformly graded ores. The ore particle size gradation has a significant influence on pore size and pore connectivity, but it has a minimal influence on the pore throat shape factor. The number of large pores increases with a decrease in the amount of fine ore, and the pore throat radius, throat length, and pore throat volume also correspondingly increase. When the uniformity of ore particle gradation is enhanced, the proportion of isolated pores decreases and the proportion of the number of high coordination pores increases.
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Key words:
- heap leaching system /
- ore size distribution /
- micro CT /
- 3D pore structure /
- pore network model
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圖 3 浸柱三維圖像。（a）浸柱A；（b）浸柱B
Figure 3. 3D reconstructed ore columns: (a) column A; (b) column B
圖 4 浸柱三維孔隙結構圖像。（a）浸柱A；（b）浸柱B
Figure 4. 3D pore image of ore columns: (a) column A; (b) column B
圖 7 面孔隙率隨浸柱高度變化曲線
Figure 7. Distribution of 2D porosity along ore column height direction
圖 8 相對面孔隙率隨浸柱高度變化曲線
Figure 8. Distribution of relative 2D porosity along ore column height direction
圖 9 浸柱孔隙網絡模型。（a）浸柱A；（b）浸柱B
Figure 9. Pore network model of ore columns: (a) column A; (b) column B
圖 10 孔喉半徑分布曲線。（a）孔隙；（b）喉道
Figure 10. Frequency distribution of radius: (a) pore; (b) throat
圖 12 孔喉體積分布曲線。（a）孔隙；（b）喉道
Figure 12. Frequency distribution of pore volume: (a) pore; (b) throat
圖 13 孔喉形狀因子分布曲線。（a）孔隙；（b）喉道
Figure 13. Frequency distribution of shape factor: (a) pore; (b) throat
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