Análise de resíduos industriais utilizados na produção de blends para o coprocessamento : uma visão sob o ponto de vista energético

Abstract

Due to the oil crisis in the 1970s, the cement industry, which used fossil fuels, began to turn its attention to the use of alternative fuels derived from industrial waste. In Brazil, this movement began in the 1990s. Between 1997 and 2000, it was seen that the use of alternative fuel averaged 10%, with a maximum of 18%. The practice of using waste as an alternative fuel is known as co-processing. Due to the variety of residues that can be used, they need to be processed beforehand, to obtain a uniform material and a more stable burning. The process of preparing these residues consists of mixing, crushing, and grinding the residues with the final material, also called the blend of waste. The cement industry has discovered over the years that using blends as an alternative fuel and waste co-processing activities has benefits such as lower fuel costs, lower polluting gas emissions, and lower thermal energy consumption in the clinker formation process, and in some cases presents itself as a more environmentally appropriate technology. On the other hand, some environmentalists and researchers in the area show some dissatisfaction with some co-processing practices. The current scenario of co-processing in Brazil has 38 licensed plants. The use of alternative fuels has gained strength, and with that it has come a reduction in the use of fossil fuels. In 2016, the use of alternative fuels was 15.10%. In 2020, it was 28%, exceeding the projection made for the year, which was 23%. For the year 2030, the projection is 35%. The objective of the Brazilian cement industry is to reach 45% by 2050. The first law on co-processing in Brazil was published in 1999. Given the co-processing scenario and its advances, it was replaced after more than 20 years. The new law makes changes such as increasing the amount of waste that can be co-processed, allowing the use of waste with no energy value if environmental gains are demonstrated, requiring waste use approval from the health service, and removing the section on waste mixing and preconditioning units. Given the advances in the use of waste as an alternative fuel, it was proposed to analyze the waste used to formulate the blends in Company A from January to December 2020. The first analysis consisted of the gravimetric determination of waste. After that, the 10 residues with the highest mass were selected each month to estimate the calorific value of the blend produced in company A. The analysis found that the blend of company A could range from 3,288.59 kcal/kg to 4,927.20 kcal/kg. The most used were acid residue sludge, sludge from effluent treatment plants, and contaminated oils. About the use of waste, a considerable change between their sides reported since the beginning of the technique has not been observed, according to the studied company. In general, they are petrochemical, steel, ETP, and various contaminated material residues.