Silicofluorides

Antimony compounds are based on antimony, an element that exhibits both metal and nonmetal properties. Many of its compounds are toxic and corrosive, particularly the soluble salts. They include antimony iodide and antimony perchloride. Some antimony compounds decompose in water to produce toxic gases e.g., antimony sulphate decomposes to sulphur dioxide while antimony bromide produces bromine gas. 

Arsenic compounds are based on the metalloid arsenic. They are extremely toxic and include the arsenates, those that contain the AsO/ group 

Tellurium compounds are toxic. They include tellurium sulphide and tellurium dioxide. 

Dissociation of many inorganic acids yields a variety of salts. 

Chlorine forms a number of ions with oxygen, all of which are strong oxidizing agents. They react similarly to bromates, evolving chlorine gas in contact with acids. They include 

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Chemical Designations - Synortyms Zinc fluosilicate Zinc hexafluorosilicate Zinc silicofluoride hexahydrate Chemical Formula ZnSiFu fiHiO. 

Inorganic Nomenclature. Compounds may be named in German merely by compounding the names of the elements as, Jodkalium (potassium iodide), SHiziumfiuorwasserstoff (hydrogen silicofluoride, fluosihcic acid). Words formed from the names of two elements are usually to be translated by giving the -ide ending to the first part (Jodkalium, potassium iodide). 

High-quality concrete slabs that have been well finished should not give rise to dusting. Complete avoidance of dust, however, will only be achieved by the addition of a resin or chemical sealer. Chemical sealers (such as silicofluorides and silicates) give little increased abrasion resistance, and can themselves be prone to dusting on over-application. 

Using pulse plating techniques with a duty cycle of 50%, it is also possible to produce crack-free chromium deposits from a sulphate- or silicofluoride-catalysed solution with a hardness similar to deposits obtained by direct currenf . A high frequency (2 000-3 000 Hz) is required to give the hardest deposits at a current density of 40 A/dm and a temperature of 54°C. It is important to avoid conditions that will co-deposit hydrides. 

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. 

Masters RD and Coplan MJ. 1999. Water treatment with silicofluorides and lead toxicity. International Journal of Environmental Studies (in press). 

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... 

However, the hydrogenation catalysts can be promoted also by compounds which are ineffective for the iron ammonia catalysts, e.g., by silica and silicates, silicofluorides, borates, and phosphates. An interesting type of hydrogenation catalysts was found in the form of zeolites which by ion exchange were impregnated with heavy metal salts. 

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. 

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