Ion exchange purification method is a multiphase complex decomposition reaction between the target component ions in the solution and the solid-liquid exchanger, so that the target component is preferentially transferred from the liquid phase to the solid exchanger, and this process is called "adsorption". Then the ion exchanger saturated by the target component is washed with appropriate reagents, so that the target component is re-transferred to the solution, so as to achieve the purpose of purification and enrichment. The latter process is called "washing", "washing" or "desorption". These two processes are often referred to simply as ion exchange.
Adsorption and leaching are the two most basic operations of ion exchange, and generally there is a washing operation after adsorption and leaching. The washing after adsorption is to wash away the impurity components with small affinity, and the washing after leaching is to remove the eluent in the resin bed. Some purification processes also have exchanger transformation or regeneration operations after washing and rinsing. Figure 7-5 shows the principle flow of the ion exchange purification method.
What are the basic principles of ion exchange in mineral processing
There are many types of ion exchangers, and the most widely used ones are various types of organic synthetic ion exchange resins.
Ion exchange technology is currently widely used in the treatment of nuclear fuel, rare earth separation, chemical analysis, industrial water purification, wastewater purification, preparation of high-purity ion exchange water and extraction and separation of certain metal components from dilute solutions. For example, cyanide ions and flotation agents are removed from gold, silver cyanide liquid and tailings water of the processing plant.
The ion exchange method for purification and enrichment of metal components has many advantages, such as good selectivity, high recovery rate, low operating cost and high quality chemical concentrate. The target component can also be extracted directly from the leached pulp (pulp adsorption method), and the leaching and adsorption operation can be combined (pulp resin method) to improve the leaching rate and eliminate solid-liquid separation operations. The main disadvantage of the ion exchange method is that the adsorption capacity of the exchange resin is small, which is only suitable for extracting the target component from the dilute solution, and the adsorption rate is small and the adsorption cycle is long, so in many fields, the ion exchange method is replaced by organic solvent extraction.
