We are entering Beijing for 2 nights, and exiting Beijing to Kazakhstan 67 hours later. However, we

We are entering Beijing for 2 nights, and exiting Beijing to Kazakhstan 67 hours later. However, we have a stopover in Urumqi between Beijing and Kazakhstan. We will be in Urumqi airport for about 7 hours. That means we will not leave that airport until about 78 hours after we first enter China. Can we do this on a transit visa or do we need to get a tourist 30 day visa?