Zinc Ash Research Articles

Numerical study of gas-solid two-phase flow in the snout of continuous hot-dip galvanizing process

In the hot-dip galvanizing process for strip steel, zinc vapor oxidizes and forms zinc ash in the snout. Given that the snout connects the annealing furnace, the zinc ash will return to the annealing furnace with the gas, affecting the upstream process. The gas-solid two-phase flow regularity in the snout is the key issue for zinc ash control. In this paper, the snout of a hot-dip galvanizing production line was taken as the physical model. The two-phase flow was simulated by the Euler-Lagrange method and the zinc ash particles were simulated via the discrete phase model (DPM). The results show that several vortex regions exist in the snout due to the forced convection caused by the moving strip and changes in flow channel sizes. There exist differences in the movement of zinc ash with different diameters. Small zinc ash has a strong tracking performance with the gas. Large zinc ash is easy to remain in the snout. In addition, orthogonal analysis was conducted to determine the optimal parameter combination. The research results provide theoretical guidance for the operation scheme of the gas circulation system.

Utilization of Galvanizing Flue Dust Residue: A Sustainable Approach towards Complete Material Recycling

During hot-dip galvanization, wastes such as bottom dross, zinc ash, spent pre-treatment solutions, and galvanizing flue dust (GFD) are generated. In scientific publications, research devoted to GFD waste recycling is absent, and companies generating this waste require a solution to this complex problem. GFD is often landfilled in hazardous waste landfills. However, it is possible to process this waste hydrometallurgically, where GFD is first leached, the solution is refined, and finally, zinc metal is obtained by electrowinning. During specific environmentally friendly leaching, not all solid GFD is dissolved, and the aim of this study is to process the remaining solid GFD residue. The analysis shows that the GFD residue material mainly contains zinc (42.46%) in the form of oxides, but there is also a small amount of polluting elements such as Al, Fe, and Pb. This study examines the leaching of the samples in HCl and H2SO4 under different conditions with the aim of obtaining a solution with a high concentration and high leaching efficiency of zinc. The L/S ratio of 3, 4 M H2SO4, and ambient temperature proved to be optimal for the leaching of the GFD residue, where 96.24% of zinc was leached out, which represents a zinc concentration of 136.532 g/L.

ANALYSIS OF THE STRUCTURE OF INDUSTRIAL WASTE USED TO CREATE NEW COMPOSITE MATERIALS

During the production of silicon, a significant amount of waste is generated, namely micro- and nanosilica. Micro- and nanosilica, with its properties and structure, immediately interested scientists in many countries from the point of view of processing this material into a new product with unique functional properties. The article presents the results of studies of waste from various industries - microsilica, as a waste of silicon production, zinc ash - a waste of the hot-dip galvanizing process, and abrasive powder - a waste of metal machining. To study waste from various industries, the authors used the method of electron microscopy as the simplest and fastest way to transmit information about the microstructure, elemental composition and grain size distribution. A comparative analysis of the microstructures and properties of these materials was carried out in order to better understand the nature and predict the possibility of their further use as initial components for the production of new composite materials. Keywords: microsilica, zinc ash, microstructure, waste disposal, composite material, properties of new materials.

IMPLEMENTATION OF THE ZINC RECOVERY SYSTEM FOR THE CONTINUOUS HOT-DIP GALVANIZATION PROCESS.

This article aims to carry out a study on the reuse of zinc ash produced during galvanization, produced on the surface of the tank due to zinc oxidation, and the slag from the flux-zinc-iron reaction, which needs to be removed so as not to harm the process. of galvanization. With the increase in zinc and thinking about sustainability and recycling, a furnace was developed with a rotating cylinder that is heated using a NG burner, to reuse the zinc from its ashes. A financial comparison was prepared, aiming to show the differences between using the zinc recycling furnace and selling this waste. From the analyzes of zinc ash and zinc recycled by the prototype, a concentration of 40% Zn in the ash and a purity of 99.35% of Zn in the recycling process can be obtained, making it ideal for reuse.

Irradiation time dependent of the ZnO/GO composite formation on the photodegradation of Rhodamine B

Rhodamine B (Rh B) is one of the dyes used in the dyeing of paints, acrylic, and fabrics as well as biological products. A high concentration of Rh B is highly toxic and dangerous to living organisms when directly discharged into water. Therefore, in this study, the degradation of Rh B in water by zinc oxide/graphene oxide (ZnO/GO) composite was investigated. The zinc oxide (ZnO) was recovered from zinc ash, waste from galvanization industries, by acid leaching process using hydrochloric acid (HCl), while the graphene oxide (GO) was synthesized by modified Hummers method. The nanocomposite of ZnO/GO was synthesized using microwave irradiation and characterized by means of Field Emission Scanning Electron Microscope (FE-SEM), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FTIR). The effect of irradiation time during ZnO/GO nanocomposite formation on the photocatalysis activity of the ZnO/GO in degrading Rhodamine B under UV rays was studied. The irradiation time was varied for 6, 8, and 10 minutes. The characterization results confirm that ZnO, GO, and ZnO/GO have been successfully synthesized. The ZnO/GO nanocomposite was also responsive to UV rays and able to degrade Rh B, as one of the examples of water pollutants. The highest degradation of Rhodamine B is achieved by the ZnO/GO nanocomposite prepared at 10 minutes of irradiation. The results of this study demonstrate that microwave irradiation time affects the ability of the nanocomposite to degrade Rhodamine B.

Zinc ash deposition pattern and structural optimization in the continuous hot-dip galvanizing vertical furnace

In a continuous hot-dip galvanizing vertical furnace for strip steel, zinc vapor oxidizes in the snout of the furnace to form zinc ash. The zinc ash adheres and agglomerates on the inner walls of the snout. If the zinc ash falls off and adheres to the surface of the strip, zinc ash defects will be formed, thereby affecting the surface quality of the galvanized layer. Given that the snout connects the annealing furnace and the zinc pot, the zinc ash will be transported into the annealing furnace and form nodulation on the roller, affecting the normal operation of the equipment. To study the deposition pattern of zinc ash inside the snout, a model of particle movement and deposition is established in this work to predict the movement and deposition characteristics of zinc ash particles, and it is verified by literature. On this basis, the zinc ash deposition patterns of three improvement cases of snout structure are compared. Results show that all three improvement schemes can effectively reduce the deposition rate of the zinc ash particles in the annealing furnace. In the case of slotted-baffle-added-only, although adding slotted baffles reduces the deposition of zinc ash in the furnace, it also increases the deposition rate in the snout and entry sections. In the case of exhaust-duct-added-only, the addition of the exhaust duct not only reduces the overall deposition rate in the furnace, but also effectively reduces the deposition rate in the snout and the entry section. By contrast, the scheme with slotted baffles and exhaust ducts is the most effective in inhibiting the diffusion of zinc ash.

Feasibility Study on Automation of Zinc Ash Skimming Process in Batch Galvanising

The aim of the presented feasibility study was to systematically investigate the automation of the skimming (i.e., removal) of zinc ash from the surface of the zinc bath in order to minimise the risks for workers due to mechanical hazards (risk of falling into the zinc kettle) and chemical hazards (inhalation exposure to zinc vapours) by eliminating this activity. As part of the feasibility study, automatic separation and skimming systems from various applications, such as removal systems of slags and metal foam, were identified. For this purpose, their technical feasibility and suitability were considered. Two automated techniques, a mechanical and a gas-based skimming system, were selected for the subsequent laboratory-based evaluation. In the scope of the practical feasibility study, the selected skimming techniques were designed, constructed, and evaluated based on near-process prototype tests on a laboratory scale. The focus was on the efficiency of the skimming systems, related to the removal of zinc ash from the free surface of the molten zinc (general efficiency), as well as to the zinc ash removal with a simulated attachment system of the samples to be galvanised (task-related efficiency). The desired complete removal of zinc ash from the zinc bath surface was demonstrated with two automated methods: a pulse wave method of the mechanical skimming system and a gas-based skimming system in general, operating independently from the attachment system. Additionally, as part of the process-related simulation of the complete batch galvanising process, a fully automated combination of the zinc ash skimming and extraction system was achieved on a laboratory scale.

Ammoniacal leaching behavior and regularity of zinc ash

AbstractIn this work, a new hydrometallurgical process was developed to treat zinc ash produced from the hot galvanizing industry. The theoretical analysis shows the feasibility of dissolving zinc ash in the NH3–NH4Cl–H2O system, and the dissolution products are predominantly composed of Zn (NH3)42+. The impacts of different experimental conditions were examined, and the leaching ratio of zinc was as high as 96.4% under the conditions of NH3/NH4+ratio of 1:1, liquid/solid of 9:1, total ammonia concentration of 8 mol/L and the stirring speed of 250 rpm at 313 K for 120 min. The kinetics of the leaching process were investigated and the calculated apparent activation energy was approximately 4.69 kJ/mol, which indicated that the zinc ash leaching process was controlled by diffusion-controlled. As revealed by the determination of impurity ions, on one hand, there were fewer impurities in the leaching solution, and the concentrations of Fe2+and Pb2+in solution are less than 0.02 mg/L and 0.05 mg/L respectively; on the other hand, there was no need for further impurity removal in this process. The proposed process has a certain application value in treating zinc ash.

A New Process of Direct Zinc Oxide Production by Carbothermal Reduction of Zinc Ash.

Zinc ash is a by-product of the hot-dip galvanizing process and the electrolytic zinc process, which is classified as a hazardous waste consisting predominately of zinc oxide that could be recovered as the useful main resource for ZnO preparation. In this work, in order to reduce the energy consumption of the direct reduction process and improve the resource-recovery rate. A new technology for zinc oxide production, by a carbothermal reduction of zinc ash, is proposed. This process includes two steps: high-temperature roasting of zinc ash for dechlorination and a carbothermal reduction of dechlorination ash. Zn in zinc ash is mainly presented in the form of zinc oxide (ZnO), basic zinc chloride (Zn5(OH)8Cl2H2O), and metallic zinc (Zn). Basic zinc chloride can be roasted and decomposed to reduce the chlorine content in zinc ash. The results of a chloride ion removal test show that the optimal roasting temperature is 1000 °C, with a holding time of 60 min. Under the modified conditions, the chloride content in the roasted zinc ash is reduced to 0.021 wt.%, and the dechlorination rate is more than 99.5%, which can meet the requirements of zinc oxide production. The best process conditions for zinc oxide production by carbothermic reduction are as follows: reduction temperature of 1250 °C, reduction time of 60 min, and reduction agent addition of 22 wt.%. Under the best reduction process, the purity of zinc oxide product is 99.5%, and the recovery of zinc is more than 99.25%. Needle-like zinc oxide obtained by carbothermic reduction has high purity and can replace zinc oxide produced by an indirect process.

Investigating the use of zinc production wastes as filler in asphalt mixtures

This study aimed to evaluate different types of zinc production wastes for using as filler in asphalt mixtures. Four different types of waste, namely, leach cake, nickel cake, cobalt cake and zinc ash have been chosen along with limestone powder as the control filler for evaluation. Elemental analysis of the fillers, the rheological properties of the mastics and some mechanical properties of the mixtures using Marshall and indirect tensile strength (ITS) tests and their environmental effects using Toxicity Characteristic Leaching Procedure (TCLP) and Synthetic Precipitation Leaching Procedure (SPLP) tests have been investigated. Results show that, except the nickel cake, for which the cadmium concentration exceeds the legal limit, rest of the fillers can be used as filler in asphalt concrete. The zinc ash filler results in much better performance than the other fillers. Leach and cobalt cake are found to be hydrophilic with low resistance against moisture damage.

Effects of using white flour, zinc oxide and zinc ash as an admixture in mortar and concrete

This paper focuses on finding out both environment friendly and easily available admixture for concrete. Admixtures are property modifying compounds used in construction industry. They can be added both at production or during batching. Admixtures can be used to alter various properties of concrete namely compressive strength, workability, setting time, crack resistance, durability, permeability etc. Effect of an admixture usually vary with the characteristics of cement used and proportion in which it is mixed. Starch can be used as an admixture in concrete. In this study white flour, zinc oxide and zinc ash which consists of about 80 to 90% zinc oxide was used. various percentages of white flour were added in replacement with cement and was found that the setting time of concrete/ cement increases with the addition of starch admixtures. Compressive strength of concrete increases with the increase in percentage of white flour until 1%. Any further increase in in white flour causes decrease in strength of concrete. Thus, starch admixtures namely white flour can be used instead of chemical admixtures, thereby reducing the additional cost incurred while using chemical admixtures. Also zinc ash which consists mainly of zinc oxide is tested for its use as an admixture in concrete. zinc ash is a waste product of zinc manufacturing industry. By effectively using it in concrete both safe disposal of waste material and required admixture property in concrete could be achieved. It was found that addition of zinc oxide greatly increases the compressive strength of concrete about 20%.

Pertanggungjawaban Pidana Korporasi terhadap Pemalsuan Data Ekspor Zinc Ash yang Dilakukan oleh PT Marakes Jaya Abadi di KPPBC Belawan

This article discusses the legal rules governing corporate liability in laws and regulations against falsification of zinc ash export data, and how the factors that cause zinc ash data falsification by corporations and how the criminal law policies against corporations falsify export data. The method used in this paper is a normative legal research method. Normative legal research is the study of legal materials, both primary legal materials and secondary legal materials. The factors causing the falsification of zinc ash data by corporations are as follows: The factors causing the falsification of customs documents, among others are: (a) Geographic, (b) Production market, (c) Society. Efforts to tackle the crime of falsifying export data by the Belawan Intermediate Customs and Excise Investigation and Customs Enforcement Team (KPPBC TMP) in Belawan have reflected both ways of countermeasures, namely the repressive penal route and the preventive non-penal route.

Determination of Titanium in Zinc ash by FAAS After Digested using Ultrasound-Assisted Extraction

In this study, it is aimed to determine the amount of Ti (titanium) in waste ash samples taken from galvanizing factories by using flame atomic absorption (FAAS). Various time periods and different solvent mixtures were examined by using ultrasound-assisted extraction for digestion of zinch ash which taken from various processes of galvanizing metal sheet or pipe. The best solvent mixtures for Ti metal in galvanized waste was found HCl:HNO3:H2O2 (1:3:2) > HCl > HNO3:HCl (1:3) > HNO3 > HNO3:H2SO4 (3:1) > HNO3:H2SO4 (1:1) > HNO3:H2SO4 (3:2) > HNO3:H2SO4 (2:1), respectively.

Adsorption of Orange II Onto Zn2Al–Layered Double Hydroxide Prepared From Zinc Ash

The dye industry is one of the largest water consuming industries, and at the same time generates large quantities of wastewaters. The resulting wastewaters require proper treatment before discharge, because the dye contents have a negative effect on the water body and organisms present in it. The most efficient treatment method for water containing dyes is represented by adsorption processes. The challenge with these adsorption processes is to develop new, efficient, viable, and economic adsorbent materials. Therefore, in the present paper, the performance of Zn2Al-layered double hydroxide, prepared from an industrial waste (zinc ash) as a zinc source, was investigated in the Orange II dye adsorption process. The Zn2Al-layered double hydroxide prepared from secondary sources presents similar morphological and structural characteristics as those prepared from analytical grade reagents. The influence of initial dye concentration, adsorption time, solid:liquid ratio, pH, and temperature was evaluated in order to confirm the benefit of this waste valorization. A comparison with the reference Zn2Al-layered double hydroxide prepared from analytical grade reagents was performed and the results show that due to the small presence of impurities, the material prepared from zinc ash shows better adsorption capacities (qmax,exp = 42.5 mg/g at 293 K) than the material prepared from reagents (qmax,exp = 36.9 mg/g at 293 K), justifying the utilization of secondary sources for layered double hydroxides preparation. The proposed treatment process presents advantages from both economic and environmental protection point of view.

Evaluating the properties of zinc production wastes as filler and their effects on asphalt mastic

This study evaluated four types of zinc production waste and limestone powder to be used as filler in asphalt mixtures. The properties of the fillers, asphalt mastic and mixtures made by the fillers were investigated. Only the results for fillers and mastics are provided. The physical and chemical properties and morphology of waste fillers, namely cobalt cake, leach cake, nickel cake, and zinc ash, as well as the limestone powder, as control filler, were examined. The moisture content, particle and bulk density, methylene blue value (MBV), Rigden voids (RV), pH, chemical compositions, morphology, hydrophobicity, size distribution, solubility in water, and specific surface area of the fillers were evaluated. Also, using a constant volumetric filler to binder ratio, asphalt mastics were made and their softening point, ductility, penetration grade and rheological properties were measured and compared with neat binder. Evaluation of the properties of fillers showed that the fillers can be potentially used in asphalt mixtures. Zinc ash had comparable and even better properties than the control filler. In terms of hydrophobicity, solubility in water and moisture content, the best performance belonged to zinc ash, followed by limestone, nickel, cobalt, and leach cake, respectively. Leach and cobalt cake showed to be hydrophilic fillers. The lowest MBV was found for the zinc ash, followed by limestone, nickel, leach and cobalt cake. The highest RV was found for the leach cake, and lowest for zinc ash filler. The fillers have different levels of stiffening effect on the mastic. In terms of temperature susceptibility using the softening point test results, the lowest sensitivity was obtained for zinc ash followed by cobalt cake, leach cake, limestone, and nickel cake. However, penetration and DSR test results revealed that the highest stiffening effect was obtained using zinc ash followed by cobalt cake, nickel cake, limestone, and leach cake. The stiffening effect of the fillers can be described by the morphology of filler particles; however, RV cannot be directly related to the stiffening effect of the fillers.

Hydrometallurgical recovery of zinc from industrial hot dipping top ash

Abstract Top ash from hot-dip galvanizing plant was investigated as a source of secondary zinc to be returned to galvanizing bath. The waste material contained 63% Zn as metallic, oxide and hydroxychloride phases. It was leached in H2SO4 solutions (20% and 25%) at various bath loadings (100−300 g/L). Leaching behaviors of zinc, manganese, iron and chloride ions were investigated. A few strategies of iron elimination from leaching liquors were examined. Flocculant addition was harmful for subsequent filtration of iron precipitates due to increased viscosity of solution, while a combination of zinc oxide and calcium carbonate for rising pH resulted in the formation of dense suspension unenforceable to separate from zinc sulphate solution. Zinc electrowinning was carried out at different pH (from −0.5 to 2.8) using a range of current densities (3−10 A/dm2). Optimal conditions for pure metal recovery were: leaching in 20% H2SO4 solution at zinc ash content 100−150 g/L, Fe2O3·xH2O precipitation using H2O2 and CaCO3, zinc electrowinning at pH of 0.1−1.0 at 3−6 A/dm2. Correlations between pH and free H2SO4 concentration in electrolyte solutions were also discussed. pH−acid concentration dependence for zinc electrolyte was between experimental and calculated curves for pure H2SO4 solutions, while the curve was shifted towards lower pH if ferric ions were in the solution.

Rheology of Self-Compacting Concrete Nanocomposites

In the current research work the fresh properties (filling and passing ability, and resistance to segregation of self-compacted concrete (SCC) are investigated with the nanocomposite particles. Under the scope of the research work, the rheological parameters of the fresh self-compacting concrete (SCC) fused with nano sized Blasting Grit (nBG) (average particle size 500 nm) and rod like Zinc Ash (nZA) (average particle size 300 nm) are analyzed. In the scope of the work nZA and nBG are fused in Pozzolana Portland Cement (PPC) and Fine Aggregate (FA) respectively, for 0%, 0.25%, 0.5% and 0.75% by weight of material. The rheological behavior of SCC like filling ability, passing ability and segregation resistance are studied for the modification in SCC. The result shows significance of the material and test method used in this experiment. The output of the experiment shows that the rate of fusing of nZA and nBG in ingredients of the concrete contributes in rheological and mechanical properties of SCC. For the validation of the experimental results the statistical models also prepared, the regression model, ANOVA model and Correlation model gives the importance of the ingredients used along with selected test for the work. The current research is useful for developing zinc ash and blasting grit as a building material. The outcomes of the experiments are more important in a fresh stage of the SCC which was developed as a sustainable way with the good flowing ability.

Investigation of industrial waste materials for hydrometallurgical recovery of zinc

Three industrial waste materials were examined in terms of their elemental and phase compositions, leaching behaviour in sulphuric acid solutions followed by solution purification and zinc electrowinning. Two dusts being mixtures of metallic zinc and zinc oxide of various proportions and zinc ash, containing simonkolleite additionally, were used. All materials characterized with high zinc percentages (60–80%). Zinc extraction from the materials was high (89–99% in 25% H2SO4) after short time of leaching. In all cases transfer of zinc ions to the leachate was accompanied by different levels of solution contamination in iron, manganese and chloride ions. Leaching of the materials was an exothermic process. Precipitation purification was carried out by using traditional method (oxidation followed by alkalization with CaCO3). Electrolysis parameters (current efficiency, voltage, energy consumption) were typical for zinc electrowinning, but surface morphology of zinc deposits was affected by chloride ions in the electrolyte.

Recovery of zinc from zinc ash by leaching in sulphuric acid and electrowinning

Oxide fraction of zinc ash originating from hot dip galvanizing plant was investigated. Chemical and phase compositions of the material were characterized in details. The zinc ash contained simonkolleite, zinc oxide and metallic zinc as main phases. Influence of solid to liquid ratio (150–500 kg/m3) and sulphuric acid concentration (20% and 25%) on dissolution of zinc and metallic impurities was investigated. 95–97% zinc recovery was obtained for 150–200 kg/m3 in 20% H2SO4, but the solutions were contaminated mainly by Mn(II) and Fe(II, III) ions. Acid leaching of the zinc ash was accompanied by exothermic effects. Precipitation purification of the leach liquor from iron ions was followed by zinc electrowinning. Final product of 99.5% purity at a current efficiency of 92% was obtained.

Zinc recovery from waste zinc ash - A new “green” route for the preparation of Zn-Al layered double hydroxide used for molybdate retention

The aim of this paper is to study the synthesis of a Zn-Al layered double hydroxide using a waste as an alternative source of zinc, namely the zinc ash resulted from hot dip galvanizing process. The zinc ash was treated with hydrochloric acid to obtain zinc chloride solution, which was subjected to a purification process. The layered double hydroxide was synthesized by a co-precipitation method at low oversaturation. The as-obtained (LDH) and calcined at 450 °C (CLDH) adsorbents were used in the removal process of molybdate from water. Both materials were subjected to structural and morphological characterization. The as-synthesized product has characteristics close to those of the material obtained from analytical grade reagents. The kinetic study of the adsorption showed that the process followed accurately a pseudo-second order kinetics (correlation coefficients > 0.99). The results concerning the process equilibrium showed that CLDH exhibited higher efficiency (maximum adsorption capacity of 39.8 mg/g) in the adsorption of Mo(VI) from aqueous solutions than LDH (13.7 mg/g), which is in accordance with their specific surface area. The mechanism of molybdate uptake follows inner-sphere surface complexation. These materials obtained from a secondary resource are quite efficient in the removal process of molybdate anions from aqueous solutions, as compared to other adsorbents obtained from expensive analytical grade reagents reported in the literature.