Magnesium phosphates

FLUORINECOMPOUNDS,INORGANIC - MAGNESIUT (Volll) Ammonium magnesium phosphate [7785-21-9]... 

PEROXIDES AND PEROXIDE COMPOUNDS - INORGANIC PEROXIDES] (Vol 18) Magnesium phosphate [10043-83-1]... 

Hard-burned magnesias may be used in a variety of appHcations such as ceramics (qv), animal feed supplements, acid neutralization, wastewater treatment, leather (qv) tanning, magnesium phosphate cements, magnesium compound manufacturing, fertilizer, or as a raw material for fused magnesia. A patented process has introduced this material as a cation adsorbent for metals removal in wastewater treatment (132). 

An aqueous solution of mono ammonium phosphate [10361-65-6] reacts with MgO to form ammonium magnesium phosphate hexahydrate [15490-91-2], NH MgPO 6H20. Several other species of hydrated phosphates are created during this reaction which takes place quickly and produces compounds that have desirable properties as cementing agents. The hexahydrate is the most prevalent. Properties are given in Table 22. 

Dehydration takes place initially at 50°C then proceeds up to 160°C, producing ammonium magnesium phosphate monohydrate [16674-60-5] ... 

A wide variety of precipitates form in cooling water systems carbonates, silicates, sulfates, and phosphates are common. Below and slightly above 212°F (100°C), calcite, aragonite, gypsum, hydroxyapatite, magnesium phosphate, anhydrite, and serpentine are commonly encountered (see Table 4.1). 

A 0-9% salt solution is considered to be isotonic with blood. Other electrolytes present include bicarbonate ions (HCOj ) and small amounts of potassium, calcium, magnesium, phosphate, sulphate and organic acid ions. Included among the complex compounds and present in smaller amounts are phospholipids, cholesterols, natural fats, proteins, glucose and amino acids. Under normal conditions the extracellular body fluid is slightly alkaline with a pH of 7-4. ... 

Crucibles fitted with permanent porous plates are cleaned by shaking out as much of the solid as possible, and then dissolving out the remainder of the solid with a suitable solvent. A hot 0.1 M solution of the tetrasodium salt of the ethylenediaminetetra-acetic acid is an excellent solvent for many of the precipitates [except metallic sulphides and hexacyanoferrates(III)] encountered in analysis. These include barium sulphate, calcium oxalate, calcium phosphate, calcium oxide, lead carbonate, lead iodate, lead oxalate, and ammonium magnesium phosphate. The crucible may either be completely immersed in the hot reagent or the latter may be drawn by suction through the crucible. 

Ammonium cerium (IV) sulphate 380 Ammonium iron (III) sulphate indicator, 354 Ammonium magnesium phosphate, thermal analysis of 498... 

Phosphites, D. of as ammonium magnesium phosphate or as magnesium pyrophosphate, (g) 497 as mercury(I) chloride by mercury(II) chloride, (g) 486 Phosphorescence 731... 

This back-pressure further increases to 8.5 inches for magnesium phosphate... 

Contaminants such as oil, magnesium phosphate, and hematite have a natural binding action that exacerbates the fouling problem and may result in the rapid agglomeration of tube deposits in WT boilers and fire-tube bridging in FT boilers. 

In particular, where polyphosphate is added either to the MU waterline (say, as a stabilizer against the risks of after-precipitation) or to the FW line or FW tank (as a precipitating treatment for residual hardness), there is some risk of FW line phosphate deposits developing. Such deposits are likely to be primarily composed of hard, intractable calcium phosphate [tricalcium phosphate Ca3(P04)2] scale, but they may include magnesium phosphate [Mg3(P04)2] and other insoluble phosphates and hydroxides. The risk of precipitation and subsequent deposition is increased where the pH is below 8.3, if the FW line is particularly long, or when the FW temperature is high. 

Basic) Magnesium phosphate Magnesium hydroxy-phosphate 3Mg3(P04)2-Mg(0H)2 Forms with hematite in passivated films at lower temperatures. 

The BW pH level should be above 10.2 to ensure that hydroxyapatite preferentially precipitates. Also, where magnesium is present, the pH level should be above 10.5 so that magnesium hydroxide [brucite, Mg(OH)2] precipitates, rather than the stickier and more adherent magnesium phosphate [Mg3(P04)2]. In any event, where possible, it is... 

This variation was designed for lower grade FW where the risk of hardness leakage may occur (e.g., in marine boilers). Under circumstances of minimal reserve alkalinity and a hardness leak, magnesium hydroxide does not develop rather, the stickier magnesium phosphate [Mg3(P04)2] will precipitate in the boiler and has an unfortunate preponderance to adhere to hot boiler tubes. 

It is important to ensure that magnesium phosphate is not precipitated in the boiler water because it may cause sludges to adhere... 

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