Purchasing aluminum UBC scrap, 300 tons monthly, FOB Vietnam

We would like to purchase aluminuum scrap, beverage cans.
Al content (Minimum): 96%
Impurity ratio (Max): 4%
Demand: from 300 tons / month X 12 months. 
Total contract demand: from 3,600 tons / year
Destination: Da Nang port, Vietnam.
Term of delivery: FOB.
Mode of payment ：L/C or TTR.