Like all mining railways, the history of this route is very modest. The iron-rich mountains near San Nicolás del Puerto led the Scottish company “William Baird Mining Cº Ltd” to acquire the rights to exploit these veins in 1892. This was another example of the presence of British entrepreneurs in Spanish mining, especially in the Seville and Huelva regions. To transport the production from this mine, they built a railway that connected to the nearby Seville-Mérida line, situated to the west of Cerro del Hierro, about 15 km away, following the course of the Rivera del Huéznar.

In 1893, construction began on this branch, which entered service on May 1, 1895. Unlike most mining railways, it was built with broad gauge tracks. This facilitated the operation of the line, granted to the MZA company, owner of the general line at the bottom of the valley. This broad gauge eliminated the need for transferring loads when reaching the general line for transport to the port of Seville (where it had its own loading dock) and industries. A major destination for these materials was the Pedroso Factory, an exotic steel complex just 30 km from the mine and legally linked to it (it was the first owner of the mines), but this factory failed and closed before it could be connected to the mines by railway. Furthermore, this similar gauge also saved the construction of a station at the starting point of the line, a junction on the main track called the “Los Prados Junction,” also known as the “Río Huéznar Junction.”

The line never had passenger service or any other goods transport apart from what was necessary for the mining company, despite several attempts and the great interest of the municipalities it passed through. In any case, and irregularly, it was frequently used by miners traveling from San Nicolás to the mines on the mineral trains. In 1915, the line was transferred from the mining company to the MZA railway company, which in 1941 would be integrated into the new state company Renfe. Finally, due to the decline in mining production, the service on the line was closed in 1970, and the facilities and tracks were kept for a while until a decision could be made about dismantling them, in case mining operations were reactivated. However, this never happened.