Within the steelmaking industry, a large amount of zinc-bearing waste is produced which cannot be effectively treated through integrated steel mills. Concurrently, zinc smelters generate waste residues containing significant amounts of iron and zinc which are stored or landfilled. The zinc concentration of iron and steelmaking residues inhibits its recycling to the blast furnace but is insufficient to be sent directly to the zinc producers. Consequently, a means of up-concentration is required. The pilot HIsarna ironmaking furnace has shown potential for processing secondary iron-bearing resources. Furthermore, zinc can be concentrated in the off-gas flue dust, providing an enriched input for zinc smelters. The potential recyclability of blast furnace (BF) and basic oxygen furnace (BOF) dust and ‘goethite’ residue from the zinc industry has been studied. The input materials have been comprehensively characterized and their reduction–vaporization behavior, has been investigated. Individual samples were tested at temperatures of up to 1300 °C. Here, it was shown that minimal reduction of iron and volatilization of zinc occurred in the goethite and BOF samples. Conversely, even at 1000 °C, the BF dust showed complete reduction of iron and removal of zinc within 30 min. This was due to its high carbon content (40 wt%) which can act as a reductant. Consequently, mixtures of BOF dust and goethite with BF dust were studied. It has been shown that mixtures of 30:70 BF dust to goethite and 20:80 BF dust to BOF dust are suitable for recovering zinc to the gas phase and fully reducing the contained iron. Graphical Abstract: [Figure not available: see fulltext.]

HIsarna is a novel ironmaking process with great raw materials versatility that is attractive for various secondary resources. Among the materials that can be recycled, there is steel scrap which is fed to the furnace bath through an inclined chute. The velocity distribution of the scrap particles along the chute affects the particles’ distribution on the liquid slag and, thereupon, the efficient operation of the reactor. In this study, the flow of steel scrap particles along an inclined chute with the same dimensions as those of the actual chute of the HIsarna plant is investigated experimentally and numerically. The simulations are validated using chute tip velocity and mass fractions collected at the different compartments of a sampling device. Translational and angular velocity distributions along and across the chute are reported, and the effect of different parameters are investigated. The impact of the shape of the particles on the simulation process is found to be negligible. The angular velocity distribution in cross-sections of the chute exhibited a V-shaped orientation, whereas the translational velocity displayed similar values across the cross-sections. Moreover, translational velocity appeared to increase with increasing inclination angles, whereas angular velocity increased with decreasing batch size.

Pyroprocessing of spent nuclear fuels is an electrochemical separation method where spent metallic fuel is dissolved in a molten salt bath to allow uranium (U) and plutonium (Pu) to be isolated from fission products (FPs) and other impurities. This allows the useful materials to be reused in mixed oxide fuel (MOx) or further refined to new reactor fuel. Monitoring the changing concentrations of U, Pu, FPs and other species inside a molten salt vessel presents a unique challenge which laser-induced breakdown spectroscopy (LIBS) may be able to overcome, due to its ability to simultaneously analyse multiple elements using a single measurement with stand-off capability in situ. In this study, samples of praseodymium (Pr), holmium (Ho) and erbium (Er) chloride (LnCl3) in LiCl + KCl eutectic (LKE) salt were analysed with LIBS. Multiple laser pulse energies were tested to maximise the signal to background ratio, the best results were obtained at the lowest pulse energy of 85 mJ per pulse. Forward interval Partial Least Squares (iPLS) regression was used to create predicted versus measured concentration models for each element. This method achieved Root Mean Squared Error of Cross Validation (RMSECV) values of between 3.20 × 10-3 and 16.3 × 10-3 mmolLn gLKE-1 for single lanthanide samples and 2.84 × 10-3 and 7.62 × 10-3 mmolLn gLKE-1 for mixed samples of all three lanthanide elements. Limits of quantification of between 1000 and 9000 ppm suggest LIBS should be a candidate for on-line analysis of elemental concentrations during pyroprocessing.

The steelmaking industry produces large quantities of zinc-bearing wastes of varying forms that cannot be treated through integrated steelmaking processes. Simultaneously, by-products of the zinc industry containing great amounts of iron and zinc are stored or landfilled. The amount of zinc in these materials is generally below that which is of value to be recycled directly to the zinc smelter, consequently a method of concentration is required. Tata Steel owns and operates the pilot HIsarna ironmaking plant which, due to its high raw materials flexibility, is attractive for the purpose of processing secondary iron sources. Furthermore, it can facilitate the simultaneous recovery of a zinc-enriched flue dust. The high temperature behaviour of various waste materials will be presented with regards to their recyclability in the HIsarna furnace. Blast furnace (BF) sludge and basic oxygen furnace (BOF) sludge from Tata Steel IJmuiden have been studied along with ‘goethite’ waste produced by Nyrstar. The various input materials have been comprehensively characterised and their reduction/vaporisation behaviour recorded. Mixed samples have been produced and tested in order to define the most appropriate form of delivery of these materials to the HIsarna furnace.

The feasibility of employing ion-exchange resins for the selective removal of uranium from a complex waste effluent has been investigated. The source of the effluent is a treatment process to reduce the volume of a spent uranium containing catalyst prior to its immobilisation and disposal in South Korea. Commercial anion exchange and chelation resins have been screened, along with an in-house synthesized polyamine functionalized resin. The Langmuir isotherm model produced the best fit for UO₂ ²⁺ binding to all resins, with Purolite MTS957, a mixed sulfonic/phosphonic acid functionalised resin, showing the highest equilibrium adsorption capacity for UO₂ ²⁺, 96.15 mg g⁻¹. The Modified Dose-Response Model was found to adequately represent breakthrough across all flow rates used and for all resins tested under dynamic testing conditions. The maximum uranium loading capacities under dynamic conditions for simulant and real wastes were established as 131.52 mg g⁻¹ and 68.62 mg g⁻¹, respectively. Purolite MTS957 effectively decontaminated the real effluent to uranium levels below the Korean release limit of 1 mg L⁻¹. Over 99.9% uranium was successfully eluted from the resin bed in under 20 BV with a mixed sodium carbonate/sulfate eluent.