褐煤改性对其表面特性及成浆性的影响

Effect of lignite modification on its surface properties and pulping properties

针对蒙东胜利褐煤孔隙率高、表面含氧官能团丰富、储运困难、成浆性差等问题,以阴离子石蜡乳液对褐煤表面进行改性,对褐煤改性前后表面性质的变化和成浆性进行研究。采用热重分析仪(TG)研究了空干基褐煤(ADL)和改性空干基褐煤(BADL)的热失重规律;采用X射线光电子能谱(XPS)、氮气吸附比表面积测试法(BET)对热风干燥后的褐煤(DL)和改性后的干燥基褐煤(BDL)表面官能团、比表面积和孔结构进行研究;通过成浆性试验研究改性前后褐煤成浆性的变化。结果表明,ADL通过阴离子石蜡包覆改性后,50~150℃时,BADL质量变化速率绝对值小于ADL,117.82℃时,绝对值相差最大,为0.34%/min;DL通过阴离子石蜡包覆改性后,表面无机氧含量从0.64%降低至0.20%,C=O和COO-含量分别从13.93%和12.22%降至13.11%和12.03%;比表面积从8.790 m 2/g变为14.995 m 2/g;孔体积从0.041 cm 3/g降低至0.032 cm 3/g,平均孔径从32.697 nm降低至17.054 nm;以水煤浆表观黏度小于1300 mPa·s、流动性好于B-(12 cm)为评价标准,褐煤改性后结合使用分形级配制浆工艺,最高成浆浓度可达60.59%,与未改性前相比,最高成浆浓度提升了10个百分点,表观黏度从1059 mPa·s降至682 mPa·s,提高了水煤浆的稳定性。

The East Mongolia Shengli lignite,with the properties of high porosity,abundant oxygen functional groups on the surface,difficult storage and transportation and poor slurry properties,was modified with the anionic paraffin emulsion,and the change of the surface properties and the pulp properties of the modified lignite were studied.The thermo-gravimetric characteristics of the air dried lignite(ADL)and the modified air dried basis(BADL)of lignite was studied by thermo gravimetric analysis(TG).The change of surface functional groups,specific surface area and pore structure of dry basis lignite dried by hot wind and modified dry basis lignite were studied by X-ray photoelectron spectroscopy and nitrogen adsorption specific surface area test.The pulping property of lignite before and after modification was studied by slurry forming test.The results show that after the ADL modified by the anionic paraffin emulsion,the absolute mass change rate of BADL is less than that of ADL at the temperature range from 50 to 150 degrees centigrade.When the temperature is 117.82 degrees,the absolute value difference is the maximum 0.34%/min.When the DL is modified by anionic paraffin milk,the content of the surface inorganic oxygen is reduced from 0.64%to 0.20%,and the content of C=O and COO—decrease from 13.93%and 12.22%to 13.11%and 12.03%,respectively.The specific surface area changes from 8.790 m 2/g to 14.995 m 2/g;the pore volume decreases from 0.041 cm 3/g to 0.032 cm 3/g,and the average pore size decreases from 32.697 nm to 17.054 nm.The coal water slurry viscosity is less than 1300 mPa·s,and the liquidity is better than B-(12 cm)as the standard,the modified lignite is pulped with fractal gradation process,and the maximum pulp concentration can reach 60.59%.Compared with the single stick grinding process before the unmodified coal,the maximum slurry concentration increases by 10 percentage points,The apparent viscosity decreases from 1059 to 682 mPa·s,which improves the stability of coal slurry.