It is basically the increase out of the DRC last year has been in excess of demand, plus planned production increases by a couple of large companies.
ERG Metalkol has spent US$625M on the roan tailings facility. Production aimed at around 24,000t/a cobalt increasing in a few years to 50,000t/a.
https://www.eurasianresources.lu/en/pages/bdp/metalkol-rtr-the-roan-tailings-reclamation-project
Chemaf are also increasing supply rapidly, especially when Mutoshi is up and running....
"Chemaf is developing a processing plant at the site with capacity for 20,000 tonnes of copper and 16,000 tonnes of cobalt per annum."
http://www.chemaf.com/
Somika is another company increasing supply, though information on them is limited.
When Katanga comes back online at about 34,000t/a, probably next year now, that will also be a large increase in production by itself. The market initially reacted to Katanga's suspension of cobalt production by going up a bit in late November, but has since collapsed.
There are also high stockpiles in China of Cobalt Hydroxide, which some companies have been forced to de-stock (like Huayou ) This has also helped push prices lower.
G Heppel gives a good indication of the cobalt market/problem in the short term in the following document from CRU International from page 58......
Basically the price of cobalt went to high as there was a shortage of cobalt metal, last year, not cobalt chemicals. The trend is set to continue until about 22/23
http://www.fyiresources.com.au/media/files/Presentations-CRU-Perth-Tech-Metals-Briefing.pdf
The real elephant in the room is the new Tesla takeover of Maxwell Technologies a couple of weeks ago. If Tesla manage to marry up ultracapacitors with their battery packs, they could solve the problem of needing cobalt in lithium batteries. The cobalt is to stop thermal runaway, which tends to happen when batteries have high rates of charge or discharge applied. Using ultracapacitors to store sudden charges or discharges, plus take or resend energy to the battery slowly, could solve the problem of thermal runaway.
https://www.teslarati.com/tesla-energy-ultracapacitor-battery-maxwell-technologies-acquisition/
Tesla have made no secret of their intent to reduce cobalt use to zero.
https://cleantechnica.com/2018/06/09/cobalt-free-car-batteries-in-the-works-for-panasonic-tesla/
Cobalt according to @ozblue is doomed ( Soon )
