Showing papers in "Transactions of The Indian Ceramic Society in 1964"
TL;DR: In this paper, a method for the estimation of free calcium hydroxide in set cement by D. T. G. A. has been developed, using a manually operated thermogravimetric balance.
Abstract: A method for the estimation of free calcium hydroxide in set cement by D. T. G. A. has been developed, using a manually operated thermogravimetric balance. It has been observed that loss due to dehydration of Ca(OH)2 which gives a measure of its amount can be determined from the area of the peak round 550°C after correcting for the loss at this temperature range due to other constituents of set cement by extrapolation.
10 citations
TL;DR: In this article, a general scheme has been worked out for rapid and accurate analysis of a wide variety of silicate material such as sand, felspar, clay, bauxite, glass, etc.
Abstract: A general scheme has been worked out for rapid and accurate analysis of a wide variety of silicate material such as sand, felspar, clay, bauxite, glass, etc. Silica has been estimated by a modified silico-fluoride method, Al2O3, CaO and MgO by complexometry, Fe203 and TiO2 by polarography and the alkalies by flame photometry. The analytical methods have been described in detail and the advantages and limitations of the proposed scheme have been discussed.
9 citations
TL;DR: In this article, the authors investigated six bulk samples of magnesite from Salem, Mysore, Ajmer and Almora to represent a comprehensive account of the indigenous resources, including petrography, dta and x-ray analysis.
Abstract: The investigation includes six bulk samples of magnesite from Salem, Mysore, Ajmer and Almora to represent a comprehensive account of the indigenous resources. They constitute two distinct types: cryptocrystalline and crystalline. The different deposits have been outlined comparatively in their modes of occurrence and origin. Mineralogical data include petrography, dta and x-ray analysis; they are in close correspondence with the chemical compositions of the different samples. Studies on sintering at temperatures between 1500° and 1700°C indicate that the Indian magnesites can be properly dead-burnt around 1650°C. Girechchina magnesite containing about 35% dolomite may be calcined inert at about 1550°C. The segregation of matrix, and the role of iron and other impurities during calcination have been discussed. Magnesite and chrome-magnesite refractories made from each type have been found to develop satisfactory properties, in general, and particularly with respect to refractorieness underload, and volume...
7 citations
TL;DR: Differential thermal analysis has been used for determination of surface area of china clay and bentonite samples as discussed by the authors, and it has been observed that the amount of mechanically adsorbed H2O in these samples varies linearly with the surface area.
Abstract: Differential thermal analysis has been utilised for determination of surface area of china clay and bentonite samples. It, has been observed that the amount of mechanically adsorbed H2O in kaolinite and bentonite samples varies linearly with the surface area of the samples. The amount of this adsorbed H2O has been determined from the area of the initial peak that appeared in the DTA curves of these samples.
4 citations
TL;DR: In this paper, the suitability of Indian raw materials for use as lining material for L.D vessels are described. And the choice of refractory and the advantage of dolomite over other types of materials have also been dealt with.
Abstract: The service conditions in L.D converters are dealt with and the existing refractory practice of lining these vessels is reviewed. Factors affecting, the lining wear and the role of carbon in tar bonded refractories have been discussed. The choice of refractory and the advantage of dolomite over other types of materials have also been dealt with. The suitability of Indian raw materials namely—dolomite, dolomitic magnesite and magnesite as well as suitable methods of their calcination for use as lining material for L.D vessels are described.
4 citations
TL;DR: In this paper, the occurrence of Almora magnesite and its mineralogy, sintering characteristics, crystal growth and phase changed at elevated temperatures are described and the refractory properties of the Magnesite as received as well as suitable methods of improving its properties is dealt with.
Abstract: The occurrence of Almora magnesite and its mineralogy, sintering characteristics, crystal growth and phase changed at elevated temperatures are described. The refractory properties of the magnesite as received as well as suitable methods of improving its properties has been dealt with. It is concluded that Almora magnesite could be utilised for steel plant refractories, if it is properly processed.
3 citations
TL;DR: In this article, the possibility of utilising indigenous chrome ores with varying amounts of SiO2 and iron oxide for manufacture of chrome magnesite type of refractories has been discussed.
Abstract: For manufacture of basic refractories of chrome-magnesite type use of high grade chrome ores with low SiO2, (<4%) and iron oxide (18–20% max) has been recommended. Such chrome ores are not readily available in India. As such, the possibility of utilising indigenous chrome ores with varying amounts of SiO2 and iron oxide for manufacture of chrome magnesite type of refractories has been discussed in this paper. Laboratory results indicate that chrome ores with even 8 to 10% SiO2 could be used and chrome concentrate with 7% SiO2 may be utilised. The ratio of chrome and magnesite varies with the quality of chrome ores used. Proper adjustment of grain sizes is an important factor.
3 citations
TL;DR: In this paper, the influence of soaking time on the densification of the compacts of thoria has been studied at sintering temperatures of 1300° to 1550° C.
Abstract: The influence of soaking time on the densification of the compacts of thoria has been studied at sintering temperatures of 1300° to 1550° C. Same thoria powders used in the earlier investigation were used for this study1; they were prepared by thermal decomposition of thorium compounds. Increase in the soaking time resulted in significant drop in density during a specific period for each of the powders.The maximum density attained, the extent of drop in density and the period at which it occurs are related to the optimum sintering temperature of the thoria powder. No such changes in density were noticed during vacuum sintering of the same powders.This change in densification due to varying sintering conditions has been explained to be due to entrapment of porosity during heating to the sintering temperature; the pressure exerted by the gases in the pores on the viscous matrix, results in an enhancement of pore 'size and lowering of bulk density. Gradual elimination of gases in pores by diffusion results i...
2 citations
TL;DR: Tar impregnation of nozzles from Indian sources was undertaken to see the possibility of using them as substitute for imported bloating type of Nozzles as discussed by the authors, and the experimental details of the tar impregnated nozzle technique has been described.
Abstract: Tar impregnation of nozzles from Indian sources was undertaken to see the possibility of using them as substitute for imported bloating type of nozzles. The properties of the nozzles improved after tar impregnation. The experimental details of the tar impregnation technique has been described. The service performances of the tar impregnated nozzles have been given and reasons discussed. The possible fields of application of the technique have also been indicated.
2 citations
TL;DR: A decolourising process, developed at the Central Glass & Ceramic Research Institute, considerably improves the brightness of the clay, in some instances upto 15-20 units as discussed by the authors.
Abstract: The principles involved in the washing of china days and the various' stages of operation are discussed. The improvements that can be effected by electrolytes, in the quality and the quantity of the recovered fraction are shown. The necessity of including a ‘demagnetising’ step is stressed. A decolourising process, developed at the Central Glass & Ceramic Research Institute, considerably improves the brightness of the clay, in some instances upto 15–20 units. This process can be incorporated in the regular operations of a washing, plant. © 1964 Taylor & Francis Group, LLC.
2 citations
TL;DR: The morphology of the kaolinite mineral in domestic refractory clays varies from well developed hexagonal platelets to poorly developed or rounded off crystals as discussed by the authors, and is associated with varying amounts of free quartz and minor quantities of illite as well as feldspar in some cases.
Abstract: Mineralogical constitution of ten domestic refractory clays and the morphological characteristics of the principal clay mineral present in them have been studied by differential thermal analysis, X-ray powder diffraction and electron microscopic techniques.Kaolinite is the principal clay mineral in all these clays and is associated with varying amounts of free quartz and minor quantities of illite as well as feldspar in some cases. The morphology of the kaolinite mineral in these clays varies from well developed hexagonal platelets to poorly developed or rounded off crystals.
TL;DR: In this article, the compressive strength of the lime-slag cements prepared from slags of composition in the system CaO-Al2O3-SiO2 reported in Part I of the paper have been correlated statistically with relevant factors, such as degree of hydration of slags, amount of slag per briquette and fractional volume of the test briquettes occupied by lime, slag and sand.
Abstract: Compressive strengths of the lime-slag cements prepared from slags of composition in the system CaO-Al2O3-SiO2 reported in Part I of the paper have been correlated statistically with relevant factors, such as degree of hydration of slags, amount of slag per briquette and fractional volume of the test briquettes occupied by lime, slag and sand. Degree of hydration and amount of slag per briquette were combined into one by multiplying them, the product being a measure of the amount of hydrated material present in a test piece. The final relation was found as where C = compressive strength lb/in.2 Hm = product of degree of hydration of slag and amount of slag/briquette P = percent volume packed.
TL;DR: In this paper, a systematic study was made of the dielectric properties of different types of stained mica from Bihar and it was concluded that an appreciable portion of the so-called inferior grades of mica were suitable for use in condensers.
Abstract: With a view to properly evaluate the so-called inferior grades of mica a systematic study was made of the dielectric properties of different types of stained mica from Bihar. Stains and inclusions were found to have very little effect upon resistivity and dielectric strength and from the results it is apparent that all the varieties of stained mica are equilly suitable for the purpose of normal insulation up to a temperature of 400°C. Even though power factor was found to increase with the amount of air and mineral inclusions still it could be concluded that an appreciable portion of the so-called inferior grades of mica were suitable for use in condensers. © 1964 Taylor & Francis Group, LLC.
TL;DR: In this article, a few glassy slags in the system, CaO-Al2O3-SiO2 were prepared having a fixed SiO2/Al 2O3 ratio of about 1.15 and different proportions of CaO in the range of 35-50 per cent by weight.
Abstract: A few glassy slags in the system, CaO-Al2O3-SiO2 were prepared having a fixed SiO2/Al2O3 ratio of about 1.15 and different proportions of CaO in the range of 35–50 per cent by weight. The hydraulic properties of the slag powders in admixture with different proportions of hydrated lime were studied. The hydraulicity of the slags increased with increase in the proportion of CaO in their chemical compositions and also with the increase of lime in the mixture. The amount of lime necessary for the development of maximum strength was found to decrease with increasing CaO content of the slag.
TL;DR: The importance of casting pit refractories and their properties have been discussed in this article, where a short review of literature has been made, and the possibility of manufacturing the pyroplastic type of casting from indigenous low alumina plastic clay with addition of pyrophyllite or talc has been indicated.
Abstract: The importance of casting pit refractories and their properties have been discussed. A short review of literature has been made. Two types of casting pit refractories are generally used—one with comparatively high refractoriness and the other with low refractoriness and bloating or pyroplastic characteristics. The latter type, though preferred, is not made in the country. The possibility of manufacturing the pyroplastic type of casting, pit refractories from indigenous low alumina plastic clay with addition of pyrophyllite or talc has been indicated.
TL;DR: In this paper, the advantages of the Almora Magnesite deposits can be considerably enhanced by exploiting the deposits in an integrated manner, such an exploitation will call for a considerable capital outlay.
Abstract: Contrary to popular belief, the magnesite deposits prospected by the Indian Bureau of Mines in the Almora region have certain natural and sizeable economic advantages over the deposits of the Salem-Mysore region. These advantages of the Almora deposits can be considerably enhanced by exploiting the deposits in an integrated manner. Such an exploitation will call for a considerable capital outlay. The alternative sources discussed include: (i) the talc-magnesite rock 8 miles south of Tatanagar Railway Station, (ii) MgO from magnesium salts recovered or likely to be recovered in course of the manufacture of common salt and (iii) the occurrences of economic deposits which may be located in the eastern Himalayas through a specific search made for the purpose.
TL;DR: In this paper, the Taylor & Francis Group investigated the use of different types of bauxites and chromites to prepare chrome-alumina refractories for steel pouring ladles and regenerators of open hearth furnaces.
Abstract: Investigations were carried out with different types of bauxites and chromites to prepare chrome-alumina refractories. Raw materials mixed in suitable proportions to give 10–12 percent Cr2O3 in the product were calcined at 1600° and then graded. Bricks formed under pressure and fired to 1600° indicate promising results but high porosity. Lime addition (2–3%) in the mixes appreciably reduces porosity but slightly affects the refractoriness. Chrome ores containing about 5 percent silica is suitable for the purpose. Chrome-alumina refractories thus made possess desirable properties and their use in steel pouring ladles and regenerators of open hearth furnaces may be considered. © 1964 Taylor & Francis Group, LLC.
TL;DR: The role of National Metallurgical Laboratory in catering to the needs of the industry has been mentioned briefly in this article, where the present consumption rate and estimate for the future as well as projected targets for iron and steel industry upto the end of the fourth five year plan, the refractory requirements and the course of action necessary to meet the demand have been suggested.
Abstract: The growth of steel plant refractories which follows closely the iron and steel industry has been traced for the past one and half decades and the gradual fall in refractory consumption per ton of ingot steel produced in India during the same period has been indicated. Based on the present consumption rate and estimate for the future as well as the projected targets for iron and steel industry upto the end of the fourth five year plan, the refractory requirements and the course of action necessary to meet the demand have been suggested. The role of National Metallurgical Laboratory in catering to the needs of the industry has been mentioned briefly.
TL;DR: In this article, the application of clay graphite products in the handling of steel is reviewed and the properties of certain products developed during the course of the above work are given and the steps taken to utilise the results on a commercial scale are described.
Abstract: The application of clay graphite products in the handling of steel is reviewed. Availability of raw materials in the country and work done at National Metallurgical Laboratory on their suitability and improvement have been discussed. Finally the properties of certain products developed during the course of the above work are given and the steps taken to utilise the results on a commercial scale are described.
TL;DR: In this article, the utility of polarization microscopy in different branches of glass and ceramic has been discussed, and the role of impurities has been described, with a few examples.
Abstract: The utility of polarization microscopy in different branches of glass and ceramic has been discussed. Beside identification of different constituents, and evaluation of the raw materials, petrographic studies may help in explaining anomalous observations and in correlating properties. The role of impurities has been discussed quoting a few examples. In the study of stones in glass, petrography is extended from identification to locating the source of the defect. It may ensure a control over quality during production as also over the degree of firing of some ceramic materials.
TL;DR: In this paper, the authors have reviewed the positions with respect to quartzite, sillimanite, kyanite and other raw materials in terms of their suitability for refractory materials.
Abstract: The refractory materials form a major portion of the developing minerals industry in India. The requirement of refractories and related raw materials are anticipated to double up during the fourth plan period. For basic refractories, Indian resources of magnesite, dolomite and the dunite type of rocks are adequate; the resources of refractory grade chrome ore with low SiOs and Fe2O3 are known to be limited. Detailed prospecting around Orissa, Maharashtra (Bhandara) and other localities, as also utilisation of low grade ores, on beneficiation, are likely to improve the situation. Although, the resources of bauxite in India are vast, bulk of them, excepting those of Saurashtra and few other deposits, are not suitable for refractories in view of high Fe2O3 and TiO2 contents. Detailed information on high aluminious and plastic clays are lacking. The positions with respect to quartzite, sillimanite, kyanite and other raw materials are satisfactory and have been reviewed in outline. Timely publication of data, sufficient for evaluating the quality and economy of the resources will facilitate planning and exploitation of the deposits—new and old. © 1964 Taylor & Francis Group, LLC.
TL;DR: In this paper, the origin of non-metallic inclusions in railway wheel ingots and rolled railway wheels, produced at Durgapur Steel Plant, has been investigated and it has been shown from the X-ray studies that majority of the inclusions originate from refractory ware.
Abstract: Investigations have been carried out to trace out the origin of non-metallic inclusions in railway wheel ingots and rolled railway wheels, produced at Durgapur Steel Plant. It has been shown from the X-ray studies that majority of the inclusions originate from refractory ware. A laboratory survey has been made on the properties of casting pit ware used in the plant, from four suppliers. In general, properties are not satisfactory as far as workmanship, coarse grog size in the brick and variation in apparent properties arc concerned.