A permanent insulator system for hydrometallurgy with a significant increase in electric efficiency and without short circuit

A permanent insulator system for hydrometallurgy has been developed with a significant increase in electric efficiency and without short circuits. The system consists of a double electric contact point for each cathode and anode and a new design of the insulating and contact system of the electrodes. The combination of these technologies provides a more uniform electric density inside each cathode and anode, in each cell, and also for the whole electric circuit in the cellhouse. Keeping a consistent maximum performance necessitates using parts with extreme durability against chemical attacks and short circuits. Hence, a comprehensive research into chemical stoichiometry and the behaviour of different molecules resulted in the development of an outstanding chemical resistance level to sulfuric acid and extremely high temperatures throughout the entire hydrometallurgical process. Field observations show that this formulation has been able to resist up to 19 years of continuous operation without maintenance. The goal of these developments combined with a new contact system was to reduce any type of short circuit by 70 to 80%, which in turn increases the electric current effectiveness by 8 to 10%. As a result, higher contact efficiencies have doubled the lifetime of the cathode and anode with this system. Consequently, the overall electric efficiency in a refinery cellhouse can be improved by 10-12%. Observations from real-world applications over the past decades have proven the efficiency of the earlier versions of this new concept. The system was found to be applicable to any type of contact system and has been used in various hydrometallurgical processes with great success. With the increasing price of energy and CO2 production, it has become more important to operate ecologically and efficiently to maximize profitability and this permanent insulator system can address many challenges which lead to a more efficient and cost-effective process.


Introduction
The widespread use of copper stems from its exceptional conductivity, corrosion resistance, and versatility.As the backbone of modern infrastructure, copper has witnessed an exponential surge in demand.In 2022 alone, global copper consumption surpassed 24 million metric tons, reinforcing its position as a critical resource for industrial development.With global demand for copper reaching unprecedented levels, major producers like Chile, Peru, and China face significant challenges in meeting the market needs, leading to price fluctuations.To enhance efficiency and reduce production costs in copper refineries, continual exploration of innovative solutions becomes imperative.Such

Fig. 1. Damages observed in the electrolytic cells in refineries
Failure to adequately maintain or replace insulators when necessary can lead to operational issues, including uneven current distribution and difficulty in maintaining optimal operating conditions within the cells.These issues ultimately reduce efficiency and production rates.Moreover, the maintenance and replacement demands of traditional insulators can result in production losses and potential shutdowns of the cellhouse, exacerbating the impact on efficiency [6].
In light of these challenges, a comprehensive examination of maintenance practices and potential solutions is essential for optimizing hydrometallurgy refining operations.This paper explores innovative approaches to improve the lifespan and performance of insulators, aiming to minimize maintenance requirements, enhance production efficiency, and reduce associated costs.

Design and build of equipotential insulators
Traditional insulator technologies often employ substandard or non-premium materials, and due to their multiple-piece design concepts, installation procedures are unnecessarily complex and time consuming, leading to operational challenges for the cellhouse.These issues include uneven current distribution and difficulties in maintaining optimal operating conditions.Consequently, efficiency is compromised, resulting in lower production rates.
Recognizing the critical role of insulators in establishing electrical connectivity and achieving consistent potential across all cells, a new generation of insulators, termed Permanent Equipotential Insulators, has been developed.These insulators exhibit exceptional durability and chemical resistance, making them suitable for the demanding conditions found in cell houses.The implementation of high-quality equipotential insulators can profoundly impact the efficiency of hydrometallurgy cell houses.
These advanced insulators ensure that cells operate at optimal voltage and current levels, thereby improving the overall process efficiency.Furthermore, utilizing pioneer technologies of manufacturing and material engineering, their superior resistance to wear and tear is extremely higher than other products in the industry.Such an extraordinary performance extends the lifespan of the cells,

Parametric Study
In order to evaluate the effectiveness and benefits of Equipotential insulators, a comprehensive parametric study was conducted, comparing them to traditional insulators.The study was based on a multi-criteria decision analysis (MCDA) with weighted benefits and costs and was focused on seven key aspects: enhanced cell protection, cost efficiency enhancement, reduced level or elimination of copper contamination, superior metal refining quality and purity, heightened safety measures, ecologic advantages and carbon footprint, and return on investment.The findings of this study provide insights into the significant advantages offered by Equipotential insulators and their potential to revolutionize the industry.

Enhanced Cell Protection
Equipotential insulators exhibited superior capabilities in safeguarding electrolytic cells.The study showcased their ability to mitigate some common issues that used to cause severe damage to the cells, reducing the risk of cell damage and facilitating optimal cell performance and longevity.These insulators are available in various shapes and designs, offering diverse functionalities.One such design incorporates side flanges, commonly referred to as the umbrella shape, which allows for a secure fit over two adjacent cells.The design features a dedicated slot for positioning the contact bar and serves as a protective shield against thermal chocks resulting from short circuits and chemical corrosion (Fig. 3).In the event of a short circuit, the insulator acts as a barrier, preventing the heat flow created by the electric current from reaching the electrolytic cells.This safeguards the cells from the detrimental effects of excessive heat, thermal impacts and mechanical stress associated with short circuits.
During a short circuit, the normal path of electric current is diverted, resulting in the generation of excessive heat that quickly raises the temperature of the insulator.This rapid temperature rise induces mechanical stress and other forms of damage.Additionally, the excessive heat generated by a short circuit can adversely affect the electrolytic cells positioned beneath the insulator.These cells are designed to operate within specific temperature limits, and exposure to excessive heat can diminish their efficiency or lead to complete failure.Furthermore, certain equipotential insulators are specifically designed to combat chemical corrosion.They feature a protective coating that resists the corrosive effects of acid spills commonly encountered in electro-refineries.In the event of an acid spill, the permanent insulator acts as a shield, redirecting the acid away from the electrolytic cells, thus preserving their integrity and preventing damage.

Cost Efficiency Enhancement
The study revealed a notable reduction in electrical costs with the implementation of Permanent Equipotential insulators.Compared to traditional insulators, these advanced counterparts demonstrated improved electrical efficiency, resulting in substantial cost savings for the refining process.This can be attributed to significant influence of the alignment and tolerances of electrode seats on the performance of a refinery cell house.However, achieving precise alignment poses challenges when using traditional multi-piece insulators.
The choice of insulator design traditionally depends on factors such as cell size, shape, available space, and other specific electrorefining requirements.In contrast, permanent equipotential insulators are manufactured in a single piece form, reinforced with pultruded fiberglass bars, with a highly adaptive design.These insulators are produced using a unique process that ensures a homogeneous, continuous-length structure with exceptional dimensional stability.
With precision reaching up to 0.5 mm centre-to-centre and 2.8 mm along an 11-meter length from the first to the last anode, they offer a secure fit and accurate positioning for electrodes, minimizing vulnerability to mechanical stress and other damage.The permanent insulator, consisting of a single monolithic piece, incorporates various components such as contact bars, anodes, and cathode seats insulation.The insulating seats are meticulously arranged and are perfectly synchronized with the contact bar positioned at the centre of the permanent insulator.This synchronization is achieved by utilizing the embedded longitudinal pultruded fiberglass rebars, which seamlessly integrate with the equipotential insulator.The contact system is securely anchored, rendering any relative movement impossible.The precision of this contact system is maximized, ensuring its longevity throughout the entire lifespan of the structure.As a result, the lifespan of these insulators is extended, reducing the likelihood of electrical failures caused by misaligned electrodes, such as short circuits and uneven electroplating.

Reduced Level or Elimination of Copper Contamination into Pure Cathodic Zinc
During the daily zinc harvesting process, an abrasion occurs between the contact bar and the aluminium cathode copper contact, leading to the generation of fine powder.This powder subsequently falls into the cell and plates onto the cathode, causing a significant impurity issue.To address this challenge, certain types of equipotential insulators are designed with a unique builtin solution.Specifically, equipotential permanent insulators are designed with an integrated copper powder dust collector that features two slopes, facilitating the evacuation of the copper powder when the insulator is washed.Consequently, the expelled copper powder can easily be recovered and eliminated using an appropriate system.

Superior Metal Refining Quality and Purity
The implementation of Permanent Equipotential insulators resulted in elevated standards of metal refining.The study demonstrated that these insulators contribute to higher quality and purity of the refined metal products, enabling producers to meet stringent industry requirements and enhance their market competitiveness.
Inconsistent electrical distribution in a cellhouse can negatively impact the quality and purity of extracted copper.Uneven copper deposition on cathode plates, imbalanced dissolution rates of anodes, and disrupted electrolyte boundary layers are some factors contributing to this issue.Maintaining a consistent electrical distribution is crucial to avoid variations in copper coating thickness, impurity incorporation, and inefficient refining conditions.By addressing these challenges, refineries can optimize their processes and achieve high-quality copper extraction.
Permanent equipotential insulators act as a protection against electrical disturbances, such as short circuits, by providing superior electrical insulation.This maintains a consistent electro-refining process, minimizing the occurrence of irregularities and impurities in the copper plating.The result is plating with a higher-quality end products that achieves improved market value.

Heightened Safety Measures
One of the significant findings of the study was the enhanced safety provided by Equipotential insulators.These insulators effectively minimize the potential for accidents and operational hazards, ensuring a safer working environment within the cellhouse.
The improved safety measures for the working environment in hazardous settings like zinc electrorefineries can be attributed to the fact that the continuous and consistent level of insulation that permanent equipotential insulators provide plays a vital role, specially at 200,000 Ampere with 900 Ampere/m 2 .These insulators effectively mitigate the risk of electrical accidents and injuries that can occur in such environments (Fig. 6).In the absence of proper insulation, electrical leaks, operators are susceptible to electrical shocks arising from potential differences between different parts of the electrical system.However, by functioning as intended, insulators prevent electric current from flowing through a person's body if accidental contact with the system occurs, effectively eliminating the chances of serious injury.The reliable insulation provided by permanent equipotential insulators was found to enhance the overall safety of the refinery, safeguarding workers from potential electrical hazards and ensuring a secure operational environment.Fig. 6.High separating walls help with eliminating short circuits and electrical leakage between adjacent electrodes, and cell to cell.

Ecologic Advantages and Carbon Footprint
Permanent equipotential insulators offer not only numerous operational advantages but also contribute to ecological benefits by reducing CO2 emissions and minimizing carbon footprint.The implementation of these insulators in copper electro-refineries results in a more efficient electrorefining process, which in turn reduces energy usage and increases productivity.By improving electrical efficiency and preventing irregularities in the refining process, permanent equipotential insulators help optimize the overall performance of the refinery.This enhanced efficiency leads to reduced energy consumption, thereby lowering CO2 emissions associated with energy production.Additionally, the improved quality and purity of the extracted copper achieved with equipotential insulators reduce the need for additional refining steps, minimizing carbon-intensive processes and reducing the carbon footprint of the entire refining operation.Therefore, the adoption of permanent equipotential insulators not only offers operational benefits but also contributes to a more sustainable and environmentally friendly approach to copper electrorefining.

Return on Investment
Permanent equipotential insulators offer a multitude of advantages that make them a valuable investment for refineries.It is true that these insulators are made of premium materials, and hence, there is a premium upfront cost for them.However, despite their initial cost compared to traditional insulators, their exceptional longevity and durability result in a reduced need for frequent replacements, leading to substantial cost savings over the long term.
By minimizing the frequency of insulator replacements, refineries can significantly reduce maintenance expenses and operational downtime, optimizing their overall cost-effectiveness.Most traditional insulators need replacement over a life of two years or less, compared to field observations that have shown equipotential insulators are able to operate continuously for up to 20 years without requiring maintenance.The cost of replacing traditional insulators includes not only the material cost but also labour, downtime, and potential operational disruptions.This can result in a potential cost saving of up to 70% on the insulators over a 20-year period.
Moreover, these insulators play a pivotal role in enhancing the efficiency and effectiveness of the electrorefining process.Their consistent maintenance of electrical potential ensures a stable and reliable electrical distribution, minimizing the occurrence of voltage fluctuations, short circuits, and uneven electroplating.This improved operational efficiency translates into increased productivity, reduced wastage, and improved product quality, contributing to higher profits for the refinery.
Considering a reduction of 70 to 80% in the number of short circuits by using the equipotential insulators, an 8 to 10% increase in electric current efficiency will be achieved, thanks to their small dimensional tolerances of less than 2.5mm in insulators with up to 10.5m and being single-piece instead of multi-piece.This will be combined with better protection and extended lifespan of the electrodes themselves up to 3 times (12 years instead of 4 years), and the lifespan of the cell up to two times.Moreover, the higher mechanical and thermal resistance of these insulators lets the operation to go under higher current intensity.Hence, it was estimated to result in up to 12% less electricity consumption per ton of copper in the cost of operation.
The initial investment in premium raw materials for equipotential insulators can be offset by the long-term cost savings from reduced replacements and the enhanced productivity achieved through their consistent electrical performance.As a result, refineries can experience major favourable financial outcome and a higher return on investment (ROI) by choosing permanent equipotential insulators.This combination of long-term cost savings, improved operational efficiency, and higher productivity makes equipotential insulators a compelling choice for refineries seeking to maximize profitability and achieve sustainable growth in the electrorefining industry.

Conclusion
In conclusion, the comprehensive research conducted on permanent equipotential insulators and their chemical formulation has yielded remarkable results.These insulators demonstrate exceptional mechanical, chemical and thermal resistance with permanent physical consistency, withstanding the corrosive effects of sulfuric acid and extreme temperatures throughout the hydrometallurgical process.
The primary objective of these developments, along with the implementation of a new contact system, was to significantly reduce the occurrence of short circuits.As a result, the extended lifespan of the cathode and anode has effectively doubled, leading to improved overall electric efficiency in refinery cellhouses.
Real-world applications have demonstrated the efficiency of earlier versions of this concept, proving its applicability in various hydrometallurgical processes.Given the rising energy costs and concerns about CO2 production, the utilization of these permanent insulators offers an ecological and efficient approach to maximize profitability.
Lastly, while they may initially involve a higher investment due to their premium materials, their durability and longevity translate into fewer replacements and long-term cost savings.These advantages, coupled with the improved efficiency and consistency they provide to the electrorefining process, contribute to a higher return on investment.Therefore, permanent equipotential insulators represent a wise investment choice for refineries, offering both financial and operational benefits.

Fig. 4 .
Fig. 4. Coronary insulator combined with permanent Equipotential insulator protecting two adjacent cell walls from thermal, mechanical and chemical stresses.

5 .
(a) Without Coronary Insulator (b) With Coronary Insulator Fig. Thermal test on the performance of coronary equipotential insulator when subjected to intense thermal load due to a short circuit