Classification of Extractant Products and Analysis of the Principles Behind Extraction Technologies

The size of the extractant market is directly determined by global demand for various metals and the share of hydrometallurgical processes. In recent years, demand for nonferrous metals has generally been on the rise. In theory, all metals can be processed via hydrometallurgy. At present, copper and rare earth elements are among the most widely used in hydrometallurgical applications. Thanks to the remarkable success of copper hydrometallurgy in recent years, research and development in this field has gradually expanded to other nonferrous metals such as zinc, aluminum, manganese, and nickel, resulting in a broad and promising market for extractants.

Extractants can be classified into hydroxamic acids, amines, and phosphorus-based compounds. Hydroxamic acid extractants are primarily used for the extraction of metals such as copper, zinc, cobalt, and nickel; amine‑based extractants are mainly employed in the extraction of rare and precious metals like uranium, gold, and silver; while phosphorus‑based extractants command a large market share and are utilized in the extraction of metals including nickel, cobalt, rare earth elements, and zinc. As metal extractants represent a niche segment of the chemical industry, they have long been dominated by major international corporations, with no publicly available data on production volumes or sales.

As hydrometallurgical processes—characterized by low costs, minimal capital investment, and suitability for low-grade ores and polymetallic associated ores—continue to mature, an increasing number of newly established metallurgical enterprises are adopting these technologies, driving steady growth in the extractant market. Take copper extractants as an example: global hydrometallurgical copper production currently stands at 6 million tonnes per year. With the expanding use of hydrometallurgical methods, demand for copper extractants is growing at an annual rate of 25–30%, underscoring a highly promising market outlook.

Extraction is an experimental technique and method that exploits differences in the solubilities of components between two immiscible phases, enabling one or more components to transfer from the original phase into a second phase with higher solubility, thereby achieving separation and purification. Depending on the nature of the two phases involved, extraction can be classified as solid–liquid extraction, liquid–liquid extraction, gas–liquid extraction, and so forth. In chemical experiments, the second phase selected is typically a solvent, a process known as solvent extraction. To facilitate the efficient transfer of substances between phases, chemical reagents are often added to alter the solubility behavior of a given substance in the two phases through specific chemical reactions. This type of extraction is called chemical extraction, and the added reagents are referred to as extractants.

Extraction is the process by which a target substance is transferred from its original phase into another phase in which it exhibits greater solubility. When the transfer is driven by differences in the solubility of the target substance between the two phases, this type of extraction is referred to as physical extraction. If the target substance’s solubility in the extracting solvent is suboptimal, an extractant can be added to react chemically with the target substance, thereby altering its structure and solubility. This extraction method, which relies on chemical reactions, is known as chemical extraction. In addition to solubility, the extraction process is also influenced by other factors, such as the composition of the two-phase system, pH, temperature, and others.