Patent ID: 6187249
Filing Date: 2001-02-13
Classification: B27N

Abstract:
A process for forming a body of rice hulls, including: mixing rice hulls with a binder, the rice hulls being substantially whole untreated rice hulls with their edible rice grains removed, the rice hulls being processed to be of substantially uniform density by separating relatively dense particles and removing fines or dust particles prior to mixing with the binder, the binder comprising a composition whose setting requires or is accelerated by heat; forming the mixture of the rice hulls and binder into a formed shape of the body by placing the mixture in a mold at a forming station and closing the mold, the formed shape of the body including a water content throughout the formed body; raising the temperature substantially throughout the formed shape of the body in the mold until a parameter indicative of or associated with the start of setting of the binder reaches a predetermined level or is observed, the start of setting of the binder being defined by the formed shape of the body in the mold achieving a stable shape enabling opening of the mold and removal therefrom of the formed shape, the step of raising the temperature including application to the formed shape of an RF field of a suitable frequency and intensity to cause dielectric heating of water within the formed shape of the body, the parameter indicative of or associated with the start of setting of the binder comprising the appearance of condensing steam emerging from the body; removing the formed shape from the mold at the conclusion of the step of raising the temperature; and, in a separate and further step, curing the binder by progressing the setting of the binder in the formed shape beyond the start of setting by further treating the body in its stable shape under different process conditions than those from the step of raising the temperature, the step of progressing the setting of the binder including the step of discontinuing application of the RF field heating substantially immediately upon the appearance of the emerging condensing steam, to prevent burning or damaging the formed body from at least one of excessive heating and electrical arcing from the RF field.