Phase Composition of Aqueous Urea-Ammonium Nitrate (UAN)-Zinc Nitrate Solutions for Sustainable Reuse of Zinc Containing Industrial Pigment Waste.

Sustainable metal recovery from waste is of utmost importance. Zn is a micronutrient that is abundant in many industrial wastes. In this work, the process of converting industrial white pigment waste into a Zn micronutrient contg. nitrogen fertilizers was developed utilizing an HNO3 extn. method. For this purpose, soly. diagrams, polytherms, were constructed of the ternary CO(NH2)2-Zn(NO3)2-H2O and NH4NO3-Zn(NO3)2-H2O systems to det. the corresponding phase equil. and solid material chem. compn. Complex salts contg. Zn and two and four urea mols. were obsd. and the catalytic Zn(NO3)2 effect was obsd. at the decompn. temp. of CO(NH2)2 during thermal anal. Two cryst. phases of NH4NO3, namely III and IV, were obsd. and the corresponding transition temp. decreased with increasing Zn(NO3)2 concn. in soln. Zn extn. in the form of sol. Zn(NO3)2 was performed from the white pigment industrial waste and optimal extn. parameters including HNO3 concn., stoichiometric amt. and temp. were detd. These included a 60 °C soln. temp., 55% HNO3 concn. and 140% of stoichiometric HNO3 amt. This agreed well with the reactive conditions currently used in nitrophosphate fertilizer prodn. potentially enabling direct prodn. of micronutrient contg. NP fertilizers without significant technol. modification. Sensible compns. of UAN-28 and UAN-30 liq. fertilizers contg. Zn micronutrient from industrial grade compds. and pigment waste extd. Zn(NO3)2 were obtained and their physicochem. properties were measured. [on SciFinder(R)]