Zeolites Synthesized from Class F Fly Ash and Sodium Aluminate Slurry

Abstract

A Class F fly ash was combined with a sodium aluminate slurry (3:1 Na:Al) in an attempt to synthesize zeolites from a highly alkaline waste stream. The reaction was studied as a function of composition (3:2, 1:1, and 1:2 fly ash:slurry), time (1, 3, and 7 days), and temperature (80°, 130°, and 180°C). X-ray diffraction analyses of the products indicated that the fly ash and sodium aluminate had combined to form Zeolite A at 80°C, and NaP1 (a gismondene-type) and an unnamed hydroxysodalite-type at 130°and 180°C. The fact that the pH of the reactants decreased from initial values in excess of 13 to near neutral (7-9) after reaction signifies that the bulk of the sodium had been incorporated into zeolitic phases. Because of the unique adsorptive and cation exchange capabilities of zeolites and the fact that some samples formed reasonably hard monoliths, zeolitic materials formed in this way might make excellent waste forms for ''mixed wastes'' which contain both radioactive and hazardous chemical species.

Silica fume as porogent agent in geo-materials at low temperature

“…In a strong alkaline solution, aluminosilicate reactive materials are rapidly dissolved into solution to form free SiO 4 and AlO 4 tetrahedral units. 2,3 During the polycondensation reaction, the tetrahedral units are linked in an alternate manner to yield amorphous geopolymers. Geopolymer concretes are based on compounds that are generally produced from one or more solid components (binders) and one or more liquid components (activators), which react together to form strong, durable materials.…”

Enhancing the Mechanical and Microstructural Properties of Silica Fume Blended Fly Ash Based Geopolymer Using Murram as a Tertiary Supplement

“…In natural clay material, the approach of aluminosilicate is governed by calcination. Calcination is a thermal healing process in presence of oxygen applied to ores, to bring about a thermal decomposition, phase transition or removal of a volatile fraction 24 . This formation is projected through three steps: firstly; construction of a gas, secondly; improvement in viscous nature thirdly; progressive association.…”

Advanced Cements for Geothermal Wells

“…As already reported [31] and by other investigators [32][33][34][35][36], sodium silicate and NaOH activators were used to stimulate the latent pozzolanic properties of the Class F fly ash that consisted of two major crystalline components, mullite and quartz. In particular, the mullite (3Al 2 O 3 .2SiO 2 ) phase favorably reacted with these activators to form the zeolite phases in the Na 2 O-Al 2 O 3 -SiO 2 -H 2 O system.…”