In the mid-19th century, in 1856, the Royal Asturian Mining Company (Real Compañía Asturiana de Minas) began operating the Reocín mines. As in so many other mining regions, the first essential task was to connect the pitheads with a point from which the ore could be exported.

The nearby Besaya River, which emptied into the Atlantic via the San Martín estuary, provided a suitable location for ships to dock —the logical destination for a railway that could carry the ore extracted from the mines so close to Torrelavega. To make this possible, the mining company itself took on the construction of a dyke to regulate and channel the San Martín estuary in 1878.

Along the stretch between the mine and the estuary, a series of industrial settlements appeared, among them the Solvay factory in 1908. This concentration of mining and industrial activity prompted the creation of a small port at Requejada, financed jointly by the Real Compañía and Solvay. 

The mining and industrial port was eventually established near the town of Hinojedo, where a zinc roasting plant and ore-washing facilities were built. This was also the terminus of a 9 km industrial railway, with a very narrow gauge of just 55 cm, used exclusively for freight traffic.  At its starting point, the line had a branch that connected with Ferrocarril del Cantábrico (the Santander–Oviedo line) at Puente de San Miguel station. 

The ore-loading facilities remained in operation for nearly a century, until road transport gradually replaced the railway. As the quay fell into disuse, the mining line was also abandoned and eventually dismantled. The Reocín mine itself finally ceased production in 2003, when its deposits were exhausted.