This is rubbish.
Industrial output grew under the 1970-1974 Conservative government. It also grew under the 1979 - 1997 Conservative government.
It shrunk under the 1974-1979 and 1997-2010 Labour governments.
In addition, coal mines just keep on closing. Britain's largest shut last month:
http://www.guardian.co.uk/business/2013/mar/07/650-jobs-daw-mill-coal-mine.
Even a coal industry subject to massive levels of closures was still unsustainable.
No more sustainable was the likes of British Leyland, subject to 523 walkouts by Red Robbo. Thatcher didn't destroy it, Labour did.
Coal mines keep closing now thanks to a lack of investment in previous decades, Thatcher seemingly took the decision that it would be easier and cheaper (in the short term) to close the pits and destroy communities, instead of invest in new technology to improve efficiency and make the industry profitable once more. There's plenty of coal out there that cannot feasibly be excavated now that collieries have closed - it would simply be too costly and difficult.
Thousands of jobs were lost and whole families thrown into turmoil. Most miners did not like the job itself, but it was a way of life and all that many families had known for generations. You only have to visit former coalfields and see the depravation that still remains.
She was a very powerful and commanding woman, which is all that I am willing to say for her. But she used her power to divide the working classes to acheive her own ends, and I, personally, cannot see how anyone can defend her policies, or the way she enacted them. As mentioned, Scargill has a lot to answer for - but he wasn't the one ordering the Police to act like a private army, or trying everything possible to get scabs back underground.
I'm not old enough to remember Thatcher's time in power, but I'm from a mining family and have a deep interest in her era, which has led to be doing a lot of reading and research for my own interest. I for one have no sadness to see her dead. However, her death does nothing to heal the deep wounds she inflicted on parts of this country that seemingly remain to this day.