Over a few days I managed to visit a number of the sites:

Hayle - port for exporting tin

Wendron mining district - the Poldark mine with its interesting museum and exhibits

Portreath harbour - port for importing coal and exporting tin; many old mine workingws in this area

St Agnes - many derilict mine wotkings

Luxulyan - a mining village and Treffrey viaduct

Tamar valley - several derilict smelters seen from the train to Gunnislake

I visited all of the above by train or bus from Truro