Wetting of aluminosilicate refractories with cast iron

Pitak, N. V.; Fedoruk, R. M.; Shulyak, R. S.; Khmelenko, T. P.

doi:10.1007/bf01280941

Cited by 6 publications

(8 citation statements)

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“…After reroasting under the same conditions, ShKP chamotte from Polgi kaolin exhibits contrary changes. The apparent density increases from 2.44 to 2.52 g/cm 3 and the shrinkage is enhanced to 3.8% [2]. roasting losses AP (4-6), and density p (7-9) of mullite--corandum briquet (79% A1203) vs temperature t: 1, 4, 7) roasting in air; 2, 5, 8) roasting in a fine coke charge; 3, 6, 9) in hydrogen.…”

Section: ~ 4 1 2omentioning

confidence: 95%

“…4 4), and roasting losses A P (5, 6) of specimens of Novoselki kaolin vs roasting temperature t in air (1,3,5) and in a fine coke charge (2,4,6). Fig.…”

Section: ~ 4 1 2omentioning

confidence: 99%

“…4. Content G of A120~ (1,2) and SiC) z (3,4) in insoluble residues of ohamottes obtained by roasting at different temperatures t in air (1, 3) and a fine coke charge (2,4). Figure 1 gives the results of an investigation of the properties of chamotte obtained by roasting Novoselki kaolin with different amounts of added quartz sand of natural grain size and of hydrargillite.…”

Section: ~ 4 1 2omentioning

confidence: 99%

“…The literature gives information on the elastic constants of certain refractories [1][2][3][4][5] and on the dependence of the elastic modulus of refractory materials on other indices [6][7][8][9][10][11], but such data are not given for unroasted siliceous materials. …”

Section: Literature Citedmentioning

confidence: 99%

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Changes in the properties of aluminosilicate refractories during roasting and service

Pitak

1979

Refractories

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The properties of aluminosilicate refractories and their service life depend on the composition and content of crystalline, amorphous (liquid), and gaseous phases. The principal crystalline phase of aluminosilicate refractories (chamotte and high-alumina refractories) is mullite. Above the composition of mullite, the refractories contain corundum; below the muilite composition, cristobalite and quartz are present. A second phase in the cold refractory is a vitreous substance; in the hot refractory, it is a melt, a third phase is air or a mixture of gases of complex composition; the gas phase composition may differ significantly in the open and closed pores. During roasting and service, each phase exerts an influence on the properties of the refractories and must be taken into account when developing heat-resistant linings.Much attention has been paid to the formation and change in the crystalline phases of refractories, but somewhat less to the vitreous substance, and even less to the role of the gas phase.This communication gives results of investigations, obtained during roasting of kaolin and kaolin--alumina briquets and aluminosilicate refractories in various gaseous media, and the calculated changes in the Gibbs free energies (AZ) over a wide range of partial pressures of oxygen for the reactions of formation of silica, silicon monoxide, and mullite.The quality of aluminosilicate refractories largely depends on the properties of chamotte. The principal requirement for the preparation of high-grade chamotte is purity of the clays, kaolins, and other initial materials. But the chemical composition of clays and kaolins cannot be the principal criterion for assessing the quality of the initial material. In a number of cases [1], chamotte and artifacts with different properties are obtained from kaolins of the same composition, roasted under the same conditions. This is due to the fact that certain kaolin varieties contain not only kaolinite but also admixtures of quartz sand and hydrargillite. In such cases the compositions of the initial material are equivalent, but the properties of the artifacts obtained differ. ~, 4 1 2O ~2 762, O 1Z

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Section: ~ 4 1 2omentioning

confidence: 95%

“…4 4), and roasting losses A P (5, 6) of specimens of Novoselki kaolin vs roasting temperature t in air (1,3,5) and in a fine coke charge (2,4,6). Fig.…”

Section: ~ 4 1 2omentioning

confidence: 99%

Section: ~ 4 1 2omentioning

confidence: 99%

Section: Literature Citedmentioning

confidence: 99%

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Changes in the properties of aluminosilicate refractories during roasting and service

Pitak

1979

Refractories

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“…Even a small amount of quartz sand in the kaolin increases the water absorption and porosity of the chamotte [5, 6]. Among the other impurities which produce an adverse affect on the quality of the chamotte are sulfur compounds of iron which during roasting in a rotary kiln do not dissociate completely, the result being that the refractory product undergoes bloating during firing; and titanium compounds which form a significant proportion of the melt and reduce the service durability of the product [7, p. 210].…”

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Beneficiation of secondary Novoselitsy kaolin

1978

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The secondary kaolins of the Novoselitsy deposits are used mainly for the production of dense chamotte brick for the high-temperature part of blast-furnace stacks [I, 2]. The special-grade Novoselitsy kaolin is the best raw material of Soviet origin for the production of the high-quality refractories of porosity below 12% for the 5000-m ~ blast furnace at the Krivoi Rog Metallurgical Plant [3,4].The high nonhomogeneity of the grain size, mineral, and chemical compositions of the Novoselitsy kaolins are the main source of the technological difficulties encountered in the roasting of the kaolin to chamotte and the manufacture of high-performance refractory products. Even a small amount of quartz sand in the kaolin increases the water absorption and porosity of the chamotte [5, 6]. Among the other impurities which produce an adverse affect on the quality of the chamotte are sulfur compounds of iron which during roasting in a rotary kiln do not dissociate completely, the result being that the refractory product undergoes bloating during firing; and titanium compounds which form a significant proportion of the melt and reduce the service durability of the product [7, p. 210].The most critical refractories are produced from the special grade KN--O of Novoselitsy kaolin. The yield of this grade in the extraction operations is falling constantly so that the Ural Institute of Beneficiation and the Mechanical Processing of Minerals initiated research in a benefieiation technology for low-grade Novoselitsy kaolin with a view to obtaining a concentrate finer than 0.056 mm containing at least 43% A1203 and not over 1.3% Fe203 (on the calcined substance).The sample of kaolin of grade KN-2 conformed to TU 14-8-160--75 and contained 34.48% A1203 (in terms of the dry substance), 49.18% SiO2, 1.30% Fe20~, 1.46% TiO2, 0.12% K~O + Na20, 0.20% CaO, and 0.06% MgO; calcination loss 12.97%. The mineral composition of the sample was as follows: 76.5% kaolinite, 9.5% quartz, and 11% hydromica with the accessory minerals marcasite (0.7%), rutile (0.8%), iron hydroxides (0.2%), and a carbonlike substance (0.7%).A fractlonwise chemical analysis of the Novoselitsy kaolin (Table i) showed that in terms of the clay content the fractions finer than 2 ~ are the purest:. The fractions coarser than 2 ~ contain more Fe20~ and free quartz; the high iron oxide content is attributable to the presence of marcasite.An analysis of the separation curves (Fig. i) suggested that Novoselltsy kaolin can be beneficiated by separating it into grain sizes. For a beneficiated kaolin of grade KN-O conraining at least 43% Ala03 for the limiting grain size is 100-200 ~. A smaller grain size of separation offers no advantages because it gives a significantly lower yield of concentrate and less extracted A1203 although the AI~03 content is then slightly higher and the Fe20~ content lower.An investigation was carried out of the wet gravitational beneficia~ion of the kaolin in high-density suspensions [8]. The separation of high-concentration clay suspensions into graln-...

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Refractories for lining large-capacity blast furnaces

Pitak

Starshinov

1982

Refractories

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Refractories are an important design material in the construction of blast furnaces.In analyzing the resistance of refractories in the lining of blast furnaces it is necessary to take into account not only the quality of the articles but also the design features of the lining and its exploitational conditions.In such an approach we can discover the objective factors causing the destruction of the lining and can select the best ~ays of improving its resistance.In the current Five-Year Period and up to 1990, the construction of blast furnaces of a volume of 3200 to 5000 m 3 or more is planned.It is well kno~n that the life of the linings of different sections of the blast furnaces varies over wide limits.The life of the linings of the shaft and bosh parallel is between 2 and 12.5 years with an average of 5.2-5.4 years, while the life of the refractories in the hearth and hearth bottom is 5 to 22 years with an average of 14-17 years.Therefore, in the next few years it is necessary to concentrate attention on prolonging the life of the linings of those sections of the furnace which show intensive damage.In the case of the linings of the shaft and bosh parallel, dense and high-density chamotte refractories are normally used.In some cases the bosh, bosh parallel, and shaft are lined with silicon carbide refractories in nitride and oxynitride binders, mullite, corundum, corundum--chromite, spinel, semigraphite, and other products.During service the most rapidly damaged sections of the refractory lining of blast furnaces are the cooled regions of the shaft, bosh parallels, and bosh, the tuyere zone, the regions of tile iron notches, and the upper part of the hearth bottom.The uncooled region of the shaft in most cases is lined with a compacted chamotte refractory with a porosity <17%.This part of the lining, of course, is little corroded and is not always replaced during the major overhaul of category II blast furnaces.The cooled region of the shaft, bosh parallel, and boshes are lined with dense chamotte refractories with a mass fraction of 39-42% A1203.The most intense damage to the refractory lining of the shaft is found in the region of the lower rows of coolers. Therefore in the lower part of the shaft, bcsh parallel, and boshes, dense kaolin articles with a porosity of 8-12% are used; the latter are produced at the Chasov-Yarsk Refractory Combine.Blast furnaces are operated over practically the whole period with the same fittings in the bosh parallel, the cooled part of the shaft, and the boshes.The tuyere zone is lined with chamotte or sometimes with mullite or mullite--corundum refractories.To line the well, carbonaceous blocks mainly are used, and in the openings of the iron notches, dense chamotte, mullite, or mullite--alumina refractories and sometimes carbonaceous.The upper part of the hearth bottom is made in the form of a combined lining of carbonaceous m~d mullite blocks, or only carbonaceous blocks.The damage to the lining in this region of the furnace occurs because a new surface appears on the blocks as...

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Wetting of aluminosilicate refractories with cast iron

Cited by 6 publications

References 1 publication

Changes in the properties of aluminosilicate refractories during roasting and service

Changes in the properties of aluminosilicate refractories during roasting and service

Beneficiation of secondary Novoselitsy kaolin

Refractories for lining large-capacity blast furnaces

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