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Matkarimov Sokhibjon Turdaliyevich, Tashkent state technical university, Tashkent, Uzbekistan E-mail: sohibtm@gmail.com
EXTRACTION IRON AND ITS COMPOUNDS FROM STEEL-SMELTING SLAGS SC "UZBEKSTEEL" BY USING GRAVITATION METHODS
Abstract: The problems of extraction iron and its oxidized compounds from steel smelting slags are considered in the article. It is shown that there is noticeable amount of the iron, which concentration comparable to poor iron ores of Uzbekistan, after allocation of magnetic components in dump slags. Various methods are investigated for their allocation, and gravitational enrichment on a concentration table is recognized as the most optimum technology.
Keywords: slag, oxide components, extraction iron, ecological problems, steel smelting slag, extraction, magnetic components, gravitational extract.
For years of independence the Republic of Uzbekistan has turned into dynamically developing state which is moving ahead on the way of technological progress.
Problems of rational use of natural resources and environmental protection are under constant attention of the leadership of the Republic of Uzbekistan [1].
The basic concepts of waste-free and low-waste technology are so far formulated; the main objectives and the directions of their development are planned. Features are revealed and the main directions of development waste-free and low-waste technologies of mining and metallurgical productions which consist in development of essentially new directions, nonconventional ways and improvement of the existing production technologies, for reduction at all his stages of harmful emissions of complexity of use of raw materials and full use of the formed waste are planned. It directly concerns also the only enterprise of ferrous metallurgy in the Republic, SC "Uzbeksteel".
The main source of raw materials for production of steel and various alloys on the basis of iron in SC "Uzbeksteel", is secondary ferriferous scrap and waste. The raw materials arriving on SC "Uzbeksteel" after primary preparation are processed according to the pyrometallurgical scheme, fusion in metallurgical furnaces. Melting of ferriferous raw materials on SC "Uzbeksteel" is made in two types of furnaces:
- the martin furnace using carbonaceous fuel;
- the arc steel-smelting furnace working at electric energy.
When melting ferriferous raw materials in both types of furnaces, at the expense of the proceeding physical and chemical changes steel-smelting slags are formed. The maintenance of Fetal in the formed slags makes the considerable size (50-70%), and pure iron of 10-12%. Now on Uzbeksteel these slags for extraction of ferriferous components and pure iron are exposed to crushing, crushing and magnetic sepa-
ration. After processing slags contain 15-25% of the sum of Fe2O3 and FeO and also 2-4% of Femet. These slags aren't processed and stored now in special dumps while when melting steel in the martin and arc steel-smelting furnace as oxidizers apply Fe2O3, FeO, iron ore, scale, agglomerate, iron ore briquettes and other materials abroad, for currency. At the same time the plant incurs substantial damages on the organization and operation of slag dumps.
Today reserves of slags make 1-1,5 million tons, the annual gain makes 60-80 thousand tons [2].
When carrying out approximate calculations it is possible to see that the quantity of Fe2O3 which is contained in the saved-up steel-smelting slags is 100-150 thousand tons, and the amount of pure iron is 20-40 thousand tons. As a result of extraction of iron and its connections from steel-smelting slag the volume of the oxidizer delivered from abroad will be reduced by 6.0-10.0 thousand tons when processing 60.0-80.0 thousand tons of steel-smelting slags in a year. Besides, it will have also considerable social effect since the ecological situation around the plant improves.
As a result ofthe research works which are carried out at de-partmentof Metallurgy it has been established that for extraction of iron and its compounds from the processed steel-smelting slags application of methods of gravitational enrichment is possible. The fact that about 90% of iron and manganese ores are enriched with gravitational methods also demonstrates to it and also individual share of gravitational methods in processing of the oxidized iron ores annually increases [3].
For definition of an optimum way of extraction of iron and its connections the following methods of gravitational enrichment have been used: jigging; enrichment on a screw separator; enrichment on a concentration table.
Optical properties of Fe2O3 sample were determined through UV-spectrum. The optical absorption spectra was recorded by using SHIMADZU IRAffinity - 1 (Figure 1).
Table 1. - Chemical consists steelmaking slag SC "Uzbeksteel"
Fe FeO Fe2O3 CaO SiO2 Al2O3 MnO MgO P2°5 SO3 Others
1.5-1.6 7.4-9.8 15.4-17.5 22.0-26.0 24.0-28.0 5.8-7.0 7.9-10.2 7.61-10.7 0.2-0.13 0.2-0.26 2.8-5.1
100
%T
75
50 1748,55—t 645,35—Q H7,74-C,
25 — 'i ni^IT \ Vk
-0
- „
4500 4250 4000 3750 3500 3250 3000 2750 2500 2250 2000 1750 1500 1250 1000 750 500 17,01,2018 Sohib 1pr 1/cm
Figure 1. UV-spectrum of steel smelting slag SC "Uzbeksteel"
The UV spectrum of iron oxide manifests prominent absorption band located at 398.32, 434.00 and 507.37 cm-1.
3,350 s tri
1 -jp of
o- 1 1 1 J s............ S m S SJ ___ X 2,700 - 2,285 AvA i,6i J
Figure 2. XRD pattern of steel smelting slag SC "Uzbeksteel"
The structural features of minerals are explored from XRD date (Figure 2). They are: anortit with sodium feldspar - 4.265; 3.343; 1.813; 1.539 Ä; mullite - 2.855; 2,452 Ä; hematite - 2.696; 2.518; 1.834; 1.688 Ä; enstatit - 3.157 Ä; magnetite 2.541; 1.612 Ä.
Table 2.- Particle size distribution of the processed steel-smelting slag
On the structure steel-smelting slags are self-breaking up and low-active. The maintenance of Fe in slags fluctuates within 50-70%, pure iron - 10-12%.
Class, mm Mass, kg Out put,% Total «+»,%
1 2 3 4
+3.0 0.859 17.18 17.18
-3.0+2.5 0.280 5.6 22.78
-2.5+2.0 0.320 6.4 29.18
-2.0+1.5 0.470 9.4 38.58
-1.5+1.2 0.243 4.86 43.44
1 2 3 4
-1.2 2.828 56.56 56.56
Total 5.0 100 100
Extraction of iron and its connections from the processed steel-smelting slags is based by method of a jigging on a difference of speeds of a motion of grains in the pulsing environment [4]. The jigging was carried out in the laboratory two chamber jigger. At a jigging initial material is exposed to division into the layers differing on density and fineness which are formed on a jigger sieve in a result of periodic action of the ascending and descending streams of
the dividing environment, the driving mechanism caused by work. In the lower layers the heavy product, and in the top-easy concentrates.
The hinge plate of the processed steel-smelting slags weighing 5.0 kg was exposed to a research. Average values of results of 5-6 pilot studies are presented in (tab. 2). In experiments tails of the first jigging loaded again into the jigger therefore received two concentrates.
Table 2.- Qualitatively - a quantitative index of division of valuable components of the processed steel-smelting slag at a jigging
Products Out put,% Content,% Extraction,%
kg % FeO+Fe2O3 Fe FeO+Fe2O3 Fe
Original 5.0 100 17.6 3.8 100 100
Concentrate 1 2.45 49 15.2 2.21 42.3 28.6
Concentrate 2 1.05 21 16.8 2.3 20.0 12.8
Tails 1.5 30 34.4 7.4 37.7 58.6
At enrichment on a screw separator the uniformity of Results of distribution ofvaluable components of the pro-
food was maintained. An amount of water in food it was set cessed steel-smelting slags at enrichment on a screw separator
at the rate of receiving a pulp with a density of20-30% of firm. are given in (tab. 3). The consumption of flushing water is regulated visually and averages 0.05-0.2 p/a.
Table 3.- Qualitatively - a quantitative index of division of valuable components of the processed steel-smelting slag on a screw separator
Products Out put,% Content,% Extraction,%
kg % FeO+Fe2O3 Fe FeO+Fe2O3 Fe
Original 5.0 100 17.6 3.8 100 100
Concentrate 1 2.10 42.0 15.42 2.96 38.6 32.7
Concentrate 2 1.75 35.0 9.35 2.32 18.6 21.4
Tails 1.15 23.0 35.12 7.58 42.8 45.9
Analysis of data of (tab. 3) shows that losses with tails make considerable size that significantly reduces indicators of process and can hardly be an effective method of processing of the fulfilled steel-smelting slags.
At extraction of iron and its connections on a concentration table division of materials of slag comes from the processed steel-smelting slags in thin water flow, (sound board) flowing on a low-bevel flat surface of a table [5]. The sound board makes asymmetric returnable step the movements in the horizontal plane.
Pilot studies were conducted on a laboratory single-tier concentration table of LKS - 1Ya. The table is intended for material enrichment by fineness - 3 mm, productivity of a table of 15-20 kg/h; the size of the course of a sound board
is regulated in repartitions of 8-16 mm; number of the courses in a minute 275-325; inclination of a sound board from 0 to 100; water 0.5 consumption of m3/h [6].
After establishment of technical indicators of a table began performance of pilot study.
At first water in the quantity sufficient for a covering was pumped by a thin layer of all surface of a table. The processed steel-smelting slag moved in a loading box of a table in the form of the pulp received after crushing with L: S relation= = 2:1.
Qualitative quantitative indices of enrichment of the crushed processed steel-smelting slags on a concentration table are given in (tab. 4).
Table 4.- Average values qualitatively - quantitative indices of division of valuable components of the processed steel-smelting slag on a concentration table
Products Out put,% Content,% Extraction,%
kg % FeO+Fe2O3 kg % FeO+Fe2O3
Original 5.0 100 17.6 3.8 100 100
Concentrate 1 1.46 29.3 37.9 10.2 63.0 78.2
Concentrate 2 1.2 24.0 16.8 1.73 22.8 11.2
Tails 2.34 46.7 5.3 0.9 14.2 10.6
By results of the conducted researches it is visible that at enrichment of the processed steel-smelting slags on a concentration table extraction of valuable components makes,%: a concentrate 1 - FeO + Fe0-63.0; Fe - 78.2; a concentrate
2 - FeO + Fe2O3-22.8; Fe - 11.2.
The comparative analysis of indicators of extraction of FeO, Fe2O3 has been made for the choice of an optimum way of gravitational enrichment of the processed steel-smelting slags, Fe results of which are given in (tab. 5).
Table 5.- The comparative analysis of extraction of useful components from the processed steel-smelting slags by method of gravitational enrichment
Method extraction Extractive valuable compounds Extraction,%
Concentration - 1 Concentration - 2 Tails
Jigger FeO+Fe2O3 42.3 20.0 37.7
Fe 28.6 12.8 58.6
Screw-separator FeO+Fe2O3 38.6 18.6 42.8
Fe 32.7 21.4 45.9
Concentration table FeO+Fe2O3 63.0 22.8 14.2
Fe 78.2 11.2 10.6
As a result of the carried-out comparison of results of enrichment of the processed steel-smelting slags, it is established that an optimum method at which the maximum extraction of FeO, Fe2O3, Fe is reached is enrichment of the processed steel-smelting slags on a concentration table.
The analysis of chemical, fractional and mineralogical composition of the processed steel-smelting slags is carried out.
It is established that for processing of these slags by the most acceptable use of gravitational enrichment is.
Conclusions: 1. It is shown that from all studied enrichment methods the most suitable technical and economic and technological indicators are received at enrichment of slags on a concentration table which can be recommended for industrial introduction.
2. Use of this development in the industry will allow to expand a source of raw materials of plant without capital expenditure for geological and mining operations and to pass to low-waste technology. At the same time waste slag can be actually eliminated that will favorably affect an ecological situation around iron and steel works.
References:
1. Sanakulov K. Scientific and technical bases of processing of waste of mining and metallurgical production.- Tashkent: Publishing house of FAN of AC of RUz, 2009.- 404 p.
2. Yusupkhodjayev A. A., Valiyev X. R., Khudoyarov S. R., Matkarimov S. T. Increase in efficiency of steel-smelting production by additional recovery of valuable components from the utilized slags.- M.: Magazine of "Ferrous metals", 2015.-No. 1. 19-22 p.
3. Matkarimov S. T. and others, Studing methods of extraction iron and its compounds from steel-smelting slags // Proceedings of the international conference on integrated innovative development of Zarafshan region: achievements, challenges and prospects, Navai, 26-27 october 2017.- P. 182-184.
4. Yusupkhodjayev A. A. Theory waste free technology on the ferrous metallurgy.- Tashkent: TSTU, 2017.- 4 p.
5. Matkarimov S. T. and others, Researching of an optimum way of extraction of iron and its compounds from the steel-smelting slags / Proceedings of the international conference "Scientific-technical progress as factor of improving modern civilizations",- Magnitagorsk,- 14 November, 2017.- P. 77-81.
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