Waste Zinc Research Articles

Basic scheme of copper and zinc waste recycling in metallurgical brass production

The article proposes a recycling scheme for dusty waste generated during the metallurgical brass production with the use of two-stage leaching. During the first stage, when the dust is dissolved by a 0,5 mol/l sulfuric acid solution, a product solution containing the major amount of zinc ions (0,46 mol/l) and a small amount of copper ions (less than 0,02 mol/l) is obtained. Copper is sequentially electrochemically isolated from this solution, at a current density of 0,1 A/dm2, and then zinc is isolated at 5,0 A/dm2. The dry residue (cake) is subjected to copper-ammonia leaching, as a result of which all copper passes into the solution, and associated metals remain undissolved. In order to extract copper from the resulting solution, the liquid extraction by a 0,34 mol/l DH-510A solution in kerosene is used. Copper ions are extracted from the organic phase through re-extraction by a 2,0 mol/l sulfuric acid solution. The cathode copper is extracted from the obtained sulfuric acid electrolyte at current density of 1,5–2,0 A/dm2. The advantages of the proposed scheme are the increase in environmental friendliness through the use of solution recirculation at all stages of the process, as well as waste minimization through the entire process of dusty metallurgical sludge recycling.

Dairy Wastewater for Production of Chelated Biodegradable Zn Micronutrient Fertilizers

Zinc containing organic materials were synthesized using dairy wastewater and solid zinc waste derived from zinc nitrate with the goal of obtaining biodegradable, slow release, micronutrient containing fertilizers. The developed synthesis procedure involved heating at mild 55 °C temperature, followed by pH adjustment to 7, precipitation, and drying. The resulting solid materials were characterized using weight analysis, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Fourier transformed infrared spectroscopy (FTIR). Higher wastewater-to-zinc nitrate ratios of 1:1/5 yielded amorphous materials with no inorganic zinc compounds detected. TGA analysis showed very complex thermal behavior due to the large amount of organics present while FTIR analysis suggested the presence of both coordinated and uncoordinated carboxylic acid and ester groups. The developed process can have a variety of applications in recovering Zn from waste sources, such as tire crumb, while returning this valuable micronutrient into soil as a slow release biodegradable fertilizer.

Preparation for Ultra High Pure Indium Metal for Optoelectronic Applications

Ultra high pure Indium metal is extensively used in optoelectronic devices. Indium and its alloys become potential candidates in aerospace, defense and communication sectors. Purification of Indium has been done by Instrolec-200 Refiner followed by Directional Melting/ Freezing and Solidification Systems. Major targeted impurities are Metallic impurities Ag, Al, As, Bi, Ca, Cu, Fe, Ga, Ge, Mg, Pb, Sb, Si, Sn, and Zn. Purified Indium is characterized by analytical techniques Inductively Coupled Plasma- Optical Emission Spectrophotometry and Inductively Coupled Plasma- Mass Spectrometry. Keywords—Indium, Purification, Instrolec-200 Refiner, Metallic impurities I-INTRODUCTION: SPHALERITE ores, Lead and Tin circuits, Zinc Flue Dust and Waste Liquors from Indium Plating are main resources from which Indium metal is recovered. Indium is minor metal in the earth's crust but it has unique and versatile combination of properties, Low melting point (156.5987 o C) and high boiling point (2072 o C) (5) . At -269.63 o C Indium becomes superconductor which makes it very useful in Cryogenics applications (4) . Ultra high pure Indium is used in several applications. Purification of Indium is very foremost operation. In purification process, if the purity of starting material remains low then even by using perfect and appropriate method, Ultra high pure and device grade product is very difficult to achieve. Multi Pass vertical zone refining is employed for purification of 3N pure Indium which is followed by Directional Melting/ Freezing and Solidification System. Purification is done with respect to some targeted impurities like Ag, Al, As, Bi, Ca, Cu, Fe, GA, Ge, Mg, Pb, Sb, Si, Sn, Zn and the results are obtained.

ChemInform Abstract: Palladium‐Catalysed Coupling Reactions

AbstractReview: 116 refs.

Spent Oil Management and its Recycling Potential in India Inventory and Issues

In India, there are 36,165 industries, generating 62,32,507 Metric Tonnes of Hazardous Waste (HW) every year. However, Generation of recyclable HW is the highest in the country. Recyclable waste attributes to the dominant HW treatment option 49.55% followed by land disposable (43.78%) and incineration (6.67%) respectively. Under the Hazardous Wastes (Management, Handling & Transboundary Movement) Rules, 2008 the processes generating HW were finalized, yet the differentiation of quantum of HW generation based on types of HW i.e used/waste oil, lead waste, zinc waste etc. has been highlighted first of its kind as an inventory in the present study. There are about 257 Spent oil (Used/Waste Oil) registered recycling facilities distributed across 124 districts spread over 19 states in India with the total spent oil recycling capacity as 1.39 MMT. Thus India has a huge recycling potential with a greater yield while considering the generation of used oil and waste oil from automotive sector and manufacturing industries. The major constraint faced in recycling waste/used oil is cost of the collection, storage & subsequent transportation of the waste to the recycling unit.

Study on Application Potential of Waste Cake from Secondary Zinc Industry

Zinc extraction process generates hazardous waste cake during the recovery of electrolytic grade zinc and copper. The characteristics of the waste with reference to basic properties viz. ignitability, corrosivity, reactivity and EP toxicity are important parameters that define the magnitude of hazard of a waste. The waste under study falls under Schedule-I of Hazardous Waste (Management & Handling) Rules, 2003. The Toxicity Characteristics Leachate Procedure (TCLP) test was carried out for extraction of waste cake leachate and subsequently toxic heavy metals present in the waste were estimated. The physic-chemical parameters along with particle size analysis, differential thermal analysis and X-ray diffraction analysis were carried out which provide information on the major constituents present in the hazardous zinc waste cake before and after stabilisation/stabilisation of the waste. The approach would be helpful in safe disposal and exploring application potential of zinc waste through adoption of suitable binder mechanism.

Chromium (VI) and zinc (II) waste water co-treatment by forming layered double hydroxides: Mechanism discussion via two different processes and application in real plating water

Two processes, adsorption after synthesis (AAS) and adsorption during synthesis (ADS) were compared in CrO42− and Zn2+/CrO42− removal. Kinetic results showed that ADS was a better method than AAS, since Cr content was 0.65/0.81mmol/g in Cr-ADS/ZnCr-ADS, but it was only 0.37/0.56mmol/g in Cr-AAS/ZnCr-AAS. Then, a low-cost mixture was proposed to function as ADS raw materials in treating real plating waters. This mixture first got an isothermal saturation of 1.1mmol/g in simulated CrO42− water. When Zn2+ was co-treated, it was increased to 1.3mmol/g. At the same time, a Zn2+ removal of 1.5mmol/g was attained. Furthermore, real plating water co-treatment reached equilibrium in 6h and obtained 1.4/0.9mmol/g for Zn2+/CrO42−, respectively. According to XRD analysis, this co-treatment enhancement resulted from the formation of Zn and Cr contained layered double hydroxide.

Recovery of Zinc from the Final Slag of Steel's Galvanizing Process

With the rising cost of zinc reaching historic levels, more emphasis is being placed on technologies to increase the efficient utilization of zinc. One area targeted for increased efficiency is in-house recycling of metallic zinc industrial wastes. The largest consumer of zinc is the hot-dip galvanizing of steel. Large amount of zinc slag containing more than 50% zinc, are accumulated during galvanization processes at the surface of molten zinc bath and is usually skimmed manually. At First, The pyrometallurgical recovery of zinc from slag samples was carried out, and parameters affecting recovery processes such as time, temperature, and flux percentage were studied. The results obtained revealed that zinc metal is successfully recovered from these secondary resources. The recovery efficiency is 70% for zinc waste materials having a particle size diameter of + 1.25 mm. An optimum percentage of 25% weight of ammonium chloride fluxing agent was obtained. The optimum temperature for the recovery process was 700°C.

Arabidopsis arenosa (Brassicaceae) from a lead–zinc waste heap in southern Poland – a plant with high tolerance to heavy metals

The morphological traits and tolerance to heavy metals (zinc, cadmium and lead) of two populations of Arabidopsis arenosa (Brassicaceae) were compared. One population was from a zinc–lead waste heap in Boleslaw near Olkusz (southern Poland), the other one from the Kampinoski National Park (central Poland). Biometric measurements were done in the field and repeated after cultivation under controlled conditions (garden soil, phytotron chamber). Significant heritable morphological differences between the two populations were found. The plants from the waste-heap are smaller in comparison with the reference population, and their leaves are narrower, thicker with fewer trichomes, indicating. genetic adaptation to xerothermic conditions. The level of tolerance to heavy metals (zinc, cadmium, and lead) was compared by the root test. Very high tolerance to the three metals tested was found in the waste-heap population. Its tolerance exceeded that of four other predominant plant species populations growing on the same waste heap that had previously been tested in our laboratory. We consider the waste-heap population of A. arenosa to be a very suitable ecotype for the study of heavy metal tolerance mechanisms in plants.

Recovery of Zinc from Zinc Waste By-adsorption Process

Recovery of Zinc from Zinc Waste By-adsorption Process

Effectiveness of arbuscular mycorrhizal fungal (AMF) strains in colonisation of plants involved in phytostabilisation of zinc wastes

The effectiveness of mycorrhizal colonisation of four fungal isolates of different origin was tested in roots of Festuca rubra L. and Plantago lanceolata L. cultivated on three zinc waste substrata of different toxicity. F. rubra showed a much better survival rate than P. lanceolata. The effectiveness of mycorrhizal colonisation varied between the fungal isolates introduced. The highest values of the mycorrhizal parameters were found in roots inoculated with the Glomus claroideum strain originating from the industrial waste. Arbuscular richness, assessed in roots stained for viable fungal structures, was demonstrated to be the most sensitive parameter, showing statistically important differences between plants, artificially inoculated and those colonised only by the indigenous mycorrhizal fungi. This parameter was also useful to compare the substrata concerning their toxicity, and the results of the viability tests correlated well with the “availability” of the heavy metals.

Study of zinc in cementitious material stabilised/solidified wastes by sequential chemical extraction and microstructural analysis

In the present study, a five step sequential chemical extraction (SCE) procedure was employed to investigate the binding mechanisms and chemical partitioning of zinc in cement-based stabilised waste materials. After each step of SCE, scanning electronic microscope with energy dispersive spectrometer (SEM/EDS) and X-ray diffraction (XRD) were used to assess the microstructural and chemical changes of the waste materials. The results showed that the leaching of Zn from the cement based stabilised waste mainly took place at the second and the third extraction steps at pH 5.0 and 2.0, respectively. The addition of pulverised fly ash (PFA) increased the leachability of Zn at the second extraction step. The SCE results also indicated the hydration of cement was greatly retarded by the incorporation of zinc waste. The SEM and XRD analysis of the samples after each extraction step demonstrated that zinc leached at the second step extraction was partially due to the dissolution of the new crystalline phase (ZnO) in the waste materials. Since large amounts of zinc were leached out only at the third extraction step at pH 2.0, these stablised waste materials may be relatively stable under a normal disposal environment.

Hydrometallurgical Treatment of Zinc Waste Dusts

Abstract Hydrometallurgical separation processes offer attractive potential for recovery of marketable zinc from industrial wastes. In view of the importance of having a supply of zinc from a diversity of sources to supplement zinc imports, it is useful to assess the applicability of available separation technology. A brief review is presented of applications of several separation processes which have been applied to a variety of zinc waste dusts. In addition the results of bench scale tests are presented for a technically feasible scheme applied to a high zinc content fly ash from a waste to energy power plant which show a potential of providing a marketable zinc recovery product.

Recovery of zinc and some of its valuable salts from secondary resources and wastes

In Egypt, several kinds of recurring zinc-containing waste materials are available for metal zinc recovery. These include zinc scrap from spent dry cell batteries, zinc dross and zinc ash. These secondary resources were analyzed and their zinc contents determined. Pyrometallurgical and hydrometallurgical recovery processes for zinc and its salts were carried out. The factors affecting the performance and efficiency of the processes; such as particle size, temperature, concentration of acid leaching and time were studied. The results obtained revealed that zinc metal is successfully recovered from these secondary resources. The recovery efficiency amounts to 89% and 63% for zinc waste materials having a particle size diameter of + 1.25 mm and (− 0.4 + 0.315 mm), respectively. An optimum percentage of 10% weight of ammonium chloride fluxing agent was obtained. The optimum temperature for the recovery process was 600°C. With respect to the fine fraction of zinc dross, zinc ash and the slag left after pyrometallurgical treatment, acid leaching for extraction of the metal salts yields salts with a high efficiency (99%). The cost of recovery is acceptable on the basis of the low price of the materials input and energy consumption. Results were explained by an oxidation model and a salt refining mechanism.

Recycling of zinc waste for electrogalvanizing

An objective of Bureau of Mines recycling research is to devise technology that enables the recovery of metals, minerals, and other values from waste products and thus promote the wise and efficient use of our nation's resources. In line with this objective, Bureau researchers are investigating the use of waste products containing zinc as a source of zinc for electrogalvanizing. Industrial wastes used in this work were lead smelter flue dust, wastewater treatment sludge, copper smelter flue dust, and brass smelter flue dust. After zinc extraction with sulfuric acid, the resultant solutions were partially purified and used to electrogalvanize 0.234-cm (0.092-in.) diameter 1070 alloy steel wire, a common electrogalvanized product. The corrosion resistance of the electrogalvanized wire from waste electrolyte was compared with electrogalvanized wire from relatively pure electrolyte prepared in the laboratory, and electrogalvanized wire from an industrial electrogalvanizing plant. Corrosion rate measurements indicated that electrogalvanized wire obtained from waste electrolyte prepared from brass smelter flue dusts compared favorably with industrial electrogalvanized wire and electrogalvanized wire from the relatively pure electrolyte. The brass smelter flue dusts were chosen for more detailed studies. Impurities in the waste electrolyte caused some problems. Copper was undesirable because it passivated the soluble zinc anode. Other impurities such as cobalt and nickel were more tolerable but also slowly coated the anode. Owing to the ease of removal of copper by cementation, it posed no processing problem for electrogalvanizing. Successful completion of bench-scale work with brass smelter flue dusts led to large-scale trials at an industrial electrogalvanizing plant.

Recovery of Zinc from Zinc Ash and Flue Dusts by Hydrometallurgical Processing

A process has been developed for recovering zinc and other metal values from chloride-containing solid zinc waste materials such as zinc ash from galvanizing baths, and flue dusts from zinc smelting and Waelz processes. The waste is leached with a liquid organic phase containing a cation exchanger; the commercial carboxylic acid Versatic 911 is highly efficient for this operation. Halogens present in the organic phase are readily washed out with water. Zinc and other metal values are then selectively stripped with sulfuric acid, generating a neutral solution of zinc sulfate suitable for electrolytic production of zinc metal. Alternatively, zinc sulfate can be crystallized directly from the organic phase by stripping with concentrated sulfuric acid.