Kanawha County Commission Emergency Management Director C.W. Sigman speaks at a news conference Wednesday in Charleston, W.Va. John Raby/AP hide caption toggle caption John Raby/AP INSTITUTE, W.Va. — A chemical leak at a West Virginia silver recovery business on Wednesday killed two people and sent about 30 others to hospitals, including one in serious condition, authorities said. The leak occurred at the Catalyst Refiners plant in Institute as workers were preparing to shut down at least part of the facility, Kanawha County Commission Emergency Management Director C.W. Sigman said. A chemical gas reaction occurred at the plant involving nitric acid and another substance, Sigman said at a news briefing. He added that there was “a violent reaction of the chemicals and it instantaneously overreacted.” “Starting or ending a chemical reaction are the most dangerous times,” Sigman said. The chemical reaction that was believed to have occurred during a cleaning process produced toxic hydrogen sulfide, Kanawha County Commission President Ben Salango said. A chemical leak at the Catalyst Refiners plant near Charleston, West Virginia, killed two …