Eduardo Osório

Reactivity of Brazilian Coal, Charcoal, Imported Coal and Blends Aiming to Their Injection into Blast Furnaces

For about 10 years the steel industry in Brazil has used pulverized coal injection (PCI) technology in the blast furnaces based on imported coals. In order to decrease the dependence on imported coals, Brazilian coal, which has limited use due to high ash content, was suggested to be mixed with imported coal and charcoal. The aim was to examine the reactivity of the samples. The charcoal use in the steel industry contributes to the CO 2 emission reduction, since it represents a renewable source of energy. The reactivity of the coals, charcoal and mixtures was evaluated through simultaneous thermal analyses. Results of this study are presented and discussed.

Thermal Analysis Evaluation of the Reactivity of Coal Mixtures for Injection in the Blast Furnace

Pulverized Coal Injection (PCI) is an important standard technology replacing coke partially by pulverized coal into the blast furnace that allows a significant reduction of hot metal costs and environmental impact, contributing to a decrease of coke requirements for ironmaking. Coals typically used in this process in Brazil are, at current time, exclusively imported from many countries, although economic important coal-measures occur in the southern part of the country. The Brazilian coals have a low rank, higher contents of inert components, proportioning nocoking properties and an expected high reactivity. Due to these caractheristics, these coals could be used for injection in the blast furnaces in order to decrease the dependency on high cost imported coals. The efficiency in the combustion and the coal reactivity are considered important parameters in the blast furnace, since a larger amount of char (unburned coal) causes severe problems to the furnace operation. The aim of the present work is to compare the reactivity of a south Brazilian coal, obtained from Faxinal mine, with two imported coals and the blends of the Brazilian coal with the imported ones. The reactivity of these coals and their blends were evaluated in a thermogravimetric analyzer. In the experiments, various mass ratios of Faxinal coal and the imported coals were used to compose the blends. The gasification reaction with pure CO2 was conducted under isothermal conditions at 1050 °C and atmospheric pressure. The experimental results show the greater reactivity of the Faxinal coal. The additive behavior was confirmed. The blends with a composition of up to 50% Faxinal coal have parameters according to the usual limits used for PCI.

Review of the rice production cycle: By-products and the main applications focusing on rice husk combustion and ash recycling:

One of the consequences of industrial food production activities is the generation of high volumes of waste, whose disposal can be problematic, since it occupies large spaces, and when poorly managed can pose environmental and health risks for the population. The rice industry is an important activity and generates large quantities of waste. The main solid wastes generated in the rice production cycle include straw, husk, ash, bran and broken rice. As such, the aim of this article is to present a review of this cycle, the waste generated and the identification of opportunities to use them. Owing to impacts that can be minimised with the application of rice husk ash as a by-product, this work is focused on the recycling of the main wastes. In order to achieve that, we performed theoretical research about the rice production cycle and its wastes. The findings point to the existence of an environmentally suitable use for all wastes from the rice production cycle. As rice, bran and broken rice have their main use in the food industry, the other wastes are highly studied in order to find solutions instead of landfilling. Straw can be used for burning or animal feeding. The husk can be used for poultry farming, composting or burning. In the case of burning, it has been used as biomass to power reactors to generate thermal or electrical energy. This process generates rice husk ash, which shows potential to be used as a by-product in many different applications, but not yet consolidated.

Behaviour of coal ashes for pulverised coal injection at high temperatures in relation to their chemical and mineralogical composition - experimental and computational analysis

Abstract The selection of coals for pulverised coal injection usually consists of evaluating the carbonaceous matter. However, the reduction of permeability in the lower section of the blast furnace with high rates of pulverised coal injection can be associated with remaining ashes from the coal combustion process. The aim of this work is to evaluate the behaviour of coal ashes at high temperatures in relation to their chemical and mineralogical composition. These ashes were submitted to the following analysis: chemical (X-ray fluorescence), mineralogical (X-ray diffraction), fusibility (heating microscopy) and viscosity (rotational viscometer). The software FactSage was also used to evaluate the behaviour of coal ashes. It was observed that samples present different chemical and mineralogical compositions, reflecting in the fusibility and viscosity of ashes. Their proportions and relevant phases were determined by computational thermodynamics and also related to the experimental work.

Combustibility and reactivity of coal blends and charcoal fines aiming use in ironmaking

Charcoal is a very important reducing agent in Brazil, the world’s largest steel industry based on charcoal blast furnace. Charcoal generates large amounts of charcoal fines during its production and processing. A good alternative for harnessing this fuel is the injection into coke-based blast furnaces via PCI process (Pulverized Coal Injection), a key technology for reducing use of coke in ironmaking. This study aimed to evaluate the combustibility and reactivity to CO2 of binary blends of charcoal fines and coals with purpose to PCI. Moreover, it was also attempted to identify the reasons for the different behavior of coals. The work was carried out by thermogravimetric analysis (TGA). The proportions of charcoal used were 10, 20 and 50% in mass. Charcoal showed the highest combustibility and reactivity among tested fuels and the blends formulated had higher combustibility and reactivity than single coals.

Carbothermic reduction of Electric Arc Furnace Dust via thermogravimetry

Electric Arc Furnace Dust (EAFD) is a solid waste originated from electric steelmaking furnaces. Currently, according to some authors, there is an estimated generation of 15 to 25 kg of dust per ton of steel produced. The formation of the dust is related to the following steps of the process: furnace charge, metal volatilization, iron vaporization under the arc, drag of solid particles and, mainly by the collapse of CO bubbles from metallic bath decarburation. The dust has metals that are harmful to the environment. Otherwise, it is mostly composed of the elements iron, zinc and oxygen. Due to increasing costs for disposal and because it is considered a hazardous waste, industry is looking at the possibility of returning the dust to the steelmaking process. One of the alternatives is by reintroducing the waste in an electric melting shop using self-reducing agglomerates as part of the furnace burden. In this study, self-reducing mixtures are prepared with EAFD and petroleum coke (PET), presenting chemical and physical characterizations. An evaluation about the behavior of the mixtures is carried out in thermobalance, regarding the possibility of use in measuring accurate PET content in self-reducing pellets. As results it could be stated that the elements of economic interest, Zn and Fe, represent, respectively, 34.23 and 22.80%, in weight. These elements are present in chemical species frankilinite, zincite and magnetite and the reducible oxygen was estimated as 17.90%. Also, it was concluded the optimal content of petroleum coke in the mixtures varies from 10 to 15%, in weight. Therefore, the utilization potential of the thermogravimetric technique in the industrial field for adjustment of carbon content in batches of self-reducing pellets is satisfactory.

Critical analysis of non-isothermal kinetics of poultry litter pyrolysis

Poultry litter is a waste from poultry industry that has been used for bioenergy generation and has high potential as feedstock for thermochemical processes, as pyrolysis. Kinetic parameters of poultry litter pyrolysis are paramount for techno-economic analysis of commercial scale processes. Scientific community has shown concern about the suitable application of different methods (model-free/model-fitting) for the determination of kinetic parameters. The application of an unsuitable method may lead to unreliable kinetic parameters. In this study, the performance of model-free methods for the determination of the kinetic parameters of poultry litter pyrolysis was evaluated. The characterization was performed through thermogravimetric analysis. Were applied the methods of Kissinger–Akahira–Sunose, Flynn–Wall–Ozawa and Vyazovkin. The model-free methods were not adequate to describe the kinetics of poultry litter pyrolysis throughout the whole reaction. Therefore, a model-based (five pseudo-components model) method was applied to obtain the kinetic parameters of poultry litter pyrolysis. Such model provided an adequate fit to the experimental data.

O Simulador da zona de combustão do alto-forno do Laboratório de Siderurgia da UFRGS - uma nova ferramenta na seleção de carvões para injeção

Blast furnace (BF) is the main route for pig iron production. One of the biggest challenges in BF steel industry is the reduction of coke consumption. Cokemaking process employs high cost coals and accounts for the most of polluting gas emissions from integrated steel mills. A successful strategy for saving coke is the injection of auxiliary fuels in tuyere region of BF through PCI (Pulverized Coal Injection) process. Fuel combustion generates energy and reducing gases for iron ore. When injected, coal is subjected to drastic conditions in the raceway of blast furnace: temperatures around 2400 K, heating rates in order of 10 5 to 10 6 K/s and residence times of 10 to 40 ms. Therefore total combustion of coal, especially at high injection rates, is unlikely. It is fundamental to select coals for PCI with good combustibility, thus minimizing the generation of residual solid (char), which can damage the BF operation. There are several types of reactors for the evaluation of coal combustion, such as thermobalances, drop tube furnaces and PCI test rigs. Thermobalances are fixed-bed reactors operating at low heating rates and drop tube furnaces are more suitable for boiler simulation and evaluation of single coals. For operational, strategic and logistical reasons steel mills use coal blends of different characteristics for PCI. Nowadays PCI test rigs are the best option of reactors for evaluation of coals and other fuels for injection. In this context, the Iron and Steelmaking Laboratory of the Federal University of Rio Grande do Sul (LaSid-UFRGS) designed and developed a PCI test rig with innovative features, such as collection of char, quantitative analysis of combustion gases by gas chromatography and acquisition of temperature and pressure data by ultrafast sensors. Unlike the existing models, the equipment is fully automated, being the only one in the country in vertical arrangement, minimizing pressure loss and allowing operation with greater stability. The present work aims to present the characteristics of the LaSid-UFRGS PCI test rig and preliminary experimental results. Key-Words: Ironmaking. Blast furnace. Raceway. Fuels. Pulverized coal. V CONGRESSO BRASILEIRO DE CARVÃO MINERAL CRICIÚMA SC – BRASIL 29 DE MAIO A 01 DE JUNHO DE 2017

AVALIAÇÃO DO EFEITO DA ADIÇÃO DE COQUE DE PETRÓLEO EM TERMOPLASTICIDADE DE MISTURAS DE CARVÕES CONTENDO CARVÃO NACIONAL

Resumo Esse trabalho teve como objetivo avaliar o efeito da adição de diferentes teores de coque verde de petróleo (5, 15 e 30%) nas propriedades termoplásticas de misturas de carvões contendo carvão nacional da camada barro branco. A caracterização termoplástica das misturas foi realizada a partir de testes de plastometria Gieseler e dilatometria AudibertArnu. A caracterização dos carvões mostrou que o carvão nacional possui propriedades termoplásticas muito superiores aos demais carvões. Por consequência, verifica-se que a sua introdução nas misturas causa aumento das propriedades termoplásticas nos testes de plastometria e dilatometria. O coque verde de petróleo, em contrapartida, é um aditivo inerte e atua como um depressor das propriedades termoplásticas. Constatou-se que a adição do coque verde de petróleo às misturas causa redução da fluidez, do intervalo plástico e dilatação nos testes realizados. A sinergia entre do carvão nacional de alta fluidez e o caráter inerte do coque de petróleo mostrou-se vantajoso. Palavras-chave: Termoplasticidade; Carvão Nacional; Coque verde de petróleo; Plastometria Gieseler; Dilatomeria Audibert-Arnu.