超声波作用下尾砂浆浓密沉降及放砂

Thickening sedimentation and sand discharge of tailings slurry under ultrasonic

为了提高砂仓中尾砂浓密效率,实现高浓度的放砂,引入声场作为研究手段,创新性的利用声场辐射方式传播的特性,将声场非接触性地作用于尾砂浆介质中.通过设计试验,配制质量分数为40%的尾砂砂浆,在尾砂浆分别沉降15,20,25,30,35和40 min后,施加频率20 k Hz,功率50 W的超声波,探究不同沉降时间后施加超声波作用对最终沉降时间和浓度的影响,同时将超声波作用在砂仓放砂阶段,并对超声波作用后不同浓度的砂浆进行流变参数测定.试验结果表明:在沉降20 min后施加超声波,砂浆沉降浓密时间最短为80 min,尾砂浆最终质量分数可达77.5%,与此同时超声波作用下可以实现砂仓稳定高浓度的放砂,放出砂浆质量分数为74.04%.对比超声波处理前后砂浆黏度与屈服应力可知,超声波可有效降低砂浆黏度22.3%,具有良好的降黏效果.超声波的振动作用,空化作用以及声流效应是使得砂浆快速浓密沉降以及放出的原因.

To improve the thickening efficiency of tailings in sand bins and achieve a high-concentration sand discharge,the sound field as a research method was introduced,and the characteristics of sound-field radiation to transmit the non-contact sound field was innovatively used to tailings slurry. Tailings slurry with 40% in mass fraction was prepared for the experiment. After 15,20,25,30,35,and 40 min of sedimentation,an ultrasonic wave of 20 k Hz and 50 W of power were applied to investigate the effect of ultrasonic waves on the final settling time and concentration with different settling times. Ultrasonic wave was also applied to the sand discharge stage,and the rheological parameters of the tailings slurry at different concentrations were measured. The results show that when an ultrasonic wave is applied after 20 min of sedimentation,the shortest slurry sedimentation time of 80 min can be obtained and the final sediment mass fraction of the tailings slurry can reach 77. 5%. Therefore,under ultrasonic action,it is possible to achieve stable sand discharge with a high-concentration tailings slurry at the same time,and the discharge mass fraction up to 74. 04%.Comparisons of the viscosity and yield stress of the tailings slurry before and after ultrasonic treatment indicate that the viscosity of the slurry can be effectively reduced by 22. 3% by ultrasonic action,which is a good viscosity reduction effect. Ultrasonic vibration,cavitation,and the acoustic streaming effect are the reasons for the rapidly thickening sedimentation and discharge of the tailings slurry.