Evaluating the deposit layer and ring formation during coal-ash-based lightweight aggregates sintering

Sintering with a rotary furnace is efficient for ceramic manufacturing but faces challenges like deposit buildup and ring formation, which can disrupt production. Deposits adhere to the furnace's inner pipe surface, hindering material flow while ring formation creates ring-shaped obstructions. This study investigated these issues during waste coal-ash-based lightweight aggregate (WCA-LWA) sintering, examining factors like particle size, material proportioning, and sintering parameters. Findings indicate that particles ≤300 μm contribute to ring formation. Applying a 20 wt% coating reduces ring formation. SEM-EDS revealed Na traces in the deposit layer indicating coating and fine pellets (≤ 50 μm) contribute to deposits. Rietveld XRD assessed crystalline and amorphous phases of raw WCA, sintered WCA-LWA, and deposit materials. Adjusting input feed parameters helps reduce ring formation, with a feeding rate of 15 g/314 s enhancing WCA-LWA production by 15.5 % before ring formation appears. While adjusting sintering parameters may not eliminate ring formation, it reduces its occurrence, minimizing the need for physical intervention, costly cleaning, or unplanned furnace shutdowns. • Investigated deposit layer and ring formation during WCA-LWA sintering in rotary furnace. • Identified particles ≤300 μm and coating/fine pellets ≤50 μm as key contributors. • 20 wt% coating optimized to reduce ring formation and pellet agglomeration. • SEM-EDS and XRD revealed deposit growth mechanisms and phase transformations. • Adjusted feed mass (15 g/314 s) improved production by 15.5 % before ring onset shutdowns.