Study On Barium Titanate Cleaning Production Technology

With the progress of science and technology, people have more and more requirement for barium titanate which is called industry pillar of electronic ceramic and hope get better quality. At present, barium titanate is obtained by chemical coprecipitation with TiCl4 in industry. This method not only has high preparing cost, a long production process, a large of molten slag and molten salt which is difficult to deal with, but also some dangerous and poisonous medium such as chlorine, carbon monoxide, titanium tetrachloride is involved during the production. Titanyl oxalate can be used for the synthesis of barium titanate. Based on cleaner production and cost saving, in this paper, it was prepared with sodium titanate, a intermediate products obtained during the process of high titanium slag with the NaOH roasting mthod proposed by Institute of Process Engineering, Chinese Academy of Sciences. In order to achieve the clean production of barium titanate, the main study contents and results are as follows:(1) The research obtained sodium titanyl oxalate trihydrate by leaching cheaper sodium titanate NagTi5O14 with oxalic acid under different conditions and the optimum process conditions were obtained:concentration of oxalic acid 4 mol/L, reaction temperature 80℃, reaction time 2 h. The composition and purity of the product acquired successfully by evaporation crystallizing was charactered by ICP, XRD, XRF, FTIR etc. Besides the temperature leaching kinetics was studied. The experimental results showed that the apparent activation energy is determined as 43.85kJ/mol, the leaching of titanium follows the shrinking wore model with surface reaction control.(2)The synthesis of barium titanate by oxalate coprecipitation method with potassium titanyl oxalate tihydrate was systematically researched. It obtained the optimum process conditions: Ba/Ti=1.00, concentration of barium chloride 0.5 mol/L, concentration of titanium tetrachloride 0.5 mol/L,10% excess of oxalic acid,0.5%PEG, reaction at 40℃, Calcined 2 h at 750℃.Mechanism of the synthesis and decomposition of the precursor was studied by XRD, FTIR, TGA etc. The effect of the surfactant on the dispersibility of product was discussed. All kinds of surfactant could effectively controlled agglomeration to some extent, nonionic surfactant worked best. Tetragonal p-hase barium titanate of 270nm with good dispersion was prepared at the calcination temperatures of 1200℃.(3)In this article, it studied the synthesis of barium titanate by oxalate coprecipitation method with TiCl4. The effect of Ba/Ti, the concentration of barium chloride and titanium tetrachloride, reactant applying methods, calcination time, calcination temperatures and heating rate on the granularity, morphology and crystalline form of the product were investigated. At the same time, the optimum process conditions were obtained. We could acquire the spherical cubic phase barium titanate with high purity, even size, primary particle size of about 150nm and agglomerate particles of 1.2μm by this method.High purity of trihydrate sodium oxalate titanium product was synthesized through the above research. Square phase barium titanate powder with high purity and fine was obtained with oxalic acid titanium salt as raw materials. These will serve as a theoretical underpinning for the clean process of barium titanate to realize the comprehensive utilization on titanium resources.