The treatment process of the test device is as follows: (1) In the hot metal treatment site with slag plate slag, the high temperature slag is transported to the cooling plant by railway; ② Lift the slag tray with a crane and tilt it into the primary cooling slag pit; (3) Use heavy machinery to cool the slag in the slag pit evenly, remove the large metal, and prepare to load the slag into the hopper; The slag is loaded into the hopper with heavy machine, and the slag is screened by the vibrating screen on the hopper. The slag under the screen falls into the hopper, and the slag on the screen is poured into the pit. The slag in the hopper is added into the rotary cooler through the feeder, and removed after rotating and cooling at a certain speed. ⑤ After about 30 minutes of treatment in the rotary cooler, the slag removed can be cooled to below 100℃; ⑥ After cooling, the slag is transported to the product pit by conveyor belt; ⑦ Sampling of the slag stored in the pits, transported by the air compression pipeline to the analysis center for slag composition confirmation, in the confirmation of its environmental safety, slag transported to the aging yard.