Steel production phosphoric acid used

Some of the alloys that are protected by anodic protection are stainless steel in phosphoric acid, steel in sulfuric acid, nickel in nitric acid, nickel alloys in nitrate solutions, and titanium in ammonia solution. Recently, anodic protection has been used to protect stainless steel heat exchangers used in the production of sulfuric acid [57]. The current requirement for some of the steels on which anodic protection has been applied is summarized by Sudbury and Locke [58]. Anodic protection has also been used in plants for the manufacture, storage, and transport of sulfuric acid. It reduces the iron dissolution in sulfuric acid to 1 ppm per day of storage. Portable anodic protection systems are used to stop iron dissolution during the transportation of sulfuric acid in trucks [57]. 

Effect of Propane to Oxygen Mole Ratio in Feed. Table IV gives the results for the propane and oxygen mole ratio ranging from 2 to 8. Stainless steel Reactor VII was used for these experiments after the phosphoric acid pretreatment the reaction temperature was 430°C. The product gas was cooled in the Liebig condenser at 2°C., and the condensate was analyzed. 

Among all the acids, phosphoric acid, H3PO4, is second only to sulfuric acid in industrial production. Two methods are commonly used. The first of these involves the combustion of molten phosphorus, sprayed into a mixture of air and steam in a stainless steel chamber. The P4O10 formed initially is converted into H3PO4 ... 

In phosphoric acid production plants, both red shale and fireclay brick have excellent resistance to all concentrations of phosphoric acid at temperatures up to 250°F, provided the acid contains no HF. If HF is present in the phosphoric acid, carbon brick construction must be used. As a rough rule-of-thumb, HF levels above 50 ppm in phosphoric acid require tank linings of carbon brick bonded and jointed with a carbon (or barytes) filled furan mortar over a suitable membrane to match the steel or concrete substrate structure. 

Most companies that use merchant-grade phosphoric acid (0-54-0) for suspensions use a batch ammonia-tion process for the production of base suspensions or NPK mixtures. They neutralize the add with anhydrous ammonia and add dry potash [51. A sketch of a typical batch plant that uses phosphoric acid and ammonia is shown in Figure 10.13. This process indudes a stainless-steel (type 316) mix tank, stainless-steel recirculation pump, and a wooden evaporative cooler. 

One direct use of phosphoric acid is rust removal. In steel production, thick steel slabs must be heated and rolled into thinner ones. During this process, the hot steel is exposed... 

---