is becoming gradually uneconomic and it was estimated that mining would slow down and stop by 2020. In the meantime the mill will be kept up to its 182,000 tonnes per day capacity with sulphides from Radomiro Tomic and Alejandro Hales. The underground mine will start up in 2018 and when it reaches full capacity of 120,000 tonnes per day in 2030, the balance of the tonnage will come from the Alejandro Hales underground mine. It is estimated that extractable underground reserves below the present pit total 1,150 million tonnes of ore grading 0.76% copper and 0.052% molybdenum. This remarkable mine was for many years the world's largest annual producer until overtaken recently by Escondida and it is one of the largest ever copper mining excavation. It has produced over 29 million tonnes of copper in total, far more than any other mine . Radomiro Tomic The Radomiro Tomic deposit, 5 km north of the main pit, was discovered in 1952 when Anaconda conducted an extensive churn drilling programme to explore for oxidised ore to the north of the Chuquicamata pit. It was named Chuqui Norte but they did not develop it, largely because the technology had not been developed, particularly SX/EW. Two smaller areas of interest were found and the overall results showed that the Chuquicamata complex of mineralised porphyries is no less than 14 km long. The deposit is covered with some 100 metres of alluvium and in 1993/94 Codelco estimated a resource base for the operation of 802 million tonnes of oxide ore grading 0.59% copper and 1,600 million tonnes of refractory (sulphide) ore. The deposit covers an area of 5 km x 1.5 km. Mining started in 1997 and is again a conventional truck and shovel operation followed by crushing, pre treatment and stacking before acid leaching. Copper is extracted by SX/EW. Leached ore is removed by bucket wheel excavator followed by secondary leaching. It is likely that the 'refractory' sulphide ore will be mined and used to keep the Chuquicamata mill full during the changeover to underground mining. The last published production by Radomiro Tomic, from Cochilco, was 379,600 tonnes in 2013. Northern expansion of Mina Sur Between the main pit and Mina Sur there remains a substantial tonnage of so-called exotic copper in the channel of paleogravels (ancient gravels) between the two and which were mined in Mina Sur. The minerals, thought to be