细粒脉石在疏水性煤炭颗粒表面上的罩盖(细泥罩盖)是细泥污染浮选精煤的方式之一，同时也是造成煤炭可浮性变差、精煤回收率降低的重要原因。通过单气泡负载试验研究了3种不同的脉石矿物(石英、高岭石、伊利石)在煤炭表面的细泥罩盖程度以及对煤炭可浮性的影响规律。结果表明，随着煤炭与脉石混合搅拌时间的延长，3种脉石与煤炭之间的细泥罩盖程度逐渐增加，并且整个过程均呈现先快后慢的趋势，在40 min左右细泥罩盖程度基本不再变化。在流场剪切速率相同的情况下，石英的细泥罩盖程度最弱，高岭石次之，伊利石的细泥罩盖程度最强，这与超冷冻扫描电镜的观测结果以及煤炭与脉石颗粒间DLVO作用力计算结果是一致的。随着流体剪切速率的升高，3种脉石与煤炭之间的细泥罩盖程度均有所降低，煤炭的可浮性得到增强，其中石英的细泥罩盖在剪切速率为58 s^-1时基本完全消除，但是高岭石和伊利石的细泥罩盖在剪切速率达到116 s^-1时仍然存在。之后对煤炭-脉石混合矿物进行了在不同剪切速率下调浆后的浮选试验，结果表明在浮选前进行高速剪切调浆能够减少石英、高岭石和伊利石在煤炭表面的细泥罩盖，并提高煤炭的浮选回收率。但高速剪切调浆使脉石的分散性提高，造成浮选时脉石的水流夹带加剧，需要结合其他方法抑制脉石对浮选精煤的污染。

The slime coating of gangue on the surface of hydrophobic coal particles is one of gangue contaminations to the flotation clean coal,and it is also a main reason for the deterioration of coal floatability and the decrease of clean coal recovery.The degree of slime coating and its influence law of three kinds of gangue minerals(quartz,kaolinite and illite) on the coal floatability were studied by a single bubble loading test in this study.The results showed that with the increase of the stirring time of coal and gangue mixture,the degree of slime coating between the gangue and coal particles increased with time and almost did not change after 40 minutes.The slime coating was fast at first and then slowed down.Under the condition that the fluid shear rate kept constant,the degree of slime coating of quartz was the weakest,kaolinite the second,and illite the strongest,which was consistent with the observation of cryogenic scanning electron microscope (Cryo-SEM) and the inter-particle force calculation based on the DLVO theory.With the increase of fluid shear rate,the degree of slime coating between the gangue and coal particles was inhibited and the floatability of coal was improved.The slime coating of quartz was almost eliminated at the shear rate of 58 s^-1,but the slime coating of kaolinite and illite still existed at the shear rate of 116 s^-1.The flotation experiments of coal-gangue mixture were carried out after the agitation with different shear rates.It was found that the high intensity agitation before flotation could mitigate the slime coating of quartz,kaolinite and illite on coal surface,and improve the flotation recovery of coal.But the high intensity agitation increased the dispersion of gangue,which resulted in the aggravation of water entrainment of gangue during flotation.It is necessary to combine other methods to restrain the contamination of gangue to the flotation clean coal.

1 试验材料与方法

   1.1 试验材料

   1.2 单气泡负载试验

   1.3 冷冻扫描电镜试验

   1.4 zeta电位测试

   1.5 浮选试验

   1.6 矿浆黏度测量

2 试验结果与讨论

   2.1 脉石种类对煤炭可浮性的影响

   2.2 流体剪切速率对煤炭可浮性的影响

   2.3 高速剪切调浆对煤炭浮选的影响

3 结论