Abstract: A powder handling system includes chambers for collecting mixing and loading of powder, with the collecting and loading chambers being so arranged as to empty into the mixing chamber. The collecting chamber is vacuumized, and is in valved, gas-flow communication with the loading chamber, to enable the establishment of a negative pressure in the latter during operation. This permits the introduction of a fresh charge of powder without the need to shut down the system. A vertical partition is provided to divide the mixing chamber into two compartments; by discharging powder from the collecting and loading chamber into different compartments, and by thereafter mixing the two streams, blend consistency may be ensured.