Application of Life Cycle Assessment to Multi‑Product Aggregate and Mineral Production System

Licentiate thesis, 2026

Rock material is one of the most extracted resources in modern society after water. Rock material is extracted and processed into products such as aggregates and minerals needed for modern infrastructure development, including roads, bridges, railways, and other industrial applications. Since the production of these products consumes resources (material and energy) and generates waste (both hazardous and non-hazardous), it results in the emission of pollutants into the air, water, and soil, thereby affecting the environment. This poses a requirement to investigate the product-specific environmental impacts for aggregates and minerals.

Life Cycle Assessment (LCA) is a product-level environmental assessment method widely used to estimate the environmental impacts of product fractions produced by aggregates and mineral production systems, owing to its quantitative nature and the broad range of impacts it covers. However, LCA has limitations due to its comprehensiveness, which leads to simplifications to represent large, complex, and dynamic systems. Aggregates and minerals production systems are inherently complex due to changes in production and resource consumption, which are influenced by changes in processing circuit configuration, rock properties, periodic maintenance activities, machine wear, and other site-specific characteristics.

The processing circuit configuration used in the aggregates and minerals production system produces multiple product fractions. To understand the influence of circuit configuration on environmental impacts, it is important to estimate the impacts of each product fraction. In this research, case studies have been developed based on aggregate and mineral production sites. Within each case study, LCA, process simulation, and site-specific data have been used to investigate the influence of circuit configuration on product fraction-specific environmental impacts.

The results indicate that the product fraction-specific environmental impacts are influenced by the circuit configuration. This is because of the number of processing machines (e.g., crushers and screens) the product fraction passes through. The energy requirement cumulates as each product fraction passes through different machines, giving a distinct energy signature per tonne of each fraction. The result further shows that reconfiguring the circuit to produce multiple product fractions rather than a single product fraction leads to lower impacts. This is due to the allocation of consumables and waste among the multiple product fractions. In addition to the influence of circuit configuration on the environmental impacts, the research also investigated the influence of expanding the circuit to valorize waste rock material. Circuit expansion leads to higher overall environmental impacts but also to potential increases in revenue and the recovery of valuable product fractions, and reduces waste generation.