Abstract: An adjustable, diffusing coal valve for use in controlling flow of air and pulverized fuel to a burner is disclosed. An exemplary embodiment comprises a conduit section having an inner cross-sectional area and a diffusing damper plate mounted to said conduit section and rotatable within the conduit section between an open position and a closed position. The diffusing damper plate has a periphery dimensioned to occupy a majority, but less than all, of said inner cross-sectional area when in the closed position, and includes a plurality of perforations distributed within an outer region of the plate, thus allowing coal particles to flow through the damper plate when it is in a closed or partly-closed position.