Abstract: A stable, salt-free iron chelate for use in aqueous alkaline systems is prepared by contacting iron oxide with an aqueous mixture of from 30 to 45 mole percent trisodium HEDTA and from 55 to 70 mole percent EDTA, heating the mixture to dissolve the iron, and adjusting the pH to from 7 to 10 with base.

Abstract: An improved method of treating boiler water which employs an oxygen scavenging compound and a compound to control pH together with a chelating agent, wherein the chelating agent is hydroxyethylethylenediaminetriacetic acid.

Abstract: A process for making Fe-EDTA chelate comprising adding iron oxide at a ratio of <1 mole iron/mole EDTA to a mixture of NH.sub.4 OH and EDTA wherein NH.sub.3 /EDTA mole ratio is from 1.05 to 1.5, heating until reaction is complete, cooling to about 60.degree. C. and adding sufficient NH.sub.3 to dissolve and maintain Fe-EDTA chelate in solution, cooling to room temperature and oxidizing Fe.sup.++ to Fe.sup.+++. The process provides (1) a minimum of foaming and sludge formation during the reaction, (2) rapid dissolution of iron oxide and (3) a chelate product substantially completely in the ferric state.

Abstract: A process for making Fe-EDTA chelate comprising adding iron oxide at a ratio of <1 mole iron/mole EDTA to a mixture of NH.sub.4 OH and EDTA wherein NH.sub.3 /EDTA mole ratio is from 1 to not more than 1.5, heating until reaction is complete, cooling to about 60.degree. C. and adding sufficient NH.sub.3 to dissolve and maintain Fe-EDTA chelate in solution, cooling to room temperature and oxidizing Fe++ to Fe+++. The process provides (1) a minimum of foaming and sludge formation during the reaction, (2) rapid dissolution of iron oxide and (3) a chelate product substantially completely in the ferric state.

Abstract: Ethylenediaminetetraacetic acid and the trisodium salt of N-hydroxyethylethylenediaminetriacetic acid are mixed in water at mole ratios of 80/20 to 52/48, respectively, and a manganese compound is dissolved therein with heating. The pH is adjusted to 7 and water is added to make a solution of manganese chelate which contains 6% by wt. manganese. The resulting solution has good freeze-thaw stability.

Abstract: An improved process of preparing an aqueous solution of the zinc chelate of N-(2-hydroxyethyl) iminodiacetic acid wherein ammonia is added to the aqueous solution during its preparation to increase the solubility of zinc therein.