Hydrometallurgical Recycling of Copper Anode Furnace Dust for a Complete Recovery of Metal Values

Copper anode furnace dust is waste by-product of secondary copper production containing zinc, lead, copper, tin, iron and many other elements. Hydrometallurgical Copper Anode Furnace dust recycling method was studied theoretically by thermodynamic calculations and the proposed method was verified experimentally on a laboratory scale. The optimum condition for leaching of zinc from dust was identified to be an ambient leaching temperature, a liquid/solid ratio of 10 and H2SO4 concentration of 1 mol/L. A maximum of 98.85% of zinc was leached under the optimum experimental conditions. In the leaching step, 99.7% of lead in the form of insoluble PbSO4 was separated from the other leached metals. Solution refining was done by combination of pH adjustment and zinc powder cementation. Tin was precipitated from solution by pH adjustment to 3. Iron was precipitated out of solution after pH adjustment to 4 with efficiency 98.54%. Copper was selectively cemented out of solution (99.96%) by zinc powder. Zinc was precipitated out of solution by addition of Na2CO3 with efficiency of 97.31%. ZnO as final product was obtained by calcination of zinc carbonates.

Hydrometallurgical Treatment of Converter Dust from Secondary Copper Production: A Study of the Lead Cementation from Acetate Solution

The subject of interest in this study was lead cementation with zinc from solution after conventional agitate acidic leaching of converter dust from secondary copper production. The kinetics of lead cementation from an acid solution of lead acetate using zinc powder was studied. The optimal cementation conditions for removing lead from the solution were determined to have a stirring intensity of 300 rpm, a zinc particle size distribution <0.125–0.4> mm and an ambient temperature. Under these conditions, an almost 90% efficiency in removing lead from solution was achieved. The cementation precipitate contains Pb, and a certain amount of Cu. Lead is present in the cementation precipitate in the PbO, Pb5O8 and Pb(Cu2O2) phases. The solution after cementation was also refined from copper. The solution can be used for further processing in order to obtain a marketable Zn-based product. The resulting cementation precipitate can be further processed and modified to obtain a lead-based product. A kinetic study of the process of lead cementation from solution was also carried out. Based on experimental measurements, the value of apparent activation energy (Ea) which was found to be ~18.66 kJ·mol−1, indicates that this process is diffusion controlled in the temperature range 293–333 K.

Enhanced Micro-Electric Discharge Machining-Induced Surface Modification on Biomedical Ti-6Al-4V alloy

In the midst of a huge demand for high-precision miniaturized medical implants made up of potential biomaterials, the biomedical Ti-6Al-4V alloy meets the uncompromising standards for longevity, biocompatibility, and sterilizability required to interact with living cells in medical settings. This research tailored the existing capabilities of a traditional micro-electric discharge machining (μ-EDM) setup by adding 0, 2, 4, 6, 8, and 10 g/l bioactive zinc powder-particle-concentrations (PPCs) to the dielectric. A copper and brass micro-tool electrode (C-μ-TE and B-μ-TE) were employed in association with each PPC, and experiments were executed using one-variable-at-a-time (OVAT) approach. Machining time and dimensional deviation were chosen as the response variables of Zn powder mixed-micro-EDM (Zn-PM-μ-EDM). According to the analytical findings, the combination of C-μ-TE and 6 g/l Zn PPC achieved 23.52 %, 3.29 %, and 17.96 % lesser machining time, dimensional deviation, and recast layer thickness, respectively, compared to the B-μ-TE. The detailed study of this surface endorsed a significant modification in terms of improved recast layer thickness (26.44 μm), topography (Ra = 743.65 nm), and wettability (contact angle &lt; 90°), suggesting its dental application. Additionally, the observation of ZnO and TiO in X-ray diffraction and appealing in vitro cytocompatibility encourage the subsequent biological and therapeutic studies to validate the anticipated anti-viral activity of the modified Ti-6Al-4V alloy surface against coronavirus (COVID-19).

Heterogeneous Hydrogenation of Quinoline Derivatives Effected by a Granular Cobalt Catalyst

We communicate a convenient method for the pressure hydrogenation of quinolines in aqueous solution using a particulate Co-based catalyst that is prepared in-situ from simple Co(OAc)2 · 4 H2O through reduction with abundant zinc powder. This catalytic protocol permits a brisk and atom-efficient access to a variety of 1,2,3,4-tetrahydroquinolines thereby relying solely on easy-to-handle reagents that are all readily obtained from commercial sources. Both the reaction set-up assembly and the autoclave charging procedure are conducted on the bench outside an inert-gas-operated containment system thus rendering the overall synthesis time-saving and operationally very simple.

Optimization of Process Parameters and Kinetics Analysis of Cd Removal in ZnSO4 Production

In order to optimize the process parameters of Cd removal in the ZnSO4 production process and study the mechanism of Cd removal reaction, the response surface methodology was used to arrange Cd removal experiments and analyze the optimal production conditions, and the mechanism of Cd removal was studied using kinetics. The results show that the optimal process conditions for Cd removal are as follows: reaction temperature 55 °C, reaction time 13.43 min, and the zinc powder dosage should be 2.14 times that of Cd; the main effects of the three variables from large to small are zinc powder dosage, reaction temperature and reaction time; Cd removal is a second-order reaction, and the activation energy of the reaction is 29.6986 kJ/mol, so the reaction conforms to the diffusion control mechanism.

Analysis of methods for obtaining zinc-containing coatings using hot-dip galvanizing production waste

The article presents the waste generated during the production of hot-dip galvanizing. The analysis of the proposed methods of using these wastes in the production of zinc-containing coatings is carried out. It is shown that hard zinc can be successfully used in the compositions of saturating mixtures during thermal diffusion galvanizing of steel products and obtain high-quality coatings. The disadvantages include the need for grinding hard zinc.The dispersed waste of hot-dip galvanizing production, which is formed as a result of blowing pipes with superheated steam, can be used as a cheap substitute for expensive zinc powder in the compositions of zinc-filled paints. For paints, a fraction of 2–15 microns is used, which is 27 % of the total fractional composition. Therefore, in order to use a wider range of values of the fractional composition of dispersed waste to obtain zinc coatings and thus ensure the recycling of zinc into industrial circulation, the authors of this article plan to optimize and develop the compositions of powder compositions and the technology of thermal diffusion saturation of steel products based on zinc-containing waste.

Graphite Foil Waste to Graphene: New Carbon Precursors for Synthesis of Graphene and its Oxides

In this paper, graphene oxide (GO) was obtained by oxidation of powdered graphite foil wastes (pGFW) at 0 - 40°C. Oxidizing reagents can easily penetrate the layers of graphite foil and thus, the intercalation or functionalization-oxidation processes may occur resulting in graphite oxide formation. The methods of synthesis of GO and its separation from the reaction mixture were partially corrected. GO was reduced, also, to the reduced graphene oxide (rGO) by using hydroiodic acid, ascorbic acid, zinc powder, hydrazine, and Alnus extract. Thermal treatment of GO powders and GO films, obtained from pGFW was implemented at 20-300° C in air and at 20-1000° C under argon flow and in a vacuum. At high-temperature treatment (1000°C) of GO graphene was obtained with a defective structure.

Umbilical cord and umbilical care

In most human societies, ritualized and firm rules evolved for cutting the navel-string and handling the umbilical stump. These customs were not always beneficial, and contributed to umbilical infection, neonatal tetanus, and navel hernia. After prematurity, neonatal tetanus was the most frequent cause of death in poor countries up to the 19th century. It was caused by poor cord hygiene and by the age-old habit of severing the navel-string with biological products instead of man-made tools, which included palm leaves, blades of grass, mussel shells, crusts of bread, and other devices likely to be contaminated with tetanus spores. The navel-stump was covered with zinc powder, starch, oak-gall powder, grease, musk, clarified butter, and many other substances believed to protect the baby from evil, but actually creating anaerobic conditions in the umbilical wound. Care of the cord was associated with deep-rooted rituals and customs, and dangerous techniques persisted on islands well into modern times.

Disregulatory shifts in the red blood system during prolonged intoxication with copperzinc-pyrite ore (experimental study)

Introduction. Heavy metal compounds of copper-zinc pyrite ores can negatively affect the blood-forming and composition of peripheral blood of workers at mining and milling industry. Studying of the mechanisms of the development of metal-induced anemia will help in the search of ways to correct disorders in the red blood system. The study aims to estimate the mechanism of functional disorders of the central and peripheral parts of erythron in the long-term intoxication of natural heavy metal compounds in the experiment. Material and methods. The work was carried out on 50 white non-linear male rats weighing 220,5±15,5 g. Sample of the studied ore was provided by Uchalinsky Mining and Refining Plant (Uchaly, Bashkortostan Republic, Russia). The rats were given a water suspension of copper-zinc powder daily for 90 days for 1 hour before feeding, the dose was calculated on the basis of the maximum allowable concentration of lead (0,2-0,5 mg/kg) and cadmium (0,02-0,1 mg/kg) in grain and bread. The number of red blood cells, reticulocytes, hemoglobin and the concentration of erythropoietin were determined in the peripheral blood. Bone marrow erythropoiesis was evaluated by the quantitative and qualitative composition of erythroblastic islets (EI) and indicators of proliferation and maturation of erythroblasts in the EI. Statistical analysis was conducted using Mann-Whitney's non-parametric methods and Pearson's paired correlation. Results. On the 10th day young EI completely disappeared in the bone marrow, and erythropoiesis was supported only by reconstruction. In the peripheral blood the number of erythropoietin decreased by 22%, the number of reticulocytes doubled. The number of mature EI in the bone marrow was doubled by 30 days. By 90 days the number of reticulocytes in the blood returned to normal, but in the bone marrow the content of young forms of EI was 5 times less than the control values. Correlational analysis showed the absence of direct links between the central and peripheral parts of erythron in animals with chronic intoxication of copper-zinc pyrite ore, that present in the control group. Conclusion. With long-term combined exposure with heavy metals of natural origin, regulatory processes in the red blood system are disrupted, that is accompanied with inhibition of erythropoiesis in the EI.