Design And Development Of Model Software Of Processes Of Slurry Neutralization,Sedimentation And Separation

As a very efficient way, hydrometallurgy is widely used in the mineral process to get valuale things from low-grade ores. This method can improve recovery of metals, be beneficial for environment and make the produation process continuous and automatic.Processes of slurry neutralization, sedimentation and separation play an important role in hydrometallurgy and the aim of these processes is to separate the alkali of crystal out from their orginal state (metal ions). However, these processes are characterized by frequenty changed modes, multi-variable, strong coupled, strong nonlinearity, large lag and nondeterminism etc. Thus it’s difficult to achieve optimal control and to ensure the process stable and efficient. To improve product quality and production efficiency and offer a research platform for analysis and design control system, the dynamic models are established in this thesis supported by the Northeastern University "985Project" Process Industry Integration Automation Innovation Platform Project. In addtion, simulated research of these models is done.The main work is illustrated as follows:(1) The dynamic mechanism models of slurry neutralization, sedimentation and separation are established. Initially, these processes are well analyzed in a mechanical way. Then dynamic mathematical models of the first stage and the second stage of neutralization process are established according to ion conservation and solubility product equilibrium constant. These models can be used to describe the relationship between the input variables (i.e. the flow of incoming solution, the flow of seed slurry and the flow of lye) and the output variables (i.e. the pH value of neutralization tank and the crystal weight of neutralization tank export). Meanwhile a dynamic mathematical model of thickening process is also established using the mass conservation, Stokes law and Keer Sen law, and it can describe the relationship between the input variables (i.e. the flow of slurry, the flow of flocculant and the flow of underflow) and the output variables (i.e. the height of the interface of soil layers and the bottom flow concentration). The dynamic mechanism model of the whole process can be obtained by integrating the three models above.(2) A real-time simulated software of slurry neutralization, sedimentation and separation is designed and developed based on Honeywell PKS C300, VBscript and MATLAB. The software has the function of dynamic process simulation, simulation variable step size, the selection of simulation process, the simulation process control, operating parameters and boundary conditions changing online etc. The software consists of the process flow interface, the parameter setting interface, trend interface, background model and solution arithmetic program, communication interface between foreground and background.(4) Some step response experiments, such as changing operator variable and boundary condition, are done on the realtime simulation software to observe the dynamic characteristics of these processes. The correctness and effectiveness of these dynamic models are validated by these experiments from the perspective of mechanism of theses processes.