When the temperature is heated to 400~600 ℃, there is an obvious exothermic peak, indicating that at this time, most of the residual resins absorb heat, reach the critical energy when the surface resin film is damaged, and begin to burn. The intermediate products generated are oxidized into CO and CO2 with the further reaction, and other gases are released, making the quality of used sand reduce again. When the temperature reaches 700 ℃, the quality tends to be stable, and it can be considered that the residual resin has been completely decomposed and burned, and the regeneration process is basically completed.
Practical application of Resin-coated Ceramic Foundry Sand thermal regeneration
The thermal regeneration process obtained from the experiment was applied to the old sand regeneration process of Ceramic foundry coated sand in a factory. After three times of use, the sand regeneration effect was better and the surface quality was significantly improved. The shell casting made of Ceramic foundry coated sand recycled sand had higher surface finish, without defects such as porosity and sand sticking. It shows that the thermal regeneration process has good application value.
Conclusion of reclamation process of Resin-coated Ceramic Foundry Sand
1) The thermal regeneration process parameters of 100 ~ 200 mesh Resin-coated Ceramic Foundry Sand are as follows: the heating temperature is about 700℃, and the holding time is 20 min.
(2) The tensile strength and flexural strength of Ceramic foundry coated sand prepared from recycled sand reached 2.63 MPa and 6.08 MPa, respectively, and the gas evolution was reduced by 0.40 mL/g. The process performance was basically similar to that of new sand coated sand.
(3) After thermal regeneration, the molecular bonds of the resin film on the surface of Ceramic foundry coated sand were destroyed. The intermediate products were continuously oxidized, producing gases such as CO and CO2. Some inorganic substances were decomposed, and the sand particles regained high surface energy.
Sanmenxia Qiangxin Foundry Material Co., Ltd. Focuses on The Reclamation Career
Fused Resin-Coated Ceramic Sand recycling is a green environmental protection project that our company focuses on promoting for high-end alloy steel casting production. With the increasingly prominent contradiction between China's economic and social development and resource and environmental constraints, the recycling of waste sand has become an important problem that must be solved by foundry enterprises. Our company has increased investment in scientific research and solved the problem of waste sand recycling, so that the reclamation rate of waste sand has surpassed 95%, and achieved social benefits and enterprise benefits jointly improved. At the same time, cleaner production and zero discharge of solid wastes would effectively protect the health of workers at the site.