**1. Introduction**

Smelting is one of the important processes in the pyrometallurgical production of blister copper in which copper–iron sulphides are oxidised to form molten matte and slag. Flash smelting and bath smelting are the major smelting technologies in copper production. Copper concentrates react with oxygen directly in the flash smelting process which has the advantages of high capacity and automatic control. However, fine and dry feeds are required for the flash smelting furnace to enable fast reactions. As a result, considerable feed preparation is required, and the dust rate is relatively higher. It has limited ability to treat scrap and other copper-containing materials with large sizes. Bath smelting is an alternative technology to flash smelting which involves the reactions of copper concentrate with oxygen in the molten bath. Several technologies have been developed based on the bath smelting principles that include IsaSmelt/Ausmelt, Noranda/El Teniente, Vanyukov, Mitsubishi and recently developed bottom-blowing smelting (BBS) process [1–4]. Due to its unique technological features, such as good adaptability to raw materials, high oxygen utilisation and thermal efficiency, and flexible capacity, BBS technology has attracted strong interest from the copper industry [5–14]. In 2016, 13 BBS furnaces were constructed or were under construction with the capacity of 1600 kt/a copper production. The furnace size ranged from Ø3.8 m × 11.5 m to Ø5.8 m × 30 m [5,14]. The fundamental studies including thermodynamics of the slag and fluid dynamic of the molten bath have been extensively conducted in recent years to understand and support the new technology. This review summarises the development of the copper BBS including the history, features and relevant fundamental studies.
