scholarly journals Chemical Characterization and Leaching Kinetics of Metals From Iron Ores

2019 ◽  
pp. 69-80
Author(s):  
Itodo A. U. Itodo A. U. ◽  
Eneji I. S. Eneji I. S. ◽  
Mnenga B. O. Mnenga B. O. ◽  
Tseen M. A. Tseen M. A.
Keyword(s):  
Acidic Medium ◽  
Iron Ore ◽  
Atmospheric Environment ◽  
Basic Medium ◽  
Pollution Indices ◽  
Iron Ores ◽  
Leaching Kinetics ◽  
Mineralogical Characterization ◽  
The Impact ◽  
Kinetics Of

The impact of mineral deposit on their host agricultural soil, available water bodies and near atmospheric environment is of great concern. In this study, mineralogical characterization and leaching kinetics of metals from iron ores in Kogi States, were reported. Physicochemical parameters namely; electrical density, pH, bulk density and moisture content were also investigated. The SEM image of the iron ore appear compact with irregular shape. XRF analysis showed that, iron ore consist of 63.44 % Fe as major element, with the oxide composition of 90.71%. The XRD analysis of iron ore unveiled the presence of magnetite (88 %), hematite (9 %) and quartz (3 %) as associated mineral. Low concentration of iron (0.77-1.70 ppm) was observed to be leached from iron ore in the acidic medium, 0.35-1.10 ppm from basic medium and 0.32-0.88 ppm in the aqueous medium, The Shrinking core, Product-layer diffusion and leaching, controlled by diffusion were the three equations used to model the leaching parameters. The leaching experimental data of iron ore fit best into the diffusion- controlled model, with R2 = 0.94 for the acidic medium Hence, the rate determining step. The analysis shows good fit for the other kinetic models. Overall, result proved that, the environment around mining sites is chiefly contaminated by the metals leached from the ore (mineral) deposits. Hence, the need to monitor the pollution indices, the role of leaching, pollutant fate (transport and reaction) and the subsequent distribution of metals to neighboring environment.

Etude cinétique des systèmes Cu(II)•Adénosine et Cu(II)•D-Ribose

1972 ◽  
Vol 50 (19) ◽  
pp. 3117-3123 ◽  
Author(s):  
G. Boivin ◽  
M. Zador
Keyword(s):  
Kinetic Parameters ◽  
Acidic Medium ◽  
Temperature Jump ◽  
Strong Acid ◽  
Basic Medium ◽  
Stopped Flow ◽  
Acid Solutions ◽  
Flow Method ◽  
Kinetics Of ◽  
Adenine Base

The kinetics of the formation and dissociation of Cu(II) complexes of adenosine have been determined in acidic and basic medium. In acidic medium, the complex is formed between the Cu(II) and the adenine base and the kinetic parameters have been obtained in this case using a temperature jump method. In basic medium, only the dissociation of the complexes could be studied by a stopped-flow method, by addition of EDTA or strong acid solutions. In these complexes, Cu(II) is bridged with ribose hydroxyls. Finally, D-ribose has also been studied for comparison in the same conditions. The mechanism of these reactions is discussed.

scholarly journals Application of dry high-intensity magnetic separation in upgrading low-grade iron ore of Rouina deposit, Algeria

2020 ◽  
Vol 56 (1) ◽  
pp. 47-58
Author(s):  
A. Messai ◽  
A. Idres ◽  
J.M. Menendez-Aguado
Keyword(s):  
Magnetic Separation ◽  
High Intensity ◽  
Iron Ore ◽  
Size Fraction ◽  
Cement Industry ◽  
Raw Material ◽  
Low Grade ◽  
Iron Ores ◽  
Mineralogical Characterization ◽  
Recent Developments

The recent developments of steel and iron industries generated a huge consumption of iron ores which has attracted much attention for utilizing low-grade iron resources to satisfy this increasing demand. The present study focuses on the characterization and enrichment of the low-grade iron ores from Rouina deposit-Ain Defla-. Currently, the ore is used in the cement industry because it is considered a low-grade iron ore. After the sampling process, a physico-chemical and mineralogical characterization was carried out and the results revealed that the sample consists of hematite, limonite and goethite as major opaque oxide minerals whereas silicates as well as clays form the gangue minerals in the sample. The average grade of FeTotal, SiO2 and Al2O3 contents in the raw material collected from the mine of the case study are 30.85%, 23.12% and 7.77% respectively. Processes involving combination of classification, washing and dry high-intensity magnetic separation were carried out to upgrade the low-grade iron ore sample to make it suitable as a marketable product. The sample was first ground and each closed size sieve fractions were subjected to washing followed by drying than dry high intensity magnetic separation and it was observed that limited upgradation is possible. As a result, it was possible to obtain a magnetic concentrate of 54.09% with a recovery degree of 89.30% and yield of 62.82% using a magnetic field intensity equal to 2.4 Tesla at the size fraction [-0.125 +0.063 mm].

scholarly journals Studies on the Kinetics of Doxazosin Degradation in Simulated Environmental Conditions and Selected Advanced Oxidation Processes

Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 1001 ◽  
Author(s):  
Joanna Karpinska ◽  
Aneta Sokol ◽  
Jolanta Koldys ◽  
Artur Ratkiewicz
Keyword(s):  
Environmental Conditions ◽  
Density Functional ◽  
Natural Waters ◽  
Basic Medium ◽  
Mechanistic Study ◽  
Aqueous Environment ◽  
Functional Theory ◽  
Short Time ◽  
The Impact ◽  
Kinetics Of

The photochemical behavior of doxazosin (DOX) in simulated environmental conditions using natural waters taken from local rivers as a solvent was studied. The chemical characteristics of applied waters was done and a correlation analysis was used to explain the impact of individual parameters of matrix on the rate of the DOX degradation. It was stated that DOX is a photoliable compound in an aqueous environment. Its degradation is promoted by basic medium, presence of environmentally important ions such as Cl−, NO3−, SO42− and organic matter. The kinetics of DOX reactions with OH− and SO4− radicals were examined individually. The UV/H2O2, classical Fenton and photo-Fenton processes, were applied for the generation of hydroxyl radicals while the UV/VIS:Fe2(SO4)3:Na2SO2 system was employed for production of SO4− radicals. The obtained results pointed that photo-Fenton, as well as UV/VIS:Fe2(SO4)3:Na2SO2, are very reactive in ratio to DOX, leading to its complete degradation in a short time. A quantitative density functional theory (DFT) mechanistic study was carried out in order to explain the molecular mechanism of DOX degradation using the GAUSSIAN 09 program.

Leaching kinetics of vanadium from calcification roasting converter vanadium slag in acidic medium

2018 ◽  
Vol 6 (4) ◽  
pp. 5119-5124 ◽  
Author(s):  
Hao Peng ◽  
Jing Guo ◽  
Xiaogang Zheng ◽  
Zuohua Liu ◽  
Changyuan Tao
Keyword(s):  
Acidic Medium ◽  
Leaching Kinetics ◽  
Vanadium Slag ◽  
Kinetics Of

scholarly journals A Review on the Kinetics of Iron Ore Reduction by Hydrogen

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7540
Author(s):  
Aidin Heidari ◽  
Niusha Niknahad ◽  
Mikko Iljana ◽  
Timo Fabritius
Keyword(s):  
Flow Rate ◽  
Iron Ore ◽  
Reduction Rate ◽  
Oxide Particle ◽  
Steel Production ◽  
Clean Energy ◽  
Critical Parameters ◽  
Iron Oxide Particle ◽  
The Impact ◽  
Kinetics Of

A clean energy revolution is occurring across the world. As iron and steelmaking have a tremendous impact on the amount of CO2 emissions, there is an increasing attraction towards improving the green footprint of iron and steel production. Among reducing agents, hydrogen has shown a great potential to be replaced with fossil fuels and to decarbonize the steelmaking processes. Although hydrogen is in great supply on earth, extracting pure H2 from its compound is costly. Therefore, it is crucial to calculate the partial pressure of H2 with the aid of reduction reaction kinetics to limit the costs. This review summarizes the studies of critical parameters to determine the kinetics of reduction. The variables considered were temperature, iron ore type (magnetite, hematite, goethite), H2/CO ratio, porosity, flow rate, the concentration of diluent (He, Ar, N2), gas utility, annealing before reduction, and pressure. In fact, increasing temperature, H2/CO ratio, hydrogen flow rate and hematite percentage in feed leads to a higher reduction rate. In addition, the controlling kinetics models and the impact of the mentioned parameters on them investigated and compared, concluding chemical reaction at the interfaces and diffusion of hydrogen through the iron oxide particle are the most common kinetics controlling models.

Beneficiation of rejects slime of iron ore by means of sequential leaching

2019 ◽  
Vol 116 (2) ◽  
pp. 202 ◽  
Author(s):  
Santanu Sarkar ◽  
Supriya Sarkar
Keyword(s):  
Hydrofluoric Acid ◽  
Iron Ore ◽  
Research Work ◽  
Shrinking Core Model ◽  
Leaching Kinetics ◽  
Iron Recovery ◽  
Weight Percentage ◽  
Leach Rate ◽  
Shrinking Core ◽  
Kinetics Of

The present research work has been conducted to remove gangue contents from rejects slime of iron ore, having particle size < 20 µm by circulating leaching with aqueous hydrofluoric acid (HF) followed by nitric acid (HNO3) washing. Effects of acid concentration, slurry ratio, reaction time, stirring speed and temperature on gangue removal have been examined. The gangue contents (alumina and silica) are reduced from 13 weight percentage (wt.%) to around 1 wt.%. The iron value has also been increased from 58.74 wt.% to 68.47 wt.% with more than 95% iron recovery. The gangue matter remaining after leaching consists mainly of aluminium and silicon, which is most likely encapsulated in the goethite phase. The leaching kinetics has also been studied to establish an overall leach-rate equation. The shrinking core model is very suitable to describe the kinetics of gangue removal.

Kinetics of hydrolysis of peroxodisulphate ions in acidic medium to peroxomonosulphuric acid

1981 ◽  
Vol 46 (5) ◽  
pp. 1229-1236 ◽  
Author(s):  
Jan Balej ◽  
Milada Thumová
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Acidic Medium ◽  
Measured Data ◽  
Molar Ratios ◽  
Starting Solution ◽  
Kinetics Of Hydrolysis ◽  
Rate Of Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

The rate of hydrolysis of S2O82- ions in acidic medium to peroxomonosulphuric acid was measured at 20 and 30 °C. The composition of the starting solution corresponded to the anolyte flowing out from an electrolyser for production of this acid or its ammonium salt at various degrees of conversion and starting molar ratios of sulphuric acid to ammonium sulphate. The measured data served to calculate the rate constants at both temperatures on the basis of the earlier proposed mechanism of the hydrolysis, and their dependence on the ionic strength was studied.

scholarly journals Spatial Variation of Water Chemistry in Aries River Catchment Western Romania

2021 ◽  
Vol 11 (14) ◽  
pp. 6592
Author(s):  
Ana Moldovan ◽  
Maria-Alexandra Hoaghia ◽  
Anamaria Iulia Török ◽  
Marius Roman ◽  
Ionut Cornel Mirea ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Water Quality ◽  
Water Chemistry ◽  
Water Samples ◽  
Mine Drainage ◽  
Pollution Indices ◽  
Mining Activities ◽  
River Catchment ◽  
High Concentrations ◽  
The Impact

This study aims to investigate the quality and vulnerability of surface water (Aries River catchment) in order to identify the impact of past mining activities. For this purpose, the pollution and water quality indices, Piper and Durov plots, as well vulnerability modeling maps were used. The obtained results indicate that the water samples were contaminated with As, Fe, Mn, Pb and have relatively high concentrations of SO42−, HCO3−, TDS, Ca, K, Mg and high values for the electrical conductivity. Possible sources of the high content of chemicals could be the natural processes or the inputs of the mine drainage. Generally, according to the pollution indices, which were correlated to high concentrations of heavy metals, especially with Pb, Fe and Mn, the water samples were characterized by heavy metals pollution. The water quality index classified the studied water samples into five different classes of quality, namely: unsuitable for drinking, poor, medium, good and excellent quality. Similarly, medium, high and very high vulnerability classes were observed. The Durov and Piper plots classified the waters into Mg-HCO3− and Ca-Cl− types. The past and present mining activities clearly change the water chemistry and alter the quality of the Aries River, with the water requiring specific treatments before use.

Study on leaching kinetics of hexavalent chromium from aged calcium-free chromium slag

2021 ◽  
pp. 1-13
Author(s):  
Quan Qi ◽  
Liang Li ◽  
Liangyu Wei ◽  
Baoming Hu ◽  
Zheng Liu ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Resource Utilization ◽  
Scientific Basis ◽  
Diffusion Reaction ◽  
Leaching Kinetics ◽  
Leaching Rate ◽  
Chromium Slag ◽  
Leaching Solution ◽  
Main Components ◽  
Kinetics Of

To provide a scientific basis for the resource utilization of chromium slag, this article studies the release law of hexavalent chromium in the aged calcium-free chromium slag. XRD (X-ray diffractometer) and MLA (Mineral Liberation Analyzer) were used to analyze the composition of the chromium slag; using sulfuric acid-nitric acid as the leaching solution, the release law of hexavalent chromium in chromium slag and the leaching kinetics were studied. The results show that main components of the chromium slag are magnesioferrite, chromite, hematite, hydrargillite, and spinel; chromium is mainly present in chromite and magnesioferrite; the leaching rate of hexavalent chromium increases with the increase of temperature or the decrease of pH. The analysis of leaching kinetics shows the leaching rate is controlled by the internal diffusion reaction, and the apparent activation energy is 11.93 kJ·mol–1. The chromium slag is aged in high temperature seasons, which is conducive to the precipitation of hexavalent chromium in the chromium slag, can increase the yield of chromate in the roasting kiln, and is conducive to resource utilization; chromium slag should be stored in order to prevent acid rain erosion which leads to environmental pollution risk (e.g. drinking water).

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