How can North Korean workers get the reconfirmation of their algerian entrial material?

I'm north korean interpreter. My korean workers are supposed to enter under contract with chinese construction company, which has already been working there. These workers' passport copies, qualification cards, health cards, etc. are already confirmed by the concerned ministry of north korea. Can you explain the related procedures for reconfirming of these confirmed materials from the Embassy in Beijing?
Your early forward reply will be highly appreciated. Thanks.