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Nimchik Aleksey Grigorevich, candidate of technical sciences of the laboratory of chemistry of silicate, Institute of general and inorganic chemistry Academy of Sciences of Uzbekistan, Tashkent Usmanov Hikmatulla Lutfullaevich, candidate of technical sciences, senior scientific employee of the laboratory of chemistry of silicate Institute of general and inorganic chemistry Academy
of sciences of Uzbekistan, Tashkent Kadyrova Zulayho Raimovna, head of laboratory chemistry of silicate, doctor of the chemical sciences, professor, Institute of general and inorganic chemistry Academy
of sciences of Uzbekistan, Tashkent E-mail: [email protected].
PROPERTIES OF CLINKERS AND CEMENTS, OBTAINED ON THE BASIS OF FLOTATION OF WASTE OF MINING PROCESSING ENTERPRISES
Abstract: The possibility of obtaining Portland cement clinkers based on flotation waste from mining and processing plants LPP, CPP, FPP at Tfejng 1380-1430 oC has been established, and the processes of hydration and hardening of the obtained cements and their physicomechanical properties have been studied.
Keywords: flotation waste, clinker, hydration, Portland cement.
The possibility of using flotation wastes of mining and lead processing plants (LPP), copper processing plants (CPP) processing industries as a clay component for cement produc- and fluorite processing plants (FPP). tion was considered in many papers [1-3], in which the au- Calculations of the chemical composition of clinkers were
thors noted great prospects for using waste as clay substitutes carried out at a constant silicate module of n = 2.1 and a vary-and activating clinker formation processes in the solid phase ing saturation coefficient SC = 0.7-0.95. On the basis of the and with the presence of a liquid phase. calculation of the raw mix according to the generally accepted
We have studied the properties of clinkers and cements method [4], mixtures with different contents ofwaste wastes synthesized on the basis of flotation wastes of mining process- were prepared (see table). ing plant of the Almalyk MMC, namely, flotation wastes of
Table 1.- The chemical composition of raw mixtures of Portland cement clinker
№ Name of composites SC n SiO2 Fe2o3 CaO MgO SO3 R2O LOI
1. Mixture on the basis LPP 0.8 2.1 14.85 3.33 3.61 41.45 3.02 1.47 0.81 31.70
2. Mixture on the basis LPP 0.9 2.1 13.91 3.18 3.57 42.06 2.89 1.38 80.77 32.31
3. Mixture on the basis CPP 0.8 2.1 15.11 3.33 3.83 42.10 0.85 1.15 1.09 33.21
4. Mixture on the basis CPP 0.9 2.1 14.18 3.13 3.61 41.30 0.86 1.13 1.10 33.77
5. Mixture on the basis FPP 0.8 2.1 15.90 1.88 5.84 41.54 0.91 0.26 0.48 32.52
6. Mixture on the basis FPP 0.9 2.1 14.00 1.78 5.34 42.50 0.92 0.24 0.45 33.26
The firing of raw mixtures was carried out in a salt fur- The chemical composition of the clinkers obtained (table 2) nace in an oxidizing environment at Tfcing-1350-1450 °C. shows the compliance of the calculated and actual.
Table 2.- The chemical composition of clinkers on the basis of fleet waste (calculated and practical)
№ Name Chemical composition,%
SiO2 Fe2O3 CaO
1 2 3 4 5 6
Clinker based LPP
1. - calculated 20.512 4.69 5.27 62.01
- practical 1.12 4.27 5.31 61.96
1 2 3 4 5 6
Clinker based CPP
2. - calculated 21.41 4.73 5.45 63.36
- practical 20.66 4.83 5.42 63.11
Clinker based FPP
3. - calculated 21.99 2.68 7.94 63.66
- practical 21.22 2.44 8.21 62.68
The study of the physicochemical properties of the clinkers obtained was carried out by X-ray phase, petrographic and alcohol-glycerate methods. Using the alcohol-glycerate method, it was found that the total absorption of CaO in raw
' 1 tree
mixtures is within 1370-1420 s at 30 minutes exposure at a given temperature. The lower temperature of the completion
of the clinker formation process, T 1350-1375c is inherent
L 1 firing
in FPP flock waste clinkers, which was mentioned in work [5] due to the mineralizing role ofCa fluoride, which stimulates the formation of the liquid phase at earlier stages of solid-phase synthesis, which in turn activates both the decarbonization of the carbonate component and the formation of clinker minerals.
Figure 1. X-ray of clinkers on the basis of fleet waste:
1. LPP with SC = 0.8; 2. 3. CPP with SC = 0.8; 4. 5. FPP with SC = 0.8; 6. X-ray phase analysis (Fig.1) of the clinkers under study revealed well-crystallized minerals in all clinkers; alite d = 0.303, 0.277, 0.274, 0.259 nm, belite d = 0.287, 0.279, 0.260 nm, tricalcium aluminate d = 0.270, 0.191, 0.155 nm. Small
LPP with SC = 0.9; CPP with SC = 0.9; FPP with SC = 0.9; changes in the form of x-ray clinkers indicate the identity of the phase composition of the clinkers.
Data from petrographic studies suggest that the presence of various silica components in the raw material mixtures, as
well as the presence of non-ferrous metals in them, do not have a significant effect on the composition and crystallization of minerals. The main crystalline phase of the clinkers obtained is alite, and its crystals are of the same type and
Table 3.- Mineralogical composition of clinkers on
are represented mainly by hexagonal plates measuring 7-50 microns. The amount of alite, determined by the petrographic method, is 50-60% in all clinkers, which is consistent with the calculated data of the mineralogical composition (Table 3).
the basis of fleet waste (Estimated and practical)
№ Name Mineralogical composition,%
C3S C2S C3A C4AF
Clinker based LPP
1. - calculated 62.01 16.36 3.51 16.02
- practical 63.21 16.27 3.48 16.81
Clinker based CPP
2. - calculated 59.31 21.25 3.26 16.57
- practical 62.31 18.97 3.41 10.81
Clinker based FPP
3. - calculated 60.11 15.76 3.00 21.13
- practical 59.61 17.21 2.86 20.51
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Figure 2. X-ray of cements with SC = 0.9
1. LPP - 1day. 2. LPP - 28 day.
3. CPP - 1day. 4. CPP - 28 day.
5. FPP - 1day. 6. FPP - 28 day.
According to the crystallization of alite, clinker with SC = 0.9 is allocated to the magnitude and quality of the crystals on the basis of the LPP flotation waste due to the presence of acid oxides and high basicity of the raw mix.
The presence of CaF2 (0.8-1%) in the raw mix with FPP flotation waste produced clinker with a low Tfiring and good mineralization.
Chemical, petrographic, thermographic, and X-ray phase analysis methods were used to study the hydration of the clinkers obtained and, on their basis, it was found that it is characterized by the stadiality of mineralization of new phases that is usual for Portland cement.
Thus, in the initial periods of hardening, X-ray phase (Fig. 2) and petrographic methods indicate the formation of coarse-grained crystals of Ca oxide hydrate with d=0.493, 0.310, 0.263 nm and ettringite grains 3CaO Al2O3 3CaSO4 31H2O with the main diffraction maximum with d = 0.958 nm, the formation of which is more intensively for cements with SC = 0.9, as well as small flaked crystals of calcium hy-droaluminate 3CaO Al2O3 CaCO3 11H2O with a diffraction maximum of d = 0.780 nm.
Calcium hydroaluminate is the main mineral providing the initial strength of the cement stone on the first day of hardening and is formed in large quantities in clinkers capable of giving a large supersaturation of the liquid phase in CaO-alitic clinker.
The mineral phases of ettringite and calcium hydrocarbonate are more pronounced in the clinker images with LPP and CPP and SC = 0.8.
In clinics with LPP, CPP, FPP 28 daily hardening, in addition to the previously identified minerals, the formation of calcium hydrosilicate (1.7-2.2) Cao SiO2 2H2O d = 0.307 is noted; 0.280; 0.183 nm, characterized by qualitative crystallization and being, as is well known, the main component of the strength of cement stone after 28 days of hardening. In this case, the quantitative formation of new crystalline phases prevails in the clinkers based on the flotation waste of LPP and CPP, which naturally depends on the mineralogical composition of the raw mixtures.
The results ofX-ray phase analysis and petrographic analysis are confirmed by the data of thermographic studies, as the dehydration of calcium hydrosilicate corresponds to the endothermic effect at 140-180 °C, which reaches a considerable amount after a day of hardening, and with an increase in the hydration period of all cements, this effect increases. On the thermograms of hydrated cements, the endothermic effect at 760-780 °C corresponds to the decarbonization of CaCO3, which is formed by the interaction of hydration products with carbon dioxide of air. Characteristic for thermograms of all cements is that there is no significant difference in the process of their hydration. The data of chemical analysis of hydrated cements (Table 4) also indicate an increase in the content of Ca(OH)2 by the 28th day of hardening.
in hardening cement paste (%)
Table 4. - The content of Ca(OH)2
Cement Terms of hardening (in days)
1 3 7 28 90 180 360
Cement LPP 4.9 6.5 9.2 13.4 12.9 12.4 11.9
Cement CPP 5.0 6.6 9.3 13.5 13.0 12.0 11.9
Cement FPP 4.7 6.3 9.1 13.2 12.7 11.8 11.5
The decrease in the Ca(OH)2 content with an increase in the hydration period (90, 180, 360) is due to the action of CO2. It should be noted that the nature of the change in the content of Ca(OH)2 in the hydrated cement is identical for all the samples studied.
The study ofthe process ofhydrolysis ofall cements (Table 5) showed that, reaching a maximum value after three days of hy-
dration, the concentration of CaO in solutions subsequently decreases somewhat. This can be explained by an increase in the degree of crystallization of the tobermorite phase.
The practical absence of differences in the content of Ca(OH)2 in the liquid phase of hydrated same time studied cements, characterizes a small difference in the phase composition of the products of their hydration.
Table 5.- The results of the study of the hydrolysis of cements
Cement CаО g/l
3 7 28 90 180
Cement LPP 1.404 1.328 1.245 1.075 1.000
Cement CPP 1.376 1.348 1.274 1.052 1.041
Cement FPP 1.306 1.284 1.247 1.044 1.191
As a result of the conducted research, the possibility of obtaining clinkers of optimal mineralogical and crystallo-graphic compositions based on the used flotation waste LPP, CPP, FPP as a silica-containing component of raw mixtures, at optimal conditions and firing temperature, was established.
The difference in the mineralogical composition of the FPP waste flooder for acid oxides makes it possible to use this
waste not only as a complete substitute for loess, but also as an additive with pronounced mineralizing properties.
Physical and mechanical tests of cements, ground with 4% gypsum, showed that they are not inferior in strength and time of setting (Table 6) to their factory counterparts with brand strength of 500.
Table 6.- The results of physico-mechanical tests of cements based on flotation waste
Name of cement Setting time, hour. Strength in MPa
Bending Under compression
starting ending 3 days 28 days 3 days 28 days
Cement LPP 1-45 3-15 2.7 5.2 31.7 58.02
Cement CPP 1-35 3-15 2.2 4.8 27.3 52.0
Cement FPP 1-45 3-20 2.1 4.3 19.5 50.0
Thus, the test results showed that the reactivity of raw lesser extent, FPP, is not inferior to natural silica-containing mixtures containing, as a silica waste, LPP, CPP and, to a raw materials.
References:
1. Mihaelyan V. G., Karapetyan I. A., Akopyan A. K. Investigation of the influence of rocks on the process of clinker formation // High Temp. chemistry of silicates and oxides // Proc. 6 All-Union. meeting - Len. 1988.- P. 348-356.
2. Akhmedov M. A., Ashirova D. A., Napolsky B. I. et al. Use of waste from secondary non-ferrous metals as additives to the raw material mixture during firing. Tr. Gos. VNII Cement prom. (Research Institute of Cement).- M.: 1990.- No. 99.- P. 70-78.
3. Zagorodnyuk L. Kh., Shchekina A. Yu., Shiryaev O. I. Waste enrich-ment of the mining industry in the production of building materials. Col-lected Materials 1-Int. scient. and practical conf.- M.: 2013.- P. 41-43.
4. Bobkova N. M. Physical chemistry of refractory non-metallic and silicate materials.- Minsk: High School. 2007.- 301 p.
5. Pashchenko A. A., Myasnikova E. A. The influence of CaF2 on the process of clinker formation in lime-basalt raw mixtures. Construction materials, products and dignity. equipment. 1983.- No. 6.- P. 11-13.
