Slags, basic

Since most of the high-phosphorus iron ores occur in Western Europe, most of the basic slag is produced and used there. A typical range of composition for high-grade basic slag is given in Table 14.6. 

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Fig. 8. World trends in types of phosphate fertilizers consumed, where (—) represents ammonium phosphates and multinutrient compounds (— normal superphosphate ( ), triple superphosphate and (— —), basic slag and raw rock.

Dead-burned magnesia, characterized by large crystaUite size and very low chemical reactivity, is resistant to the basic slags employed in the metals refining industry. It reacts very slowly with strong acids, and does not readily hydrate or react with carbon dioxide unless finely pulverized. 

Forsterite Refractories. Refractories made from forsterite, Mg2Si04, resist alkah attack and have good volume stabiUty, high temperature strength, and fak resistance to basic slags. Uses include nonferrous metal furnace roofs and glass-tank refractories not in contact with the melt, ie, checkers, ports, and uptakes. 

Carbon brick and block ate used to line the cupola well (73) or cmcible. When properly installed and cooled carbon linings last for many months or even years of intermittent operation. Their resistance to molten iron and both acid and basic slags provides not only insurance against breakouts but also operational flexibility to produce different iron grades without the necessity of changing refractories. Carbon is also widely used for the tap hole blocks, breast blocks, slagging troughs, and dams. 

Eertilization with basic slags of about 5 mg/kg Cr(VI), which is above the threshold for waste deposition sites (2 mg/kg), did not results in detectable Cr(VI) in soils. 

Reducing Atm Carbon Stability to Acid Slags Basic Slags Molten Metals... 

Basic slag used to be a popular fertiliser for supplying phosphate, but it also had liming value and contained some trace elements. However, the older steel-making processes are now out-of-date and basic slag is much less freely available. The consequence of this is that soils in Britain are becoming more acidic. 

Basic Open Hearth A version of the Open Hearth process for steelmaking in which the hearth is made from calcined dolomite (calcium and magnesium oxides). The sulfur and phosphorus impurities in the raw materials are converted to basic slag, which is separated from the molten steel. First operated in 1882 at Alexandrovsky, near St. Petersburg, Russia, and at Le Creusot, France. It was the major steelmaking process in the world in the first half of the 20th century. See Thomas. 

Procedure (analysis). Dilute the basic slag extract to give ( =25 ml) a solu-... 

In a definitive series of experimental investigations H. N. Wilson showed that the quinolinium salt, (C isNJ fPCV I2M0O3]3- was anhydrous, contained exactly 12 moles of molybdenum trioxide per mole of phosphate, that the precipitate had a negligible solubility and could be dried to constant weight in two hours at 105 °C. This precipitate also lent itself to a precise alkalimetric titration. In the presence of citric acid interference by silica was inhibited so that the method was admirably suitable for the analysis of basic slags or fertilizers.34... 

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