Comprehensive Extraction of Silica and Alumina from High-Alumina Coal Gangue (HACG): Hematite Involved Roasting − Alkaline Leaching − Bayer Digestion Process

Author(s):  
Hongyang Wang ◽  
Xiaoxue Zhang ◽  
Cheng Liu ◽  
Leiting Shen
2020 ◽  
Vol 7 (4) ◽  
pp. 192132 ◽  
Author(s):  
Quancheng Yang ◽  
Fan Zhang ◽  
Xingjian Deng ◽  
Hongchen Guo ◽  
Chao Zhang ◽  
...  

Vast quantities of gangue from coal mining and processing have accumulated over the years and caused significant economic and environmental problems in China. For high added-value utilization of alumina rich coal gangue (ARCG), a mild hydro-chemical process was investigated to extract alumina. The influences of NaOH concentration, mass ratio of alkali to gangue, reaction temperature and reaction time were systematically studied. An alumina extraction rate of 94.68% was achieved at the condition of NaOH concentration 47.5%, alkali to gangue ratio of 6, reaction temperature of 260°C and reaction time of 120 min. The obtained leaching residues were characterized through X-ray diffraction, scanning electron microscopy and energy-dispersive spectrometer. Research confirmed that kaolinite the main alumina-bearing phase of ARCG can be decomposed and transformed to Na 8 Al 6 Si 6 O 24 (OH) 2 (H 2 O) 2 and Ca 2 Al 2 SiO 6 (OH) 2 at relatively low temperature and short reaction time. Additionally, Na 8 Al 6 Si 6 O 24 (OH) 2 (H 2 O) 2 and Ca 2 Al 2 SiO 6 (OH) 2 are unstable and will transform to alumina-free phase NaCaHSiO 4 under the optimal conditions, which is the major reason for high alumina extraction rates.


2013 ◽  
Vol 652-654 ◽  
pp. 1527-1532 ◽  
Author(s):  
Guan Li Xu ◽  
Chuan Min Sun ◽  
Yao Sun ◽  
Hai Liao

Coal gangue is a kind of solid waste which is discharged from coal mining and coal washing. Dumped gangues do not only take a large land occupation but also pollute air and water. Treatment and utilizing of coal gangues has become the major issue for the coal industry to resolve. As major experimental material in this study, the coal gangue from Dawukou, Shizuishan, Ningxia province, China had been analyzed to have high-alumina content, and it could been used as alumina constituent for the preparation of sulphoaluminate cement. In this paper, alite-sulphoaluminate cements were prepared at 1330°C using coal gangue, limestone and gypsum as major main materials, fluorite and barite as minor materials. The result shows that major clinker minerals of the cement are sulphoaluminate, alite and belite, while major hydrate is ettringite, compressive strength of the cement is 48.9MPa after 7d. These experiments provide a new method of coal gangue comprehensive utilization.


2012 ◽  
Vol 198-199 ◽  
pp. 9-13
Author(s):  
Hai Li Cheng ◽  
Fei Hua Yang ◽  
Jie Zhang ◽  
Yi Wang

In this paper, the Neimenggu high alumina coal gangue was calcined at 400°C~1000°C, its micro-structure in different calcining temperature was studied using XRD and IR, and then the preferred activated condition and the PAI were investigated by testing the strength of cement mortars with activated coal gangue. The result shows that: the optimal calcining temperature of the gangue is 800°C, at this temperature the high activated SiO2 and AI2O3 can be decomposed from the gangue. The activity of the original gangue is very high, the PAI of the cement mortars with 800°C activated coal gangue can achieve to 126%, and thus can be used as high activity cement admixture. The PAI of the high alumina gangue is higher than that of coal gangue from other parts of China.


Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 57 ◽  
Author(s):  
Siwei Li ◽  
Jian Pan ◽  
Deqing Zhu ◽  
Zhengqi Guo ◽  
Yue Shi ◽  
...  

In this study, a novel process was established for extraction of Fe and Al from a complex high aluminum iron ore (33.43% Fetotal and 19.09% Al2O3). The main steps in the proposed process included pre-reducing high alumina iron ore and subsequent smelting to produce pig iron and rich-alumina slag, followed by alkaline leaching of the slag to obtain sodium aluminate solution and a clean slag. When smelting the pre-reduced high alumina iron ore pellets at 1625 °C for 30 min with a slag basicity of 0.40, the pig iron yielded 97.08% Fe and extracted 0.13% Al2O3, together with an iron recovery of 94.54%. In addition, more than 68.93% Al2O3 was recovered by leaching the slag, which was achieved by firstly roasted the slag at 900 °C for 2 h and then alkaline leaching at 95 °C for 2 h with a liquid-to-solid ratio of 10 mL/g. In addition, the alkaline leaching slag could potentially be used as raw material for construction purpose, which mainly consisted of SiO2 and CaO.


2015 ◽  
Vol 2 (3) ◽  
pp. 26-31
Author(s):  
K. Węglarzy ◽  
Yu. Shliva ◽  
B. Matros ◽  
G. Sych

Aim. To optimize the methane digestion process while using different recipes of substrate components of ag- ricultural origin. Methods. The chemical composition of separate components of the substrate of agricultural by-products, industrial wastes, fats of the agrorefi nery and corn silage was studied. Dry (organic) mass, crude protein (fat) fi ber, loose ash, nitrogen-free exhaust were estimated in the components and the productivity of biogas was determined along with the methane content. These data were used as a basis for daily recipes of the substrate and the analysis of biogas production at the biogas station in Kostkowice. Results. The application of by-products of agricultural production solves the problem of their storage on boards and in open containers, which reduces investment costs, related to the installation of units for their storage. Conclusions. The return on investment for obtaining electric energy out of agricultural biogas depends considerably on the kind of the substrate used and on technological and market conditions.


2018 ◽  
Author(s):  
Hattie Ring ◽  
Zhe Gao ◽  
Nathan D. Klein ◽  
Michael Garwood ◽  
John C. Bischof ◽  
...  

The Ferrozinen assay is applied as an accurate and rapid method to quantify the iron content of iron oxide nanoparticles (IONPs) and can be used in biological matrices. The addition of ascorbic aqcid accelerates the digestion process and can penetrate an IONP core within a mesoporous and solid silica shell. This new digestion protocol avoids the need for hydrofluoric acid to digest the surrounding silica shell and provides and accessible alternative to inductively coupled plasma methods. With the updated digestion protocol, the quantitative range of the Ferrozine assay is 1 - 14 ppm. <br>


2018 ◽  
Author(s):  
Hattie Ring ◽  
Zhe Gao ◽  
Nathan D. Klein ◽  
Michael Garwood ◽  
John C. Bischof ◽  
...  

The Ferrozinen assay is applied as an accurate and rapid method to quantify the iron content of iron oxide nanoparticles (IONPs) and can be used in biological matrices. The addition of ascorbic aqcid accelerates the digestion process and can penetrate an IONP core within a mesoporous and solid silica shell. This new digestion protocol avoids the need for hydrofluoric acid to digest the surrounding silica shell and provides and accessible alternative to inductively coupled plasma methods. With the updated digestion protocol, the quantitative range of the Ferrozine assay is 1 - 14 ppm. <br>


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