Research On Sulfuric Acid Preparation Under Weak Oxygen Through Roasting High-grade Sulfur Concentrate From Cyanide Tailing

A large amount of pyrite slag produced by pyrite slag containing low iron after acid preparation through roasting stacks for a long time and increases year by year,it not only occupies a lot of land resources and leads to environmental pollution,but also results in a great waste of resources.The waste heat produced by acid preparation cannot be fully utilized as well.Accounting for these problems,in order to make full use of mineral resources and improve the economic and social efficiency of enterprises,low grade pyrite need to be substituted by high sulfur concentrate to prepare sulfuric acid by roasting.This paper focused on investigating the influence mechanism of boiling temperature,flue gas residence time,bottom pressure on the residual sulfur content in slag.This paper also investigated the effects of sulfur grade,oxygen concentration at boiling furnace outlet and negative pressure of boiling furnace outlet on total iron content and magnetic iron content in pyrite cinder.We established a new process of sulfuric acid preparation by roasting high sulfur concentrate under weak oxygen and valence control of iron containing component.On this theoretical basis,the 80kt/a sulfuric acid preparation system only suitable for roasting low grade pyrite was reformed to roast high sulfur concentrate under weak oxygen,including roasting intensity,slag discharge opening of boiling furnace,boiling furnace air distributor,boiling furnace feeding,slag discharge system reform and acid producing system.This study formed a key technology system of sulfuric acid preparation through roasting high pyrite under oxygen weak and valence state control of iron containing components.The original acid preparation process of 80kt/a suitable for toasting low pyrite is reformed to be applicable for roasting high grade pyrite under weak oxygen through the core technology.The process runs stable with 99.6%of start-up rate,245t/d production of acid(100%)which reaches the standard of GB/T534-2002,110t/d production of iron powder which can be directly sold,0.28%of sulfur residue and iron grade of 62.2%,bringing significant economic and social benefit.