Search

ABSTRACTUtilisation of by-products of an integrated steel plant improves productivity with diverse mix of raw materials used for iron making. The strength of a briquette made with Blast furnace flue dust and iron oxide with fly ash as a binder depends upon the briquetting pressure, particle size of fly ash, fly ash quantity, and curing temperature. In this study, the effect of process variables on the strength was investigated with ANOVA. The correlation between the process parameters and the strength was examined experimentally and RSM-based optimisation was performed during the preparation of briquettes. The RSM provided optimisation with a confidence level of 95% using the CCD design. This paper demonstrates the correlation between applied pressure, particle size, fly ash quantity, and curing temperature. The developed mathematical model would help in predicting the variation in the compressive strength with the change in the level of different parameters. This model can be useful for setting the optimum value of the parameters for achieving the target compressive strength.

ABSTRACT Synthetic resin flooring has been used since the early sixties, usually installed in commercial, industrial, healthcare and educational buildings because of its hardwearing nature and versatility as a seamless [...]

Blast furnace flue dust and thermal plant generated fly ash are major solid wastes coming from the two important industrial sectors. Flue dust mainly contains iron oxide and carbon. The fly ash contains mostly silica, alumina and iron oxide with small amount of lime. These materials are commonly used in making of bricks and tiles. Little amount of flue dust is used in charge material preparation for iron extraction. In this present study, fixed quantities of blast furnace flue dust (30 wt %) and pure iron oxide fines (65 wt %) are mixed with different binders such as bentonite, lime, sodium silicate, fly ash, starch, molasses, pitch and dextrin. The strength of composite briquettes was determined at green, dry and cured conditions. Moreover, the effect of the variation of fly ash quantity, fly ash particle size, briquetting pressure and curing temperature on the compressive strength of composite briquettes were also investigated. The optimized fly ash quantity of 5 wt%, fly ash particle size of 75 µm (200 mesh), briquetting pressure of 95 MPa and curing temperature of 300 °C provide maximum strength to the briquettes. The phase analysis through XRD and morphology analysis through FESEM-EDS of fly ash added cured composite briquettes were performed.

Wire arc additive manufacturing (WAAM) can create massive metallic components with high deposition rate. The high deposition rate is coupled with heat accumulation in the deposit caused due to repeated heating. Further, the heat accumulation promotes grain growth and deteriorates the mechanical properties of the deposit. Therefore, the objective of the research is to minimize the heat accumulation in the deposit. In this study, the gas tungsten arc welding-based WAAM technique is used to create 40-layered deposit of 2319 aluminum alloy in air- and water-cooled condition. The effect of cooling and remelting is investigated. Under similar processing conditions, the water-cooled deposit is comprised of finer grains compared to the air-cooled deposit. Remelting favors grain refinement of the top region of the deposit. Under tensile loading conditions, the water-cooled deposit performs better with an ultimate tensile strength of 268 ± 5 MPa.

Products developed through the powder metallurgy route have significantly contributed to structural application, automotive, and aircraft industry in the last decades. Several research works are available on the use of pure metal powder for the development of useful products through the powder metallurgy process. The study on the physical and mechanical properties of compacted reduced composite fines produced after crushing of reduced composite briquette containing Blast furnace flue dust, iron oxide, graphite powder, and fly ash is limited. The physical property such as density of green briquettes made with reduced composite fines, and 0.5% sodium silicate has been measured as a function of compaction pressures (75, 90, and 100 MPa). The maximum density of 5341.6 kg/m3was achieved at 100 MPa pressure. The samples possessing maximum density has been sintered at different temperatures of 1100 °C, 1150 °C, and 1200 °C for 60 min, 90 min, and 120 min respectively. The density, compressive strength, and hardness were measured after sintering of the samples. The samples were sintered at 1150 °C for 120 min achieve maximum density of 6111.4 kg/m3, compressive strength of 238.72 MPa, and hardness of 109.34 VHN.

In this study, the extrusion of reduced blast furnace composite fines at elevated temperatures allows manufacturing final products with distinctive microstructure and mechanical properties. The experimental results of extrusion of the composite powder under different laboratory conditions are presented and analysed. The main objective of the study is to demonstrate that blast furnace flue dust fines can be consolidated to highly dense products through extrusion. Reduced blast furnace flue dust and iron oxide fines were compacted at 100 MPa pressure to produce 20 mm and 40 mm diameter and height, respectively, and these compacted materials were subjected to different thermal treatment temperature, namely 1100 °C and 1200 °C, respectively. The product after heat treatment was extruded by direct extrusion process at different pressures such as 175 MPa and 240 MPa, respectively, at both the temperatures. The mechanical properties such as density, compressive strength, hardness and microstructure of the final product have been reported. Quantitative and qualitative metallography has been applied within the extruded product to match with the values of the mechanical properties. The product achieves maximum density of 7.55 gm/cc after extrusion with 240 MPa extrusion pressure at 1200 °C. Furthermore, the maximum compressive strength and hardness values are 336.67 MPa and 117.42HV20, respectively, when the extrusion pressure was maintained at 240 MPa and heat treated at 1200 °C.

Today’s world has experienced the change in the extraction of metal from its native ore to that from secondary resources. The ash and tailings are such secondary resources for extraction of aluminium. The present investigation shows the effect of furnace lining materials and plasma gas on the extraction of aluminium from the waste material during smelting reduction studies. A laboratory scale plasma arc furnace was used for the reduction studies of bottom ash, iron ore slime with charcoal. Experiments in hydrogen and nitrogen plasma environments were carried out inside magnesite and graphite crucible separately. The rate of reduced metal absorption by the liquid metal bath for a fixed time was determined. The output of aluminium through metal, slag and exit gas was calculated to establish a tentative mechanism of smelting reduction. Combination of nitrogen plasma and graphite crucible showed the optimum recovery level of reduced aluminium in metal. The high-temperature plasma could reduce highly stable oxides of waste materials, and the recovery of volatile aluminium in metal could be possible by using a metal solvent bath.

At present various naturally available minerals containing MgO viz. olivine, pyroxenite, dunite, dolomite etc. are widely used in different plants to reduce RDI of iron ore pellets and improve other properties. However, properties of each of the above fluxes are physically and chemically different and they contain different types and quantities of gangue materials, such as silica, alumina (Al2O3), CaO etc. Although, MgO has some specific roles, other gangue materials carried by MgO bearing fluxes also have a significant effect on phase formation or slag bonding in pellet and pellet properties. Thus, different MgO bearing fluxes show different behavior in pellets. It is very imperative to study the actual role of MgO and the effect of different gangue materials in it. This study has examined the actual role of MgO and its optimum requirement as well as the effect of other gangue materials in MgO bearing fluxes. For this purpose, pure MgO, olivine and waste magnesite brick powder have been used separately in pellet making with a high Al2O3hematite ore and their characteristics have been compared. It has been found that 0.9 % pure MgO in pellet can reduce the reduction degradation index to as low as 7.5 %, but it shows a little deterioration in strength property. Other two fluxes provide good strength properties at lower induration temperature but, cannot reduce degradation index to sufficiently low level. Olivine has shown better performance than magnesite because of its different gangue content.