Heap leaching is a mining process used to extract valuable metals, such as gold and copper, from ore. In this method, crushed ore is piled into heaps and then treated with a leaching solution, typically containing cyanide or sulfuric acid. The solution percolates through the heap, dissolving the desired metals, which are then collected for further processing. After the leaching process, the remaining material, known as tailings, is often left on-site. This method is favored for its cost-effectiveness and efficiency, especially for low-grade ores. However, it requires careful management to prevent environmental contamination from the chemicals used.