Continuous production of expanded perlite for gypsum plaster using an updraft gasifier–cyclonic burner: Influence of burner temperature and feed particle size

• Continuous expanded perlite was produced with an updraft gasifier–cyclonic burner. • The best ASTM C35 density occurred at 1000°C. • The highest output occurred at 900°C with no agglomeration. • At 1000°C, <500 µm feedstocks passed ASTM C35 . • CO and particulate matter were acceptable, but NOx needs mitigation. This study demonstrates continuous production of expanded perlite for gypsum plaster using an integrated updraft gasifier–cyclonic burner system as a sustainable alternative to fossil-fuel heating. Burner temperature (900-1100°C) and feedstock particle size were evaluated for their effects on solids recovery, product morphology, ASTM C35 bulk density (96–192 kg m -3 ), mineralogy, and emissions. At 27.0 kg h -1 , 900°C gave the highest expanded-perlite yield (88.9% of feed) with no agglomeration, but produced an overall bulk density slightly below ASTM (91 kg m -3 ). At 1000°C, expanded-perlite yield decreased to 78.9% with minor agglomeration, while the overall bulk density met ASTM (143 kg m -3 ). At 1100°C, performance deteriorated severely, with usable yield dropping to 30.7% and agglomeration reaching 62.4% of collected solids. At 1000°C, feedstocks <500 µm satisfied ASTM C35 (143–179 kg m -3 ), whereas >500 µm exceeded the upper limit (290 kg m -3 ), indicating incomplete expansion under short flash residence time. X-ray diffraction under the recommended condition (1000°C, 250–500 µm) confirmed a predominantly glassy product (90.93 wt% amorphous; 3.07 wt% crystalline silica) with clay/mica and carbonates not detected. Particulate matter remained low and CO compliant at 900–1000°C, while nitrogen oxides require further mitigation.