not getting full profit from mines

[d'Arthez]

No, the ingame descriptions are inaccurate. The income is dependent on resources. So some mines bring in only 600 / turn, while others can bring in up to 1800 / turn. When deciding on building a mine, simply take a look at the settlement details screen. Once you select a mine, it will show (in a greyish colour) what contributions the buildings in the building queue will make.