Patent ID: 7524386
Filing Date: 2009-04-28
Classification: B01F,B28B,B28C,C04B,Y02W

Abstract:
1. A method for preparing lightweight cement composite slurry which can be supplied in a continuous curtain for uniformly covering a thick layer of fiber in the production of a reinforced structural cement panel comprising: feeding a dry cementitious powder comprising cement, gypsum and aggregate from a bin into a horizontal powder mixer having a horizontally mounted screw auger; discharging the dry cementitious powder mixture from the screw auger into a horizontal pre-mixer equipped with a paddle rotated about a central horizontal axis by the screw auger; feeding a liquid stream comprising water, into the horizontal pre-mixer through an inlet; mixing the cementitious powder and liquid to form a wet powder slurry mixture; dropping the pre-mixed powder and liquid mixture from the upper portion of a vertically oriented mixing chamber to a lower portion of the vertically oriented mixing chamber equipped with a paddle mixer rotated about a vertical shaft by a top mounted motor; mixing the water and powder in the lower portion of the vertically oriented mixing chamber; and pumping the slurry to a slurry headbox for depositing the slurry as a continuous curtain on a thick fiber layer on a web in a panel production line, wherein the powder and liquid are mixed for an average mixing residence time in the mixing chamber lower portion of about 10 to about 360 seconds while a spinning paddle applies shear force to the slurry in the mixing chamber to mix the powder and water to produce a uniform slurry of a lightweight cement composite that has a consistency that will allow the slurry to uniformly cover a thick layer of fiber on a web to produce a fiber reinforced structural cement panel.