Patent ID: 7918950
Filing Date: 2011-04-05
Classification: C04B,Y02W

Abstract:
1. A method of making a gypsum fiberboard panel comprising: providing an aqueous slurry comprising gypsum and a first portion of cellulose fibers to a reactor, reacting the gypsum and a first portion of cellulose fiber in the reactor to produce a calcined crystalline gypsum and cellulose fiber slurry, uniformly reinforcing the calcined crystalline gypsum and cellulose fiber slurry with a second portion of cellulose fiber after the reacting step to form a second slurry, depositing the second slurry to form a mat, dewatering the mat, rehydrating the mat to form a gypsum cellulose fiber mat, and then drying, cutting and finishing the mat into a final gypsum fiberboard panel, wherein no more than one half of the total cellulose fiber in the final gypsum fiberboard panel is added in the first portion to the reactor for calcination with the gypsum and wherein the amount of steam energy used in the reactor to calcine the gypsum and fiber is about 40% to 50% less than when all of the total cellulose fiber is added in the first portion to the reactor, and wherein the amount of unhydrated hemihydrate in the final gypsum fiberboard panel is reduced by more than 50% from the level of unhydrated hemihydrate in a panel made with a slurry with all of the cellulose fiber calcined with the gypsum.