A heuristic approach to long-range production planning of cement quarry operations

Abstract

Cement manufacturing requires sustained supply of raw materials from limestone quarry. Raw materials inventory in limestone quarry is identified as a block model, usually, consisting of thousands of blocks. Each block consists of a distinct amount of chemical constituents which are vital for cement production. An individual block never satisfies the process quality constraints; therefore, the blending of various quarry blocks with expensive additives purchased from the market becomes a prerequisite. The objective of a quarry production scheduling model is to mine available blocks in a sequence such that cement plant quantity and quality requirements are satisfied. Achieving a solution to the problem, where each block is defined as an integer (0-1) variable, often within reasonable time, has been a challenge for the mining industry. In this article, the complex production scheduling problem is divided into two sub-problems, where quarry sequencing algorithm develops feasible quarry plans and mixed integer linear programming based blending formulation minimises cost by selecting a plan that requires least amount of additives from the market. The implementation of methodology on an existing operation ensures time as well as cost savings compared to the schedules produced manually.

Keywords:

• production scheduling
• mixed integer linear programming
• raw materials blending
• cement/mining industry