Assuming a fairly earth-like planet, perhaps, higher in minerals and resources. And a race of highly industrious, highly cooperative, very enginuitive people. Their science is comparable to our own, but they are total capable of using that science to engineer solutions to the challenges that will ensue.
They begin building their technological wonder. They begin mining out a very large mineshaft, directly down.
They reach the point where the planets crust becomes scolding hot. They then construct a pipeline to the surface so that they can pump in sea water. They cool the rock by hosing it down and then continue mining.
They then reach a point, where the shaft walls are heating up above them. So rather than posting people at each interval with hoses to prevent the wall from collapsing, they create some kind of automated device that mounts to the wall. It pipes in water, heats it against the rocks and then pipes out steam. The steam is sent up to the surface via a high pressure pipe. This steam pressure can be harvested by steam turbines to generate electricity. This good because powering the lift that is used to remove the rubble from the bottom of the shaft is taking allot of power.
So they continue building this shaft down, with the walls fully encased with the steam producing rock coolers. The sky is completely overcast because of all off the evaporated sea water. (They must also have to send up all of the salt at this point. Obviously, the steam and water pipes branch off at each level so that there are just the two main pipes.)
Eventually they get close enough to the planets core that the composition of the matter that they are mining is mostly heavy metals. They stop Physically mining further and use ceramic pipes to send molten metal to the surface under it's own pressure.
Mission accomplished, they now have access to a continuous tap of iron, lead, gold, silver, uranium, or whatever other heavy mineral they need, depending on the composition of their planets core.