Preparation and Properties of SiC Assembled Large Block for Blast Furnace Tuyeres

A SiC assembled large block for blast furnace tuyeres was prepared using silicon carbide particles(3-1 and 1-0.088 mm)and fine powder(<0.088 mm),silicon powder(<0.088 mm),industrial carbon black(N990),microsilica,ρ-Al_(2)O_(3) powder,etc.as raw materials.The developed block was compared with a silicon nitride bonded silicon carbide brick,a self-bonded silicon carbide brick and an imported self-bonded silicon carbide block to analyze and evaluate their service performance.The results show that:(1)in the 0-100 mm zone,the SiC large block mainly consists ofβ-SiC and nitrides such as O'-SiAlON,β-SiAlON,α-Si_(3)N_(4),and Si_(2)N_(2)O,the bulk density is 2.68-2.70 g·cm^(-3),the apparent porosity is 14%-15%,and the material structure is uniform;(2)in the 0-100 mm zone,β-SiC nano-whiskers intercalate with nitrides;with the depth increasing,the number of flocculentβ-SiC nano-whiskers increases,while the number of nitrides decreases;when the depth reaches 150 mm or more,the main bonding phases areβ-SiC and mullite;(3)compared with the reference products,the developed SiC large block has a good basic performance,and after alkali corrosion,the mass change rate is-0.1%,which is obviously superior to the imported self-bonded silicon carbide and the homemade silicon nitride bonded silicon carbide materials.

Corrosion and Penetration Resistance of Corundum Bricks to High Phosphorus Oolitic Hematite Reducing Materials

The paper aims at investigating whether corundum bricks can be used for the bottom, of the direct reduction furnace of high phosphorus oolitic hematite. The reducing materials including high phosphorus oolitic hematite, bitumite, Ca（OH） 2 and Na2CO3 at a mass ratio of 1：0. 15：0. 15：0. 03 were mixed and pressed into carbon containing cylindrical specimens with the size of Ф15 mm × 20 mm. The specimens were placed on the corundum bricks and reduced in a high temperature tube furnace at 1 200 ℃ for 40, 60, 80, 140 and 220 min, respective- ly. The corrosion and penetration resistance of corundum. bricks to high phosphorus oolitic hematite reducing materials were analyzed with XRD, SEM and EDS. It shows that the reducing slag formed in the reduction process corrodes the surface of corundum bricks to form a product layer of anorthite and hercynite, retarding the further corrosion of the reducing slag; the reducing slag which has penetrated into the interior of the brick goes through the gaps between the particles and generates anorthite and hercynite, filling the gaps and hindering the reducing slag penetration.

Technology Progress of Refractories for Iron Making in China

This paper reviews the present development situation of refractories for iron making system in China, which includes blast furnace, hot blast stove and coke dry quenching, etc. Varieties and performances of refractories used by the top steel and iron groups such as Baosteel, Wuhan I＆S Group and Anshan I＆S Group for iron making were exemplified and concerned problems were analyzed, together with solutions and suggestions for future refractories R＆D work.

Multivariable Dynamic Modeling for Molten Iron Quality Using Incremental Random Vector Functional-link Networks

Molten iron temperature as well as Si, P, and S contents is the most essential molten iron quality （MIQ） indices in the blast furnace （BF） ironmaking, which requires strict monitoring during the whole ironmaking production. However, these MIQ parameters are difficult to be directly measured online, and large-time delay exists in off-line analysis through laboratory sampling. Focusing on the practical challenge, a data-driven modeling method was presented for the prediction of MIQ using the improved muhivariable incremental random vector functional-link net- works （M-I-RVFLNs）. Compared with the conventional random vector functional-link networks （RVFLNs） and the online sequential RVFLNs, the M-I-RVFLNs have solved the problem of deciding the optimal number of hidden nodes and overcome the overfitting problems. Moreover, the proposed M I RVFLNs model has exhibited the potential for multivariable prediction of the MIQ and improved the terminal condition for the multiple-input multiple-out- put （MIMO） dynamic system, which is suitable for the BF ironmaking process in practice. Ultimately, industrial experiments and contrastive researches have been conducted on the BF No. 2 in Liuzhou Iron and Steel Group Co. Ltd. of China using the proposed method, and the results demonstrate that the established model produces better estima ting accuracy than other MIQ modeling methods.