Yara International Asa

Lene Sund

Tanja Vojnovic

Patrycja Kita

Tom Rames Jørgensen

Robertus Louwe

Katrine Lie Bøyesen

A method comprising a) mixing and dissolving the solid hazardous heavy metal-containing composition with an acid solution; b) precipitating the heavy metal from the hazardous heavy metal acid compositions by; c) precipitating the heavy metal from the hazardous heavy metal acid composition with a heavy metal-precipitation agent; and d) separating out the heavy metal precipitate from the aqueous supernatant, whereby the heavy metal-precipitation agent comprises a diorgano-dithiophosphinic acid or the alkali metal or ammonia salts thereof.

Method for treating solid hazardous heavy metal-containing compositions

The present application relates to a process for the reduction of NOx from a gaseous effluent generated in the production of fertilizer comprising the acid digestion of phosphate ore in the presence of urea, wherein said gaseous effluent generated has a NOx composition of 70 to 100 mole % NOand 0 to 30 mole % NO, comprising the steps of: a) contacting said gaseous effluent for 0.5 to 15 seconds with ozone, thereby providing a resultant gas mixture wherein NO and NOpresent in the NOx are oxidized to higher nitrogen oxides; and; b) removing higher nitrogen oxides from said resultant gas mixture; wherein urea is present during said acid digestion of phosphate ore in an amount of 0.25 wt % or less based on the weight of said phosphate ore; and; ozone is added to said gaseous effluent in an ozone/NOx ratio ranging between 0.5 and 1.4.

Growing community of inventors

Porsgrunn, Norway

Lene Sund