微纳米气泡与矿物颗粒的多相界面作用研究

STUDY OF MULTI-INTERFACE INTERACTIONS BETWEEN COAL PARTICLES AND MICRO-NANOBUBBLES

刘力铭

11849344

硕士

化学工程领域工程

翁力

2020-05-28

2020-07-20

哈尔滨工业大学

深圳

浮选是工业上常用的低质煤提质改性工艺，主要是根据煤中可燃体与矿物质表面性质差异实现不同矿物有效分离的过程。然而，对于细粒煤，煤颗粒与浮选气泡间碰撞概率低是限制其高效浮选回收的决定性因素之一。针对这一问题，论文以不同疏水性细粒太西煤为研究对象，提出通过引入微纳米气泡（MNBs）强化细粒煤浮选过程的思路，在揭示不同条件下MNBs基本性质的基础上，深入研究MNBs与煤颗粒间相互作用行为，并初探基于MNBs强化的细粒煤颗粒聚团-浮选行为。论文首先实现了MNBs的制备与表征。通过溶氧测试和动态光散射（DLS）分析，初步揭示了不同水样溶氧量差异，探明不同条件下MNBs尺寸分布及表面电位的性质。研究结果表明，由气泡发生器制备的MNBs增加了水中溶氧量，其平均尺寸为200 ~ 700 nm。MNBs表面有很强的负电性，同时静置1 h后仍能检测到MNBs，与常规气泡相比稳定性较好。同时，仲辛醇浓度、静置时间、气泡发生器循环处理时间、外加充气量和pH都是影响MNBs基本性质的重要因素。通过FT-IR、接触角测试、DLS的研究手段，论文揭示了MNBs与细粒太西煤间相互作用行为。研究结果表明，太西煤的疏水性随着氧化温度的升高而降低。引入MNBs后，MNBs易在疏水煤表面附着，提高疏水煤的疏水性，但对亲水煤表面疏水性的影响不大；MNBs在煤表面吸附能够降低煤颗粒表面电位，且煤表面疏水性越强电位降低越显著。通过激光粒度仪、显微镜观察、流变仪测试，论文进一步研究了MNBs对细粒太西煤聚团-浮选行为的影响，并初探细粒金达煤泥-MNBs浮选工艺。研究结果表明，MNBs能提高疏水煤的浮选速率和回收率，但对亲水煤影响不大，主要原因是MNBs促进了疏水煤的聚集，但对亲水煤几乎无影响。浮选动力学拟合结果表明，经典一阶动力学模型对太西煤浮选试验拟合效果最佳。细粒金达煤泥-MNBs浮选工艺表明MNBs的引入提高了浮选效果，浮选3 min得到精煤产率为35.2%，灰分含量从52.35%降到15.6%的良好指标。

Froth flotation is an effective method for separating fine target minerals from gangue minerals, depending on their surface hydrophobicity differences. However, the low probability of collision between coal particles and flotation bubbles severely limits the high-efficiency flotation of fine and ultra-fine coal particles. To address this issue, in this study, we proposed the idea of strengthening the flotation of fine and ultra-fine coal particles by introducing micro-nanobubbles (MNBs). Based on revealing the basic properties of MNBs under different conditions, the interaction between MNBs and coal particles was further studied, and the process of MNBs enhanced agglomeration-flotation technique of ultra-fine coal particles was preliminarily explored.Through dissolved oxygen test and dynamic light scattering (DLS) analysis, the preparation method and fundamental properties of MNBs generated were ascertained initially. The results showed that the average size of MNBs prepared by the bubble generator was from 200 nm to 700 nm. Meanwhile, MNBs are negatively charged, which is probably one of the main contributors to the long life-time of MNBs. It was also found that the concentration of 2-octanol, the setting time, the cycle time of the bubble generator, the additional aeration and pH were all critical factors affecting the basic properties of MNBs.Afterward, the interaction between MNBs and ultra-fine TX coal was revealed by FT-IR, contact angle test and DLS analysis. The results showed that the hydrophobicity of TX coal decreased as the increase in oxidation temperature. On the other hand, MNBs adhered to the hydrophobic coal particles easily so to increase their surface hydrophobicity while had little effect on the hydrophobicity of hydrophilic coals. Compared with hydrophilic coal particles, higher coal particle’s surface hydrophobicity triggered more MNBs, inducing a more significant reduction of coal particle Zeta potential.Through laser particle size analyzer, microscope observation, and rheometer test, the effect of MNBs on the agglomeration-flotation of ultra-fine TX coal was further studied, with a preliminary study on the ultra-fine JD coal-MNBs flotation test was carried out to propose a new process. The results showed that MNBs increased the flotation rate and combustible recovery of hydrophobic coal but had little effect on hydrophilic coal. The main reason was probably that MNBs promoted the aggregation of hydrophobic coal while the fitting results of flotation kinetics showed that the classical first-order kinetics model had the best fitting effect on the TX coal flotation test. The new process of ultra-fine JD coal-MNBs flotation showed that the introduction of MNBs improved the flotation efficiency, and the combustible recovery is up to 35.2%, and the ash content was reduced from 52.35% to 15.6%.

微纳米气泡 细粒煤颗粒 聚团 浮选 浮选动力学

micro-nanobubbles fine and ultra-fine coal aggregation flotation kinetics

中文

联合培养

南方科技大学

刘力铭. 微纳米气泡与矿物颗粒的多相界面作用研究[D]. 深圳. 哈尔滨工业大学,2020.