Rejeitos de fundição: recuperação de argila e modificação para aplicações ambientais

Abstract

The iron foundry industry in Brazil generates about 2 million ton of waste per year. The big amount of waste generated has motivated researchers to find destinations for this waste. In this work were investigated different ways to transform foundry sand waste to environmental applications.Chapter 1 provides a general introduction on the foundry production process and a literature review, reporting the most important studies using the waste sand of foundries (WFS). The waste sand and muds characterization are shown in Chapter 2. Moreover, the characterization of raw is shown too. In Chapter 3 were done recovery studies of bentonite clay from mud waste. Through the adjustment of separation parameters such as pH, temperature and time was possible to obtain clay with high levels of purity. In Chapter 4, the waste sand was modified to be used in environmental applications, i.e. the Fenton reaction and Cr(VI) reduction. The WFS was separated into non magnetic and magnetic fractions. The magnetic part was modified by the addition of hematite and carbon, followed by thermal treatment. The materials modified by the addition of hematite and carbon treated at 800 º C showed high activity withconversion of 100% in Cr (VI) reduction. In the reactions of peroxide decomposition and Fenton, the most active systems were obtained by addition of hematite and treated at 800 º C with mineralization of about 70% of organic matter present in the dye indigo carmine.