七○砂即石灰石砂,由于粘结剂的不同,目前有水玻璃七○砂和自硬七○砂。自硬砂中又有水泥自硬砂、粘土干模自硬砂等,本文介绍的就是其中之一。粘土干模自硬砂虽然操作比较麻烦、效率低,但是高锰钢铸件目前仍主要是采用这种方法,特别是对缺乏水玻璃和二氧化碳资源的单位十分适用,故本刊在此刊登,以供参考。 Seventy sand or limestone sand, due to different binders, currently has seventy grains of water glass and seventy grains of self-hardened sand. In the self-hardening sand, there are cement self-hardening sand, clay dry mold self-hardening sand, etc. This article describes one of them. Although the dry sand mold self-hardening sand is difficult to operate and low in efficiency, high-manganese steel castings are still mainly used this method, especially for units lacking water glass and carbon dioxide resources, so the publication is published here. for reference.