Reaction kinetics of malachite in ammonium carbamate solution

2015 ◽  
Vol 69 (9) ◽  
Author(s):  
Ying-Bo Mao ◽  
Jiu-Shuai Deng ◽  
Shu-Ming Wen ◽  
Jian-Jun Fang
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Dissolution Rate ◽  
Batch Reactor ◽  
Shrinking Core Model ◽  
Surface Chemical ◽  
Surface Chemical Reaction ◽  
Ammonium Carbamate ◽  
Shrinking Core ◽  
Kinetics Of

AbstractThe dissolution of malachite particles in ammonium carbamate (AC) solutions was investigated in a batch reactor, using the parameters of temperature, AC concentration, particle size, and stirring speed. The shrinking core model was evaluated for the dissolution rate increased by decreasing particle size and increasing the temperature and AC concentration. No important effect was observed for variations in stirring speed. Dissolution curves were evaluated in order to test shrinking core models for fluid-solid systems. The dissolution rate was determined as being controlled by surface chemical reaction. The activation energy of the leaching process was determined as 46.04 kJ mol

Kinetics of Atmospheric Acid Leaching of a Limonitic Laterite

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.

Leaching Kinetics and Seperation of Antimony and Arsenic from Arsenic Alkali Residue

2011 ◽  
Vol 402 ◽  
pp. 57-60 ◽  
Author(s):  
Gui Sheng Zeng ◽  
Hui Li ◽  
Su Hua Chen ◽  
Xin Man Tu ◽  
Wen Bin Wang
Keyword(s):  
Shrinking Core Model ◽  
Leaching Kinetics ◽  
Surface Chemical ◽  
Leaching Rate ◽  
Kinetics Equation ◽  
Surface Chemical Reaction ◽  
Liquid Ratio ◽  
Shrinking Core ◽  
Solid Liquid ◽  
Kinetics Of

The separation of antimony and arsenic and leaching kinetics of arsenic from arsenic alkali residue were investigated. The influencing factors such as solid/liquid ratio, stir speed, temperature and time on leaching of arsenic were studied. The results show that the leaching rate reaches 87.75% at the condition of solid/liquid ratio of 1:4 , stir speed of 600r/min ,temperature of 90°C and time of 60min. The leaching process was controlled by the surface chemical reaction and the kinetics of leaching arsenic followed the model of shrinking core. The activation energy was found to be 666.57kJ/mol. The kinetics equation was expressed as shrinking core model.

scholarly journals Fluoride Leaching of Titanium from Ti-Bearing Electric Furnace Slag in [NH4+]-[F−] Solution

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1176
Author(s):  
Fuqiang Zheng ◽  
Yufeng Guo ◽  
Feng Chen ◽  
Shuai Wang ◽  
Jinlai Zhang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Electric Furnace ◽  
Kinetic Equations ◽  
Surface Chemical ◽  
Leaching Rate ◽  
Surface Chemical Reaction ◽  
Mechanism And Kinetics ◽  
Semi Empirical ◽  
Kinetics Of ◽  
Furnace Slag

The effects of F− concentration, leaching temperature, and time on the Ti leaching from Ti-bearing electric furnace slag (TEFS) by [NH4+]-[F−] solution leaching process was investigated to reveal the leaching mechanism and kinetics of titanium. The results indicated that the Ti leaching rate obviously increased with the increase of leaching temperature and F− concentration. The kinetic equation of Ti leaching was obtained, and the activation energy was 52.30 kJ/mol. The fitting results of kinetic equations and calculated values of activation energy both indicated that the leaching rate of TEFS was controlled by surface chemical reaction. The semi-empirical kinetics equation was consistent with the real experimental results, with a correlation coefficient (R2) of 0.996. The Ti leaching rate reached 92.83% after leaching at 90 °C for 20 min with F− concentration of 14 mol/L and [NH4+]/[F−] ratio of 0.4. The leaching rates of Si, Fe, V, Mn, and Cr were 94.03%, 7.24%, 5.36%, 4.54%, and 1.73%, respectively. The Ca, Mg, and Al elements were converted to (NH4)3AlF6 and CaMg2Al2F12 in the residue, which can transform into stable oxides and fluorides after pyro-hydrolyzing and calcinating.

scholarly journals Macerals of Shengli Lignite in Inner Mongolia of China and Their Combustion Reactivity

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Ying Yue Teng ◽  
Yu Zhe Liu ◽  
Quan Sheng Liu ◽  
Chang Qing Li
Keyword(s):  
Activation Energy ◽  
Homogeneous Model ◽  
Optical Microscope ◽  
Core Model ◽  
Shrinking Core Model ◽  
Compact Structure ◽  
Shrinking Core ◽  
Combustion Reactivity ◽  
Combustion Processes ◽  
Kinetics Of

The macerals, including fusinitic coal containing 72.20% inertinite and xyloid coal containing 91.43% huminite, were separated from Shengli lignite using an optical microscope, and their combustion reactivity was examined by thermogravimetric analysis. Several combustion parameters, including ignition and burnout indices, were analyzed, and the combustion kinetics of the samples were calculated by regression. Fusinitic coal presented a porous structure, while xyloid coal presented a compact structure. The specific surface area of fusinitic coal was 2.5 times larger than that of xyloid coal, and the light-off temperature of the former was higher than that of the latter. However, the overall combustion reactivity of fusinitic coal was better than that of xyloid coal. The combustion processes of fusinitic and xyloid coals can be accurately described by both the homogeneous model and the shrinking core model. The features of xyloid coal agree with the shrinking core model when its conversion rate is 10%–90%. The activation energy of fusinitic coal during combustion can be divided into three phases, with the middle phase featuring the highest energy. The activation energy of xyloid coal is lower than that of fusinitic coal in the light-off phase, which may explain the low light-off temperature of this coal.

Experimental Investigation of the SO2 Abatement Capacity of South African Calcium-Based Materials

2007 ◽  
Author(s):  
Zachary O. Siagi ◽  
Makame Mbarawa
Keyword(s):  
Particle Size ◽  
Dissolution Rate ◽  
South African ◽  
Efficient Operation ◽  
Shrinking Core ◽  
Caco3 Particle ◽  
Ph Stat ◽  
Kinetics Of ◽  
Different Sources ◽  
So2 Absorption

One of the most important steps in the wet limestone-gypsum flue gas desulphurization (WFGD) process is CaCO3 dissolution, which provides the dissolved alkalinity necessary for SO2 absorption. Accurately evaluating the CaCO3 dissolution rate is important in the design and efficient operation of WFGD plants. In the present work, the dissolution of limestone from different sources in South Africa has been studied in a pH-stat apparatus under conditions similar to those encountered in wet FGD processes. The influence of various parameters such as the reaction temperature (30 ≤ T ≤ 70°C), CaCO3 particle size (25 ≤ dp ≤ 63μm), solution acidity (4 ≤ pH ≤ 6), and chemical composition were studied in order to determine the kinetics of CaCO3 dissolution. The results obtained indicate that the dissolution rate increased with a decrease in particle size and an increase in temperature. The dissolution curves were evaluated in order to test the shrinking core model for fluid–solid systems. The analysis indicated that the dissolution of CaCO3 was controlled by chemical reaction, i.e. 1 − (1 − X)1/3 = kt.

The Effect of Temperature on the Leaching of Malachite in Phosphoric Acid Solution

2014 ◽  
Vol 962-965 ◽  
pp. 818-821 ◽  
Author(s):  
Cui Cui Ji ◽  
Dan Dan Wu ◽  
Shu Ming Wen ◽  
Jiu Shuai Deng
Keyword(s):  
Phosphoric Acid ◽  
Acid Solution ◽  
Phosphoric Acid Solution ◽  
Effect Of Temperature ◽  
Solution Temperature ◽  
Shrinking Core Model ◽  
Surface Chemical ◽  
Leaching Rate ◽  
Surface Chemical Reaction ◽  
Shrinking Core

In this study, the effect of leaching of malachite was investigated using phosphoric acid solution as leaching agent. The effect of temperature on the leaching of malachite was investigated. The leaching rate increased with increasing solution temperature, and a kinetic model was developed to represent this relationship. The leaching was controlled by the shrinking core model for surface chemical reaction. The activation energy of the leaching process was determined to be 30.65kJ/mol.

Mechanisms and Kinetics of Silica-Rich Binary Na2O-SiO2 Glass Corrosion in 100°C Water at pH=7

2007 ◽  
Vol 336-338 ◽  
pp. 1823-1826 ◽  
Author(s):  
K.G. Nickel ◽  
S. Merkel
Keyword(s):  
Dissolution Rate ◽  
Rate Constant ◽  
Edge Length ◽  
Sio2 Content ◽  
Shrinking Core Model ◽  
Water Interaction ◽  
Glass Corrosion ◽  
Shrinking Core ◽  
Dissolution Rate Constant ◽  
Kinetics Of

Sodium-rich glasses of the system Na2O-SiO2 are well known to be easily soluble in water. This is not true for silica-rich compositions. We have manufactured quenched glasses with silica contents between 65 and 80 wt.% SiO2 and followed the water interaction at 100°C by measuring mass and sample dimensions in intervals. Comparing the path of edge length, mass and volume to a general shrinking core model for cuboids we conclude that only compositions between 65 and 70 wt% SiO2 can be described well by a simple dissolution process. The logarithm of the dissolution rate constant varies linearly with the SiO2 content. At higher silica contents the mechanism changes towards leaching of sodium. We propose changing glass structures to be responsible for the change in mechanism.

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

Metals ◽  
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.

Dissolution kinetics of cerussite in an alternative leaching reagent for lead

2015 ◽  
Vol 69 (3) ◽  
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

scholarly journals Study on indium leaching from mechanically activated hard zinc residue

2011 ◽  
Vol 47 (1) ◽  
pp. 63-72 ◽  
Author(s):  
J.H. Yao ◽  
X.H. Li ◽  
Y.W. Li
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Planetary Mill ◽  
Leaching Rate ◽  
Obvious Effect ◽  
Diffusion Controlled ◽  
Leaching Reaction ◽  
Kinetics Of ◽  
Positive Effect ◽  
Solution Kinetics

In this study, changes in physicochemical properties and leachability of indium from mechanically activated hard zinc residue by planetary mill were investigated. The results showed that mechanical activation increased specific surface area, reaction activity of hard zinc residue, and decreased its particle size, which had a positive effect on indium extraction from hard zinc residue in hydrochloric acid solution. Kinetics of indium leaching from unmilled and activated hard zinc residue were also investigated, respectively. It was found that temperature had an obvious effect on indium leaching rate. Two different kinetic models corresponding to reactions which are diffusion controlled, [1-(1- x)1/3]2=kt and (1-2x/3)-(1-x)2/3=kt were used to describe the kinetics of indium leaching from unmilled sample and activated sample, respectively. Their activation energies were determined to be 17.89 kJ/mol (umilled) and 11.65 kJ/mol (activated) within the temperature range of 30?C to 90?C, which is characteristic for a diffusion controlled process. The values of activation energy demonstrated that the leaching reaction of indium became less sensitive to temperature after hard zinc residue mechanically activated by planetary mill.

Sign in / Sign up

Export Citation Format

Share Document