Which of the following methods is not used for extracting copper from low-grade ores?

Traditional mining is not specifically considered a method for extracting copper from low-grade ores. This technique typically refers to the extraction of copper from higher-grade ores, where the ores contain a significant percentage of copper that can be economically extracted through conventional mining methods, such as open pit or underground mining.

In contrast, phytomining, electrolysis, and bioleaching are methods that are particularly suited for low-grade ores.

Phytomining involves growing plants that can absorb copper from the soil and then harvesting them to extract the copper. This method is useful for low-grade ores because it utilizes biological processes to recover metal from materials that are not commercially viable through traditional mining.

Bioleaching uses bacteria to extract metals from ores by breaking down the mineral structure. This is particularly effective for low-grade ores where traditional methods may not be efficient.

Electrolysis is a refining process typically applied to copper obtained from other extraction methods, ensuring high purity of the metal rather than being a direct extraction method from low-grade ore.

Understanding these differences highlights why traditional mining is not applicable for low-grade ores, focusing more on the extraction of ores that have a higher concentration of copper.