Nigeria Chemical Industry Importer Companies

I have a client that is about establishing a fertilizer production plant in Nigeria. The major raw material will be Natural Gas. Can you advice on rough design and cost for a 500,000/annum metric ton of manufacturing and blending both wet and dry NPK and Urea. Is it different or the same plant that is used in manufacturing and blending both wet and dry NPK and urea? Please do get back to me especially with a ball park cost as soon as you can using a 500,000 mt/yr basis