Abstract: A slide valve for use in throttling solids flow, preferably including a pair of opposed discs. The valve discs are in bearing contact with the valve seat and effectively will operate with the valve in almost any position. The internal valve construction and arrangement is unitized which simplifies removal of the internals as a single assembly, and permits quick reassembly as well as adjustment. The discs are retained by guide bars to insure that disc movement is essentially limited to a back and forth motion. The valve discs according to the invention can be centered in the valve so that the discharge is centered in the conduit in which they are mounted, thereby reducing flow impingement on the conduit wall to avoid or minimize erosion, or they can be operated singly and/or independently or in conjunction with each other in order to provide desired flow control. With single disc operation, one disc may be retracted and control achieved by throttling with the other disc against part of the seat.