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Gold Science and Technology ›› 2022, Vol. 30 ›› Issue (1): 54-63.doi: 10.11872/j.issn.1005-2518.2022.01.092

• Mining Technology and Mine Management • Previous Articles     Next Articles

Study on Consolidation Characteristics of Tailings with Different Moisture Content Under Dry-Wet Cycle

Zhonghui WANG1(),Qianfu WANG1,Yakun TIAN1,2,Lingling WU1,2,Xueyang YU1,Zhijun ZHANG1,2()   

  1. 1.School of Resource & Environment and Safety Engineering, University of South China, Hengyang 421001, Hunan, China
    2.Hunan Engineering Technology Research Center of Mining Geotechnical Engineering Disaster Prediction and Control, Hengyang 421001, Hunan, China
  • Received:2021-07-14 Revised:2021-11-18 Online:2022-02-28 Published:2022-04-25
  • Contact: Zhijun ZHANG E-mail:1604309416@qq.com;zzj181@163.com

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Abstract:

With the improvement of mineral processing technology，the amount of tailings in storage is increasing year by year，and the particle size of tailings is getting finer and finer.However，such tailings have poor permeability，good water holding performance，long consolidation time and low mechanical strength.Such tailings often have problems such as difficult drainage，slow deposition and poor stability in the process of dam-filling.In the complex climate and geographical environment，rainfall infiltration，water evaporation，repeated rise and fall of saturation line （that is，under the condition of dry-wet cycle），earthquake and so on will be encountered.These factors can not be ignored for the settlement of fine tailings pond.In order to help calculate the settlement distance of tailings deposit and guide ore drawing and tailings dam construction，the influence of dry-wet cycle and moisture content on the compression consolidation characteristics of tailings of a metal tailings pond in Hunan Province was studied.The tailings with water content of 10%，12%，14%，16% and 18% were subjected to 0~5 times of dehumidification-moisture absorption-dehumidification tests respectively，and rapid consolidation tests were carried out on the samples with the help of GZQ-1 automatic high-pressure consolidation instrument.The results show that：（1）Under the same conditions，the void ratio decreases with the increase of pressure.Without the dry-wet cycle，the void ratio of the sample at the optimum moisture content is the smallest，and the void ratio of natural moisture content，optimum moisture content and saturated moisture content changes in a U-shaped curve in turn.After the dry-wet cycle，the volume of tailings sample expands slightly，and the internal water-gas channel changes.After graded loading，the internal particles fill the pores，and finally the structure tends to be stable.（2）Under the same number of cycles，the compression coefficient increases with the increase of water content， Under the same moisture content，the compression coefficient changes in a “Λ” shape with the increase of the number of dry-wet cycles.The number of dry-wet cycles and moisture content can increase the compactness of tailings and reduce the compression coefficient by changing the bonding effect and capillary water pressure of tailings cement.（3）Without drying-wetting cycle，the con-solidation coefficient first rises and then decreases with the increase of water content. At the same moisture content，the change of consolidation coefficient is approximately M-shaped with the increase of the number of dry-wet cycles.The stress in the early cycle process is mainly dominated by capillary water pressure.When the particles move stably and the pore structure of tailings is fully developed，the stress is dominated by cohesive force and friction force.Through the above three points，we can understand the stress characteristics of tailings sand consolidation process，assist in calculating the settlement distance of tailings accumulation，and guide ore drawing and sub-dam construction.Monitoring the environmental temperature and precipitation，controlling the water content of tailings and the accumulation period of tailings can improve the economic benefit and stability of tailings dam.

Key words: dry-wet cycle, moisture content, tailings sand, e-p curve, compression coefficient, coefficient of consolidation

CLC Number: 

  • TD926.4

Fig.1

Particle size distribution curve of tailings"

Table 1

Tailings grading parameters"

参数数值
有效粒径d10/mm0.152
中值粒径d30/mm0.181
限制粒径d60/mm0.208
不均匀系数Cu1.370
曲率系数Cc1.040

Fig.2

Dry density curve"

Table 2

Basic physical property parameters of tailings"

参数数值
自然干密度ρd/（g·cm-3）1.734
最优含水率ω/%16%
自然含水率ωop/%9%
比重Gs2.66
孔隙比e0.517

Fig.3

Schematic of sample and mold"

Fig.4

Sectional view of test equipment"

Fig.5

GZQ-1 automatic high pressure consolidation instrument"

Fig.6

Schematic diagram of dry-wet cycle process"

Fig.7

The e-p curves under different moisture content"

Fig.8

The e-p curves under different cycle times"

Fig.9

Particle change diagram of sample during test"

Fig.10

Compression coefficient diagram under different moisture content"

Table 3

Compressibility of soil compressibility coefficient at 100~200 kPa"

压缩系数/（MPa-1）土体压缩性
<0.1低压缩土
0.1~0.5中压缩土
>0.5高压缩土

Fig.11

Consolidation coefficient diagram under different moisture content without dry-wet cycle"

Fig.12

Consolidation coefficient diagram under different cycle times"

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