A linear programming model to minimizing Tonage-distance of raw materials and final products shipment in Iran's decorative stone industry chain

Basically, in the chain of the decorative stone industry, the cost of transporting the excavated rock from mine to the rock cutting factories, and then shipping of the processed plate and slab stone to the market places has a major impact on the finished product price. In this research, firstly, each of the decorative stone chain components including mines, rock cutting factories and consumer markets in Iran was divided into 10 main poles. Then, the linear programming model for minimization of total transporting tonnage and distances of raw rock from poles to processing poles and processed slab from mine to trade materials and transferring processed rocks from factories to market poles were defined. The constraints of the model were defined based on the proportion of production capacities in poles throughout the production chain. After solving the model with the GAMS software, the optimal delivery tonnage between the poles as scenario 1 was calculated. Also, two separate scenarios have been defined in terms of 20 percent increase in production capacity of mine poles and 20 percent increase in consumption and processing capacity poles. The second scenario reduces the average shipments per unit product by 3.9 %, but it has no positive impact on the utilization ratio of the production capacity in mine and factory poles. The third scenario improves the utilization rate of the mines poles, however increases the total shipment of the raw material from the mine to the factory by 28%, and also increases the average distance per unit product along the chain by 8.2%. This scenario could lead to increasing the unit production cost and reducing the competitiveness of the final product.