Natural gypsum mined from the ground reaches the wallboard plant and is stored in a rock pile until needed. The rock is blended on the rock pile by a bulldozer and pushed into a pit. From there it's fed into a pan feeder. The pan feeder uniformly takes the natural gypsum rock onto a conveyor belt, which carries it to a crusher. The crusher is a huge swing hammer mill that breaks up rocks larger than two inches in diameter while allowing smaller rocks to pass through it. The crushed rock blend is conveyed to silos that take the crushed rock directly to the rock dryer.
The rock dryer is a large rotating oven that evaporates any surface moisture on the rock. The dry gypsum is then ground in a roller-type crushing mill. These powerful machines grind the gypsum into a fine powder called "land plaster."
The land plaster is "calcined," or heated to remove three-quarters of the water chemically bound in gypsum. The result is stucco, a very dry powder that, when mixed with water, quickly rehydrates and "sets up". The stucco is fed into large stucco storage silos to await use in the wallboard manufacturing process.
The pin mixer is the first step of the "wet end" manufacturing process. The stucco is blended with water and other ingredients depending on the type of wallboard being made to make a "slurry," or paste. The slurry is spread on a moving stream of cream-coloured paper and then covered, or sandwiched, with the top paper to be formed into wallboard at the forming station.
The long sheet of wallboard then is set aside to allow the slurry time to dry. After it has dryed it is sent to the knife. There it's cut into specified lengths. The cut wallboard panels are turned and placed in the kiln to dry.
Once it leaves the kiln at the "dry end" of the process, the wallboard is sent to a bundler where it is trimmed to the exact length, taped in two-panel bundles, stacked and moved to the warehouse to await shipment to customers.