Chemicals discovered at Mosul University tested positive for sulfur mustard and were likely being used to create weapons.
The United Nations said $100 million is needed to demine Iraq. Mosul alone will require about half that amount.
At least 114 were killed and 11 more were wounded:
Militants executed 15 people in Sheikh Mohammad, near Mosul.
In Mosul, a missile killed 12 civilians. Clashes left two soldiers and 15 militants dead. Six militants were killed in Zuhoor and Noor. An airstrike killed 13 militants. A drone strike killed 14 more.
Four bodies were found in a mass grave in Sinjar. The victims are thought to be Yazidis.
A bomb in Sakkar killed two security personnel and wounded two more.
A sniper killed a peshmerga fighter in Daquq.
In Ghazaliya, a bomb wounded two people.
Gunmen wounded a Sahwa member as he was leaving his home in Tarmiya.
A bomb in Rutba left an unknown number of casualties.
Eight militants were killed in an attack on Imam Weis.
An airstrike on Rawah killed a suicide bomber.