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Iskenderov Akhmed Maksetbaevich, Tashkent Chemical Technological Institute, the associate professor of the faculty of chemical technology of inorganic substances
E-mail: [email protected]
The influence of additives of distilled liquids, containing NaCl and CaCl2 on the process of mineralformation at roasting of sulphate containing blend
Abstract: In this paper the question of use of distilled liquid-withdrawal of the soda manufacture, containing CaCl2 and NaCl as the intensifying additive at burning of a raw mix of sulfo-aluminate-silicate cement, made on the basis ofphosphogypsum and a small with drawal of slaked from lime damper of soda factory, for decrease in temperature of burning at 100 °C and cement improvement of quality has been considered. The amount of distilled liquids, providing maintenance in a raw mix of1% NaCl and CaCl2 is optimum.
Keywords: distilled liquids, phosphogypsum, klinker, sulfo-silicate, cement.
Development of the building industry, accom- substantially pollute environment by the manufacture
pany increase in volumes of building, causes to raise of manufacture of high-quality building materials, to expand their assortment, to introduce new, effective methods of construction. A variety of building designs, feature constructions and essential distinctions of service conditions by different kinds of aggressive influences invoked the requirement of creation of cements with special technical properties. Regulating the structure of new kinds of cement or the structure created on the basis of their composite binding, it is possible to achieve necessary technical characteristics of construction materials.
The important problem, facing the cement industry, is the expansion of a raw-material base at the expense of use of (technogenic) anthropogenic products of other industries. Recycling of industrial wastes is one of rational solutions of a problem of liquidation of environmental contamination, and the large-tonnage of the cement industry will allow to "consume" them in significant amount. In connection with this it is kept an urgency use of large industrial wastes, such as the waste of the soda industry, phospho gypsum, etc. as secondary raw materials.
As is known that the manufacture of soda is accompanied by a considerable quantity of difficultly utilizable liquid waste (in particular — distilled liquid) in the form of solutions of salts CaCl2 and NaCl in the ratio 2:1. Such waste is formed annually in a considerable amount that
Table 1. - Chemical composition of raw materials
of soda.
For increase of clinkerformation speed, the additives are used, accelerating processes of decarbonization and mineralformation, The action mechanism of additives consists in the formation at smaller temperatures on the border of contact of particles of a raw mix of a layer or from the fused mineralizer, or from eutectic melt of min-eralizer with components of a raw mix. As such additives chlorine-containing reagents are most effective and in particular, a distilled liquid of Kungrad soda factory.
According to researches by T. A. Atakuziyev and others it is known that products of roasting blend calcium sulfoaluminate with 0,5% Na2O represent almost practically pure calcium sulfoaluminate. The increase in Na2O content to 1-3% leads to its formation in a small amount. Sodium oxide decelerates reactions of mineralformation of calcium sulfosilicate as well [1].
In connection with this, it presents an interest to investigate the influence of chloride calcium and sodium on roasting blend of the sulfomineral cements.
To this purpose, it has been prepared a raw mix with KH=0,67, for nS=1, to which has been added in various percentage ratio 1-3% NaCl and CaCl2 from raw materials (Almalyk phosphogypsum, Angren deposit enriched clay, soda manufacture solid waste is used as a calcareous component). The chemical composition ofraw materials are resulted in table 1.
Components SiO2 Al2O3 Fe2O3 CaO MgO SO3 R2O TiO2 P2O5 MnO Cl ппп
1 2 3 4 5 6 7 8 9 10 11 12 13
Almalyk phosphogypsum 7,9 0,39 0,15 29,1 0,3 40,44 - 1,53 - - 18,8
1 2 3 4 5 6 7 8 9 10 11 12 13
Angren deposit enriched clay 52,46 31,4 0,61 0,74 0,5 - 1,16 0,52 - - - 12,2
soda manufacture solid waste 0,11 0,11 0,01 88,25 11,3 0,1 0,43 0,01 0,01 0,01 - 10,2
Prepared raw blends with mineralizers have been exposed to roasting at temperatures 1000, 1100, 1150, 1200, 1250 and 1300 ° C within 60 minutes.
For comparison, sulphate-containing blend without additives in parallel has been burnt and exposed to the roentgenophase analysis (fig. l).
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Figure 1. X-rayogram of roasting products In the burnt products with ns = 1,0 at temperature 1250 ° C the height of lines of intensity of a diffraction maximum of minerals C4A3S, C5S2 S, CS, also C2S making accordingly 120, 82, 15 and 45 mm. The obtained product can be carried to SAS (sulfoaluminate silicate cement) clinker with the small content of belite.
Rise in temperature to 1250 ° C showed that at value of ns =1,0 there generally generated minerals C4 A3S, C 5S2 S, and CS, lines of intensity which made accordingly 116, 45 and 34 mm, and lines of intensity C2S were insignificant (6 mm).
1-3 1% NaCl; 4-6 3% CaCl2.
1,4-1100 ° C; 2,5-1200 ° C; 3,6-1300 °C.
Rise in temperature to 1350 ° C showed the following changes in process of mineralformation: lines of intensity C2S and C4AS have decreased to 146 and 140 mm, and the line of intensity CS has increased slightly at ns =1,0. Formation of a fourth mineral (5 mm) is observed. Thus, at temperature of roasting of blend 1150 ° C and ns =1,0 it is obtained the clinker, containing minerals C4 A3 S , C5S2 S, and C2S. At temperature 1350 ° C and ns=1,0 it is obtained the SAS clinker with the large content of C2S and CS.
Rise in temperature to 12500 C showed that at value of ns =1,0 there generally generated minerals C4 A3S, C 5S2 S, and CS lines of intensity which made accordingly 116, 45 and 34 mm, and lines of intensity C2S were insignificant (6 mm).
Rise in temperature to 1350 ° C showed the following changes in the process of mineralformation: lines of intensity C2S and C4AS have decreased to 146 and 140 mm, and the line of intensity CS has increased slightly at ns =1,0. Formation of a fourth mineral (5 mm) is observed. Thus, at temperature of roasting of blend 1150 ° C and ns = 1,0 it is obtained the clinker containing minerals C 5S2 S, C 5S2 S, and C2S. At temperature 1350 ° C and ns =1,0 it is obtained SAS clinker with the large content of C2S and CS.
Results of roentgenophase analysis testify that already at 1100 ° C C 5S2 S, C4 A3 S, unbound CS are generated, lines of intensity which make accordingly 82, 31 and 13 mm. However, it is necessary to notice that thus the content of unbound CS is much less than in products of roasting without mineralizer on which X-rayograms which the line of intensity CS makes 32 mm. Besides, C4A3S which defines strength characteristics of sulphate containing cement, forms in rather small amount (32 mm) whereas lines
of intensity C4A3S without mineralizer in roasting products are equal to 41 mm.
Calcium chloride has been applied as mineralizer for a long time in the USA at roasting of the glauconite containing rocks in revolving furnaces for industrial obtaining of cement and salts of potassium [2].
Introduction of Portland cement CaCl2 (1%) in a raw mix rather activates the process of assimilating lime in kiln charge [2].
The researches, carried out with addition of calcium chloride, show that the presence of CaCl2 in sulphate containing mixture in amount of 1, 2 and 3% and roasting at 1000 ° C, leads to assimilating lime practically full.
Results of roentgenophase analysis testify that at addition 3% CaCl2 and temperatures 1100 ° C C2S and unbound CS are generated, lines of intensity, which make accordingly 51 and 10 mm. It is necessary to notice that thus C5S2S does not generate, and the height of diffraction maximum C 4 A3S is equal to 500 mm, i. e. formation of SAS clinker does not occur, but a sulfoaluminate-belite clinker generates.
Rise in temperature to 1200 ° C at roasting of sulphate containing blend with addition the halogen containing mineralizer the following changes occur in the process of clinkerformation.
When 1% NaCl was added in roasting products there generated minerals C5S2 S, C4A3S and unbound CS, the intensity of lines, which make accordingly 80, 39 and 8 mm. Thus the line of intensity C5S2 S is less than in roasting products without mineralizer where lines of intensity of the specified mineral make 95 mm, unbound calcium sulfate are absent, i. e. NaCl opposes the formation of calcium sulfosilicate a little. However, at addition of NaCl the content of C4A3S is more than in products of roasting with the same additive at temperature 1100 ° C where the line of intensity of the last is equal to 32 mm. At roasting ofblend with an additive 3% CaCl2 only minerals C2S and C4A3 S (d=0,287 of nanometer) generate, lines of intensity which are equal to accordingly 49 and 54 mm whereas in the products of roasting, obtained without mineralizers, there generate C5S2 S and C4A3S. The amount of C4A3 S increases in comparison with products of roasting at 1373 K with an additive of CaCl2 where the line of intensity C4A3 S is 50 mm.
Rise in temperature to 1300 ° C shows that addition of the halogen containing of mineralizer gives other character to the process of clinkerformation.
Roasting with NaCl testify that are thus minerals C2S, unbound CS and C4 A3 S, lines of intensity which make
accordingly 49,39 and 28 mm whereas in products of roasting without mineralizers there generate C 5S2 S, C2S, C4A3 S and unbound CS, lines of intensity which are equal to accordingly 43, 29, 35 and 8 mm.
Absence of C5S2 S at addition of NaCl is connected with the decomposition of C5S2 S into C2S and CS, therefore the contents of C2S and CS (unbound calcium sulfate) increase. Besides, it are necessary to notice that at temperatures 1100 ° C and 1200 ° C in roasting products with an additive of NaCl there generated only C5S2 S, C4 A3S, and unbound CS, and the line of intensity C2S is absent.
In roasting products with an additive of CaCl2 only C2S, C4A3S and CS with lines of intensity 63,18 and 22 mm accordingly, whereas in the roasting products obtained without mineralizer, C5S2 S, C4 A3S and unbound CS generate. Similarly previous, here, there is a decomposition of sulfosilicate into belite and unbound calcium sulfate too (fig. 1).
With CaF2 minerals C2S, CS, C4A3 S with lines of intensity accordingly 45, 31 and 48 mm are generated, and sulfosilicate is not generated, whereas in the roasting products obtained without mineralizer, the line of intensity makes 43 mm. It is necessary to notice that the line of intensity unbound CS is more six times than in the roasting products obtained at temperatures 1100 ° C and 1200 ° C (with an additive of CaF2). The line of intensity C 5S2 S is much more — accordingly 75 and 72 mm. The line of intensity C4A3 S at 1300 ° C is less (31 mm) than in roasting products at 1100 ° C and 1200 ° C where the intensity of line C 4 A3S is accordingly 38 and 37 mm.
Thus, results of the carried out researches at temperatures 1000-1300 ° C with addition of 1-3% CaCl2 in the sulphate containing mix of NaCl, leads to the following conclusions:
- assimilation of lime at addition of CaCl2 completes at temperature 1000 ° C, i. e. the temperature of roasting falls to 100 ° C;
- application of CaCl2 (3%) as mineralizer at 1100 ° C opposes the formation of C 5S2 S, i. e. SAB clinker is generated;
- the additive of CaCl2 (3%) at 1200 ° C opposes the formation of mineral C 5S2 S, where there are generated only C2S and C4A3S ;
- addition of 1% NaCl at 1300 ° C leads to the formation of SAB clinker, i. e. sulfosilicate is absent;
- at 1200 ° C the additive of 1% NaCl reduces the content of C 5S2 S and increases the amount of unbound CS.
Research on the purification process of low-grade sodium chloride
References:
1. Атакузиев Т. А. Физико-химические исследования сульфатсодержащих цементов и разработка низкотемпературной технологии их получения. / Ташкент, - Фан, - УзССР, - 1983, - С. 102.
2. Бутт Ю. М., Тимашев В. В. Портландцементный клинкер. - М.,/Стройиздат, - 1967, - С. 303.
Iskenderov Akhmed Maksetbaevich, Tashkent chemical technological institute, the associate professor of the faculty of chemical-technology of inorganic substances E-mail: [email protected] Erkaev Akhtam Ulashevich, Tashkent chemical technological institute, the associate professor of the faculty of chemical-technology of inorganic substances
Toirov Zokirjon Kalandarovich, Tashkent chemical technological institute, the associate professor of the faculty of chemical-technology of inorganic substances Begdullaev Akhmed Kobeysitnivich, the main specialist on the innovation and new technology UE "Kungrad Sodium Plant."
Research on the purification process of low-grade sodium chloride
Abstract: The theoretical analysis on the purification process of brine has been carried out with the usage of solubility isotherms of reciprocal systems Ca2+ ,2Na + //2Cl- ,SO] - H2O . By experimental investigations it has been determined that the purification of low-grade sodium chloride with the application of distilled fluid in the production of soda ash can increase the coefficient of sodium chloride to 0,5-2, 0% and decrease water consumption and lime to 3-8%.
Keywords: sodium chloride, distilled fluid, theoretical analysis, soda ash, water consumption.
In Uzbekistan the reserves of salt deposits of Bar- grab crane in the capacity for dissolving salt, where dis-
sakelmes, located in 30 km from UE «Kungrad Sodium solved by water (volume — 2500 m 3) with the obtaining
Plant» (UEKSP), have been chosen as the base of chlo- of crude brine, containing 26,41% NaCl. The dissolution
rine-sodium raw materials. occurs in the cylindrical apparatus with a square hopper
Salts must be subjected to the purification from ad- for receiving solid salt with the inner distributing devices
ditives of salt calcium and magnesium. For example, for for inputting water and steam and overflow the top of the
this purpose in the Crimea Sodium Plant a new two- chute. The crude brine with the temperature of 44 °C
staged lime-sodium method of brine purification [1] overflows into the container, intermediate container of
has been developed and implemented. With the pur- brine, which is cylindrical vessel with the volume flat cap
pose of intensification of this process, the suspension of 2500 m 3 [2].
of calcium hydroxide is quenched by crude brine and The initial brine is pumped in the capacity of raw
the formed suspension is fed to the mixing with brine, brine with the volume of 3500 m 3, which is delivered to
and it is subjected to the purification (purification stage the container for mixing. Solutions of lime milk and soda
of brine from magnesium). ash are delivered into this container at the temperature
In the technology of obtaining soda ash in UE KSP, of 50 °C. In the reactors the binding of cations Ca 2+ and
solid salt from storehouse is delivered with the help of Mg 2+ is occurred with the formation of insoluble combi-
