Study On Product Engineering Based Fe₂O₃ Preparation From Galvanized Steel-washing Waste Acid

Based on the concept of chemical product engineering, this paper researched the process of preparing iron oxide red from galvanized steel pickling waste liquid, and proposed iron-based pigment product development strategy which is step by step segmentation. This paper studies three stages, the first stage, the first stage, red iron oxide pigments SAR is analyzed; the second stage, the technical conditions of preparing Fe2O3 was explored, the factors of red iron oxide pigment synthesis process was studied by air oxidation-hydrothermal and fixed bed oxidation. The three-stage, ferrous was concentrated by evaporation-cooling crystallization from galvanized steel pickling waste liquid.The first stage, iron pigments SAR was studied by the iron red pigment particle size, crystal morpHology and material. The particle size is from 100nm to 150nm, spHerical crystal morpHology, purity more than 95%, the pigment product performance meet the national first-level standards.The second stage, study on the synthesis of red iron oxide. In this paper, two synthetic red iron oxide method were proposed:air oxidation-hydrothermal and fixed bed oxidation.air Oxidation-hydrothermal method mainly studies on the impact of the initial concentration of ferrous chloride, the initial pH, the air velocity, the hydrothermal reaction time and temperature, the affect of zinc ions. The results showed:the initial concentration of FeC12 1.5mol/L, pH 9-10, the air velocity about 300L/h, hydrothermal temperature 110℃, the intermediate oxidation product will be a red-brown crystalline 8-FeOOH, after the synthesis of hydrothermal, the product was obtained as a particle size of about 200nm, spHerical α-Fe2O3; Presence of zinc ions have a certain influence on the crystal morpHology of oxidation products, and with the increasing of zinc ions concentration in the system, the product color change from red brown to dark brown, crystal morpHology gradually shift from the needle to short rod, finally gathered to the massive agglomeration. Fixed bed oxidation mainly study on the effects of oxidation temperature and oxidation time on product purity, hue, oil absorption and particle size. The results showed that:the optimal technological conditions of preparing high quality red iron oxide are oxidation temperature 400℃, oxidation time 60 min, the purity 99.5%, color bright, particle size form 100nm to 150nm, oil absorption around 24.1%. the reaction process has time temperature equivalence principle. With the ferrous chloride purity increasing, iron oxide red pigment was bright red color, oil absorption at 20% with standards. As the reaction temperature rise, the reaction time become shorten, indicating that the reaction temperature with time equivalency; iron oxide pigment properties meet the standards GB/T1863-2008 which is prepared from the purity of more than 95% ferrous chloride.The third stage, study on the purification process of galvanized steel pickling waste liquid. In this paper, galvanized steel pickling waste was purified by evaporation and concentration-cooling crystallization, per 100ml water solution was evaporated at 50ml, the cooling temperature set at 20-25℃, more than 55% of the ferrous chloride crystals which the purity reached 99.2% is precipitated.