Effect of impurities in wet-process phosphoric acids on DAP grades. [Diammonium phosphate]

Conference · Sat Nov 01 04:00:00 EST 1980

OSTI ID:5483979

Achorn, F P; Dillard, E F; Frazier, A W; Salladay, D G

Results of this study identify the main problems in meeting diammonium phosphate (DAP) grade specifications and suggest some possible solutions to these problems as follows: 1. The major source of grade deficiency in the commercial samples which were investigated was calcium. Some solutions to this problem are to maintain filter cloths in the phosphoric acid unit in good condition, operate the phosphoric acid unit at as low an acid temperature as consistent with good operation of this unit, and partially clarify the acid before it is used. 2. In the DAP unit the amount of Fe/sub 2/O/sub 3/ and F in the acid affects the content of C.I. P/sub 2/O/sub 5/ in the product. If the F:Fe/sub 2/O/sub 3/ wt ratio in the product can be kept above 2.3:1, probably the C.I.-P/sub 2/O/sub 5/ content of the product will be less than 0.1 percent. At lower F:Fe/sub 2/O/sub 3/ wt ratios, it is advantageous to have low retention times in the preneutralizer and ammoniator-granulator when the N:P mole ratio is 1.4:1 or higher. 3. Other data show that the N:P mole ratio in the slurry from the preneutralizer to the granulator must be above 1.4:1 to avoid nitrogen deficiencies. At lower ratios the product will contain some MAP; this causes nitrogen deficiency in the products. 4. The Mg and Al contents of the acids have less effect on grade deficiency than Ca and Fe. 5. To avoid highly viscous preneutralizer slurries when low preneutralizer retention times are used, ensure that there is sufficient F available (F:Fe/sub 2/O/sub 3/ wt ratio > 2.0:1) to combine with the Fe/sub 2/O/sub 3/ to form coarse crystals. An alternative to this latter suggestion is to replace the preneutralizer with a TVA pipe reactor which is partially installed in the granulator and discharges viscous slurry directly onto the bed of material in the granulator.

• Research Organization: Tennessee Valley Authority, Muscle Shoals, AL (USA)
• OSTI ID: 5483979
• Report Number(s): TVA/PUB-82/7; CONF-8011147-1; ON: DE82901247
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
320303* -- Energy Conservation
Consumption
& Utilization-- Industrial & Agricultural Processes-- Equipment & Processes
ALKALINE EARTH METALS
AMMONIUM COMPOUNDS
AMMONIUM PHOSPHATES
CALCIUM
CHALCOGENIDES
CONTROL
ELEMENTS
FERTILIZER INDUSTRY
FILTERS
FLUORINE
HALOGENS
IMPURITIES
INDUSTRY
IRON COMPOUNDS
IRON OXIDES
METALS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
PRODUCTION
QUALITY CONTROL
RECOMMENDATIONS
SPECIFICATIONS
TRANSITION ELEMENT COMPOUNDS