A common and major issue encountered in large mining operations is the presence of excessive slabs in the primary crushing station product. This problem is especially prevalent in the iron ore mining utilising large jaw crushers as the first stage of crushing. Due to the nature of jaw crusher operation, combined with large feed opening dimensions and large closed-side-settings, particles with one dimension up to 600 mm can frequently be observed on the primary crusher product conveyor. Mining sites experience equipment damage, belt rips, transfer chute blockages and/or silo/bin obstructions. These events significantly impact operations, as they often result in prolonged stoppages for repairs and material clearing. Additionally, some of these interventions may expose personnel to unsafe working conditions, such as working at height or in confined space. A relatively straightforward solution is to implement a secondary crushing stage directly after the primary jaw crusher station. In recent case studies, a cone crusher has been used to reduce the oversize and slabby particles down to a size and shape suitable for transport. However, in most cases the available footprint to install a secondary building is limited, and the expected plant shutdown make project feasibility difficult to justify. This paper describes a case study at a large iron ore plant in Brazil where three secondary crushing circuits were successfully implemented using a modular design with agile assembly and reduced foundation infrastructure costs. The total installation time frame, considering all mechanical and electrical activities, was 56 days – effectively 28 per cent shorter downtime than the original project schedule – and immediately mitigated the unplanned downtime and maintenance work that the oversize slabs caused on the downstream equipment.