Seoul, Feb 6 (Reporter) One worker died and six others were injured while cleaning waste tanks in South Korea's steel mill, Yonhap news agency said Tuesday citing the fire authorities and police. Seven workers collapsed at about 11:02 a.m. local time (0202 GMT) while cleaning the waste treatment tank at the Hyundai Steel factory in the country's western port city of Incheon. One of the workers in cardiac arrest was taken to a hospital under cardiopulmonary resuscitation, but the 34-year-old passed away. Six other workers received treatment for symptoms such as clouded consciousness and respiratory difficulty. It was confirmed that the workers were removing the sludge of hydrofluoric and nitric acids left in the tank with no gas masks. The police were investigating the exact cause of the incident...////...