Device and method for cleaning and recycling float coal behind top coal caving support

The invention provides a device and method for cleaning and recycling float coal behind a top coal caving support. The device is based on a rear support connecting rod of the top coal caving hydraulic support and comprises an overturning plate, a telescopic plate, a telescopic oil cylinder and a first overturning oil cylinder; a connecting column and a hinge seat are arranged on the front side surface of the overturning plate; the connecting column is hinged to the inner side face of one rear support connecting rod, and a notch allowing the overturning plate to rotate around the same rear support connecting rod is formed in the section, close to the connecting column, of the overturning plate; a sliding groove extending in the length direction of the overturning plate is formed in the overturning plate; the telescopic plate is matched with the sliding groove; a cylinder body of the telescopic oil cylinder is fixed to the overturning plate, and a cylinder head is hinged with the telescopic plate; and a cylinde