Experiences of Bio-Coal Applications in the Blast Furnace Process—Opportunities and Limitations

Metal production, and especially iron ore-based steel production, is characterized by high fossil CO2 emissions due of the use of coal and coke in the blast furnace. Steel companies around the world are striving to reduce the CO2 emissions in different ways, e.g., by use of hydrogen in the blast furnace or by production of iron via direct reduction. To partially replace fossil coal and coke with climate neutral bio-coal products that are adapted for use in the metal industry, e.g., at the blast furnace, is a real and important opportunity to significantly lower the climate impact in a short-term perspective. Top-charging of bio-coal directly to the blast furnace is difficult due to its low strength but can be facilitated if bio-coal is added as an ingredient in coke or to the mix when producing residue briquettes. Bio-coal can also be injected into the lower part of the blast furnace and thereby replace a substantial part of the injected pulverized coal. Based on research work within Swerim, where the authors have been involved, this paper will describe the opportunities and limitations of using bio-coal as a replacement for fossil coal as part of coke, as a constituent in residue briquettes, or as replacement of part of the injected pulverized coal. Results from several projects studying these opportunities via technical scale, as well as pilot and industrial scale experiments and modelling will be presented.

Moisture as assessment criterion for coal rank and coal layers hazardous characteristics manifestation

For the time being, moisture effect to the useful quality of coals has been researched comprehensively in detail. Herewith, there are a lot of unsolved problems related to the safety working out of coal layers. Presence of different forms of moisture in fossil coals essentially influences the coal layers hazardous characteristics manifestation during the mining activities. The Article deals with the results of analyses of more than thousand samples of the Donets Basin coals from different deposits, to research the relationship of total moisture and organic matter components in the coal carbonizations during the metamorphic processes. The researches have allowed separation of 3 stages for the fossil coal conversions. It is noted that at the initial stage, the carbon content is about 80%, moisture proportion in carbonization is rather high—0.36; but it decreases abruptly down to 0.12, in case of the carbon content increasing up to 86.5%. And the proportion of components (hydrogen, oxygen, nitrogen, and sulphur) total increases essentially up to 0.88. At the next stage, at 86.5÷91.5%, the components proportion in carbonization changes insignificantly. At the final stage of coal metamorphic conversions, 4-time growth of moisture proportion takes place in carbonization. It is found that moisture proportion in any form to be found in the coals shall be considered as a rank index, which is necessary to determine the coal layers hazardous characteristics.

Specific Features of the Structure of Various Coal Ranks at the Nano Level

Structural factors and functions of radial distribution of atoms of different coal ranks have been calculated by X-ray diffraction analysis. This made it possible to establish that the main structural component is the clusters with graphite-like packing of atoms. The predominant size of these clusters (calculated from the peaks of small-angle X-ray scattering at 5° in CoKα-radiation) for coals with a carbon content of 83--95 % is within 2--3 nm. Fossil coal is an amorphous carbonaceous substance consisting of polymorphic modifications in the sp2- and sp3-states. According to the results obtained using Raman scattering spectroscopy, the physical properties of amorphous natural coals are strongly dependent on the ratio of sp2- and sp3-hybridization of atomic orbitals. Moreover, studies have shown that the carbon atoms of the coal matrix in the sp2-state are represented by both aromatic and aliphatic conjugated chain fragments. It was found that the degree of ordering in rank LF coals is higher than in coals of a higher stage of metamorphism. This is possible if the hydrocarbon matrix in rank LF coals can be represented as a polymer consisting of conjugated chains with periodicity. With an increase in the stage of coal metamorphism, starting with coal rank G, the transformation of the coal structure occurs with a violation of the periodicity of the conjugated fragments of the polymer matrix connecting graphite-like clusters, a decrease in their length, and an increase in randomness in their arrangement

AVALIAÇÃO QUÍMICA DE LENHOS CARBONIZADOS DE Araucaria columnaris SOB DIFERENTES CONCENTRAÇÕES DE OXIGÊNIO COMO COMPARATIVO DE ANÁLISE DE charcoal FÓSSIL

CHEMICAL EVALUATION OF Araucaria columnaris CARBONIZED WOODS UNDER DIVERSE OXYGEN CONCENTRATIONS AS COMPARATIVE ANALYSIS OF FOSSIL charcoal. In the face of environmental changes concerns, the study of climate change becomes essential to understand the life trajectory of planet earth. For this purpose, this work seeks to understand climate change and fluctuations in the amount of atmospheric oxygen across geological ages, carbonizing the Araucaria columnaris wood in varying oxygen concentrations, and comparing them to the fossil coal from Quiteria Outcrop. In this study, pyrolysis of Araucaria columnaris wood occurred with the use of TGA, under an atmosphere of 21% and 30% O2, analyzed in FTIR, distinguishing the constituent compounds of the wood. Multivariate analysis of the mains components (PCA) was applied, for data crossing. There is a distinction between carbonized wood and fossil charcoal, the charcoal burning temperature as well as the atmospheric oxygen composition being inconclusive. However, FTIR results indicate that the amount of oxygen has an influence on the degradation of the wood, and samples at 450 °C have greater similarities with fresh wood. Thus, it was observed that the temperature and the burning time are the main factors of the fires, being that the amount of oxygen available in the atmosphere influences the firing process.

ON THE REPLACEMENT OF FOSSIL COAL IN LOCAL SOLID FUEL BOILERS

The paper substantiates the need to replace fossil coal in local solid fuel boilers by biocoal produced from various types of agricultural waste. Selection of the best available technology for biocoal production should be based on an integrated assessment including economic, environmental and social aspects. It is noted that direct combustion of agricultural waste does not meet environmental safety standards and also requires significant costs for modernization of existing boiler equipment. It is proposed to produce biocoal from agricultural waste using modern methods of thermochemical treatment — torrefaction and carbonization. End-products of biomass torrefaction — biocoal pellets or briquettes — have high calorific value, low sulfur and heavy metal contents, and low nitrogen oxide emissions. Hydrothermal carbonization is currently the most advanced biomass processing technology. It completely prevents pollution and has a number of significant advantages over other methods of biomass treatment. These advantages make it possible to consider hydrothermal carbonization to be the best available technology for the production of biochar, liquid biofuel and other products from non-food biomass. Bibl. 15, Fig. 2, Tab. 1.