As a consequence of the mineral market evolution and the notable advances in the development of larger bulk carriers, the Compañía Minera de Sierra Menera (mining company) needed to improve its facilities to cope with the sharp increase in production, which in 1973 had exceeded one million tonnes.
The company considered three possible solutions. One was to adapt the existing facilities, which required the construction of new quays and costly dredging. Another is to extend the port out to sea. In the end, the solution chosen was to build a new loading dock in the open sea to guarantee its autonomy from the port and Altos Hornos de Vizcaya. With the dock-type typology, it was also possible to maintain the continuity of the coastal environment.
On 25 January 1974, a ministerial order authorised the construction and operation, for a period of 30 years of a dock for loading ore from the Ojos Negros mines, outside the port of Sagunto, on the land reclaimed from the sea which, in 1915, had been given to the Sierra Menera Mining Company. Subsequently, its use would be extended to incoming transport. The works began in the first quarter of 1975 and finished in 1977. The total length of the dock was 1,652 m and its width varied from 7.2 m to 20.2 m. It allowed a maximum draught of 13 m for calm seas. The Sierra Menera Mining Company operated 14.8 million tonnes of ore and 4.9 million tonnes of cement and clinker during the ten years it was in service, equivalent to 7,100 tonnes per working day.
The facilities located in the land area consisted of a receiving hopper next to the storage yard and a conveyor belt anchored on the deck. This was connected to two other belts leading to the platform, where there were also five hoppers for loading and unloading movements. The system was terminated by a loading machine with a boom capable of reaching a distance of up to 27.2 m. The average loading capacity was 2,000 t/hour, which allowed ships of up to 100,000 tonnes to be loaded. After Altos Hornos del Mediterráneo ceased its activity in 1984, so did Compañía Minera de Sierra Menera in 1987 due to the loss of its main client.