Functional waveform pulse variable speed stirring to improve mechanistic analysis and experimental study on the purification efficiency of zinc sulfate solution

Abstract This paper builds a wireless precision control function waveform pulse variable speed stirring device with point-to-point data transmission between the host computer and the microcontroller, which uses a programmable STM32 microcontroller as the system controller, superimposed with a single closed-loop static differential-free speed control system and a pulse broadband modulation (PWM) system to control the DC brush motor driving the stirring paddle based on arbitrary waveform function variable speed stirring respectively. The effects of different pulse waveform stirring systems on the purification effect of Cadmium ions (Cd 2+ ) from zinc sulfate solution were studied under the same pulse period and maximum speed. The experimental results show that when K P = 0.012 and T i = 100, the anti-disturbance of the motor during the variable speed stirring process can be effectively improved, and the speed adjustment time is short and robust; when the Cd 2+ purification rate reaches 92%, the purification time of the variable sine function stirring system is shortened by about 40% compared with that of the uniform speed stirring system, and that of the variable trapezoidal function stirring system is shortened by about 33.3% compared with that of the uniform speed stirring system. When the reaction is finished, the Cd 2+ concentration is reduced to 6 mg/L by the variable sinusoidal stirring system only, and the Cd 2+ concentration is lower than 10 mg/L in a shorter time compared with the time required for cadmium removal in the actual industrial production line.