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Tairov Saidamir Saidmalikovich, Ph D., student of the laboratory of Chemistry of silicate, Institute of general and inorganic chemistry Academy of Sciences of Uzbekistan, Tashkent Sabirov Bakhtiyor Tokhtaevich, Institute of general and inorganic chemistry candidate of technical Sciences, senior scientific employee of the laboratory of Chemistry of silicate, Academy of Sciences of Uzbekistan, Tashkent Kadyrova Zulayho Raimovna, doctor of the chemical sciences, professor, Institute of general and inorganic chemistry Academy of Sciences of Uzbekistan, head of laboratory Chemistry of silicate, Tashkent E-mail: [email protected]. Khomidov Fakhriddin Gafurovich, Institute of General and Inorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent
USE OF DUST OF GAS CLEANING OF METALLURGICAL PRODUCTION IN THE COMPOSITION OF CERAMIC MASS FOR FACING TILES
Abstract: The article presents the results of a study on the use of iron-containing waste - dust of gas cleaning of metallurgical industries in the composition of ceramic masses for the development of the composition of facing tiles. It is established that when gas cleaning dust is introduced as a raw material component of a mixture for the development of the composition of ceramic masses, it is possible to obtain facing tiles that meet the requirements of the current standard.
Keywords: ceramic, facing tile, metallurgical waste, dust of gas cleaning, sun dune sand, pegmatite, bentonite, kaolin, composition, chemical, mineralogical, physical and mechanical properties, X-ray phase.
Currently, great importance is attached to the recycling In this paper, we present the results of a study on the design
of waste from various industries in order to solve environ- and development of the composition of ceramic masses for fac-
mental problems by obtaining useful products. One of the ing slabs on the basis of domestic raw materials, using a non-tra-
directions of utilization of such wastes is iron-containing ditional waste - the gas cleaning dust of electric steelmaking fur-
dust of gas purification of metallurgical enterprises for naces DSP-100 of the Uzbek Metallurgical Combine (UMC).
preparation of ceramic mass with the purpose of obtaining Gas cleaning dust is an iron-containing product of steelmaking
facing tiles. production, captured by a filter during the purification of gases
It should be noted that the main raw materials for the pro- coming from electric steelmaking furnaces of DSP-100 of the
duction of facing slabs are clayey and filling components, in Uzbek Metallurgical Combine (UMC). According to the frac-
the form of low-melting and refractory clays, kaolins, quartz tional composition, this waste is a fine dispersible bulk material,
sands, pegmatites, feldspars, as well as wastes of various in- in the form of a grayish-brown and grayish-black color.
dustries [1; 2]. The dust of gas purification, which is formed during
As a result of geological exploration conducted on the ter- the purification of gases from electric steelmaking furnaces ritory of Uzbekistan, the reserves of a number of large deposits DSP-100 UMC, does not emit toxic substances, does not form of non-metallic raw materials for the production of ceramic toxic compounds in air and wastewater, is fire and explosionmaterials for various purposes have been determined and eval- proof and belongs to the group of non-combustible materials. uated. Including clarifies the possibility of using a number of In Table 1 and Table 2, respectively, the results of the industrial wastes of various industries, in the composition of chemical analysis of the raw materials used and the technical the charge for the production of ceramic materials for con- parameters of the gas cleaning dust are developed to develop struction purposes [3; 4]. the composition of the ceramic masses for the facing tiles.
Table 1.- Chemical compositions of raw materials used
Name of raw materials Oxide content (mass.%)
SiÜ2 ^2O3 Fe2O3tota, TiO2 CaO MgO K2O Na2O SO3 LOI
Chirakchys pegmatite 80.17 11.52 0.81 0.75 1.50 0.39 1.20 1.11 1.40 0.95
Logons bentonite 56.60 16.05 5.24 0.57 2.81 1.60 3.97 1.94 0.13 11.04
Angren secondary kaolin 67.40 18.28 1.12 0.37 1.70 0.20 0.70 0.45 0.10 9.17
Yazyavans sun dune sand 57.40 10.78 3.43 0.43 6.15 2.72 2.63 2.15 0.34 9.65
Table 2.- Characteristics dust of gas cleaning
Name indicator Value
Mass fraction of hygroscopic moisture,%, no more than 20.0
The content of the sum of iron oxides (Fe2O3total),%, not less than 45.0
The content of alkali metal oxides (Na2O+K2O),%, no more than 14.0
The content of the sum of sulfuric acid oxides (S03),%, no more than 2.0
Particle size: passage through a grid № 5,%, not less than 100.0
Specific effective activity of natural radionuclides, Aeffect, Bq / kg, not more than 370
X-ray study of crystalline phases dust gas cleaning was carried out on a powder diffractometer XRD-6100 (Shimad-zu, Japan), a controlled computer, using CuKa a radiation (^-filter, Ni, 1.54178 mode of current and voltage tube 30
mA, 30 kW). The constant speed of the detector's rotation is 4 deg / min in increments of 0.02 deg. (w/29-coupling), the scanning coal varied from 4 to 80 degrees.
Figure 1. XRD of iron-containing dust of gas cleaning of metallurgical plant
The figure shows the X-ray diffraction patterns of the iron-containing dust of the gas cleaning of the metallurgical plant. As can be seen from the figure on the X-ray diffraction pattern of the gas scrubbing dust, the diffraction maxima, which are related to minerals of 7-hematite (7-Fe2O3) (d = 0.254, 0.298, 0.211, 0.172 nm)a - hematite (ya-Fe2O3) (d = 0.254, 0.152 nm), wustite (FeO) (d = 0.247, 0.211, 0.152 nm), as
well as peaks with a lower intensity, related to fayalite minerals (Fe2SiO4) (d = 0.247, 0.281 nm), quartz (d = 0.335, 0.230, 0.199, 0.137) and pyrite (FeS2) (d = 0.162, 0.244 nm)
Further on the basis of Chirakchys pegmatite, Logons bentonite, Angren secondary kaolin, Yazyavans sun dune sand, uses dust collectors. The compo-sition of the charge on the basis of the new formulation is shown in (Table 3).
Table 3. - Composition of the raw materials mix of ceramic masses for facing tiles
Name of raw materials Name of samples, composition of charge, mass%
NDG-0 DG-1 DG -2 DG -3 DG -4 DG -5 DG -6 ODG-7
Chirakchys pegmatite 35 30 25 20 15 10 5 25
Logons bentonite 5 5 5 5 5 5 5 3
Angren secondary kaolin 40 40 40 40 40 40 40 42
Yazyavans sun dune sand 20 20 20 20 20 20 20 15
Dust of gas cleaning - 5 10 15 20 25 30 15
To study the physico-mechanical properties of the samples of the facing plates on the basis of the investigated charges, the adopted techniques of ceramic technology were used [5]. First, the starting materials were finely milled in a wet method in a ball mill with an uralite lining and grinding bodies. Furthser, they were mixed with dust by gas scrubbing and co-milled with clay and deoxidizing components for 8-10 hours at a slurry humidity of 48-50% in a laboratory ball mill.
At the same time, the fractional composition of the slip was characterized up to the dispersion; the remainder on the sieve No. 0063 is not more than 2%. The prepared slip was passed through a No. 05 sieve and then subjected to dehydration in gypsum molds. After dewatering to molding humidity, 6.5-7.0% of the mass was sieved through a sieve through No. 2. According to the standard, the dispersion of the granulo-metric compositions of the press powder was determined.
The plasticity of the ceramic masses was determined from the difference between the absolute moisture content of the masses corresponding to the upper yield point and the rolling edge.
Forming of ceramic masses for facing tiles was carried out by pressing the masses of a prototype measuring 300 x x 200 x 7 mm on a press "SACMI-980" at a pressing pressure of 23.0-24.0 MPa. The mechanical strength of the dried tiles at a temperature of 100 °C was an average of 4.8-5.2 kg cm2. The molded tiles were fired at a temperature of 1145 °C on a conveyor-roller line for a total duration of 40 minutes.
The results of a visual inspection of the burnt prototypes showed that all samples were well sintered, had no cracks and deformations. Especially the samples of DG-5 and DG-6 were densely sintered after firing. The obtained results of testing the physical and mechanical properties of the experimental samples are given in (Table 4).
Table 4.- Physico-mechanical properties of samples
Mass name General shrinkage,% Water Absorption,% Strength at bending, MPa Hardness by Mohs
Bnr-0 2.8 15.4 15.2 5
nr-1 3.2 15.0 15.4 5
nr-2 3.8 14.9 16.2 5
nr-3 4.0 14.6 16.7 5
nr-4 4.5 14.2 17.2 5
nr-5 2.8 13.7 17.5 6
nr-6 3.4 13.0 18.6 6.5
nr-7 3.8 14.8 16.9 5.5
according to GOST 6141-91 is not regulated not more than 16.0 not less than 15.0 5
According to [6], ferruginous compounds, in particular iron oxide and pyrite, react chemically with aluminosilicate minerals and very much contribute to the crystallization of an-orthite, mullite and fayalite as well as the formation of a silicate melt, in which iron oxide acts as a modifier to reduce viscosity. As a result, intensive formation of aluminosilicate minerals occurs, giving the finished shard necessary strength and hardness.
The results of the laboratory tests showed that the physico-mechanical and technological characteristics of the sintered prototypes are high enough for all compositions containing
gas purification dust in an amount of up to 15% by mass and without it satisfy the requirement of the current standard. It should be noted that samples containing more than 15% by weight of gas cleaning dust, despite high strength and low water absorption, were deformed and cracked, i.e. characterized by a short interval of sintering.
Thus, it has been established that when dust is introduced as a raw material component of a mixture to develop the composition of ceramic masses, it is possible to obtain facing tiles that meet the requirements of GOST 6141-91.
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