scholarly journals The Investigation of Optimizing Leaching Efficiency of Al in Secondary Aluminum Dross via Pretreatment Operations

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1269
Author(s):  
Haigang Feng ◽  
Guofan Zhang ◽  
Qun Yang ◽  
Luobing Xun ◽  
Siyuan Zhen ◽  
...  
Keyword(s):  
Chemical Interaction ◽  
Acid Leaching ◽  
Scanning Electron Micrographs ◽  
Water Leaching ◽  
Secondary Aluminum ◽  
Aluminum Dross ◽  
Process Mineralogy ◽  
Leaching Experiments ◽  
Physical And Chemical ◽  
Leaching Efficiency

Secondary aluminum dross (SAD) is an inevitable by-product from the secondary aluminum industry and has caused serious environmental issues. In this study, the effect of pretreatment operations on the subsequent acid leaching operation was studied by process mineralogy, a series of leaching experiments, XRD, and SEM. Leaching results showed that the leaching efficiency of Al in direct acid leaching was only 22.99%. Process mineralogy showed the complex intertexture and continuous network structure in the SAD. Pretreatment operations were extremely efficient in destroying the structure by physical and chemical interaction. Interestingly, by adding the grinding and water leaching operations, the leaching efficiency of total aluminum in the SAD reached approximately 28.70%. XRD results showed that nearly all metallic Al, AlN, and partial Al2O3 were leached by grinding–water leaching–acid leaching. The scanning electron micrographs showed that the residue particles mainly included some insoluble components and had a smooth surface.

scholarly journals Recovery of Zinc and Silver from Zinc Acid-Leaching Residues with Reduction of Their Environmental Impact Using a Novel Water Leaching-Flotation Process

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 586
Author(s):  
Yunpeng Du ◽  
Xiong Tong ◽  
Xian Xie ◽  
Wenjie Zhang ◽  
Hanxu Yang ◽  
...  
Keyword(s):  
Hazardous Waste ◽  
Acid Leaching ◽  
Copper Recovery ◽  
Water Leaching ◽  
Flotation Process ◽  
Metal Levels ◽  
Valuable Metals ◽  
Leaching Experiments ◽  
Zinc Hydrometallurgy ◽  
Poor Stability

Zinc-leaching residue (ZLR) is a strongly acidic hazardous waste; it has poor stability, high heavy metal levels, and releases toxic elements into the environment. ZLR has potential as a valuable resource, because it contains elevated levels of zinc and silver. In this paper, the recovery of zinc (Zn) and silver (Ag) from ZLR wastes from zinc hydrometallurgy workshops using water leaching followed by flotation was studied. During water leaching experiments, the zinc and copper recovery rates were 38% and 61%, respectively. Thereafter, various flotation testing parameters were optimized and included grinding time, reagent dosages, pulp density, flotation time, and type of adjuster. Experimental results demonstrated this flotation method successfully recycled Ag and Zn. A froth product containing more than 9256.41 g/t Ag and 12.26% Zn was produced from the ZLR with approximately 80.32% Ag and 42.88% Zn recoveries. The toxicity characteristic leaching procedure (TCLP) results indicated the water-leaching flotation process not only recycled valuable metals such as zinc and silver in zinc-containing hazardous wastes but lowered the hazardous waste levels to those of general wastes and recycled wastes in an efficient, economical, and environmentally friendly way.

Recovery of Zinc from Municipal Solid Waste Incineration Fly Ash

2021 ◽  
Vol 13 (5) ◽  
pp. 956-965
Author(s):  
Chen-Piao Yen ◽  
Yun-Hwei Shen ◽  
Kai-Lun Chiu ◽  
Hsin-Hsiang Huang
Keyword(s):  
Fly Ash ◽  
Chemical Properties ◽  
Acid Leaching ◽  
Physical And Chemical Properties ◽  
Water Leaching ◽  
X Ray ◽  
Msw Incineration ◽  
Physical And Chemical ◽  
Target Metal ◽  
And Chemical Properties

In recent years, over one million tons of Municipal Solid Waste (MSW) incineration fly ash has been generated annually Taiwan. Only a small percentage of the ash was used as raw material for other utilities besides landfill. Fly ash contains many harmful heavy metals, such as Cd and Cr, among others; however, fly ash also contains many valuable metals, including as Zn, Pb, and Ga.To recover Zn from fly ash, in this work, an experiment was first designed to determine the physical and chemical properties of the fly ash. Then, treatment processes, including water leaching, acid leaching, and ion exchange were conducted.Test samples were subjected to scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence spectrometer (XRF), and atomic absorption spectroscopy (AAS) to determine their physical and chemical properties. Then, water leaching was conducted under optimal experimental conditions. Thereafter, acid leaching was performed using two different acids (hydrochloric and sulfuric) to extract the target metal ions, and finally the ion exchange process was deployed to concentrate and recover the target metal ions.Ultimately, an optimal process to recover zinc from MSW incineration fly ash was developed in this work. An aqueous solution containing approximately 1 wt% zinc was obtained by leaching with sulfuric acid. Zn was then concentrated using a chelating resin IRC-747 in column mode.

scholarly journals Synthesis of Cryolite (Na3AlF6) from Secondary Aluminum Dross Generated in the Aluminum Recycling Process

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3871
Author(s):  
Bingbing Wan ◽  
Wenfang Li ◽  
Wanting Sun ◽  
Fangfang Liu ◽  
Bin Chen ◽  
...  
Keyword(s):  
National Standard ◽  
Molar Ratio ◽  
Recycling Process ◽  
Water Leaching ◽  
Secondary Aluminum ◽  
Co2 Gas ◽  
Aluminum Dross ◽  
Aluminum Recycling ◽  
Ignition Loss ◽  
Polyhedral Shape

Secondary aluminum dross (SAD) is regarded as a solid waste of aluminum recycling process that creates serious environmental and health concerns. However, SAD can also be used as a good source of aluminum, so that utilizing the SAD for the production of valuable products is a promising approach of recycling such waste. In the present work, a novel eco-friendly three-step process was proposed for the synthesis of cryolite (Na3AlF6) from the SAD, and it consisted of (1) water-washing pretreatment of SAD, (2) extraction of Al component via pyro-hydrometallurgy, including low-temperature alkaline smelting, water leaching and purification of leachate in sequence, (3) precipitation of cryolite from the purified NaAlO2 solution using the carbonation method. By analysis of the parameter optimization for each procedure, it was found that the maximum hydrolysis efficiency of aluminum nitride (AlN) in the SAD was around 68.3% accompanied with an extraction efficiency of Al reaching 91.5%. On this basis, the cryolite of high quality was synthesized under the following optimal carbonation conditions: reaction temperature of 75 °C, NaAlO2 concentration of 0.11 mol/L, F/(6Al) molar ratio of 1.10, and 99.99% CO2 gas pressure, and flow rate of 0.2 MPa and 0.5 L/min respectively. The formation of Na3AlF6 phase can be detected by XRD. The morphological feature observed by SEM revealed that the as-synthesized cryolite had a polyhedral shape (~1 μm size) with obvious agglomeration. The chemical composition and ignition loss of the as-synthesized cryolite complied well with the requirements of the Chinese national standard (GB/T 4291-2017).

scholarly journals Characterization of Spent Ni-MH Batteries

2012 ◽  
Vol 730-732 ◽  
pp. 569-574
Author(s):  
Marta Cabral ◽  
Fernanda Margarido ◽  
Carlos A. Nogueira
Keyword(s):  
Quantitative Analysis ◽  
Electrode Materials ◽  
Phase Identification ◽  
Recycling Process ◽  
X Ray ◽  
Leaching Experiments ◽  
Plastic Components ◽  
Definition Of ◽  
Physical And Chemical

Spent Ni-MH batteries are not considered too dangerous for the environment, but they have a considerable economical value due to the chemical composition of electrodes which are highly concentrated in metals. The present work aimed at the physical and chemical characterisation of spent cylindrical and thin prismatic Ni-MH batteries, contributing for a better definition of the recycling process of these spent products. The electrode materials correspond to more than 50% of the batteries weight and contain essentially nickel and rare earths (RE), and other secondary elements (Co, Mn, Al). The remaining components are the steel parts from the external case and supporting grids (near 30%) containing Fe and Ni, and the plastic components (<10%). Elemental quantitative analysis showed that the electrodes are highly concentrated in metals. Phase identification by X-ray powder diffraction combined with chemical analysis and leaching experiments allowed advancing the electrode materials composition. The cathode is essentially constituted by 6% metallic Ni, 66% Ni(OH)2, 4.3% Co(OH)2 and the anode consists mainly in 62% RENi5 and 17% of substitutes and/or additives such as Co, Mn and Al.

Recovery Technology of Zinc from Hydrometallurgical Zinc Residues

2011 ◽  
Vol 396-398 ◽  
pp. 620-623
Author(s):  
Ya Li Zhang ◽  
Xian Jin Yu ◽  
Xiao Na Guo ◽  
Xiao Bin Li
Keyword(s):  
Acid Leaching ◽  
Optimum Conditions ◽  
Water Leaching ◽  
Zn Content

In this work, it was aimed to select and propose a feasible as well as an applicable method, or series of methods for the extraction of zinc. After determination of the components of the residue, water leaching, acid leaching and roasting-leaching were performed to reclaim Zn. Roasting-leaching was found to be effectively for Zn extraction by controlling acid mass, roasting duration and temperature as parameters. At the optimum conditions, 0.7 times the amount of H2SO4 at 250 °C for 150 min in roasting, 82.05% of initial Zn content was extracted.

PREPARATION, EVALUATION AND OPTIMIZATION OF MUCOADHESIVE MINI TABLETS OF TELMISARTAN BY USING SINGLE UNIT ENCAPSULATION SYSTEM

INDIAN DRUGS ◽  
2019 ◽  
pp. 64-67
Author(s):  
Indrajeet S. Patil ◽  
Omkar A. Patil ◽  
Rohankumar R. Chavan ◽  
Dheeraj S. Randive ◽  
Mangesh A. Bhutkar ◽  
...  
Keyword(s):  
Drug Release ◽  
Single Unit ◽  
Chemical Interaction ◽  
Extended Period ◽  
Controlled Drug Release ◽  
Wet Granulation ◽  
Dissolution Study ◽  
Capsule Shell ◽  
Physical And Chemical

The objective of the present study was to develop and optimize capsule filled oral mucoadhesive minitablets of telmisartan. Wet granulation method was employed for the development of minitablets. All the formulations (F1- F13) exhibited more than 21% drug release at 4h and at the end of 12h it showed drug release more than 90%. During the dissolution study it was observed that the capsule shell in which the minitablets were filled got completely dissolved in the first 5 min. FTIR and UV study showed absence of any significant physical and chemical interaction between drug and polymers. Formulation F 10 was found to possess higher drug release at 4h and 12 h. Combination of HPMC and Carbopol was found to be suitable for formulation of mucoadhesive minitablets, showed promising mucoadhesive strength and exhibited controlled drug release over an extended period of time.

Leaching kinetics of copper and valuable metal extraction from copper-cadmium residues of zinc hydrometallurgy by oxidation acid leaching

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jihao Guo ◽  
Hongao Xu ◽  
Bo Li ◽  
Yonggang Wei ◽  
Hua Wang
Keyword(s):  
Hydrogen Peroxide ◽  
Acid Concentration ◽  
Acid Leaching ◽  
Metal Extraction ◽  
Agitation Rate ◽  
Leaching Kinetics ◽  
Solid Ratio ◽  
Zinc Hydrometallurgy ◽  
Kinetics Of ◽  
Leaching Efficiency

Abstract Multiple purification of zinc sulfate solution is an important process for zinc hydrometallurgy, and large quantities of copper-cadmium residues are generated as byproducts in this process. Copper-cadmium residues contain a large number of valuable metals that must be recovered. A comprehensive extraction process has been proposed using sulfuric acid as the leaching reagent and hydrogen peroxide as the oxidizing reagent. The effects of acid concentration, leaching temperature, leaching time, liquid-to-solid ratio, hydrogen peroxide dosage and stirring speed on the leaching efficiency were investigated. The optimum conditions were determined as an acid concentration of 150 g/L, liquid-to-solid ratio of 4:1, hydrogen peroxide amount of 20 mL, time of 60 min, temperature of 30 °C, particle size of −d75 μm, and agitation rate of 300 r/min. It was concluded that the leaching efficiency of copper and cadmium reached 97%, but because of the existence of zinc sulfide in the residues, a lower leaching efficiency of zinc was obtained. Furthermore, the leaching kinetics of copper was also studied based on the shrinking core model. The activation energy for copper leaching was 5.06 kJ/mol, and the leaching process was controlled by the diffusion through the product layer.

scholarly journals Medidas de adesão entre agregado e ligante asfáltico

TRANSPORTES ◽  
2008 ◽  
Vol 16 (1) ◽  
Author(s):  
Kamilla Lima Vasconcelos ◽  
Amit Bhasin ◽  
Dallas N. Little ◽  
Jorge Barbosa Soares
Keyword(s):  
Chemical Interaction ◽  
Asphalt Binder ◽  
Fatigue Cracking ◽  
Adhesion Measurement ◽  
Materials Used ◽  
Enthalpy Of Immersion ◽  
Physical And Chemical ◽  
Energy Components

<p>A adesão entre agregado e ligante asfáltico vem sendo apontada como uma propriedade de grande importância para a causa de defeitos encontrados em pavimentos asfálticos, tais como trincas por fadiga, e dano por umidade. Diferentes mecanismos existem na literatura para explicar a adesão entre os dois materiais, porém, estes mecanismos podem ser resumidos em três grandes grupos: inter- travamento mecânico, adesão física, e interação química. A ocorrência de mais de um mecanismo simultaneamente parece ser o fenô- meno mais provável, sendo a relevância de cada um dependente das características físicas e químicas do agregado e do ligante asfálti- co. No presente trabalho, dois procedimentos foram utilizados para acessar a adesão entre agregado e ligante. O primeiro constou do cálculo do trabalho de adesão através da energia livre de superfície dos materiais envolvidos e o segundo, da determinação da entalpia de imersão quando soluções de asfalto são postas em contato com o agregado. Todos os materiais usados foram provenientes da biblio- teca de referência do SHRP sendo um pedregulho como agregado, e três diferentes ligantes asfálticos. Os resultados mostraram a capa- cidade do microcalorímetro em detectar possíveis interações químicas na adesão entre agregado e ligante asfáltico, em conjunto com adesão física. A presença de grupos funcionais mais fortemente adsorvidos pela superfície dos agregados justificou os maiores valores de entalpia de imersão para as combinações onde esses grupos se encontravam presentes.</p><p><em><strong>Abstract</strong> Adhesion between the asphalt binder and the aggregate is critical to the performance and durability of asphalt mixtures. According to the literature, distresses mechanisms such as fatigue cracking and moisture induced damage are correlated to the nature and quality of adhesion between these two materials. Different mechanisms already exist to explain adhesion, but they can be summa- rized in three main groups: mechanical interlocking, physical adhesion and chemical interaction. Although discussions of isolated theo- ries and mechanisms help to clarify the understanding of adhesion, they can rarely be separated completely to each other. The physical and chemical characteristics of asphalt and aggregate will in fact determine the relevance of each of these mechanisms. This study presents the results of two procedures for adhesion measurement: (i) an indirect method based on the surface free energy components of asphalt binder and aggregate; and (ii) the determination of the enthalpy of immersion through the use of a microcalorimeter. The materials used, a gravel as aggregate and three different neat asphalts, were provided by the Strategic Highway Research Program's Material Reference Library. The results showed the capacity of the microcalorimeter in detecting possible chemical reactions together with physical adhesion. The presence of functional groups more strongly adsorbed by the aggregate surface justified the higher values of the heat of immersion. </em></p>

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