Design And Development Of Computer Control System For Continuous Countercurrent Decantation Process

In modern metallurgy industry, suspension obtained by using hydrometallurgical processes contains the residue after leaching the ore and the leaching solution. Usually suspension is unstable, and the solid particles in it can separate with the liquid under external force. Ore is leached after one or more times, then gone through the liquid-solid separation processes, debris has become the materials with no value of using and recycling, generally is discharged as a waste. Before discharging, debris usually is cleaned by sedimentation tank or thicker adopting continuous countercurrent decantation process, in order to clear useful material, and maximize the recovery of valuable substances.The good design and control for the continuous counter-current decantation process enhance the production efficiency can effectively. But to control these processes have many difficult problems, such as complicated technology and serious coupling and so on. Therefore, its automatic control using advanced control techniques is of great significance. We design and develop the control strategy and the computer control system on the background of the continuous counter-current decantation process of one big smelter. The primary works are as following:(1) On the analysis of the problems and difficulties in the actual production process, the control strategy for the continuous counter-current decantation process is researched, which includes process loop control, device logic interlock control. The process loop mainly includes liquid level of thickener overflow tank control system, thickener process control system. According with the thickener characteristic, the control strategy which integrated the PID control and Coordination control and decoupling control was raised, object model was built and parameter of controller was set. The device logic interlock control includes start and stop device, the interlock relations.(2) Considering the characteristics and the control requirements of the continuous counter-current decantation process, the two-layer architecture of computer control system for red mud separating and washing process is researched and developed, including PMS (process monitoring system) and PCS(process control system), and design the functions and platform. The computer control system for continuous counter-current decantation process was designed and developed. (3) Has conducted the experimental study and the function testing to the development of continuous counter-current decantation process computer control system.