【作者】 苗真勇；

【导师】 刘炯天；

【作者基本信息】 中国矿业大学 ， 化学工艺， 2013， 博士

【摘要】 随着原煤入洗比例的增大，煤泥产量逐年增加，以煤泥为原料制备煤泥浆是大规模综合利用煤泥的理想途径。本论文针对低阶高灰煤泥的表面物理化学特征和矿物特性，设计并合成与之相匹配的水煤浆分散剂，重点从胶体化学和溶液化学角度研究煤泥中矿物质对其成浆作用的影响规律，考察分散剂与煤泥的吸附机理及动力学，从溶液环境、煤质因素和分散机理等方面对煤泥浆分散特性进行调控，开发了浓度高、稳定性好的低阶高灰煤泥水煤浆。低阶煤泥具有的丰富侧链、含氧官能团和发达的孔隙等特点，大量水分被吸附在其表面，造成水不能参与自由流动和润滑作用。此外，矿物质含量高也会对浆体分散产生一定影响。针对低阶高灰煤泥的成浆特性，结合量子化学计算模拟，对煤泥制浆用分散剂进行了分子结构设计，筛选并成功合成了羧酸盐类阴离子型分散剂（SAF-A），研究了SAF-A分散剂对低阶煤泥的制浆效果。研究表明，SAF-A分散剂中引入脂肪族大分子长链和羧酸基团，可与低阶煤中的侧链、含氧官能团有效的结合，引入酰胺基团抑制矿物离子对浆体性能的不利影响。同时，SAF-A分散剂具有较长的支链，在体系中易于形成稳定的网格结构，既能够提供足够的空间位阻，也可以减缓煤粒的沉降速度，使浆体具有更好的稳定性。在用量为传统萘系（NSF）和木系（LS）分散剂60%条件下，制浆浓度可提高2.5%左右，并表现出良好的流动性和稳定性。利用胶体化学基础理论与方法研究了煤泥中矿物对其成浆作用的影响规律，并运用扩展的DLVO理论计算了煤颗粒间以及煤与矿物颗粒间的相互作用。研究表明，单位质量矿物颗粒对SAF-A分散剂的饱和吸附量远大于煤颗粒的饱和吸附量，矿物和煤颗粒在吸附分散剂后，电负性增强，水化膜厚度增加，浆体的稳定性和流动性提高。煤颗粒间以及煤与矿物颗粒的总作用能UT存在能垒和临界距离，当颗粒间距离大于临界距离时，主要存在静电斥力作用；当颗粒间距离小于临界距离时，界面极性作用占主导作用。与煤和矿物颗粒间相比，煤颗粒间UT的临界距离最大且能垒最低；在相同距离时，矿物颗粒的存在能够使UT趋于正值，有利于抑制颗粒凝聚，提高浆体的分散稳定性。研究了体系中高价金属阳离子对煤颗粒吸附分散剂的影响规律，考察了矿物离子对煤表面电性、双电层厚度的影响及对分散剂的配位作用。结果表明，高价金属阳离子的存在会消耗分散体系中的分散剂，SAF-A分散剂可抑制此类消耗，表现出较强的抗矿物离子能力。高价金属阳离子易与SAF-A分散剂发生配位效应，形成稳定的配位络合物，减弱SAF-A分散剂的分散效果；矿物离子可压缩煤颗粒表面双电层结构，削弱静电斥力作用，使煤颗粒容易凝聚，增加浆体的粘度。与单独作用相比，高价金属阳离子的共同作用对SAF-A分散剂的吸附量及颗粒双电层厚度影响均不明显，而对矿物离子与分散剂的配位效应影响显著，更容易形成稳定的配位络合物。研究了SAF-A分散剂在煤泥浆分散体系固/液界面的吸附机理及动力学，确定了SAF-A分散剂在煤泥表面的吸附类别、吸附作用力类型和吸附形态。研究表明SAF-A分散剂在煤泥表面的吸附等温线呈L型，SAF-A分子以平躺状态单层吸附在煤粒表面，该吸附行为既符合Langmuir又符合Freundlich方程，且为放热的自发吸附过程。SAF-A在煤泥表面的吸附存在静电吸附作用、疏水吸附作用和氢键吸附作用。SAF-A在煤泥表面的饱和吸附浓度为0.8g·L^-1，饱和吸附浓度下，动力学方程拟合表明，不同温度、pH值、离子强度下吸附过程符合二级动力学方程，表面活化能Ea=8.50kJ·mol^-1。温度升高，吸附速率增加，pH值和离子强度增加，吸附速率降低。考察了SAF-A分散剂、溶液环境、煤质改性条件等因素对煤泥制浆的影响规律，建立了适用于低阶高灰煤泥制浆的分散调控机制和浆体性能预测模型。结果表明，随SAF-A/LS复配比例降低，浆体成浆浓度呈先增加后降低趋势，复配比例为7:3时，浆体成浆性能最佳。成浆温度升高改变SAF-A分散剂与煤泥颗粒间氢键作用，浆体成浆性能先增加后降低；煤泥表面电负性随溶液pH值升高而降低，颗粒间静电斥力增大，有利于高性能煤泥水煤浆的制备。煤泥浮选降灰可提高煤泥浆中可燃体浓度，降低矿物离子浓度，增加SAF-A分散剂有效作用量，浆体稳定性升高；小于400℃的低温短时改性可有效降低氧含量和内水含量，使煤泥成浆浓度显著提高。煤泥中的表面含氧官能团、内水含量和矿物质是影响煤泥制浆的关键因素，建立了基于煤质因子的煤泥成浆浓度BP神经网络预测模型。更多还原

【Abstract】 The thesis aims at designing and synthesizing dispersan for slime of low-rank,high ash, and fine granularity. From the view of solution and interface chemistry, theeffect and mechanisms of the minerals on the slurry properties were studied.Adsorption kinetics and thermodynamics characteristics of dispersant and slime areinvestigated, and the surface adsorption mechanism of action of prepared dispersantson slime is analysed. According to the factors of dispersant, solution environment,coal to regulate coal slurry dispersed system, and to improve the performance of thecoal slime water slurry(CSWS).According to quantum chemical computational simulation, CSWS dispersant ismolecular structure designed, anionic dispersing agent of the carboxylic acid salts(SAF-A) is screened and consequently synthesized. The effect of SAF-Adispersant onlow-rank coal is studied. The results showed that SAF-A dispersant can effectivelycombined with low-rank coal and the adverse effects of mineral ions to the slurry caneffectively inhibited. The pulping concentration can increase by2.5%and exhibitgood fluidity and stability under the condition that the weight of the dispersant in thereaction all accounting60%of the weight of traditional naphthalene-based(NLS) andwood-based(LS) dispersant.Based on theories and methods of colloid and solution chemistry, the principalsof insoluble minerals and mineral ion pulp on CSWS are researched. The resultsshowed that when the insoluble minerals and slime adsorbed the dispersant, theelectronegativity will be greatly enhanced. The thickness of hydration film willincreased and the slurry were more stabile and liquidity. With DLVO theory adopted,the electrostatic interaction of coal particles and the electrostatic interaction of coalwith calcite, quartz increases with grain spacing, the coal particles and the interfacebetween the coal and various minerals are attractive polarity role; in the same distance,the minerals in coal can improve the total interaction between the particles in thedispersion system, appearing mutual repulsion, helping to restrain particle aggregationand can improve stability of the slurry. The presence of a mineral ion is able toconsume the dispersant in the dispersion system. Under the condition of the samemineral ions concentration, the consumption of SAF-A dispersant by the mineral ionsin dispersion system reduced about10%of the original quantity comparing with theconsumption of lignin sulfonate, with showing the strong anti-mineral ion capacity. Mineral ions are easy to occur complex effects with SAF-A dispersant, weakening theeffect of the SAF-A; they can also compress coal particles in the surface electric doublelayer structure, agglomerating the coal particles easily, increasing the viscosity of theslurry. The mineral ion interactions has a little effect on the consumption of thedispersant and the thickness of the electrical double layer of the coal particles while agreat influence on the coordination between mineral ions and dispersant.The SAF-A dispersant in the solid/liquid interface of the coal slurry were studiedon the adsorption kinetic, adsorption thermodynamics and determined category, actingforce and form of adsorption. The studies found that adsorption was in line withsecond-order equation in different temperature, pH and ionic strength, the adsorptionrate is increased with temperature, while the pH value and ionic strength increases, theadsorption rate decreases. The adsorption behavior is in line with the Langmuir andthe Freundlich equation and is also the spontaneous exothermic process. There areelectrostatic, hydrophobic and hydrogen adsorption in this process.SAF-A dispersant, solution environment, coal quality modification conditionswere studied to establish the suitable prediction model for low-rank high ash slimepulp and pulping performance. The results showed that, with the complex ratio ofSAF-A/LS decreasing, slurry concentration was first increased and then decreased.The slurry performance was best at the complex ratio of7:3. The hydrogen bondinginteraction between SAF-A and coal particles was changed with slurry temperature.The slurry performance first increased and then decreased when the slurrytemperature increased. The slime surface electronegativity decreased with solution pHvalue increased and the electrostatic repulsion between particles increased conducingto the preparation of high performance slime CSWS. Oxygen-containing functionalgroups, internal water content and minerals onthe surface of slime are the key factorsto affect the slime pulp. Temperature less than400℃can effectively reduce theoxygen content and the inner water content in a short time, significantly increasingslurry concentration. Coal slime flotation dropping ash can enhance the combustibleconcentration in the coal slurry, reduce mineral ions concentration, increase theeffective action of SAF-Adispersant and improve the stability of the slurry.更多还原