scholarly journals Extraction of REEs (Ce, Tb, Y, Eu) from Phosphors Waste by a Combined Alkali Roasting–Acid Leaching Process

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 437
Author(s):  
Bing-Xuan He ◽  
Yong Liang ◽  
Lue-Wei Xu ◽  
Long-Bin Shao ◽  
De-Gang Liu ◽  
...  
Keyword(s):  
Rare Earth ◽  
Oxygen Concentration ◽  
Acid Leaching ◽  
Solution Concentration ◽  
Mass Ratio ◽  
Optimum Conditions ◽  
Solid Ratio ◽  
Roasting Temperature ◽  
Leaching Efficiency ◽  
Hcl Solution

Rare Earth (RE) phosphors waste contains valuable rare Earth elements (REEs), such as cerium, terbium, yttrium, and europium. In industry, the process of NaOH roasting followed by acid leaching is usually used to extract the REEs from the waste in China. Using this process, the leaching efficiencies of cerium and terbium are clearly lower than those of other REEs, which results in uneven extraction of REEs in the waste and low total REE leaching efficiency. The key reason is that the trivalent cerium and terbium in the waste are oxidized into RE oxides during NaOH roasting, which are difficult to dissolve in acid solution. To solve this problem, an optimized process of controlling the oxygen concentration during NaOH roasting is proposed in this paper. The influences of the oxygen concentration, roasting temperature, roasting time, mass ratio of waste phosphor to NaOH, HCl solution concentration, acid leaching temperature, acid leaching time, and liquid–solid ratio on the REE leaching efficiency were investigated. Under the optimum conditions, the leaching efficiencies of cerium and terbium increased dramatically and the total REE leaching efficiency is 99.11%.

Leaching kinetics of copper and valuable metal extraction from copper-cadmium residues of zinc hydrometallurgy by oxidation acid leaching

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jihao Guo ◽  
Hongao Xu ◽  
Bo Li ◽  
Yonggang Wei ◽  
Hua Wang
Keyword(s):  
Hydrogen Peroxide ◽  
Acid Concentration ◽  
Acid Leaching ◽  
Metal Extraction ◽  
Agitation Rate ◽  
Leaching Kinetics ◽  
Solid Ratio ◽  
Zinc Hydrometallurgy ◽  
Kinetics Of ◽  
Leaching Efficiency

Abstract Multiple purification of zinc sulfate solution is an important process for zinc hydrometallurgy, and large quantities of copper-cadmium residues are generated as byproducts in this process. Copper-cadmium residues contain a large number of valuable metals that must be recovered. A comprehensive extraction process has been proposed using sulfuric acid as the leaching reagent and hydrogen peroxide as the oxidizing reagent. The effects of acid concentration, leaching temperature, leaching time, liquid-to-solid ratio, hydrogen peroxide dosage and stirring speed on the leaching efficiency were investigated. The optimum conditions were determined as an acid concentration of 150 g/L, liquid-to-solid ratio of 4:1, hydrogen peroxide amount of 20 mL, time of 60 min, temperature of 30 °C, particle size of −d75 μm, and agitation rate of 300 r/min. It was concluded that the leaching efficiency of copper and cadmium reached 97%, but because of the existence of zinc sulfide in the residues, a lower leaching efficiency of zinc was obtained. Furthermore, the leaching kinetics of copper was also studied based on the shrinking core model. The activation energy for copper leaching was 5.06 kJ/mol, and the leaching process was controlled by the diffusion through the product layer.

Study on photocatalytic degradation of methylene blue by TiO2 synthesiszed from titanium slag using a new decomposition agent

2021 ◽  
Vol 11 (1) ◽  
pp. 89-93
Author(s):  
Chinh Tran Van ◽  
Anh Tran Thi Hien ◽  
Tu Ha Thi Cam ◽  
Hoai Truong Viet ◽  
Phuong Nguyen Thi Hoai ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Degradation ◽  
Acid Leaching ◽  
Mass Ratio ◽  
Optimum Conditions ◽  
Titanium Slag

This paper describes a novel process for the synthesis of TiO2 from titanium slag, which is realized via roasting titanium slag with KHSO4, acid leaching and hydrolysis. The results showed that the optimum conditions were a mass ratio of KHSO4 to titanium slag of 6, a temperature of 600 oC for 1,5 hours. Besides, this study investigated the possibility of synthesized TiO2 for photocatalytic degradation of methylene blue.

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 Recovery of Silicon Dioxide from Waste Foundry Sand and Alkaline Activation of Desilicated Foundry Sand

2020 ◽  
Vol 6 (4) ◽  
pp. 700-714
Author(s):  
Tebogo Mashifana ◽  
Thandiwe Sithole
Keyword(s):  
Potassium Hydroxide ◽  
Solution Concentration ◽  
Curing Temperature ◽  
Strength Development ◽  
Waste Generation ◽  
Optimum Conditions ◽  
Foundry Sand ◽  
Solid Ratio ◽  
Waste Foundry Sand ◽  
Alkaline Activator

Abstract This study was conducted to recover silica (desilication) as a valuable metalloid from waste foundry sand (WFS) by a leaching process and to find application for desilicated foundry sand (DFS). The leaching time applied was 5 h; 3 M of potassium hydroxide (KOH) was used as a leaching reagent. The agitation speed of 200 rpm and the liquid/solid ratio of 25 were found to be the best conditions for optimum leaching results. A geopolymer from DFS was developed by using NaOH as an alkaline activator. The results obtained showed that the optimum conditions for the synthesis of a geopolymer were 15 M NaOH, 150 µm DFS particle size, and a curing temperature of 80 ℃ for 72 h. The geopolymer strength development was due to the formation of Phillipsite and Kalsilite as new hydration products. At the optimum alkaline solution concentration, the highest unconfined compressive strength (UCS) of 4.8 MPa was achieved. The developed geopolymer met the minimum strength requirements for load bearing material. This study provides an innovative and novel solution for the beneficiation of spent foundry sand and the recovery of a valuable metalloid, resulting to zero waste generation. Graphical Abstract

Study on Leaching Zinc Calcine with High Iron

2013 ◽  
Vol 826 ◽  
pp. 118-121
Author(s):  
Jin Lin Yang ◽  
Hong Mei Zhang ◽  
Xiu Juan Su ◽  
Shao Jian Ma
Keyword(s):  
Sulfuric Acid ◽  
Acid Concentration ◽  
Great Influence ◽  
Sulfuric Acid Concentration ◽  
Acid Leaching ◽  
Leaching Rate ◽  
Iron Extraction ◽  
High Iron ◽  
Solid Ratio ◽  
Leaching Efficiency

In recent years, recovering zinc from zinc calcine with high iron has been a matter of discussion. In this paper, sulfuric acid leaching was carried out to assess the effect of several parameters on zinc and iron extraction in zinc calcine with high iron in which the grade of zinc and iron is 53.90% and 19.38%, respectively. Parameters, such as stirring speed, sulfuric acid concentration, liquid to solid ratio and leaching time, were investigated. The results show that leaching time has done nothing to the leaching rate, but has great influence on leaching efficiency. Liquid to solid ratio and sulfuric acid concentration have significant influence on leaching results, and stirring rate has not obvious influence on leaching results. Under the condition of 120g/L sulfuric acid, 6:1 liquid to solid ratio, 55°C leaching temperature and 120min leaching time, the recovery of zinc and iron is 82.24% and 9.64%, respectively. It is obvious that ZnO in zinc calcine is easy to dissolve in acidity solution, which shown in two aspects: high leaching rate and high leaching speed. ZnO can be dissolved entirely in sufficient sulfuric acid in 10min.

Factors of Extracting Lithium from Lepidolite by Sulfate Roasting and Dilute Sulphuric Acid Leaching

2014 ◽  
Vol 522-524 ◽  
pp. 1467-1470 ◽  
Author(s):  
Xiang Zhong Kong ◽  
Hua Ye ◽  
Yu Qin
Keyword(s):  
Sulphuric Acid ◽  
Extraction Efficiency ◽  
Acid Leaching ◽  
Mass Ratio ◽  
Roasting Temperature ◽  
Roasting Time

Sulfate roasting and dilute sulphuric acid leaching were applied to extract lithium from lepidolite. Several conditions including roasting temperature, roasting time, K2SO4and CaO were investigated to improve the lithium extraction efficiency, the final lithium extraction efficiency could attain 94% with the conditions as follows: roasting temperature 850°C, roasting time 2 h, K2SO4to lepidolite mass ratio 0.15 and CaO to lepidolite mass ratio 0.75.

scholarly journals A New Process of Extracting Titanium from Vanadium–Titanium Magnetite

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 327
Author(s):  
Yandong Li ◽  
Shuangyin Chen ◽  
Huamei Duan
Keyword(s):  
Recovery Rate ◽  
Acid Leaching ◽  
Leaching Rate ◽  
Optimum Conditions ◽  
Solid Ratio ◽  
New Process ◽  
Leaching Experiments ◽  
Panxi Area ◽  
Vanadium Titanium ◽  
Titanium Magnetite

A new process of extracting titanium from vanadium–titanium magnetite (VTM) in the Panxi area in Sichuan, China is introduced in this work. Various experiments, including reduction–magnetic separation, leaching and hydrolyzing experiments, are carried out. The results show that the optimum conditions for leaching experiments are an acid/slag ratio of 4:1, a leaching temperature of 60 °C, a leaching time of 80 min, and a liquid/solid ratio of 3.2:1. The leaching rate of titanium in Ti-bearing slag is 92.41%. The optimum conditions for hydrolyzing experiments are an H+ concentration of 0.75 g·L−1, hydrolyzing temperature of 100 °C, and hydrolyzing time of 180 min, and the hydrolyzing rate of titanium in acid leaching liquor is 96.80%. After the leaching and hydrolyzing experiments, the recovery rate of titanium from the Ti-bearing slag is 89.45%.

A Novel Technology of Molybdenum Extraction from Ni-Mo Alloy

2014 ◽  
Vol 997 ◽  
pp. 512-516
Author(s):  
Qiong Song ◽  
Guang Sheng Huo ◽  
Can Cao
Keyword(s):  
Ion Exchange ◽  
Exchange Process ◽  
Leach Liquor ◽  
Acid Oxidation ◽  
Test Results ◽  
Mass Ratio ◽  
Optimum Conditions ◽  
Solid Ratio ◽  
Ion Exchange Process ◽  
Novel Technology

The recovery of molybdenum from Ni-Mo alloy was investigated by acid oxidation leaching in H2SO4-NaClO3 system and then ion exchange process of leach liquor. The results in the leaching tests show that the leaching rates of nickel, molybdenum and iron are 99%, 97% and 98% respectively under the optimum conditions of H2SO4 dosage of 0.24mol per 20g Ni-Mo alloy, mass ratio of NaClO3/Ni-Mo alloy of 1.0, liquid-solid ratio of 4:1, leaching temperature of 100oC and time of 4h. The extraction of molybdenum in leach liquor was studied by ion exchange. The test results of resins selection show that the D308 resin is the best among resins on molybdenum adsorption. The results from the column tests of the D308 resin indicate that the mass ratio of Ni/Mo in effluent reaches to 10.84 from initial ratio of 0.607 and the adsorption rate of molybdenum is 94.4%.

Extraction of Rare Earth Elements from Waste Trichromatic Fluorescent Phosphors

2013 ◽  
Vol 788 ◽  
pp. 279-282 ◽  
Author(s):  
Yu Feng Wu ◽  
Rui Qing Li ◽  
Qi Jun Zhang ◽  
Wei Wang
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Reaction Time ◽  
Rare Earth Elements ◽  
Spinel Structure ◽  
Weight Ratio ◽  
Acid Leaching ◽  
Red Phosphors ◽  
Alkali Fusion ◽  
Leaching Efficiency

Two methods, direct acid leaching, alkali fusion and acid leaching, were adopted to deal with the Waste Trichromatic Fluorescent Phosphors (WTFPs). The research results showed that using the direct acid leaching method can only dissolved the Red phosphors. And yet, high-temperature alkali fusion could effectively destroy the Mg-Al spinel structure of the components of the Blue and the Green phosphors, and make REEs dissolved completely. The acid leaching efficiency of REEs could reach 100% when the weight ratio of NaOH with WTFPs is 6:1, and the calcination temperature is 900 °C and the reaction time is 4 hrs.

Pressure Leaching of Limonitic Laterite Ores in H2SO4-Mg(NO3)2 Medium

2012 ◽  
Vol 524-527 ◽  
pp. 2021-2025
Author(s):  
Bao Zhong Ma ◽  
Cheng Yan Wang ◽  
Wei Jiao Yang ◽  
Fei Yin ◽  
Yong Qiang Chen
Keyword(s):  
Reaction Temperature ◽  
Pressure Leaching ◽  
Mass Ratio ◽  
Optimum Conditions ◽  
Solid Ratio ◽  
Nickel Cobalt ◽  
Laterite Ores ◽  
Acid Consumption ◽  
Leaching Experiments ◽  
Laterite Ore

A limonitic laterite ore from Indonesea was treated by pressure leaching in H2SO4-Mg(NO3)2 medium, using Mg(NO3)2 as an oxidant. Experiments were conducted in order to determine the optimum conditions by studying various parameters, including Mg(NO3)2/ore mass ratio, initial acidity, reaction temperature, holding time and liquid/solid ratio. Pressure leaching experiments showed that nickel, cobalt and iron extractions were 90.8 %, 91.9 % and 2.1 % after 60 min of leaching at 493 K with 0.06 g/g Mg(NO3)2/ore mass ratio, 140 g/L initial acidity and 2 mL/g liquid/solid ratio.The total decrement of acid consumption was 72 g H2SO4/kg ore in the presence of Mg(NO3)2.

Sign in / Sign up

Export Citation Format

Share Document