A dust and particulate containment system for an open sided gallery conveyor, having a movable curtain for covering the open side of the conveyor and a trough positioned within and extending along a length of the conveyor. A rail is arranged within the conveyor and a carriage, having an opening for transferring bulk materials therethrough via a sealed connection to a cross conveyor, is positioned to move along this rail. Sealing strips in the trough retain the curtain tautly in place and seal the open side of the conveyor. As each carriage moves along the rail, a spreader frame attached to the carriage biasingly opens the sealing strips, and temporarily frees the curtain from being retained, so that the freed curtain is lifted over the carriage to avoid covering the opening in the carriage, so that transfer of bulk materials in the conveyor can occur through the opening.