煤气化细渣是煤气化过程中产生的富含残炭和多种无机组分的固体废弃物，其目前主流的处理方法为堆存和填埋，这不仅对生态环境和人类健康构成威胁，同时也造成了资源的浪费。煤气化细渣的炭灰组分分离是其资源化利用和无害化处置的前提，因其含水量高且粒度细，目前常用的炭灰组分分离方法为浮选法。然而，因炭灰组分黏连、捕收剂不易分散等，使得煤气化细渣浮选存在捕收剂用量大、残炭回收率低等问题。超声预处理在改善物料的物化性质及药剂的粒径分布方面具有显著优势，有望提高煤气化细渣的浮选分离效率。本文以陕西煤业化工集团公司某典型水煤浆气化工艺副产物的煤气化细渣为研究对象，分别研究了煤气化细渣样品的超声预处理、捕收剂的超声预处理、样品与捕收剂的同步/分步超声预处理对煤气化细渣浮选效果的影响，并探讨了各超声预处理方式强化气化细渣浮选的作用机理。

首先，探究了灰渣样品的超声预处理对煤气化细渣浮选的影响。最佳超声预处理时间和功率分别为9 min和540 W；最佳浮选参数为矿浆浓度60 g/L、搅拌转速1800 r/min及充气量0.18 m³/h。与未超声预处理时相比，样品经超声预处理后精矿产率增加了8.39%，可燃体回收率提高了13.40%，灰分降低了4.72%。通过粒度组成、FTIR、XPS、SEM、BET等分析超声预处理前后物化性质变化，阐明超声波在煤气化细渣浮选中的作用机制。粒度组成分析发现样品经超声预处理后粗颗粒减少，细颗粒增多且灰分降低，表明煤气化细渣在一定程度上实现破碎解离；SEM、BET分析发现样品经超声预处理后残炭颗粒孔隙结构完整、表面光滑、黏附于残炭表面或孔隙内的高灰杂质减少，使其残炭颗粒暴露出新鲜表面；XPS分析发现，经超声预处理后残碳表面的极性含氧官能团含量减少，从而增强残炭表面的疏水性及其可浮性；经超声预处理后矿浆中水分子解离产生的^.OH自由基得电子生成OH  ^-，导致矿浆pH值增大，弱碱环境有利于煤气化细渣炭灰分离。

其次，探究了捕收剂的超声预处理对煤气化细渣浮选的影响。超声乳化捕收剂中水:柴油:Span80:Tween80最佳质量比为60:24:14.4:1.6；最佳超声预处理功率和时间分别为540 W和6 min。与未超声预处理时相比，捕收剂经超声预处理后精矿产率增加了19.98%，可燃体回收率增加了27.15%，灰分降低了3.24%。FTIR分析发现捕收剂与煤气化细渣作用前后对比，未出现新的吸收峰，表明捕收剂在煤气化细渣表面的吸附为物理吸附。激光粒度分析表明，超声预处理后乳化捕收剂在水中粒径及分散性显著优于柴油；诱导时间及浮选动力学分析表明，超声乳化捕收剂可缩短残炭颗粒与气泡之间的粘附矿化时间，使其可浮性更好。

最后，探究了灰渣样品与捕收剂的同步/分步超声预处理对煤气化细渣浮选效果的影响。同步超声预处理功率和时间分别为540 W和9 min时效果最佳，与常规浮选相比精矿产率增加了3.06%，可燃体回收率增加了6.00%，灰分降低了4.70%；分步超声预处理功率和时间分别为540 W和11 min时效果最佳，与常规浮选相比精矿产率增加了10.14%，可燃体回收率增加了16.87%，灰分降低了6.88%。同步超声预处理时的浮选可燃体回收率低分步超声预处理，这是由于同步超声虽然增加了颗粒与药剂的碰撞概率，但是超声预处理时间过长会使其结构稳定性变差；分步超声预处理时矿浆与药剂性能均达到了最佳，乳化捕收剂能够更好的吸附于暴露出的新鲜解离面。

Coal gasification fine slag is a solid waste rich in carbon residues and inorganic components produced in the process of coal gasification. At present, the main treatment methods are stacking and landfilling, which not only poses a threat to the ecological environment and human health, but also causes a waste of resources. The separation of carbon ash components from coal gasification fine slag is the premise of its resource utilization and harmless disposal. Flotation method is commonly used for the separation of carbon ash components because of its high water content and fine particle size. However, due to the adhesion of the carbon ash components and the difficulty of dispersing the collector, there are many problems such as large amount of collector and low recovery rate of carbon residue in coal gasification fine slag flotation. Ultrasonic pretreatment has significant advantages in improving the physicochemical properties of materials and the particle size distribution of chemicals, and is expected to improve the flotation separation efficiency of coal gasification fine slag. In this paper, the effects of ultrasonic pretreatment of coal gasification fine slag samples, ultrasonic pretreatment of collector, and synchronous/stepby-step ultrasonic pretreatment of sample and collector on the flotation effect of coal gasification fine slag were studied in Shaanxi Coal Industry Chemical Group Company. The mechanism of each ultrasonic pretreatment method to enhance the flotation of gasification fine slag was also discussed.

Firstly, the effect of ultrasonic pretreatment of ash and slag samples on the flotation of coal gasification fine slag was investigated. The optimal pretreatment time and power were 9 min and 540 W, respectively. The optimum flotation parameters are slurry concentration of 60 g/L, stirring speed of 1800 r/min and aeration rate of 0.18 m³/h. Compared with the samples without ultrasonic pretreatment, the refined mineral yield increased by 8.39%, the recovery rate of combustible material increased by 13.40%, and the ash content decreased by 4.72%. Particle size composition, FTIR, XPS, SEM and BET were used to analyze the changes of physicochemical properties before and after ultrasonic pretreatment, and the mechanism of ultrasonic in coal gasification fine slag flotation was clarified. The particle size composition analysis showed that the coarse particles decreased, the fine particles increased and the ash content decreased after ultrasonic pretreatment, indicating that the fine slag of coal gasification was broken and dissociated to a certain extent. SEM and BET analysis showed that after ultrasonic pretreatment, the pore structure of the residual carbon particles was complete, the surface was smooth, and the high ash impurities attached to the surface or pores of the residual carbon particles were reduced, which exposed the fresh surface of the residual carbon particles. XPS analysis showed that the content of polar oxygen-containing functional groups on the residual carbon surface decreased after ultrasonic pretreatment, which enhanced the hydrophobicity and floatability of the residual carbon surface. It is produced by dissociation of water molecules in pulp after ultrasonic pretreatment. OH free radical electrons form OH -, resulting in the increase of pulp pH value, weak alkali environment is conducive to coal gasification fine slag carbon ash separation.

Secondly, the influence of ultrasonic pretreatment of collector on the flotation of fine slag of coal gasification was investigated. The optimal ratio of water: diesel :Span80:Tween80 in phacoemulsification collector is 60:24:14.4:1.6; The optimal ultrasonic pretreatment power and time were 540 W and 6 min, respectively. Compared with the condition without ultrasonic pretreatment, the fine mineral yield increased by 19.98%, the recovery rate of combustible material increased by 27.15%, and the ash content decreased by 3.24%. FTIR analysis showed that no new absorption peak appeared before and after the action of the collector on the coal gasification fine slag, indicating that the adsorption of the collector on the surface of the coal gasification fine slag was physical adsorption. Laser particle size analysis showed that the particle size and dispersibility of the emulsified collector in water after ultrasonic pretreatment were significantly better than that of diesel oil. The analysis of induction time and flotation kinetics showed that the phacoemulsification collector could shorten the adhesion mineralization time between carbon residue particles and bubbles, and improve its floatability.

Finally, the influence of synchronous/step ultrasonic pretreatment of ash and slag samples and collector on the flotation effect of coal gasification fine slag was investigated. The best results were obtained when the power and time of synchronous ultrasonic pretreatment were 540 W and 9 min, respectively. Compared with conventional flotation, the fine mineral yield increased by 3.06%, the combustible recovery increased by 6.00%, and the ash content decreased by 4.70%. The best results were obtained when the power and time of stepwise ultrasonic pretreatment were 540 W and 11 min, respectively. Compared with conventional flotation, the fine mineral yield increased by 10.14%, the recovery rate of combustible material increased by 16.87%, and the ash content decreased by 6.88%. The recovery rate of flotation combustible in synchronous ultrasonic pretreatment is low. This is because the collision probability of particle and reagent is increased by synchronous ultrasonic pretreatment, but the structural stability will be deteriorated if the ultrasonic pretreatment time is too long. The properties of slurry and reagent reached the best during stepwise ultrasonic pretreatment, and the emulsified collector could better adsorb on the exposed fresh dissociation surface.

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