Principles of the Manufacturing Process

In the stoichiometric sodium salt of silicic acid, Na4Si04, the silica soda ratio is 1 2. In silicate solutions having a sihca soda ratio of 3.25, much less sodium hydroxide is present to ionize off the weak hydrogen 

Several types of oligomers must exist for any particular ratio since they must of necessity be made up of whole numbers of silica units. The numbers of silica units in each must vary and the equilibrium number of each must vary to accommodate the variations in the overall ratio. Thus every particular ratio of sodium silicate solution has it s own equilibrium distribution of oligomers at a given Silica concentration and temperature. The distribution of oligomers tends to define the viscosity of the solution. The stability of these units would appear to be fairly substantial. It is observed that if the ratio is adjusted it may take some hours or days before a constant viscosity is reached. 

This could have some ramifications in the manufacture of colloidal sihca. Typically, sodium silicate is diluted prior to being deionized and polymerized. It is likely that the equilibrium distribution of oligomers will be different depending on whether the solution is freshly made or has been allowed to stand diluted for some time. While it is not clear that this variation in silica sources could have a significant effect on the properties of the colloidal silica made from them, it is a variable 

When many of us took our first general chemistry course we were told, as a rule of thumb, that there were no insoluble sodium salts. However, the sodium form of an ion exchange resin can be thought of as an insoluble salt of sodium, since the sodium is removed from solution and is bound to the polymer. When washed with a strong acid, such as sulfuric acid, the sodium is released as the 

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Although many commercial processes have heen developed since the first electrolytic isolation of Mg metal hy Davy and Faraday, and Bussy, hy chemical reduction, the principles of the manufacturing processes have not changed. At present, the metal is most commonly manufactured by electrolytic reduction of molten magnesium chloride, in which chlorine is produced as a by-product. In chemical reduction processes, the metal is obtained by reduction of magnesium oxide, hydroxide, or chloride at elevated temperatures. 

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