通过化学成分分析、岩矿鉴定、扫描电镜、X射线衍射、红外光谱和差热一热重曲线观察和分析测试,对龙岩高岭土的矿物学特征进行了研究.结果表明,龙岩高岭土矿物组成简单,主要由高岭石组成,有害成分铁和钛含量很低,自然白度83%～92%,质量好,但高岭石结晶程度不高,Hinckley指数0.42,属较无序高岭石.在此基础上,用醋酸钾对高岭石进行插层,研究插层对高岭石微结构的影响.XRD 分析显示,高岭石与醋酸钾作用后,d001 值由原来的0.722 3 nm增至1.392 9 nm,表明醋酸根已插入高岭石层间,并使高岭石的层间距被撑大,插层率可达90%以上.红外分析也证实,醋酸根和水一起插入高岭石层间;高岭石与醋酸根之间已形成多种形式和强度的氢键,而且内羟基也受到一定程度的扰动,说明水和醋酸根插入高岭石层间,与高岭石有较强的键合作用.%This paper studied the mineralogical characteristics of kaolin from Longyan by means of chemical analysis, mineral examination, SEM, XRD, IR and DTA-TG.It is shown that the content of Al2O3 and SiO2 is very close to the theoretical value, with tiny content of Fe and Ti.The content of K2O is higher because of residual mica.The results also show that Longyan kaolin is made up of kaolinite with minor mica and a very small amount of quartz, and its natural whiteness varies from 83％ to 92％.The SEM photographs of Longyan kaolin show clear layer structure 0.1 ～5 μm in size, and a small amount of rod-shaped kaolinite.The laser particle size analyzer measurement results of Longyan kaolinite shows that 83.2 ％ particles are between 1.00 and 5.00 μm in size, with an average of 3.16 μm.The main bands of XRD pattern of Longyan kaolinite are 1.004 nm, 0.722 nm,0.447 nm,0.359 nm,0.335 nm,0.257 nm,0.250 nm and 0.235 nm.A comparison with the standard spectrum shows that kaolin is the main mineral component of Longyan kaolin.The 1.004 nm band is attributed to halloysite or mica.Combined with SEM results, these data indicate that Longyan kaolinite contains small amounts of halloysite, and the 0.335 nm band is attributed to quartz.Its lower crystallinity index (HI = 0.42) suggests that Longyan kaolinite is a relatively disordered kaolinite.FT-IR spectra imply that the functional groups of kaolinite layer structure remain perfect, but the intensity of 3695.39 cm-1 band (inner surface hydroxyl stretching vibration) is 1.10 times that of 3620.26 cm-1 band (inner hydroxyl stretching vibration), which indicates that the crystallinity of Longyan kaolinite is relatively low.TG results show that the weighloss at 100 ～ 800℃ is 11.33％, almost equal to the theoretical water content (10.8％).This also proves that the content of impurities of Longyan kaolinite is tiny.In the present experiments, the Kln-KAc intercalates were investigated to study the relationship between the microstructure and the intercalation.XRD data show that potassium acetate could directly insert between the inner layers of kaolinite.As a result, the c-axis spacing (d001) of KlnKAc intercalation composite increased from 0.7223 nm to 1.3929 nm of kaolinite, and the intercalation rate could reach over 90％.There were four new bands, 1605.22 cm-1, 1566.33 cm-1, 1416.57 cm-1 and 1344.99 cm-1, on the FT-IR spectrum of Kln-KAc, which indicated that potassium acetate inserted the inner layers of kaolinite.IR analysis showed that the band of inner surface hydroxyl and inner hydroxyl stretching vibration became greatly weaker, and moved towards low wavelength.Synchronously, the appearance of the band at 3604.68 cm-1 was corresponding to the hydrogen bond formed between acetate ions and the inner surface hydroxyl of kaolinite.DTA curves of Kln-KAc indicate the endothermic peak was at 562.05℃, which was attributed to the fact that dehydroxylation became obviously weaker.These data indicated that the microstructure of hydroxyl was destroyed to a certain extent because of the insert of acetate ions.These results indicate that acetate ions insert between the inner layers of kaolinite under the participation of water, and different intensities and types of hydrogen bonds exist between acetate ions and the inner surface hydroxyl of kaolinite.
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