Research on an automatic flocculant dosing system based on the stirring and dissolution laws of APAM

The stirring and dissolution of flocculants are critical steps in the coal slurry water treatment process at coal preparation plants. To address the challenges of accurately controlling the dissolution quality and uniformity of flocculants, the lack of viscosity detection technology that balances effectiveness and real-time capability, and the insufficient research on flocculant dissolution and stirring equipment, an automatic flocculant dosing system based on the stirring and dissolution principles of anionic polyacrylamide (APAM) is proposed. The system consists of three parts: quantitative dosing and conveying, pneumatic dispersion, and viscosity detection and stirring, with intelligent control achieved through a PLC and an upper computer. Based on the mechanical stirring power formula and Nagata Sadaharu's power number, the mathematical relationship between stirring power and the kinematic viscosity of APAM solution is derived. Experimental methods are used to investigate the dissolution patterns of APAM with different molecular weights (4 million, 8 million, 12 million, 16 million, 18 million, and 20 million) at stirring speeds ranging from 200 to 1 000 rpm. A mathematical model linking kinematic viscosity and stirring power is established, and the effectiveness of the system and model is verified through simulated field tests. The results show that the kinematic viscosity of the APAM solution initially increases and then decreases with increasing stirring power, with an optimal stirring power corresponding to the maximum kinematic viscosity. Based on the derived mathematical model, the average relative error between the kinematic viscosity calculated from stirring power and the actual measured values is less than 6%. The designed automatic dosing system enables non-contact, real-time detection of the kinematic viscosity of APAM solution, operates stably, is easy to use, and effectively controls the viscosity of the flocculant solution. This system and the derived mathematical model address the precision issues of traditional dosing methods, enhance the intelligence and reliability of flocculant addition in coal slurry water treatment, and provide theoretical guidance for optimizing flocculant dissolution parameters.