Design And Development On The Software Of Computer Control System For Large Floatation Process

The proportion of mineral resources with the feature of low-grade, finely-dissemination particle and complex mineral composition, is increasing in the world. The separation and purification of fine refractory ore has become one of the urgent problems in mineral processing industry at present. Floatation is an important means in the process of sorting fine-grained minerals, using the hydrophobic ability of the particles according to the difference on the surface of physicochemical properties. It can obtain high concentrate grade and low tailing grade through the separation of useful minerals and gangue minerals, by means of the buoyancy of bubbles in the ore slurry. With the enlargement, serialization and centralization of beneficiation industrial production in China, existing manual control mode has been unable to meet production requirements. Because the subjectivity and randomness of manual operation, consequently accidents such as froth overflow and no foam would occur, which lead to fluctuation of product quality, high reagent consumption, low concentrate grade and low metal recovery. So there is an urgent need to adopt a certain degree of control technology, to increase the level of automatic control, to stabilize the technology indicators, to reduce consumption of floatation process, and to increase the economic and market competitiveness ultimately.Based on the project "Process Control Technology Research of Short Column Process " supported by "Eleventh Five-Year" national plans, and the project of "Purifying Red Mine with Floatation Column for Nanfen concentration plant ", the software of computer control system for floatation process is designed, developed and tested. The software aims to maintain the stability of the important process parameters in the floatation process, and to maintain stable operation of important production equipments. The content of this paper are summarized as follows:(1)Combining with the process flow of flotation process, the influence on the concentrate grade and tailings grade by the major factors is analyzed at first, such as the slurry consistency, the ore particle size, the ore flow, the level of floatation, and the drug dosage of floatation process.(2)Through analysis of the relationship between the process technology indexes and the factors, and the actual floatation process flow, the main influencing factors and control objectives are extracted. Then, according to the characters and targets of control, a control method for the flotation process is developed, including loop control of the slurry consistency, loop control of the slurry mass, and switch control of the floatation drug dose. At the same time, the parameters of the controllers in the control loops are tuned, and its effectiveness is verificated through simulation.(3)At last, the software of computer control system for floatation process is designed and developed, including process control software based on Siemens STEP7, and process monitoring software based on Siemens WinCC. The process control software aims to realize process control and logic control of floatation process, thus, to ensure the stability of important variables tracking their setpoints, and the normal start and stop of key production equipments. Process monitoring software aims to realize acquisition and monitoring of data via the upper computer, and to facilitate the operator to operate.(4)Taking the start of the underflow pump, the setting of the slurry consistency and the alarm of the roughing level for an example, the developed software has been tested, using the simulation software PLCSIM in STEP7to simulate running of S7-300CPU. The feasibility and effectiveness of the developed software is showed by the results.