橡胶籽油还原作用下铜渣的贫化

针对铜渣贫化过程碳排放问题,以橡胶籽油取代柴油作为铜渣贫化的还原剂,研究铜渣贫化过程中的热力学,分析橡胶籽油贫化铜渣机理。在不同温度和时间条件下进行喷吹橡胶籽油贫化实验,分析铜渣磁性铁含量和粘度的变化,用XRD和SEM对贫化后炉渣进行分析。结果表明,喷吹还原过程中主要还原剂是裂解产生的碳单质、H2和CO。贫化过程中磁性铁被橡胶籽油在高温下的裂解产物(H2, CO, C)还原成FeO,与渣中的SiO2结合生成铁橄榄石(Fe2SiO4);随贫化温度升高,相同喷吹时间内铜渣的磁性铁含量和粘度逐渐降低,使渣中的Cu相互碰撞聚集,最终沉降到坩埚底部。随贫化进行铜渣中的铁橄榄石相增多,磁性铁相减少。在坩埚底部聚集的铜颗粒粒度由1 cm增至3 cm,铜回收率达86%。     

The Effect of Reducing and Oxidizing Gases and Molten Slag and Alkalis on the Properties and Resistance of Nitride-Based Refractory Materials

Silicon carbide refractory materials and specimens of silicon nitride and silicon oxynitride are tested under high-temperature attack from reducing (H₂ and CO) and oxidizing gases (O₂, air) and from molten slag, alkalis, and iron. It is shown that nitride-based refractory materials are prone to change their properties, structure, and resistance when exposed to molten slag, iron, and alkalis. Silicon oxynitride and silicon nitride resist attack from carbon monoxide and alkali and provide protection to silicon carbide used as the refractory lining for blast furnaces.     

Schungite for improving the durability of the refractory lining in blast furnace runners

A technology for manufacturing refractory ramming mixtures for the runners of blast furnaces is proposed based on the use of schungite in place of the conventional coke. The resistance of the lining to attack by molten metal and slag and its service life improved significantly using silicon carbide produced from schungite. __________ Translated from Novye Ogneupory, No. 5, pp. 29–31, May, 2006.     

Influence of Additives on Slag Resistance of Al2O3-SiO2-SiC-C Refractory Bond Phases under Reducing Atmosphere

The microstructures of Al₂O₃–SiO₂–SiC–C refractory matrices with aluminum, silicon, Si₃N₄, BN, B₂O₃, and B₄C additives are characterized before and after a crucible slag test, and the phases present are compared to those expected at thermodynamic equilibrium. The carbon content dominates the resistance to CaO–MgO–Al₂O₃–SiO₂ slag penetration, while the viscosity of liquid phases present has a significant influence when the matrix carbon contents are similar. Silicon and Si₃N₄ additives reduce slag penetration resistance because of indirect oxidation of carbon to form SiC. B₄C, in particular, and B₂O₃ also reduce slag penetration resistance because of formation of a more fluid boron-containing liquid, while aluminum and BN addition have no significant effect. Carbon and BN hardly react with the slag, while SiC partially reacts with it, leading to deposition of carbon as a dense layer. Corundum present in the refractories also readily dissolves in the slag. Microstructurally, slag penetration resistance is associated with the dense carbon layer located at the slag-refractory interface.     

Investigation of Taimyrsk graphites for producing periclase-carbon ladle refractories

Conclusions The investigations showed that Taimyrsk graphite corresponds in chemical composition to foundry and crucible graphite.The content of crystalline graphite equals 13.0–26.3%. The characteristics of periclase carbon goods based on foundry and Taimyrsk graphites correspond to the demands placed on ladle refractories. The wear factors of these products in the slag belt of the lining of 350-tonne steel ladles are on practically the same level.Taimyrsk graphites may be used for the production of periclase-carbon ladle refractories in place of crucible or foundry graphite.L. N. Kurlyandskaya (Urals Geology Planning Association) and L. Ya. Osipova (All-Union Institute of Refractories) took part in this research.Translated from Ogneupory, No. 1, pp. 15–17, January, 1991.     

Al2O3-ZrN-Sialon-C复相耐火材料抗渣侵性能研究

以板状刚玉、石墨、α-Al2O3、金属铝粉、单质硅粉为主要原料,ZrN-Sialon复相粉体为添加剂,采用酚醛树脂结合制备了Al2O3-ZrN-Sialon-C复相耐火材料.采用静态坩埚法研究了ZrN-Sialon复相粉体加入量对材料抗渣侵蚀性能的影响,借助SEM与EDS面扫描对渣蚀后材料的结构和成份进行分析,并探讨了Al2O3-ZrN-Sialon-C复相耐火材料的抗渣侵蚀机理.结果表明:ZrN-Sialon复相粉体加入量为9wt％时,材料表现突出的抗钢渣侵蚀性能.研究表明材料中Sialon氧化后生成的SiO2能形成致密的氧化保护层,同时ZrN氧化后形成的ZrO2有利于提高抗钢渣的浸润,阻止钢渣的渗透与侵蚀.分析认为Al2O3-ZrN-Sialon-C复相耐火材料的钢渣侵蚀机理为氧化-熔蚀-渗透.     

高炉用新型自结合碳化硅砖性能研究

借助XRD、SEM等技术,对新型自结合碳化硅砖的抗碱性、抗渣性和抗热震性等高炉耐火材料的关键使用性能进行了研究,并与Si3N4结合碳化硅高炉砖进行了对比。结果表明:这种新型自结合碳化硅砖热导率高,力学性能好,抗碱性、抗渣性和抗热震性优良,预计用作高炉内衬具有良好的应用前景。     

On a Mechanism of Wear of the Periclase-Carbon Lining for Oxygen Converters

Effects associated with the capillary impregnation of the refractory materials with melted slag, the chemical interaction of graphite carbon with slag, and the dissolution of periclase in slag are considered. The time needed for melted slag to penetrate to the hot-layer depth of the refractory lining is a matter of several seconds. The carbon component on its contact with melted slag is reduced with FeO to yield CO. The partial pressure of carbon monoxide p _CO is calculated as a function of temperature (1500 – 1700°C) and FeO activity (0.1 – 0.5) in melted slag. The pressure p _CO is shown to exceed the capillary pressure of melted slag in pores, which prevents the easy penetration (because of the CO bubbles formed) of the slag into the periclase-carbon lining. The lining-wear effects due to the MgO concentration in the slag and to the size of periclase crystals are considered.     

Effect of carbon and silicon carbide on the properties of carboxylated refractories

The interrelation between the content of carbon and silicon carbide and the properties of carboxylated refractories (porosity, mechanical strength, heat resistance, resistance to the action of blast-furnace slag) is studied. Dependences of the properties of carboxylated refractories on their material composition are plotted. __________ Translated from Novye Ogneupory, No. 4, pp. 35–37, April, 2007.     

Experience with MgO-bearing materials for raising the stability of converter linings

Accumulated experience shows that one can increase the resistance of converter linings in various ways, with the largest effect from the use of self-decomposing magnesium materials in the form of granules or briquettes. The advantage of these materials comes from the presence of hydrated or carbonate components producing explosive decomposition on entry into the converter slag, with the slag rapidly saturated in MgO, with an increase in viscosity and the formation of a stable lining. __________ Translated from Novye Ogneupory, No. 4, pp. 3–5, March, 2007.     

Slag Resistance of Refractories for Direct Reduction of Laterite Nickel Ores in Rotary Kilns

Aiming at prolonging the service life of refractories for direct reduction of laterite nickel ores in rotary kilns, the slag resistance of ten materials(corundum bricks, chrome corundum bricks, silicon nitride bonded silicon carbide bricks, high alumina silicon carbide bricks, high alumina bricks, magnesia chrome bricks, magnesium aluminate spinel bricks, spinel chrome corundum bricks, chrome corundum castables and magnesia alumina chrome composite spinel bricks) was evaluated by rotary slag tests, which simulate the service conditions in rotary kilns. The corroded residual bricks were analyzed by SEM and EDS. The results show that the magnesia alumina chrome composite spinel brick possesses the advantages of magnesium aluminate spinel bricks and chrome corundum bricks; MgO-rich spinel can absorb the penetrated ferric oxide, and forms a dense zeylanite layer, which prevents the penetration of the molten laterite nickel ores; therefore, it is an ideal lining of rotary kilns for direct reduction of laterite nickel ores.     

Use of unfired periclase-carbon refractories in parts of linings of 350-ton steel-teeming ladles

Workers of the Azovstal’Company have established the causes of the decrease in the endurance of slag-line areas of linings of 350-ton steel-teeming ladles. In 1995–1996 they conducted industrial tests and introduced a process for lining the slag areas of 350-ton teeming ladles with unfired periclase-carbon refractories. The mean service life of a lining of a 350-ton teeming ladle with a slag line made of periclase-carbon refractories amounts to 23 heats on the average without hot repairs of the slag line during the campaign. The wear of the periclase-carbon lining in the slag line is 3.6–4.3 mm per heat. The specific consumption of refractories and materials for a lining has been decreased by 0.6–0.8 kg per ton of converter steel. Such an operating capacity for the periclase-carbon refractories in slag lines is provided by the composition and structure of the refractories, which possess a high heat resistance and resist the effect of the molten metal and slag. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 2, pp. 37–39, February, 1998.     

旋风炉SiC质炉衬损毁机理研究

热电厂旋风炉ＳｉＣ炉衬，由于受液态渣的侵蚀，在短期内损毁。本文研究了液态渣的物相、渣村的相互关系，认为ＳｉＣ炉衬的侵蚀机理：一方面由于增钙，液态渣变稀，渣中多钙、铝而少硅，对炉衬的渗透力强，能夺取ＳｉＣ中的硅，造成化学侵蚀；另一方面是由于旋风燃烧的作用，液态渣对炉衬的机械侵蚀。该研究结果为研制新炉衬提供了依据。     

Testing ladle brick made by various factories

Conclusions The resistance of linings in steel-casting ladles depends on the working conditions and the construction of the lining, the quality of the brick laying during repairs of the working layer, and the resistance of the ladle brick. The greatest effect on the wear of the lining in ladles is exerted by the following working conditions: chemical composition of the slag, temperature of the metal being cast, the dwell time of metal and slag in the ladle during one casting, the height of the slag layer in the ladle, the thickness of the lining in each belt of the structure. The quality of the structure in the ladles is mainly determined by the size of the joints, the care with which they are filled with mortar, uniformity of drying and warming-up of the ladles before filling them with metal.The resistance of the ladle brick depends mainly on the apparent porosity and nature of the pores and the concentration of fluxes and mullite in the brick.The highest resistance in service was shown by Zaporozh'e ladle brick made from Polozhe kaolin and having the lowest apparent porosity. The concentration of iron oxides in the brick was moderate, and on average equalled 1.39%.In terms of falling resistance the ladle brick of the remaining concerns can be placed in the following order: Chasov-Yar, Semiluks, Bogdanovich, Magnitogorsk, and Borovich.In order to increase the resistance of steel casting ladle linings it is necessary to increase the resistance of the ladle brick by reducing the apparent porosity, using raw materials with low concentrations of fluxes and improving the firing in order to obtain the maximum conditions of the ladle, reducing to a minimum the quantity of slag and reducing the casting time; to use a more rational thickness for laying the ladles over the courses, taking into account better use of their capacity.Translated from Ogneupory, No.5, pp. 27–32, May, 1970.     

Wear of magnesia spinel refractories in portion vacuum-processing steel plant

Conclusions The processes of wear in the lining of vacuum chambers of outdoor-furnace vacuum-treatment plants (UPVS) are due to the simultaneous action of high temperatures, deep vacuum, gaseous medium, molten metal, and slag. The corrosion and erosion of aggressive melts of slag and metal are the decisive forms of wear.Laboratory investigations established the relationship between slag resistance in vacuum and the ratio of corrosive and erosive constituents in the wear of different magnesia-spinel refractories and their phase composition, structure, and properties.Refractories obtained from fused periclase-chromite material with a low content of fusible silicates showed that in laboratory vacuum equipment and during service in the linings of the vaccum chamber of industrial plant they have higher slag resistance and lower wear than refractories based on sintered magnesite, spinel, and chromite ores.Translated from Ogneupory, No. 3, pp. 14–21, March, 1980.     

Development of a lining made from Karelian quartzites for crucible induction furnaces

Factors are considered that increase the service life of a lining for a crucible induction furnace. Results are provided for laboratory studies and industrial tests of Karelian quartzites of Jotnian age of the Shokshinsk formation and Jatulian age of the Metchang’yarvinsk formation. The effect of impurities is quartzites on crucible induction furnace lining wear resistance is studied. Brief characteristics of quartzites are provided. The possibility is established of using waste materials from quarry production of Shokshinsk quartzites for preparing quartzite mixes.     

Cr7C3: A potential antioxidant for low carbon MgO–C refractories

Magnesia carbon (MgO–C) refractory, one of the most commonly used refractories in the steelmaking system, relies on graphite to improve the thermal shock resistance and slag corrosion resistance. The oxidation of graphite carbon in a MgO–C brick usually leads to the destruction of the carbon network in the brick, which causes the structure of the brick to become loose and easily eroded. At present, metal powders, carbides, and borides are used as antioxidants to prevent the oxidation of carbon in MgO–C bricks. The metal carbide Cr₇C₃ can be prepared from aluminum chromium slag through a simple synthetic process and at a low cost. In this work, we investigated the oxidation resistance of low carbon MgO–C refractories with different amounts of Cr₇C₃ powder (1, 2, 3, and 4 wt%). The refractories with 3 wt% Cr₇C₃ powder showed optimal resistance to oxidation. The microstructure indicated that oxygen reacts with Cr₇C₃ preferentially over carbon to form chromium oxide and magnesium chromium spinel, blocking the pores and hindering oxygen diffusion. Carbon arising from the reduction of carbon monoxide by Cr₇C₃ can act as a supplementary carbon source. The better oxidation resistance also contributed to the improvements in slag corrosion and thermal shock resistance of the refractories.     

高炉中部内衬耐火材料的选择

在实验室条件下进行了粘土砖、高铝砖、氮化硅结合及赛隆结合的碳化硅砖抗初渣又碱金属侵蚀的试验研究。结果表明：赛隆结合的碳化硅砖具有优良的抗侵蚀能力，推荐用作高炉中部内衬材料。     

Destructive processes of periclase grains in fettling back walls of open-hearth furnaces

Conclusions During the first melting the working layer of the lining in the back wall is impregnated with iron oxides, calcium, silicon, etc. which leads to a reduction in the content of MgO in the working layer to 25%, and the formation of up to 40% fusible silicates in the bond. This leads to solution of the periclase grains with the formation of weak structures (an island-like character). The refractoriness of the working surface of the lining in the back wall drops to 1500–1550°. The split-up grains of periclase are easily melted and eroded by the slag and metal and pass into the slag melts.The life of the lining of the back wall increases with the use of fine-grained magnesite powder moistened by 3–4% water. With this the dust removal into the checkers of the regenerators is reduced.The following workers took part in the work. G. T. Til'k, N. I. Antropov, G. V. Chernoskutov, R. V. Krivonosova, M. A. Levanto, A. B. Dokshitskii, Yu. P. Gilev, V. G. Chekhonin, V.I. Dresvyankin.     

Quartzites for crucibles and methods of lining crucible induction furnaces (Review)

Conclusions With observation of the requirements of chemical and grain-size compositions, progressive methods of lining work, and sintering of the crucible, domestic quartzites provide a long lining life of induction crucible furnaces in melting of iron and sufficient life in melting of carbon steel.Translated from Ogneupory, No. 6, pp. 48–52, June, 1985.