Abstract: A filter leaf includes a continuous, elongated closure member, a first screen welded around its entire periphery to one side of the member, and a second screen welded around its entire periphery to the other side of the member to define a filtrate collection space between the two screens and the member. Means are provided for removing filtrate from the collection space. The filter leaf is made by clamping the closure member and one of the screens between two plates so the screen covers one side of the member and so the outer portions of the member and screen project outwardly from one of the plates. The outwardly projecting portions of the screen and member are irradiated with a laser beam to melt the screen and member to cause them to fuse together. The periphery of the outwardly projecting portions of the member and screen are moved relative to the laser beam while the member and screen are clamped together to form a continuous weld of the screen to the member around the entire periphery of the screen.

Abstract: Filtering apparatus includes a shell with at least one filter leaf mounted in the shell to be rotatable about an axis. Means are provided for forcing a solid-containing liquid into the shell and into the leaf to form a cake of solids on the leaf. Means are also provided for removing filtered liquid from the leaf and the shell. A nozzle in the shell is disposed adjacent the leaf to direct a jet of sluicing liquid against the leaf as the leaf rotates. A sluicing liquid is supplied to the nozzle to wash solids from the leaf, and means are provided for moving the nozzle toward and away from the axis of leaf rotation in a plane substantially parallel to the leaf to remove solids from the leaf.