Research On Rare Earth Extraction Process Control Method Based On Video Surveillance

Rare earth is composed of Lanthanides, Scandium and Yttrium a total of 17 elements. There exists abundant rare earth resource in mainland of China. Reserve and production of the rare earth occupy the primary position in the world. Rare earth is indispensable industrial raw material in the production of display phosphor, NdFeB permanent magnet, Ni/MH battery, rare earth aluminum alloy, precision ceramics etc. With the industrial production of rare earth will large-scale, centralized and continuous, it urgently demands an efficient, stable and automated production line.Due to a smaller separation factor between adjacent elements, purification of rare earth elements needs more extraction series. The regulating effect of the extraction process inputs, such as extractant flowrate, material liquid flowrate and acid flowrate, usually needs hours or even tens of hours to influence the hard-extracted and easy-extracted component content of water phase exit and organic phase exit. And any one of the input flowrate is changed, it will impact the two exits element component content. That is to say there exists nonlinear, large time delay, strong coupling between element component content and extraction process inputs flowrate. However, when the distribution of easy-extracted and hard-extracted components changed, the rare earth ions characteristic color will move back and forth. And the movement of rare earth ions characteristic color is intuitive, also measurable. Generalized predictive control (GPC) could predict the output of multi-step mode in the future, and the controlling keeps the multi-step function in multi-step intervals. Fuzzy control bases on fuzzy set theory, and introduces man's fuzzy decision-making and reasoning function in the control. Therefore, plenty of accumulated practical experience (Expert Control Rules), through the fuzzy inference and defuzzification, can transform into a precise controlling quantity, in order to achieve automatic control of the extraction process. The main works are as follows:(1) It has a more indepth research of the whole extraction process. First, it describes the separation of rare earth extraction process, and analyses the mechanism of the extraction process. And then, a discussion of the rare earth extraction process automation is proposed in this paper. Finally, according to the current research, it summarizes the problems of rare earth extraction separation.(2) When the separation process conditions change, the distribution of easy-extracted and hard-extracted components will be changed, and the rare earth ions characteristic color will move back and forth. Using the video surveillance, taking the color band changing fast point and its vicinity as monitoring points, and then using image processing technique, the color band offsets will be identified. Experimental results show that, regardless of the rare earth ions characteristic color band moving forward or backward, the offset series can be accurately distinguished.(3) Using the obtained offsets of the rare earth ions characteristic color, the GPC and fuzzy control are used in rare earth extraction separation. The simulation results show that the two control strategies are effective, and ensure the final exits purity of component content of the rare earth extraction.