Extent of zeolite synthesis via alkaline fusion from tailings dam sediments

Author(s)

Dias de Andrade, Fabio Ramos ^[1] ; Akemi Guimaraes Yogi, Maria Thereza ^[1] ; Gomes, Elton Barbosa ^[1] ; Shinzato, Mirian Chieko ^[2]

Affiliation

^[1] Univ Sao Paulo, Inst Geociencias, Rua Lago 562, BR-05508080 Sao Paulo, SP - Brazil

^[2] Univ Fed Sao Paulo, Inst Ciencias Ambientais Quim & Farmaceut, Rua Sao Nicolau 210, BR-09913030 Diadema, SP - Brazil

• Document type: Journal article
• Source: ENVIRONMENTAL EARTH SCIENCES; v. 79, n. 16 AUG 6 2020.
• Web of Science Citations: 0

Abstract

Zeolite was synthesized via alkaline fusion from the tailings dam sediments of a sand mine in southern Brazil. The sediments are composed of a mixture of illite, kaolinite, vermiculite, quartz and K-feldspar yielding a silty-loam texture. The extent of zeolite synthesis was tested under varied NaOH:sediment ratio, temperature and fusion time. At the NaOH:sediment ratio of 8:5 and fusion temperature of 600 degrees C, all minerals were dissolved and converted in faujasite, except a quartz residue of less than 5 wt%. The synthetic faujasite shows intergrown octahedral habit, grain size < 2 mu m, specific surface area of 760 m(2) g(-1)and cation exchange capacity of 4.6 cmol kg(-1). Experiments at lower NaOH:sediment ratio produced lower amounts of zeolite from 6:5 to 5:5 and 4:5, faujasite fraction declined from 73 to 50 wt%. At an NaOH:sediment ratio of 3:5, the faujasite fraction dropped to 0.7 wt%, below which no faujasite was formed. By decreasing temperature from 550 to 250 degrees C, a smooth decrease in faujasite formation was observed, from 64 to 29 wt%. A synthetic analogous of ferrierite appeared in the runs at 300 and 250 degrees C. Experiments using prolonged heating (up to 12 h) at low temperatures (300, 200 degrees C) and low NaOH:sediment ratio (3:5) did not enhance zeolite formation. Kaolinite and vermiculite were dissolved in all runs, while residual illite was ubiquitous and residual quartz was present in all experiments. (AU)

• FAPESP's process: 14/15748-3 - Zeolite synthesis from sedimentation pond residues
• Grantee: Maria Thereza Akemi Guimarães Yogi
• Support Opportunities: Scholarships in Brazil - Scientific Initiation