The Strength and the High Temperature Behaviors of Self-reducing Pellets Containing EAF Dust.

Abstract

The objective of this work was to study the cold and hot behaviors, that is, cold compressive strength, decrepitation, swelling, compressive strength after heating and efficiency of zinc removal of self-reducing pellets containing coal fines and EAF dust. Pellets with 3 and 5 wt% Portland cement, 12 wt% CaCO 3 and without additive were produced. The effect of binder addition on the cold compressive strength was studied during 28 days. For the study of the high temperature behavior, pellets were submitted to thermal cycles with different heating intensities. The best results of cold compressive strength were obtained with 5 and 3 wt% Portland cement due to hydration of components that are contained in this binder. Pellets with Portland cement (3 and 5 wt%), after drying, did not present decrepitation, showing a correlation between the decrepitation, moisture content and mechanical strength of the pellet. Abnormal swelling was observed in pellets submitted to the thermal cycle with lower heating intensity. Such abnormal swelling was due to the growth of whiskers, and as consequence, it was recorded a maximum swelling (higher than 30 %). With the gasification of carbon promoted by the release of H 2 O (g) and CO 2(g) from the Portland cement and CaCO 3 , it was possible to obtain a higher zinc removal as compared to the value obtained with pellets without additives, mainly at 1 124°C.

Carbothermic reduction of Electric Arc Furnace Dust via thermogravimetry

“…Some of the EAF dust is being disposed of in hazardous waste landfill sites, but because appropriate storage sites are lacking and placed more distant from the generation point, increasing pressure is being placed on steelmakers to adopt some method for the treatment of the dust (Mantovani and Takano, 2000).…”

Reduction Behaviour of Self-reducing Blends of In-plant Fines in Inert Atmosphere

“…In addition, production of DRI by heat treatment might also contribute to significant reduction of Zn, which enables recycling of by-products with low Zn-contents in the blast furnace. [8][9][10][11][12][13] In fact, BOF-sludge and BF-sludge in combination with carbon-containing materials such as BF-dust in agglomerates have not been investigated previously. The possibilities to produce agglomerates with chemical-and physical properties suitable for self-reduction need to be studied.…”

Thermal Strength Characteristics and Mechanism of Iron Ore and Carbon Pellets in the Non-isothermal Reduction Process

“…Qingmin MENG, 1) Rufei WEI, 1) Jiaxin LI, 1,3) Ping WANG, 1) Zhifang GAO, 1,2) Zhanxia DI 1) and Hongming LONG 1,2) * The thermal strength characteristics and mechanism of iron ore and carbon pellets (ICP) in the non-isothermal heating process, including the effect of reducing agent, carbon content and heating rate on the thermal strength, were studied by the on-line test device of thermal strength, combined with the TG/DTG-DTA data, the samples microstructure and porosity after reduction. When ICP was damaged by external force at high temperatures, it existed in two states: crush and plastic deformation.…”

“…Iron ore and carbon pellets (ICP), as a new ironmaking raw materials with good reduction properties, provides some possibilities for the new processes development, such as the production of metallized raw materials, the treatment of steel waste containing Fe and the dressing of complex refractory ore. [1][2][3] Many works have been done referring to the reduction mechanism of ICP [4][5][6][7][8][9][10][11][12][13] and the strength of ICP after reduction, 14,15) providing an important support for the development and application of ICP. Jung et al 4) found the critical temperature of carbon gasification was 1 055°C in the carbothermic reduction of magnetite by TGA-DSC-QMS.…”