Foundry Sand Reclamation Technology And Applications

In our country, more than ten millions used foundry sand is dumped into the nature every year. The great dumping of used sand is not only a great waste of resource, but also pollutant to environment. Reusing reclaimed sand has become a question that need to be resolved urgently in casting industry.In this paper, different reclaiming technologies of used mixed sand and used sodium-silicate bounded sand are studied, and then reclaimed sand is used to make cores or moulds to test its usability. The purpose is to reduce the dumping of used sand by way of using reclaimed sand to make moulds or cores, totally or partly.The experimental results of used mixed sand indicate that reclaimed sand, which is produced by way of dry reclamation and low thermal + dry reclamation, can be only used to make moulds. The selective reclamation is that used resin bonded sand is divided from used mixed sand, and then used resin bonded sand is reclaimed. Through dry reclamation and thermal + dry reclamation, the quality of reclaimed sand is greatly increased. Thermal reclamation comprises of low and high temperature. Compared with low thermal reclamation, the quality of reclaimed sand is increased a little by way of high thermal reclamation. From the point of economy, low thermal reclamation is preferred .The technological experiment of reclaimed resin bounded sand produced through dry reclamation is made, the way of which is standard. The results indicate that reclaimed sand can be only used partly to make cores. Because of the changes of reclaimed sand s quality, the technology of making cores must be adopted, the specific value of resin and hardener is below the standard value, 4. When 30% reclaimed sand, 2.5%(sand weight) resin, 0.7%(sand weight) hardener are added to * make cores, at this time the specific value of resin and hardener is 3.57, the quality of cores can meet the demand of production.The technological experiment of reclaimed resin bounded sand produced through low thermal + dry reclamation is made, and the results indicate that reclaimed sand can be only used partly to make cores too. When 5% reclaimed sandis added to make cores, the quality of cores is up to standard; When 30% reclaimedsand, 2.2%(sand weight) resin, 0.7%(sand weight) hardener are added to make cores, at this time the specific value of resin and hardener is 3.14, the quality of cores can meet the demand of production.The experimental results of used sodium-silicate bounded sand indicate that the two ways, which are dry reclamation and low thermal + dry reclamation,can all produce eligible sand. The latter is better than the former in quality, but worse in economy.From the point of economy, reclaimed sand which is made by way of dry reclamation is used to make moulds and cast.At present, sand reclamation may not be lucrative, but this is the direction of development, and is a link of green casting.