Abstract
Increasing silver production rate has been a challenge for the existing refining facilities. The application of high current density (HCD) as one of the possible solutions to increase the process throughput is also expected to reduce both energy consumption and process inventory. From the recently-developed models of silver electrorefining, this study simulated the optimum electrolyte parameters to optimize the specific energy consumption (SEC) and the silver inventory in the electrolyte for an HCD application. It was found that by using [Cu2+] in electrolyte, both objectives can be achieved. The suggested optimum composition range from this study was [Ag+] 100–150 g/dm3, [HNO3] 5 g/dm3, and [Cu2+] 50–75 g/dm3. HCD application (1000 A/m2) in these electrolyte conditions result in cell voltage of 2.7–3.2 V and SEC of 0.60–1.01 kWh/kg, with silver inventory in electrolyte of 26–39 kg silver for 100 kg per day basis. The corresponding figures for the conventional process were 1.5–2.8 V, 0.44–0.76 kWh/kg, and 15.54–194.25 kg, in respective order. These results show that, while HCD increases SEC by app. 30%, the improvement provides a significant smaller footprint as a result of a more compact of process. Thus, applying HCD in silver electrorefining offers the best solution in increasing production capacity and process efficiency.
Highlights
Silver is used in many applications such as coins, jewelry, medicine, dentistry, plating, electrical technology, chemical equipment, catalyst, and photography [1]
One of the developments was high current density (HCD), or the application of current density over 1000 A/m2 silver electrorefining, which offers a logical solution for the increasing capacity demand
This study simulates the impact of HCD, 1000 A/m2 current density operation in silver electrorefining through the optimization of the electrolyte composition
Summary
Silver is used in many applications such as coins, jewelry, medicine, dentistry, plating, electrical technology, chemical equipment, catalyst, and photography [1]. The evaluation of optimum parameters was designed mainly based on two calculated outcome of specific consumption (SEC). Theenergy evaluation of optimum parameters designed mainly based on two calculated outcome of specific energy consumption (SEC) and silver inventory in the process. Consumption electrical energy consumption (Econs ) outlined in Equation (1), the SEC of a silver electrorefining process. With the data of the constants (n, F the electrical energy consumption (Econs) outlined in Equation (1), the SEC of a silver electrorefining and M ) and the current efficiency of conventional process of 92–95% [9,11] and HCD of 98–99% [4], processAgis defined as Equation (2) below, where Ecell is the cell voltage (V). With the data of the the only variable left from Equation (2) is the cell voltage (Vcell )
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