Study On Iron Recovery And Arsenic Reduction Of Pyrite Cinder

Pyrite cinder is the waste of the process of the acid production which using the pyrite as the raw material. The content of the iron in pyrite cinder is 30%-60% in general. Using the pyrite cinder to produce iron concentrate can make the pyrite cinder to be complement to our iron resources in some degree. The content of sulfur in pyrite cinder is higher in China, and it is about 1-4.8%. Sulfur can cause the steel to be thermal brittleness, which can reduce the ductility and toughness, particularly, the impact value and toughness. Some pyrite cinder has high level arsenic, which is about 0.2-0.65%. Arsenic can make steel cold crisp, influence the microstructure of the steel and reduce the mechanical properties. Arsenic can also cause a series of technological problems and environmental issues as a harmful element. Removing the sulfur and arsenic in comprehensive utilization of pyrite cinders is the research focus.In this thesis, the status of the utilization of the pyrite cinder, the status of iron recovery and desulfurizing, and the status of removing the arsenic for some ore are summarized respectively. This thesis researches on the pyrite cinder of a chemical company in Wuhan and analyzes the mineral forms and occurrence of the cinders. It also analyzes the feasibility of the gravity concentration, magnetic separation and froth separation based on the process mineralogy. Low intensity magnetic separation is used to recover the iron, while froth flotation and chemical leaching are used to remove sulfur and arsenic respectively. The result proves that the removal of impurities by froth flotation is not obvious, so chemical leaching is used to removing impurities and improving the iron grade. The optimal parameters of low intensity magnetic and chemical leaching are determined by single factor tests. The optimal conditions are displayed as followed. The grinding fineness is that the size fraction less than 0.038 mm occupies 80%. The concentration of the magnetic separation is 40%, and the magnetic intensity is 0.2 T. Using the hydrochloride as the leaching reagent, making the concentration 40%, setting the ratio of acid and solid at 1:25, the pyrite cinder are leached in 40 minutes when the stirring speed is 150r/min. The concentrate is cleaned for three times with water. Through the low intensity magnetic separation and chemical leaching, qualified iron concentrate can be got, in which the grade of iron is 63.35%, the content of sulfur is 0.325%, and the content of arsenic is 0.083%.This research is used to prepare the qualified iron concentrate from pyrite cinders, which have important significance in reducing the iron cost, relieving the tension of iron resources, improving the comprehensive utilization of the resources and protecting the environment.