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Response curves of individual effects: (a) Oxidant, (b) type of aqueous solution and (c) temperature.
Source publication
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 an...
Contexts in source publication
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... observations are discussed below. Figure 8 shows the average response curves for the individual parameters to evaluate the effect of the ozone (considering that the ferric ion has the least effect in the Zn removal). The graphs were constructed with data from the tests that used the ozone and oxygen. ...
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... graphs were constructed with data from the tests that used the ozone and oxygen. The most significant comparative results were found for the oxidant (see Figure 8a), which Zn removal increased from 16% to 40% using oxygen and the ozone, respectively. However, alkalis removal was not affected by the change of oxidant. ...
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... the other hand, Fe loss increased from 4% to 9% when the ozone was employed. In the case of the type of aqueous solution, Figure 8b shows that the best result was obtained with H2SO4 where Zn removal increased from 20% and 18% to 80% using NH4Cl, HCl and H2SO4 respectively. Alkalis removal and Fe loss also increased when sulfuric acid was employed. ...
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... removal and Fe loss also increased when sulfuric acid was employed. In the case of temperature (see Figure 8c), Zn removal decreased by increasing temperature from 27 °C to 80 °C, while alkalis and Fe increased. Generally, in a leaching process, at higher temperature the velocity of dissolution is increased. ...
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... a zinc extraction, like those obtained in the studies cited in the table. Figure 8 shows the average response curves for the individual parameters to evaluate the effect of the ozone (considering that the ferric ion has the least effect in the Zn removal). The graphs were constructed with data from the tests that used the ozone and oxygen. ...
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... graphs were constructed with data from the tests that used the ozone and oxygen. The most significant comparative results were found for the oxidant (see Figure 8a), which Zn removal increased from 16% to 40% using oxygen and the ozone, respectively. However, alkalis removal was not affected by the change of oxidant. ...
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... the other hand, Fe loss increased from 4% to 9% when the ozone was employed. In the case of the type of aqueous solution, Figure 8b shows that the best result was obtained with H 2 SO 4 where Zn removal increased from 20% and 18% to 80% using NH 4 Cl, HCl and H 2 SO 4 respectively. Alkalis removal and Fe loss also increased when sulfuric acid was employed. ...
Context 8
... removal and Fe loss also increased when sulfuric acid was employed. In the case of temperature (see Figure 8c), Zn removal decreased by increasing temperature from 27 • C to 80 • C, while alkalis and Fe increased. Generally, in a leaching process, at higher temperature the velocity of dissolution is increased. ...
Citations
... Minerals 2022, 12,868 test, and 98.5% of the briquettes were more than 5 mm in size. The abrasion stren briquette fractions examined after 25, 50, 100, and 200 revolutions, defined as exceeding 5 mm in size, were 93%, 89%, 80%, and 64%, respectively. ...
Briquetting is a process in which fine materials unsuitable for use as such are agglomerated to achieve a larger particle size. Auger pressing is a novel briquetting method to efficiently improve the recycling of by-products from iron and steelmaking. The high-temperature properties of auger pressing briquettes mainly consisting of blast furnace sludge and mill scale were evaluated. The aim was to determine the suitability of the briquettes for blast furnace (BF) ironmaking by studying the reduction, swelling, and cracking behavior using a laboratory-scale furnace. The blast furnace simulator (BFS) capable of performing non-isothermal reduction experiments with changing gas compositions was used to simulate the different stages of reduction up to 1100 °C in an atmosphere with N2, CO, and CO2 gases. A commercial olivine pellet and a conventional industrial BF briquette were used as reference samples. The sample weight losses were monitored by thermogravimetry, swelling as a change in the volume, and cracking by visual inspection. The samples were analyzed using microscopes and an elemental analyzer. Based on the BFS experiments, the briquettes proved to be a promising raw material for BF use. They were of a self-reducing quality due to their carbon content and showed reduction to metallic iron faster compared to the reference samples. The swelling was slight, and despite the minor cracking the structure of the briquettes did not degrade.
... The traditional treatment methods for Zn-containing dust are hydrometallurgy and pyrometallurgy (Kul et al., 2015). In hydrometallurgy, acid (Jamali et al., 2020;Lutandula and Kashala, 2013;Steer and Griffiths, 2013;Wang et al., 2018) and alkaline leaching (Bakkar and Neubert, 2019;Chairaksa-Fujimoto et al., 2016;Zhang et al., 2017;Soria-Aguilar and Davila-Pulido et al., 2019) solutions are generally used. Wet processing is sensitive to raw materials, and it is difficult to optimize the process, making large-scale use impossible. ...
Theoretical calculations and experimental studies were used to investigate a process involving the evaporation, condensation, and separation of blast furnace dust with vacuum carbothermal reduction. The theoretical calculations revealed that the removal rate of metallic zinc from blast furnace dust by vacuum carbothermal reduction was > 99.6%, with a 800–900 °C reduction temperature range. The experimental results showed a 97.8% removal rate of metallic zinc in the reduced sample. The phase transformations of iron and zinc during the reduction process were ZnFe2O4 → Fe2O3 → Fe3O4 → FeO and ZnFe2O4 → ZnO → Zn(g), respectively. Metallic zinc in ZnFe2O4 phase was reduced, condensed, and collected after escaping in the gas form. These results demonstrated the feasibility of a novel process for recovering metallic zinc and high-grade iron-bearing raw materials from blast furnace dust.
... Soria-Aguilar et al. [5] contributed an article entitled "Oxidative Leaching of Zinc and Alkalis from Iron Blast Furnace Sludge". The sludge from a wet-off gas cleaning system of an iron blast furnace (BF) contains significant amounts of iron; however, this iron cannot be recycled due to its high content of zinc and alkalis. ...
A Special Issue of Metals was commissioned that was devoted to aspects of Mineral Processing and Hydrometallurgy [...]
... More resource-efficient management of sludges, especially recovery of the metals they contain, has also been considered. Metal extraction and recovery methods (Kaya et al., 2020) include oxidation de Jesus Soria-Aguilar et al., 2019), sulfidation (Liang et al., 2012;Kuchar et al., 2006), and other hydrometallurgical (Miškufova et al., 2006;Nair et al., 2008;Safarzadeh et al., 2008;Li et al., 2011;Moradkhani et al., 2012;Chi et al., 2013;Kamran Haghighi et al., 2014;Moghaddam, 2017a, 2017b;Siedlecka, 2020;Pourghahramani, 2015a, 2015b;Ö zbaş et al., 2013;Kelebek et al., 2004;Kumar Sahu et al., 2020) methods (also with ultrasonic (Li et al., 2010), microwave (Omran and Fabritius, 2018) and electrokinetic Tian, 2010a, 2010b;Liu and Wang, 2008) enhancements), and pyrometallurgical (Zhou et al., 2018;Li et al., 2020), and hybrid (Amaral et al., 2014;Rossini and Bernardes, 2006;Cantarino et al., 2012) treatments. Although the recovery approach decreases heavy metal pollution, the remaining sludge remains a disposal problem. ...
Zinc (Zn) in sludges from neutralisation of acidic emissions is a potential environmental pollutant and an element of interest for recovery. Findings regarding the elemental and mineralogical composition of such wastes were aggregated from the literature and examined together for a better understanding of management options, with a focus on Zn. Zn concentrations ranged from 0.006-22% in 46 acid mine drainage sludges, 0.009%-43% in 72 metal-finishing sludges, 0.024%-11.5% in 32 pyrometallurgical sludges, and 1.71-55.7% in 14 Zn production sludges. The main mineralogical characterization technique was X-ray diffraction, which found the dominant minerals to be calcite, gypsum, quartz, and iron oxides, but could not identify considerable proportions of amorphous phases. More than 60 mineral phases were observed. Crystalline Zn compounds identified included oxides, hydroxides, sulfates, sulfides, and metallic Zn; spinel, olivine and carbonate dominated in pyrometallurgical sludges. Zn may also be present in crystalline phases of low concentration, solid solution, and/or amorphous phases, which could be identified and characterised in more detail using other techniques. Overall, it is concluded that Zn occurs in high concentrations and includes phases that have high potential environmental mobility. Zn recovery seems feasible and would also enable harmless disposal of the residual.
... X-ray diffraction patterns of such dusts show that beside ZnO [9][10][11][12] and ZnFe2O4 [9,10] it also containes ZnS [11,12] and ZnCO3 [12]. In contrast to the Zn concentration in the dust from the first dedusting stage the Zn concentration in the residue from the second dedusting stage is usually considerably higher [1,13] Likewise, leaching of the sludge obtained in wet second-stage dedusting (BF sludge) was also investigated [14][15][16][17][18]. In the BF sludge Zn is found as ZnO [15] and as ZnFe2O4 [16,17]. ...
... In contrast to the Zn concentration in the dust from the first dedusting stage the Zn concentration in the residue from the second dedusting stage is usually considerably higher [1,13] Likewise, leaching of the sludge obtained in wet second-stage dedusting (BF sludge) was also investigated [14][15][16][17][18]. In the BF sludge Zn is found as ZnO [15] and as ZnFe2O4 [16,17]. ...
... The amount in the residual fraction was 3%, indicating that the amount of ZnFe2O4 in the dust was small. The distribution of Zn in the BF filter dust is therefore more similar to that in the BF dust [9][10][11][12] than to the distribution in BF sludge [15][16][17]. ...
... Nevertheless, although the process works, the liquid-to-solid ratio is high (L/S = 10). By leaching BF sludge with 0.1-M H 2 SO 4 in a strongly oxidizing ozone gas, the co-dissolution of iron could be suppressed, while 85% of the zinc could be leached [63]. ...
The state of the art for the recovery of metals from steel industry by-products using hydrometallurgical processes is reviewed. The steel by-products are different slags, dusts, and sludges from a blast furnace (BF), basic oxygen furnace (BOF), electric arc furnace (EAF), and sinter plant, as well as oily mill scale and pickling sludge. The review highlights that dusts and sludges are harder to valorize than slags, while the internal recycling of dusts and sludges in steelmaking is inhibited by their high zinc content. Although the objectives of treating BF sludges, BOF sludges, and EAF dust are similar, i.e., the removal of zinc and the generation of an Fe-rich residue to be returned to the steel plant, these three classes of by-products have specific mineralogical compositions and zinc contents. Because wide variations in the mineralogical composition and zinc content occur, it is impossible to develop a one-size-fits-all flow sheet with a fixed set of process conditions. The reason for the interest in EAF dust is its high zinc content, by far the highest of all steel by-products. However, EAF dust is usually studied from the perspective of the zinc industry. There are not only different concentrations of zinc, but also variations in the all-important ZnO/ZnFe 2 O 4 (zincite-to-franklinite) ratio. In many chemical processes, only the ZnO dissolves, while the ZnFe 2 O 4 is too refractory and reports to the residue. It only dissolves in concentrated acids, or if the dust is pre-treated, e.g., with a reductive roasting step. The dissolution of ZnFe 2 O 4 in acidic solutions also brings significant amounts of iron in solution. Finally, due to its high potassium chloride content, sinter-plant dust could be a source of potassium for the fertilizer industry.
Graphical Abstract
Steel metallurgical dust and sludge is an important secondary resource, containing up to 20 valuable elements and compounds. It is the goal of various dust treatment processes to efficiently recover the valuable components in the dust and sludge while minimizing the environmental hazards of the dust and sludge. This paper summarizes the chemical composition, phase composition and particle size distribution characteristics of typical steel metallurgical dust and sludge. The chemical composition of secondary ash and the physical characteristics of rotary kiln tailings are analyzed, and the results show that the rare elements in the dust and rotary kiln tailings have high value recovery conditions. The reaction mechanism, process flow, domestic and foreign applications, advantages and disadvantages of conventional treatment methods such as pyrometallurgical process, wet process and physical process were discussed in depth. Conventional treatment processes often only target the separation and recovery of some elements with high content, and do not achieve the total resource utilization of dust and sludge. With the increasing shortage of resources and stricter environmental protection requirements, a single treatment process can no longer meet the requirements, and the technical solution of pyroenrichment–wet-separation–multi-process coupling extraction and complete recycling is proposed. Through the analysis of the reaction mechanism, the evolution and migration mechanism of valuable elements such as Zn and Sn in the pyroenrichment, wet separation and slag utilization systems are elucidated. It is proposed that the collaborative extraction technology of Rb, Cs, and other scattered elements should be developed in the future for the total utilization process to develop toward a more refined method. It is hoped that the above work can provide a reference for the harmless treatment and total resource utilization of difficult-to-treat dust and sludge in the steel industry.
The reduction in the fresh water supply and increase in the domestic effluents with increase in population and urbanization in the Pakistan force the farmers to use untreated sewage water for the irrigation purposes. Besides high nutrient content Sewage water also have source of metal contamination in the food chain. The present field study was conducted to compare the nickel (Ni), copper (Cu) and lead (Pb) contamination in vegetables grown on soils irrigated with sewage water and canal water in Sargodha, Punjab, Pakistan. The Ni, Cu and Pb contamination was assessed using soil quality indices i.e., contamination factor (CF), metal translocation factor (MTF), pollution load index (PLI), geo-accumulation index (Igeo) and ecological risk index (ERI) were calculated in the collected samples. The physico-chemical properties of soil and water samples were determined. Based on the results, it was revealed that sewage irrigated areas were at higher risks of metals contamination compared to canal irrigated areas. From the studied metals, Pb showed highest contamination potential based on the soil quality indices. In sewage irrigated sites, metal concentrations were found higher in edible parts of the vegetables confirming that sewage water contains and supply more metals than canal irrigated water and pose more health and ecological risks.
Given the shortage of zinc resource, the low utilisation efficiency of secondary zinc resource, and the crucial problem that the synchronous dissolution of zinc from different mineral phases, an activation pretreatment method merged with calcium activation and microwave heating approach was proposed to enhance the zinc leaching from complex encapsulated zinc-containing metallur-gical residues (ZMR). Results indicated that under the optimal pretreatment conditions, including microwave activation temperature of 400 • C, CaO addition of 25% and activation time of 20 min, the zinc leaching rate reached 91.67%, which was 3.9% higher than that by conventional roasting pretreatment. Meanwhile, microwave heating presents excellent treatment effects, manifested by the zinc leaching rates, all exceeding that of conventional roasting under the same conditions, while the process temperature is decreased by 200 • C. In addition, XRD and SEM-EDS analysis denoted that microwave calcification pretreatment can effectively promote the transformation of the refractory zinc minerals like Zn 2 SiO 4 and ZnFe 2 O 4 into the easily leachable zinc oxides. The distinctive selective heating characteristics of microwave heating strengthened the dissociation of mineral inclusion, and the generated cracks increased the interfacial reaction area and further enhancing the leaching reaction of zinc from ZMR.
