SU1167164A1 - Method of producing portland cement clinker - Google Patents

Abstract

A method for producing a portland clinker, including the preparation and firing of the raw mix in a rotary kiln with subsequent grinding of the clinker, is characterized in that, in order to intensify the process of mineral formation, improve the hydraulic activity of the clinker and the corrosion resistance of the cement, the mix of the start of the process, the start of the process, the start of the process, the start of the process, and the start of the set. forming a eutectic oxide-salt melt in the temperature range 900-1200C with a viscosity of 0.01-0j03 Pa-s in an amount of 10-25%, ppm of clinker mass. (L

Description

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The invention relates to the production of cement, and in particular to methods for the production of portland cement clinker in a rotary kiln and can be used in the construction materials industry.

The purpose of the invention is to intensify the process of mineral formation, increase the hydraulic activity of clinker and corrosion resistance of cement.

Preliminary mixing of the basic raw material charge with oxide-salt contributes to the appearance of the first melt droplets already at a temperature of about 500 ° C.

The compositions of the salt compositions are given in table. one.

Complete melting of the salt composition occurs at a temperature of approx. At the same time, the viscosity of the salt melt decreases to 0.005-0.010.

The presence of mineralizers such as chlorides, fluorides, and sulfates in the oxide mixture leads to a melting point of the melting point of the matrix melt. Simultaneously

The matrix melt oxides begin to dissolve vigorously in a low-saline melt. CaO dissolves in the amount of 12-15% SiO2, and FejOj in the amount of .1%. The resulting oxide-salt melt is characterized by 15-20 times lower viscosity values (0.01-0.08 Pas). The total amount of the liquid phase in the clinker, depending on the salt composition, is 10-25% by weight of the clinker. .

The combined presence of chlorides, fluorides, and sulfates in the mixture leads to a decrease in the melting point of the melt. Along with this, the temperature of CaCO decarbonization decreases. and education. If the oxide-salt melt is formed at a temperature below, the solid-phase reaction of formation of C-S does not have time to go through and the system dissolves CaO and SiO in the liquid clinker phase, which, in turn, inhibits the formation, and, ultimately, CjS. At the same time, the process of mineral formation slows down, the hydraulic activity of the obtained clinker and the corrosion resistance of cement decrease.

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If, however, the oxide-salt melt appears at a higher temperature, then due to the large time interval since the decarbonization of CaCO and the formation of C; S, before their partial or complete dissolution in the formed liquid phase, recrystallization occurs, growth and compaction of CaO and Cg3 grains. This leads to a slowdown in the dissolution and crystallization reactions of both CaO and C ,,, S, as a result of which the speed of the clinker formation process is reduced, which causes a decrease in the performance of the rotary kiln.

The resulting oxide-salt melt should have a viscosity of 0.010, 08 Pas. With a lower viscosity of the liquid phase, the rate of dissolution of CaO will significantly exceed the rate of formation and crystallization of C-S, with the recrystallization of CaO and CjS through the melt, which slows down the whole mineralization process. When the viscosity of the oxide-salt melt is more than 0.08 Pa, the rate of dissolution of calcium oxide and dicalcium silicate is slowed down, which also slows down the mineralization process. If the resulting oxide-salt melt has a viscosity of 0.01-0.08 Pa. S, then the dissolution rate of CaO and C-S corresponds to the rate of formation and crystallization. At the same time, acceleration of the mineral formation process is observed, the quality of cement based on this clinker is improved.

The oxide-salt melt in the clinker granule should be at least 10%. With a lower content of the liquid phase is not enough for the normal course of the process of liquid-phase sintering. When the melt content is less than 10%, diffusion from the surface of the solid is difficult, CaO and C.3 dissolve very slowly, which significantly slows down the process of alito formation.

When over 25% of an oxide-salt melt is formed, phase separation of oxide and salt melts occurs, which leads to deterioration of the material granulation in the furnace, clinker dusting occurs, and the density drops.

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honest cement, there are welds and ring formation.

Example s. According to any of the. of known methods, for example, on dry preparation, two raw materials are prepared: I — yo, co-basic, consisting of carbanate and clay components, taken in appropriate quantities; K - eutectic oxide-salt (Table 2). The oxide-salt charge is a mixture of slag and salt waste from various chemical industries.

The ratio of the main slag: salt composition is presented in table 2,

Then the raw material mixtures I and K are mixed in a ratio that ensures the production of clinker with a CN of 0.92-0.94 and n 2.0-2.3. Carefully homogenized, zoned mixtures (Table 2) are preformed under a pressure of 5.0 Iffla. The obtained briquettes are placed in a laboratory furnace and are calcined therein according to a given regime at 1250-1300 C. At such temperatures, sintering consumes about 4000 kJ / kg clinker for firing. Cooling briquettes quick on the air. The resulting clinker is ground to the specific surface of VA 3900 cvfjr. The ethyl glycerate method in all samples determines the amount of unbound calcium oxide and, based on the data obtained, calculates the degree of binding of calcium oxide to minerals. Mechanical tests were carried out on 4x4x16 cm beams prepared from a cement-sand mortar with a composition of 1: 3 (GOST 10178-76).

The test results are presented in Table. 3

Charges are also prepared by simultaneous mixing of lime, clay components, basic slag, and salt composition (examples 13 and 14 and

tabl; 2). The clinkers thus obtained have lower strength properties than the clinker of the proposed method. The rate of mineral formation in the resulting clinkers is lower, as evidenced by the results of the determination of unbound CaO in minerals (Table 2). With separate preparation of the charge, followed by their reduction before serving. in the rotary kiln, by firing and grinding, the clinker obtained by intensifying the processes of mineral formation |

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and improving the quality of cement is achieved by selective action of mineralizers on various components of the raw mix. In Example 1, the temperature of formation of the oxide-salt melt is lower than that of the proposed method, instead of, therefore, the compressive strength of the obtained cement decreases. In example 12, on the contrary, the temperature is higher, this also leads to a drop in strength, due to poor pregrection of the clinker grains. In examples 1, 3, 10, 12, the amount of eutectic oxide-salt melt that is formed is outside the scope of the invention. The clinker containing less than 10.00 and f-more than 25.90% of the melt is characterized by a lower hydraulic activity. In examples 1, 3, the viscosity of the oxide-salt melt is greater than the proposed method (0.147 and 0.214 Pa.s, respectively), which leads to a decrease in strength indicators. In example 10, the oxide-salt melt is characterized by a low 1 | (0.008 Pa.c), this also leads to a-. lower strength characteristics.

The resulting clinkers were also tested for corrosion resistance, the test results are given in table. four.

The durability coefficient is calculated as the ratio of the average compressive strength after aging in an aggressive solution and the average compressive strength of samples of the same cement while keeping them for the same period in drinking water. The results of the corrosion resistance test (Table 4) show that for cements that hardened in various aggressive solutions, no strength loss was observed compared to the control one (Example 15), therefore, it can be argued that the cements obtained by the proposed method are corrosion-resistant.

The results of the determination of the coefficients of corrosion-resistant cements obtained according to the invention (example 7) with cement obtained from clinker No. 13, which is obtained on the basis of the raw materials of the simultaneous grinding of all raw materials, show that the cements obtained by the previous method have a higher corrosion resilience. The preliminary mixing of the batch charge with the eutectic oxide-salt composition leads to a decrease in the temperature of formation of the oxide-salt melt and, consequently, the temperature of the completion of the blade | g formation process from 1450 to 1250-1300 C. The salt melt is evenly distributed in the oxide, intensifies the process of dissolving calcium oxide and the formation of Ct.S., j646 Thus, during preliminary mixing, before feeding into the rotary kiln, the raw mix with the charge, forming in the temperature range 900-1200C cal oksidnosolevoy melt with a viscosity of 0,010, 08 Pa.s in an amount of 10-25% by weight of clinker observed highest speed clinkering process obuslavlivakltsa absence of free calcium oxide in grains clinker. Cements obtained from these clinkers are characterized by increased compressive strength by 10.1-11.2 MPa after 28 days of curing. Table

table 2

CaSO -CaCl, -BaCl

CaSO -CaCl2-BaCl, j.

CaSO -CaClj-BaCl CaSO -CaCl -BaClj

MgCl -CaCl MnSO -CaSO

MnSO -CaSO

Claims (1)

METHOD FOR PRODUCING PORTLAND CEMENT CLINKER, including preparation and burning of the raw material mixture in a rotary kiln followed by grinding clinker, characterized in that, in order to intensify the process of mineral formation, increase the hydraulic activity of clinker and corrosion resistance of cement, the raw mixture is preliminarily fed into the rotary kiln charge, forming in the temperature range 900-1200 ^e C eutectic oxide-salt melt with a viscosity of 0.01-0.03 Pa * s in the amount of 10-25% 3 _{g of} mercury clinker mass. SU .... 1167164 1 11