Selective Leaching Method Research Articles

Enrichment of low-grade phosphorites by the selective leaching method

Abstract The selective leaching method presents a new and innovative approach for the enrichment of low-grade phosphate raw materials. The use of acetic acid as a reagent in the leaching process allows for the selective dissolution of carbonates, potassium-, and aluminum-containing compounds, offering a promising solution for the improvement of the recovery rates of valuable phosphorus compounds. This study presents the results of research on the selective leaching of carbonates from low-grade phosphate raw materials and evaluation of its efficiency using a combination of SEM, energy-dispersion and chemical analysis, X-ray diffraction, differential thermal, IR-Fourier spectroscopic, and mineralogical analysis techniques. The results showed an increase in the content of phosphorus(v) oxide from 14% to 22% through the selective leaching process. The enriched phosphate raw materials were also found to be suitable for the production of phosphorus-containing products. This research highlights the potential of the selective leaching method to overcome the challenges faced in the enrichment of low-grade phosphorites and provide a more efficient and sustainable solution for the industry.

Arsenic in polish coals: Content, mode of occurrence, and distribution during coal combustion process

The research presented in the paper allowed the determination of the content and mode of arsenic occurrence in Polish commercial coal. The selective leaching method showed that in the case of the examined samples, As in coal occurred mostly with mineral matter (mainly with carbonates, sulphates, and disulphides). In addition, a study of As distribution in the combustion process of the coals was conducted at temperatures of 800 °C, 1000 °C, and 1200 °C. The amount of As that, during combustion, passed to gas was affected by the parameters of the combustion process (temperature and combustion rate) and chemical composition of the coals. Moreover, statistical analysis showed that the amount of Asgas in the flue gas is significantly influenced by the presence of this toxic element in coal mainly in association with disulphides (pyrite), carbonates, and sulphates. In addition to the research methods, statistical analysis based on significance assessment was used.

Reusing industrial iron wastes in production of ferrous Sulphate that utilizes in manufacturing of food supplements by selective leaching method

After do the research in variety sources for get some information about food supplement which belong to ferrous Sulphate and how can get this material that got from industrial material waste by selective leaching method, by reaction between industrial waste of iron with sulfuric acid. Iron waste used here got from work shop. After preparation these wastes then processing and recycling by dissolving these industrial wastes in sulfuric acid. According to standard diagrams of X-ray diffraction (XRD) for ferrous Sulphate found that results of ferrous Sulphate are conformable. Besides hydrogen gas was resulted from that reaction as by-product and utilizable. Thereupon the environment protection from industrial wastes will be done. In addition, this method does not consume electrical energy, and industrial iron waste is invested in it instead of using expensive iron ores, meaning it is an economical method that supports the environment and sustainability.

Next generation technology for utilization of alumina rich iron ore tailings in India

Abstract Accumulation of low-grade iron ore tailings (IOTs) generated during the processing of high-grade iron ore has become a great threat to environment. Although wide range of research works has carried out to recover the iron values from the IOTs, but the solid recovery value has limited to ca. 50% in Indian context. In order to attain a maximum iron recovery and to utilize these solid wastes for future needs, an attention has shed on the topics of hydrometallurgy and applied nanomaterial synthesis from IOTs. Iron containing nanoparticles (ICNs) have huge potential in environmental and energy related applications. A wide range of synthesis methods has developed to produce ICNs from the mine waste. It is evident from the recent research works that converting waste materials into value added products are gaining more attentions. Objective of this review is to analyse the green synthesis routes to prepare ICNs from mine waste, starting from the physio chemical identification of waste material followed by discussion on various methods of ICNs synthesis routes from mine waste. It includes selective leaching method. Finally, the use of ICNs for environmental application had discussed in brief

Selective leaching of vanadium in calcification-roasted vanadium slag by ammonium carbonate

Calcification roasting is a clean way to extract vanadium from the vanadium slag. But the subsequent sulfuric acid leaching brings the impurity of phosphorous into the leach liquor of vanadium and thus inhibits the precipitation of vanadates for vanadium recovery. In this paper, a novel selective leaching method using ammonium carbonate ((NH4)2CO3) has been proposed for the extraction of vanadium in the calcification-roasted vanadium slag. The (NH4)2CO3 leaching can dissolve calcium vanadates with high selectivity while maintaining other impurities including phosphorous in the solid residue. Ammonium vanadate can be precipitated directly by cooling down without pH adjustment or ammonium salt addition, which makes the (NH4)2CO3 leaching cost-effective. The waste water after precipitation can be recycled back to the leaching circuit, showing the friendliness of (NH4)2CO3 leaching method to the environment. With (NH4)2CO3 leaching, 96.0% of vanadium can be dissolved while the corresponding leaching efficiency of phosphorous is 9.2% using the most suitable condition of solid/liquid ratio 1:20, particle size 45–74μm, leaching temperature 80°C, (NH4)2CO3 concentration 600g/L and leaching time 70min. This work has laid the foundation for the industrial application of ammonium carbonate leaching and provided new insights into selective leaching of valuable elements in complex minerals.

YREE scavenging in seawater: A new look at an old model

In the ocean, yttrium and the rare earth elements (YREEs) show nutrient-like vertical profiles. Since the YREEs have no manifest biological function, their removal from solution (scavenging) is probably caused by sorption on particles rather than active microbial uptake, yet the exact nature of these particles is uncertain. An existing theoretical model describes scavenging as an equilibrium between complexation with dissolved inorganic ligands and with functional groups on particle surfaces. This model was able to predict input-normalized (i.e., shale-normalized) YREE abundance patterns in seawater without requiring poorly known parameters like particle concentrations or the site densities of functional groups. Employing well-established stabilities of inorganic YREE complexes, while assuming that the sorbent particles are organic with functional groups represented by a mixture of simple monocarboxylic acids, it reproduced some key features of seawater YREE patterns, specifically the characteristic increase of shale-normalized abundance with atomic number and distinctive anomalies of certain trivalent REEs (La and Gd). The familiar negative Ce anomaly of seawater, however, is due to redox reactions that were not explicitly accounted for.In this study, we refined calculations of YREE solution speciation by adding complexation with desferrioxamine B to gauge the influence of strong organic ligands prevalent near the ocean surface. The scavenging model was then inverted by subtracting high-quality YREE abundance patterns, reported for the open ocean, from this solution speciation to yield an average pattern of relative YREE affinities for the sorbent particles. The resulting affinity pattern is compared with patterns of distribution coefficients, derived from laboratory experiments, for YREE sorption on relevant solid phases including hydrated Fe and Mn oxides (HFO/HMO), calcite, and the green macroalga Ulva lactuca as a substitute for marine organic matter. For deep seawater, the best agreement is observed with HMO, which may thus be the dominant carrier of YREEs to the sediment. Since Ce is catalytically oxidized on manganese oxide surfaces, this could have implications for the evolution of the Ce anomaly. Direct comparisons of distribution coefficient patterns with YREE analyses of suspended particles from the Atlantic Ocean also favor HMO, but this may be dictated in one case by the use of a selective leaching method. For shallow seawater, particularly in the Atlantic Ocean, the best agreement is observed with U. lactuca and calcite, although the latter is offset by the low YREE contents of this biogenic mineral. Matches with HFO are generally less convincing. The aforementioned mixture of simple monocarboxylic acids is not a good proxy for the sorptive properties of marine organic matter.

Preparation of Metallic Nanoparticles

Nanomaterials are substances with high application potential. It this article, the preparation technique are reviewed with aiming on selective leaching method. This method is based on preparation of conviniet binary alloy in form of supersaturated solid solution and consequent matrix dissolution. In the same time, the minor element forms nanoparticles. The need of rapid solidification of binary precursor before leaching is explained. Nanoparticles from Ni and Ag prepared by selective leaching form AlNi20 and MgAg10 alloys, were characterized by X-ray diffraction and by electron microscopy (SEM and TEM).

Pigmentary properties of rutile TiO2 modified with cerium, phosphorus, potassium, and aluminium

AbstractThe influence of different modifiers, phosphorus, potassium, aluminium, and cerium on the pigmentary properties of TiO2 was studied. The phase composition and distribution of modifiers in prepared TiO2 products was investigated using XRD analysis, the selective leaching method, and ICP-AES technique. The optical properties, photoactivity, morphology, and surface area of modified TiO2 were determined by spectrophotometric, fluorescent, SEM, and BET measurements. The research was directed towards obtaining a pigmentary TiO2 with the highest possible photostability. It was found that the final calcination temperature, at which the anatase-rutile transformation rate was > 97 %, depended on the kind and amount of the modifiers introduced into hydrated titanium dioxide. In comparing the colour of TiO2 products modified with Ce, it was found that the addition of K to the TiO2 series caused an increase in all the optical properties examined. The presence of K and Al in TiO2 modified with Ce resulted in decreased photocatalytic activity. The photostability of TiO2 modified with Ce and K improved with an increase in P2O5 content. The highest photostability was measured for the TiO2-CePKAl series. It was concluded that the differences in both the optical properties and photoactivity of TiO2 depended on its phase composition and the distribution of modifiers in the products obtained.

Photostability and optical properties of modified titanium dioxide

The influence of different modifiers, P2O5, K2O, Al2O3, SiO2, CeO2, and ZrO2, on the optical properties and photostability of rutile titanium dioxide was studied. The research was aimed at obtaining pigmentary rutile titanium dioxide with the enhanced photostability. The optical properties such as brightness, white tone, and gray tone were improved when titanium dioxide samples were modified with zirconium instead of cerium. Titanium dioxide products modified additionally with Al2O3 displayed improved optical properties by comparison with appropriate titanium dioxide products lacking introduced aluminum. In comparison with unmodified material (∆E * = 21.8), a considerable increase of the photostability of modified titanium dioxide was observed. The lowest photoactivity, in the range of ∆E * = 0.96–2.45, was measured for the TiO2-PKAlSiCe series. A selective leaching method and X-ray diffraction (XRD) analysis were used to determine the distribution of modifiers in titanium dioxide materials. It was concluded that the differences in both photoactivity and optical properties of modified titanium dioxide depend on its phase composition.

Distribution of Additives in Single-Modified TiO2

ABSTRACTIn the present work the influence of different modifiers, calculated to B2O3, CeO2, Sb2O3, ZnO, and ZrO2, on their distribution in TiO2 is investigated. The phase composition and phase transformation of prepared rutile-TiO2 is determined by the selective leaching method, ICP-AES, XRD and FT-IR techniques. The addition of Sb2O3 to TiO2 has no influence on the anatase–rutile phase transformation, CeO2 and ZrO2 act as inhibitors of the TiO2 phase transformation and the addition of ZnO or B2O3 to TiO2 accelerates rutile formation. It is observed that boron is located in TiO2 in the form of soluble B2O3, zinc partly reacts with titanium forming co-phase TiZn2O4 and antimony addition to TiO2 presumably causing the formation of a co-phase of Sb with Ti. Cerium forms a separate phase, CeO2, and reacts partly with titanium, probably creating co-phase, CexTi(1-x)O2 (for example Ce0.8Ti0.2O2). Zirconium addition in TiO2 forms separate ZrO2 phase and solid solution of Zr with Ti.

Kinetics study for photodegradation of methylene blue dye by titanium dioxide powder prepared by selective leaching method

The kinetics of photodegradation of methylene blue (MB) dye by titanium dioxide (TiO 2) powder were investigated using elementary reactions. TiO 2 powders were prepared by a selective leaching method consisted of processes of CaHPO 4 precipitation, heat treatment, and acid leaching to obtain high crystalline anatase. The obtained TiO 2 samples had wide ranges of specific surface areas (5–23 m 2/g) and densities of Ti 3+ defects (90–480×10 12spin/g) without a significant change in the anatase phase ratio ranging 0.86–0.91 in mass ratio. The MB photodegradation rate was expressed as functions of specific surface area and density of Ti 3+ defects under the experimental condition that the photodegradation rate was proportional to UV irradiation intensity and the adsorbed MB amount was proportional to specific surface area. A proposed equation for calculation of photodegradation ate demonstrated greater effect of specific surface area than density of Ti 3+ defects for MB photodegradation.

Preparation and Characterization of Single-Modified TiO2 for Pigmentary Applications

In the present work the influence of different additives, calculated to ZrO2, ZnO, and B2O3, on the anatase–rutile phase transformation was investigated. The chemical composition of prepared titania samples was determined by the selective leaching method, powder X-ray diffraction analysis, and FT-IR measurements. The effect of small amounts of additives on the optical properties, photoactivity, and surface area of rutile-phased TiO2 for pigmentary applications was examined using spectrophotometer, SEM, and BET measurements. ZrO2 acted as an inhibitor of the TiO2 phase transformation and the addition of ZnO or B2O3 to TiO2 accelerated rutile formation at 750 °C. ZrO2 addition in TiO2 could form separate ZrO2 phase and solid solution of Zr with Ti. Zinc partly reacted with titanium forming cophase TiZn2O4. Boron was located in TiO2 in the form of soluble compound, B2O3. Almost all optical properties were lower for modified TiO2 in comparison with the corresponding unmodified sample. The SBET increased with ...

Removal of Phosphorus From High Phosphorus Iron Ores by Selective HCl Leaching Method

The selective HCl leaching method was used to remove phosphorus from high phosphorus iron ores. The hydroxyapatite in high phosphorus iron ores was converted into soluble phosphate during the process of HCl leaching. The effects of reaction time, particle size, hydrochloric acid concentration, reaction temperature, liquid-solid ratio and stirring strength on the dephosphorization ratio were studied. The results showed that the dephosphorization ratio can exceed 98% under the conditions of reaction time 30 – 45 min, particle size <0.147 mm, hydrochloric acid concentration 2.5 mol/L, reaction temperature 25 °C, liquid-solid ratio 5:1 and stirring strength 5.02 – 12.76 s −1. After dephosphorization reaction, the content of phosphorus in iron ore complied completely with the requirements of steel production.

Effect of CeO2 and Sb2O3 on the phase transformation and optical properties of photostable titanium dioxide

AbstractIn the present work, the effect of individual additives calculated as molar fractions of Sb2O3 and CeO2 (x Sb 2O3 range: 0.03–0.08 %, x CeO 2 range: 0.05–0.14 %), on the phase composition, phase transformation, and optical properties of photostable rutile titanium dioxide was studied using selective leaching method, ICP-AES technique, XRD method, spectrophotometric analysis and S BET measurements. The starting material was hydrated titanium dioxide. It was observed that the addition of Sb2O3 to TiO2 did not influence the anatase-rutile phase transformation, but increasing the CeO2 addition caused a decrease in the rutilization degree. Thus, CeO2 acted as an inhibitor of the TiO2 phase transformation. Sb2O3 addition to TiO2 presumably caused the formation of a co-phase of Sb with Ti. Cerium formed a separate phase, CeO2, and reacted partly with titanium, probably creating co-phase, Ce0.8Ti0.2O2. Comparing the colour of modified rutile titanium dioxide according to the type of the additive introduced, it was found that TiO2 with CeO2 had higher brightness but lower white tone values when compared with TiO2 modified with Sb2O3. The relative lightening power and grey tone of the modified TiO2 were higher in TiO2 modified with Sb2O3. The values of the photocatalytic activity measured in all TiO2 samples modified either with Sb2O3 or CeO2 were very similar and varied around the value of 21.

Porous Biodegradable Scaffold: Predetermined Porosity by Dissolution of Poly(ester‐anhydride) Fibers from Polyester Matrix

A novel selective leaching method for the porogenization of the biodegradable scaffolds was developed. Continuous, predetermined pore structure was prepared by dissolving fast eroding poly(epsilon-caprolactone)-based poly(ester-anhydride) fibers from the photo-crosslinked poly(epsilon-caprolactone) matrix. The porogen fibers dissolved in the phosphate buffer (pH 7.4, 37 degrees C) within a week, resulting in the porosity that replicated exactly the single fiber dimensions and the overall arrangement of the fibers. The amount of the porosity, estimated with micro-CT, corresponded with the initial amount of the fibers. The potential to include bioactive agents in the porogen fibers was demonstrated with the bioactive glass.

Preparation of highly porous silica nanocomposites from clay mineral: a new approach using pillaring method combined with selective leaching

A silica xerogel was synthesized from a clay mineral by a new approach using a pillaring method combined with a selective leaching method. Preparation was conducted by applying an HCl/ethanol treatment after intercalation and condensation of tetraethoxysilane (TEOS) and/or methyltriethoxysilane (MTS) into cetyltrimethylammonium (CTA) ion-exchanged vermiculite. The products are porous nanocomposites consisting of TEOS and/or MTS-derived polysiloxane and hydrated silica, resulting from the selective leaching process of the inorganic constituents and the extraction of CTA ions from CTA-exchanged vermiculite after the intercalation of TEOS and/or MTS. The morphology remains similar to the originated vermiculite owing to the topotactic dissolution process. The products have high porosity with 1205–715 m 2 g −1 of BET surface area when prepared with up to 2 mol dm −3 HCl concentration. The pore size distributions of the products show a wide distribution from 1 nm to 4 nm in diameter due to the presence of micropores and mesopores. The HCl concentration dependence of the surface area suggests that the main porosity arises from the porous polysiloxane which is formed by the pillaring process. Water adsorption isotherms reveal that the products have a hydrophilic surface originating from silanol groups on the polysiloxane and the hydrated silica. However, the incorporation of MTS in the pillaring process results in successful surface modification of the products. This novel approach is advantageous for the synthesis of highly porous xerogels with different kinds of surface properties.

Characterization of U series nuclides in geological materials by selective leaching method

Geological and geochemical events were elucidated in by using U series nuclides in combination with chemical leaching technique. Two examples were examined: (1) in the apatite-bearing sediment column samples U(VI) is moving, while U(IV) in the samples is almost retained, and (2) the redistribution of U occurred along the column under the monsoon climate. On the other hand, U in the conglomerate sample is divided into 5 categories by the leaching technique, which are related with exchangeable, carbonate, iron oxide, organic/sulfide and silicate components, respectively. Uranium is shown to be abundant in the carbonate and iron rich fractions of conglomerate sediment. Appropriate models are proposed in each case study.

Porous Properties of γ-Alumina/Potassium Aluminosilicate Gel Composites Prepared by Selective Leaching and Precipitation Method

Composites of mesoporous γ-alumina and potassium aluminosilicate (KAS) gel were prepared by selective leaching of calcined kaolinite using KOH solution followed by neutralization of the solution at pH 5.5 with nitric acid. The porous properties of the composites were characterized by N2 gas adsorption and their microtextures were observed by electron microscope. The resultant composites have specific surface areas of about 290 m2/g, pore sizes of about 1.85 nm in radius and pore volumes of about 0.5 ml/g. The porous properties of the composites are compared with those of γ-alumina and KAS gel.

Selective Leaching for the Preparation of Functional Porous Ceramics

Preparation of various porous ceramics by selective leaching method and their properties were summa rized and reviewed in this paper. Porous ceramics can be prepared utilizing variety of composite microtextures and crystal structures. Using interconnected microtexture in phase separated glasses formed by spinodal decomposition, porous glasses have been prepared and used for filter materials because they have crack free piercing pores in uniform size and good mechanical strength. Porous materials can be also prepared using nanocomposite microtextures formed by phase separation, crystallization and etc. In these porous materials, pores were formed by selective leaching of amorphous matrix. Since very fine nanocrystalline grains were spatially separated and exposed in the surface of pores, various interesting prop erties were obtained. Porous materials with unique porous properties can be prepared by selective leaching method from crystals with characteristic structures such as chain, layered and framework utilizing solubility difference in various components.

Preparation of Firing Bodies from Mesoporous Materials by Selective Leaching Method and Its Water Vapor Adsorption. (Part 2).

To investigate the possibility of developing a humidity self-control material, mesoporous-powder prepared by selective leaching method was pressed and fired with adding organic binders. A comparison was carried out with a material fired with clay binder. The specific surface area, total pore volume, pore size distribution, and water vapor adsorption of the fired bodies were measured for samples prepared at various firing temperatures, to evaluate the humidity controlling properties. The amount of water vapor adsorbed by the fired bodies decreased with increasing the firing temperature of the bodies. The amount of water adsorption on the body fired at 900°C (GK33-900) at a relative humidity between 30 and 60%, and between 60 and 90% was, however, similar to that of the original powder. It was found that the dry pressing process with organic binders was more suitable than that with clay binders and it was possible to manufacture the fired body preserving the humidity self-control property.