scholarly journals Mechanism and Modelling of Reactive Crystallization Process of Lithium Carbonate

Processes ◽  
2019 ◽  
Vol 7 (5) ◽  
pp. 248 ◽  
Author(s):  
Shaolei Zhao ◽  
Jie Gao ◽  
Siyang Ma ◽  
Chao Li ◽  
Yiming Ma ◽  
...  

The reactive crystallization of lithium carbonate (Li2CO3) from lithium sulfate (Li2SO4) and sodium carbonate (Na2CO3) solutions is a key process in harvesting solid lithium, whether from ores, brines, or clays. However, the process kinetics and mechanism remain poorly understood and the modelling of the reactive crystallization of Li2CO3 is not available. Hence, this work aims to determine the kinetics and mechanisms of the nucleation and growth of Li2CO3 reactive crystallization by induction time measurements and to model and optimize the crystallization process using response surface methodology. Induction time measurements were carried out as functions of initial supersaturation and temperature using a laser method. It was found that the primary nucleation mechanism of Li2CO3 varies with solution supersaturations, in which, expectedly, the heterogenous nucleation mechanism dominates at low supersaturations while the homogeneous nucleation mode governs at high supersaturations. The transition point between heterogenous and homogenous nucleation was found to vary with temperatures. Growth modes of Li2CO3 crystals were investigated by relating induction time data with various growth mechanisms, revealing a two-dimensional nucleation-mediated growth mechanism. The modelling and optimization of a complex reactive crystallization were performed by response surface methodology (RSM), and the effects of various crystallization parameters on product and process performances were examined. Solution concentration was found to be the critical factor determining the yield of crystallization, while stirring speed was found to play a dominant role in the particle size of Li2CO3 crystals. Our findings may provide a better understanding of the reactive crystallization process of Li2CO3 and are critical in relation to the crystallization design and control of Li2CO3 production from lithium sulfate sources.

2015 ◽  
Vol 26 (6) ◽  
pp. 730-736
Author(s):  
Se-Eun Lee ◽  
Jae-Kyeong Kim ◽  
Sang-Keun Han ◽  
Joo-Seung Chae ◽  
Keun-Duk Lee ◽  
...  

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Mohsen Keramati ◽  
Ismaeil Ghasemi ◽  
Mohammad Karrabi ◽  
Hamed Azizi

AbstractMicrocellular foam is a new class of material with superior properties due to smaller cell size and higher cell density compared to ordinary foams. In this work, microcellular foam of PP/EPDM/Organoclay with supercritical nitrogen as physical blowing agent was prepared via batch process. Experimental design was carried out according to Box-Behnken method and the effects of saturation pressure and foaming times as well as organoclay content on nucleation and final foam morphology were studied using response surface methodology (RSM). Three levels of saturation pressure, nanoclay content, and foaming time were chosen. The mathematical model and response surface graphs have been used to illustrate the relationship between considered parameters and foam properties. The results revealed that cell density and average cell diameter were affected by nanoclay content and pressure. Cell density was in the range of 109-1010 cell/cm3. Larger average cell sizes were observed as a result of increasing foaming time. Classic nucleation theory was used to study the nucleation mechanism. Nanoparticles acted as nucleating agents and changed nucleation mechanism from homogenous to heterogeneous by decreasing nucleating free energy. In order to find out nucleating energy reduction, gas-polymer-nanoparticle contact angle (Ө), was calculated by measuring surface and interfacial free energies of neat polymers and nanoparticle. In addition, nucleation efficiency of organoclay was estimated and the results showed that despite low nucleating efficiency, nucleation is dominated by presence of nanoclay.


2021 ◽  
Vol 39 (1) ◽  
pp. 98-104
Author(s):  
Dongmei Zhu ◽  
Qianwen Chen ◽  
Tingsheng Qiu ◽  
Guanfei Zhao ◽  
Xihui Fang

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