Sulfuric acid production process technology

Centaur A process for reducing sulfur dioxide emissions from sulfuric acid plants. An activated caibon with both absorptive and catalytic properties is used. The technology uses fixed beds of Centaur carbon to oxidize sulfur dioxide to sulfuric acid in the pores of the carbon. The sulfuric acid is recovered as dilute sulfuric acid, which is used a make-up water in the sulfuric acid production process. Developed by Calgon Carbon Corporation in the 1990s. Calgon Carbon and Monsanto Enviro-Chem operated a Centaur pilot plant at an existing sulfuric acid facility in 1996. 

The Kivcet process is robust and highly flexible in the range of possible feed materials, from high-grade concentrates through to secondary leach residues. It produces a low volume of smelter gas rich in SO2 and suitable for sulfuric acid production. It is also well contained with minimal opportunity for environmental emissions, particularly in comparison with sinter plant-blast furnace technology. 

Citric Acid Separation. Citric acid [77-92-9] and other organic acids can be recovered from fermentation broths usiag the UOP Sorbex technology (90—92). The conventional means of recovering citric acid is by a lime and sulfuric acid process ia which the citric acid is first precipitated as a calcium salt and then reacidulated with sulfuric acid. However, this process generates significant by-products and thus can become iaefficient. 

Production Technology. Processes for extraction of P2O3 from phosphate rock by sulfuric acid vary widely, but all produce a phosphoric acid—calcium sulfate slurry that requires soHds-Hquid separation (usually by filtration (qv)), countercurrent washing of the soHds to improve P2O3 recovery, and concentration of the acid. Volatilized fluorine compounds are scmbbed and calcium sulfate is disposed of in a variety of ways. 

The most efficient processes in Table I are for steel and alumintim, mainly because these metals are produced in large amounts, and much technological development has been lavished on them. Magnesium and titanium require chloride intermediates, decreasing their efficiencies of production lead, copper, and nickel require extra processing to remove unwanted impurities. Sulfide ores produce sulfur dioxide (SO2), a pollutant, which must be removed from smokestack gases. For example, in copper production the removal of SO, and its conversion to sulfuric acid adds up to 8(10) JA g of additional process energy consumption. In aluminum production disposal of waste ciyolite must be controlled because of possible fiuoride contamination. 

These three steps all produce significant amounts of waste. First, as discussed earlier, the nitration process results in the production of spent sulfuric acid. In the past the company had been able to sell much of this material to the coke and steel industries but declining demand meant that the acid now required disposing of, at additional cost. At the time green catalytic nitration technology was becoming available with clay, zeolite and lanthanide catalysts all providing possible alternatives to the use of sulfuric acid (see below). Improved selectivity to the desired para-isomer is an added benefit of some of these catalytic systems. However on the... 

Titanium dioxide (E171, Cl white 6) is a white, opaque mineral occurring naturally in three main forms rutile, anatase, and brookite. More than 4 million tons of titanium dioxide are produced per year and it is widely used for industrial applications (paints, inks, plastics, textiles) and in small amounts as a food colorant. ° "° Production and properties — Titanium oxide is mainly produced from ilmenite, a titaniferous ore (FeTiOj). Rutile and anatase are relatively pure titanium dioxide (Ti02) forms. Titanium oxide pigment is produced via chloride or sulfate processes via the treatment of the titanium oxide ore with chlorine gas or sulfuric acid, followed by a series of purification steps. High-purity anatase is preferred for utilization in the food industry. It may be coated with small amounts of alumina or silica to improve technological properties. 

The process consumes the sulfuric acid and produces a waste. product, ammonium bisulfate, so it is expensive. So when propylene oxidation technology was developed, it became the preferred route. 

Reactive absorption is probably the most widely applied type of a reactive separation process. It is used for production purposes in a number of classical bulk-chemical technologies, such as nitric or sulfuric acid. It is also often employed in gas purification processes, e.g., to remove carbon dioxide or hydrogen sulfide. Other interesting areas of application include olefin/paraffin separations, where reactive absorption with reversible chemical complexation appears to be a promising alternative to the cryogenic distillation (62). 

Reactive absorption is very old as a processing technique and has been used for production purposes in a number of classical bulk-chemical technologies, such as nitric or sulfuric acid. The Raschig process for the production of hydroxylamine, an important intermediate in classical caprolactam technologies (Stamicarbon, Inventa), is also an example of a multistep reactive absorption process. Here, water, ammonia, and carbon dioxide react together in an absorption column to give a solution of ammonium carbonate, which subsequently forms an alkaline... 

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