Effect of CaO and CaCO3 on Reduction Rate of Iron Ore Pellets Containing Carbon

The effect of metallurgical fluxes CaO and CaCO3 on the reduction rate of iron ore pellets containing carbon in nitrogen atmosphere has been studied by a weight-loss thermal balance. The experimental results showed that adding CaO or CaCO3 can promote reduction reaction as the added CaO or CaCO3 probably decrease the apparent activation energy of iron ore concentrate-carbon-CaO or CaCO3 reaction, and the reduction rate constant changes with mass percent of CaO and CaCO3. The kinetic analysis also showed that the rate-controlling step of the reaction is inner gas diffusion.

REDUCTION BEHAVIOR OF IRON ORE PELLETS CONTAININGCARBON UNDER NON-ISOTHERMAL CONDITION

The reduction behavior of iron ore pellets containing carbon under non-isothermal condition in the temperature range from 573 to 1373 K was investigated in a laboratory scale setup. The test results show that carbon content has no obvious effect on reduction degree of composite pellets (C/O mole ratio=1.0) by CO in the temperature range from 573 to 1373 K under linear temperature-rising program; reduction degree of iron ore pellets containing carbon is large in 90%CO-10%CO2 mixture than that of in 100%CO atmosphere or in 80%CO-20%CO2 mixture; the s type temperature-rising program has a better effect than that of linear one in increasing the reduction degree; and reduction degree of slower linear temperature-rising program is greater than that of faster one, but the final reduction degrees, i.e., those at the highest temperature are about the same for various CO partial pressures or temperature-rising programs. The kinetic analysis also shows that the reduction of iron ore-carbon composite pellets by CO or CO-CO2 mixture under non-isothermal condition should be controlled by surface reaction, and the apparent reduction activation energy changes with the reduction progress under various test conditions.

Self-reduction of Manganese-rich Slag Briquette Containing Carbon

The self-reduction experiment of manganese-rich slag briquette containing carbon was carried out in a high- temperature carbon tube furnace. The main factors affecting the reduction rate were analyzed, and the kinetic model of reduction was established. The results show that the increase of basicity of briquette has an obvious effect on im- proving reduction rate. When the carbon ratio of briquettes is 1.2 and its basicity is 1.0, the reduction rate can reach 90 %. It can accelerate reduction process and decrease reduction time when the appropriate flux CaF2 is added to the briquette. The apparent activation energy of chemical reaction is 24.07 kJ/mol, and the apparent activation energy of internal diffusion is 107.55 kJ/mol by calculation. Therefore, the reduction rate of briquette is determined by the mass transfer of CO in the product layer.

Phase Equilibria of the Aqueous Systems Containing Lithium and Carbonate Ions

1 Introduction Alkaline lakes are widely distributed in the area of the Qinghai-Tibet Plateau.Most of the salt lakes are famous for their high concentration of lithium,potassium,magnesium,boron(Ma,2000).In recent years,as a new energy material,lithium and its compounds are widely used in the new area,such as aerospace industry,nuclear

SINGLE IONIC CONDUCTI0N OF POLYSILOXANE CONTAINING PROPYLENE CARBONATE GROUP AND LITHIUM POLYMERIC SALTS

The polysiloxane containing propylene carbonate side group and several lithium poly-meric salts were synthesized. The structure were confirmed by IR, NMR and XPS. Theblending systems of polysiloxane containing propylene carbonate group with different lithiumpolymeric salts were studied by ion conductivity XPS and DSC. Different lithium poly-meric salts in the blending system lead to conductivity arranged in the following sequence:poly(lithium ethylenebenzene sulfonate methylsiloxane)>poly(lithium propionate methyl-siloxane)>poly(lithium propylsulfonate methylsiloxane)>poly(lithium styrenesulfonate).In the blending system the best single ion conductivity was close to 10^(-5) Scm^(-1) at roomtemperature. XPS showed that at low lithium salt concentration the conductivity increasedwith the increasing content of lithium salt, in consequence of the increase of free ion andsolvent separated ion pair. At high lithium salt concentration the free ion was absent andthe solvent-separated ion pair functioned as carrier.

Comparative Analysis on New Type Carbon Free Lining and Traditional Carbon Containing Lining Applied on 120-ton LF-RH Refining Ladles

In some steel making workshops, the existed inher- ent weaknesses of traditional carbon containing brick working lining, such as joint opening, vertical cracking of lining, and excessive erosion of brick edge, made it hard to satis]~ the demands of advanced steel produc- tion. A new-type carbon free corundum spinel brick and castable were developed based on the matrix optimized analysis, successfully applied for ultra-low carbon steel production. The advantages of the newly developed car- bon free working lining are mainly as follows： I ） the inherent weaknesses of joint opening, vertical cracking of lining, excessive erosion of brick edge, etc. are sur- mounted successfully, which improves the operational safety of ladles; 2 ） the outer temperature of the ladle shell decreases by 45 -50 ℃ compared with that of the traditional carbon containing brick lining; 3） the service life of new-type working lining is 150 -170 heats, near- ly doubling that of the traditional carbon containing brick lining; the specific eonaumption of refractories per ton steel decreases by about 20% ; 4） the carbon pickup of mohen steel is not obvious which is merely 5 - 10 ppm, which satisfies the demands of low ＆ ultra low carbon steel production.

Studies on Zeolite Modified Electrode(Ⅰ)─Ascorbic Acid Sensor Based on Carbon Paste Electrode Containing Fe(Ⅲ)Y Zeolite

A new ascorbic acid sensor constituted of carbon paste and Fe(Ⅲ)Y zeolite was studied.The characters of the sensor such as linear range. potential window、apparen Michaelis constant、response time、stability and accuracy wee investigated. The experimental results indicate that the analytical performance of the sensor is satisfactory.

Recent Progress of Carbon Nanotubes Reinforced MgO-C and Al_2O_3-C Refractories

Carbon nanotubes （CNTs） have been extensively studied over the last two decades since they possess excellent properties.CNTs have been considered as new promising reinforcements for carbon containing refractories （CCRs）.Current research progress of the CNT-reinforced MgO-C and Al2O3-C refractories was summarized in this mini-review,and the CNT-reinforced CCRs possess remarkable mechanical properties and superior thermal shock resistance compared to CCRs without CNTs.

Structural and mechanical properties of amorphous carbon films deposited by the dual plasma technique

Direct current metal filtered cathodic vacuum arc （FCVA） and acetylene gas （C2H2） were wielded to synthesize Ti-containing amorphous carbon films on Si （100）. The influence of substrate bias voltage and acetylene gas on the microstructure and mechanical properties of the films were investigated. The results show that the phase of TiC in the （111） preferential crystallographic orientation exists in the film,and the main existing pattern of carbon is sp2. With increasing the acetylene flow rate,the contents of Ti and TiC phase of the film gradually reduce; however,the thickness of the film increases. When the substrate bias voltage reaches -600 V,the internal stress of the film reaches 1.6 GPa. The micro-hardness and elastic modulus of the film can reach 33.9 and 237.6 GPa,respectively,and the friction coefficient of the film is 0.25.

Formation of ZrB2in MgO-C Composite Materials Using In-Situ Synthesis Method

ZrB2 in MgO-C composite materials obtained by both microwave sintering synthesis and in-situ reaction at lower temperature was investigated. The test result shows that 66.67 % of reactant changed into Zrb2, and the other form Al2O3, which could optimize the properties of carbon containing materials. Therefore, the method of in situ synthesizing ZrB2 acting as antioxidant in carbon containing materials is considered as one of best ways to reduce the cost and ZrB2 as refractories is used on a large-scale.

Microstructure Study on Oxidation of Zirconium Diboride

The oxidation behaviors of fused zirconium diboride and chemosynthetic zirconium diboride as well as morphology and composition of their oxidation products were researched by FESEM-EDS and XRD.The two kinds of zirconium diboride were heated at 700℃,900℃,1100℃and 1300℃for 3 h in air,respectively.The results show that Zr02 and B203(Ⅰ)are generated from the chemosynthetic zirconium diboride oxidized at 700℃for 3 h or the fused zirconium diboride oxidized at 800℃for 24 h;B203(Ⅰ)dissolves into water and then H3B03 crystallizes.