Interaction between high-alumina chamotte and orthophosphoric acid

Abstract

Aluminosilicate masses based on a chamotte filler with an addition of orthophosphoric acid or aluminophosphates are used extensively in the form of packing masses, concretes, and gunite masses [1][2][3][4][5][6]. It is known from [7][8] that the interaction between the aluminosilicate chamotte and the orthophosphoric acid occurs only on heating. According to the data in [7], chamotte containing 30.8% of A1203 and 62.8% SiO 2 does not react with orthophosphoric acid below 300~The decomposition of the mullite followed by the formation of A1PO 4 by the action of orthophosphoric acid is established only at 500~ while the crystallization of AlPO4 in the cristobalite form occurs at 1200~ [7]. Zamyatin et al. [9] believe thatthe decomposition of mullite occurs at a significantly lower temperature (150~ with the formation first of monosubstituted acid aluminum phosphate and then at 700-1000~ aluminum orthophosphate is formed.Thus, it follows from the data that the interaction between aluminosilicate chamotte (or more accurately the mullite in the chamotte) and the orthophosphoric acid only occurs with heating; at 150-500~ acid aluminum phosphates are formed and at higher temperatures aluminum orthophosphate is formed. The formation of silicon phosphates is established with the interaction between chamotte and orthophosphoric acid between 300 and 8o0~ [7].The present article reports some results of a study of the processes occurring with the interaction between high-alumina chamotte and orthophosphoric acid. ; 2) combined as phosphate; 3) as monosubstituted aluminum phosphate; 4) as di-substituted aluminum phosphate. Fig. 2. X-ray patterns of a specimen prepared from mixture H after storage for more than 20 days (20-25~ x ) mullite; 9 hydrated aluminum phosphate.