Synthesis and alteration of 3-octahedral clay minerals.

以秋田县塔卡诺苏的硅藻土和稻壳灰为原料，在几种水热条件下合成了高岭石和3-八面体蒙脱石。硅藻土合成高岭土的研究。硅藻土在AlCl3水溶液中的分散体在170~230ﾟC时生成高岭石，高岭石在170ﾟC下反应3小时开始生成。用差热分析和X-射线衍射法对其在合成产品中的产率进行了估算。在170ﾟC下180小时，高岭石的生成量约为10%，200ﾟC时约为30%，230ﾟC.2时为60%。从硅藻土中合成蒙脱石。(1)镁蒙皂石。用氯化氢处理过的硅藻土，在温度为200ﾟC、硅镁摩尔比为8：8~3的氯化镁水溶液中制备了镁蒙脱石。当原料的摩尔比为8：6时，生成蒙皂石和滑石；当原料的摩尔比为8：4.5时，生成的是蒙皂石和蛇纹石矿物。Si：Mg(摩尔比)=8：3的起始物具有很宽的基面反射。(2)镍钙钛矿。硅藻土研磨10小时(10-h)和30小时(30-h)。以硅藻土为原料，在200ﾟ的NiCl2(pH 13.50)水溶液中分散[硅：镁锂(摩尔比)=8：5.33：0.66]制备镍蒙脱石，反应3h开始生成蒙脱石。原料研磨30小时(30-h)比研磨10小时(10-h)更容易生成蒙脱石。利用稻壳灰合成3-八面体蒙脱石。稻壳灰可作为生产蒙脱石的优质硅质原料。最佳反应条件为：焙烧温度450ﾟC，硅：镁：锂(太阳比)=8：5.34：0.66，反应前分散体的pH值为13.2~13.5，反应时间为4天。

Kaolinite and 3-octahedral smectites were synthesized under several hydrothermal conditions from diatomaceous earth, which occurs at Takanosu, Akita Prefecture, and from rice husk ash.1. Synthesis of kaolinite from diatomaceous earth. Kaolinite has been prepared from dispersions of diatomaceous earth in aqueous solution of AlCl_3 at 170-230ﾟC. Kaolinite began to produce at 170ﾟC for 3 hours. Its yield in synthetic products was estimated by DTA and X-ray methods. For 180 hours, kaolinite was produced about 10 % at 170ﾟC, about 30 % at 200ﾟC, and 60 % at 230ﾟC.2. Synthesis of smectite from diatomaceous earth. (1) Mg-smectite. Mg-smectite has been prepared from the HCl treated diatomaceous earth in aqueous solutions of MgCl_2 at 200ﾟC in various Si : Mg molar ratios ranging from 8 : 8-3. Smectites were produces from the starting materials with Si : Mg (molar ratio) = 8 : 6. Smectites and talcs were produced from the starting materials with Si : Mg (molar ratio) = 8 : 8. Smectites and serpentine minerals were produced from the starting materials with Si : Mg (molar ratio) = 8 : 4.5. The starting materials with Si : Mg (molar ratio) = 8 : 3 altered spectites having very broad basal reflection. (2) Ni-seectite. Diatomaceous earth was ground at 10 hours (10-h) and 30 hours (30-h). Ni-smectite has been prepared from dispersions [Si : Mg Li (solar ratio) = 8 : 5.33 : 0.66] of the ground diatomaceous earth in aqueous solutions of NiCl_2 (pH 13.50) at 200ﾟC. Smectite began to produce from 3 hours treatment. Smectites were produced easier the starting material ground 30 hours (30-h) than that of 10 hours ground (10-h).3. Synthesis of 3-octahedral smectite from rice husk ash. Rice husk ash can be used as a superior siliceous material for production of smectite. The best condition is as follows ; Temperature of calcination : 450ﾟC, Si : Mg : Li (solar ratio) = 8 : 5.34 : 0.66, pH of the dispersion before reaction : 13.2-13.5, Reaction time : 4 days.