acid
belt
broken
buildings
cable
close up
coal
containers
conveyor
copper
corrosion
designs
details
energy
engineering
engineers
equipment
framework
freight
gave up
gear
geological
gold
gray
history
hoist
industry
iron
lifting
machinery
machines
mechanical
metals
minerals
mining
old
plant
processing
pulley
red and hot
rusty
scrap
steel
structure
technology
tough
transport
wheel