Method of stabilizing solutions of chelated polyvalent metals

In a method of removing hydrogen sulfide (H.sub.2 S) from a gas by contacting the gas in a reaction zone with a reaction solution of a chelated polyvalent metal, thereby producing elemental sulfur (S), removing the elemental sulfur, regenerating the reaction solution, and recycling the regenerated reaction solution to the reaction zone,

• the improvement comprising introducing into the reaction zone a free chelating agent at the rate defined by the following equation:
• ##EQU3## where R is the rate of addition of the free chelating agent in lbs/hr;
• A is specific adsorption of the chelating agent on free sulfur in gm/lb;
• and
• S is the rate of free sulfur production in lb/hr;
• the rate R being sufficient to prevent the loss of the chelated polyvalent metal from the reaction solution due to the promotion of the disassociation of the chelated polyvalent metal into a free chelating agent and a free polyvalent metal and subsequent adsorption of the free chelating agent by the elemental sulfur and to maintain the content of the free chelating agent in the solution at about 0.1 to about 1.0% by weight of the chelated polyvalent metal.