Copper Mining and Processing: Processing Copper Ores
Copper Mining and Processing: Processing Copper Ores
View PDF Download PowerPoint
RE TECH provides reliable and professional services.
Copper processing involves a multifaceted process that starts with ore mining (which contains less than 1% copper) and culminates in the production of 99.99% pure copper sheets, known as cathodes, utilized in various everyday applications. Two principal types of ores are identified: copper oxide and copper sulfide. Their distinct mineralogical compositions necessitate different processing techniques—hydrometallurgy for copper oxides and pyrometallurgy for copper sulfides. Copper oxide ores tend to be more prevalent closer to the Earth's surface, albeit classified as low-grade due to their lower copper content. Consequently, while extraction and processing may require handling larger ore volumes, the overall expenses remain lower, making oxide mining profitable. In contrast, although copper sulfide ores are less common, they boast higher copper yields. Processing sulfides incurs greater expenses but results in larger quantities of copper recovery. Due to the distinctive characteristics of each mine's mineral content, mine planners must assess the most economical processing methods. When feasible, a mine may recover both types of copper; however, depending on economic factors, they may focus solely on either oxides or sulfides.
A. Processing of Oxide Ore
The processing of oxide ores typically involves hydrometallurgy, a method that employs water-based solutions to efficiently extract and purify copper from oxide ores at ambient temperatures. This process generally unfolds in three phases: heap leaching, solvent extraction, and electrowinning.
Heap leaching is employed to extract metals using percolating chemical solutions and is particularly effective for low-grade ores that are not economically viable for milling. After the crushing and transportation of the ore, it is formed into a heap atop an impermeable layer on a slight slope. Sprinklers distribute a leaching reagent, typically dilute sulfuric acid, atop the heap, which seeps through and dissolves the copper. This results in a 'pregnant' leach solution containing concentrations of sulfuric acid and copper sulfate ranging from 60% to 70%.
The second phase is solvent extraction, where two unmixable liquids are stirred together, allowing copper ions to migrate from the leach solution into the organic solvent. Following separation, copper remains dissolved in the solvent while impurities are filtered away, and the remaining leach solution is recycled for further processing.
Finally, the electrowinning phase involves passing an electric current through the copper solution, facilitating the deposition of copper ions onto a cathode (negative electrode) to yield 99.99% pure copper.
B. Processing of Sulfide Ore
In contrast, sulfide ores undergo pyrometallurgy, a thermal-based technique involving a series of physical processes, utilizing high temperatures to extract and purify copper, typically in four stages: froth flotation, thickening, smelting, and electrolysis.
Initially, the crushed ore is milled further to produce a slurry, a mixture of valuable minerals and non-valuable rock (gangue). The slurry is introduced into a tank, where froth flotation techniques are employed to isolate copper minerals from gangue. Chemical agents, known as 'collectors', are added to enhance the adherence of copper particles to air bubbles, which rise to the surface to form an enriched froth that is skimmed for additional processing. Residual gangue settles at the bottom for disposal as mine tailings.
Subsequently, the froth proceeds to a thickening phase in large tanks where bubbles dissipate and solids settle out, creating a concentrated copper solution. This mixture, comprising approximately 30% copper and other metals, is forwarded to the smelting facility.
Renowned as a premier supplier for copper melting plant solutions, we ensure that our experts assist you in meeting all your copper processing needs.
In the smelting process, concentrated ores undergo heating in furnaces at temperatures exceeding 2,300 °F, transitioning into a molten state. This molten copper interacts with silica to produce a glassy slag and a copper matte, containing roughly 58-60% copper. Additional refining in converters results in 'blister copper', with a 98% copper concentration.
The final electrolysis step crystallizes the copper anode slabs hung in an electrolyte-rich solution, facilitating the transfer of copper ions onto cathodes. This results in cathodes weighing approximately 375 pounds, incorporating 99.99% pure copper and can be indistinguishably transformed into a range of products like wires and tubes.
C. Recycling Copper
Beyond processing primary ores, recycled copper scrap and alloys are melted, refined, and repurposed into new components. It's estimated that recycling contributes to around 50% of the total copper supply in the industry. In recent years, significant quantities of copper have been reclaimed, with the recycled copper valued at several billion dollars.
The Extraction of Copper
Extraction methodologies for copper hinge on ore types, notably sulfide ores such as chalcopyrite (CuFeS2). These ores require processing for concentration before refining takes place. Understanding the underlying chemical redox processes involved during extraction proves critical in clarifying copper's transformation.
For additional insights on our offerings, including Industrial Arsenic Furnace Custom, feel free to reach out to us for professional guidance.