A new Mobile Half-Frame Bulk Bag Unloader with multi-purpose hopper allows material to be discharged from bulk bags, manually dumped from sacks and conveyed to downstream processes and storage vessels dust free. For in-plant mobility, the system minimizes weight and achieves a low center of gravity by eliminating upper frame components, relying instead on the user''s forklift or plant hoist to suspend the bag above the unit during operation. The bulk-bag-to-hopper interface consists of a SPOUT-LOCK® clamp ring positioned atop a pneumatically actuated TELE-TUBE® telescoping tube, allowing dust-tight connections and unrestricted flow between the bag spout and hopper, as well as automatic tensioning of the bag as it empties to promote flow and evacuation. The telescoping tube raises the clamp ring assembly that seals the clean side of the bag spout to the clean side of the telescoping tube, and then lowers until the bag spout is pulled taut. Once the spout is untied, the telescoping assembly exerts continual downward tension on the spout, elongating the bag as it empties.