The development of a copper electrowinning plant with a capacity of 3000 tons per year in Zambia highlights the intricate balance of chemical and engineering principles required to efficiently produce high-purity cathode copper from mined oxide ores. This article provides an overview of the key components of the SX/EW process, focusing on the production scale, raw materials, process flow, metallurgical calculations, and equipment selection, with insights into technical and economic considerations.
Production Scale and Raw Material Characteristics
The plant is designed to process approximately 1670 tons of oxide ore per day, translating into an annual production of around 3141 tons of cathode copper. The ore, containing about 0.65% copper, requires precise handling to optimize copper recovery. Essential auxiliary materials, such as concentrated sulfuric acid and extractants like Lix984N, are critical for the solvent extraction and electrowinning process, enabling the production of high-purity copper cathodes.
| Element | Cu | Co | Pb | Zn | TFe | S | SiO₂ | CaO | Mg | Al |
|---|---|---|---|---|---|---|---|---|---|---|
| % | 0.65 | 0.01 | 10 | 1.4 | 1.5 | 2 |
Table: Oxide mineral composition
Process Flow and Key Operations
The SX/EW process starts with the leaching of copper from the ore using a single-stage stirring leaching process. This method is selected for its efficiency in both copper recovery and cost management. Post-leaching, the slurry undergoes thickening, with overflow directed to a high-copper filtrate tank and the underflow to a countercurrent decantation (CCD) washing process.
The extraction phase is crucial, where copper is selectively removed from the leachate using the solvent extraction method. The loaded organic phase undergoes washing to remove impurities like iron, followed by electrowinning, where copper is recovered as high-purity cathodes. The electrowinning cells operate by passing an electric current through the copper-rich solution, causing pure copper to deposit onto stainless steel cathode plates. The efficiency of this plant depends on factors such as the pH of the leaching solution, the sulfuric acid concentration, and the flow rates in the extraction stages.
Fig 1.1 copper electrowinning process flow chart
Metallurgical Calculations and Process Balances
Metallurgical calculations are critical for the SX/EW plant’s efficient operation. These involve balancing key elements like copper, cobalt, iron, magnesium, and aluminum. For example, the copper balance ensures nearly 88% copper recovery through high-efficiency electrowinning, with minimal losses. These balances ensure that the process is both efficient and environmentally responsible.
Water and sulfuric acid balances are also meticulously calculated. The water balance ensures optimal use of process water, while the sulfuric acid balance is crucial for maintaining the leaching efficiency and managing acid consumption.
Equipment Selection and Technical Considerations
Equipment selection is guided by the need for reliability, ease of maintenance, and energy efficiency. The leaching tanks, CCD thickeners, and electrowinning cells are selected based on specific process requirements, focusing on optimizing performance while minimizing operational risks. For instance, the leaching stirring tanks are designed to handle the specific slurry volume, ensuring adequate leaching time and copper recovery. Similarly, the CCD thickeners are chosen for effective countercurrent washing, ensuring the purity of the copper-rich solution entering the electrowinning phase.
Fig 1.2 Copper Plant Structure View
Economic and Technical Indicators
The success of this copper electrowinning plant is measured by a combination of technical and economic indicators. Key metrics include the copper leaching rate, washing efficiency, extraction and stripping efficiency, and overall plant throughput. The process aims to achieve a copper leaching rate of over 94%, with washing efficiency close to 94%, ensuring maximum recovery of copper with minimal environmental impact. The economic indicators also consider raw material costs, energy consumption, and equipment efficiency, contributing to the overall project’s viability.
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The design and operation of this copper SX/EW plant demonstrate the intricate balance between chemical engineering principles and practical considerations. From the selection of raw materials and process design to equipment selection and metallurgical calculations, every aspect of the plant is optimized to ensure high efficiency, low operational costs, and minimal environmental impact. This approach not only guarantees the production of high-purity cathode copper but also supports the sustainable development of the mining industry, particularly in regions like Zambia, where such plants are vital.
At Precision Technology, we specialize in crafting tailored proposals for copper plants, ensuring that every step, from concept to commissioning, aligns with your specific needs. Our expertise in SX/EW processes and equipment selection helps clients achieve optimal results, making us a trusted partner for your copper production projects. Contact us for free proposal of your plant!
