Análise integrada do resíduo de bauxita e do Combustível Derivado de Resíduos: revisões, caracterização e produção de compósitos para aplicação na indústria cimenteira

Abstract

The aim of this work was to deepen the understanding of bauxite residue (BR) (originating from aluminum production) and Refuse-Derived Fuel (RDF) (originating from municipal and industrial solid waste) in Brazil and worldwide, as well as to produce and evaluate a composite formulated with these materials, capable of acting simultaneously as a fuel and as a clinker component in the cement industry. The work is organized into five chapters. Chapter 1 presents a literature review; Chapters 2 and 3 include systematized quantitative and qualitative literature reviews on BR and RDF; Chapter 4 presents an experimental characterization of RDF; and Chapter 5 covers the production and evaluation of the composite material. The systematized review on BR was based on the analysis of 1,539 scientific articles indexed in the Web of Science database between 1995 and 2024. The main trends and applications of BR were mapped, with emphasis on its use in the production of materials. The analysis also revealed knowledge gaps regarding BR and differences in research between the Brazilian and global contexts. The systematized review on RDF was based on the analysis of 774 articles, 16 of which had Brazilian authorship. The study showed that, although RDF has great potential as an alternative energy source, its properties and regulatory requirements limit broader adoption. It also demonstrated that Brazil needs to advance in the waste-to-energy context, and that RDF in the country is almost exclusively associated with use in cement plants. The characterization of RDF included the following analyses: gravimetric composition, moisture content, volatile matter, ash content, fixed carbon, higher heating value, elemental and mineralogical analyses. The data obtained provided insights into the thermal behavior of RDF, its potential as an alternative fuel, and the challenges of its utilization. Finally, a composite material was developed by combining BR and RDF in different proportions, aiming to produce a solid fuel with dual function: thermal energy generation and use as raw material for clinker. The composite was produced by a thermo-rotational process and evaluated in terms of energy properties and ash composition, with emphasis on the enrichment in metallic oxides provided by the BR, favoring its use in cement kilns. The results indicated that all composites maintained properties compatible with thermal applications and presented an optimized elemental composition for their use as clinker raw material, reinforcing the dual potential: as an alternative fuel and as a mineral input. As a general contribution, this work integrates different approaches to propose viable and sustainable solutions for waste utilization, with potential positive environmental impact and alignment with the Sustainable Development Goals.