基于低场核磁共振表征的矿物孔隙润湿规律

孔隙润湿是影响多孔矿物(焦渣、褐煤、冶金渣等)可浮性的重要因素之一,然而准确、定量表征孔隙润湿的方法鲜有研究,润湿液体性质与孔隙润湿规律之间的内在联系还未被充分地揭示。采用原样和疏水活性炭开展基于液体物理性质的孔隙润湿规律研究,建立低场核磁共振(¹H LF-NMR)测得¹H LF-NMR孔隙率与称重法计算得到的称重孔隙率之间的定量关系,探讨¹H LF-NMR检测样品在4种液体中润湿不同时间后的孔隙润湿率的可行性;研究4种液体对样品中不同尺寸孔隙的润湿规律;通过计算收缩数,揭示液体物理性质在样品孔隙润湿过程中的影响机理。结果表明:原样和疏水样品在4种液体中润湿后,¹H LF-NMR孔隙率与称重孔隙率具有一次函数关系,故该设备可定量表征出4种液体对原样和疏水样品中孔隙的润湿率。4种液体润湿原样和疏水性样品时不同尺寸孔隙均符合“快增—稳定”的规律,润湿速率由快到慢的转折点在5 min处,总孔的润湿率与润湿时间均符合一级动力学方程,纯水对原样具有最大的总孔润湿速率但对疏水样品的总孔润湿速率却最小。对于原样,纯水具有最大微孔和过渡孔润湿率,正丙醇和正十六烷具有最大中孔润湿率且对疏水样品中孔润湿率相似,而硅油对所有孔隙润湿率都最小;60 min孔隙润湿率(除中孔)随收缩数增加而线性降低,表明液体黏度主导孔隙润湿过程。按照疏水样品微孔和过渡孔润湿率递减排序依次为正丙醇、正十六烷、纯水、硅油;60 min孔隙润湿率随收缩数增加先升高后降低,反映出表面张力和黏度对孔隙润湿过程的协同作用。

Pore wetting law of minerals by1H LF-NMR characterization

Pore wetting is one of the important factors affecting the floatability of porous minerals,i.e.cinder,lignite,metallurgical slag,etc.However,there are few studies on the accurate and quantitative characterization method of pore wetting.The essential relationship between the properties of wetting liquids and the pore wetting law has not been revealed yet.Therefore,in this investigation,the raw and hydrophobic active carbons are used to study the pore wetting law based on the physical properties of liquids.The quantitative relationship between 1H LF-NMR porosity detected by 1H LF-NMR and weighting porosity by weighting method is established.The feasibility of 1H LF-NMR detection on the pore wetting of raw and hydrophobic samples in four liquids for different times is explored.The wetting law of pores of different sizes in raw and hydrophobic samples wetted by four liquids is discussed.The Crispation number is calculated to reveal the mechanism of physical properties of liquids affecting the pore wetting process of raw and hydrophobic samples.The result shows that the 1H LF-NMR porosity has a linear function correlation with the weighting porosity after the raw and hydrophobic samples are wetted by four liquids.Thus,this device can quantitatively characterize the pore wetting percentage of raw and hydrophobic samples.The pores of different sizes conform to the“fast-unchanged”wetting law when the raw and hydrophobic samples are wetted by four liquids.The turning point of the wetting rate from fast to slow occurs at 5 min.The relationship between the wetting percentage of the total pores and the wetting time is a first-order kinetic equation.Pure water has the largest total pore wetting percentage for the raw sample but the smallest for hydrophobic sample.For raw sample,pure water achieves the largest wetting percentages of micro-pores and transition pores.The n-propanol and n-hexadecane have the largest wetting percentage of meso-pores,which are similar to hydrophobic sample.However,silicone oil has the lowest wetting percentage for pores of all sizes.The 60-min wetting percentages of pores in raw sample(except meso-pores)decrease linearly with the increase of Crispation number,indicating that liquid viscosity dominates the pore wetting process.The wetting percentages of micro-pores and transition pores in the hydrophobic sample from large to small are n-propanol,n-hexadecane,pure water and silicone oil.The 60-min pore wetting percentages in the hydrophobic sample(except meso-pores)increase first and then decrease as the Crispation number increases.The synergistic effects of surface tension and viscosity on the pore wetting process are reflected.