Sodium Silicofluoride

Fluoridizing roasting or fluorination is similar to chlorination, and is widely used in the treatment of several rare metal ores. Beryl, the most important ore of beryllium, can be opened by fusing with sodium silicofluoride at 850 °C ... 

In place of sodium silicofluoride, sodium ferric fluoride (Na3FeF6) can also be used for fluorination ... 

Sodium ferric fluoride is obtained as a byproduct in the solution processing of Na2BeF6 leach liquor. It is used for substituting for sodium silicofluoride (to an extent of up to 60%) in the ore fusion reaction. 

A preservative for concentrated natural rubber latex, the use of which eliminates the ammoniation process necessary with ammonia-preserved latex. See Low Ammonia Latices. Sodium Silicofluoride... 

The different types of admixtures, known to reduce alkali-aggregate reactions, can be divided into two groups those that are effective in reducing the expansion due to the alkali-silica reaction, and those that lower expansions resulting from the alkali-carbonate reaction. For the alkali-silica reaction, reductions in the expansion of mortar specimens have been obtained with soluble salts of lithium, barium and sodium, proteinaceous air-entraining agents, aluminum powder, CUSO4, sodium silicofluoride, alkyl alkoxy silane,... 

Alkyl alkoxy silanes have been found to be very effective in reducing alkali-aggregate expansion [11] (Fig. 6.4). Of the silanes used in the study, hexyl trimethyl siloxane and decyl trimethoxyl silane were found to be more effective in decreasing the expansion than the others. In the same study, Ohama et al. [11] investigated the effect of sodium silicofluoride, alkyl alkoxy silane, lithium carbonate, lithium fluoride, styrene-butadiene rubber latex and lithium hydroxide on compressive strength and the expansion of mortar containing cement with 2% equivalent Na20. The reduction of the level of expansion shown in Fig. 6.4 with the siloxanes was attributed to... 

Precipitated silicas having properties matching those from the conventional sodium silicate route are said to be possible (79). The hydrofluosilicic acid that is generated can be recycled in the system, or can be used to manufacture sodium silicofluoride or ammonium fluoride. 

Sodium selenate (see Selenium and selenium compounds) Sodium selenite (see Selenium and selenium compounds) Sodium silicofluoride (see Fluorides)... 

Oils Edible Safflower Potassium Binoxalate Ammonium Chloride Salicylic Acid Ammonium Chloride Lead Acetate Potassium Binoxalate Sodium Silicofluoride Ammonium Carbonate Fluocilicic Acid P-Dichlorobenzene Ammonium Phosphate Sec-Butyl Acetate Sec-Butyl Alcohol Calcium Phosphate Selenium Trioxide Selenium Dioxide Selenium Dioxide Selenium Dioxide Selenium Trioxide Antimony Trioxide Calcium Hypochlorite Carbaryl Cyclohexanone Charcoal... 

The chlorate is purified from the chloride by fractional crystallization. In Muspratt s method10 magnesium oxide suspended in water is substituted for sodium hydroxide, the solution being concentrated after treatment with chlorine, and sodium carbonate added to precipitate the magnesium for further use. The sodium chlorate crystallizes from the mother-liquor. The salt is also formed from potassium chlorate by double decomposition with substances such as sodium hydrogen tartrate and sodium silicofluoride, as well as by the electrolytic decomposition of sodium-chloride solution under certain conditions11 (p. 97). 

The names sodium borohydride and lithium aluminum hydride (8) are not constructed on any established nomenclature pattern unless it be rapidly disappearing one represented by sodium silicofluoride and potassium ferrocyanide. 

Three most commonly used fluoride chemicals in the United States for fluoridation are sodium fluoride, sodium silicofluoride, and hydrofluosilicic acid. When applied to drinking water, they should meet the AWWA Standard B703-00 and B701-99 and should be NSF/ANSI Standard 60 certified. These sfandards ensure quality of the chemicals and limit the amount of impurities in the chemical, such as heavy metals (lead) (3,14,15). 

The first batch of sodium silicofluoride was sampled and subjected to particle-size analysis (see Section 4.3) with the following results 3% retained on 100-mesh sieve, 9% passes through the 325-mesh sieve. The moisture content was 0.05%. Applying the feedability formula yields ... 

To ensure good handling and feeding characteristics for dry chemicals, it is important that the dry chemical adhere to graduation specifications. The size gradation for crystalline (coarse) sodium fluoride for use in a downflow saturator (see the Section 5) should be in the 20-60-mesh range (0.85-0.25 mm), and powdered sodium silicofluoride... 

A 100 g sample of sodium silicofluoride was used in a sieve analysis. Table 7 presents the amounts retained in the 100,140, 200, and 325 sieve meshes and in the pan. Assuming the moisture content of this particular material was 0.05% or less, applying the feedability formula yields ... 

The dissolution of sodium silicofluoride in the solution tank of a dry feeder package unit can be accomplished by a jet mixer, but again a mechanical mixer is preferred. Because of the low solubility of sodium silicofluoride, particularly in cold-water applications, and the limited retention time available for dissolution, violent agitation is needed to prevent the slurry discharge. The preferred construction materials for a mechanical mixer are 316 stainless steel, plastic-coated steel, and Hastelloy-C (15). 

Scandium is usually present in rare earth minerals in small amounts (the rare mineral thortveitite containing 37 per cent SC2O3 is an exception). It collects in the soluble end of the bro-mate fractionations, but it is easily separated from the other soluble salts by the fact that it is the least basic of the whole group. Consequently, fractional precipitation or fusion of the nitrates concentrates the scandium rapidly. Scandium may also be precipitated from boiling acid solution by sodium silicofluoride its double ammonium tartrate and double potassium sulfate are also difficultly soluble. 

---