Magnesium hydroxide slurry

Martin Marietta Magnesia Specialties, Inc. (Pittsburgh, Peimsylvania, formerly Clearwater, Inc.) hydrates MgO to produce magnesium hydroxide slurry containing 58% soflds (73). 

Bulk density is 1.49 kg/L for 57% solids slurry with a Mg(OH)2 loading of 0.85 kg/L. The properties of some magnesium hydroxide slurries are given in Table 12. 

Instmmentation and control guidelines for processes utilizing magnesium hydroxide and other slurries have been outlined (82). An experimental deterrnination of the accuracy of magnetic dow meters for magnesium hydroxide slurries d owing in pipelines (qv) has been reported (83). 

Slurry Viscosity. Viscosities of magnesium hydroxide slurries are determined by the Brookfield Viscometer in which viscosity is measured using various combinations of spindles and spindle speeds, or other common methods of viscometry. Viscosity decreases with increasing rate of shear. Fluids, such as magnesium hydroxide slurry, that exhibit this type of rheological behavior are termed pseudoplastic. The viscosities obtained can be correlated with product or process parameters. Details of viscosity deterrnination for slurries are well covered in the Hterature (85,86). 

Use magnesium hydroxide slurry to control pH, rather than concentrated sodium hydroxide (Englund, 1991a). 

Magnesium hydroxide slurry, 75 403, 407 properties of, 75 404t viscosity of, 75 405-406 Magnesium iodide, 75 407-409 physical properties of, 75 408t Magnesium iodide dietherate, 75 408 Magnesium ions soap and, 22 724 sources for, 75 328... 

Ishikawa, M Yoshioka, T Uchida, M. and Okuwaki, A., Hydrolysis of waste poly(ethylene terephthalate) in magnesium hydroxide slurry, presentation (ENVR 209) given at the International Chemical Congress of Pacific Basin Societies, Honolulu, HI, 14-19 December, 2000. 

This technology involves the addition of chemical reagents to cause insoluble compounds to form. A common method nsed to precipitate metal ions is pH adjustment. The desired pH is one in which the metals exhibit low solubilities in water and therefore precipitate. Common reagents nsed for pH adjnstment include aUcahs such as lime, caustic soda, or magnesium hydroxide slurries to precipitate metal hydroxides. Sulfides such as sodium sulfide or ferrous sulfide slurries are often nsed to precipitate metal snlfides. Other reagents, such as xanthates, can also be nsed to precipitate metal ions. 

Using magnesium hydroxide slurry to control pH instead of concentrated sodium hydroxide solutions, which are corrosive to humans and relatively hazardous to handle. 

With magnesium-, sodium-, or ammonium-based sytems, the bisulfite and sulfite salts are all soluble at all proportions in the presence of sulfurous acid. Even magnesium sulfite, with a solubility of about 1.25 g/100 mL, cold, is about 160 times as soluble as calcium sulfite at the same temperature and its solubility increases with temperature. So liquor preparation with these sulfite salts is easier, whether for acid sulfite, bisulfite, or NSSC pulping conditions, and even for experimental tests under alkaline conditions. For ammonium-based systems, ammonium hydroxide is contacted with a sulfur dioxide gas stream for liquor preparation. Magnesium-based systems use a magnesium hydroxide slurry to contact the sulfur dioxide gas stream. Sodium-based systems normally employ sodium carbonate lumps in a sulfiting tower, in a method similar to that used for NSSC liquor preparation. Sodium hydroxide may also be used if available at low cost. 

Synthetic magnesium hydroxide slurry is produced using either seawater- or brine-precipitated magnesium hydroxide filter cake that has the desired solids content of the finished slurry. To produce pumpable slurry, the... 

Another common method of producing magnesium hydroxide slurry is by reacting magnesium oxide in water in excess of that require for theoretical hydration ... 

Testing and Quality Control of Magnesium Hydroxide Slurry... 

Viscosity There are many different methods of determining the viscosity of a fluid, however, the quickest method for running routine QC checks is to use a Brookfield rotational viscometer either the RV or LV models are suited to the range of viscosities normally encountered for magnesium hydroxide slurry. 

Magnesium hydroxide slurry can be used to help combat both the generation and release of H2S gas into the headspace, as well as mitigate the effect of Thio-Z ac///ws-generated sulfuric acid on the sewer crown and is sold under the... 

This reaction of the layer of Mg(OH)2 sprayed over Thiobacillus effectively deprives the bacteria of their source of sulfide, which again will inactivate them. Film forming and adhesion additives can be added to the magnesium hydroxide slurry to make the layer sprayed onto the sewer crown surfaces more resistant to surcharging so that the protection is not washed away as soon as full pipe flow occurs. 

This method is used for measuring the solids content MgO per gallon or pounds MgO per thousand gallons in magnesium hydroxide slurry of varying concentrations. 

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