EA033588B1 - Raw material mixture for producing portland cement clinker - Google Patents

Abstract

The invention relates to the industry of construction materials, in particular raw mixtures used to produce Portland cement clinker. A mixture of raw materials is provided to produce Portland cement clinker that includes limestone, tephritobasalt, coal production waste and lead slag waste, the mixture additionally containing sodium silicofluoride and process lignosulphanate to lower clinker calcination temperature and specific fuel consumption;, in the following component ratio, wt.%: tephritobasalt 9-13; coal production waste 7-23; lead slag waste 1-7; sodium silicofluoride 0.2-2.2; process lignosulphanate 0.2-0.5; limestone being the rest. Utilizing the proposed invention allows to reduce the consumption of fuel, increase the performance of the rotating furnace and cut the clinker prime cost.

Description

The invention relates to the construction materials industry, in particular, to compositions of raw mixes for obtaining low-energy Portland cement clinker.

A known raw material mixture for producing Portland cement clinker includes limestone and basalt, which in order to reduce the clinker calcination temperature and reduce specific fuel consumption additionally contains slag from copper smelting or lead production and CaCl ₂ in the following ratio of components, wt.%:

basalt 20-30 slag of copper smelting or lead production 1-5

CaCl ₂ 0.5-2.5 limestone rest.

(Innovation patent KZ No. 20516, class SB04/38, 2008. bull. No. 12).

A disadvantage of the known raw material mixture is the high firing temperature and high fuel consumption.

Closest to the invention is a raw material mixture for the production of Portland cement clinker, including limestone, tephritobasalt, lead slag, waste coal and sodium fluoride in the following ratio, wt.%:

tephritobasalt 9-13 lead production slag 1-5 coal waste 9-22 sodium fluoride 0.3-2 limestone rest.

(KZ patent for utility model No. 2211, class С04В 7/02, publ. 06/15/2017, bull. No. 11).

A disadvantage of the known raw material mixture is the high firing temperature and high fuel consumption.

The objective of the invention is to reduce the temperature of clinker firing and to reduce specific fuel consumption.

The problem is solved in that the raw material mixture for obtaining Portland cement clinker, including limestone, tephritobasalt, coal waste, lead slag, additionally contains sodium silicofluoride and technical lignosulfonate (LST) in the following ratio of components, wt.%:

tephritobasalt 9-13 coal waste 7-23 lead production slag 1-7 sodium silicofluoride 0.2-2.2 technical lignosulfonate 0.2-0.5 limestone rest.

Lead slag contains a significant amount of iron oxides 37-45%, which allows to increase the content of fluxes in the raw material mixture and to optimize the size of the silicate and alumina modules of the raw material charge. Lead slag contains up to 10-15% of zinc oxides, which have a strong mineralizing effect on clinker formation processes, allowing to reduce the clinker firing temperature and specific fuel consumption for firing. Sodium silicofluoride is an effective mineralizer of the cement clinker burning process and a thinner for raw sludge. At temperatures of 670-750 ° C, sodium silicofluoride in the presence of water decomposes into NaF and CaF ₂ . As a result, intensification of clinker burning occurs due to the action of two mineralizers. The mechanism of the diluting action of sodium silicofluoride is the decoagulating effect of monovalent Na ⁺ ions in raw sludge. In this case, monovalent Na ions replace divalent Ca ions and a loose coagulation structure with weakened bonds at the contact points is formed. Additives Na ₂ SiF ₆ release part of the adsorption-bound water in the sludge. There is a cation exchange of the Ca and Mg cations of the raw sludge to Na cations of the fluorine-containing salt, an increase in the charge of colloidal particles and deflocculation of clay aggregates. The mobility, fluidity of the system as a result of this increases sharply.

Technical lignosulfonate additives release part of the immobilized water. With the combined action of LFB with Na2SiF6, the effectiveness of the fluidizing action sharply increases and the moisture content of the sludge, while maintaining a given yield of 60-65 mm, decreases by 6-9%. Each percent reduction in sludge moisture while maintaining a given fluidity reduces specific fuel consumption by 1-1.5% and increases the furnace productivity by about 1.5%. When the organic part of the LST additive is burned out, additional heat is generated and fuel consumption is reduced for clinker burning. Coal waste contains 20-24% of coal. The lower water demand of the sludge and the presence of combustible particles of coal waste and LFD determine the saving of process fuel.

Highly active fluorine molecules have a destructive effect on crystal lattices

- 1,033588 raw material charge components. As a result of the action of Na ₂ SiF ₆ and zinc spinel contained in the slags of lead production, temperatures are reduced and the processes of dehydration and decomposition of clay minerals, decarbonization of CaCO ₃ are accelerated, the content of free silicon, aluminum, iron and calcium oxides ready to enter chemical interaction with the formation of new compounds. At lower temperatures and with a higher speed, solid-phase interactions in the raw material mixture occur, the temperature of the appearance of the liquid phase decreases, the properties of the clinker liquid phase - viscosity, surface tension, density - diffusion processes in the clinker melt are significantly improved and accelerated. Because of this, clinker formation processes are significantly accelerated, mineral formation reactions occur more intensively and at lower temperatures and end at 1250-1300 ° C. This helps to reduce the specific fuel consumption for clinker burning by 18-22% and allows to increase the furnace productivity.

Lead slag consists mainly of fayalite and melilite (up to 74% in total), in addition, it contains sulfides of iron, lead, copper (up to 2%), wustite (9-13%), zinc spinel (5-7%) glass (up to 10%).

Slag consists mainly of particles with a size of 0.25-2 mm.

Due to the significant content of silicon, aluminum and iron oxides, tephritobasalt completely replaces the clay component, and also partially or completely replaces the deficient corrective additive, pyrite cinders. Tephritobasalts are highly reactive igneous rocks that can reduce the clinker calcination temperature.

Tephritobasalt is the main effusive rock of the normal series, the most common of cainotype rocks, transitioning from tephritis (effusive analogues of alkaline gabbro) to basalts (effusive analogues of gabbro). By the content of silica and other oxides belong to the main rocks. This allows the use of tephritobasalt as an aluminosilicate component of the raw material mixture and instead of an iron-containing corrective additive. The density of tephritobasalts is 2.0 g / cm ³ , the compressive strength is 47.6-195.8 MPa.

The structure of the rock is porphyry. Porphyry phenocrysts are represented by monoclinic pyroxene, plagioclase, olivine, biotite and magnetite. The fine-grained glassy mass is composed of brown decomposed glass and an alkaline mineral - analcime (NaAlSiO ₆ -H ₂ O). The voids and pores in tephritobasalt as a result of secondary hypergenic processes are filled with zeolite and calcite. The average mineral composition of tephritobasalts,%: pyroxene 45-55; mica clay minerals 2540; plagioclase, volcanic glass, olivine, hornblende, zeolite, ore minerals (magnetite, apatite, hematite, goethite) 2-3; calcite 2-3. The chemical composition of the raw materials is given in table. 1.

Table 1. The chemical composition of the raw materials

Raw materials and waste Chemical composition, wt.% SiO ₂ A1 ₂ 0h Re ₂ 0z CaO MgO SO ₃ ppp the amount Limestone 3.87 1,04 0.57 52.83 0.88 0.10 40.71 100.00 Cinder 17.81 4.25 62.23 4.21 3.71 - 7.79 100.00 Lead slag 25.94 6.44 37.25 14.71 6.15 0.04 0.1 90.63 Tephritobasalt 45.54 10.7 8.53 10.66 6.95 0.2 7.92 90.50 Coal waste 55.50 10.6 2.01 3.21 0.7 0.79 24.08 96.89

Raw mix preparation example

The components of the raw mixture are ground in a laboratory ball mill to a residue on sieve No. 008 - 9-12%. Ground components in the ratio, wt.%:

tephritobasalt 9-13 coal waste 7-23 lead production slag 1-7 sodium silicofluoride 0.2-2.2 technical lignosulfonate 0.2-0.5 limestone rest.

mixed in the mixer for 30 minutes

The fluidity of the raw sludge was determined using Neginsky TN-2 fluidity meter. To determine the amount of moisture reduction, the sludge fluidity was reduced to a standard 60 mm by reducing the amount of water added to the dry sludge sample and the percent reduction in water dosage was calculated.

To study the firing processes, the obtained dry raw mixture was moistened to a moisture content of 8-10%, pellets of 020 mm size, 10 mm high were pressed. After that, the tablets were dried at 100 ° C for 1 h and calcined in an electric silica furnace at temperatures of 1250, 1300, 1350,

- 2 033588

1400 ° C with exposure at maximum temperature for 30 minutes The completeness of the clinker formation process was controlled by the content of CaO _freedom . The quantitative content of CaO in the clinker _svob determined ethyl-glitseratnym method. The uniformity of the change in the volume of cement was determined by boiling the cakes from the cement paste.

The compositions of the raw mixes, a decrease in their moisture content, reactivity and specific fuel consumption for clinker burning are given in table. 2.

Table 2. The composition of the raw mixes and the results of their testing

Example Raw mix The composition of the raw mix,% KN Modules Limestone Ephritobasalt Coal waste Lead slag .¾ s to? Z Technical lignosulfonate NaF η R 1 2 3 4 5 6 7 8 9 10 AND 12 1 According to the prototype 75.92 10.55 10.66 2,57 - - 1,0 0.90 2,5 1.27 2 Option 1 74.56 11.47 11.48 1.49 0.8 0.3 0.85 2.7 1.51 3 Option 2 75.75 10.93 10.93 1.39 1,0 0.5 0.90 2.7 1,52 4 Option 3 75.01 9.58 9.58 4.63 0.2 0.3 0.92 2.2 0.99 5 Option 4 76.38 10.25 10.15 2,52 0.7 0.5 0.92 2,3 1.28 6 Option 5 75.09 10.05 10.24 2.62 2.0 0.5 0.92 2,3 1,08 7 Option 6 79.11 9.19 9.09 2.60 0.1 0.1 0.98 2.2 1.68 8 Option 7 75.09 10.06 9.73 2.62 0.1 0.2 0.95 2.2 0.97 9 Option 8 78.01 6.1 9.98 4.71 2,3 0.1 0.94 2.2 0.99 10 Option 9 71.69 14.2 9.49 2.62 oh 1 0.7 0.91 2.2 0.97 Example The moisture content of the sludge,% Humidity reduction,% The content of CaO _CBO b.% At firing temperature ° C The test for uniformity of volume changes at t firing, 1400 ° C Specific heat consumption, kJ / kg clinker Specific fuel consumption for firing, kg / t clinker 1250 1300 1350 1400 1 thirteen 14 fifteen 16 17 19 20 21 22 1 34 0 18.7 9.85 1,6 0.52 withstood 4933 168.8 2 29th 5 1.9 0.6 0.3 0 withstood 4180 142.5 3 27 7 3.8 1.8 0.4 0.12 withstood 3950 134.7 4 29th 5 4,5 3.6 2,3 0.42 withstood 4120 140.5 5 26 8 3.2 1.8 0.7 0.1 withstood 3970 135.4 6 25 9 2,3 1,1 0.5 0 withstood 3910 133.3 7 32 2 16.8 12,4 5,6 3,5 did not take it 5498 187.4 8 32 2 14.2 10.5 5.1 2.7 did not take it 5216 177.8 9 27 2 2,3 1,2 0.6 od withstood 5032 171.5 10 27 7 16.9 12.8 6.2 2.1 withstood 4930 168.1

Options for raw mixtures 1-5 are optimal.

During the clinker firing, Na ₂ SiF ₆ and lead production slags have a mineralizing effect, technical lignosulfonate together with Na ₂ SiF ₆ have a thinning effect and reduce sludge moisture by 6-10%, the firing temperature decreases from 1400 to 1250-1300 ° C, the content CaO _freedom is reduced, the specific heat consumption for firing 1 kg of clinker is reduced from 4933 kJ / kg (control mixture) to 3910-3950 kJ / kg, the specific fuel consumption is reduced from 168.8 to 133.3134.7 kg per ton of clinker.

The specific fuel consumption is reduced due to a decrease in sludge moisture from 34 to 2526%, lowering of the clinker burning temperature from 1400 ° C in the prototype to 1250-1300 ° C in the proposed raw material mixtures.

This will increase the productivity of the rotary kiln and reduce the cost of clinker.

Claims (1)

CLAIM The raw material mixture for the production of Portland cement clinker, including limestone, coal waste containing 20-24% of coal, tephritobasalt and lead slag, characterized in that it additionally contains sodium silicofluoride and technical lignosulfonate in the following ratio, wt.%: Tephritobasalt - 9 -thirteen; coal waste - 7-23; lead production slag - 1-7; sodium silicofluoride - 0.2-2.2; technical lignosulfonate - 0.2-0.5; limestone - the rest.