An environmental waste company has been fined more than £530,000 after a powerful gas explosion flung two employees into the air and left them with life-changing injuries. <br /><br />Tomasz Patek and Robert Tyrko were replacing pipework on a large metal tank when sparks from the grinder they were using ignited a huge explosion. <br /><br />Shocking CCTV footage of the explosion in Nottingham shows the moment the tank is catapulted into the air. <br /><br />The huge tank is later seen impacting the earth again - nearly ten seconds after it was launched.