The development of vacuum crystallization process technology in the production of titanium dioxide bookmark0 Dai Jianjun (Zhuzhou Chemical Industry Group Yongli Co., Ltd. °412004) Dai Jianjun: Engineer, has been engaged in titanium dioxide production. Technical innovation and technology management.
The crystallization process has low investment and operating costs compared to the traditional freeze crystallization process. High crystallization efficiency. Large production capacity. Energy saving and other advantages.
0 cited hundreds of China's titanium dioxide industry has made rapid development in recent years, production capacity over Japan, ranking second in the world. However, compared with the advanced level in foreign countries, there is an anatase titanium dioxide and a non-pigmented titanium dioxide in the titanium dioxide industry in China with many production plants, small production scales, poor production technology, single products, and most of the low-grade titanium dioxide. The key to the development of titanium dioxide is urgently needed for the industry to improve the technical level and bring the economies of scale into full play.
Zhuzhou Hualien Wynn Titanium Dioxide Factory is one of the earliest producers of pigment titanium dioxide in China. The existing 15,000 t/a production capacity has an important position in the domestic titanium dioxide industry. Considering the development of the titanium dioxide market, expanding production capacity and developing high-grade rutile titanium dioxide products are necessary conditions for our company to gain a foothold in the market and gain advantages in competition. In the course of technological transformation, only relying on technological progress and constant innovation can promote the improvement of titanium dioxide production technology, shorten the gap with foreign products, and maintain the domestic leading position.
In the production process of sulphate titanium dioxide, our company and most domestic manufacturers adopt the freezing crystallization process, but vacuum crystallization is more advantageous than freezing crystallization in all aspects. Therefore, our company adopted the method of development research and self-design in the technological transformation of titanium dioxide, successfully developed the vacuum crystallization technology and domestic equipment, formed its own vacuum crystallization technology, and promoted the improvement of the overall production technology level of titanium dioxide in China. .
1 vacuum crystallization process technology principle, application status and development trend Vacuum crystallization, steam as the power, it is ejected at high speed by the jet pump, the static pressure can be converted into kinetic energy to generate vacuum, in the vacuum crystallization tank in the titanium liquid The water vaporizes under the reduced pressure and the heat is removed from the vaporized heat, so that the temperature of the titanium liquid is reduced, and the ferrous sulfate crystallizes out. The degree of supersaturation of the continuously evaporated solution of water also increases, and the ferrous iron continuously precipitates until the desired temperature and allowable ferrous content are reached. The vacuum crystallization process is an advanced titanium liquid purification technology. The foreign large-scale sulfuric acid titanium dioxide plants have adopted the vacuum crystallization process, and the domestically introduced three sets of foreign advanced 15,000 t/a titanium dioxide production devices (Titanium Dioxide, 404 The plant and Jinan Yuxing used vacuum crystallization process. Titanium dioxide industry is characterized by a high degree of monopoly of production technology and high technology transfer costs. At present, the complete set of equipment for the vacuum crystallization process, including vacuum crystallization tanks and steam jet pumps, has no mature domestic experience. Key equipment needs The investment of foreign escape devices will be greatly increased, which has limited the promotion and application of vacuum crystallization technology in domestic titanium white enterprises. The vacuum crystallization process of the domestically-developed devices developed by our company is conducive to reducing energy consumption, saving operating costs and promoting the industry, and has a good prospect for development.
2 The main contents, key technologies and innovations of vacuum crystallization technology development 2.1 The main contents of the implementation The vacuum crystallization process (attached) and technical parameters are determined; the selection, design and equipment of the main equipment are developed locally; the application of titanium dioxide in technological transformation The process, the construction of two sets of vacuum crystallization device.
2.2 Technical key points and innovation points determine the technical parameters in the process. The key equipment such as vacuum crystallizing tanks and stirring, jet pump design and selection and production are the key to the technology. It is an innovation of the project to replace imported equipments with self-designed or domestically-made equipments. point.
2.3 Effect After the process device is put into use, it can be successfully applied to the crystallization of ferrous iron in titanium dioxide production to meet the titanium white production process requirements. The new device meets the production capacity of titanium dioxide of not less than 15,000 t/a.
3 Comparison of vacuum crystallization and frozen crystallization Vacuum crystallization has advantages in investment cost, production process, energy saving and consumption, and operation method compared to traditional freezing crystallization (see the frozen crystallization process flow). The specific comparison is as follows: 4 Economic and Social Benefits Table 1 vacuum crystallization and freezing crystallization process comparison project vacuum crystallization capacity of freezing crystallization device / million t/a1.51.5 investment cost / million 221.5585. 89 (original value of assets) industrial water 12t1296 yuan 50 2kWDh112.5 yuan line (with / tTi2 steam 1.5t1062 yuan / / fee) other (oil, liquid ammonia, etc.) / 5.2 yuan total use 150.43 yuan 171 75 yuan annual consumption / million 225.6425762 equipment depreciation and maintenance / million yuan 35.869374 total / million 261 5035136 crystal efficiency decreased crystallization Tank pressure to reduce the temperature of titanium, high crystallization efficiency of chilled water through the coil to indirectly reduce the temperature of the titanium liquid, the crystallization efficiency is low, the crystallization capacity is 25m3 per tank, the crystallization time is 253.5h, and the titanium liquid is 13m3 per tank. 12h crystal particles titanium liquid temperature gradually reduced, conducive to the growth of crystal nucleus, crystal particles frozen water and titanium liquid temperature difference, partial quenching stirring uneven, uniform size, but fine (solvable ) Crystallization of titanium particles after inhomogeneous crystallization Crystallization of large amounts of water evaporates during the crystallization process. The concentration of titanium solution can reach as low as 170g/L. Usually 140150g/L is due to the high concentration of titanium liquid, which increases the ability of the subsequent concentration process to produce energy. Saving steam 0608VfTi 20,000 yuan more than the annual savings 63.771994-2016ChinaAcademicournalElectronicPublishingHouse.Allrightsreserved, http:// 4.1 in the production of titanium dioxide vacuum crystallization process of domestic development success will promote the technical progress of titanium dioxide production in China, for the development of titanium dioxide device in China to create capacity Conditions.
4.2 Our company has developed and applied 2 sets of vacuum crystallization devices, with a capacity of 15,000 t/a compared to the traditional frozen crystallization process with the same capabilities, and reduced investment costs by 3.6439 million yuan. The total production capacity of ferrous ferrous smelters satisfies the need for the next step in the expansion of titanium dioxide to 20,000 t/a, and has created conditions for improving product quality.
4. The vacuum crystallization device saves energy and has low operating costs. Our company saves energy consumption by 637,200 yuan/a and saves operating expenses by 889,600 yuan/a. The total annual economic benefit is 1.5356 million yuan.
4.4 At present, there are more than 50 titanium dioxide manufacturers in China, and most of them still use traditional frozen crystallization. Therefore, the vacuum crystallization process and the localization of the device have great promotion value. At the same time, the process and device can also be applied to the concentration of about 20% of the waste acid from the titanium dioxide by-product. After the waste acid is concentrated, it can be used for the production of titanium dioxide or for the production of phosphate fertilizer. The headache of environmental protection in titanium dioxide production is solved. problem. In addition, the device has great promotion value in the relevant industry's thickening process
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