Slags properties

Gaskell, D. R., Research Needs Slag Properties and Chemistry, Steel Res., 60 182 (1989)... 

Ashing Ashphaltenes Ash properties Ash slagging Asmatane Mst ASN As203... 

Additioaal components such as alumiaa [1344-28-1] are also added to obtaia more favorable thermodyaamics, and to obtain a slag having favorable properties. Many different feed and slag compositions exist, as do alternative reductants for ferrosiUcon. It is also theoretically possible to manufacture magnesium metal by the reduction of MgO with carbon. 

Mechanical Properties. The physical properties of a particular refractory product depend on its constituents and manner in which these were assembled. The physical properties may be varied to suit specific appHcations. For example, for thermal insulations highly porous products are employed, whereas dense products are used for slagging or abrasive conditions. 

Uses. In spite of unique properties, there are few commercial appUcations for monolithic shapes of borides. They are used for resistance-heated boats (with boron nitride), for aluminum evaporation, and for sliding electrical contacts. There are a number of potential uses ia the control and handling of molten metals and slags where corrosion and erosion resistance are important. Titanium diboride and zirconium diboride are potential cathodes for the aluminum Hall cells (see Aluminum and aluminum alloys). Lanthanum hexaboride and cerium hexaboride are particularly useful as cathodes ia electronic devices because of their high thermal emissivities, low work functions, and resistance to poisoning. 

This wear is caused primarily from high thermal and mechanical stress, chemical attack, attack by iron and slag, oxidation, and severe thermal shock. Thus the design of the hearth wall and the concepts employed ate just as important as the carbon or graphite materials chosen for the refractory material. Despite their benefits and properties, no carbon or graphite material can overcome the problems of an improper hearth wall design concept. 

MiscelDneous. Other important properties are resistance to thermal shock, attack by slag, and, in the case of refractories (qv), thermal expansion. For whiteware, translucency, acceptance of glazes, etc, may be extremely important. These properties depend on the clay mineral composition, the method of manufacture and impurity content. 

Coal properties influence pulverizer capacity and the sizing of the air heater and other heat-recovery sections of a steam generator. Furnace size and heat-release rates are designed to control slagging characteristics. Consequently, heat-release rates in terms of the ratio of net heat input to plan area range from 4.4 MW/m" (1.4 X 10 Btii/[h ft ]) for severely slagging coals to 6.6 MW/m (2.1 X 10 Btii/[h ft ]) for low-slagging fuels. 

As in die case of die diffusion properties, die viscous properties of die molten salts and slags, which play an important role in die movement of bulk phases, are also very stiiicture-seiisitive, and will be refeiTed to in specific examples. For example, die viscosity of liquid silicates are in die range 1-100 poise. The viscosities of molten metals are very similar from one metal to anodier, but die numerical value is usually in die range 1-10 centipoise. This range should be compared widi die familiar case of water at room temperature, which has a viscosity of one centipoise. An empirical relationship which has been proposed for die temperature dependence of die viscosity of liquids as an AiTlienius expression is... 

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