Effect of BaO and MgO on structure and properties of aluminate slag with various CaO/Al_(2)0_(3)ratios

To provide theoretical guidance for performance stability control of low-reactive mold fluxes,the effects of BaO and MgO on the structure and properties of aluminate slag with various CaO/Al_(2)0_(3)(C/A)ratios were investigated using the Fourier transform infrared spectrometer,Raman spectroscope,hemispherical melting point instrument,rotational viscometer and X-ray diffractometer.The results indicated that with BaO and MgO addition,the structure polymerization was first weakened and then enhanced at C/A of 1.1,and the transition contents corresponded to 8 wt.%BaO and 2 wt.%MgO,respectively,while the structure polymerization decreased continuously at C/A of 1.3.Since the viscosity change was well consistent with the structure evolution,the polymerization degree played a more prominent role in the slag viscosity than superheat degree when the melting temperature difference was within 40℃.The break temperature decreased initially and then increased with augment of BaO and MgO at C/A of 1.1,while it manifested a decrease trend with BaO addition,and it decreased obviously but then turned to increase with MgO increment at C/A of 1.3.The crystallization phase and crystallization ratio kept stable with BaO increment,while the crystallization ratio rose greatly with MgO promoting LiAlO_(2)precipitation at C/A of 1.1.The crystal types of all experimental slags were mainly Ca_(12)Al_(14)O_(33)and CaF_(2)at C/A of 1.3,and the precipitation of crystalline phase BaAl2O4 demonstrated a rising trend,while that of Ca_(12)Al_(14)O_(33)gradually declined with BaO augment.

Agglomeration and bonding mechanism of typical metallurgical solid wastes

The agglomeration of solid wastes is a key factor for subsequent utilization,while the difficulty in agglomeration and high cost have become common problems in the recycling process.The disk pelletizing process was adopted,based on the optimization method by liquid binder addition,and the influence mechanism of the ratio of typical solid wastes as blast furnace dust(BFD)and sludge generated by oxygen converter gas recovery(OGS)was explored.Meanwhile,the effect of binder solution concentration on the quality of green pellets was studied.Derived from the contact angle detection and infrared spectrum analysis,the liquid bridge model was established to study the bonding mechanism.The results showed that OGS had stronger adsorption effect with binder,and the hydrophilicity of BFD was better.When the concentration of binder was higher than 0.2 wt.%,the contact angle between the binder and BFD was bigger than that with OGS,while the capillary force between particles reduced with larger contact angle.The increment in the binder concentration increased the viscous force between particles and the maximum separation distance.The ultimate drop strength and compressive strength were related to the type of viscous force,and the compressive strength reflected the strength of the force between particles intuitively,while the drop strength represented the comprehensive forces of green pellets.Reasonable combination of BFD and OGS was available for pelletizing process,while the ratio of BFD should not exceed 32.0%,and binder C was added in the form of solution with the addition amount of 0.4 wt.%,which can reduce the cost of binder by 20–30¥/t.

Drop strength measurement of green pellet based on drop-rebound mechanism

The construction of blast furnace charge structure based on pellet and the development of short process from non-blast furnace to electric furnace will be an efficient way to accomplish"carbon peak,carbon neutral".Since drop strength is one of the most crucial quality indexes for green pellet,the crack detection in the collision process is an indispensable segment;however,the present crack determination is basically completed manually.Due to a series of problems including high labor intensity and poor detection conditions,it is urgent to develop an accurate,convenient and fast standardized method for drop strength detection.In view of the above issues,combined with plenty of experimental studies,it is found that whether rebound occurs after the collision of green ball can be used as the basis for judging if there are cracks on the surface,and the mechanism of this segment is explained by the energy conversion of collision process that the plastic deformation of the collision is a cumulative process.Each collision will cause a slight displacement of the iron ore particles;until the cumulative displacement exceeds the binding force between the particles,they will slip in a large range,that is,cracks will occur.The drop strength can be detected based on the drop-rebound mechanism determining crack generation during collision process by high-speed cameras,and the method is fully applicable to oxidized pellets with particle size of 8-16 mm though various pellet plasticities and masses increase the difficulty of bounce height monitoring.Based on the drop-rebound mechanism of green pellet,three methods for automatically detecting the drop strength are proposed,which are high-speed camera,photoelectric sensor and pressure sensor methods.