Prospects for using boron in metallurgy. Report 1

Abstract

On the basis of literature and our own data, the effect of boron on characteristics of all stages of metallurgical processes (from sintering, smelting of cast iron and ferroalloys, to steel production) and on the properties of the resulting slag and metal was studied. To intensify the pellets hardening at the stage of liquid-phase sintering and to improve their metallurgical properties, it is sufficient to have 0.20 – 0.35 % of boron oxide in them. According to the laboratory studies, the presence of boron oxide in pellets increases their compressive strength by 1.5 – 1.7 times and hot strength by 3 – 4 times. While studying the mechanism and kinetics of sulfur removal, it was shown that the presence of boric anhydride significantly intensifies processes of pellets desulfurization. Their intensive progress goes to the zones of lower temperatures of 1050 – 1100 °С. To increase the sinter strength characteristics, it is possible to add B2O3 to the charge. The introduction of 0.44 % of B2O3 does not affect the sinter abrasion. The content of fines (0 – 5 mm) in comparison with the base sample is reduced by 1.5 times. The use of boron pellets in blast-furnace smelting makes it possible to increase the basicity of the final slag from 1.10 to 1.16. In this regard, the sulfur distribution coefficient increases from 48 to 74. The sulfur content in cast iron decreases by 0.005 %. The possibility of using boron and its compounds to improve the technical and economic indicators of production and the quality of pellets, sinter and cast iron is shown on the base of the presented theoretical, laboratory-experimental and industrial data.

Bonding Mechanism and Process Characteristics of Special Polymers Applied in Pelletizing Binders

“…Calcined colemanite and boric acid are important boron-containing compounds, and their application can significantly improve the strength of preheated and fired pellets [46][47][48]. Calcined colemanite and boric acid contain a large amount of boron oxide (B 2 O 3 ), which has a low melting temperature and can produce a relatively large amount of liquid phase at a lower temperature, promoting the generation of silicate liquid phase [49,50], and thus reducing the liquid phase viscosity and porosity, enhancing the bonding between mineral particles and facilitating the diffusion of solid phase mass points, promoting Fe 2 O 3 recrystallization and significantly improving the fired pellet strength [51,52]. Sivrikaya and Arol [44] combined 0.1 wt.% CMC with 0~1 wt.% calcined colemanite and the fired pellet strength was significantly improved without a significant negative effect on the green pellet strength.…”

Research for Industrial Application of Bentonite-Polymer Material in Ferrous Metallurgy

“…Studies conducted with various mono-materials have shown that, most often, materials with excellent binding ability (organic) do not participate in thermal strengthening in any way. And vice versa-inorganic materials (e.g., colemanite, which, due to its property of reducing the sintering temperature, has found popularity among researchers [17]) practically do not contribute to the clumping of raw pellets but significantly intensify the sintering process. This reasoning in itself suggests that the most rational approach to solving the binder problem can be the study of combinations of binders and strengthening materials and, in the best case, achieving a synergistic effect from the interaction of the inorganic and organic parts of the composite material.…”