Record Display for the EPA National Library Catalog


Main Title Atmospheric Emissions from Wet-Process Phosphoric Acid Manufacture.
CORP Author National Air Pollution Control Administration, Raleigh, N.C.
Year Published 1970
Report Number NAPCA-Pub-AP-57;
Stock Number PB-192 222
Additional Subjects ( Chemical industry ; Air pollution) ; ( Air pollution ; Phosphoric acids) ; ( Fluorides ; Air pollution) ; Ores(Nonmetallic) ; Silicon compounds ; Hydrogen compounds ; Dust ; Sampling ; Spectroscopy ; Silicon tetrafluoride ; Hydrogen fluoride ; Chemical plants ; Scrubbers
Library Call Number Additional Info Location Last
NTIS  PB-192 222 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 98p
Wet-process acid is produced by treating fluorapatite (Ca10(PO4)6F2) or phosphate rock, with sulfuric acid. Phosphate rock must be finely ground to react properly with sulfuric acid, and standard control equipment is normally used to prevent objectionable dust emissions. The emissions of most concern are fluoride compounds liberated from the rock by the sulfuric acid. These consist of hydrogen fluoride, silicon tetrafluoride, and some products of reaction and decomposition of the latter. Most phosphate rock contains 3.5 to 4 percent fluorine, and half of this may be volatilized in the processing. This represents a large potential source of pollution. Because of the principal atmospheric contaminants generated in the process are gaseous fluorides, vapor scrubbing is universally employed to control emissions. Specific devices used for control include venturi scrubbers, impingement scrubbers, and various kinds of spray towers. The results of MCA-PHS stack tests on ten wet-process phosphoric acid plants in various parts of the country are tabulated. The major source of gaseous fluoride emissions in wet-process phosphoric acid plant is the digester. Only trace quantities of particulate fluorides are normally present in exit gases from digesters and filters, and these can be removed effectively by scrubbing. (Author)