An improved apparatus for on-line coal flow control in vertical spindle mills comprising a plurality of independently adjustable flow control elements and positioning rods that adjust the positioning of those flow control elements. Each flow control element is positioned within the discharge turret of the vertical spindle mill along the outer wall of the discharge turret proximate the entrance to its corresponding coal outlet pipe. The adjustable rods are seated on the side of the discharge turret of the coal pulverizer and are connected to the flow control element horizontally. The flow control elements can be independently rotated by +/−90 degrees about the positioning rod axis, and can also be moved back and forth in the horizontal plane. Therefore, each flow control element has two degrees-of-freedom: rotational and linear displacements. The apparatus improves boiler performance by making it possible to operate the boiler with reduced pollutant levels (e.g. NOx, CO) and increased combustion efficiency.