Sodium orthosilicate → Silicic acid (H2SiO3), disodium salt, pentahydrate

Participants

Reaction Conditions

Reaction Steps

A sodium metasilicate pentahydrate liquor was prepared by blending a sodium silicate solution with an SiO2 /Na2O ratio of 3.22 with caustic solution. The mole ratio of Na2O: O:SiO2 :H2O of the liquor was 0.99:1.00:4.97 and the liquor was maintained at 75°C to prevent any crystallization until the test was started. The liquor (97.5 pbw) was cooled to 70°C and 2.5 pbw of seed particles were added. The seed was less than 200 mesh and had a composition similar to the liquor. The temperature of the liquor fell until the crystallization began. The crystallization began after about 45 minutes and continued for about 60 minutes until the cake was hard to the touch. Evolution of heat of crystallization continued for about 30 minutes more. The cake was allowed to equilibrate for 60 minutes and then ground in a jaw crusher. The total processing time prior to crushing was 3 hours and 15 minutes. The cake and resulting material had to be passed through the jaw crusher 6 times before all of the material was reduced to below 20 mesh. In the process a large percentage of fines were produced and the product was dusty. The product contained about 1.5% iron.

Provenance & Evidence