调浆强化细粒煤泥浮选作用机理
Mechanism of conditioning on improving fine coal flotation
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摘要: 浮选是细粒煤泥分选的有效方法，调浆作为浮选前的预处理环节，对浮选效果具有重要的 影响。 以某地区露天开采的细粒含量较高的难浮煤泥为研究对象，研究了煤油用量和搅拌转速对 精煤可燃体回收率、精煤灰分和浮选动力学的影响，通过膜浮选对不同搅拌转速下调浆后煤泥表面 疏水性的变化进行研究，利用聚焦光束反射仪( FBRM) 对调浆过程中煤油液滴和煤泥颗粒粒径随 搅拌转速和搅拌时间的变化进行在线实时分析，通过红外光谱分析仪( FTIR) 对不同搅拌转速下调 浆前后煤表面的煤油吸附量进行研究，对不同搅拌转速调浆后颗粒的絮体进行了图像分析，对调浆 过程中煤油分散后和分散前与煤粒的碰撞概率比进行了理论计算。 试验结果表明，在搅拌转速为 900 ~ 1 800 r / min 时，随着搅拌转速的增加，精煤累计可燃体回收率和浮选速率常数逐渐增加，精煤 灰分呈下降的趋势。 膜浮选结果表明，调浆搅拌转速的增加提高了颗粒表面的疏水性。 在 900 r / min的低搅拌转速下，煤油分散效果较差，且延长搅拌时间对煤油分散效果的提高作用不明 显，随着搅拌速度的增加，分散后煤油液滴的数量显著增加，且在较短的时间内能达到较好的分散 效果。 FBRM 和絮团图像分析结果表明，调浆后细颗粒发生了较明显的剪切絮凝，且在一定程度上 随着搅拌转速的增加絮凝作用增强。 搅拌转速从 900 r / min 增加到 1 800 r / min 时，调浆后矿浆中 -50 μm颗粒数量逐渐减少，尤其是-20 μm 颗粒数量显著减少，同时+300 μm 粒级数量增加。 煤表 面煤油吸附量随着搅拌转速的增加逐渐增加。 理论计算表明，当煤泥粒度一定时，煤油分散后与分 散前的粒度比越小，煤油分散程度越高，与煤粒碰撞概率比越大。 在调浆过程中，煤油分散程度提 高显著增加了煤油液滴与煤颗粒的碰撞概率。Abstract: Flotation is an effective method for the separation of fine coal slime.Conditioning has a significant effect on the flotation performance when used as a pre⁃treatment process before flotation.The effects of kerosene dosage and stirring speed on combustible recovery，ash and flotation kinetics were studied by using a difficult⁃to⁃float coal sample with high fine particle content from a surface mining.The changes in the hydrophobicity of the particle surface un⁃ der different stirring speeds were analyzed by film flotation.The distributions of kerosene droplets and coal particles un⁃ der different stirring speeds and stirring time in the conditioning process were measured in real time by using the focused beam reflectance measurement(FBRM).The kerosene adsorption on the coal surface under different stirring speeds were studied by the infrared spectrum analyzer(FTIR).The effects of different stirring speeds on particle flocs were observed by microscopy，and the collision probability between oil droplets and coal particles was calculated theo⁃ retically.The results showed that the combustible recovery and flotation rate constant increased gradually while the ash decreased with the increase of stirring speed from 900 to 1 800 r/min. The results of film flotation indicated that the hydrophobicity of particle surface was improved with the increase of stirring speed.The dispersion ef⁃ ficiency of kerosene was relatively low at a stirring speed of 900 r / min.However，the dispersion efficiency of kerosene was improved significantly with the increase of stirring speed，and the dispersion could be achieved in a relatively short time.The flocs of fine particles were formed through shear flocculation after conditioning verified by FBRM and floc image analysis.When stirring speed increased from 900 to 1 800 r / min，the number of -50 μm coal particles de⁃ creased gradually，especially for the -20 μm particles.The kerosene adsorption on coal surface increased gradually with the increase of stirring speeds.Theoretical calculation revealed the collision probability between kerosene droplets and coal particles increased with the increase of kerosene dispersion when the coal particle size was constant.
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