Project & Plant Management, Energy & Utilities and Environmental Technologies
In steel production, wastewater is constantly generated in various unit processes. The wastewater must be treated before the water can be reused internally or released to the environment. Existing wastewater treatment technologies are clean water–oriented, but solid wastes collected in the wastewater treatment processes are generally notorious nuisances that are dirty, full of contaminants and sometimes hazardous. Sustainable recycling of the wastewater treatment solid wastes requires effective separation of beneficial components from undesirable ones. In-process dynamic separation has recently emerged as a promising technology for producing clean, dry and recyclable solid co-products in economic ways while wastewater is being cleaned. ArcelorMittal Global R&D has studied this technology for significantly enhancing recyclability of steel manufacturing wastewater treatment solid wastes.
An important part of the hot rolling process is the reheating of steel products to target temperature using the combustion of natural gas in a furnace. To increase energy efficiency of this reheating process, oxygen enrichment can be used with high entrainment of reaction product gases to distribute the combustion reaction area. The modeling of various configurations was undertaken using computational fluid dynamics to use oxygen enrichment or oxy-fuel in order to avoid changes in the furnace zone temperatures while reducing fuel usage. Effects on the combustion, temperature distribution, species and heat transfer to the steel product are under study.
In the electric arc furnace (EAF) steelmaking industry, dust treatment is one of the most serious issues due to its high costs and environmental burden, and thus this critical problem must be solved for the sustainability of the steel industry. A bench-scale investigation has been conducted in which CaO- and coal-added EAF dust was heated at around 1,000°C to convert ZnFe2O4 into ZnO and Ca2Fe2O5, and formed ZnO was reduced. Evaporated zinc was collected as crude ZnO and after the halogens removal process, ZnO was supplied to carbothermic reduction process under reduced pressure. Finally, high-purity metallic zinc was successfully recovered.
This paper is the recipient of the 2021 AIST Environmental Technology Best Paper Award. For more information about AIST awards, visit AIST.org/awards.
In 2019, a discrete-event computer simulation model was developed to assist NLMK in increasing slab productivity at its steel plant in Portage, Ind., USA. The model included all meltshop process activities from scrap charging at the electric arc furnace through casting and slab storage. The objective of the study was to identify the most cost-effective way to improve productivity by optimizing the implementation sequence of capital investments and operational changes. In the end, via detailed what-if analysis, the simulation study provided the client with a road map to achieve a 40% increase in slab production while minimizing the capital investment required.
The roll clusters of 20-high/Sendzimir mills are assemblies of solid rolls, backing bearings, arbors/shafts and support saddles, all seated to the housing’s precision bores. The static locations/contact mechanics of these components/bores form the roll cluster’s longitudinal and transverse geometries. For stability and proper function, these geometries must adhere to a series of necessary conditions and precise tolerances. This article examines how fine-scale imperfections in the roll cluster’s geometry influence precision light-gauge shape control performance, which may exceed the capabilities of conventional roll grinding practices, cluster setup strategies and the available dynamic shape actuation.