|
Because the physical properties of silicates vary so widely, PQ makes available many different types of products. Among them are lump and powdered glass, liquid silicates, hydrous silicates, metasilicates, and potassium silicates. The raw materials needed to produce soluble silicates are silica sand, soda ash (potash), and water.
Alkali is determined using pH value or total titratable alkali content. This simple acid/base titration uses a colored mixed indicator. With pH controlled endpoints, autotitrators eliminate operator error.
A Gravimetric or Volumetric silica test can be used to determine silica concentrations. Atomic absorption spectroscopy is another method for determining silica concentrations. All three techniques require experienced, highly trained operators. An automated computer program based on proprietary Geriche charts can also be used.
Total solids is the sum of the silica and the alkali. PQ supplies a variety of solids products at equivalent ratios to meet the diverse needs of our customers.
Weight ratio is the most important silicate variable. Ratio determines the product’s solubility, reactivity and physical properties. Ratio is either the weight or molar proportion of silica to alkali.
Density is an expression of total solids and is typically determined using a hydrometer. As temperatures increase, density decreases. When solids content increases, density increases.
pH is a function of silicate composition and solids concentration. The pH value of silicates does not truly reflect the alkali content of solution, due to the strong buffering capability of silica. This means the pH of a silicate solution is kept constant until almost complete neutralization. The buffering capacity of silicate solutions increases with increasing ratio of silica to alkali.
|
