OPTIMIZATION OF GOLD CLOSED-LOOP SUPPLY CHAIN PERFORMANCE WITH EMPHASIS ON SOCIAL RESPONSIBILITIES UNDER UNCERTAINTY (CASE STUDY: ZARSHOURAN GOLD

Mining supply chain management is important because successful chain implementation reduces costs, increases profits and productivity, and reduces risk. The extraction of these mines and the processing of mineral products, despite the positive effects on the economy and job creation, have many negative effects on the environment. The need to pay attention to the positive economic and social effects and adverse environmental effects of supply chains has led researchers to model social responsibilities. In fact, by modeling the supply chain and optimizing it, in addition to increasing the economic benefits of the supply chain, we can have a more accurate view of the potential decisions and future effects of these decisions. The purpose of this study is to mathematically model the supply chain of the Zarshuran gold mine with the aim of maximizing the economic benefits and social responsibilities simultaneously in the condition of uncertainty. Gold prices and customer demand are considered uncertain in the proposed model. This two-objective supply chain optimization model is one of the NP hard problems that cannot be solved by using precise methods. Therefore, meta-heuristic algorithms, Strength Pareto Evolutionary Algorithm II (SPEA-II), and Nondominated Sorting Genetic Algorithm (NSGA-II) are used here to optimize the supply chain. The results showed that there was an inverse relationship between supply chain economic profit and corporate social responsibility. It was also shown that with factors such as increasing production efficiency, both economic profits and social responsibilities of the company could be increased simultaneously. Sensitivity analysis of gold sales capacity showed that upon increasing sales, economic profits and social responsibility would increase. In fact, with the increase of production, the amount of greenhouse gas production and the amount of waste soil production as well as the amount of water consumption increase, but the welfare benefits divided by the region and the employment created overcome these negative factors and promote social responsibility.