A baghouse is a gigantic industrial vacuum cleaner.
Many manufacturing and power generation processes create huge amounts of dust, especially in burning, grinding, or cutting applications. To prevent it from winding up all over the factory, not to mention in the employees' eyes and lungs, this dust must be collected in a controlled manner. To this end, large vacuum fans create suction to pull the dust through a duct of some kind (sometimes rubber lined for durability, dust can be very abrasive) and into the baghouse. These ducts end in dust hoods covering the process that is generating the dust. The process is very much like a central vacuum system on a huge scale.
As in a standard household vacuum cleaner, the vacuum fans pull the dust into a bag that filters the clean air from the dust, allowing the air to escape through the mesh of the bag but trapping the dust in the bag. While a household vacuum cleaner bag is less than a foot tall and a few inches in diameter, industrial baghouse bags can be any size from five feet tall and a foot in diameter to the size of a living room, depending on how much dust the process generates. Furthermore, the baghouse does not collect the dust in the bag. Instead the bags act as filters which allow clean air to pass but traps the dust inside a large bin the bags are in.
Some dusts are more troublesome than others, and can stick to the side of the baghouse bag instead of falling to the bottom. When this happens it can clog the mesh and prevent clean air from escaping, which reduces the vacuum pressure in the dust reclaim system, reducing its effectiveness. The most common solutions to this problem are the baghouse popper and the baghouse vibrator. The popper shoots bursts of compressed air at regular intervals against the side of the bag to shake loose the dust, while the vibrator shakes the bag continuously to keep dust form sticking to the side of the bag.
Once collected in the bag, several things can happen to the dust. In some cases it is useless waste and must be sent to the landfill for disposal. Other dusts can be recycled, either back into the process that generated the dust in the first place or into other products. Fly ash from coal power plants, for example, can be recycled as an inexpensive additive for cement and concrete.