Study On Reduction And Metal Separation Of Oolitic Hematite

Steel demand continues to increase with the rapid development of infrastructure construction. The Iron ore resources which easily to be exploited are increasingly depleted, and the same time, China's iron ore depend on importation in a long-term. The development and utilization of the low grade iron ore resources which is rich in reserves and difficult to choose is gradually emerging, the low grade iron ore mainly include Oolitic hematite. It also has an important meaning to ensure the stable development of steel industry. Oolitic hematite is widely distributed in China and accounts for nearly 1/9 of the whole iron ore in China, it mainly includes Ningxiang Oolitic hematite and Xuanlong Oolitic hematite. the ore being difficult to separate and reduct is due to the extremely fine dissemination size, complex associated relationship and properties.The oolitic hematite ores taken from HeZhang of Guizhou province was analyzed. The mine has the typical oolitic structure, the structure of Ooide is mainly internal concentric ring banded. ooide is round or oval shape. The main elements of the ore are mainly Si, Al, Fe, P, etc. Iron mainly exists in the form of hematite. the main gangue minerals are quartz, silicates, apatite, chamosite etc.Oolitic hematite is reduced by microwave heating. The reducing agent is graphite and the analytically pure calcium hydroxide(Ca(OH)2) was used as a basic oxide to adjust the basicity of the samples according to the experimental parameters. In this study, the atomic ratio of Carbon in the reducing agent to Oxygen in the iron oxides of the oolitic hematite,the time and the binary basicity are all taken into consideration to understand the effects on reduction and metal separation by microwave radiation, the test methods of reduction product are microscope, SEM, XRD and chemical composition analysis. The microscopic morphology, product and metallization rate of the samples in different conditions were studied. The grade and recovery of iron concentrate after magnetic separate were tested. The characteristics of the wave heating of iron concentrate are selective heating and rapid heating. The heating rate of graphite is the fastest, followed by oolitic hematite, calcium hydroxide is worst. The amount of reducing agent added in the sample is greater, the heating rate is faster, the amount of additive is bigger, the speed is more slow. The mixed sample can be heated up to 1100 C in the 50 min. Reduction studies show that iron after reacted mainly exists in the metallic iron, iron, iron olivine spine, Increasing the time and carbon fitting ratio is advantage to the reduction and separation of oolitic hematite, binary basicity in a certain range is conducive to the reduction and separation of metal iron. Metallization rate can reach 94.7%, iron concentrate grade is 88.6%, iron recovery rate is 93.3% in on the condition of the carbon fitting ratio is 1.3, the basicity of the sample is 1.5, and the holding time is 3.5h.