Slurry collecting device and method for dismantling supporting beam

The invention discloses a slurry collecting device and method for dismantling a supporting beam. The slurry collecting device comprises a platform frame, a slurry barrel, a barrel frame, a drainage plate, a gathering plate, a water blocking plate and a supporting plate, the barrel frame is arranged on one side of the platform frame, the slurry barrel is arranged in the barrel frame, and the drainage plate, the gathering plate and the water blocking plate are arranged on the platform frame. The method comprises the following steps that S1, the cutting position of the supporting beam is confirmed; S2, a slurry collector is moved to a cutting opening to be put down; S3, the slurry collector is unfolded, and the height of the drainage plate is adjusted through the supporting plate; S4, cutting is started; S5, after the slurry barrel is filled with slurry, cutting is stopped, and then the slurry barrel is replaced; and S6, the slurry barrel is transferred to a designated slurry discharging position, and slurry is