Neutralisation of acid effluent from steel manufacturing industry and removal of metals using an integrated electric arc furnace dust slag/lime process

Abstract

In this study, an integrated electric arc furnace (EAF) dust slag/lime (Ca(OH) 2) treatment method was used to treat acid effluent generated by the same stainless steel producer. EAF slag alone was able to raise the pH to 8.7; thereafter, lime was added to increase the pH to the target pH of 12. The test proved that EAF dust slag, in conjunction with lime, can be used for neutralisation of acid effluent from a steel industry and for the removal of metals Co, Cr, Fe, Ni and Zn. The target metals were removed from the effluent, achieving greater than 99.6% removal. The process was simple and involves only mechanical mixing of the two constituents. Hence, it can be regarded as economically advantageous and environmental friendly since it only utilises a material considered as waste and a small quantity of lime. In addition to being a costeffective replacement for expensive chemicals used in wastewater treatments, this method can alleviate the problem associated with the disposal of slag, a solid waste generated by a steel manufacturing industry.

Treatment of Integrated Steel Plant Wastewater Using Conventional and Advanced Techniques

“…Metals including Zn, Ni, Fe, Cr, and Co were removed using dust slag with removal efficiency higher than 99.6%. [ 83 ]…”

Decarbonising the lime industry: State-of-the-art

“…Quicklime reacts spontaneously with water, and its transport requires strict safety measures, given the strong exothermicity of its hydration reaction (1.14 MJ released per kg of CaO hydrated [3]). Outside the cement industry, a significant portion of CaO (around 27% in the EU in 2017 [4]) would be hydrated and stored as Ca (OH) 2 , finding application in a wide range of industries, such as: iron and steel manufacturing for the treatment of the acid effluents and heavy metals removal [5], construction [6], soil stabilisation [7], removal of contaminants (e.g. As, F) from potable water [8], low-temperature desulfurization [9] and sulfur scrubbing [10], CO 2 capture [11], wastewater treatment [12], bulk chemicals [13], pharmaceuticals, and cosmetics.…”

Neutralization of Acidic Wastewater from a Steel Plant by Using CaO-Containing Waste Materials from Pulp and Paper Industries

“…The pH is a major factor in neutralization and metal removal through precipitation. The metals form insoluble hydroxides at higher pH, which may be removed from the wastewater to the sediments [ 3 ]. A pH range of 8.0–11.0 minimizes the solubilities of metal hydroxides [ 4 ].…”