A method for separating fluid from a mixture of fluid and fibrous lost circulation material, the method including introducing the mixture onto a screen assembly that is vibrating for passage of the fluid through the screen assembly and for separation of fibrous lost circulation material from the fluid, the screen assembly comprising a plurality of screens one on top of the other and including at least a first screen and a second screen, one of the screens with comprising a screen mesh woven with non-square openings as viewed from above.