Refining agent

Because the basic-oxygen process uses a refining agent containing practically no nitrogen, the product has a low nitrogen content. Oxygen residues depend on the carbon content. 

Alloys containing zirconium as a grain-refining agent have the iron content automatically reduced to about 0 004% by settling out of impurities during the alloying procedure. 

The synthetic method used in preparing a particular boride phase depends primarily on its intended use. Whereas for basic research borides of high purity are desirable, for industrial applications, e.g., in coatings, tools and crucibles, as a refining agent in metallurgy or in control rods in nuclear energy plants, pure borides are unnecessary. 

Yellow phosphorus ignites in molten ammonium nitrate, and mixtures of phosphorus with ammonium nitrate, mercuiy(I) nitrate or silver nitrate explode on impact. Red phosphorus is oxidised vigorously when heated with potassium nitrate [1]. During development of new refining agents for aluminium manufacture, a mixture containing red phosphorus (16%) and sodium nitrate (35%) was being pressed into 400 g tablets. When the die pressure was increased to 70 bar, a violent explosion occurred [2],... 

Hydrogen is a primary chemical feedstock in the production of gasoline, fuel oils, lubricants, fertilizers, plastics, paints, detergents, electronics and pharmaceutical products. It is also an excellent metallurgical refining agent and an important food preservative. 

Another method to refine oils using milder silicate refining agent was recently reported. This process combines neutralization and adsorption and eliminates the use of centrifuges to remove free fatty acids from crude oils (it involves the addition of sodium silicate instead of sodium hydroxide, which allows for the removal of free fatty acids and protein-like materials by adsorption and filtration and avoids the use of more expensive centrifuges). The combined agglomerating and adsorptive characteristics of silicates allow for the removal of these impurities (81). 

Refining agents, 113,202 Refining of glass, 94,111 — 116 Reflection of light, 182 Refractive index,... 

Na2S04. = Na20 -b SO2 2 2 For chloride and fluoride refining agents ... 

The considerations dealt with so far have been concerned with gas bubbles of larger sizes (above about 10" mm). Bubbles of smaller sizes (called seed ) exhibit specific behaviour which may lead to spontaneous dissolution even without the effect of refining agents. The surface tension acting in the bubble walls produces increased pressure in the enclosed gas, given by the relationship... 

Calcium is utilized in the manufacture of special metals such as zirconium, thorium, uranium and the rare earths, as a refining agent in metallurgy (steel, copper, magnesium, tantalum, lead) and in the manufacture of calcium hydride (hydrogen source). 

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