An empirical size‑distribution function used to describe and fit the particle size distribution resulting from blasting, representing the cumulative (or differential) frequency of fragment sizes with parameters that control characteristic size and tail behaviour. It is applied to estimate post‑blast fragmentation for blasting design, crushing throughput and handling predictions, recognising that it is an empirical fit rather than a mechanistic fracture growth law.

Principle

The Swebrec function provides a flexible parametric form that captures both a modal characteristic size and an asymptotic tail for fines and coarse fractions; parameters are estimated from measured size distributions and then used to interpolate or extrapolate fragmentation outcomes for similar conditions.

Demonstration

Illustrative scenario: after a primary blast in a bench, sieve or image‑analysis measurements of fragment sizes are fitted to the Swebrec curve to estimate the fraction passing crusher feed size; the fitted parameters are then used to evaluate alternative blast energy distributions to increase the proportion of undersize material.

Misapplication

Applying Swebrec parameter values obtained from one lithology, blast pattern or scale to a different rock type, explosive type, or bench geometry without site validation; the error is treating empirical parameters as universally transferable rather than context‑dependent fit coefficients.

Consequence

When validated locally, Swebrec supports operational decisions—blasting design, crusher selection, and productivity estimates; when misused, it leads to incorrect predictions of crusher throughput, increased handling cost, safety risks from unexpected oversize, and suboptimal blast design.

Reversal

Swebrec’s empirical form may fail for multimodal distributions produced by mixed lithologies, extensive secondary breakage during handling, or when fragment shape (not just size) controls downstream behaviour; in such cases multi‑modal or mechanistic models may be required.

Boundary

Clearly within: primary post‑blast fragment size distributions from a relatively uniform rock mass where sufficient sample data exist to fit parameters. Boundary case: blasting near contacts of two rock types producing quasi‑bimodal output—fit possible but parameter interpretation ambiguous. Clearly outside: progressive fragmentation during crushing and screening, or fragment shape distributions where a size‑only fit is insufficient.

Semantic Tension

Empirical statistical fitting (Swebrec) ↔ Mechanistic fragmentation models: Swebrec offers a compact descriptive tool for operational prediction, while mechanistic models attempt to derive fragment size from physical fracture and explosive energy mechanics; the two approaches constrain each other in calibration and interpretation.

Synthesis

Swebrec is a practical empirical descriptor of blast fragmentation that efficiently summarises size distributions for operational use, but its predictive reliability depends on representative sampling, awareness of lithologic and scale changes, and validation against the actual blasting and handling context.