Sulfuric acid production from elemental sulfur

Phosphoric acid and phosphate salts are produced either by oxidation of elemental phosphorous or by extraction of the phosphate mineral Ca3(P04)2 (apatite) with sulfuric acid. Production from elemental phosphorous is energetically more demanding and therefore capacities are increasingly shifting towards the extraction process. However, the production of food grade phosphoric acid from the natural mineral apatite requires additional separation and purification steps to remove heavy metals (such as e.g., Cu or As) from the crude phosphoric acid. Precipitation techniques and countercurrent extraction with organic solvents, such as n-butanol or diisopropyl ether, are applied for this purpose. 

Sulfuric acid is the most commonly used reagent for the recovery of uranium from ores, and vanadium is often recovered as a coproduct. The sulfuric acid used is either the by-product sulfuric acid produced at smelters or sulfuric acid produced from elemental sulfur. 

The fertilizer industry continues to improve its products to give higher and higher yields of nutrient to plants. Triple Super Phosphate fertilizer is made by first treating phosphate ore with sulfuric acid to make a crude form of phosphoric acid that is often referred to as green acid, because it is colored green and not because it has not been cured or ripened. The green acid is also called wet acid, to differentiate it from phosphoric acid made from elemental phosphorus. Phosphoric acid produced from elemental phosphorus is the purest of acids and it is called furnace acid. 

Owing to its excellent thermal and mechanical stability and its rich chemistry, alumina is the most widely used support in catalysis. Although aluminium oxide exists in various structures, only three phases are of interest, namely the nonporous, crys-tallographically ordered a-Al203, and the porous amorphous t]- and y-Al203. The latter is also used as a catalyst by itself, for example in the production of elemental sulfur from H2S (the Claus process), the alkylation of phenol or the dehydration of formic acid. 

Sulfuric acid production is one alternative to the manufacture of elemental sulfur from acid gas streams. If a market for the product acid can be found, sulfuric acid may be economically attractive relative to elemental sulfur (14,15). 

Smelter Acid. If acid is produced involuntarily, as in a smelter operation, it is possible to estimate the cost of acid production in the same manner as that for an elemental sulfur acid plant. To the smelter, however, acid output is simply a mandated concomitant of the process required to produce the metal. Depending on the location of the smelter, the sources of demand, the size of the market, and competition from other producers, the acid sale price may or may not be sufficiently high even to yield a positive net-back, much less a desired rate of return on investment for the acid portion of the operation. This situation does not necessarily lead to closure. Positive or negative, the effect should be registered only in the overall profitability of the entire smelter operation. 

The acid gas stream from the purification process is sent to a sulfur recovery unit which is usually a Stretford or a Claus unit. The product from these units is elemental sulfur. 

The annual production of sulfuric acid in the United States is approximately 4 X 1010 kg. (a) If the acid were all produced from elemental sulfur, what mass of sulfur would be used for the production of sulfuric acid (b) What volume of sulfur trioxide (at 25°C and 5.0 atm) is required for the annual production of sulfuric acid ... 

The simplicity of this process suggests that it should be used to the exclusion of the more complicated procedure involving the reaction between salt and sulfuric acid. However, producers of sodium hydroxide do not use their by-product chlorine in this manner if there is a sufficient demand for the elemental chlorine as such. Furthermore, if a profitable market for sodium sulfate exists, it may be cheaper to produce hydrochloric acid from salt and sulfuric acid than from the elements. Finally, another competitive aspect to this situation arises—the availability of by-product acid. 

Extraction hoods serve a number of useful purposes. These include removal of carbon dioxide and steam (the commonest combustion products) and of other, less desirable combustion products, such as sulfur dioxide and other acidic gases from some sample solutions, and of whatever elements were present in the samples. They also remove soot from excessively fuel-rich flames, which otherwise can make a real mess in the laboratory. It is unwise to run instruments for extended periods without fume extraction, even if there is nothing obviously toxic in the sample solutions. This is especially true for the nitrous oxide-acetylene flame. It is well worth considering interfacing the fume extraction switch with the instrument power supply, because it is easy to forget to turn on the extractor when everything else is automated. 

Hydrochloric acid is an aqueous solution of hydrogen chloride gas produced by a number of methods including the reaction of sodium chloride and sulfuric acid the constituent elements as a by-product from the electrolysis of sodium hydroxide and as a by-product during the chlorination of hydrocarbons. 

The production of sulfuric acid from elemental sulfur proceeds exothermically in all reaction steps. Per ton of 100% sulfuric acid a total of ca. 5.4 MJ of heat is produced. Most of this is utilized in the production of steam (1.1 t of high-pressure steam e.g. at 40 bar and 400°C per ton of 100% sulfuric acid). 

Regeneration of the uncomplexed citric acid at the same time as formation of an elemental sulfur product from the bisulfite anion is obtained by treating the absorption solution with hydrogen sulfide [41] (Eq. 3.30). 

Zinc is not attacked by air or water at room temperature, but the hot metal burns in air and decomposes steam, forming ZnO. Zinc is much more reactive than Cu (compare equations 21.104 and 21.92), liberating H2 from dilute mineral acids and from alkalis (equation 21.105). With hot concentrated sulfuric acid, reaction 21.106 occurs the products of reactions with HNO3 depend on temperature and acid concentration. On heating, Zn reacts with all the halogens to give ZnX2, and combines with elemental S and P. 

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