scholarly journals Cleaner Production of Chromium Oxide from Low Fe(II)-Chromite

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 460 ◽  
Author(s):  
Qing Zhao ◽  
Chengjun Liu ◽  
Peiyang Shi ◽  
Lifeng Sun ◽  
Maofa Jiang ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Sulfuric Acid Concentration ◽  
Acid Leaching ◽  
Processing Parameters ◽  
Dissolution Behavior ◽  
Optimum Process ◽  
Process Conditions ◽  
Box Behnken Design ◽  
Functional Relationships ◽  
Leaching Process

Sulfuric acid-based leaching is a promising cleaner method to produce chromium salts, but its feasibility for treating low Fe(II)-chromite still remains to be proven. A Box–Behnken design (BBD)-based set of experiments for sulfuric acid leaching of low Fe(II)-chromite was utilized in this work for generating an experimental dataset for revealing the functional relationships between the processing parameters and the extraction yields of Cr and Fe. The dependent variables were found to exhibit strong intercorrelations and the models developed on the basis of statistical criteria showed excellent prediction accuracy. The optimum process conditions of leaching treatment were found to be a temperature of 176 °C, a dichromic acid/chromite mass ratio of 0.12, and a sulfuric acid concentration of 81%. Furthermore, the dissolution behavior of chromite in the leaching process and the effect of dichromic acid were experimentally investigated. It was found that the decomposition efficiency was highly dependent on the Fe(II) content of chromite, and that the dichromic acid acted both as an oxidant and a catalyst in the leaching process. On the basis of the results of this study, a novel process for treating low-Fe(II) chromite was proposed.

scholarly journals Intensification of Sulfuric Acid Leaching of Altered Ilmenite via Adding Fluoride Activator

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1922
Author(s):  
Anastasiia V. Dubenko ◽  
Mykola V. Nikolenko ◽  
Oleksandr O. Pasenko ◽  
Andrii Kostyniuk ◽  
Blaž Likozar
Keyword(s):  
Sulfuric Acid ◽  
Sulfuric Acid Concentration ◽  
Reaction Medium ◽  
Acid Leaching ◽  
Raw Material ◽  
Molar Ratio ◽  
Main Stage ◽  
Sulfuric Acid Leaching ◽  
Fluoride Ions ◽  
Leaching Process

A new method of altered ilmenite processing has been studied. In this method, sulfuric acid is used as the reaction medium of the process, and fluoride ions are activators of the dissolving process of the rutile part of the ore raw material. The regression model of the sulfate–fluoride leaching process was developed and analyzed by using the response surface method of 23 matrix. The obtained model is adequate and well describes the studied process. The influence of Ti:F molar ratio, temperature, and sulfuric acid concentration on the leaching process are investigated in this work in order to optimize the studied process. It is experimentally proved that leaching at temperatures above 100 °C, at a molar ratio of Ti:F of more than 1:2, and the use of solutions of sulfuric acid with concentrations of more than 85 wt.% is not optimal because the extraction degree of titanium is reduced. The intensification of the process of sulfuric acid leaching by dividing the main stage of chemical dissolution of ilmenite into two stages was proposed. This method allows to leach up to 95.9% of titanium, which is 1.6–1.9 times higher in comparison with the classical technology of leaching altered ilmenite.

scholarly journals Thermodynamics and Kinetics of Sulfuric Acid Leaching Transformation of Rare Earth Fluoride Molten Salt Electrolysis Slag

2021 ◽  
Vol 9 ◽  
Author(s):  
Lijie Chen ◽  
Jiacong Xu ◽  
Xiaoqiang Yu ◽  
Lei Tian ◽  
Ruixiang Wang ◽  
...  
Keyword(s):  
Rare Earth ◽  
Sulfuric Acid ◽  
Molten Salt ◽  
Acid Concentration ◽  
Sulfuric Acid Concentration ◽  
Acid Leaching ◽  
Sulfuric Acid Leaching ◽  
Rare Earth Fluoride ◽  
Leaching Process ◽  
Earth Fluoride

Rare earth element recovery in molten salt electrolysis is approximately between 91 and 93%, whereof 8% is lost in waste molten salt slag. Presently, minimal research has been conducted on the technology for recycling waste rare earth molten salt slag, which is either discarded as industrial garbage or mixed with waste slag into qualified molten salt. The development of a new approach toward the effective treatment of rare earth fluoride molten salt electrolytic slag, which can recycle the remaining rare earth and improve the utilization rate, is essential. Herein, weak magnetic iron separation, sulfuric acid leaching transformation, water leaching, hydrogen fluoride water absorption, and cycle precipitation of rare earth are used to recover rare earth from their fluoride molten salt electrolytic slag, wherein the thermodynamic and kinetic processes of sulfuric acid leaching transformation are emphatically studied. Thermodynamic results show that temperature has a great influence on sulfuric acid leaching. With rising temperature, the equilibrium constant of the reaction gradually increases, and the stable interval of NdF3 decreases, while that of Nd3+ increases, indicating that high temperature is conducive to the sulfuric acid leaching process, whereof the kinetic results reveal that the activation energy E of Nd transformation is 41.57 kJ/mol, which indicates that the sulfuric acid leaching process is controlled by interfacial chemical reaction. According to the Nd transformation rate equation in the sulfuric acid leaching process of rare earth fluoride molten salt electrolytic slag under different particle size conditions, it is determinable that with the decrease of particle size, the reaction rate increases accordingly, while strengthening the leaching kinetic process. According to the equation of Nd transformation rate in the sulfuric acid leaching process under different sulfuric acid concentration conditions, the reaction series of sulfuric acid concentration K = 6.4, which is greater than 1, indicating that increasing sulfuric acid concentration can change the kinetic-control region and strengthen the kinetic process.

Study on the Hydrolysis of Corn Stalk and Photosynthetic Bacteria Group Fermentation Hydrogen Production

2011 ◽  
Vol 194-196 ◽  
pp. 2187-2190
Author(s):  
Bao Chen Cui ◽  
Guo Xin Zhang ◽  
Bo Hou ◽  
Jing Yan Zhao ◽  
Rui Li
Keyword(s):  
Sulfuric Acid ◽  
Hydrogen Production ◽  
Acid Concentration ◽  
Photosynthetic Bacteria ◽  
Sulfuric Acid Concentration ◽  
Optimum Process ◽  
Process Conditions ◽  
Hydrogen Yield ◽  
Corn Stalk ◽  
Hydrolysis Temperature

Hydrogen production of photosynthetic bacteria group (PSBG) was studied using corn stalk hydrolyzate as hydrogen production substrate. The effects of sulfuric acid concentration, hydrolysis pH values and hydrolysis temperature on hydrogen production were investigated. The optimum process conditions were as follows: the sulfuric acid concentration was 1%, hydrolysis pH value was 6.0 and the hydrolysis temperature was 110°C , respectively. Three hydrolyzate detoxification methods were compared. The method of calcium hydroxide obtained the optimal detoxification effect and the maximum hydrogen yield was 472 mL H2/ (L-medium).

scholarly journals Performance of Sulfuric Acid Leaching of Titanium from Titanium-Bearing Electric Furnace Slag

2016 ◽  
Vol 5 (4) ◽  
pp. 1 ◽  
Author(s):  
XiaoMing Qu ◽  
YuFeng Guo ◽  
FuQiang Zheng ◽  
Tao Jiang ◽  
GuanZhou Qiu
Keyword(s):  
Sulfuric Acid ◽  
Electric Furnace ◽  
Sulfuric Acid Concentration ◽  
Acid Leaching ◽  
Sulfuric Acid Leaching ◽  
Water Leaching ◽  
Experimental Conditions ◽  
Leaching Process ◽  
Leaching Residue ◽  
Furnace Slag

<p class="1Body">The sulfuric acid leaching of titanium from titanium-bearing electric furnace slag (TEFS) was investigated under different experimental conditions. In the sulfuric acid leaching process, the M<sub>x</sub>Ti<sub>3-x</sub>O<sub>5</sub>(0≤x≤2) and diopside could react with sulfuric acid. The optimum conditions of sulfuric acid leaching process were particle size at &lt; 0.045mm, sulfuric acid concentration at 90 wt.%, acid/slag mass ratio at 1.6:1, feeding temperature at 120 °C, reaction temperature at 220 °C, reaction time at 120minute, curing at 200°C for 120 minute. The [TiO<sub>2</sub>] concentration of the water leaching was 150 g/L, and leaching temperature at 60℃for 120 minute. Ti extraction could reach 84.29 %. F of titanium-bearing solution was 2.15, and the Ti<sup>3+</sup>/TiO<sub>2</sub> of the titanium-bearing solution was 0.068. The TiO<sub>2</sub> content of the leaching residue was 18.32 wt.%. The main mineral phases of the leaching residue were calcium sulphate, spinel, diopside and little M<sub>x</sub>Ti<sub>3-x</sub>O<sub>5</sub>.</p>

Direct Acid Leaching of Vanadium from Stone Coal

2017 ◽  
Vol 36 (9) ◽  
pp. 877-883 ◽  
Author(s):  
Bo Zhang ◽  
Zhaoguo Gao ◽  
Hongzhao Liu ◽  
Wei Wang ◽  
Yaohua Cao
Keyword(s):  
Sulfuric Acid ◽  
Acid Leaching ◽  
Influential Factors ◽  
Process Conditions ◽  
Stone Coal ◽  
Leaching Process ◽  
Maximum Value ◽  
Orthogonal Experiments ◽  
Counter Current ◽  
Leaching Efficiency

AbstractThis paper focused on optimizing the process conditions of direct acid leaching process to enhance the leaching efficiency of leaching vanadium from the stone coal. Orthogonal experiments and single factor experiments were conducted to investigate the effect of the influential factors of direct acid leaching on vanadium leaching ratio. The results showed that the vanadium leaching ratio reached the maximum value of 89.22 % under the optimal process conditions of CaF2 dosage 5 mass%, H2SO4 dosage 40 mass%, leaching temperature 95 °C and leaching time 10 h. Furthermore, the reaction mechanisms of the main influencing factors were analyzed. Finally, the two-stage counter-current leaching process was adopted to decrease the consumption of sulfuric acid and neutralizer, and the results indicated that the consumption of sulfuric acid decreased 12.50 % as well as neutralizer decreased 35.80 %.

scholarly journals Recovery of Magnesium from Ferronickel Slag to Prepare Magnesium Oxide by Sulfuric Acid Leaching

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1375
Author(s):  
Juan Yang ◽  
Xuqin Duan ◽  
Lingchuan Liu ◽  
Huifen Yang ◽  
Xiaocui Jiang
Keyword(s):  
Sulfuric Acid ◽  
Magnesium Oxide ◽  
Sulfuric Acid Concentration ◽  
Acid Leaching ◽  
Magnesium Carbonate ◽  
Leaching Rate ◽  
Sulfuric Acid Leaching ◽  
Leaching Process ◽  
Interactive Behavior ◽  
Ferronickel Slag

This paper provides a technical approach for efficiently recovering Mg from ferronickel slag to produce high-quality magnesium oxide (MgO) by using the sulfuric acid leaching method under atmospheric pressure. The leaching rate of magnesium is 84.97% after a typical one-step acid leaching process, which is because Mg in FNS mainly exists in the forsterite (Mg2SiO4) phase, which is chemically stable. In order to increase the leaching rate, a two-step acid leaching process was proposed in this work, and the overall leaching rate reached up to 95.82% under optimized conditions. The response surface methodology analysis for parameter optimization and Mg leaching rules revealed that temperature was the most critical factor affecting the Mg leaching rate when the sulfuric acid concentration was higher than 2 mol/L, followed by acid leaching time. Furthermore, interactive behavior also existed between the leaching temperature and leaching time. The leaching kinetics of magnesium from FNS followed a shrinkage-nuclear-reaction model with composite control, which were chemically controlled at lower temperatures and diffusion controlled at higher temperatures; the corresponding apparent activation energy was 19.57 kJ/mol. The leachate can be used to obtain spherical-like alkali magnesium carbonate particles with diameters of 5–10 μm at 97.62% purity. By using a further calcination process, the basic magnesium carbonate can be converted into a light magnesium oxide powder with a particle size of 2–5 μm (MgO content 94.85%), which can fulfill first-level quality standards for industrial magnesium oxide in China.

scholarly journals Study on Ultrasonically-Enhanced Sulfuric Acid Leaching of Nickel from Nickel-Containing Residue

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 810
Author(s):  
Zhanyong Guo ◽  
Ping Guo ◽  
Guang Su ◽  
Fachuang Li
Keyword(s):  
Sulfuric Acid ◽  
Acid Leaching ◽  
Ultrasonic Waves ◽  
Sulfuric Acid Leaching ◽  
Solid Product ◽  
Leaching Process ◽  
Diffusion Controlled ◽  
Extraction Degree ◽  
Ultrasonic Conditions ◽  
Complex Nickel

In this paper, nickel-containing residue, a typical solid waste produced in the battery production process, was used to study the cavitation characteristics of ultrasonic waves in a liquid–solid reaction. The ultrasonically-enhanced leaching technology for multicomponent and complex nickel-containing residue was studied through systematic ultrasonic-conventional comparative experiments. An ultrasonic leaching kinetics model was established which provided reliable technological guidance and basic theory for the comprehensive utilization of nickel-containing residue. In the study, it was found that ultrasonically-enhanced leaching for 40 min obtained the same result as conventional leaching for 80 min, and the Ni extraction degree reached more than 95%. According to the kinetic fitting of the leaching process, it was found that the sulfuric acid leaching process belonged to the diffusion-controlled model of solid product layers under conventional and ultrasonic conditions, and the activation energy of the reaction was Ea1 = 17.74 kJ/mol and Ea2 = 5.04 kJ/mol, respectively.

scholarly journals Extraction of Ta and Nb from a Coltan Bearing Ore by Means of Ammonium Bifluoride Fluorination and Sulfuric Acid Leaching

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1392
Author(s):  
Alidor Shikika ◽  
Francois Zabene ◽  
Fabrice Muvundja ◽  
Mac C. Mugumaoderha ◽  
Julien L. Colaux ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Acid Leaching ◽  
Environmental Benefits ◽  
Process Conditions ◽  
Sulfuric Acid Leaching ◽  
Mechanical Agitation ◽  
Ammonium Bifluoride ◽  
Novel Approach ◽  
Pre Treatment ◽  
Subsequent Acid

A novel approach for Ta and Nb extraction consisting of the pre-treatment of a coltan-bearing ore with an ammonium bifluoride sub-molten salt and subsequent acid leaching has been studied. The effects from ore granulometry, ammonium bifluoride (ABF) to ore mass ratio, temperature and duration of fluorination on the degree of Ta and Nb extraction were examined. The ABF to ore ratio and process temperature were found to have the most pronounced impact on extraction efficiency. The following optimal process conditions were determined: ore granulometric fraction (−75 + 45 µm), ABF-ore (5/1), fluorination temperature (200 °C) and fluorination time (2.5 h). Maintaining these parameters enabled about 94% of Ta and 95% of Nb to be brought into solution during the sulfuric-acid-leaching stage. A comparison of the proposed method with previously reported studies suggests that due to the effects of mechanical agitation and the recirculation of the HF-containing gaseous phase back into the process, the dosage rate of ABF at the fluorination stage could be reduced significantly without sacrificing the overall recovery of Ta and Nb. In such a way, the approach could offer added environmental benefits since release of fluoride-containing effluents into the environment could be limited.

Uranium Bioleaching from Low Grade Ore

2020 ◽  
Vol 989 ◽  
pp. 559-563
Author(s):  
Ashimkhan T. Kanayev ◽  
Khussain Valiyev ◽  
Aleksandr Bulaev
Keyword(s):  
Sulfuric Acid ◽  
Acid Mine Drainage ◽  
Mine Drainage ◽  
Sulfuric Acid Concentration ◽  
Acid Leaching ◽  
Leach Solution ◽  
Low Grade ◽  
Bacterial Cells ◽  
Acid Mine

The goal of the present work was to perform bioleaching of uranium from low grade ore from Vostok deposit (Republic of Kazakhstan), which was previously subjected to long-term acid leaching. The ore initially contained from 0.15 to 0.20% of uranium in the form of uraninite, but ore samples used in the study contained about 0.05% of uranium, as it was exhausted during acid leaching, and uranium was partially leached. Representative samples of ore were processed in 1 m columns, leach solutions containing 5, 10, 20 g/L of sulfuric acid and bacterial cells (about 104) were percolated through the ore. Leaching was performed at ambient temperature for 70 days. In one of the percolators, the leaching was performed with leaching solution containing 10 g/L of H2SO4, cells of A. ferrooxidans, and 0.5 g/L of formaldehyde. Leaching with the solution containing 5, 10, and 20 g/L of sulfuric acid made it possible to extract 50, 53, and 58% of uranium. Addition of formaldehyde in leach solution led to the decrease in uranium extraction extent down to 37%. Thus, the results of the present work demonstrated that uranium ore exhausted during long-term acid leaching may be successfully subjected to bioleaching, that allows extracting residual quantities of uranium. Leaching rate of uranium from exhausted ore depended on both sulfuric acid concentration and microbial activity of bacteria isolated from acid mine drainage, formed on uranium deposit. In the same time, acid mine drainage may be used as a source of inoculate, to start bioleaching process.

Experimental Study on Sulfuric Acid Leaching Behavior of Chromite with Different Temperature

2011 ◽  
Vol 361-363 ◽  
pp. 628-631 ◽  
Author(s):  
Cheng Jun Liu ◽  
Jie Qi ◽  
Mao Fa Jiang
Keyword(s):  
Sulfuric Acid ◽  
Acid Leaching ◽  
Raw Material ◽  
Leaching Rate ◽  
Sulfuric Acid Leaching ◽  
Leaching Process ◽  
Pollution Problem ◽  
Environmental Pollution Problem ◽  
Leaching Solution ◽  
Leaching Residue

Utilizing Pakistan chromite as raw material, the rapid leaching of chromium and iron could be realized by the sulfuric acid leaching process on the condition of atmospheric pressure and the addition of oxidant A. And the leaching rate of chromium and iron would be 98.5% and 71.9%, respectively. The sulfuric acid leaching processes with different temperature were systematically studied by chemical analysis and phase analysis. The results showed that, with the increase of reaction temperature, the leaching rate of chromium would increase gradually, but the leaching rate of iron increased at first and then decreases and reached its maximum at 140°C. When the temperature > 160°C, the phases of the leaching residue were magnesium iron silicate and a few of silica, no chromohercynite, chrompicotite and magnesioferrite existed in the chromite. The leaching solution of sulfuric acid leaching process could be used for preparing the basic chrome sulfate, and there is no Cr6+ in the leaching residue and solution. The results would provide theoretical guidance for solving environmental pollution problem of Cr6+ in traditional chromate production process.

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