用石炭石砂代替石英砂,是铸造用砂的一次重大变革,它具有可以就地取材,降低成本,符合战备要求,提高铸件质量,消除矽尘、、改善劳动条件等优点。戚墅堰机车车辆工厂自1970年试验成功石炭石砂(又名七O砂)以来,先后又对这种新型用砂进行了两次变革。第一次变革是在七O砂中加入一种硅酸钙的混合凝 The use of carbonaceous sand instead of quartz sand, casting sand is a major change, it has the availability of materials, reduce costs, meet combat readiness requirements, improve casting quality, eliminate silica dust, improve working conditions and so on. Qishuyan rolling stock factory since 1970, the successful trial of carbonated sand (also known as the seven O sand), has this new type of sand has undergone two changes. The first change was the addition of a mixed calcium silicate gel to the Seosao sand