Patent GB-736094-A (GB)
Title: Improvements in or relating to clay treatment
IPC: C09C1/42
Filed: 1952-10-29
Abstract: Kaolin in the form of a stack-like assembly of crystalline plates is reduced to a particle size such that all particles are less than 10 microns and at least 75 per cent by weight are less than 2 microns by forming a suspension of the kaolin in gaseous streams moving at near-sonic speeds and impinging such streams upon each other or on a target surface, separating the particles of at least 10 micron size from particles of less than 10 micron size and subjecting the larger particles to further impingements. The kaolin is thus reduced to individual plate-like components. The feed material is preferably freed from non-kaolin impurities and the impinging streams are preferably directed on to each other, employing air or superheated steam as carrier gas.  The treatment is suitably effected in a Blaw-Knox fluid energy pulverizer as described in Specifications 631,389 and 634,723, [both in Group II], which pulverizers incorporate a classification device adjusted to remove and return for further treatment particles of 10 micron size or more, and are provided with two air jets having a velocity approaching the speed of sound, spaced two inches apart and impinging upon each other.  A graph (not shown) compares the effect of employing air superheated to 720 DEG  to 840 DEG  F., and unsuperheated air, both being fed at 102-110 p.s.i.g.  If desired two or more Blaw-Knox mills may be employed in series, the large particles collected from the first mill being passed to a second mill for further treatment after which they may be added to p  the product from the first mill.ALSO:Kaolin in the form of a stack-like assembly of crystalline plates is reduced to a particle size such that all particles are less than 10 microns and at least 75 per cent by weight are less than 2 microns by forming a suspension of the kaolin in gaseous streams moving at nearsonic speeds and impinging such streams upon each other or on a target surface, separating the particles of at least 10 micron size from particles of less than 10 micron size and subjecting the larger particles to further impingements.  The kaolin is thus reduced to individual plate-like components.  The feed material is preferably freed from non-kaolin impurities and the impinging streams are preferably directed on to each other, employing air or superheated steam as carrier gas.  The treatment is suitably effected in a Blaw-Knox fluid energy pulverizer as described in Specifications 631,389 and 634,723 which pulverizers incorporate a classification device adjusted to remove and return for further treatment particles of 10 micron size or more, and are provided with two air jets having a velocity approaching the speed of sound spaced two inches apart and impinging upon each other.  A graph (not shown) compares the effect of employing air superheated to 720 DEG  to 840 DEG  F., and unsuperheated air, both being fed at 102-100 p.s.i.g.  If desired, two or more Blaw-Know mills may be employed in series, the large particles collected from the first mill being passed to a second mill for further treatment after which they may be added to the product from the first mill.