Sintering of sepiolite-rich by-products for the manufacture of lightweight aggregates: technological properties, thermal behavior and mineralogical changes

J M Moreno-Maroto,C Martínez-García,B González-Corrochano,J Alonso-Azcárate

doi:10.3989/mc.2021.05620

J M Moreno-Maroto, C Martínez-García + Show 2 more

Open Access

https://doi.org/10.3989/mc.2021.05620

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Abstract

A sepiolite mining by-product (SEP) has been studied as major component for lightweight aggregate (LWA) manufacture. Pellet bursting during firing was avoided by the addition of 2.5 wt% of thermoplastic waste (P) and 2.5 wt% P + 2.5 wt% carbon fiber residue (FC) in powder form. The mixtures were pelletized and then sintered at 1225º˚C for 4 minutes in a rotary kiln. Highly porous white LWAs with good mechanical strength were produced. A mineralogical study revealed the formation of amorphous phase ( > 50%) and minor proportions of enstatite, protoenstatite and diopside. Quartz was the only inherited mineral, appearing in the form of isolated phenocrysts within a general porphyritic texture. The result of this study suggests the promising use of sepiolite (whether or not in residue form) for the manufacture of high quality LWAs.

Highlights

RESUMEN: Sinterización de subproductos ricos en sepiolita para la fabricación de áridos ligeros: propiedades tecnológicas, comportamiento térmico y cambios mineralógicos
In a more recent study, a similar criterion has been followed in the manufacture of lightweight aggregate (LWA) from wastes contaminated with heavy metals, again demonstrating the suitability of sepiolite rejects as a binder even in low proportions [11]
Its composition and particle size is theoretically inadequate according to the Riley [24] and Cougny [46] diagrams, the sepioliterich by-product under study has been demonstrated to have a great potential to be artificially sintered into LWAs in practice

Summary

Introduction

RESUMEN: Sinterización de subproductos ricos en sepiolita para la fabricación de áridos ligeros: propiedades tecnológicas, comportamiento térmico y cambios mineralógicos. Los resultados obtenidos sugieren que la sepiolita (ya sea en forma de residuo o no) puede tener un uso prometedor en la fabricación de LWAs de alta calidad. It has been possible to sinter cordierite-based ceramics, whose industrial application is widespread in several sectors, from sepiolite at temperatures in the range 1200-1300 ̊C [6, 7]. LWAs are granular materials of high porosity, low density and good mechanical strength that are generally sintered by thermal shock, unlike the gradual heating conducted on traditional ceramics. Because of their properties, LWAs are very interesting to be applied in concrete production, in the agricultural sector and/or in civil and environmental engineering. In a more recent study, a similar criterion has been followed in the manufacture of LWAs from wastes contaminated with heavy metals, again demonstrating the suitability of sepiolite rejects as a binder even in low proportions [11]

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