Foundries

The moulds used in foundries are often made on the basis of sand. One of the easiest mould making processes for foundries to use is the sodium silicate / CO₂ process. In this process, an appropriate sodium silicate is mixed with the sand. The mixture of sand and silicate is given an initial set by injecting CO₂ gas under pressure through the mould. The initial hardening is caused by a chemical reaction between the CO₂ gas and the sodium silicate. The alkali of the latter is partially neutralized, forming a silica gel which binds the sand particles together in a stiff mass. Later, as the mix loses moisture, further bond strength is provided. Another method for obtaining this partial neutralization and hardening of the sodium silicate is the use of organic esters, which are added in very small amounts.

In our well equipped mixing division we are able to prepare tailor-made sodium silicate foundry binders. Often certain organic materials, such as sugars, are mixed in the silicate to provide special properties.