Alkali phosphating

The third main type of alkalising agent is the alkali phosphate. Sodium mono-, di- and triphosphates in appropriate proportions may be used to achieve the desired conditions. In addition to their use to prevent scale phosphates have the advantage for corrosion control of being pH buffers so that they limit the attainable concentration of free hydroxide ion in solution and so restrain the scope for corrosion of the caustic type. 

The demand for alkali, phosphate, and/or polymer internal chemical treatments becomes significant, and unless extremely good control over BW chemistry and boiler plant operations is provided, the result most likely will be a scaled boiler, higher fuel costs, and reduced efficiency. A softener is required under these circumstances. 

For cleaning grease from metal surfaces, a strong alkali media (soda ash, borax, or alkali phosphates or silicates) are needed. However, these alone cannot effectively remove baked-on grease from metal surfaces. However, mixtures of soda and emulsifiers are found to be effective. 

The 7-lactones described below can be prepared in good yield in a one-step process by radical addition of primary fatty alcohols to acrylic acid, using di-tert-butyl peroxide as a catalyst. A patent claims a high yield when the reaction is carried out in the presence of alkali phosphates or alkali sulfates [196]. 

Partial replacement of cations when using excess of alkali phosphate was at first interpreted by supposing that the cations were in part bound as a complex with the polyphosphates. This led to incorrect conclusions regarding the molecular size of polyphosphates, which persist even now in the designation of Graham s salt as hexametaphosphate. The correct interpretation of these very complicated relationships stems from the discovery that in dilute solutions of polyphosphates even salts of the alkali metal ions are only partially dissociated—up to a maximum of 30-40% 260, 280, 282, 288, 333). The degree of dissociation a for alkali polyphosphates depends on many factors. Thus, for example, the effective degree of... 

J. T. Way, and T. Twynam heated Thomas slag with soda, and extracted the alkali phosphate with M ater. N. A, Helouis and M. Rychonnet, L. Imperatori, and F. Jean calcined a mixture of the phosphate with sodium sulphate and carbon C. Schwarz, and M. Boblique heated the mineral with iron so as to make ferric phosphate, which was then heated with sodium sulphate and carbon. In each of these cases the alkali phosphate was leached from the mass. M. Drevermann treated the iron phosphate with sodium sulphide, C. Clemm with potassium sulphide. 

Chromium phosphate [16453-74-0], CrP04-3 H20, Mr 201.0, is produced from chromium(III) salts and alkali phosphates. The physical and chemical properties are listed in Table 40 important areas of use are given in Table 39, [5.72],... 

Pwpureo Series.—These are prepared by dissolving vanadium pentoxide in solutions of alkali phosphates. The following are known —3... 

Iron Browns. Iron browns are often prepared by blending red, yellow, and black synthetic iron oxides to the desired shade. The most effective mixing can be achieved by blending iron oxide pastes, rather than dry powders. After mixing, the paste has to be dried at temperatures around 100°C, as higher temperatures might result in the decomposition of the temperature-sensitive iron yellows and blacks. Iron browns can also be prepared direcdy by heating hydrated ferric oxides in the presence of phosphoric acid, or alkali phosphates, under atmospheric or increased pressure. The products of precipitation processes, ie, the yellows, blacks, and browns, can also be calcined to reds and browns. 

The colour of the ash, its solubility in hydrochloric acid, and its neutrality or alkalinity are noted a qualitative analysis may be made, with reference especially to the silica, alumina, ferric oxide, lime, magnesia, alkalies, phosphates, carbonates, sulphates and chlorides. 

The first proposals for the employment of electrical heating in the production of phosphorus were made by Headman, Parker and Robinson.5 The simultaneous production of an alkali silicate by heating alkali phosphate, silica and carbon in a regenerative furnace was patented by Folie-Desjardins.6 In the Readman-Parker-Robinson process, as worked later, the phosphate, carbon and fluxes, previously heated to a high temperature, are introduced into the upper part of an electric furnace made of iron lined with refractory bricks and fitted with condensing pipes in its upper part. The gases pass through a series of copper condensers, the first of which contains hot water, the others cold water (or see p. 9). It has been found advisable to replace... 

Determination of Orthophosphates.—(1) With Silver Nitrate.— This depends upon the precipitation of silver orthophosphate in solutions of low and controlled acidity. In the assay of commercial 85 per cent, phosphoric acid of density 1-710 the syrup is diluted to a convenient volume and an aliquot part is taken which contains about 0-1 gram of H3P04. It is neutralised to phenolphthalein with approximately decinormal alkali (free from chloride). 50 c.c. of decinormal silver nitrate are then added while the solution is kept neutral to litmus by stirring in zinc oxide or a suspension of the hydroxide. The whole or a measured part of the filtered solution is acidified with nitric acid and, after the addition of ferric alum, the unused silver nitrate is titrated with standard decinormal ammonium thiocyanate in the usual manner. Alkali phosphates may also be determined in this way. 

Next to the acidic alkali phosphates, alkaline earth orthophosphates are of interest, because they represent many CBPC products, such as CaH2P04-H20 and MgH2P04 2H20. They are also the result of an acid-base reaction between an acid phosphate and an oxide containing an alkaline earth metal, such as Ca and Mg. They exhibit the same structure... 

When acidic alkali phosphates are reacted with alkaline earth oxides such as CaO and MgO, we obtain CBPCs of Ca and Mg and most common structures of the reaction products fall into the category of apatites. Apatites are most common in natural minerals. 

Studies of Alkali Phosphate and Phosphorus Chemistry Important to Magnetohydrodynamics Combustion... 

These results show that the Inclusion of alkali phosphate species in MHD conductivity models causes a large increase in the predicted free electron concentration. Unfortunately, the large uncertainties in the thermodynamic data preclude a quantitative... 

Alkali phosphates are typically prepared by the dehydration of crystalline orthophosphates. The phosphate building block... 

Chromium may also be completely precipitated as the phosphate, CrPOj, by the addition of an alkali phosphate in presence of sodium acetate. The method gives satisfactory results with the green and violet chlorides, sulphates, and acetates, but not with oxalates (see p. 87). 

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