Extraction of iron from pyrite cinder by mixed acid of sulfuric acid and hydrochloric acid

and main factors influencing iron leaching rate were investigated.In order to analyze feasibility of extraction of iron from pyrite cinder

the main elements were determined by using X-ray fluorescence spectrum analyzer (XRF).The crystal type of iron oxide in the pyrite cinder was also analyzed by X-ray diffraction (XRD)to understand the presence forms of iron in pyrite cinder.First

10 g dried pyrite cinder were added to a 250 ml three-necked flask.Then

sulfuric acid and hydrochloric acid of specified concentration and quantity were gradually added into the flask under proper stirring

and were kept at a specific temperature for several hours.After filtration

the solution was diluted to 250 ml with distilled water.The diluted solution was used for determination of iron content in leacheate using the stannous chloride-mercury chloride-potassium dichromate method.At last extraction conditions were optimized.The results showed that the significances of each factor on iron extraction were as follows:concentration of sulfuric acid>hydrochloric acid amount>reaction time>sulfuric acid over-dose coefficient.Iron extraction rate increased with higher reaction temperature and increasing amount of hydrochloric acid.However

there existed an optimum combination of sulfuric acid concentration

reaction time and sulfuric acid over-dose coefficient.The optimal conditions were reaction temperature 118—125℃

reaction time 3 h

sulfuric acid concentration 50%—60%

and hydrochloric acid 0.25 ml·(g pyrite cinder)-1

sulfuric acid over-dose coefficient 1.2.Under these conditions

the extraction yield of iron was 93.1%

much higher than that by a single acid.So

the process can improve utilization of iron resource.