scholarly journals Grinding Behavior and Potential Beneficiation Options of Bauxite Ores

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 314
Author(s):  
Evangelos Petrakis ◽  
Georgios Bartzas ◽  
Konstantinos Komnitsas
Keyword(s):  
Magnetic Separation ◽  
Al2o3 Content ◽  
Reduction Roasting ◽  
Optimum Conditions ◽  
First Order ◽  
Breakage Rate ◽  
Bauxite Ore ◽  
Magnetic Product ◽  
Grinding Time ◽  
Product Fraction

This laboratory study investigates selective grinding and beneficiation options for a Greek bauxite ore. First, a series of batch grinding tests were carried out in order to investigate the grinding behavior of the ore and the effect of the material filling volume (fc) on the distribution of aluminium- and iron-containing phases. Then, the ground ore was subjected to magnetic separation either as received or after reduction roasting in order to further explore potential beneficiation options. The results showed that grinding of the ore exhibits non-first order behavior, while the breakage rate varies with grinding time. Additionally, Al2O3 tends to concentrate in the coarser than 0.300 mm product fraction, while fc 10% and 2 min of grinding time are considered optimum conditions for good distribution of Al2O3 and Fe2O3. When different product fractions were subjected to magnetic separation, it was seen that the non-magnetic product obtained from the 0.300–1.18 mm fraction was more rich in Al2O3. In this fraction, the Al2O3 content increased from 58 wt% in the feed to 67.9 wt%, whereas the Fe2O3 content decreased from 22.4 wt% in the feed to 13.5 wt%. When the ore was subjected to a two-step treatment, involving reduction roasting followed by magnetic separation, the Fe2O3 grade decreased from 20.8 to 5.1 wt%, but in this case the recovery was very low.

scholarly journals Influence of Na2CO3 and K2CO3 Addition on Iron Grain Growth during Carbothermic Reduction of Red Mud

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1313 ◽  
Author(s):  
Dmitry Zinoveev ◽  
Pavel Grudinsky ◽  
Andrey Zakunov ◽  
Artem Semenov ◽  
Maria Panova ◽  
...  
Keyword(s):  
Magnetic Separation ◽  
Grain Growth ◽  
Red Mud ◽  
Carbothermic Reduction ◽  
Reduction Roasting ◽  
Alumina Production ◽  
Iron Aluminum ◽  
Bauxite Ore ◽  
Hsc Chemistry ◽  
Sodium And Potassium

Red mud is a by-product of alumina production from bauxite ore by the Bayer method, which contains considerable amounts of valuable components such as iron, aluminum, titanium, and scandium. In this study, an approach was applied to extract iron, i.e., carbothermic reduction roasting of red mud with sodium and potassium carbonates followed by magnetic separation. The thermodynamic analysis of iron and iron-free components’ behavior during carbothermic reduction was carried out by HSC Chemistry 9.98 (Outotec, Pori, Finland) and FactSage 7.1 (Thermfact, Montreal, Canada; GTT-Technologies, Herzogenrath, Germany) software. The effects of the alkaline carbonates’ addition, as well as duration and temperature of roasting on the iron metallization degree, iron grains’ size, and magnetic separation process were investigated experimentally. The best conditions for the reduction roasting were found to be as follows: 22.01% of K2CO3 addition, 1250 °C, and 180 min of duration. As a generalization of the obtained data, the mechanism of alkaline carbonates’ influence on iron grain growth was proposed.

Screening and Desilication of a Silicate Bacteria

2011 ◽  
Vol 236-238 ◽  
pp. 253-257
Author(s):  
Xian Zhen Zhang ◽  
De Si Sun ◽  
Hai Lin
Keyword(s):  
Particle Size ◽  
Incubation Time ◽  
Ph Value ◽  
Solution Temperature ◽  
Optimum Conditions ◽  
Initial Ph ◽  
Silicate Bacteria ◽  
Bauxite Ore

The strain Jgj-1 was isolated from Gaoan bauxite ore. The relations of desilication of the strain Jgj-1 and the pH of solution, temperature, shaking speed, incubation time, particle size were investigated. The results shows the optimum conditions of bioleaching are as following: at 28°C, initial pH value is 7.2, particle size 0.056mm, 200rpm shaking speed, incubation 5-7 days.

Recovery of iron from zinc calcines by reduction roasting and magnetic separation

2012 ◽  
Vol 35 ◽  
pp. 57-60 ◽  
Author(s):  
Ning Peng ◽  
Bing Peng ◽  
Li-Yuan Chai ◽  
Mi Li ◽  
Ji-Ming Wang ◽  
...  
Keyword(s):  
Magnetic Separation ◽  
Reduction Roasting

scholarly journals Kinetic Study of Photocatalytic Degradation of Tolonium Chloride Under High Pressure Irradiation in Aquatic Buffer Systems

2011 ◽  
Vol 8 (s1) ◽  
pp. S19-S26 ◽  
Author(s):  
M. Montazerozohori ◽  
S. Nezami ◽  
S. Mojahedi
Keyword(s):  
High Pressure ◽  
Photocatalytic Degradation ◽  
Kinetic Study ◽  
Rate Constants ◽  
Order Kinetic ◽  
Optimum Conditions ◽  
First Order ◽  
Reactor Cell ◽  
Order Kinetic Model ◽  
Tolonium Chloride

Anatase titanium dioxide catalyzed photodegradation of tolonium chloride at various bufferic pH of 2, 7, 9 and 12 in aqueous solution is presented. The effect of some physicochemical parameters such as initial concentration of dye, catalyst amount and reaction time on photocatalytic degradation has been investigated in a photo-reactor cell containing high pressure mercury lamp to obtain the optimum conditions in each bufferic pH at constant temperature. A complete spectrophotometric kinetic study of tolonium chloride under high pressure irradiation at buffer media was performed. The photocatalytic degradation observed rate constants (kobs) were found to be 2.90×10-3, 3.30×10-3, 3.20×10-3and 5.20×10-3min-1for buffer pH of 2-12 respectively. It was found that a pseudo-first-order kinetic model based on Langmuir-Hinshelwood one is usable to photodegradation of this compound at all considered buffer pH. In addition to these, the Langmuir-Hinshelwood rate constants, krfor the titled compound at various pH are reported.

scholarly journals Optimization of Operating Parameters on Dry Grinding of Calcite in a Stirred Media Mill Using the Box-Behnken Design

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 251
Author(s):  
Diler Katircioglu-Bayel
Keyword(s):  
Mass Fraction ◽  
Filling Ratio ◽  
Operating Parameters ◽  
Stirrer Speed ◽  
Solid Mass ◽  
Optimum Conditions ◽  
Box Behnken Design ◽  
Dry Grinding ◽  
Grinding Time ◽  
Stirred Media Mill

The optimization of the operating parameters of a stirred media mill in the dry grinding of calcite was investigated. A three-level Box-Behnken design was used for the purpose of examining the impact of four independent factors, the stirrer speed (SS), grinding time (GT), media filling ratio (MFR), and solid mass fraction (SMF), on the product particle size (d50). For the purpose of establishing an empirical correlation between operating parameters and responses, a series of experiments were carried out. Variance analysis showed a reasonably good value for d50 (R2 = 0.965). According to the software solutions, the optimum conditions for minimizing the d50 size were found to be 573 rpm stirrer speed, 11.18 min grinding time, 63% media filling ratio, and 11.52% solid mass fraction, with 3.78 µm for the d50 size. To verify the improvement of grinding, verification tests were performed using the above-mentioned optimum conditions and the average d50 size and standard deviation were found to be 3.83 µm and 0.025, respectively. The average d50 value obtained was smaller than those obtained in the 27 tests. Furthermore, when the optimum result obtained from the experiments was compared with the result obtained using the software, a 22% energy saving was achieved. The impacts of grinding on the structural characteristics of calcite particles were characterized by XRD analysis. XRD measurements indicated that no change was observed in the peak areas of ground calcite specimens compared to the untreated calcite specimen.

Optimal Recovery of Iron Values from a Low Grade Iron Ore using Reduction Roasting and Magnetic Separation

2014 ◽  
Vol 49 (12) ◽  
pp. 1927-1936 ◽  
Author(s):  
S. S. Rath ◽  
H. Sahoo ◽  
N. Dhawan ◽  
D. S. Rao ◽  
B. Das ◽  
...  
Keyword(s):  
Magnetic Separation ◽  
Iron Ore ◽  
Optimal Recovery ◽  
Low Grade ◽  
Reduction Roasting

scholarly journals Comparative biosorption study of Hg (II) using raw and chemically activated almond shell

2017 ◽  
Vol 36 (1-2) ◽  
pp. 521-548 ◽  
Author(s):  
AA Taha ◽  
AHE Moustafa ◽  
HH Abdel-Rahman ◽  
MMA Abd El-Hameed
Keyword(s):  
Isotherm Models ◽  
Optimum Conditions ◽  
Almond Shell ◽  
Shell Surface ◽  
First Order ◽  
Biosorption Process ◽  
Equilibrium Data ◽  
Batch Biosorption ◽  
Best Fit ◽  
Langmuir And Freundlich Models

This work presents a comparison between the biosorption of Hg (II) by raw almond shell and activated almond shell. Almond shell based activated carbon has been obtained by physicochemical activation. Batch biosorption results confirmed that, activating condition has a strong influence on the final biosorption process. The biosorbent was characterized using scanning electron microscopy and Fourier transform infrared spectroscopy. To optimize the biosorption conditions pH, adsorbent dose, initial concentration, contact time, stirring speed, and temperature on Hg (II) removal were studied. The optimum conditions for maximum Hg (II) was achieved at 20 and 10 min for raw almond shell and activated almond shell, respectively. The equilibrium data were described well by Langmuir, Freundlich, Dubinin–Radushkevich isotherm models and appling a test of model fitness. Best fit of Langmuir and Freundlich models were found for experimental data, which reveal the homogenous surface of raw almond shell and the heterogeneity of activated almond shell surface. The kinetic data had been divided into either pseudo first order or second order on the basis of the best fit obtained from calculations, confirmed by a test of kinetic validity. An industrial application was examined to improve high biosorption capacity of raw and activated almond shells toward Hg (II).

Photocatalytic degradation of dye pollutants in the presence of acetone

2001 ◽  
Vol 44 (6) ◽  
pp. 173-180 ◽  
Author(s):  
S.-M. Tsui ◽  
W. Chu
Keyword(s):  
Quantum Yield ◽  
Critical Factor ◽  
Reactive Dye ◽  
Optimum Conditions ◽  
Decay Kinetics ◽  
Triplet Energy ◽  
First Order ◽  
Dye Pollutants ◽  
Initial Ph ◽  
Reactive Red 2

The photodegradation of textile azo dyes in aqueous solution containing acetone (ACE) photosensitizer was investigated at 253.7 nm. In this study, a typical azo reactive dye (C I Reactive Red 2 - RR2) is used as the probe compound. ACE is a powerful photosensitizer that possesses high triplet energy, and the presence of ACE significantly enhances the overall photodegradation reaction through simultaneous sensitization. In the UV/ACE system, at the optimum conditions, over 97% of RR2 can be successfully decomposed and decolored within 300 seconds of retention time. The photodegradation mechanisms of RR2 involve both photodechlorination and photoreduction, which follow pseudo first-order decay kinetics. The quantum yield of the photolysis system has been evaluated as a function of ACE concentration and the initial pH. RR2 contains the chlorotriazinyl group, which undergoes hydrolysis and results in the formation of hydrochloric acid, indicating that the photodechlorination process is the dominant reaction mechanism. The photo-product, H+, is likely to retard the quantum yield of dye decay, suggesting that the initial pH is a critical factor in changing the photodecolorization rates of dye. Generally, this system is more favorable at higher pH levels.

Sign in / Sign up

Export Citation Format

Share Document