Ecological principles of wet-process phosphoric acid technology

Abstract

Based upon fundamental results obtained for phosphate rock dissolution and calcium sulphate crystallization, the behaviour of both substances inside industrial reactors of wet-process phosphoric acid (WPPA) production is described. This approach results in some new ideas for the ecological production of WPPA. The main feature requires separation of the phosphate rock dissolution from the calcium sulphate crystallization stage. As a result, the optimal chemical, i.e. the acidity level for the dissolution and supersaturation value for crystallization, and hydrodynamic, i.e. high agitation intensity for the dissolution and slow agitation intensity for the crystallization, conditions could be provided. A brief technological scheme for ecologically clean WPPA production technology is also proposed.1998 SCI (

Calcium orthophosphates

“…Manufacturing of elementary phosphorus (white and red), 71 , 72 phosphoric acids, 37 , 73 - 76 various phosphorus-containing chemicals and, especially, agricultural fertilizers (namely, superphosphate, 77 - 79 ammonium orthophosphates 80 ) are the major industrial applications of natural calcium orthophosphates. The annual consumption of a phosphate rock has approached ~150 million tons, and about 95 percent of this production is utilized in the fertilizer industry 81 , 82 …”

Extraction of rare earth elements from waste products of phosphate industry

“…In this regard, apatite ores (Ca10(PO4)6A2 with A = F, OH or Cl), used for the production of phosphate fertilizers or phosphoric acid, have been treated for extraction of REEs as secondary products [20][21][22]. Apatite is an important host mineral for REEs in igneous and metamorphic rocks, with trivalent rare earth cations substituting calcium ions in the apatite lattice structure (with an REEs concentration that can exceed 1g per kg of ore) [23].…”