With the continuous development of application of new energy materials in China, lithium batteries are also more and more widely used as green energy sources. Lithium salt manufacturing enterprises also ushered in the rapid development. The demand for advanced technology, high automatic equipment are also more urgent.
In the traditional lithium hydroxide preparation process, the acidified, roasted and cooled β-spodumene powder is stirred at a liquid-solid ratio of 1:3 in astirring tank, and then the fully-stirred sulfuric acid solution is beat into a cooling kettle with a jacket. Through the heat exchange between the stirring solution and cooling liquid in the jacket to produce lithium hydroxide grains. During the process, the inner wall of the cooling kettle will freeze due to excessive temperature difference, and the heat exchange rate of the inner wall would rapidly decreases after freezing, thereby reducing the heat exchange efficiency. The crystallization process is not easy to control because the temperature is not uniform, the crystal size distribution is wide, with more fine crystals, which would affect the subsequent collection of lithium hydroxide.
Through the design and optimization of lithium salt preparation process, the cooling kettle equipment is optimized, and a better frozenstirred tank was designed. First of all, according to the icing phenomenon of the inner wall of the stirring tank, thestirring blade is designed as a frame-type structure, and awear-resistant scraper is mounted on the stirring frame. The gap between the inner wall of the scraper and the stirring tank is adjusted to about 1mm. The the low-temperature solution of the inner wall and the center solution are rapidly stirred by rotary of the stirring blade, so that the solution is cooled evenly. When the inner wall produces ices, the wear-resistant scraper would quickly strike off the ices to keep the heat exchange of inner walluniformly and reliably. In addition, a spiral vane is arranged in the stirring jacket of the cooling tank, to make the cooling liquid spirally flow along the outer wall of the tank so as to keep the temperature of the inner wall, so that the solution would rapidly cooled.
The improved freezing and stirring tank can continuously feeding and discharge, with stable product quality, uniform grain size, less fine crystal, and high leaching efficiency, which make sure the preparation of the lithium hydroxide is more complete and reliable.
Special freezing stirring tank