scholarly journals Recovery of Tantalum and Manganese from Epoxy-Coated Solid Electrolyte Tantalum Capacitors through Selective Leaching and Chlorination Processes

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 656
Author(s):  
Wei-Sheng Chen ◽  
Chih-Yuan Hsiao ◽  
Cheng-Han Lee
Keyword(s):  
Reaction Time ◽  
Hydrochloric Acid ◽  
Solid Electrolyte ◽  
Epoxy Resin ◽  
Selective Leaching ◽  
Ferrous Chloride ◽  
Electronic Products ◽  
Solid Ratio ◽  
Chlorination Process ◽  
Acid Type

Electronic products are ever growing in popularity, and tantalum capacitors are heavily used in small electronic products. Spent epoxy-coated solid electrolyte tantalum capacitors, containing about 22 wt.% of tantalum and 8 wt.% of manganese, were treated with selective leaching by hydrochloric acid and chlorination after removing the epoxy resin, and the products converted, respectively, to Mn(OH)2 and TaCl5. The effects of acid type, acid concentration, liquid–solid ratio, and reaction time were investigated to dissolve the manganese. The optimal selective leaching conditions were determined as 3 mol/L of HCl, 40 mL/g at 25 °C for 32 min. Next, residues of selective leaching after washing and drying were heated with ferrous chloride to convert to pure TaCl5. Mixing 48 wt.% of chloride and 52 wt.% of residues for a total of 5 g was conducted to complete the chlorination process in the tube furnace at 450 °C for 3 h. A total of 2.35 g of Ta was collected and the recovery of Ta achieved 94%. Finally, Mn(OH)2 and TaCl5 were separated and purified as the products.

Experimental Study on Concentrating Scandium by Leaching from Associated Scandium Ore

2013 ◽  
Vol 734-737 ◽  
pp. 1033-1036
Author(s):  
Gui Fang Zhang ◽  
Peng Yan ◽  
Qing Rong Yang
Keyword(s):  
Experimental Study ◽  
Particle Size ◽  
Hydrochloric Acid ◽  
Acid Concentration ◽  
Hydrochloric Acid Concentration ◽  
Leaching Rate ◽  
Optimal Conditions ◽  
Research Results ◽  
Solid Ratio ◽  
Leaching Residue

Based on the benefication of the complex silicate ore containing scandium, the research about aid-leaching agent used in the leaching of the scandium concentrate was been conducted. And the suitable leaching agent and aid-leaching agent which the useful ions entered into leaching liquid and the harmful ions were kept in leaching residue were been found according to the experiment results. For the scandium of sample existed various complex silicate ore as isomorphism form, the research has adopted hydrochloric acid with aid-leaching agent to dissociate the silicate ore and make scandium entering into solution. The research results has shown that the scandium leaching rate could reach 92.06% under the optimal conditions which the hydrochloric acid concentration is 22.8%, the dosage of aid leaching agent is 6%, liquid solid ratio is 4:1, particle size of leaching material totally is less than 0.15mm and leaching time is 8h.

Experimental Study of Purifying Precipitated Silica Produced from Yellow Phosphorus Slag

2012 ◽  
Vol 455-456 ◽  
pp. 503-506 ◽  
Author(s):  
Guo Bing Li ◽  
Hai Lin ◽  
Yan Li Ma ◽  
Yi Su
Keyword(s):  
Experimental Study ◽  
Nitric Acid ◽  
Reaction Time ◽  
Nitric Acid Concentration ◽  
Acid Leaching ◽  
Quality Requirements ◽  
Solid Ratio ◽  
Precipitated Silica ◽  
Yellow Phosphorus ◽  
Fe Content

When precipitated silica was prepared from yellow phosphorus slag by the phosphoric acid leaching, the Fe content can not meet the quality requirements of the product. This article indicates the method of purifying precipitated silica with nitric acid solution, which may decrease the Fe content to about 0.02%. The purification optimum technical conditions are: the nitric acid concentration 8%, reaction time 2.0 hours, reaction temperature 343.15K, fluid solid ratio 4:1, stirring speed 300 rpm.

Experimental Researches on the Preparation of High-Efficient Active Floridin by Mixed Acids

2012 ◽  
Vol 510 ◽  
pp. 713-718
Author(s):  
Ming Yong Shu ◽  
Hai Ying Yin ◽  
Guang Hui Liu
Keyword(s):  
Reaction Time ◽  
Reaction Temperature ◽  
Volume Ratio ◽  
Raw Material ◽  
Activation Effect ◽  
Solid Ratio ◽  
High Efficient ◽  
Main Factors ◽  
Experimental Researches ◽  
Mixed Acids

Taking ca-bentonite as the raw material, the activation effect of active floridin prepared by mixed acids of H2SO4, HCl and C2H2O4 is studied. The research results indicate that the main factors influencing the activity and decolorization ratio of floridin include volume ratio of mixed acids, liquid-to-solid ratio, reaction temperature and reaction time. When the volume ratio of mixed acids H2SO4: HCl: C2H2O4=5:5:1, liquid-to-solid ratio =4:1, reaction temperature 80 and reaction time 4h, it is possible to prepare high-efficient active floridin.

scholarly journals Highly Selective Synthesis of Chlorophenols under Microwave Irradiation

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Yawen Xiong ◽  
Hongdong Duan ◽  
Xia Meng ◽  
Zhaoyun Ding ◽  
Weichun Feng
Keyword(s):  
Reaction Mechanism ◽  
Reaction Time ◽  
Hydrochloric Acid ◽  
Microwave Irradiation ◽  
High Efficiency ◽  
Selective Synthesis ◽  
Conversion Rates ◽  
Electron Donating Groups ◽  
Electron Transfers ◽  
Excellent Selectivity

Oxychlorination of various phenols is finished in 60 minutes with high efficiency and perfect selectivity under microwave irradiation. These reactions adopt copper(II) chloride (CuCl2) as the catalyst and hydrochloric acid as chlorine source instead of expensive and toxic ones. Oxychlorination of phenols substituted with electron donating groups (methyl, methoxyl, isopropyl, etc.) atortho-andmeta-positions is accomplished with higher conversion rates, lower reaction time, and excellent selectivity. A proposed reaction mechanism is deduced; one electron transfers from CuCl2to phenol followed by the formation of tautomeric radical that can be rapidly captured by chlorine atom and converts intopara-substituted product.

Modification of Coal Tar Pitch to Reduce the Carcinogenic Polycyclic Aromatic Hydrocarbons

2013 ◽  
Vol 295-298 ◽  
pp. 3098-3103 ◽  
Author(s):  
De Min He ◽  
Jun Guan ◽  
Di Wu ◽  
Shu Chang Zhao ◽  
Qiu Min Zhang
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Reaction Time ◽  
Epoxy Resin ◽  
Aromatic Hydrocarbons ◽  
Coal Tar ◽  
Coal Tar Pitch ◽  
Temperature Reaction ◽  
Polycyclic Aromatic ◽  
Soft Point

This research investigated on reducing carcinogenic polycyclic aromatic hydrocarbons(PAHs),especially benzo[a]pyrene (BaP) in coal tar pitch by modifying with the two selected modifiers: Paraformaldehyde and Epoxy Resin. The reaction emphasis on the change of temperature, reaction time and the quantity of the modifiers. The results indicated that Paraformaldehyde and Epoxy Resin could decrease the PAHs content greatly. The BaP decreasing rate reached 75.86% and 53.45% respectively. And the BaP equivalency content of the pitch decreased from 2.94% to 1.41% and 1.47% respectively. The properties of the modified coal tar pitch, including soft point (SP), toluene insolubles (TI), quinoline insolubles (QI) have changed a lot.

scholarly journals Telomerization of Vinyl Chloride with Chloroform Initiated by Ferrous Chloride-Dimethylacetamide under Ultrasonic Conditions

2015 ◽  
Vol 2015 ◽  
pp. 1-4
Author(s):  
Hua Qian ◽  
Hengdao Quan
Keyword(s):  
Reaction Time ◽  
Vinyl Chloride ◽  
Ultrasonic Irradiation ◽  
Catalyst System ◽  
Ferrous Chloride ◽  
Efficient Catalyst ◽  
The One ◽  
Ultrasonic Conditions

Telomerization of vinyl chloride with chloroform was investigated using ferrous chloride-dimethylacetamide system, and 42.1% yield, more than four times the one reported before, was achieved. The addition of ultrasound further improved the reaction and yield was raised to 51.9% with trace byproducts at highly reduced reaction time and temperature. Ferrous chloride-dimethylacetamide under ultrasonic irradiation acts as a very efficient catalyst system for the 1 : 1 telomerization.

A Study on Catalytic Hydrolysis of Corncob by Formic Acid

2012 ◽  
Vol 560-561 ◽  
pp. 321-324
Author(s):  
Jing Wen Xue ◽  
Zhe Wang
Keyword(s):  
Reaction Time ◽  
Hydrochloric Acid ◽  
Formic Acid ◽  
Degradation Products ◽  
Chemical Compositions ◽  
Catalytic Hydrolysis ◽  
Higher Temperature ◽  
Hydrolysis Residue ◽  
Hydrolysis Of

Corncob powder was hydrolyzed with formic acid under the catalyzation of hydrochloric acid. Sugar contents in hydrolysis liquor at different reaction time and temperature were determined. The chemical compositions in hydrolysis residue were also analyzed. Results showed that the formic acid could hydrolyze the polysaccharides in corncob and the degradation products were dissolved in hydrolysis liquor. The addition of catalytic hydrochloric acid accelerated the hydrolysis of polyose. The proper hydrolysis condition was 80°C for 3h. Lignin might undergo hydrolysis at higher temperature.

THERMAL DECARBOXYLATION OF URONIC ACIDS

1952 ◽  
Vol 30 (4) ◽  
pp. 278-290 ◽  
Author(s):  
A. S. Perlin
Keyword(s):  
Carbon Monoxide ◽  
Reaction Time ◽  
Hydrochloric Acid ◽  
Nitrogen Dioxide ◽  
Carbon Skeleton ◽  
Uronic Acids ◽  
Acid Method ◽  
Thermal Decarboxylation ◽  
Good Agreement

A novel decarboxylation of uronic acids by merely heating the material without the use of a solvent or added catalyst is described. At approximately 255 °C. decarboxylation for uronic and polyuronic acids and salts within 15 min. reaction time is nearly quantitative. Vigorous dehydration occurs simultaneously, the residue corresponding basically to a 5-carbon skeleton that contains 1.5 atoms of oxygen. Other products of the reaction are minor and include carbon monoxide, and traces of acid and oils. Sugar acids, such as gluconic and ascorbic, are not as extensively decarboxylated. The reaction is employed for analysis of several nitrogen dioxide oxidized celluloses and starches and the results are in good agreement with those given by titration and the 12% hydrochloric acid method.

scholarly journals Extraction and Back-Extraction Behaviors of La(III), Ce(III), Pr(III), and Nd(III) Single Rare Earth and Mixed Rare Earth by TODGA

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8316
Author(s):  
Lina Qiu ◽  
Jiandi Li ◽  
Weiwei Zhang ◽  
Aijun Gong ◽  
Xiaotao Yuan ◽  
...  
Keyword(s):  
Rare Earth ◽  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Liquid System ◽  
Extraction Time ◽  
Hydrochloric Acid Concentration ◽  
Back Extraction ◽  
Initial Concentration ◽  
Initial Stage ◽  
Acid Type

N,N,N′,N′-Tetraoctyl diglycolamide (TODGA), as a new extraction agent, is effective for its excellent performance and low environmental hazard, and it is very welcome for the rare earth separation process. In this paper, by controlling the extraction time, diluent type, acid type and its concentration, rare earth concentration, etc., the optimum extraction and back-extraction effects of TODGA on La(III), Ce(III), Pr(III), and Nd(III) and mixed rare earths were obtained. The experiment showed that 0.10 mol·L−1 TODGA had the best extraction effect on single rare earth under the conditions of using petroleum ether as diluent, 5 mol·L−1 nitric acid, 20 min extraction time, and 0.01 mol·L−1 rare earth. In the mixed rare earth extraction, the percentage concentrations of La(III), Ce(III), Pr(III), and Nd(III) could be achieved from 21.7%, 19.9%, 30.8%, and 22.2% at the initial stage to 90.5%, 37%, 51%, and 62% after extraction, respectively, by controlling the number of back-extraction cycles and the concentrations of hydrochloric acid and nitric acid in the back-extraction system. The TODGA–rare earth carrier system showed the best back-extraction effect when the hydrochloric acid concentration was 1 mol·L−1 and the back-extraction time was 20 min. At the same time, the mixed rare earth liquid system with low initial concentration was selected for extraction and separation of mixed rare earth. The separation effect was better, and the recovery rate was higher than that of mixed rare earth liquid system with a high initial concentration.

Sign in / Sign up

Export Citation Format

Share Document