A System Dynamics Assessment of the Supply of Molybdenum and Rhenium Used for Super-alloys and Specialty Steels, Using the WORLD6 Model

The extraction, supply, market price and recycling of the metals molybdenum and rhenium were modelled using an integrated system dynamics model. The resource estimates made here resulted in significantly larger estimates than earlier studies for molybdenum. Present molybdenum resources are about 75–80 million ton and about 7 million ton has been mined to date. The ultimately recoverable resources (URR) for molybdenum are about 65 million in primary resources and about 45 million ton in secondary sources, a total of about 111 million ton, and after considering technical extractability, evaluating several hundred different geological deposits, the extractable amount is about 90 million ton. For rhenium, URR is about 21,000 ton contained in mostly in molybdenum and copper, but some come from nickel, wolfram and platinum group metal ores. The model outputs show that molybdenum and rhenium are finite resources, and that they may become exhausted unless the degree of recycling will be significantly improved. Peak production is estimated to take place in 2060 for molybdenum and rhenium, with peak in stocks-in-use around 2090. The molybdenum and rhenium recycling rates are generally low. Both market intervention mechanisms and governance incentives should be used to increase recycling. The metal extraction and ore grades were modelled with good success when tested against observed data. The model predicts a significant decline in molybdenum supply after 2100 under the present demand combined with the present regime of recycling. The supply situation for rhenium is dependent on the situation applicable for molybdenum ore availability and rhenium recycling rate.