Oxidative Leaching of Zinc and Alkalis from Iron Blast Furnace Sludge

The sludge from a wet-off gas cleaning system of the iron blast furnace (BF) contains significant amounts of iron; however, they cannot be recycled due to their high content of zinc and alkalis. These compounds are detrimental to the optimal performance of iron and steelmaking furnaces. In this work, a comparative laboratory study to reduce zinc and alkali contained in the blast furnace sludge (BFS) is presented. The effect of leaching parameters such as oxidant (i.e., ferric ion, oxygen or ozone), aqueous solution media (i.e., 0.2 M NH4Cl, 0.2 M HCl and 0.1 M H2SO4) and temperature (i.e., 27 and 80 °C) on Zn and alkalis (Na2O and K2O) removal were studied by applying an experimental design. The results obtained show that Zn and K2O removal of 85% and 75% were achieved under the following conditions: Ozone as an oxidant agent and 0.1 M H2SO4 as an aqueous medium, temperature had no significant effect. The results are supported by thermodynamic diagrams and the possible chemical reactions are mentioned. Although the results also indicate that leaching under the above conditions dissolves up to 9% of iron, this loss is much less than leaching without the oxidizing conditions generated by the ozone. The BFS obtained from this treatment could be recirculated to the iron or steelmaking processes to recover iron values.

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The adsorption of copper (II) ions from aqueous solution on blast furnace sludge

Journal of Materials Science Letters ◽

10.1007/bf00240790 ◽

1996 ◽

Vol 15 (15) ◽

Cited By ~ 5

Author(s):

F.A. Lopez ◽

C. Perez ◽

A. Lopez-Delgado

Keyword(s):

Aqueous Solution ◽

Blast Furnace ◽

Blast Furnace Sludge

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Removal of Ni2+from aqueous solution by blast furnace sludge as an adsorbent

Desalination and Water Treatment ◽

10.5004/dwt.2010.1580 ◽

2010 ◽

Vol 21 (1-3) ◽

pp. 286-294 ◽

Cited By ~ 7

Author(s):

Ankica Radjenovic ◽

Jadranka Malina ◽

Anita Strkalj

Keyword(s):

Aqueous Solution ◽

Blast Furnace ◽

Blast Furnace Sludge

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Gasification as an optimum alternative for the sludge management

Water Practice & Technology ◽

10.2166/wpt.2011.0080 ◽

2011 ◽

Vol 6 (4) ◽

Cited By ~ 2

Author(s):

C. Peregrina ◽

J. M. Audic ◽

P. Dauthuille

Keyword(s):

Power Generation ◽

Anaerobic Digestion ◽

Sewage Sludge ◽

Combined Heat And Power ◽

Gas Production ◽

Waste Reduction ◽

Fluidised Bed ◽

Sludge Management ◽

Gas Cleaning ◽

Cleaning System

Assimilate sludge to a fuel is not new. Sludge incineration and Combined Heat and Power (CHP) engines powered with sludge-derived anaerobic digestion gas (ADG) are operations widely used. However, they have a room of improvement to reach simultaneously a positive net power generation and a significant level of waste reduction and stabilization. Gasification has been used in other realms for the conversion of any negative-value carbon-based materials, that would otherwise be disposed as waste, to a gaseous product with a usable heating value for power generation . In fact, the produced gas, the so-called synthetic gas (or syngas), could be suitable for combined heat and power motors. Within this framework gasification could be seen as an optimum alternative for the sludge management that would allow the highest waste reduction yield (similar to incineration) with a high power generation. Although gasification remains a promising route for sewage sludge valorisation, campaigns of measurements show that is not a simple operation and there are still several technical issues to resolve before that gasification was considered to be fully applied in the sludge management. Fluidised bed was chosen by certain technology developers because it is an easy and well known process for solid combustion, and very suitable for non-conventional fuels. However, our tests showed a poor reliable process for gasification of sludge giving a low quality gas production with a significant amount of tars to be treated. The cleaning system that was proposed shows a very limited removal performance and difficulties to be operated. Within the sizes of more common WWTP, an alternative solution to the fluidised bed reactor would be the downdraft bed gasifier that was also audited. Most relevant data of this audit suggest that the technology is more adapted to the idea of sludge gasification presented in the beginning of this paper where a maximum waste reduction is achieved with a great electricity generation thanks to the use of a “good” quality syngas in a CHP engine. Audit show also that there is still some work to do in order to push sludge gasification to a more industrial stage. Regardless what solution would be preferred, the resulting gasification system would involve a more complex scenario compared to Anaerobic Digestion and Incineration, characterised by a thermal dryer and gasifier with a complete gas cleaning system. At the end, economics, reliability and mass and energy yields should be carefully analysed in order to set the place that gasification would play in the forthcoming processing of sewage sludge.

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Development of a simplified gas ultracleaning process: experiments in biomass residue-based fixed-bed gasification syngas

Biomass Conversion and Biorefinery ◽

10.1007/s13399-021-01680-x ◽

2021 ◽

Author(s):

Christian Frilund ◽

Esa Kurkela ◽

Ilkka Hiltunen

Keyword(s):

Activated Carbons ◽

Low Cost ◽

Fixed Bed ◽

Carbonyl Sulfide ◽

Gas Analysis ◽

Small Scale ◽

Cleaning Process ◽

Medium Temperature ◽

Gas Cleaning ◽

Adsorption Affinity

AbstractFor the realization of small-scale biomass-to-liquid (BTL) processes, low-cost syngas cleaning remains a major obstacle, and for this reason a simplified gas ultracleaning process is being developed. In this study, a low- to medium-temperature final gas cleaning process based on adsorption and organic solvent-free scrubbing methods was coupled to a pilot-scale staged fixed-bed gasification facility including hot filtration and catalytic reforming steps for extended duration gas cleaning tests for the generation of ultraclean syngas. The final gas cleaning process purified syngas from woody and agricultural biomass origin to a degree suitable for catalytic synthesis. The gas contained up to 3000 ppm of ammonia, 1300 ppm of benzene, 200 ppm of hydrogen sulfide, 10 ppm of carbonyl sulfide, and 5 ppm of hydrogen cyanide. Post-run characterization displayed that the accumulation of impurities on the Cu-based deoxygenation catalyst (TOS 105 h) did not occur, demonstrating that effective main impurity removal was achieved in the first two steps: acidic water scrubbing (AWC) and adsorption by activated carbons (AR). In the final test campaign, a comprehensive multipoint gas analysis confirmed that ammonia was fully removed by the scrubbing step, and benzene and H2S were fully removed by the subsequent activated carbon beds. The activated carbons achieved > 90% removal of up to 100 ppm of COS and 5 ppm of HCN in the syngas. These results provide insights into the adsorption affinity of activated carbons in a complex impurity matrix, which would be arduous to replicate in laboratory conditions.

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