Best Trade Solution

What is the industry standard as it relates to financing of cola for selling to clients in different countries. We have a UAE based clients with offices in India that wants to purchase coal from an Indonesia mine to with buyers in Singapore. Our clients is requesting trade financing that allows them to purchase the coal from the mine as the mine will not load the vessel without payment. Our client has buyers that will issue LOC from their banks to insure payment. How does the industry allow this to happen? Does anyone know of any trade finance sources that will provide the request trade financing?

Please advise and provide feedback and input