Sulfuric acid production technical grade

The principal vanadium-bearing ores are generally cmshed, ground, screened, and mixed with a sodium salt, eg, NaCl or Na2C02- This mixture is roasted at ca 850°C and the oxides are converted to water-soluble sodium metavanadate, NaVO. The vanadium is extracted by leaching with water and precipitates at pH 2—3 as sodium hexavanadate, Na V O, a red cake, by the addition of sulfuric acid. This is then fused at 700°C to yield a dense black product which is sold as technical-grade vanadium pentoxide. This product contains a minimum of 86 wt % V20 and a maximum of 6—10 wt % Na20. 

Then 75 ml of ice-cold sulfuric acid is added with rapid stirring, followed by the rapid addition of a solution of 17 gm of sodium dichromate (technical grade) in 50 ml of water. The mixture is vigorously stirred for a few minutes and is then filtered. The brown precipitate is washed with 1 liter of cold water and transferred to a steam-distillation apparatus. The product, being volatile with steam, is purified by steam distillation. The purified m-dinitrosobenzene solidifies in the distillate and is finally isolated by filtration yield 8.3 gm (51 %), m.p. 144°-145°C (this product is said to be monomeric in nature). 

The ammonium bicarbonate used was a technical grade product manufactured in the United Kingdom by the Imperial Chemical Industries, Ltd. Titration of this product for ammonia with sulfuric acid to the methyl orange end point indicated a purity of approximately 100%. 

A sulfuric acid plant generally produces technical grade acid. However, plant management can explore the markets for the following products since they can realise much higher prices and they can be produced by adding on certain equipment as outlined below. This will improve the financial profitability of the organization. 

In spite of the large quantities of sulfuric add offered, a weD-defined demand exists for add of special purity. This means low mercury acid with 0.1 ppmw Hg is at a premium (5 DM per tonne in 1994) over typical merchant-grade product, which has up to 0,5 ppmw mercury jll]. A specification for technical-grade sulfuric acid is given in Table 11.8. 

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