Production Costs Calculation Model in Crushing and Screening: Using a technical-economic approach tool for finding the optimal production costs when comparing technical and economical solutions

The mining and quarrying industries represent a highly important sector of the Swedish economy. The mining industry operates globally, whereas the quarrying industry operates on a regional/local basis. Demands for metal and construction aggregates have increased over the last decade, and almost 80 billion tons of solid minerals and rocks are extracted from the earth’s crust each year. Construction aggregates are the largest part of this extraction. Most of the metals in the crust are in mineral form, with one or more elements in chemical compounds. To extract the metals, one must first reduce the rock to fine or very fine particles, so creating the right properties for mineral beneficiation and metal extraction.

Construction aggregates are used as ballast in concrete and in asphalt or by itself in road building and other infrastructure, such as dams, protection, filling, and landscaping. Construction aggregate ranges in sizes from large boulders to very fine sand, but normally the construction aggregate sizes are in the range of 1–100 mm. Where the railway aggregates are in the coarser part of this range, the aggregates used for asphalt and concrete in the middle part, and the sand in the finer part.

Crushing and screening are among the common size reducers and size sorters in the mining and quarrying industries. The crushers are machines for breaking rocks or other minerals into smaller particles/fragments. The screens are the size-sorting machines for separating coarser particles from finer particles. Technical process simulation and equipment selection for crushing and screening (C&S) plants are well established today for mining and quarrying plants.

In this dissertation I develop a product cost calculation model (PCCM) that adds one more dimension to the area of process simulation, providing guidelines for calculating product costs within C&S plants and finding the process alternative with the lowest product cost for a C&S plant process application.

The PCCM calculates the product costs using process uptime costs, process downtime costs, salary costs and auxiliary costs. The process uptime and downtime costs include capital costs and dynamic process costs such as wear parts, spares, tools, and power consumption.