Real-time Optimization Of Hydrometallurgy Cementation Process

As the rapid development of metallurgical industry, making full use of low-grade nonferrous metal resources has become more and more important to the strategy of sustainable development in China. As one of the two extraction technologies of smelting, hydrometallurgy has the advantages on high percentage of recovery of valued metals, protection of the environment and achievement of the continuity and automation in the production process. Therefore hydrometallurgy is more suitable for recovering low-grade metal resources. Cementation process is an important procedure of gold hydrometallurgy. The control of cementation production process is stay in the level of off-line analysis, experience adjustments and manual control now in China. These result in low productivity, high consumption and instability of product quality in the vast majority of gold hydrometallurgy enterprises, which restrict the development of China’s gold hydrometallurgy industry.This thesis aims at the optimization of the quality of products in cementation process of hydrometallurgy. Based on deeply analyzing the production process and characteristics of cementation production process, it is researched comprehensively and systematically on the modeling and optimization of the cementation process of hydrometallurgy. The main researches are summarized as follows:1. Through analyzing the basic principle of cementation process, the major factors affecting the cementation process were briefly analyzed firstly. Based on the principle of reaction kinetics and relationship of material balance, the dynamic first principle model of cementation process was established. By model simulation, the dynamic and steady state features of the cementation process were revealed. The secondary variables of the data modeling were identified. And the foundation of data modeling was established. To aim at the difficulty of obtaining accurately the parameters of the dynamic first principle model and the influences of some assumptions on the accuracy of the model, the data models of cementation process were established using the Kernel Partial Least Square algorithm. By simulation experiment, the efficiency of the data modeling method was verified.2. Aim at the repetition nature of cementation process, the batch-to-batch iterative optimization method was used in the optimization of cementation process, and the optimal input trajectory of zinc powder flow rate was obtained by optimizing the nominal model. Due to the uncertainty in the production process, model-plant mismatches need to be considered. To solve this problem, the modifier adaptation method was used in the batch-to-batch iterative optimization of cementation process. The optimization objectives and constraint conditions are real-timely corrected to correct Karush-Kuhn-Tucker conditions using the information of previous batch runs as well as the measurement information in the present, and the actual optimal control trajectory of cementation process is achieved. The results of simulation experiment verified its efficiency.3. Aim at the real-time optimization of cementation process, and the impacts of the unmeasured disturbances and model-plant mismatches of batch-to-batch and within batch in process optimization. The adaptive real-time optimization approach of integrated batch-to-batch and within batch optimization approach was proposed. On the one hand, the integrated optimization strategy can combine the advantages of both methods to overcome the unmeasured disturbances of batch-to-batch and within batch. On the other hand, the modifier adaptation method can overcome effectively the model-plant mismatches of batch-to-batch and within batch. By simulation experiment, the efficiency of the real-time optimization approach was verified.4. By combining the proposed modelling and optimization methods, the operating system software for the prediction and optimization of cementation process was designed and developed, and the optimal operating guide for cementation process was provided.