Modelling the Effect of Solution Composition and Temperature on the Conductivity of Zinc Electrowinning Electrolytes

Zinc electrowinning is an energy-intensive step of hydrometallurgical zinc production in which ohmic drop contributes the second highest overpotential in the process. As the ohmic drop is a result of electrolyte conductivity, three conductivity models (Aalto-I, Aalto-II and Aalto-III) were formulated in this study based on the synthetic industrial electrolyte conditions of Zn (50–70 g/dm3), H2SO4 (150–200 g/dm3), Mn (0–8 g/dm3), Mg (0–4 g/dm3), and temperature, T (30–40 °C). These studies indicate that electrolyte conductivity increases with temperature and H2SO4 concentration, whereas metal ions have negative effects on conductivity. In addition, the interaction effects of temperature and the concentrations of metal ions on solution conductivity were tested by comparing the performance of the linear model (Aalto-I) and interrelated models (Aalto-II and Aalto-III) to determine their significance in the electrowinning process. Statistical analysis shows that Aalto-I has the highest accuracy of all the models developed and investigated in this study. From the industrial validation, Aalto-I also demonstrates a high level of correlation in comparison to the other models presented in this study. Further comparison of model Aalto-I with the existing published models from previous studies shows that model Aalto-I substantially improves the accuracy of the zinc conductivity empirical model.

Investigation on the Electrochemical Deposition of Nanocrystalline Zinc with Cationic Polyacrylamide (CPAM)-ZnSO4 Electrolyte

The electrochemical deposition of nanocrystalline zinc has high potential to deposit zinc coatings, which have improved wear and corrosion properties compared to conventional coating methods. Conventionally, two or more additives are used in the electrolyte for the formation nanocrystalline zinc; these electrolyte components are complex, and their maintenance is inconvenient, making it unstable and not suitable for industrial scale production. This paper proposes an electrochemical deposition technique for nanocrystalline zinc using a ZnSO4 solution with cationic polyacrylamide (CPAM) as the unique additive. The results reveal that the cationic degree of CPAM has a significant influence on the deposition process and that the cationic degree of 20% enhances the electrolyte conductivity and improves the density of the deposited coating. The concentration of CPAM affects the electrolyte viscosity and conductivity. CPAM with a concentration of 20 g/L could simultaneously improve the electrolyte conductivity and maintain the viscosity at a low value, which promotes the formation of a bright deposited coating with a grain size of 87 nm. Additionally, the current density affects the grain structure of the deposited coating. With a current density of 0.5 A/dm2, a dense coating with lamellar grains and a grain size of 54.5 nm was obtained, which has, and the surface roughness was reduced to 0.162 μm. Moreover, the corrosion resistant property of the deposited coating was also improved.

Research on Multiphysics Coupling Fields in Electrochemical Trepanning of Lateral Flow

Electrochemical trepanning (ECTr) is an effective method for machining the ruled surface parts. Generally, the forward flow mode is used in ECTr. Under the forward flow, the streamlines at the outlet are divergent, resulting in the obvious flow patterns at the outlet and the instability of the machining process. In ECTr of a diffuser with a special structure, the lateral flow mode is adopted to improve the uniformity of the flow field, thereby improving the surface quality at the hub. ECTr is a complicated multiphysics coupling process. To investigate the distributions of electric field, two-phase flow field and thermal field in ECTr with lateral flow, a multiphysics coupling field model was established. In this model, a coupling relationship was formed between the various physical fields through the change of the electrolyte conductivity. Through the multiphysics coupling simulation, the changes of the gas bubbles volume fraction, the electrolyte temperature, the electrolyte conductivity and the current density were obtained along the flow path. Compared with the inlet of the electrolyte, the gas bubbles volume fraction and the temperature at the outlet increased by 38.8% and 6.3 K, respectively. Under the combined influence, the conductivity decreased by 7.227 S/m at the outlet, resulting in a decrease of 57.81 A/cm2 in the current density. Then, the corresponding experiment of lateral flow ECTr was performed to verify the simulation results. Along the flow path, the thickness of the machined blade gradually increased, varying from 2.09 mm to 2.76 mm. The surface quality gradually deteriorated along the flow path and the surface roughness varied from Ra 0.72 μm to Ra 1.05 μm. Combining the simulation and the experiment, the correctness and the effectiveness of the multiphysics coupling model and simulation were confirmed. The results can be applied to other ECM processes.

Improving High Rate Cycling Limitations of Thick Sintered Battery Electrodes by Mitigating Molecular Transport Limitations through Modifying Electrode Microstructure and Electrolyte Conductivity

For batteries, thicker electrodes increase energy density, however, molecular transport limits the rate of charge/discharge for extracting large fractions of available energy. Mitigating transport limitations by increasing electrolyte conductivity and...

Soil Improvement & Conservation Based on Biosoildam Integrated Smart Ecofarming Technology (Applied in Java Alluvial Land & Arid Region in East Indonesia)

Biosoildam a technology that combines agricultural and environmental activities (water & soil conservation) based on IOT. This analysis aims to improve alluvial agricultural lands by analyzing the relationship between microbial activity on acidity and the infiltration rate for alluvial lands that widely spread on the north coast of Java with Biosoildam Technology. Microbial activity as a biological agent / biofertilizer of slurry biomass decomposition taken from the livestock center and soil conditioning will affect soil electrolyte conductivity (EC). Other variables use the humidity and soil temperature parameters to control the relationship. Integrated Ecofarming where harvest straw for feed and livestock waste for fertilizer in micobial decomposting process is a cost-effective method that can improve soil quickly and measurably. The research took place from January to July 2018 on the red onion farms in Nganjuk Regency. The tools used include Double Ring Infiltrometer for measuring the infiltration rate at three radial distances from the centre of the microbial hole (biohole), microcontroller & wifi, electrolyte conductivity sensor as the soil fertility indication, pH meter for measuring soil acidity, and humidity and soil temperature sensors. The real-time information on soil paramaters is obtained through analogue inputs from EC, pH, humidity and temperature sensors, converted into digital information data by a microcontroller which later sent via wifi. Sensors are spreadly placed with radius A= 1,5 m ;B= 2 m ; C= 3m. Average Result : infiltration rate =40cm/h EC=1100 M=45 % T=25°C pH=6,5.