CC BY
17
ХИМИЧЕСКАЯ ТЕХНОЛОГИЯ
UDK 691.541 691.512
N. S. Shelihov, R. Z. Rahimov, R. R. Sagdiev, O. V. Stoyanov
MODIFIED HYDRAULIC LIME AND ROMANCEMENT FROM MINERAL RAW MATERIAL
OF TATARSTAN
Keywords: limestones, dolomites, hydraulic lime, romancement, zeolites.
The article discusses possibility to extend the interval of suitability of mineral raw material and to use it in receiving hydraulic lime and romancement not only clean limestones, but also limestones with 21% of MgO. To receive the mineral cement artificial raw material mixtures from carbonate raw material and clays were used. Carbonate raw material with 0,8% to 21% of MgO was used. The carbonate and clay constituents of the mixture was correlated by the coefficient of saturation. At the coefficient of saturation no less than 1.3 strong hydraulic lime with durability no less than 12 MPa is received is received. To receive romancement raw marerial mixtures with the coefficient of saturation 0,65-1,3 were used. The durability of the resultant romancement is no less than 20 MFa. The use of artificial additives as the grind zeolites in hydraulic lime and romancement allowed to promote considerably the durability of mineral cement to 66% of romancement and to 80% of hydraulic lime. Modified hydraulic lime and romancement were used to receive low stable solutions and concretes of small durability and also dry building mixtures.
Ключевые слова: известняк, доломит, гидравлическя известь, романцемент, цеолиты.
В статье рассматривается возможность увеличения интервала пригодности минерального сырья и использование не только чистых известняков, но и известняков с 21% MgO, в получении гидравлической извести и ро-манцемента. Для получения минерального цемента были использованы искусственные сырьевые смеси из карбонатного сырья и глин. Было использовано карбонатное сырья с MgO от 0,8% до 21%. В смеси карбонатные и глинистые компоненты коррелируют с коэффициентом насыщения. С коэффициентом насыщения не менее 1,3 получена сильного гидравлической известь с прочность не менее 12 МПа. Для получения романцемента сырьевые смеси были с использованием коэффициента насыщения 0,65-1,3. Прочность полученного романцемента не менее чем на 20 MРa. Использование искусственных добавок, как молотых цеолитов в гидравлической извести и романцементе позволило значительно повысить прочность минерального цемента до 66% у романцемента и 80% гидравлической извести. Модифицированный гидравлическая известь и романце-мент были использованы для получения низкомарочных растворов и бетонов, а также сухих строительных смесей.
Introduction
The urgency of the development of energy and resource saving technological process in the production of mineral cement substances has received recently especially in the period of energy crisis phenomena in Russia and abroad.
The energy saving approach in the production of mineral cement substances should be based on the use of local raw material resources and wastes from industry, expansion of an interval of suitability of raw material, the reduction of energy costs for production (the decrease of calcinations temperature or heat treatment, the duration of technological processes, etc.), the use of the additives for quality modifications.
Such approach has been used recently at carrying out the scientific research at the Faculty of building materials at KSUBU, in particular during the development of technological bases of receiving low stable hydraulic mineral cement (hydraulic lime and romancement).
In a number of regions of Russian Federation, including Tatarstan, there is no own production of hydraulic minereal cements on the basis of local carbonate raw material. It is connected with a number of reasons, one of which is the inconstancy of chemical structure of carbonate rocks. For example, there is a very little
amount of pure limestones in Tatarstan. Mainly the limestones contain dolomite. (table 1).
The degree of dolomite even varies within the limits of one deposit, from dolomite limestones (MgO no less than 1,1% up to pure dolomites (MgO no less than 21%).
Table 1 - Chemical structure of carbonate raw material in developed depositsof Tatarstan
In various structures the amount of oxides of magnesium can be changed from a level of impurity up to a level of the basic component. The use of such magnesium rocks in production of hydraulic mineral cement
Deposits Quantity, % Average density, t/m3
MgO CaO
Matyushino 12,84-21,17 22,3-32,07 2,3
Potanikha 1-17,72 25,17-51,58 2,09-2,43
Kovaly 2,39-18,7 21,09-47,46 1,7-2,0
Kurguzy 12,78-19,19 22,32-35,95 2,0-2,4
B. Karmaly 13,8-21,7 21,12-32,65 1,7-2,5
Derjavino 14,04-22,71 21,84-38,26 1,7-2,4
Nikiforovo 15,12-18,51 30,89-34,90 2,1-2,2
Kurkachi 4,96-15,69 4,89-43,56 2,34
can result either in overheating of MgO and overdue hydration, or in unsufficient output of hydraulically active minerals.
The purpose of the present work is to study the chemical and technological features of inconstant structure on a ration between CaO and MgO, ensuring:
- maximal quantity of the main components of mineral cement
- high activity of mineral cement
- optimum mode of hardening and structure formation excluding abnormally high contents of MgO in mineral cement
Methods and materials
The low stable mineral cements are products of high temperature treatment of marlous limestone, marles or artificial mixes of limestone with clay at temperatures which do not bring to sintering of products.
Hydraulic limestone is a product of high temperature treatment of marlous limestone of thin dispersive clay and sandy admixtures from 6 to 25% or artificial mixes of similar structure.
In the scientific and technical literature the data on the use of carbonate raw material and with a wider interval of the contents of 1.5 oxides and magnium carbonate are given. For example, V.N.Yung [1] gives examples of the use of carbonate raw materials with the contents CaCO3 from 70 up to 90%, MgCO3 up to 10%, 1.5 oxides from 10 up to 30%. According to K.Shokh [2] even in 30-s of 20 century for the production of lime in Germany there were used dolomatic Vyurtenberg marls with the contents of MgCO3 up to 40%.
Romancement is a product of high temperature treatment of marlous limestones. To receive romancement the artificial mixture of limestone and clay can also be used.
Generally carbonate raw material should provide such ratio between carbonate and clay components
that the whole CaO, formed by high temperature treatment are joined in silicate, aluminate and ferrite. It is achieved when limestone marls as well as marls containing clay no less than 25% or artificial mixtures of carbonate raw material and clay are used. Analysis of the scientific and technical literature [3-6] shows, that in different time for romancement the raw material with the contents of
- CaCO3 from 56% to 72%
- MgCO3 from 1%to 7% (sometimes to
35%)
- the rest are clay components were used.
For tests two component compositions on the
basis of carbonate raw material of Potanikhin deposit and clay raw material of Kalinin deposit were taken.
Structures of mixes included the extreme representatives of carbonate group from limestones to dolomites. The chemical structure of components of raw mix is submitted in Table 2.
The account of structures was made according to saturation factor (1), which takes into account the linkage of CaO, formed as a result of high temperature treatment of raw material into silicate, aluminate and ferrite.
Theoretically at complete linkage of CaO and SiO2 in 2CaOSiO2 factor of saturation which isdetermined by formula (1) is equal to one. Practically for romancement it should be within the limits of 0,90,95. For hydraulic lime, containing free CaO factor of saturation should be more than one.
CaO-(1,65Al2O3 +0,35Fe2O3 +0,7SO3 ) ^
KH--(1)
1,86SiO2
When two carbonate mixture from carbonate rock and clay is calculated we take the amount of the first for X, the amount of the second for 1.
Table 2 - Chemical structure of raw material
Quantity, %
Materials CaO SiO2 Al2Os Fe2Os MgO LOI E
Dolomite 31,85 - 1 0,89 19,85 46,41 100
Clay 1.9 69,7 13,1 6,1 2 7.2 100
Limestone 53,1 2,5 - - 2,2 42.2 100
The structure of the substance after the incandescence
Dolomite 54,43 - 1,86 1,66 37,0 - 100
Clay 2 75,1 14.1 6,6 2.2 - 100
Limestone 91,8 4,3 - - 3,8 - 100
Then the average weighed amount of oxides in a mixture of two components will be determined at the following proportions
xAj + Ä2 xF, + F2
Ао _ , ; Fo _ 1 , ; (2)
x+1
x+1
С _ xC 1 +C 2 ; S _ Со- - ; SO _
x +1
XS1 + S2
x+1
Where CaO -C; SiO2 -S; M2O3 - A; Fe2O3 - F. The quantity of carbonate component will be determined by the following formula
_1,86S2-KH+1,65A2 +0,35F2 -C2
X_ C1-1,86S1KH-1,65A1-0,35F1
As a result of account the limiting ratio between carbonate compound clay were established:
- in receiving the romancement the ratio between dolomite and clay should be no more than 3,2:1; the ratio between limestone and clay should be no more than 1,94:1;
- in receiving hydraulic lime the ratio between dolomite and clay should be more than 3,2:1;
- the ratio between limestone and clay should be more than 1,94:1.
The growth of MgCO3 increases the ratio between carbonate rock and clay.
During the creation of artificial raw mixes the factor of saturation was changed in an interval KH=0,65-1.3.
One of the main tasks when magnesium raw material is used in production of hydraulic mineral cement, is to receive MgO in an active condition as a result of high temperature treatment, not to admit its overheating as well as to ensure the highest quantity of mineral cement.
For this purpose the total effect of competing processes taking place during the high temperature treatment: ascending - termal dissociation of carbonate raw material (according to the MgO+CaO amount) and descending -the change of the activity of a formed MgO was determined.
Results and discussion
The maximal total effect corresponds to the temperature of high temperature treatment 800O C and is equal to 1,5 of standard units. However large percent of lowheating and smaller quantity of mineral cement in this case is observed.
The increase of temperature of high temperature treatment up to 850-950O reduces a little the total effect but raises an quantity of mineral cement at the sufficient activity of MgO.
The high temperature treatment of various structures of raw mixes in various temperature and time intervals allowed to offer optimum modes of calcina-
tions for raw material with the various contents of MgCO3 (table 3).
X raying and structural analysis of products of calcinations of various structures of mixes at various modes is submitted in table 4.
Analysing the structure of products of calcinations it is possible to notice that from the same raw material by changing the factor of saturation and the ratio between components it is possible to receive mineral cement both with free CaO, and with completely connected in silicate and aluminate. So it is possible to receive both hydraulic lime and romancement (in the table the blacked out cells). In analyzing the results of laboratory and technological research of carbonate -clay raw material, the chemical structure of which is changed within wide limits, it has been established that the basic parameters in estimating the quality of raw material are the contents CaCO3, MgCO3, SiO2, Al2O3, Fe2O3, alkaline oxides and free silica.
The possible limits of changing the contents of the above-stated components of carbonate raw material established by us, are submitted in table 5.
With the purpose of study the possibility of increasing the solidity characteristics of low stable hydraulic mineral cements by linking free CaO mineral additives were used. For additives the zeolites of the Tatar-Shatranskoe deposit of were used, the average chemical structure of which is the following: CaO -17,3%; MgO -1,8%; SiO2-67,5%; Al2O3-6,7%; Fe2O3 -2,4%; The rest-4,3
The reasons why those additives were chosen as the components for compositions with unstable hydraulic mineral cements was the information about their positive influence on the characteristics of mineral cements.
The additives of zeolites were added to mineral cements in the amount from 20% to 10%. The process of mixing was carried out in a spherical mill.
The research of influence of the additives was carried out on structures received at an optimum mode of high temperature treatment.
Kind of mineral cement Mode of heat treatment
MgCO3 is more, than 5% MgC03 is not more, than 5%
Temperature, 0 C Time, hour Temperature 0 C Time, hour
Hydraulic lime
- low hydraulic. 800-850 3,5-3 950-1000 3-2
- high hydraulic. 850-900 4-3,5 1000-1100 2-1
- romancement 850-900 3-2,5 1000-1100 2,5-2
Table 3 - Modes of high temperature treatment of raw material to receive hydraulic lime and Romancement
Вестник Казанского технологического университета. 2015. Т.18, №3 Table 4 - Modes of calcinations of raw material to receive hydraulic lime and romancement
Saturation coefficient - 0,8
Minerals Quantity, %
Calcination temperature, °С
750 850 950 1100
The relict minerals 33 15 tracks tracks
C3S - - tracks tracks
C2S 2,6 20,1 30,8 30,8
CA 6,6 7,6 8,3 1.3
CF - 3,2 1,2 -
C2F - 4,6 9,8 -
C4AF - - - 9,8
C3A - - 6 13,9
CaO 25,4 13,1 4,2 1
MgO 21,1 23,1 25,3 27,3
SiO2 11,3 13,3 15,5 15,7
Saturation coefficient - 1,3
Minerals Quantity, %
Calcination temperature, °С
750 850 950 1100
The relict minerals 30 15 tracks tracks
C3S - - tracks tracks
C2S 2,6 13 17 20
CA 6,6 7,6 8,3 1.3
CF - 3,2 4,2 -
C2F - 4,6 6,8 -
C4AF - - - 9,8
C3A - - 6 10
CaO 28,4 20,2 18 18
MgO 21,1 23,1 24,2 25,2
SiO2 11,3 13,3 15,5 15,7
Table 5 - Recommened structure of carbonate raw material for the production of hydraulic lime and romancement
Substances Quantity in carbonate
raw material, %
For hydraulic For
lime romancement
CaCO3, 50-70 50-70
MgCO3 0-25* 0-35**
Al2O3 4-10 4-10
SiO2 4-15 10-25
Fe2Os 2-4 2-4
Total quantity 6-25 no less 25
SiO2+ AbOs+
Fe2O3 Na2O+K2O less 1 less 1
Free SiO2(as sand) less 3 less 3
*Magnezium hydraulic lime. **Magnezium romancement
The results of research have shown, that the introduction of zeolites results in significant increase of durability(solidity) of mineral cements (fig.)- on 45% for romancement and on 83% for hydraulic lime. X ray-structural analysis has shown that it is connected with additional interaction between zeolite minerals and free lime as well as secondary reactions between zeolite minerals and products of hydration.
The increased contents of MgO does not result in the negative phenomena. In three day samples hard-
ened in water it practically interacts with water as a result of high activity.
Quantity of zeolite. % 16
250
Specific surface, m2/kg
Quantity of zeolite, %
Specific surface, rrrtkg
Fig. 1 - The influence of the additive of zeolites on durability of mineral cement: 1 - hydraulic lime, 2 -romancement
As a result, romancement with durability 29 MPa and strong hydraulic lime with durability up to 22
MPa have been received from artificial mixtures of dolomite carbonate rocks and clay.
Conclusion
The expediency of using low stable hydraulic mineral cements of local raw resources with the extended interval of changing the mineral and chemical structure in production has been established.
Independently of MgO contents in carbonate -clay raw material it is possible to receive low stable hydraulic mineral cement by adjusting the temperature, duration of high temperature treatment of raw material and the ratio between carbonate and clay component.
Different mode of high temperature treatment makes it possible to receive hydraulic lime with durability no less than 12 MPa and romancement- no less than 20 Mpa
The possibility to reduce energy to 20% owing to temperature decrease and the duration of high tem-
perature treatment of raw material in comparison with traditional technologies has been shown.
It is also shown that the significant effect in using low stable hydraulic mineral cement is achieved by adding into them the zeolites from blast furnace as the additives.
References
1. Yung V.N. Introduction in technology of cement of M.: Gosstroiizdat, 1938.-404p.
2. Shokh K. Building mineral cement substances.Tr. from German. Part 1.-M.: Gosstroiizdat, 1934.-303p.
3. VoljenskiyA.V., Burov Yu.S., Kolokolnikov V.S. Mineral cement substances. - M.: Stroiizdat, 1979.-476p.
4. Vutt Yu,M., Sychov MM., Timashev VV.Chemical technology of mineral cement substances. - M.: Vysshaya shkola, 1976, 450p.
5. Pashenko A.A,, Serbin V.P., Starchevskaya Ye.А Mineral cement materials.., Kiev; Vysshaya shkola, 1985, 440p.
6. Butt Yu.M., Duderov G.N., Matveev М.А.General technology of silicates. M.: Stroiizdat, 1976.-600p.
© N. S. Shelihov - docent, Kazan State University of Architecture and Engineering, shelihov@kgasu.ru; R. Z. Rakhimov - professor, Kazan State University of Architecture and Engineering, rahimov@ksaba.ru; R. R. Sagdiev- assistant, Kazan State University of Architecture and Engineering ruslan-kgasu@yandex.ru; O. V. Stoyanov - professor, Kazan National Research Technological University, Department of Plastics Technology, ov_stoyanov@mail.ru.
© Н. С. Шелихов - канд. техн. наук, доцент КГАСУ, shelihov@kgasu.ru; Р. З. Рахимов - д-р техн. наук, профессор, зав. каф. строительных материалов КГАСУ, rahimov@ksaba.ru; Р. Р. Сагдиев - канд. техн. наук, ассистент КГАСУ, ruslan-kgasu@yandex.ru; О. В. Стоянов - д-р техн. наук, профессор, зав. каф. технологии полимерных материалов КНИТУ, ov_stoyanov@mail.ru.
