scholarly journals An Eco-Friendly Acid Leaching Strategy for Dealkalization of Red Mud by Controlling Phase Transformation

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 580
Author(s):  
Jiaming Wu ◽  
Tianyu Lei ◽  
Beibei Wang ◽  
Shuwei Ma ◽  
Yulong Lin ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Red Mud ◽  
High Selectivity ◽  
Phase State ◽  
Acid Leaching ◽  
Secondary Pollution ◽  
Valuable Metals ◽  
Valuable Element ◽  
Alkaline Component ◽  
Roasting Temperature

The alkaline components in red mud represent one of the crucial factors restricting its application, especially for the construction and building industry. The phase state of alkaline components has a significant influence on the dealkalization of red mud. In this work, an environmentally friendly acid leaching strategy is proposed by controlling the phase transformation of red mud during active roasting pretreatment. With a moderate roasting temperature, the alkaline component is prevented from converting into insoluble phases. After acid leaching with a low concentration of 0.1 M, a high dealkalization rate of 92.8% is obtained. Besides, the leachate is neutral (pH = 7) and the valuable metals in red mud are well preserved, manifesting a high selectivity and efficiency of diluted acid leaching. The calcination experiment further confirms the practicability of the strategy in the construction field, where the cementitious minerals can be formed in large quantities. Compared with the traditional acid leaching routes, the diluted acid leaching strategy in this work is acid saving with low valuable element consumption. Meanwhile, the secondary pollution issue can be alleviated. Hence, the findings in this work provide a feasible approach for the separation and recovery of alkali and resource utilization of red mud.

scholarly journals Recovery of Zinc and Silver from Zinc Acid-Leaching Residues with Reduction of Their Environmental Impact Using a Novel Water Leaching-Flotation Process

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 586
Author(s):  
Yunpeng Du ◽  
Xiong Tong ◽  
Xian Xie ◽  
Wenjie Zhang ◽  
Hanxu Yang ◽  
...  
Keyword(s):  
Hazardous Waste ◽  
Acid Leaching ◽  
Copper Recovery ◽  
Water Leaching ◽  
Flotation Process ◽  
Metal Levels ◽  
Valuable Metals ◽  
Leaching Experiments ◽  
Zinc Hydrometallurgy ◽  
Poor Stability

Zinc-leaching residue (ZLR) is a strongly acidic hazardous waste; it has poor stability, high heavy metal levels, and releases toxic elements into the environment. ZLR has potential as a valuable resource, because it contains elevated levels of zinc and silver. In this paper, the recovery of zinc (Zn) and silver (Ag) from ZLR wastes from zinc hydrometallurgy workshops using water leaching followed by flotation was studied. During water leaching experiments, the zinc and copper recovery rates were 38% and 61%, respectively. Thereafter, various flotation testing parameters were optimized and included grinding time, reagent dosages, pulp density, flotation time, and type of adjuster. Experimental results demonstrated this flotation method successfully recycled Ag and Zn. A froth product containing more than 9256.41 g/t Ag and 12.26% Zn was produced from the ZLR with approximately 80.32% Ag and 42.88% Zn recoveries. The toxicity characteristic leaching procedure (TCLP) results indicated the water-leaching flotation process not only recycled valuable metals such as zinc and silver in zinc-containing hazardous wastes but lowered the hazardous waste levels to those of general wastes and recycled wastes in an efficient, economical, and environmentally friendly way.

Leaching Behavior Analysis of Valuable Metals from Lithium-Ion Batteries Cathode Material

2018 ◽  
Vol 775 ◽  
pp. 419-426 ◽  
Author(s):  
Wei Sheng Chen ◽  
Hsing Jung Ho
Keyword(s):  
Cathode Material ◽  
Lithium Ion Batteries ◽  
Acid Leaching ◽  
Lithium Ion ◽  
Activation Energies ◽  
Mass Ratio ◽  
Solid Mass ◽  
Environmental Technology ◽  
Valuable Metal ◽  
Valuable Metals

The paper concerns an approach about using environmental technology and hydrometallurgical process to the recovery of valuable metal from waste cathode material produced during the manufacture of lithium-ion batteries. It is noteworthy that the content of nickel, manganese and cobalt from cathode material are in the extraordinary large proportion. In the acid leaching step, the essential effects of H2SO4 concentration, H2O2 concentration, leaching time, liquid-solid mass ratio and reaction temperature with the leaching percentage were investigated. The cathode material was leached with 2M H2SO4 and 10 vol.% H2O2 at 70 °C and 300 rpm using a liquid-solid mass ratio of 30 ml/g and the leaching efficiency of cobalt was 98.5%, lithium was 99.8%, nickel was 98.6% and manganese was 98.6% under optimum conditions. Kinetic study demonstrates the activation energies for those analyzed metals with Arrhenius equation and manifests the data with hybrid reaction control mechanism. The process was proved from activation energies ranged from 27.79 to 47.25 kJ/mol. Finally, the valuable metals will be leached in sulfuric acid effectively.

Effect of Cutting Temperature on Phase Transformation in Cutting of NiTi Alloy

2020 ◽  
Author(s):  
Hao Yang ◽  
Katsuhiko Sakai ◽  
Hiroo Shizuka ◽  
Kunio Hayakawa ◽  
Tetsuo Nagare
Keyword(s):  
Phase Transformation ◽  
Phase State ◽  
Niti Alloy ◽  
Cutting Temperature ◽  
Cutting Speed ◽  
Cutting Process ◽  
Maximum Temperature ◽  
Machined Surface ◽  
Speed Condition ◽  
Work Material

Abstract In this study, the effect of cutting temperature on phase transformation in cutting of room temperature austenitic NiTi alloy was investigated by X-ray diffraction (XRD) and temperature measurements. Results from XRD reveals that after cutting process, the phase state of work material near the machined surface transformed from austenite to martensite at relatively low cutting speed conditions while the phase state of work material did not undergo any form of transformation at the highest cutting speed condition. Temperature measurement results measured with temperature indicating paint showed that the maximum temperature of work material near the machined surface in cutting process exceeded the Md temperature at the highest cutting speed condition. However, there was no phase transformation observed in cutting chips after cutting at all cutting speed conditions as the temperature of cutting chips was much higher than the Md temperature under all cutting speed conditions.

scholarly journals Denitrification performance of rare earth tailings-based catalysts

2019 ◽  
Vol 8 (1) ◽  
pp. 865-872 ◽  
Author(s):  
Zhenfeng Wang ◽  
Yanan Huang ◽  
Huijuan Luo ◽  
Zhijun Gong ◽  
Kai Zhang ◽  
...  
Keyword(s):  
Rare Earth ◽  
High Performance ◽  
Acid Leaching ◽  
Performance Tests ◽  
Temperature Range ◽  
Catalytically Active ◽  
Bayan Obo ◽  
Roasting Temperature ◽  
Rare Earth Tailings ◽  
Active Substances

Abstract Rare earth tailings from the Bayan Obo mine are rich in rare earth, iron, and other catalytically active substances. In this study, Na2CO3 and Ca(OH)2 were mixed with rare earth tailings, roasted, and the tailings modified by HCl-citric acid leaching and pickling to prepare high-performance rare earth tailings-based denitrification catalysts. Denitrification performance tests show that, in the temperature range 700°C~900°C, the alkali and acid co-processed modified tailings sample gave the best catalytic denitrification performance. XRD, SEM, and H2-TPR analyses show that, compared with raw ore samples, Fe activity sites increased after alkali and acid co-treatment. Cracks and holes appeared on the surface of the sample, and the reduction temperature range was broadened. XPS analysis showed that Fe coexisted in the forms Fe2+ and Fe3+, and Ce in the forms Ce3+ and Ce4+. At a rare earth tailings microwave roasting temperature of 500°C, NO concentration of 500 ppm, CO/NO ratio 4:1, and reaction temperature of 900°C, the denitrification efficiency of the catalyst was optimal, at up to 96.2%. In this study, a relatively green and pollution-free method was used to prepare catalysts, which can provide reference for solving the problem of rare earth tailings accumulation.

scholarly journals Influence of Hydrofluoric Acid Leaching and Roasting on Mineralogical Phase Transformation of Pyrite in Sulfidic Mine Tailings

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 513 ◽  
Author(s):  
Babak Koohestani ◽  
Ahmad Khodadadi Darban ◽  
Pozhhan Mokhtari ◽  
Esmaeel Darezereshki ◽  
Erol Yilmaz ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Phase Transformation ◽  
Iron Oxides ◽  
Mine Tailings ◽  
Hydrofluoric Acid ◽  
Surface Characterization ◽  
Acid Leaching ◽  
Roasting Process ◽  
Pyrite Content ◽  
Mineralogical Phase

Under the oxidative roasting process, pyrite, as a major mineral in sulfidic mine tailings, can transform to iron oxides. Generated iron oxides, if exhibiting enough magnetic properties, can be recovered via magnetic separation resulting in partial mine tailings valorization. However, due to the presence of various minerals and sintering possibility, it is advantageous to remove impurities and increase the pyrite content of mine tailings prior to the roasting procedure. In this case, hydrofluoric acid that has no influence on pyrite can be used to leach most inorganic minerals, including aluminosilicates. Therefore, this study investigated and compared the influence of the roasting process with and without hydrofluoric acid leaching pretreatment on mineralogical phase transformation of pyrite and magnetic properties of thermally generated minerals. Several tests and analyses were performed to study mineralogical phase transformation, morphology, elemental composition, surface characterization, and magnetic properties. Results of this study indicated that without acid leaching pretreatment, pyrite was mainly transformed to hematite. However, via acid leaching, fluorine, as a more electronegative element over oxygen, entered the compound and neglected the role of oxygen in thermal oxidation, instead reducing sulfur content of pyrite to only form pyrrhotite.

Study on Recovering Zinc from Gossan

2012 ◽  
Vol 454 ◽  
pp. 329-332 ◽  
Author(s):  
Jin Lin Yang ◽  
Shao Jian Ma ◽  
Wei Mo ◽  
Jin Peng Feng ◽  
Xiu Juan Su ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Sulfuric Acid Concentration ◽  
Acid Leaching ◽  
Leaching Rate ◽  
Sulfuric Acid Leaching ◽  
Alkaline Leaching ◽  
Physical Separation ◽  
Xrd Pattern ◽  
Diffraction Peaks ◽  
Roasting Temperature

In this paper, the conventional physical separation method such as flotation, gravity separation, magnetic separation, alkaline leaching and sulfuric acid leaching were studied. The effects of grinding fineness, amount of agent, magnetic intensity, roasting temperature, roasting time, the leaching agent and leaching time on the leaching of zinc were investigated, respectively. The results show that the leaching rate of zinc is below 50% in the conventional alkaline leaching, and the leaching rate of zinc is below 85% and the leaching rate of iron is above 35% in sulfuric acid leaching. Compared with XRD pattern of the raw ore, the different diffraction peaks of smithsonite is off in alkaline leaching products. In sulfuric acid leaching, the different diffraction peaks of smithsonite are off in the leaching products when sulfuric acid concentration is less than 60 g/L. After 60 g/L, the different diffraction peaks of smithsonite and siderite are off in the leaching products.

Recovery of Copper and Cobalt from Spent Aerospace Material with Pollution-Free Oxidant

2012 ◽  
Vol 476-478 ◽  
pp. 357-360 ◽  
Author(s):  
Yue Bin Xiao ◽  
Xue Jiao Zhou ◽  
Lei Cao ◽  
Ya Gao ◽  
Da Liu ◽  
...  
Keyword(s):  
Acid Leaching ◽  
Agitation Speed ◽  
Temperature Reaction ◽  
Initial Concentration ◽  
Solid Ratio ◽  
Aerospace Material ◽  
Valuable Element ◽  
C 30 ◽  
Optimized Conditions ◽  
Free Oxidation

The acid leaching of spent aerospace material with pollution-free oxidation is discussed. Effect of parameters including initial concentration of hydrochloric acid solution, leaching temperature, reaction time, agitation speed, liquid to solid ratio and concentration of oxidant on valuable element extractions are determined, the optimized conditions are 6 M, 60 °C, 30 min, 250 r/min, 6:1 and 0.0378 mol•L-1•min-1, respectively. The comprehensive results of experiments show that the extracting efficiency of Co and Cu are over 83% and 98% respectively when optimized conditions were adopted.

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