Utilization of blast furnace sludge for the removal of zinc from steelmaking dusts using microwave heating (original) (raw)
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Characterization of blast furnace sludge and removal of zinc by microwave assisted extraction
Hydrometallurgy, 2012
Significant quantities of sludge and slag are generated as waste materials or byproducts every day from steel industries. The blast furnace sludge (BFS) is considered to be highly problematic, due to zinc content. Therefore, new technological processes for recycling the sludge and dusts from metallurgical processes are still searched to find the most suitable method. One direction toward a cleaner environment is to use microwaves as energy source to enhance leaching processes of BFS. The presented work is focussed on the removal of zinc from BFS in an attempt to allow the reuse of the sludge with relatively high iron content in the subsequent production steps. Fine fractions of BFS are characterized and treated by the microwave assisted leaching for selective removal of zinc. The effects of extraction conditions such as microwave power, leaching agent, acid concentration, L/S ratio and extraction time for the zinc removal efficiency are evaluated. To completely describe the leaching kinetics, the shrinking core models are used to determine the apparent activation energy and the rate-limiting step of the reaction.
Journal of Sustainable Metallurgy, 2020
Recently, microwave energy has attracted increasing interest for accelerating thermal reactions. This study investigated the impact of microwave heating on the zinc recovery rate from electric arc furnace (EAF) and chromium converter (CRC) dusts. The results indicated that microwave heating required a lower temperature to recover zinc from EAF and CRC dusts compared with that in conventional thermal heating. For CRC dust, zinc recovery rates of 37.84% and 97.43% were obtained with conventional and microwave heating, respectively, at 850 °C. For EAF dust, zinc recovery rates of 79.88% and 98.20% were obtained with conventional and microwave heating, respectively, at 850 °C. The improved zinc recovery in this study was concluded to results from the rapidity of microwave heating and the interactions between the electromagnetic microwave field and the molecules of heated materials. Graphical Abstract
Zinc recovery from iron and steel making wastes by conventional and microwave assisted leaching
Acta Montanistica Slovaca, 2011
Significant quantities of sludge and dust are generated as a waste material or byproduct every day from iron and steel industries. Nowadays The occurrence and recovery of metallurgical wastes from steelmaking and iron making processes is a great problem, mainly due to the big amount and environmental pollution of these wastes by heavy metals. The future technology of fine-grain metallurgical wastes treatment is mainly the thing of ecological and financial limits. This work explains the removal of zinc from blast furnace sludge by hydrometallurgical process. The aim of this work was to carry out a chemical, physical, structural, and morphological characterization of these waste materials and subsequently to find out the best suitable method for the hydrometallurgical treatment. The experimental work includes full plant experiments. Extraction conditions such as the effect of microwave power, leaching agent, acid concentration, S/L ratio and extraction time on the zinc removal efficiency were evaluated. The main goal is to set the best conditions to transfer zinc into the solution while the iron should to remain in the solid phase.
Recycling of basic oxygen furnace steelmaking dust by in-process separation of zinc from the dust
Journal of Cleaner Production, 2016
High zinc content in solid wastes from basic oxygen furnace steelmaking offgas cleaning systems is one of the main barriers for source recycling of the solid wastes back into ironmaking and steelmaking process. Over-limit zinc loadings to blast furnaces might damage blast furnace refractory materials, and hence shorten blast furnace campaign life. In addition, high zinc input into blast furnaces might also cause operation difficulties of the blast furnaces, and thus decrease blast furnace productivities. Therefore, how to separate zinc from the solid wastes in an economic way becomes a crucial step for recycling of the solid wastes in sinteringeblast furnace ironmaking process. There are three general strategies of separating zinc from the solid wastes, which are referred to as before-process separation, post-process separation and in-process separation. In-process separation is to separate zinc from the solid wastes in the process while the solid wastes are being collected. In this research paper, industrial trials are reported on measuring zinc distributions in dry offgas cleaning systems of two ArcelorMittal basic oxygen furnace steelmaking plants. The results show that primary dusts contain negligible zinc and have good qualities comparable with virgin iron ores. Therefore, in-process separation strategy has a potential to be applied in existing basic oxygen furnace steelmaking offgas cleaning systems to make cleaner offgas byproducts without revamping the offgas cleaning systems. However, in order to recycle more of the solid wastes with low level of zinc, it will be needed to install high-efficiency primary dust collectors and more advanced offgas pre-conditioning mechanisms prior to the primary dust collectors.
Journal of Cleaner Production
Oily hot rolling mill (HRM) sludge containing a high percentage of iron oxides has been treated under microwave irradiation, and the products compared to hexane washed and thermal treated sludges. Metals present in the sludge act as a highly microwave-absorbent material, creating hot spots that trigger the stripping of the water and oils under air. The sludge looses 5 wt.% of water and volatiles under 5 min of microwave irradiation (1000 W at 2,450 MHz), which represents a similar reduction in weight as 4 h heating at 200 °C, but with savings in energy and time. Most importantly, after microwave irradiation, the material also shows an improvement in its rheological properties (free flowing and smaller particle size) and changes in its chemical composition. Microwaved samples are less oxidized than heated ones (lower Fe 3+ content), which is an advantage recycling the sludge as a source of iron with lower oxidation state necessitates a lower coke:ore ratio for blast furnace operation. Highlights • Oily hot rolling mill (HRM) sludge treated with microwave radiation. • Water and hydrocarbon content reduced by microwave treatment. • Reduction of the iron oxidation state of the iron oxides after microwave treatment.
On the Aqueous Recovery of Zinc from Dust and Slags of the Iron and Steel Production Technologies
International Journal of Metallurgical & Materials Engineering
Recently the iron and steel makers as well are much more concerned with the by-products and waste streams generated in their ferrous metallurgical industries. In general, the relevant minor or trace elements (Si, Mn, P, Al, S, As, Cu, Zn, K, Na, Ti, Cr, V, W etc.) are not concentrated very much in the different slags and dust produced and collected during the subsequent processing steps of iron and steelmaking. However, zinc can be an exception, especially when zinc containing (e.g. hot dip galvanized) steel scraps are recycled in electric arc furnaces (EAF) to produce new unalloyed steels. The paper describes, in short, a few examples of the recovery of some valuable metals from such byproducts, then reviews the major selective leaching processes tested or being applied to reclaim pure zinc compounds or metallic zinc as a by-product of the EAF secondary steel making technology. Based on own laboratory experiments the technical feasibility is also discussed of the selective leachability and removal rate of lead from the residues of the ammonia-ammonium carbonate (AAC) leaching of EAF dust. Secondary leaching of such residues obtained after AAC leaching was performed in laboratory autoclaves equipped with mechanical stirring and used up to 250°C.
THE APPLICATION OF CITRIC ACID SOLUTIONS FOR SELECTIVE REMOVAL OF ZINC FROM STEELMAKING DUST
Journal of Mining and Metallurgy, Section B: Metallurgy, 2021
Steelmaking dust is one of the wastes which are produced by ironworks. This kind of waste is a byproduct made mainly in electric arc furnace. Zinc content in dust is different and depends on the charge processed in the furnace. The basic technology used for recycling steelmaking dust is Waelz process however it requires a large amount of reducer and generates a lot of waste which need to be stored. First stage in this study was to analyze if steelmaking dust is safe to be exposed for atmospheric conditions. To verify this subject the dust exposed for two kinds of leaching, in standards of TCLP and EN-12457-2. The amount of extracted elements was too large that's why steelmaking dust must be treated as dangerous waste. Leaching in citric acid solutions was divided in four series. The first one was set to determine the time and temperature for most selective zinc leaching. Next series optimized three leaching parameters which were: citric acid concentration, liquid to solid phase ratio (l/s), and the stirring speed. Performed experiments showed the optimal conditions for selective leaching: temperature of 50 °C, leaching time of 60 minutes, citric acid concentration of 0.5 mol/dm 3 , l/s ratio of 10, and stirring speed of 250 rpm.
Zinc accumulation during recycling of iron oxide wastes in the blast furnace
Ironmaking & Steelmaking, 2006
Byproducts/wastes of iron-and steelmaking processes and steel scrap are the main sources of iron units recycled in the steel plants. Direct recycling of the iron oxide wastes (dusts and sludge) in the blast furnace (BF) is however hampered by its chemistry (.0. 1%Zn in the charge). Vaporisation, condensation, oxidation and circulation of zinc may collectively lead to the accumulation in the furnace. Very fine particles are deposited on other particles that have high surface areas which diminish BF refractory life and impair the quality of high quality pig iron produced. For effective continuous recycling of iron units, it is necessary to identify their sources, determine their composition and evolve device and appropriate technology for the treatment of zinc bearing units. The present paper analyses the process of zinc accumulation in the BF and derives an algebraic model to determine the extent of the accumulation. On the basis of analysis of zinc base formation, its recirculation in the furnace and other related productive units, a homograph (alignment chart) of zinc accumulation is designed. The paper also outlines the feasible processes of zinc removal from the close-looped system (sinter plant-BF-sinter plant).
Steelmaking Dust: Speciation of Zinc by Sequential Leaching
Inżynieria Mineralna
In electric arc furnace (EAF) steelmaking significant amounts of dust are generated. The main component in the dust is usually iron.Additionally, increased concentrations of metals which are volatile in the steelmaking process like zinc are found in the dusts. Duringcooling of the off-gas in the off-gas system the volatile metals are deposited on the dust particles. In electric arc furnace dust the zinccan be present in different compounds, for example as zinc oxide and zinc ferrite. Although recycling of EAF dust and utilization forzinc recovery are practiced in several countries approximately 50% of the EAF dust produced worldwide is still goes to landfill. In thisstudy the EAF dust from a mini mill was investigated by chemical fractionation. The experiment was carried out in a sequence of fiveleaching steps, where the residue from a leaching step was treated in the next step. The total zinc content of the EAF dust was approximately 6.4%. In the water-soluble fraction no zinc was ...
Research Journal of Applied Sciences, Engineering and Technology, 2016
Microwave Incinerated Sugarcane Bagasse Ash (MISCBA) was used in the exclusion of zinc from aqueous solution. Parameters of importance like initial metal concentration, adsorbent dosage and agitation time were examined to find their effect on the adsorption process. Respond surface methodology has been employed to enhance the process conditions based on Box-Behnken design. Response surface method suggest initial metal concentration of 50 mg/L, adsorbent dosage 1.0 g and contact time of 3 h with removal efficiency of 55.99% to be optimum conditions for zinc removal from aqueous solution. A high correlation coefficient of 0.9923 indicates the model is in agreement with the experimental values. The model indicates that adsorbent dosage is the major influencing factor among others responsible for the adsorption of zinc.