Thermal analysis evaluation of the reactivity of coal mixtures for injection in the blast furnace

Abstract

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

Chars from agricultural wastes as greener fuels for electric arc furnaces

“…The grape seed char proximate analysis shown in this work agrees with analyses of similar residue chars produced under analogous pyrolysis conditions reported elsewhere [32,33]. It is worth mentioning that the total volatile content shown by this char falls within the range used in the steelmaking industry (10-40 wt%) [34]. Moreover, as can be seen in Table 1, ash content of grape seed char was similar to those of Coal B and Coal C. Fig.…”

“…However, ash content is also found to influence the slag foaming behaviour by affecting the rate of CO and CO 2 generation [5,11,15,16,21,23]. Grape seed ash has been reported to contain relatively reactive active salt compounds (K, Ca, Mg) more prone to forming deposits, rather than more stable silicates found in coal ashes, which lowers surface tension and makes it easier for gases to escape [34,39]. Nevertheless, significant thermal similarities between grape seed char and the coals B, C and D have been established, which would show the suitability of this biomass char to partially substitute coal as injection and/or charge carbon materials.…”

Corn Cob as a Potential Feedstock for Slow Pyrolysis of Biomass

“…40 Reactivity is the rate at which the char reacts in an oxidising or reducing atmosphere, while devolatilisation describes the easiness of char reacting with the gasification agent. 52 The reactivity of the corn cob feedstock is reflective in the DTG curves. It is represented by the DTG peak height which is directly proportional to its reactivity.…”

Reactivity of brazilian coal, charcoal, imported coal and blends aiming to their injection into blast furnaces

“…The principal use for the coal mined in Brazil is the combustion for power generation. Studies on the properties of this coal have shown that it could be injected into BFs in blends with imported coals [4][5][6] . Besides coal, another promising fuel in Brazil is biomass.…”