Thirteen people who admitted obstructing a railway taking coal from an opencast site to a power station have been given conditional discharges.
The group, from Bristol and western England, were sentenced at Merthyr Crown Court over the 2009 protest.
They were also banned from the Merthyr site, Ffos-y-Fran, and Aberthaw power station in the Vale of Glamorgan.
Meanwhile, a "climate camp" protest has begun near Dyffryn Cellwen, north of Glynneath, near other opencast sites.
In court, the 13 campaigners pleaded guilty to obstructing the railway line used to carry coal from Ffos-y-Fran to Aberthaw.
They were each ordered to pay £60 costs and four of the defendants were ordered to pay compensation between £100 and £250 to Miller Argent, the company which runs Ffos y Fran.
After the case, activist group Rising Tide said: "Opencast mining trashes the landscape, contributes massively to climate change and threatens the health of local people.
'Necks on the line'
"We need to leave coal in the ground, and that's why we put our necks on the line to stop a coal train."
James Poyner, joint managing director of Miller Argent, said: "Their action was very irresponsible.
"They have to realise they're not above the law, however strongly held their beliefs are."
The sentencing came as organisers of Climate Camp Cymru said a camp had been set up camp near Dyffryn Cellwen.
The protest camp is expected to continue until Tuesday.