Research On Preparing Nanometer Ferric Yellow From Pyrite Cinder

Pyrite cinders is a solid cinder produced by sulfuric acid industry. The comprehensive utilization can not only reclaim the resources but also reduce pollution on environment. Iron oxide pigments have been made from high quality FeSO₄·7H₂O. It is one of the most prospects ways for comprehensive utilization of the pyrite cinders.Ferric yellow produced from FeSO₄·7H₂O, and the FeSO₄ ·7H₂O is produce from the pyrite cinders which output from Jinshandian iron materials sulphuric acid plant to the Wuhan Iron and Steel Group Company , the whole process was studied. The difference from the traditional technology which used acid method to prepare ferric yellow pigments, we use NaOH to prepare a-FeOOH seed, and in secondary oxidation iron sheet is replaced by dripping NH₃·H₂O. Despite NH₃·H₂O is consumed in chemical reaction, (NH₄)₂SO₄ can be reclaimed for the chemical fertilizer or ammonia, and ammonia can be recycled as precipitating agent. So the resources are utilized reasonably.The seed preparation is a key step in Nanometer ferric yellow production. In this phase the formation, variation, physical phase, size and morphology of α-FeOOH seed are studied by using NaOH as precipitating agent. The effect of initial [Fe²⁺] concentration, oxygen-flow and alkali ratio on seed formation are discussed. The results show that The ferric yellow seed which is deep yellow, very fine, uniform and needlelike can be gained under following conditions(temperature: room temperature;oxygen -flow:3⁴ L/ (L·min);alkali ratio:0. 3;initial Fe²⁺ concentration: 1mol/L).The color of seed continuously changes with time from hoariness to celadon to olivine to khaki to deep yellow.In secondary oxidation the effect oxygen -flow, seed ratio, pH value, oxidation temperature etc on ferric yellow formation are discussed. From the experiment we draw the best oxidation conditions [oxygen -flow 2.5 U (L·min), seed ratio:25%, pH value of solution: 3-4, oxidation temperature:85℃]. Physical phase of Nanometer ferric yellow is a-FeOOH (acicular structure) and all properties of ferric yellow we have determined is reached first grade standard and the particle diameter are approximately 20 nm.