Starting mixes made from domestic materials for metal continuous casting

Requirements are formulated for starting mixes for continuous metal casting. Results are provided for development of starting mix compositions made from domestic materials that satisfy the contemporary requirements of ferrous metallurgy enterprises. Analysis of the behavior during operation of individual starting mix components during warm up and operation is provided.     

焦宝石基喷涂料的研制

以焦宝石、叶蜡石、硅微粉和铝酸钙水泥为原料制备了焦宝石基喷涂料,对比分析了焦宝石基喷涂料与焦宝石-铝矾土基喷涂料的物理性能。结果表明:焦宝石基喷涂料与焦宝石-铝矾土基喷涂料的性能相当,但是该喷涂料成本较低,可部分替代焦宝石-铝矾土基喷涂料修补高炉的衬里,使用效果良好。     

Research in the production of periclase-chromite refractories from beneficiated raw materials

Conclusions Laboratory and technological investigations of periclase-chromite refractories produced from beneficiated starting materials were carried out for the purpose of defining more precisely the required grainsize distribution of the starting components of the mix. The structural characteristics (the nature of the porosity, the development of a fragmented macro- and microstructure, and the formation of a direct intergranular bond) were analyzed in relation to the composition and grain-size distribution of the mix.The process of the formation of direct chrome-spinel-periclase bonds depends primarily on the firing temperature. The degree of the development of direct bonds can be regulated, however, by varying the composition of the mix in addition to which the process can be intensified by adding some of the chromite to the fine-ground part of the mix and increasing the proportion of coarse-grained chromite. An increase in the molding pressure and a decrease in the upper limit of the coarseness of the granular chromite also contribute to the formation of direct bonds.To ensure that the properties of the refractories, more particularly the thermal-shock resistance, are as required and that the standard specifications for the Cr₂O₃ content are met the proportion of the granular chromite in the mix must be 10–15% and that of the fine-ground component 5–10%. It will be necessary to verify the compositions in production conditions and to investigate the durability of the refractories in service.Translated from Ogneupory, No. 7, pp. 30–38, July, 1978.     

The effect of geometrical parameters on the flow field of an opposed jet rim mix head: Equal flow and matched fluids

The effect of geometrical parameters on the flow field present in the mix head used in reaction injection molding (RIM) are presented for Re_d (Re_d = 4Q/πdv, nozzle diameter d, fluid kinematic viscosity v and the volumetric flow rate Q through the nozzle) representative of commercial practice. Quantitative velocity measurements of the flow field in a mix head have not been reported in the literature despite the extensive use of the mix head for reaction injection molding. Flow visualization and velocity measurements using a laser Doppler anemometer have been obtained for different values of geometrical parameters such as mix chamber diameter (D), distance from the nozzle inlet to the closed end of the chamber (H), and nozzle needle position (N). The ratio of the mix chamber to nozzle diameter (d) (D* = D/d) was a significant parameter affecting the flow field. The distance from the impingement point to the closed end of the chamber was found to have little effect on the observed flow field beyond the impingement area. A nozzle needle position that partially constricted the nozzle opening was found to decrease the axial distance to unidirectional flow within the mix chamber.     

Opening steel-pouring ladle slide gates without using oxygen<Superscript>1</Superscript>

In OAO Nizhnetagil Metallurgical Combine in order to open steel-pouring ladle slide gates without using oxygen starting mixes of domestic and imported production were checked instead of a quartzite starting mix.With their use the number of slide gate openings was 50%. Since this result should not be considered satisfactory, the search for suitable starting mixes continues.     

A study of relationships between state‐of‐mix,rheological properties,dynamic properties,and bound rubber content

The relationships between state‐of‐mix, rheologic properties, dynamic properties, and bound rubber content in N330 carbon black filled styrene butadiene rubber (SBR) were investigated. Shear viscosities measured from both Mooney viscometer and capillary rheometer decrease with increasing state‐of‐mix. By contrast, the stress relaxation determined from the Mooney relaxation viscometer (PR80) decreases with an increase in state‐of‐mix. In addition, glass transition temperature (T_g) is not strongly affected by a change in state‐of‐mix, whereas the magnitude of damping peak (tan δ) increases with state‐of‐mix. Bound rubber content appears to decrease as the state‐of‐mix increases. The concept of a change in an amount of immobilized rubber can be used to explain the results obtained. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1542–1548, 2000     

Use of torcrete-mix PMT-86 for intermediate ladles,study of its wear mechanism

Results are presented for a physicomechanical study of a refractory torcrete-mix grade PMT-86 produced by OOO Gruppa Magnezit. The wear intensity of a mix during operation in intermediate ladles is evaluated. Service properties are analyzed for torcrete-mix grade PMT-86 compared with imported analogs, and the high competitiveness of the mix and its attractive price and quality are demonstrated. __________ Translated from Novye Ogneupory, No. 11, pp. 7–13, November 2007.     

Structure and properties of fused periclase and periclase-chromite blocks produced from beneficiated starting materials

Conclusions Fused periclase and periclase-chromite blocks containing a high proportion of highmelting oxides of magnesium and chrome were produced from beneficiated starting materials.The structure and properties of the periclase and periclase-chromite were analyzed zonewise in the blocks. The thickness of the block zones with a high content of magnesium oxide and the yield of high-quality periclase and periclase-chromite depend on the degree of purity of the chemical composition of the starting materials.The content of magnesium oxide is highest and the proportion of contaminating oxides low in fused periclase produced from chemically beneficiated Satkin magnesite, and in the monocrystalline subzones of the blocks. An increase in the proportion of chromite in the mix results in a higher porosity and in a higher content of spinel and ferrochrome in the fused material. The properties are optimal in the case of a periclase-chromite material from a mix containing 15–20% chromite.Translated from Ogneupory, No. 3, pp. 37–44, March, 1978.     

中间包碱性干式振动料的研制与使用

以电熔镁砂或中档镁砂为主原料(骨料与基质料的质量比为65∶35),研究了有机结合剂、烧结剂以及改性剂的种类和数量对碱性干式振动料性能的影响。结果表明:分别以电熔镁砂或烧结中档镁砂为主原料,加入6%的酚醛树脂结合剂JA,2%的偏磷酸盐烧结剂SA和3%的含Al2O3的改性剂GB,研制的碱性干式振动料使用性能优良,并在多家钢厂的中间包上得到成功试用,最高使用寿命达55h,能较好地满足中间包长寿化的要求。     

基质对刚玉尖晶石质湿式喷射料流变性能的影响

以棕刚玉(5~1 mm)、板状刚玉(≤0.5 mm)、铝镁尖晶石(≤1 mm)、二氧化硅微粉(d 50=0.6μm)、氧化铝微粉(d 50=1.95μm)、纯铝酸钙水泥等为主要原料,固定物料加水量5.3%(w),采用二步法加水,制备了4组刚玉尖晶石质湿式喷射料。采用全组分流变测试仪对4组物料的流变性能进行了测试。结果表明:铝酸钙水泥的加入对物料的流变性能影响较大;提高物料中二氧化硅微粉的含量,有利于改善物料的流变性能,但仍不能适应长距离泵送施工;延缓水泥水化后,湿式喷射料的流变性能得到进一步改善,可以满足湿式喷射料的远程泵送施工。     

镁硅质防粘渣涂料的防粘渣试验及其应用

为了验证以菱镁矿、石英、黏土、氧化铬微粉及磷酸盐为原料制成的镁硅质防粘渣涂料的防粘渣性能,采用静态坩埚法(1 600℃3 h,空气气氛)对比研究了转炉钢包渣线用普通镁碳砖和VOD钢包渣线用低碳镁碳砖在涂覆该涂料前后的防粘渣性能,分析了试验后涂料的显微结构,探讨了涂料的防粘渣机制,并在宝钢进行了实际使用试验。结果表明:防粘渣涂料在熔渣与镁碳砖之间形成了明显的隔离层,起到了较好的防粘渣作用。这是由于,防粘渣涂料在1 600℃的平衡物相为MgO、M2S及MA与MK的固溶体,无液相出现,隔离了镁碳砖与熔渣的接触,不易被钢渣溶解,也不与镁碳砖发生烧结反应,还在一定程度上保护炭素不被氧化,加之其较大的体积收缩和排气反应,使其容易与粘附在其表面的熔渣一起脱落,从而起到防粘渣的作用。实际使用表明,该涂料大大减轻了钢包的粘渣程度,并延长了渣线和包口镁碳砖的使用寿命,得到了钢厂的认可。     

Unmolded refractory material produced by OOO Gruppa Magnezit for filling the steel discharge channel of steel pouring ladles

Preparation technology, assimilation of production and application of a starting mix in steel-pouring assemblies of steel-pouring ladles, operating under conditions of steel pouring into molds and in CBCM are provided. The material developed is used successfully in a number of Russian metallurgical enterprises.     

Methods for increasing the quality of medium-grain structural graphites

Different methods are considered for improving the quality of large-sized medium-grain graphites. Among these methods as very effective it is possible to separate assembly of a needle in the central part of the die making it possible to compact billets with a central hole that markedly reduces internal stresses in the material during heat treatment; use of oleic acid as a surfactant during mixing makes it possible to reduce the pitch content of the mix; elimination of the mixer method of cooling the coke-pitch mix before compaction that increases the temperature uniformity of the compacted material. __________ Translated from Novye Ogneupory, No. 9, pp. 59–62, September 2007.     

Properties of highly filled polypropylene derivative composites containing calcite and zeolite

This work aims to study the effects of high loading (total 50 wt %) of inorganic calcite, zeolite particulates, and calcite/zeolite mixture with structurally different copolymer [CoPP; poly(propylene‐co‐ethylene)] and terpolymer [TerPP; poly(propylene‐co‐ethylene‐co‐1‐butene)] systems. Melt processing is the sole mode of mixing particulates with polymer for making master batch sample throughout this work. Mechanical properties, like the modulus and yield stress, continuously increase up to a critical zeolite ratio in calcite/zeolite mix and then decrease after exceeding the critical concentration. The impact strength of the composites is not improved by replacing the calcite portion from the mix with zeolite. Morphological study was carried out for matrix–filler dispersion observation. The complex melt viscosity, increased for both systems with increasing zeolite content, indicates extra processing difficulties because of high filler volume. Burning properties and thermal stability of CoPP and TerPP composites with 50 wt % filler systems were also studied. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

α-Al2O3微粉加入量对刚玉干式捣打料性能的影响

为了提高感应炉用刚玉炉衬的服役寿命,以棕刚玉、电熔镁砂、α-Al2O3微粉为原料制备了刚玉干式捣打料,并研究了α-Al2O3微粉加入量(其质量分数为0、1%、2%和3%)对刚玉干式捣打料性能的影响。研究结果表明:经1 600℃热处理后,随着α-Al2O3微粉的增多,刚玉干式捣打料的加热永久线变化呈先减小后增大趋势,体积密度增大,显气孔率相应减小,耐压强度先减小再增大;α-Al2O3微粉加入量为2%(w)时试样的加热永久线变化相对较小,耐压强度减小到22.8 MPa。XRD和SEM分析表明:经1 600℃3 h烧后捣打料中的α-Al2O3微粉反应生成了粒状镁铝尖晶石,晶粒尺寸较小,且分布均匀,有助于捣打料致密度的提高。     

Utilization of granite sludge for production of cordierite ceramics by direct coagulation casting

In this work, an attempt to produce cordierite ceramics from granite sludge waste, talc and alumina was performed by direct coagulation casting process. To optimize the conditions for cordierite formation, three mix-compositions were firstly prepared by processing the starting materials in different conditions. The first mix was prepared by firing the mix of granite sludge, talc and alumina up to 1300 °C while the second and third mixes were fabricated by firing alumina and talc at 1300 °C or 1350 °C, respectively, then the granite sludge was added. Both batches were fired at different temperatures. According to the percentage of formed cordierite, the third mix was selected to be solidified by direct coagulation casting method followed by sintering at different temperatures. The casted cordierite was examined by thermal analysis while the sintered bodies were tested for their physical, mechanical and electrical properties. The results indicated that the pre-heating of alumina and talc at 1350 °C (third mix) enhanced the formation of cordierite and some amounts of spinel. For the casted sintered specimens, the porosity was decreased with increasing the sintering temperature. Also, there was an increase in compressive strength for the samples sintered up to 1250 °C. The dielectric constant values were varied between 4.5 and 5.89 while the dielectric loss was varied between 2 × 10^?3 and 7 × 10^?3, at room temperature.     

The rate of plasticizer uptake by suspension PVC

A microscopic technique employing image analysis was developed to measure the rate of swell of suspension PVC particles in both excess and finite amounts of plasticizer at temperatures below the crystalline melting point. The rates of plasticizer uptake derived from these swell measurements were found to be dependent upon the concentration of plasticizer and the rate of heating. A high value for the activation energy for plasticizer uptake was observed (60–100 kcal/mol) in agreement with earlier work. Each resin was also characterized by a total capacity for plasticizer (TC) which was found to be dependent on the resin type, the plasticizer type, and the maximum temperature achieved. An expression was derived for the rate of plasticizer uptake in a Brabender powder mix experiment. In this case the dry time is controlled by a single rate up to the maximum capacity for plasticizer of the resin (G_max). Values of G_max and TC were found to correlate on a one-to-one basis when measured at the same temperature. In all the cases investigated the rate of plasticizer uptake in the Brabender was found to correspond to a rate derived from image analysis swell at a plasticizer level of 0.25 cc/g. This behavior was in apparent contradiction to the concentration dependence generally observed and was demonstrated to be due to the large thermal gradients which exist in the Brabender powder mix head during the experiment. This work illustrates that Brabender powder mix times may have no relationship to dry times in a high speed mixer where heating is both even and higher temperatures are achieved.     

Experience of preparing and using water-free tap-hole mixes in OAO MMK

In the OAO MMK blast furnace plant water-free tap-hole mixes have been introduced with a carbon-containing concentrate, with a ferrosilicon nitride tap-hole product from Spetsremstroi OOO, and a Chinese product. In the first (traditional) composition instead of the coke portion there is use of a carbon-containing concentrate (CCC). Presence of silicon carbide and carbon in the CCC promotes and increase in the slag and iron resistance of the tap-hole mix. Testing a mix of the second composition has shown that in a number of parameters it is at the level of imported mixes and even surpasses them, only being inferior in specific consumption. __________ Translated from Novye Ogneupory, No. 2, pp. 18–20, February, 2007.     

New and convenient synthesis of (R)-(+)-4, 5-Dihydro-4-methyl-2(3H)-furanone and (R)-(-)-4-Bromo-3-methyl-1-O-tert-butyldimethyl-silylbutan-1-ol

A convenient partial synthesis of the lactone (+)- 10 is reported starting from the readily available methyl (S)-(+)-3-hydroxy-2-methylpropanoate (+)- 1 . Furthermore, an efficient three step route to the optically active saturated isoprene unit (-)- 13 in high yield starting from the lactone (+)- 10 is reported for the first time.     

Nylon 6 polymerization in the solid state

The postcondensation of nylon 6 in the solid state was studied. The reactions were carried out on fine powder in a fluidized bed reactor in a stream of dry nitrogen in the temperature range 110–205°C and during 1–24 h. The solid-state polymerization (SSP) did not follow melt kinetics, but was found to be limited by the diffusion of the autocatalyzing acid chain end group. Factors thought to influence SSP were studied, e.g., heat treatment, starting molecular weight, and remelting. Surprisningly, heat treatment had little effect, but the starting molecular weight had a strong effect on the reaction rate. The higher the starting molecular weight, the faster the reaction. This could be explained as a changing concentration distribution of the reactive groups in the solid state on SSP. The kinetics of the SSP had more than one region, and the rate of reaction for conversions of over 30% could be expressed as ? dc/dt = k(c/t), where k is a dimensionless constant independent of temperature with a value of 0.28. The integrated form has the form ? In(c/c_o) = k In(t/τ), where c_o is the acid end-group concentration at the start, t is the reaction time, and τ is the induction time. The value of τ is both dependent on the starting concentration c_o and the reaction temperature and has an activation energy of 105 kJ/mol.