Study On Preparation,Property And Application Of Lithium Montmorillonite

Lithium montmorillonite is a sort of new manmade montmorillonite material, whose raw material is calcium bentonite. Lithium montmorillonite has some special properties, which are different from those inorganic montmorillonite. Its special properties bring lithium montmorillonite a broad applied prospects, it can be used in the field of foundry coating and new electric material. Hence, the synthesis and application of lithium montmorillonite have become an important way of enhancing added value of bentonite. The aims of this study are to find out the optimum synthesis process parameters of lithium montmorillonite, to learn the changing rules in property and structure of lithium montmorillonite in heating treatment, and to study in the application property of lithium morntmrillonite.In this paper, the optimum synthesis processing parameters of lithium montmorillonite has been studied systemically. The studies contain four main aspects, which are the lithium modifying methods, the categories of montmorillinites, the categories of modifying agents and the process parameteres, such as the dosage of modifying agent, the reaction time and the reaction temperature. At the same time, this paper gives a new method to test the special property of lithium montmorillonite, which is named ethanol- swell-value.Constant temperature water-bath, high speed dispersion machine and ultrasonic machine were used to study on the influence of modifying methods on the properties of synthesized lithium montmorillonite. Researches show that all these three machines can be used to synthesize lithium montmorillonite, and the properties of synthesized lithium montmorillonite are similar. But the constant temperature water-bath way is more geniality than the others, so the constant temperature water-bath way was choosed in this experiment. Two categories of calcium montmorillonite (WF and LX) are used to synthesize lithium montmorillonite. Researches show that the properties of lithium montmorillonite synthesized by WF calcium montmorillonite are much better than those synthesized by LX calcium montmorillonite. Three kinds of modified agents (LiCl, Li₂CO₃, Li₂CO₃ and oxalic acid mixed leechdom) are choosed to synthesize lithium montmorillonite; researches show that the mixed leechdom is the best modifying agent among others. By the single factor experiments and orthogonal experiment, the optimal conditions of synthesizing process were gotten. Constant temperature water-bath is the choosen machine, row material is WF calcium bentonite, modifying agent is the mixed leechdom (Li₂CO₃ and oxalic acid), the dosage of modifying agent is 6%, the reaction temperature is 60°C, and the reaction time is 1h. At the optimum condition, the properties of synthesized Lithium montmorillonite are showed below. The swelling value is 98ml/3g, the colloid index is 100mL/3g, and the ethanol-swell- vale is 88mL/3g.Study on the structure and property changing rules of lithium montmorillonites, which were heated in different high temperatures. Researches show that with the increase of heating temperature, the properties of lithium montmorillonite change distinctly. When the heating temperature reaches 130°C, lithium montmorillonite loses its swelling property in water, its swelling value is l-2mL/g, colloid index is 7-8mL/3g. When the heating temperature reaches 200°C, lithium montmorillonite loses its swelling property in ethanol, and its ethanol swelling value descend to 20mL/3g. Through XRD and IR analytical method, the researches show that the exchangeable ions (Li⁺) can migrate from the interlayer space into the structure of montmorillonite. Accomany with the increase of heating temperature, Li⁺ ions migrate into the oxtahedral vacancies first, when the fixation reach its maximum value, Li⁺ ions migrate into the tetrahedron vacancies. When the heating temperature reaches 500°C, a new phase appears in lithium montmorillonite.Study on the application of lithium montmorillonite in the field of foundry coating. Two aspects of lithium montmorillonite are studied there, which are property and dosage. Researches show that lithium montmorillonite with high swelling value, high colloid index and high ethanol-swell-value has a much better applied property in the field of foundry coating, and the optimum dosage is 2%.Generally speaking, through analyzing the lithium modifying methods, the categories of montmorillonite, the categories of modifying agent, and the process parameters influence rules, the optimization synthesis process was gotten. By heating treatment experiments, the structure and property changing rules of lithium montmorillonite were clarified. By application experiment in foundary coating, it was indicated that lithium montmorillonite has a better application property. All these researches give some theoretical supports for the synthesis and application of lithium montmorillonite.