A method and apparatus for reducing mercury in industrial gases such as the flue gas produced by the combustion of fossil fuels such as coal adds hydrogen sulfide to the flue gas in or just before a scrubber of the industrial process which contains the wet scrubber. A contactor in the form of a porous membrane is used. The spring is positioned such that with a hitch shank centered within the hitch receiver, the hitch shank moves the spring to a center position of the elongate slot thereby indicating that receiver and shank are mutually free for disengagement. The amine-based reducing agent includes an aromatic amine and an aliphatic amine, and a weight ratio : therebetween is 5:1 to 1:50.