The Development Of Recycling System For Dangerous And Low-grade Mg Scrap

With the rapid development of Mg industry, more and more Mg scrap are produced, within which, dangerous scrap of fine size and low-grade scrap (such as slag etc.) cannot be recycled to date by existing mature technologies. Therefore, the present study was devoted to develop a new technique and equipment for the recycling of dangerous and low-grade Mg scraps produced in Mg industry.To lay a theoretical base for the development, the recycling theory was analyzed from the viewpoint of vacuum distilling thermodynamics and kinetics and the relationship of boiling temperature and pressure, and its effect on distilling process were discussed in accordance to Mg 3-phase equilibrium diagram. Then, the processing parameters of the recycling process were proposed and the energy consumption of the process was calculated in contrast with Mg thermal reduction. Finally, the feasibility and cost efficiency of the process were addressed.After the design of the vacuum pipe system, the requirements of the process on the vacuity and temperature were analyzed, the control hardware system was designed based on Siemens S-200 PLC and touch sensitive screen. Then the control software was developed based on the modern control theory. To precisely control the distilling temperature, the thermal balance of the system was analyzed, and the thermal transfer function was deduced, and a special fuzz-control software was developed to meet the need of a successful distilling processing on a new PID control method.After the construction the recycling system, the control software was debugged in both virtue and real processing environments. After some improvement and modification, the system began to work properly with satisfaction.