Nodule Formation on Copper Electrodeposits in the Rotating Cylinder Hull Cell

Nodulation formation during the electrolytic production of high-purity copper can lead to impurity entrapment and/or increased energy consumption. The rotating cylinder Hull cell (RCHC) was used to study copper nodule formation under mass transport conditions similar to industrial electrolytic copper production. The main advantage of the RCHC is that a wide range of current densities can be produced in a single experiment with well-defined mass transfer conditions. Visible nodule formation was observed at current densities greater than 250 A/m2, which is an iavg/iL ratio of 0.30 for a simulated conventional electrowinning cell. Statistical analysis was also performed using the Weibull distribution to describe the increase in probability of nodule formation with the increase in current density. Introduction of a commercial electrowinning smoothing agent (Hydrostar 10) sharply decreased the total amount of nodulation, but did not eliminate it

Effects of Carrier, Leveller, and Booster Concentrations on Zinc Plating from Alkaline Zincate Baths

Organic additives are required for alkaline zincate plating baths to obtain an acceptable coating on steel for corrosion protection. The effects and possible interactions of three commercial additives (Eldiem Carrier, Eldiem Booster, and Bright Enhancer 2x on zinc electrodeposition from a high-concentration alkaline zincate bath were investigated. Visually acceptable deposits were produced within the current density range of 130 to 430 A m−2 for most additive conditions examined. Over concentration ranges examined, decreasing the booster concentration led to brighter zinc deposits, and an interaction between the carrier and the booster was detected. The additives fostered the formation of compact and adherent coatings as illustrated by scanning electron microscopy. Throwing power and current efficiency were not impacted by the additives over the concentration ranges examined. Linear sweep voltammetry proved that the additives increased the overpotential for zinc deposition. The additive combination that produced the brightest deposit also demonstrated the strongest adsorption of additives in linear sweep voltammetry

Chemical utilization of sequestered carbon dioxide as a booster of hydrogen economy

Journal ArticleFor many, hydrogen in a pure hydrogen economy would be like natural gas in today's energy economy. Unfortunately, hydrogen's physical properties are unsuited to the energy market's requirements in terms of packaging, storage, transfer, and delivery. In this paper, a hybrid energy economy that packages hydrogen chemically on carbon atoms from various sources including recycled carbon dioxide is introduced and discussed. For this new hybrid energy economy to become a sustainable reality, the ability to recycle carbon dioxide and use hydrogen to create an appropriate energy product, such as dimethyl ether (DME), is needed. DME is recognized as a potential next generation, "beyond-petroleum", environmentally benign commodity for energy storage and distribution. It is expected that to maximize the sustainability of the proposed hybrid energy economy, "green" hydrogen will be utilized. The "green" hydrogen would be created by the electrolysis of water powered by renewable energy sources, such as solar, wind or geothermal heat

The sustainability of European agricultural firms

There has been an undeniable and remarkable performance of the global food system over the last fifty years. During this period, total food supply has increased almost threefold, whereas population has only increase in a twofold ratio, along with very significant shifts in diet related to the economic development. European agricultural activity plays an important role in European and world food security through the agricultural production, supply and international trade. The main aim of this paper was analyses the agricultural sustainability of the twenty-eight Member States of the European Union in terms of economics, environmental, social and political activity. Information and data comes from FADN database from the European Commission related to the year 2013, because is the last information available. The methodology includes the min-max approach based on the four components of sustainability, namely, economic, social, environmental and politics. We include the new component of politics in the sustainability because European agricultural are high subsidised and these subsidies have impacts on European agricultural sustainability. All the referred components of sustainability were based on various indicators in each component based on the literature. The minmax approach was employed to normalise the selected indicators expressed in variety dimensions for their need to be put on a common basis. Multivariate methods, namely Component Principal Analysis was used to estimate weights for the selected indicators to construct sub-indices and then the subindices were aggregated into the farm relative sustainability index. After, cluster analysis was used to form homogeneous groups of European countries according the agricultural sustainability indices. The results confirm three groups of European countries, namely, the North and Central countries; the New Member States and the Mediterranean counties. The results confirm that European agriculture firms and respective countries had a medium sustainability. The results also confirm that Northern European countries and the New Member States (of Eastern Europe) presents the highest levels of economic and political sub-indices of sustainability, confirming the high level of support for EU agricultural policies. However, are the Mediterranean countries (Southern Europe) that presents the highest environmental sustainability sub-indices. The main conclusion highlines confirms the importance of the sustainability as a tool to better adjust agricultural policies among the European Member States and around the word in other sectorial firms, for better adjust sectorial policies.N/

Global Tellurium Supply Potential from Electrolytic Copper Refining

The transition towards renewable energy requires increasing quantities of nonfuel mineral commodities, including tellurium used in certain photovoltaics. While demand for tellurium may increase markedly, the potential to increase tellurium supply is not well-understood. In this analysis, we estimate the quantity of tellurium contained in anode slimes generated by electrolytic copper refining by country between 1986 and 2018, including uncertainties. For 2018, the results indicate that 1930 (1500-2700, 95% confidence interval) metric tons of tellurium were contained in anode slimes globally. This is nearly quadruple the reported tellurium production for that year. China has the greatest potential to increase tellurium supplies. However, most of the tellurium potentially recoverable by Chinese refineries appears to come from copper mined elsewhere. Further research into the business decisions associated with tellurium recovery may help translate the physical availability of tellurium into economic availability. The methodology presented here can be applied to other byproduct elements

Electrolytic Recovery of Bismuth and Copper as a Powder from Acidic Sulfate Effluents using an emew® Cell

Effective removal of bismuth is a primary concern during copper electrorefining. A novel electrowinning process using an emew® cell was developed to recover bismuth and copper from a copper electrorefining waste stream. Significant removal and co-deposition of copper and bismuth were achieved from a highly acidic sulfate industrial effluent using a current density of 350 A m-2, but the current efficiency was low (27%). Operating at a lower current density (75 A m-2) facilitated the preferred removal of Cu, while increasing current efficiency to 67.4% due to the decrease of aside-reaction. Consequently, a two-stage process was employed to remove most of the copper at low current and then extract bismuth at high current. 93.4% of the bismuth and 97.8% of the copper were recovered with a satisfactory current efficiency, and a high purity (~98%) Bi powder was obtained in the second step. This novel emew® cell approach may serve as a promising alternative for recovering copper and bismuth, and the proposed two step strategy may offer insight for the selective recovery of metals in a multi-component system

Removal of Sb Impurities in Copper Electrolyte and Evaluation of as and Fe Species in an Electrorefining Plant

Antimony and arsenic concentrations and their oxidation states (Sb(III), Sb(V), As(III) and As(V)) in copper electrorefining electrolyte can affect copper cathode quality through the formation of floating slimes. A laboratory-scale pilot plant was operated to remove Sb from commercial electrolyte. The pilot plant consisted of a pre-treatment process with copper shavings followed by ion exchange. The results indicated that Sb(III) was removed from copper electrolyte completely, while Sb(V) was partially eliminated. The concentrations of As(III) and As(V) were not affected, and the poisoning of the ion exchange resin by Fe(III) was avoided by pre-reduction to Fe(II) by copper shavings. The operation configuration of the pilot plant was applied to the design of an industrial plant for Sb/Bi removal at the Atlantic Copper Refinery in Huelva, Spain. The evolution of Sb, Fe and As species in the commercial electrolyte was monitored prior to and after the installation of the Sb/Bi removal plant. The results show a ca. 45% decrease in total Sb content (from 0.29 g L−1 to 0.16 g L−1) in the electrolyte. This reduction is more noticeable for Sb(III), whose concentration decreased from 0.18 g L−1 to 0.09 g L−1, whereas Sb(V) concentration diminished from 0.11 g L−1 to 0.07 g L−1. The resin also retained ca. 75% of the Bi content (0.15-0.22 g L−1). The total As increased during the study period (from 7.7 to 9.0 g L−1) due to changes in plant inputs. Arsenic was predominantly As(V) (ca. 93-95%). The total Fe concentration experienced little variation (0.9-1.1 g L−1) with Fe(II) being the main species (ca. 94-96%)

Removal of Sb Impurities in Copper Electrolyte and Evaluation of As and Fe Species in an Electrorefining Plant

Antimony and arsenic concentrations and their oxidation states (Sb(III), Sb(V), As(III) and As(V)) in copper electrorefining electrolyte can affect copper cathode quality through the formation of floating slimes. A laboratory-scale pilot plant was operated to remove Sb from commercial electrolyte. The pilot plant consisted of a pre-treatment process with copper shavings followed by ion exchange. The results indicated that Sb(III) was removed from copper electrolyte completely, while Sb(V) was partially eliminated. The concentrations of As(III) and As(V) were not affected, and the poisoning of the ion exchange resin by Fe(III) was avoided by pre-reduction to Fe(II) by copper shavings. The operation configuration of the pilot plant was applied to the design of an industrial plant for Sb/Bi removal at the Atlantic Copper Refinery in Huelva, Spain. The evolution of Sb, Fe and As species in the commercial electrolyte was monitored prior to and after the installation of the Sb/Bi removal plant. The results show a ca. 45% decrease in total Sb content (from 0.29 g L−1 to 0.16 g L−1) in the electrolyte. This reduction is more noticeable for Sb(III), whose concentration decreased from 0.18 g L−1 to 0.09 g L−1, whereas Sb(V) concentration diminished from 0.11 g L−1 to 0.07 g L−1. The resin also retained ca. 75% of the Bi content (0.15–0.22 g L−1). The total As increased during the study period (from 7.7 to 9.0 g L−1) due to changes in plant inputs. Arsenic was predominantly As(V) (ca. 93–95%). The total Fe concentration experienced little variation (0.9–1.1 g L−1) with Fe(II) being the main species (ca. 94–96%)

Characterization and Leaching Feasibility Studies of Copper Flue Dust for the Recovery of Main and Trace Metals

Although copper smelter dust (CSD) is classified as hazardous waste, it also serves as a valuable secondary resource, offering potential for the recovery of critical elements. In this study, CSD samples were collected from the waste heat boiler (WHB) and electrostatic precipitator (ESP) units connected to the flash smelting furnace at a copper smelter. The representative samples were extensively characterized by particle size, and chemical and mineralogical analyses. Following sample characterization, leaching experiments were performed to evaluate the potential extraction of Cu, Fe, As, Zn, Pb, In, Ga, and Ge from the flue dusts. Distilled water, H2SO4, and HCl were employed as lixiviants. The characterization results showed that 80% of the particles by weight in WHB and ESP samples were smaller than 104 μm and 46 μm, respectively. The WHB sample comprised 23.3% Cu, 20.3% Fe, 7.2% S, 1.8% As, and 1.5% Pb, whereas the ESP sample contained 21.2% Cu, 15.9% Fe, 1.8% As, and 1.5% Pb. The concentrations of Ga, Ge, and In were relatively low and nearly identical in both samples, measuring 6 ppm, 33 ppm, and 18 ppm, respectively. TIMA analysis indicated that the WHB and ESP samples were predominantly composed of CuFe sulfates (25–43 wt%), FeCu oxides (11–16 wt%), FeCu and CuFe silicates (13–28 wt%), and Cu sulfates (10–13 wt%). Additionally, Fe-Cu silicate phases served as the primary host for Ga, Ge, and In in both samples. The leaching efficiencies obtained in water for WHB sample were 43% for Cu, 35% for Zn, and 72% for Cd. In comparison, the ESP sample exhibited higher leaching efficiencies, with values of 62% for Cu, 50% for Zn, and 80% for Cd. Meanwhile, the leaching efficiencies for the rest of target elements in both samples were under 12%. Under high acid concentrations, the WHB and ESP samples demonstrated nearly complete extraction of Cu, As, Cd, and Fe at over 90%, while also achieving high leaching efficiencies for trace elements, with Ga at 75–82%, Ge at 84–86%, and In at 90–93%. Implementing a water pre-leaching stage reduced solid residue mass by 40–50% and yielded a pregnant leach solution enriched with 10,700–14,200 mg L⁻1 Cu, 101–180 mg L⁻1 Cd, and 193–294 mg L⁻1 Zn, facilitating simplified downstream purification for critical elements