Barsha Dash - Independent Researcher (original) (raw)

Papers by Barsha Dash

International journal of metallurgical engineering, 2012

Hydrated alu mina fro m three different sources like sodium alu minate liquor, waste alu miniu m ... more Hydrated alu mina fro m three different sources like sodium alu minate liquor, waste alu miniu m dross and synthetic salt like alu miniu m sulfate were studied to obtain various form of alu miniu m hydro xide. Boeh mite (A l 2 O 3 .H 2 O), a form of hydrated alu mina, has better performance in obtaining alu mina, as the enthalpy of dehydration of boehmite is less as compared to gibbsite due to the less number of water mo lecules in the crystal lattice as compared to gibbsite. Precipitation of hydrated alumina was also studied by using synthetic alu miniu m sulfate solution with aqueous ammonia and alternating the sequence of reagent addition. Subsequently, the variation in the p H of precip itation and fo llo wed by variat ion of the ageing temperature produced a range of hydrated alu mina with different phases and crystallin ities. In another option hydrated alu mina was precipitated fro m the sulfuric acid leach liquor of waste aluminiu m dross by varying the pH of the precipitation followed by temperature o f ageing.

Reclamation of tungsten from spent HDS catalyst: a detailed study

Indian Chemical Engineer

The awareness of the depletion of high grade ore is of paramount importance now-a-days for all th... more The awareness of the depletion of high grade ore is of paramount importance now-a-days for all the metallurgical industries and researchers. For the conservation of resources, processing of low and lean grade ores is very much essential. Moreover, the recycling and reuse of the secondaries must be the core strength in that context. The spent catalyst obtained from a petroleum refinery was having 20.33% WO3 and 49.14% Al2O3 as major part of the matrix. The spent catalyst was devolatilized at 650°C to remove the oils, organics and other volatile matter. The devolatilized spent catalyst was processed treated with 8% NaOH at 90°C for 3 h to dissolve tungsten as sodium tungstate. The W bearing liquor was treated with H2SO4 to precipitate tungstic acid at pH 1.0. and subsequent production of tungsten trioxide by roasting at 700°C and tungsten metal with 99.91% purity by reduction roasting by H2 gas has also been reported. The alkali leached residue was leached with 10% sulphuric acid at 80°C for 2 h so as to extract nickel and later on precipitated as nickel hydroxide.

Materials Advances, 2022

This article summaries an approach for removal of organic dyes like Congo red through mesoporous ... more This article summaries an approach for removal of organic dyes like Congo red through mesoporous alumina. Industrial effluents that contain dyes need treatment before discharging into surface water. Adsorption method...

Materials Today: Proceedings, 2020

Aluminosilicates are interweaved network of aluminates and silicates having intermolecular and in... more Aluminosilicates are interweaved network of aluminates and silicates having intermolecular and intramolecular porosity for which they find application in the area of adsorption, catalysis, pyrolysis and so on. They maintain the thrust of their existing applications and still entail new applications within the fields of chemical process and separation. The product phase and properties of the aluminosilicate vary with varying synthetic methods such as the sequence of addition of reagents which is outlined here in this study. The sequence of addition of aluminium iso propoxide and sodium silicate is divided into three parts. The phases obtained are zeolite, and crystoballite alpha in part-1. The phases of part-2 are sodalite and crystoballite beta. In part-3 the phases are mostly zeolite.

ACS Omega, 2020

To recover potassium from feldspar, a biowaste, i.e., eggshell, was used. The chief composition o... more To recover potassium from feldspar, a biowaste, i.e., eggshell, was used. The chief composition of eggshells is calcite. As it is a rich source of Ca, hence it is used with HCl to produce calcium chloride. Feldspar is an aluminosilicate mineral that bears potassium in the interstitial sites. To unlock the potassium from the interstitial sites, it was roasted with calcium chloride prepared by mixing eggshell and hydrochloric acid. At the roasting temperature, CaCl 2 melts and penetrates into the aluminosilicate matrix to replace K with Ca. Potassium ion released from the silicate matrix combines with chloride ions to form potassium chloride, which solubilized in water during the leaching process of the roasted feldspar. For elucidation of the mechanism of the roasting process, the shrinking core model was applied to the roast−leach data, and diffusion through the product layer was inferred as the rate-determining step. The order of the roasting process was found to be 2.158 and activation energy calculated to be 155.3 kJ/mol. Apart from potassium, sodium and excess calcium also got co-leached. To recover potassium from the leach liquor selectively, sodium perchlorate was added to precipitate potassium as KClO 4. Further, potassium perchlorate was thermally decomposed to give fertilizer grade potassium chloride (purity: 99.81%).

Advancements in Civil Engineering & Technology, 2018

Crystalline β-cobalt hydroxide (β-Co(OH)2) of different morphologies have been successf... more Crystalline β-cobalt hydroxide (β-Co(OH)2) of different morphologies have been successfully synthesized with the addition of sodium hydroxide to cobalt nitrate solution and aging in the mother liquor. The rate of NaOH addition, ranging from 0.1 mL/min to 10 mL/min, influences the surface morphology with the obtained storage capability of the respective electrode. Characterization of the β-Co(OH)2 was fully developed, including X-ray diffraction, scanning and transmission electron microscopy, and BET analyses. At a lower rate of NaOH addition, particles are like platelets, while for a higher rate (≥2 mL/min) grains are fused together forming a larger crystallite size. This result is supported by the X-ray diffraction structural analysis, where the phase evolution of (002) plane becomes distinct for the higher rate of NaOH addition. Lithium cobalt oxide (LiCoO2) was synthesized through oxidation from the as-prepared β-Co(OH)2 and LiOH. The electrochemical perfor...

Nanomaterials (Basel, Switzerland), Jan 31, 2017

A facile hydrothermal route to control the crystal growth on the synthesis of Co₃O₄ nanostructure... more A facile hydrothermal route to control the crystal growth on the synthesis of Co₃O₄ nanostructures with cube-like morphologies has been reported and tested its suitability for supercapacitor applications. The chemical composition and morphologies of the as-prepared Co₃O₄ nanoparticles were extensively characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Varying the temperature caused considerable changes in the morphology, the electrochemical performance increased with rising temperature, and the redox reactions become more reversible. The results showed that the Co₃O₄ synthesized at a higher temperature (180 °C) demonstrated a high specific capacitance of 833 F/g. This is attributed to the optimal temperature and the controlled growth of nanocubes.

Pathway of Sucrose Oxidation in Manganese (Pyrolusite) Nodule

Industrial & Engineering Chemistry Research, 2015

Polymetallic sea nodules are the potential resources of copper, cobalt, manganese, and nickel. Th... more Polymetallic sea nodules are the potential resources of copper, cobalt, manganese, and nickel. The exploration and exploitation of manganese nodules are necessary to meet the future demands of Mn in the world. This work describes the valuable extraction of Mn through an innovative approach of using sucrose as a reductant. The metal extraction from the nodule leaching was studied in ambient temperature (27 °C) and at an elevated temperature 90 °C with and without agitation. In both cases, 99.9% of Mn was extracted while the extraction time appears to be significantly low (2 h) at 90 °C but it requires a longer time of 24 h at 27 °C. The optimum sucrose concentration selected was 7% (w/w) of nodule for maximum metal extraction. With use of 10% (v/v) H2SO4, 7% (w/w) sucrose at 90 °C, and solid to liquid (S/L) ratio of 1:10 the achieved metal recovery figures were the following: Mn >99%, Ni 98%, Cu 87%, Co 83% in 2 h. The oxidation pathway of sucrose is outlined in this study with the aid of mass spectrometry...

Transactions of Nonferrous Metals Society of China, 2015

Aluminium hydroxide precipitation from synthetic sodium aluminate solution was studied in the pre... more Aluminium hydroxide precipitation from synthetic sodium aluminate solution was studied in the presence of hydrazine or hydrogen peroxide. The addition of low concentration of hydrazine is found to be effective, while higher amount of hydrogen peroxide is required to generate similar effect. XRD data confirm the product phase to be gibbsitic by nature. The scanning electron micrographs (SEM) show that agglomerated products form in the presence of hydrazine while fine discrete particles are produced with hydrogen peroxide. The probable mechanism of precipitation in the presence of hydrazine and hydrogen peroxide is also discussed.

Studies on characterization and leaching of malachite ore

The present study reports development of a process to extract copper from malachite ore available... more The present study reports development of a process to extract copper from malachite ore available at Congo region. The ore was subjected to X-Ray Diffractograms (XRD) and Scanning Electron Microscope (SEM) tests along with the chemical analysis. The major phases found were malachite and chalcocite. The major gangue was quartz. The total copper content was estimated to be 19% and a relative (not fully quantitative) estimation of malachite and chalcocite were found to be 16.31% and 2.68% respectively. Leaching of malachite using 0.6 molar sulphuric acid was completed for both 10% and 20% of pulp density and 5 min was sufficient to extract all the copper values into the solution. Most of the chalcocite and gangue stayed back in the residue. The recovery of copper was close to 75%.

Production of g-alumina from waste aluminium dross

Processing of aluminium dross is one of the most challenging tasks because of its toxic nature. T... more Processing of aluminium dross is one of the most challenging tasks because of its toxic nature. The dross generated while melting at various facilities is generally remelted with salts to recover residual metal values. The remaining residue dross contains mostly aluminium oxide, alloying elements and salts such as NaCl or KCl. This residue dross while stock piling creates pollution of the adjoining area as salts leach out to water stream and also emits harmful gases. In the present study domestic aluminium dross was treated for developing a suitable process flow sheet to obtain g-alumina a high valued product. Initially H 2 SO 4 leaching was carried out for both un-washed and washed dross. With un-washed dross the leaching efficiency achieved was 7171% but washing of dross followed by leaching raised the recovery to 7184%. Washing of dross is essential to have higher alumina recovery and also to recover salt for recycling. The liquor obtained after treatment of the dross with acid was...

Medium grade siliceous manganese ore containing 38.22% Mn was leached in sulphuric acid medium us... more Medium grade siliceous manganese ore containing 38.22% Mn was leached in sulphuric acid medium using shredded newspaper as reducing agent. Objective of the present study was to investigate the effectiveness of ligno-cellulosic base wastes such as used newspaper as a reducing agent. The experimental parameters chosen for this study were: H 2 SO 4 concentration (2-5% v/v), temperature (60-90 0 C), reductant to ore ratio (0.4-1) and ore particle size (57 – 274 µm). Optimum conditions for >90% extraction were: 90 0 C, 5% H 2 SO 4 (v/v), reductant to ore ratio 0.5, 8 h, 10% pulp density and ore particle size -100 µm. Newspaper was found to be equally effective as a reducing agent for low grade ore (15.83% Mn) also wherein the amount of reductant and acid needed were proportional to Mn content of the ore. The leach solution was enriched to 87 g/L by recycling process. The enriched solution was purified by pH adjustment to 4.7 using 20% lime slurry. MnSO 4 .H 2 O was crystallized from p...

Minerals Engineering, 2014

The separation of nickel has been carried out from a waste solution containing 3.18 g/L Ni with o... more The separation of nickel has been carried out from a waste solution containing 3.18 g/L Ni with other impurities such as Fe, Zn, Cu and As. Iron was removed by precipitation and Cu and Zn were removed by solvent extraction using LIX 622N and NaTOPS-99, respectively. After removal of all these impurities nickel was extracted by 1.5 M NaTOPS-99 in two counter-current stages at A:O ratio of 3:1 and the loaded organic was stripped with 30 g/L H 2 SO 4 at phase ratio of unity. The strip solution of nickel was treated with Al 2 (NO) 3 Á 9H 2 O for co-precipitation by increasing the pH of solution with 1 M NaOH up to 10. The Ni-Al layered double hydroxide was confirmed through XRD characterization.

Recovery of Co metal and Electrolytic Manganese Dioxide (EMD) from Co–Mn sludge

Hydrometallurgy, 2015

ABSTRACT Keywords: Co–Mn separation Sulphide precipitation Electrolytic Manganese Dioxide (EMD) C... more ABSTRACT Keywords: Co–Mn separation Sulphide precipitation Electrolytic Manganese Dioxide (EMD) Co metal Spent CMB catalyst A process flow sheet has been developed to produce cobalt metal and Electrolytic Manganese Dioxide (EMD) from Cobalt–Manganese Bromide (CMB) spent catalyst sludge. The Co–Mn sludge was leached in sulphuric acid media followed by the removal of organic matter from the leach liquor through adsorption by activated char-coal. Co–Mn separation was carried out by precipitating cobalt as mixed cobalt sulphide. The cobalt mixed sul-phide was roasted and then leached in sulphuric acid to produce cobalt sulphate solution. Co metal and EMD were electrodeposited from their respective sulphate solutions. The optimal conditions during sludge leaching, Co–Mn separation, roasting of Co mixed sulphide, dissolution of the roasted material, electrodeposition of Co metal and EMD have been studied. The EMD was characterized for its suitability for the use in batteries and a ten-tative flow sheet for processing Co–Mn sludge is presented.

International Journal of Advanced Materials Manufacturing and Characterization, 2013

Influence of alternative alkali reagents on Fe removal during recovery of Mn as Electrolytic Manganese Dioxide (EMD) from Mn sludge

Hydrometallurgy, 2013

ABSTRACT Flow sheet for recovery of Mn values from Mn sludge, a by-product obtained during proces... more ABSTRACT Flow sheet for recovery of Mn values from Mn sludge, a by-product obtained during processing of the Mn nodules through ammonia–ammonium sulphate–sulphur dioxide leaching process route as Electrolytic Manganese Dioxide (EMD) was developed. The unit operations include dissolution of Mn sludge with sulphuric acid in presence of activated charcoal, purification of liquor in two stages—removal of Fe by adjusting pH to ~ 4 followed by precipitation of other impurities as sulphides by addition of Na2S. The purified liquor was electrowinned for producing EMD. During first stage purification, Fe precipitation was carried out with CaO that resulted in loss of Mn due to its entrapment in the gypsum. The paper discusses use of alternative alkali reagents MgO and NaOH to minimise the Mn loss. Physico-electrochemical characteristics of the EMD produced from the purified MnSO4 solutions obtained by using CaO, MgO and NaOH for Fe removal during stage I purification and subsequent stage II purification of other impurities as sulphides was investigated and the discharge capacities of the EMD samples were found to be 267, 260 and 250 mAhg− 1 respectively.

Additive action on boehmite precipitation in sodium aluminate solution

Dalton Transactions, 2010

Korean Journal of Chemical Engineering, 2012

The paper deals with the extraction of copper from the deposited material of the liner of the ele... more The paper deals with the extraction of copper from the deposited material of the liner of the electrostatic precipitator (ESP) of the copper smelter plant. These precipitates of ESP liner (ESP dust) generally contain mixed phases of copper and arsenic. An attempt is made to extract copper from ESP dust, subsequently removing arsenic from the leach liquor. The ESP dust containing paramelaconite (6CuO•Cu 2 O), α-domeykite (Cu 3 As), metadomeykite (Cu 3 As), enargite (Cu 3 AsS 4) and (Cu,Fe) SO 4 •H 2 O is not a naturally occurring geological mineral; thus comparatively high acid concentration and temperature are required to break the matrix of this mixed material so as to liberate the content. The leaching efficiency of copper was 97% at 97 o C. The acid concentration of 1.5 M and pulp density of 20% was found to be optimum. The removal of arsenic as ferric arsenate was carried out in two stages: increasing the pH and precipitation of arsenic by adjusting pH of the solution and by adding ferrous sulfate and hydrogen peroxide. The optimum removal of arsenic was 95% when pH was raised to 2.35 followed by precipitation. The key progression of the process is the recovery of copper from ESP dust as well as removal of arsenic from the leach liquor.

Rare Metal Technology 2019, 2019

An integrated approach has been made to extract potassium and aluminium from a silicate mineral, ... more An integrated approach has been made to extract potassium and aluminium from a silicate mineral, i.e. nepheline syenite with 5.4% K 2 O, 19.9% Al 2 O 3 , 55.5% SiO 2. Chloridising-roasting experiments were carried using CaCl 2 at 900°C for 1 h and water leaching at ambient temperature for 1 h. The leach liquor contains impurities like Ca and Na; hence, selective extraction of potassium was carried out through precipitation using perchloric acid at freezing temperatures. XRD data of the final KCl product obtained after decomposition of KClO 4 indicated cubical crystal system and was found to be 99.5% pure. In the second stage, leaching of the residue was carried out with HCl, H 2 SO 4 and H 2 SiF 6. For selective aluminium recovery, sulphuric acid was found to be the better leachant. A 2 3 full factorial design with time, temperature and acid concentration was used. Finally, aluminium sulphate crystals were produced from the leach liquor after removing iron through pH adjustment.