Calibration of the cloud and aerosol spectrometer for coal dust composition and morphology

•Single-particle optical spectrometer measurements were calibrated for 0.5–50 μm coal dust.•Coal dust diameters were determined using light-scattering theories for irregular particles.•Coal dust was sufficiently de-agglomerated using a modified small scale powder disperser.•Particle size distributions were compared with cyclone-separated and sieve-segregated sizes.•Mass median diameters agreed with computer-controlled scanning electron microscopy measurements.