【作者】 姚志通；

【导师】 叶瑛；

【作者基本信息】 浙江大学 ， 矿物学、岩石学、矿床学， 2010， 博士

【摘要】 本研究着力解决固体废弃物粉煤灰的资源化利用难题。以杭州热电厂和半山电厂粉煤灰为例,首先对比研究了循环流化床锅炉脱硫灰(CFB灰)和普通煤粉锅炉粉煤灰(PC灰)的特性；然后针对普通粉煤灰的特性,进行干法脱铁和湿法除炭预处理；最后对粉煤灰进行综合利用研究,主要包括以粉煤灰为原料制取白炭黑、氧化铝,合成沸石分子筛以及制备微晶玻璃等.主要研究内容和结果如下：(1)对比研究了脱硫灰和普灰的特性,研究结果表明：脱硫灰烧失量、氧化钙含量相对较高.普灰以莫来石和石英为主相,含有较高的无定形相;脱硫灰则以石英、方解石和硬石膏为主相,玻璃相少见。SEM观察发现,普灰颗粒以规则球形为主,而脱硫灰几乎无球形颗粒。(2)粉煤灰干法磁选脱铁结果表明,分析仪倾角和电流强度分别为30°和2.5A时磁选效果最好.与粗选工艺相比,粗选-扫选工艺较粗选-精选脱铁率提高明显。磁性颗粒主相为石英、莫来石和磁赤铁矿相。粉煤灰湿法除炭结果表明,捕收剂为轻柴油用量800g/t时,除炭率高达82.53%.起泡剂为仲辛醇用量600g/t时,除炭率可达80.03%.物相分析显示浮选产物主要为炭,同时夹杂有少量莫来石.炭粒微观形貌呈多孔球状,与玻璃、硅酸盐呈连生体产出。(3)粉煤灰碱融实验表明,同时添加助剂碳酸钠和氯化钠可有效降低粉煤灰的晶相转变温度。实验接着以粉煤灰碱融物为原料,分别通过盐酸酸浸和氨水沉淀法制取了白炭黑和γ-Al2O3. TG-DTA和SEM分析表明,γ-MPS对白炭黑的改性效果优于硬脂酸。实验后续还以制备的沉淀SiO2为硅源,采用化学包覆法成功制备了硅钛复合物。(4)以粉煤灰为原料,分别采用水热法和碱融法合成了方钠石和钾霞石。方钠石为规则球形,钾霞石颗粒表面生长有大量立态生长的片状结晶。TG-DTA分析表明,合成的沸石产物均具有良好的热稳定性.水煮侵蚀实验说明钾霞石具有较高的钾保持率。实验还研究了粉煤灰在LiOH·H2O碱液中的水热反应行为,并以碱融法合成了Li-ABW沸石。(5)以粉煤灰和LiOH·H2O为原料制得Li2Al2Si3O10为主晶相的微晶玻璃。SEM观察发现,产物颗粒相互紧锁,形成烧结完好致密化的微观结构。研究还以粉煤灰和(MgCO3)4·Mg(OH)2·5H2O为原料,采用固态烧结法制备了α-堇青石,并探讨了LiOH·H2O和TiO2对堇青石烧结性能的影响。当LiOH·H2O添加量为10%时,β-锂辉石固熔体和尖晶石相开始形成。扫描电镜观察发现,随著Li+离子掺入量的增多,晶体轮廓逐渐光滑；同时增浓作用增强,试样气孔和微晶体粒度明显减少。当Ti02添加量从4%增至10%时,Low quartz和Rutile相开始形成,同时堇青石和尖晶石含量有所降低。更多还原

【Abstract】 This study was aimed to settle the utilization problem of solid waste coal fly ash. Taking fly ash from Hangzhou thermal power plant and banshan power plant, firstly the characterization of two different ashes, namely desulfurization ash derived from circulating fluidized bed boiler (CFB ash) and pulverized coal ash (PC ash) were studied. Then, the dry process iron removal and wet process carbon separation were conducted based on the characterization of the PC ash. Its comprehensive utilization was studied at last, which included the preparation of precipitated silica and aluminium, synthesis of zeolite molecular sieves and the preparation of glass-ceramic. The main contents and results were as follows:(1) The characterization of CFB ash and PC ash were comparatively studied and the results were as follows:The loss on ignition (LOI) and CaO contents of CFB ash were higher than that of PC ash. The main phase of PC ash was mullite and quartz, including large quantity of amorphous phase. As compared, the main phase of CFB ash was quartz, calcite and anhydrite with small amount of glass phase. The SEM observation revealed that the PC ash manifested as regular sphere-like particle, while the regular particle was rare to be observed in the CBF ash.(2) The results of iron removal by magnetic separation experiment showed that the magnetic separation efficiency was higher when the dip angle and current intensity of the analyzer was 30°and 2.5A, respectively. Compared to roughing dressing, the iron removal efficiency of roughing-scavenging dressing was higher than that of roughing-fine dressing. The main phases of magnetic particle were quartz, mullite and maghemite. The study of wet process carbon separation indicated that the carbon removal efficiency attained 82.53% when the dosage of light diesel oil collector was 800g/t. The removal efficiency was 80.03% when the amount of sec-octyl alcohols was selected as 600g/t. The phase analysis of floated product showed that carbon was the prevailing phase with little amount of mullite. The carbon was an intergrowth of glass and silicate manifested as spherical porous shape.(3) The results of alkaline fusion study showed that the phase transformation temperature decreased after adding sodium carbonate and sodium chloride into the coal fly ash. Thereafter, the precipitated silica andγ-Al2O3 were prepared using the alkaline fused product as material through hydrochloric acid extracting and ammonia precipitation method, respectively. The TG-DTA and SEM analysis indicated that the y-MPS showed good modification effect on precipitated silica compared with that of stearic acid. At last, the titania-silica composite was successfully prepared using precipitated silica as the silica source by chemical coating method.(4) The sodalite and kaliophilite were prepared using coal fly ash as material by hydrothermal and fusion method, respectively. The synthesized sodalite was regular sphere shape. As compared, there were many plate-like crystals developed on the surface of kaliophilite particle. The TG-DTA analysis showed that the synthesized zeolites had remarkable thermal stability. The leaching test confirmed that the kaliophilite possessed high potassium retention rate. The hydrothermal treatment of coal fly ash in LiOH·H2O alkaline solution was also studied and the Li-ABW zeolite was synthesized by fusion method.(5) The glass-ceramic with major phase Li2Al2Si3O10 was prepared through sintering coal fly ash with LiOH·H2O powder. SEM observation revealed that the product particle interlocked together with dense well-sintered microstructure. The a-cordierite glass-ceramic was also prepared by solid state sintering method using coal fly ash and (MgCO3)4·Mg(OH)2·5H2O powder as precursors. As the LiOH·H2O additive amount reached 10%,β-spodumene and spinel phases developed. SEM observations revealed that the contour of crystal grains became smooth with the doping of Li+ion. In addition to this feature, the densification process improved and the sample’s porosity and grain size decreased notably. As the TiO2 contents increased from 4% to 10%, low quartz and rutile were formed. Simultaneously, the amounts of indialite and spinel decreased.更多还原