The Mineral Liberation Characteristics Of RO Phase In Steel Slag

Steel slag contains more than 30% of nonhydraulic minerals?mainly dominated by RO phase?,and its low hydraulic activity makes steel slag difficult to use.Removing the nonhydraulic minerals from steel slag powder can not only increase the active mineral content in the steel slag,but also the separated nonhydraulic minerals products which are the scarce industrial raw materials.The necessary condition for separation is the liberation of the target mineral from the surrounding rock.The basic modes of mineral liberation is mechanical grinding.Microwave irradiation is an auxiliary technology for mineral liberation in recent years.The paper carries out a research to the liberation of the RO phase from the mechanism of mechanical grinding and microwave irradiation liberation,which is to improve the technology of separation and process for steel slag mineral.In order to compare the best breakage mechanism of RO phase liberation in steel slag,the four kinds of steel slag powder with different particle size distribution which have been comminuted respectively by high-pressure grinding rolls?roller press?,vertical roller mill?vertical mill?and ball mill were selected.Each of them was actually sieved into 7 size fractions then made into polished section.The proportion of RO phase grain in the five liberation classes and the phase surface parameters were manually counted.The liberation properties were characterized by the two index parameters of the degree of liberation and amount 75-100% liberated,while the amount of liberation by detachment was described by phase specific interfacial area and free surface percentage.As the RO phase in steel slag is easy to be released from the rock matrix,the amount of liberation by detachment of RO phase in four steel slag powders are large.The priority sequence of comminution equipment in terms of the amount of liberation by detachment is roller press,vertical mill,ball mill.The finer of steel slag powder made by the same equipment,the better the amount of liberation by detachment.Liberated minerals deportment by size fraction shows different characteristics in two region which can be separated by the average dissemination size of RO phase.The first region is liberation properties stability zone in which the degree of liberation is independent with particle size and device.In the second region compressive bed breakage mechanism provides better mineral liberation compared to impact breakage mechanism.The second region is liberation properties decline zone in which the degree of liberation significantly decreases with a corresponding increase in particle size.In order to study the microwave absorption characteristics of the steel slag mineral phase,the relative dielectric constant and loss tangent of the RO phase,Fe₃O₄ and gangue minerals were measured.The relative dielectric constant of Fe₃O₄,RO and gangue minerals are 101.96,21.88,and 7.34,respectively.The relative dielectric constant and loss tangent products are 24.47,10.72,and 0.29,respectively,and the order of the material absorption in a descending manner is same.The heating rates of the Fe₃O₄,RO phase,Fe and gangue mineral in the linear phase were1.68,1.70,0.96 and 0.08?/s,the maximum temperatures of four the materials were 674.3,926.9,534.0,65.0?,respectively.The absorption warming values of the two target minerals were much higher than the absorption warming values of gangue minerals.Steel slag was irradiated by microwave,microcracks appeared in the boundaries of RO phase and gangue mineral in the steel slag,the pores of steel slag particles became larger,the strongest pore distribution peak occurred in 9¹0 ?m,and the porosity of the block was increased by 1.7%.The microwave irradiated steel slag particles are easier to comminution and the mass percentages of-45?m size fractions increased by 11.0%.After microwave irradiation of steel slag,RO phase deportment by size fraction shows different characteristics in two region which can be separated by the average dissemination size of RO phase.The first region is liberation properties stability zone in which the liberation degree of RO phase was increased by 3.5⁵.0%.The second region is liberation properties decline zone in which the degree of liberation improved 23.0%,The larger the microwave irradiation,the better the liberation effect.