Leaching Kinetics of Rare Earth Elements in Phosphoric Acid from Phosphate Rock

Phosphate rock has been considered as one of the most significant secondary rare-earth resource, and the utilization of rare earth elements (REEs) in phosphate rock has attracted increasing attention. In this study, the leaching kinetics of REEs from a phosphate ore from China was studied with the variation of temperature and phosphoric acid concentration under the conditions: ratio of liquid to solid of 12 mL/g, stirring speed of 120 r/min, and phosphate particle size of −0.074 mm amounts 61.1%. The results suggest that there were two distinct stages in leaching process and kinetics of both stages followed shrinking core model. At fast reaction stage, the semi-empirical equation describing the kinetics was 1 − 3(1 − α)2/3 + 2(1 − α) = 1.885CH3PO40.89exp(−11220/8.31T)t. The semi-empirical equation for slow reaction stage was 1 − 3(1 − α)2/3 + 2(1 − α) = 0.299CH3PO42.50exp(−18720/8.31T)t. Using shrinking core model and time-to-a-given-fraction method, we found that leaching rate of fast reaction stage was controlled by solid product layer diffusion, and both solid product layer diffusion and chemical reaction determined slow reaction stage.

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Leaching Kinetics of Sulfides from Refractory Gold Concentrates by Nitric Acid

Metals ◽

10.3390/met9040465 ◽

2019 ◽

Vol 9 (4) ◽

pp. 465 ◽

Cited By ~ 8

Author(s):

Denis A. Rogozhnikov ◽

Andrei A. Shoppert ◽

Oleg A. Dizer ◽

Kirill A. Karimov ◽

Rostislav E. Rusalev

Keyword(s):

Mineral Resources ◽

Product Layer ◽

Yenisei Ridge ◽

Effect Of Temperature ◽

Leaching Kinetics ◽

Iron Recovery ◽

Refractory Gold ◽

Shrinking Core ◽

Semi Empirical ◽

Kinetics Of

The processing of refractory gold-containing concentrates by hydrometallurgical methods is becoming increasingly important due to the depletion of rich and easily extracted mineral resources, as well as due to the need to reduce harmful emissions from metallurgy, especially given the high content of arsenic in the ores. This paper describes the investigation of the kinetics of HNO3 leaching of sulfide gold-containing concentrates of the Yenisei ridge (Yakutia, Russia). The effect of temperature (70–85 °C), the initial concentration of HNO3 (10–40%) and the content of sulfur in the concentrate (8.22–22.44%) on the iron recovery into the solution was studied. It has been shown that increasing the content of S in the concentrate from 8.22 to 22.44% leads to an average of 45% increase in the iron recovery across the entire range temperatures and concentrations of HNO3 per one hour of leaching. The leaching kinetics of the studied types of concentrates correlates well with the new shrinking core model, which indicates that the reaction is regulated by interfacial diffusion and diffusion through the product layer. Elemental S is found on the surface of the solid leach residue, as confirmed by XRD and SEM/EDS analysis. The apparent activation energy is 60.276 kJ/mol. The semi-empirical expression describing the reaction rate under the studied conditions can be written as follows: 1/3ln(1 − X) + [(1 − X)−1/3 − 1] = 87.811(HNO3)0.837(S)2.948e−60276/RT·t.

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Application of the Shrinking-Core Models for Determination of Dissolution Kinetics of Mn and Zn from Spent Zinc–Carbon Battery Powder in Organic Acid Solution

Acta Chemica Iasi ◽

10.2478/achi-2019-0008 ◽

2019 ◽

Vol 27 (1) ◽

pp. 99-109 ◽

Cited By ~ 1

Author(s):

Tevfik Agacayak ◽

Hasan Ali Taner

Keyword(s):

Acetic Acid ◽

Acid Solution ◽

Acetic Acid Solution ◽

Dissolution Kinetics ◽

Kinetic Studies ◽

Product Layer ◽

Different Temperatures ◽

Shrinking Core ◽

Kinetics Of Dissolution ◽

Kinetics Of

Abstract In this study, dissolution kinetics of manganese and zinc from spent zinc–carbon batteries in acetic acid solution was investigated. To determine the kinetics of dissolution of manganese and zinc, shrinking core model was applied to dissolution recoveries obtained at different temperatures. As a result of kinetic studies, it was determined that manganese and zinc were dissolved in acetic acid solution by diffusion from product layer and then activation energies (Ea) were calculated.

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Kinetics of limestone decomposition in hot metal

Metallurgical Research & Technology ◽

10.1051/metal/2018055 ◽

2018 ◽

Vol 115 (6) ◽

pp. 611 ◽

Cited By ~ 1

Author(s):

Biao Tang ◽

Qifu Xiang ◽

Jing Wang ◽

Yunlong Zhang ◽

Xingyi Li ◽

...

Keyword(s):

Mass Transfer ◽

Heat Conduction ◽

Cross Section ◽

Gas Flow ◽

Kinetic Equations ◽

Product Layer ◽

Hot Metal ◽

Shrinking Core ◽

Kinetics Of ◽

Limestone Calcination

Compared with the traditional limestone calcination, this paper focuses on the conditions and temperature in hot metal where limestone calcines in converter steelmaking process. Considering heat transfer, mass transfer driven by concentration gradient and mass transfer (CO2 gas flow) driven by pressure gradient, macro kinetic models are established to describe limestone decomposition rate respectively. The method of rotating cylinder sample is used in the experiment of limestone decomposition in hot metal. The image processing software Image-Pro Plus is used to analyze the cross section of limestone calcined to get the unreacted core radius of cross section of cylindrical limestone. The results show that the decomposition mechanism of limestone follows the unreacted shrinking core model, the heat conduction of lime layer is the controlling step, the heat conduction and CO2 migration through the product layer determine the rate of limestone decomposition, and the corresponding kinetic equations are established.

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The Contrast Study of Microwave Heating and Traditional Heating Leaching Vanadium from Stone Coal with Sulfuric Acid Solution

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.774-776.660 ◽

2013 ◽

Vol 774-776 ◽

pp. 660-663

Author(s):

Hong Zhou Ma ◽

Yao Ning Wang ◽

Xin Zhe Lan

Keyword(s):

Sulfuric Acid ◽

Acid Solution ◽

Microwave Heating ◽

Sulfuric Acid Solution ◽

Product Layer ◽

Contrast Study ◽

Leaching Rate ◽

Solid Product ◽

Stone Coal ◽

Kinetics Of

The aim of this paper is to contrast the effect of the microwave heating and traditional heating leaching vanadium from stone coal with sulfuric acid solution, contrast the leaching rate of vanadium, kinetics of leaching vanadium and the phase change s of slag. The experiment results show that the leaching rate and leaching velocity of vanadium with microwave heating was higher greatly than traditional heating, the kinetics of leaching vanadium with two heating methods was similar and accords with unreacted core contraction model with have solid product layer model, the illite in the stone coal was decomposed with microwave heating, but the traditional heating could not decomposed.

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Kinetics of Atmospheric Acid Leaching of a Limonitic Laterite

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.319.14 ◽

2013 ◽

Vol 319 ◽

pp. 14-18

Author(s):

Kui Liu ◽

Xi Liu

Keyword(s):

Atmospheric Pressure ◽

Acid Leaching ◽

Shrinking Core Model ◽

Surface Chemical ◽

Surface Chemical Reaction ◽

Nickel Laterite ◽

Shrinking Core ◽

Semi Empirical ◽

Kinetics Of ◽

Rate Controlling Step

A limonitic nickel laterite was leached by sulfuric acid at atmospheric pressure. Kinetics of leaching within the temperature range of 75-100°C was studied. The leaching kinetics followed the shrinking core model. The diffusion through the liquid film could be negligible under the agitation speed of 600rpm or above. Surface chemical reaction was the rate-controlling step. The semi-empirical kinetic equation was determined and the activation energy was 52.843kJ/mol.

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Kinetics of iron removal from quartz under ultrasound-assisted leaching

High Temperature Materials and Processes ◽

10.1515/htmp-2020-0081 ◽

2020 ◽

Vol 39 (1) ◽

pp. 395-404

Author(s):

Chang-Qiao Yang ◽

Su-Qin Li

Keyword(s):

Removal Rate ◽

Input Power ◽

Product Layer ◽

Iron Removal ◽

Ultrasonic Power ◽

Leaching Process ◽

Rate Determining Step ◽

Shrinking Core ◽

Ultrasound Assisted ◽

Kinetics Of

AbstractKinetics of iron removal from quartz under the ultrasound-assisted leaching was explored in this paper, and the effects of temperature, leaching time, stirring speed and ultrasonic input power on iron removal were studied. The results revealed that the reaction kinetics followed the shrinking core model and the product layer internal diffusion was the rate-determining step in the ultrasound-assisted leaching process. The activation energy of the ultrasonic-assisted leaching reaction was 27.72 kJ/mol, which was 7.28 kJ/mol higher than that of the regular method. Moreover, the kinetic equation and mathematical model of iron removal from quartz were established. Compared with the regular leaching, only 40 min were required for the ultrasound-assisted leaching process to achieve an iron removal rate of up to 74%. Under the optimal parameters, SiO2 content of concentrate increased from 99.5828% to 99.9047%, and Fe2O3 content reduced from 0.0857% to 0.0223%. Additionally, it was found that the iron removal rate increased with increasing temperature, stirring speed or ultrasonic power.

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Properties and Kinetics of Selective Zinc Leaching with Choline Chloride and Urea

Minerals ◽

10.3390/min11080857 ◽

2021 ◽

Vol 11 (8) ◽

pp. 857

Author(s):

Jinxia Zhang ◽

Jiajing Dong ◽

Fusheng Niu ◽

Chao Yang

Keyword(s):

Choline Chloride ◽

Deep Eutectic Solvent ◽

Zinc Content ◽

Product Layer ◽

Layer Formation ◽

Solid Product ◽

Solid Ratio ◽

Secondary Recovery ◽

Kinetics Of ◽

Leaching Efficiency

A choline chloride-urea (ChCl-urea) deep eutectic solvent (DES) was used to experimentally investigate the secondary recovery of zinc from zinc-bearing dust sludge via a leaching process. The effects of varying the liquid–solid ratio, leaching temperature, stirring speed, and leaching time on the zinc leaching efficiency were determined, and the optimum values of these parameters were found to be 15:1, 90 °C, 400 rpm, and 600 min, respectively, at which a leaching efficiency of 86.87% was achieved. XRF and EDS analyses confirmed that the zinc content in the sludge decreased noticeably after leaching, while those of other elements did not, indicating the selective and efficient leaching of zinc. A study of the leaching kinetics showed that the reaction conforms to the nuclear shrinkage model without solid product layer formation, and the calculated apparent activation energy is 22.16 kJ/mol.

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Effect of Preliminary Alkali Desilication on Ammonia Pressure Leaching of Low-Grade Copper–Silver Concentrate

Metals ◽

10.3390/met10060812 ◽

2020 ◽

Vol 10 (6) ◽

pp. 812

Author(s):

Kirill Karimov ◽

Andrei Shoppert ◽

Denis Rogozhnikov ◽

Evgeniy Kuzas ◽

Semen Zakhar’yan ◽

...

Keyword(s):

Activation Energy ◽

Product Layer ◽

Core Model ◽

Pressure Leaching ◽

Low Grade ◽

Shrinking Core Model ◽

Spectroscopy Analysis ◽

Shrinking Core ◽

Ammonia Leaching ◽

Kinetics Of

Ammonia leaching is a promising method for processing low-grade copper ores, especially those containing large amounts of oxidized copper. In this paper, we study the effect of Si-containing minerals on the kinetics of Cu and Ag leaching from low-grade copper concentrates. The results of experiments on the pressure leaching of the initial copper concentrate in an ammonium/ammonium-carbonate solution with oxygen as an oxidizing agent are in good agreement with the shrinking core model in the intra-diffusion mode: in this case, the activation energies were 53.50 kJ/mol for Cu and 90.35 kJ/mol for Ag. Energy-dispersive X-ray spectroscopy analysis (EDX) analysis showed that reagent diffusion to Cu-bearing minerals can be limited by aluminosilicate minerals of the gangue. The recovery rate for copper and silver increases significantly after a preliminary alkaline desilication of the concentrate, and the new shrinking core model is the most adequate, showing that the process is limited by diffusion through the product layer and interfacial diffusion. The activation energy of the process increases to 86.76 kJ/mol for Cu and 92.15 kJ/mol for Ag. Using the time-to-a-given-fraction method, it has been shown that a high activation energy is required in the later stages of the process, when the most resistant sulfide minerals of copper and silver apparently remain.

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Dissolution kinetics of cerussite in an alternative leaching reagent for lead

Chemical Papers ◽

10.1515/chempap-2015-0034 ◽

2015 ◽

Vol 69 (3) ◽

Cited By ~ 6

Author(s):

Qi-Cheng Feng ◽

Shu-Ming Wen ◽

Yi-Jie Wang ◽

Qin-Bo Cao ◽

Wen-Juan Zhao

Keyword(s):

Dissolution Kinetics ◽

Product Layer ◽

Surface Chemical ◽

Surface Chemical Reaction ◽

Mixed Control ◽

Shrinking Core ◽

Two Stages ◽

Kinetics Of ◽

And Diffusion ◽

Rate Controlling Step

AbstractThe dissolution kinetics of cerussite was investigated using methanesulphonic acid (MSA) as an alternative leaching reagent. The effects of particle size, stirring speed, acid concentration, and reaction temperature on the lead dissolution rate were determined. The dissolution process followed the kinetic law of the shrinking-core model, and a corresponding mixed control model was found suitable for representing the rate-controlling step. The mixed kinetic model comprised two stages: surface chemical reaction (283 K to 303 K) and diffusion through the product layer (303 K to 323 K). The activation energies of these sequential stages were 43.20 kJ mol

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