Recovery of Chromium from Stainless Steel dust (original) (raw)
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Extraction of Chromium as Sodium Chromate from Stainless Steel Dust
The Journal of Solid Waste Technology and Management, 2011
The objective of this investigation was to recover chromium as sodium chromate of 99.5% purity from stainless steel dust. The dust contains 7.72% chromium obtained from stainless steel processing plants. The stainless steel dust mostly contained iron in oxide form along with chromium, nickel (1.71%) and manganese (3.55%). The steel dust was roasted with soda ash followed by water leaching to recover the major constituent chromium. It was found that roasting at 1073 K for 90 minutes resulted in maximum (95%) chromium recovery. Kinetics of sodium chromate formation followed a topochemical model involving chemical reactions at the surface with activation energy of 39 kJmol-1. TG/DTA, XRD phase identification and SEM microphotographs confirmed the experimental observation and the mode of reaction.
The Journal of Solid Waste Technology and Management
Journal of Solid Waste Technology and Management
This investigation deals with the recovery of chromium as sodium chromate of 99.5% purity from stainless steel dust containing 7.72% chromium obtained from stainless steel processing plants. The stainless steel dust mostly contained iron in oxide form along with chromium, nickel (1.7 1%) and manganese (3.5 5%). The steel dust was roasted with soda ash followed by water leaching to recover the major constituent chromium. It was found that the roasting at 1073 K in 90 minutes resulted in maximum (95%) chromium recovery. Kinetics of sodium chromate formation followed topochemical model involving chemical reactions at the surface with activation energy of 22 kJmol" 1. TG/DTA, XRD phase identification and SEM-EDX confirmed the experimental observation and the mode of reaction.
Adsorption of Chromium from Steel Plating Wastewater Using Blast Furnace Dust
Revista Internacional de Contaminación Ambiental
In this work, blast furnace dust (BFD) obtained from a steel dust collector is used as low-cost adsorbent material for chromium removal from steel industrial plating wastewater. This study shows that BFD present physical and chemical characteristics, such as chemical composition, magnetic properties and particle size, suitable for application in adsorption of ions such as chromium. Different kinetics approaches and isotherms models were evaluated to describe the adsorption process. According to results, chromium adsorption follows intra-particle diffusion with adsorption in active sites. Freundlich and Dubinin-Radushkevich isotherms parameter and low free energy obtained from isotherms studies indicate that chromium adsorption occurs by of a cooperative physical adsorption process, due to the electrostatic attraction between protonated FeOH + and HCrO 4-. Although the results indicate that BFD adsorb partially the chromium, it could represent an attractive low-cost absorbent option as complementary method for removal of chromium in the steel plating wastewater treatment.
Effect of Alkali and Acid Concentration in Extraction of Chromium III from Tannery Solid Waste
2016
Samples of solid waste from the tanning industry in the form of buffing and shaving wastes were subjected to series of treatment in an attempt to extract chromium III from them. Results obtained from analysis of samples containing this metal show that leather buffing waste contained more moisture and volatile matter than that in leather shaving waste, while the latter contained more ash and chromium than the former. An upward trend in extractable chromium concentration in both leather shaving waste and leather buffing waste was observed with increase in the amount of alkali (sodium carbonate) Spectroscopic analysis of both samples after pretreatment with different concentrations sodium carbonate also indicate that the concentration of chromium in leather shaving was higher than that in its counterpart. The percentage recovery of chromium from both samples was determined with considerations given to parameters to examine the effect of acid concentration, and contact time. In most cas...
Chromium recovery from tannery sludge and its ash, based on hydrometallurgical approach
2018
Chromium-rich tannery sludge derives from the physicochemical treatment of tannery wastewaters and can be considered as a valuable by-product. The recovery of chromium from tannery sludge and from the respective ash constitutes an alternative process of tannery sludge treatment, in order to dispose of safely. Chromium recovery was investigated, based on simple hydrometallurgical processes (i.e. leaching by using concentrated acids), either directly applied in the air-dried sludge, or from the respective ash, resulting from thermal treatment under anoxic conditions. The major parameters, influencing the effectiveness of leaching process were investigated, i.e. the continuous stirring with various leaching time, pH and temperature values, as well as different liquid/solid ratios (L/S) and different acids/solvents (H2SO4 or HCl) to optimize the recovery process. The results from the chromium leaching tests revealed the satisfactory leaching of trivalent chromium directly from the initi...
Extraction Of Chromium From Leather Chrome Shaving Dust
Leather processing involves transformation of putrescible animal hides and skin into non putrescible leather. Leather industry generates a huge amount of solid waste containing chromium. These solid wastes were disposed of through land filling which causes leaching out of in soil and water. Now a day increasing environmental legislations have encouraged tannery industry to develop a new technology. In this study, we incinerated chrome shaving dust at 500oC to 7000C for chromium extraction. Various oxidizing acids with different concentration were used for chromium extraction. Extracted chromium was measured by Atomic Absorption Spectrometry. Recovery of chromium was in the range of 297 mg/L to 222 mg/L. Nitric acid extracted maximum amount of chromium while sulfuric acid extracted minimum amount of chromium.
Journal of Cleaner Production, 2016
This study focuses on the recycling of stainless steel (SS) slags containing about 1.2 wt% of chromium (Cr). The selective recovery of Cr from SS slag by a hydrometallurgical method (alkaline pressure leaching) was investigated. Leaching experiments were carried out based on 2 4-1 factorial design of experiment (DOE) with the following parameters: NaOH concentration, temperature, leaching time, and mechanical activation (MA). Results show that temperature and MA are the most influencing factors for an enhanced Cr leaching. The maximum Cr leaching was 46% at 1 M NaOH, 240 o C, 6 h, MA 30 min, while the matrix material was dissolved only to a limited extent (Al 2.88%, Si 0.12%, Ca 0.05%). After Cr leaching followed by alkali washing, a carbonation treatment is proposed to stabilise the remaining Cr in the matrix material and make the subsequent recycling of the matrix material as a construction material possible. 10 Chromium can be recovered from the leachate and alkali/water washing solution by ion exchange or precipitation.
Thermal treatment of stainless steel dusts for leaching
Acta Metallurgica Slovaca, 2013
Many pyrometallurgical, hydrometallurgical and combined processes have been developed to allow better utilization of steelmaking dusts. The dusts contain metals and compounds that can harm the processes and one of these elements is zinc that is present in the flue dusts as zincite ZnO and franklinite ZnFe 2 O 4. The effect of alkaline roasting on the dissolution of stainless steel flue dusts in acid and alkaline leaching was studied. The extraction of zinc from EAF dust was not significantly improved in alkaline leach (40-50 %) but there was indication of better extraction in acid leach (over 90 %). No improvement in extraction from AOD dust was seen either in alkaline (max. 58 %) or acid leach (max. 72 %). The acid leach of synthetic ferrite resulted in less than 32 % Zn recovery, and this must be studied further to find out the effect of franklinite in the dusts.
Obtaining sodium chromate from ash produced by thermal treatment of leather wastes
Chemical Engineering Journal, 2010
Currently, 80-90% of leather production uses chromium tanning; thus, the trimmings and shavings resulting from the manufacturing of leather goods create a waste with a high pollution potential. One alternative for handling this scrap-leather waste is thermal treatment (gasification and combustion). The ashes generated during this process are rich in chromium, containing between 50% and 60% chromium oxide (Cr 2 O 3) by mass, and the ashes can thus potentially be utilized as a source of chromium for the synthesis of sodium chromate (Na 2 CrO 4). With the aim of improving on the results of previous attempts made to recover chromium from these ashes, in this work, the use of sodium nitrate to oxidize the trivalent chromium to the hexavalent form was studied. The resulting conversion of chromium (III) to chromium (VI) achieved was over 94%, and the sodium chromate obtained from the ashes showed physical properties similar to the commercial product.
Journal of Iron and Steel Research International, 2018
Stainless steel crude alloy recovery from direct smelting of low-grade chromite, nickel laterite and manganese ores was investigated. The mixed low-grade ores were directly smelted in an elevator furnace at smelting temperatures ranging from 1550 to 1600°C. Smelting experiments were conducted in a laboratory elevator furnace equipped with 8 U-shaped highquality molybdenum disilicide heating elements. A low-grade coal was used as the reductant. Experimental results showed that the recovery of Fe, Cr, Ni, Mn and Si within the alloy increased from 34.22, 60.27, 57.14, 25.42 and 13.02% to 69.91, 99.26, 86.02, 60.8 and 34.21%, respectively, when the temperature was increased from 1550 to 1600°C. There was a general increase in the total recoveries of Fe, Cr, and Ni in the alloy with CaO addition increasing from 0.4 g up to 1.2 g. However, the recoveries of Mn and Si vividly decreased as the CaO contents were increased. In general, the recoveries of the metal contents of the crude alloy increase with the increase in the amount of manganese ore. Compared to the recoveries of Fe, Cr, and Ni when CaO was added, the recoveries of Fe, Cr and Ni were lower when manganese ore was used as an additive.