Phosphoric acid wet process

Phosphoric acid (wet-process) 28% (20% P20 ), sulfuric acid 20—22%, duoride approx 1—1.5%, probably as hydroduosHicic acid temperature 82—110°C, average 93°C and duration of test 42 days, moderate aeration, agitation by convection only. 

Calcium sulphate in phosphoric acid (wet process for phosphoric acid) Petroleum sulphonate surfactants/hydrocarbon liquid Conditioned in mixer, pellets formed by tumbling... 

Some electric furnace phosphorus is converted directly to phosphorus chemicals, but more than 80% of current production is burnt to the pentoxide which is in turn converted to phosphoric acid. The furnace process has to a large degree been displaced by the phosphoric acid wet process (Chapter 5.2), although it can cope with lower-grade ores than the latter. 

Phosphoric Acid. Wet Process 39 170-183 77-84 - - - 2 percent H.SOi, total fluorides 1.2 percent, gypsum 30 percent... 

Phosphoric Acid. Wet Process 69 490 to 550 254 to 287 B B - - highly concentrated, aerated acid. 69% P-0., static and agitated... 

Phosphoric Acid, Wet Process 93.5 398-410 203-210 - - B - (67.8 percent PtOr,). containing about 4.3 percent sultunc acid and 4.4 percent iron and aluminum... 

Phosphoric Acid, Wet Process 96.6 410 210 - E - G 70% as PA. 35 r ortho. 35% non-ortho sulfuric acid about 4%, hydrofluoric acid about 0.3%. calcium about 0.2%... 

Phosphoric Acid, Wet Process 98 390-460 199-238 - s - - (71% PA), sulfuric acid 4-6%. iron and aluminum 2.8-3.0%aslrioxides, fluorine compounds 0.5-1.0% (calculated as tiuonde). extensive aeration... 

Phosphoric Acid. Wet Process 98 400 204 B B B - ammonium bisulfate 3,8%, hydrofluoric acid 0.4%. 23 days... 

Phosphoric Acid. Wet Process 410 210 U U B U vapor above phosphoric acid 93 5% (67% P O ). containing about 4 3% sulfuric acid and 4 4% Kon and aluminum oxides Fluoride is present betON 1.5%. aeration... 

Phosphoric acid-nitric acid - 647, 738 Phosphoric acid pickling solution - 696 Phosphoric acid scrap liquor - 44, 45 Phosphoric acid slurry - 697 Phosphoric acid-sulfuric acid - 697, 725 Phosphoric acid, wet process - 697, 698 Phosphoric anhydride (see Phosphorus pentoxide) Phosphorous acid - 42, 43, 237, 245, 386, 390, 554,661,795... 

Rider and Amott were able to produce notable improvements in bond durability in comparison with simple abrasion pre-treatments. In some cases, the pretreatment improved joint durability to the level observed with the phosphoric acid anodizing process. The development of aluminum platelet structure in the outer film region combined with the hydrolytic stability of adhesive bonds made to the epoxy silane appear to be critical in developing the bond durability observed. XPS was particularly useful in determining the composition of fracture surfaces after failure as a function of boiling-water treatment time. A key feature of the treatment is that the adherend surface prepared in the boiling water be treated by the silane solution directly afterwards. Given the adherend is still wet before immersion in silane solution, the potential for atmospheric contamination is avoided. Rider and Amott have previously shown that such exposure is detrimental to bond durability. 

White phosphorus also can be produced by a wet process using phosphoric acid, a process that was practiced historically in commercial production. In this method the starting material, phosphoric acid, usually is prepared in large vats by reacting phosphate rock with sulfuric acid ... 

Granular triple super phosphate MAP DAP Power generation Contact process for Sulfuric acid Wet process for phosphoric acid Acetic acid-standard method... 

FIGURE 10.45 Dry-jet wet-spinning process for cellulose solutions in anhydrous phosphoric acid (Akzo process). (From Boerstoel, H., Liquid Crystalline Solutions of Cellulose in Phosphoric Acid for Preparing. Cellulose Yarns, Ph.D. dissertation, University of Groningen, 1998.)... 

There are two basic types of processes for the production of phosphoric acid furnace processes and wet processes. Furnace processes include the blast-furnace process and the electric-furnace process. The blastfurnace process has not been used commercially since 1938. Tlie electric-furnace process is used extensively to make elemental phosphorus, most of which is converted to phosphoric acid for nonfertilizer uses. SirKe it is unlikely that furnace processes wll be competitive for producing phosphoric acid for fertilizer use, except possibly in unusual circumstances, these processes will be described only briefly. 

Wet-Process Phosphoric Acid. As indicated in Figure 7, over 95% of the phosphate fertilizer used in the United States is made by processes that require an initial conversion of all or part of the phosphate ore to phosphoric acid. On a worldwide basis also, the proportion of phosphate fertilizer made with phosphoric acid is very high. Thus processes for production of phosphoric acid are of great importance to the fertilizer industry (see PHOSPHORIC ACID AND THE PHOSPHATES). 

There are numerous variations of the wet process, but all involve an initial step in which the ore is solubilized in sulfuric acid, or, in a few special instances, in some other acid. Because of this requirement for sulfuric acid, it is obvious that sulfur is a raw material of considerable importance to the fertilizer industry. The acid—rock reaction results in formation of phosphoric acid and the precipitation of calcium sulfate. The second principal step in the wet processes is filtration to separate the phosphoric acid from the precipitated calcium sulfate. Wet-process phosphoric acid (WPA) is much less pure than electric furnace acid, but for most fertilizer production the impurities, such as iron, aluminum, and magnesium, are not objectionable and actually contribute to improved physical condition of the finished fertilizer (35). Impurities also furnish some micronutrient fertilizer elements. 

A flow sheet of the basic TVA process for granular diammonium phosphate is given in Figure 12. The raw materials are wet-process phosphoric acid and anhydrous ammonia. Feed acid concentration of at least 40% P2 5 required to give a satisfactory water balance. This average concentration usually is provided by two separate feed streams, one of 54% P2 5 concentration and one of about 30% P2 5 arrangement shown, the 54% acid is... 

Fig. 24. Routes of wet-process phosphoric acid into solution-type and suspension-type mixed fertilizer.

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