Mineral zeolite processing
Zeolites are hydrated aluminosilicate minerals of alkali and alkaline earth metals especially sodium, calcium, magnesium, strontium, and barium, which are made of interconnected tetrahedra of alumina (AlO4) and silica (SiO4). Zeolites are formed by various crystalline structures, which have large open pores with a highly regular arrangement of approximately the same size as small molecules. Cations and water are located in their pores. They have a framework structure, with interconnected cavities occupied by large metal cations (positively charged ions) and water molecules.
Zeolites have two main properties: adsorption and ion exchange. These two properties are due to the presence of reactive surfaces, due to the presence of Al3+ in the adsorption sites with Si4+ ions, and the crystalline system of the microfabrics. These properties allow zeolites for several applications. Zeolites have a porous structure, which can accommodate various types of cations. These positive ions are kept relatively free and can easily exchange with others in the contact solution.
In recent decades, this natural substance has found various applications in absorption, catalysis, the construction industry, agriculture, soil improvement, and energy. Different natural zeolites around the world show different ion exchange capacities for different cations such as ammonium and heavy metals. In addition, some of them have the ability to absorb anions and organic compounds. The modification of zeolites is done by different methods such as acid washing and ion exchange. This increases the absorption capacity of these materials to absorb anions and organic compounds.