Sodium carbonate is widely used in sewage treatment, analytical chemistry, metal mineral processing, and other fields. In photographic film processing, it serves as a fixative, and in tanning, it acts as a reducing agent for dichromates. It is also used as a mordant, a neutralizing agent for nitrogen-containing tail gases, a bleaching agent for straw and wool, and a dechlorinating agent in pulp bleaching. Additionally, it is employed in the production of tetraethyl lead, dye intermediates, and silver extraction from ores.