DEVELOPMENT OF DINAS REFRACTORY MASS BASED ON LOCAL RESOURCES OF UZBEKISTAN

Transcription

1 Journal Azizjon of Chemical A. Eminov, Technology Zulayho R. and Kadyrova, Metallurgy, Raisa 52, I. 1, Abdullaeva 2017, DEVELOPMENT OF DINAS REFRACTORY MASS BASED ON LOCAL RESOURCES OF UZBEKISTAN Azizjon A. Eminov, Zulayho R. Kadyrova, Raisa I. Abdullaeva Institute of General and Inorganic Chemistry Academy of Sciences of Uzbekistan 77a Mirzo-Ulugbek st., , Tashkent Uzbekistan Received 18 February 2016 Accepted 10 October 2016 ABSTRACT А study focused on the development of dinas refractory ramming masses on the basis of local raw resources of Uzbekistan is reported. The effect of the presence of clay components and quartz sand on their physical and mechanical properties is studied. The maximum amount of quartzite in the batch mixtures, Aliyans kaolin and Yakkabag sand in particular, is established. It is found that the ramming masses quality is preserved in case the kaolin added and the substitute of quartz sand for quartzite in the refractory mass is not exceeding 25 mass %. Keywords: ramming mass, dinas, refractory materials, factious composition, quartzite, quartz sand, kaolin. INTRODUCTION In connection with the intensive development of industrial production in Republic of Uzbekistan, a comprehensive study of the local raw materials and development, on their basis, of high temperature materials effective compositions is essential. The elaboration of compositions of unmoulded dinas refractory mass based on local raw materials is also one of the most topical issues of the refractory industry in Uzbekistan. It should be noted that Republic of Uzbekistan has huge reserves of mineral raw materials and explores geologically a sufficient number of different fields of highly siliceous rocks, particularly quartzite, vein quartz, sand and other mineral resources to be used for the production of dinas refractory materials and products. The quartz vein deposits are a potential and promising source [1, 2] of raw materials for the production of silica refractory materials. Most of them are distributed in Sultanuizdag, Kyzylkum, Nurata, Kurama and Zirabulak-Ziaetdinsk mountains. Koytash, Kokpatas, Dzherdanak, Kuduk and Sultanuizdag are other noteworthy quartzite deposits. That is why there is a sharp interest towards the complex and rational use of the domestic raw materials and some secondary resources present The aim of this study is to design a composition of a refractory material, on the ground of the natural-raw materials resource of Republic Uzbekistan, to be used for the production of new high-quality dinas printed masses as a substitute of the imported one. EXPERIMENTAL Materials Silica from the Dzherdanak deposits of Surhandarya area, Yakkabag quartz sand and Aliyansk kaolin from Kashkadarya area deposits, as well as Beshtyube deposits bentonite of Karakalpakstan Republics were used as source raw materials for the development of dinas refractory ramming masses. The study was focused on pilot models prepared on the ground of the raw materials mentioned above. 93

2 Journal of Chemical Technology and Metallurgy, 52, 1, 2017 Methods Contemporary methods of physico-chemical analysis as well as methods traditional for the ceramic and refractory technology were used. The compositions of the initial raw materials were identified with the application of chemical and faction analysis. The main characteristics of the dried and burnt pilot models of dinas masses were obtained in accordance with the standard refractory technology methods. The latter referred to the determination of shrinkage (linear size measurement by means of calipers), threedimensional porosity (on the ground of the boiling method), strength on bending and compression with sample destruction using a hydraulic press, etc. In view of the traditional technology of refractory masses production [3, 4] the design of ramming masses optimal composition has to focus at determining properties like: linear change of samples during drying and burning, tensile strength and compression under conditions of drying and burning, porosity of burned potsherds, refractory bodies and a softening temperature under load. This in turn determines the main factors influencing the technological properties of silica ramming masses. They refer to: (i) the content of clay added to the siliceous raw materials; (ii) the replacement of quartzite with quartz sand; (iii) the replacement of clay with calcium oxide; (iv) the use of co-additives like quartzite, clay, and calcium oxide; (v) the introduction of silica battle; (vi) the provision of dispersion of the grain size quartzite and other components of the batch mixture; (vii) the addition of alkali containing components to the mass. The study of the influence of these factors on the technological characteristics of the developed refractory masses was staged in this part of work. RESULTS AND DISCUSSION The results of the chemical analysis of the raw materials used in this study are summarized in It is known [5, 6] that the ceramic and refractory masses particle size plays a crucial role in determining the properties of the ramming mass, especially those connected with heat treatment (burning at high temperatures, for example). This determines the choice of the aggregates fractional composition and particle size. Their values are shown in Table 2. Compositions designated as «quartz- kaolin- bentonite» containing kaolin from 5 mass % to 35 mass % and bentonites (for a plastic mass) from 2 mass % to 5 mass % above Table 1. Chemical composition of the raw materials used. Name of raw Oxides content to air dry matter,% LIC materials SiO 2 AI 2 O 3 Fe 2 O 3 CaO MgO K 2 O Na 2 O TiO 2 SO 3 Dzherdanaksk quartzite 98,7 0,31 0,65 0,15 0,22 0,18 0,56 - minor 1,25 Kaolin "Alyansk" 51,0 33,80 0,47 0,48 0,49 1,48 0,19 0,34 1,12 11,75 Yakkabag sand 97,6 0,08 0,25 0,25 0,13 0,70 0,02 0,01 0,95 1,25 Beshtyubinsk bentonite 62,54 17,06 5,00 0,98 2,02 1,80 1,80 0,82 0,32 7,1 Note: The loss on ignition (LIC) comprises: hygroscopic, constitutional, and crystallized water, as well as organic and volatile compounds and carbon (IV) oxide. 94 Table 2. Fractional composition of the batch mixture starting components. Name of batch mixture components The grain size in mm 1-0,5 0,5-0,2 0,2-0,12 0,12-0,09 <0,09 Dzherdanaksk quartzite 10,01 19,49 18,47 12,01 40,02 Kaolin "Alyansk" 4,51 5,82 9,17 31,81 48,69 Yakkabag sand 0,32 9,44 67,12 15,80 7,32 Beshtyubinsk bentonite 10,31 7,27 81,39 0,72 0,31

3 Azizjon A. Eminov, Zulayho R. Kadyrova, Raisa I. Abdullaeva Table 3. Composition of the masses on the basis of Dzherdanak kvartzite, Alask kaolin and Beshtyubin bentonite. sample Batch mixture composition, in mass % sample Batch mixrure composition, in mass % kvartzite kaolin bentonite kvartzite kaolin bentonite sand К КП К КП К КП К КП К КП К КП К КП К КП Table 4. Test results of burning composition of samples designated quartz, kaolin, bentonite. Change of linear dimensions The volume Strength limit, MPa sample shrinkage after fire shrinkage or porosity,% bending compression drying,% growth,% dried roasted roasted К-1 0,2 +1,4 22,6 1,41 2,38 53,8 К-2 0,3 +1,6 25,0 3,62 2,89 30,7 К-3 2,1 +1,3 26,2 4,35 2,43 23,9 К-4 4,3 +0,8 25,7 5,81 2,96 28,4 К-5 5,2 +0,5 23,6 6,40 3,03 29,2 К-6 6,1-0,4 21,4 7,70 3,15 29,9 К-7 7,3-1,1 14,5 7,61 4,71 33,7 К-8 8,8-0,6 8,2 8,21 5,03 77,3 100 % of the batch mixture are prepared. The samples are gradually heated in a laboratory silite heater at a temperature of 1400 C. The exposure time at the final temperature was 5 hours. Tables 3 and 4 show the batch mixture mass compositions and those obtained upon burning of samples designated as quartzite, kaolin, and bentonite. The study carried out provides to clarify a number of points of interest from point of view of identifying the suitability of the recipe for making batch mixtures of silica refractory ramming mass. The shrinkage after drying increases continuously with increase of the kaolin additives. A reduction of the sample size is obtained in all cases at a given burning rate. However, samples exhibit growth during burning when the content of Alyansk kaolin amounts to 25 mass %. The increase of mineral quartz content in this case results in samples size reduction. It should be noted that the addition of kaolin to 25 mass % is a certain limit, after which the properties of the burned shards change sharply. The shards porosity with the addition of clay to 20 mass % is within the range of 22.6 % mass %. It is also experimentally found that the content of added Alyansk kaolin to Dzherdanak quartz should not exceed 25 %. Its further increase brings about a sharp decrease of porosity and strength increase, due to the appearance of vitrification crock sintered mass. As kaolin is a binder component in the compositions studied, and the extent of dried mass compressive strength increases continuously with increase of the kaolin content. Moreover, the flexural strength limit of the samples containing kaolin from 5 mass % to 25 mass % does not show any significant difference. The compressive strength varies widely for the masses of kaolin content less than 15 mass % - 25 mass %. It reaches very high values in 35 mass % - presence of kaolin. It is worth noting that such a change of the samples compressive resistance can be obviously explained with different nascent amount in the roasted silicate minerals shards. Furthermore, the refractoriness of the quartz-kaoline-bentonite compositions is of great importance and depends on the kaolin amount added. The fire resistance 95

4 Journal of Chemical Technology and Metallurgy, 52, 1, 2017 Table 5. Test results of burned samples of quartz-kaolin-sand-bentonite compositions. Name of samples Fire growth or shrinkage, % Porosity, % Bending strength, MPa КП-1 +1,40 25,92 5,21 КП-2 +1,01 26,90 3,99 КП-3 +0,88 28,05 2,25 КП-4-0,11 26,04 2,31 КП-5-0,16 25,63 2,85 КП-6-0,23 24,97 3,04 КП-7-0,32 24,88 3,36 КП-8-0,22 26,86 1,79 determination shows that the addition of Alyansk kaolin to Dzherdanak quartzite decreases continuously the mixtures fire resistance. Each 5 mass % addition of kaolin decreases the refractoriness observed to 40 о С-70 о С until the mixture content reaches 15 mass %. The fire resistance decrease on further kaolin content increase. The partial replacement of Dzherdanak quartzite by Yakkabag quartz sand is additionally studied. Aiming this, samples in the form of pills of varying content of sand and kaolin are prepared. Results of the study of the physical and mechanical properties of these samples burning at 1400 C are shown in Table 5. Replacing Dzherdanak quartzite by Yakkabag quartz sand in the refractory batch mixture is of considerable interest because sands, Yakkabag sand in particular, are widely spread in nature. Moreover, sand grains are usually sorted by size. They practically represent a mixture of grains of a very small number of fractions. It is impossible to get a high quality clay additive material from a single sand type. Besides, sand is also not very active chemically. Therefore, we test the sand only as a supplement to the quartzite. This procedure saves also raw quartzite. The data in Table 5 shows that the introduction of Yakkabag quartz sand to the mass results in fire growth decrease because of sand s ability to regeneration is less expressed. The porosity of the ramming mass increases with increase of sand content, while the flexural strength decreases dramatically. The masses containing 25 mass % of sand show some improvement in comparison with the mass with no Yakkabag quartz sand. This is explained with the improvement of the total size distribution in the silica refractory ramming mass studied. The fire shrinkage is negligible in case large amounts 96 of Yakkabag sand are introduced to masses of high kaolin content. Strength in bending increases slightly masses containing less kaolin and silica sand. The porosity changes slightly as well. It should be noted that the replacement of quartzite by quartz sand in large quantities, up to 50wt%, leads to a deterioration of they printed masses quality. In general, the amount of the sand added to the refractory mass should not increase above 25 mass %. CONCLUSIONS Charge compositions of dinas refractory ramming masses on the basis of local raw materials of Uzbekistan, Dzherdanak quartzite in particular, are developed. The effect of the added clay component (kaolin and bentonite) and the replacement of quartzite by quartz sand on the physical and mechanical properties of silica refractory ramming mass is studied aiming to select the optimal feedstock composition. The maximum content of additives to the quartzite mass, Alyansk kaolin and Yakkabag sand in particular, is determined. It is found that the amount of the kaolin added to the refractory mass of the quartzite-kaolin-bentonite compositions should not exceed 25 mass %, while the replacement of quartzite by sand should be also up to 25 mass % together with the corresponding clay components added. REFERENCES 1. Mineral resources base of construction materials of the UzSSR, Hdbk. Fan, 1967, p. 600, (in Russian). 2. E.I. Barkovskaya, On the geological surveys of scale 1 : 25000, conducted on the eastern end of Zirabulak

5 Azizjon A. Eminov, Zulayho R. Kadyrova, Raisa I. Abdullaeva mountains in , Report of Zarafshan GRE, Samarkand, T, GGF, 1967, p. 465, (in Russian). 3. R. Hamidov, Determination of areas of exploration and research works in the aluminosilicate, siliceous and carbonaceous refractory raw materials taking into account the needs of industry and available geological prerequisites, T, Funds IMR, 2002, p. 650, (in Russian). 4. Z.R. Kadyrova, F.I. Erkabaev, N.T. Hodzhaev, R.A. Hamidov, Prospects for the use of natural resources of Uzbekistan for production of refractory composite materials. Composite materials, 3, 2005, 9-11, (in Russian). 5. Chemical technology of ceramics and refractory s, I.Y. Guzman (Ed.), M, OOO REEF, Stroymaterialy, 2005, p. 336, (in Russian). 6. K.K. Strelov, I.D. Kascheev, Refractory technology. M, Publishers. Metallurgy, 1988, 528 p. (in Russian). 97