Study On Plant-wide Optimization Methods For Hydrometallurgy

As one of the two extractive metallurgy technologies,hydrometallurgy is a process to extract and separate the valuable metal of raw mineral materials,which has the advantages of high metal recovery,good flexibility,less investment,quick effect and good recovery of associated components.Therefore,hydrometallurgy is more suitable for recovering low-grade metal resources and is an effective way to solve the problem of the metal mineral resources utilization in China.However,the optimization control technology in hydrometallurgy develops slowly,which leads to lower efficiency,higher resources consumption and unstable product quality.And it becomes a bottleneck for hydrometallurgy industrial development.To solve such a problem,this dissertation is on the background of hydrometallurgy production process in one gold smelting factory.First,according to the difficulties of on-line measuring the comprehensive production indices and various key technical indices in hydrometallurgy process,this dissertation establishes the plant-wide mechanism model of hydrometallurgy process.Then,on the basis of the mechanism model,this dissertation sets up the plant-wide optimization model of hydrometallurgy.And aiming at the existed problems when solving the plant-wide optimization for hydrometallurgy,a plant-wide optimization solution method is proposed by the decomposition based on the coupling relationship between manipulated variables.Finally,aiming to the hierarchical decision-making structure for procedure indices and manipulated variables in actual production management,a plant-wide hierarchical optimization method based on minimum consumption model is proposed.Moreover,aiming to the problem of numerous technical indices and coupling relationship between them when the plant-wide hierarchical optimization method is used to solve the plant-wide optimization problem of large-scale hydrometallurgy process,this dissertation also proposes a plant-wide hierarchical optimization method combining the decomposition based on the coupling relationship between technical indices for hydrometallurgy.In this dissertation,the main researches are summarized as follows:1.Starting from the basic principle of the typical procedures in hydrometallurgy process,including leaching process,filter washing process and cementation.The static plant-wide mechanism model for hydrometallurgy process is established by analyzing the relationships of material balance and energy balance.The main parameters of model are obtained using experimental analysis and identification.The validity of the model is verified by static experiments using practical data.2.On the basis of the mechanism model,the plant-wide optimization model for hydrometallurgy is established,where maximizing the comprehensive economic benefits per unit of time is taken as the objective and the sodium cyanide addition quantity of each leaching tank and the zinc powder addition quantity are taken as the decision variables,two-order oscillating Particle Swarm Optimization(PSO)algorithm is used to solve the established plant-wide optimization model,the results show the rationality of the established plant-wide optimization model,and the performance of plant-wide optimization for hydrometallurgy is described quantificationally,which provides a theoretical basis for the research on plant-wide optimization solution methods.3.Aiming to a large number of decision variables and constraints in the plant-wide optimization model which is difficult to be solved,an optimal method by the decomposition based on coupling relationship between manipulated variables is proposed.This method is to convert the plant-wide optimization problem into several easier solvable sub optimization problems based on the coupling degree between manipulated variables.The proposed method can improve the solution efficiency of the plant-wide optimization problem.Simulation experiments verify the efficiency of the optimization solution method.4.Aiming to the hierarchical decision-making problem of the procedure indices and the setting values of manipulated variables in actual production management,plant-wide hierarchical optimization method based on minimum consumption model is proposed.This method uses the minimum consumption model to describe the correlation between various technical indices,and then converts the plant-wide optimization problem into a two-level optimization problem,including the procedure-level optimization and the process-level optimization.Simulation experiments verify the efficiency of the above plant-wide optimization method.On this basis,aiming at the problems that there are numerous technical indices,and exists the coupling relationship among them when the hierarchical optimization method is used to solve the plant-wide problem for the large-scale hydrometallurgy problem,this dissertation presents a plant-wide hierarchical optimization method by decomposition based on the coupling relationship between technical indices.In this method,based on the coupling degree between technical indices,the procedure-level optimization problem is decomposed into several easier solvable sub-problems.Thus,the solution efficiency is improved effectively.Simulation experiments verify the efficiency of the plant-wide hierarchical optimization method by decomposition based on the coupling relationship between technical indices.5.Based on the theory studies,a plant-wide prediction and optimization system software for hydrometallurgy is designed and developed,and the theory method is realized.