RU2285676C1 - Power-saving method of production of the portland-cement clinker - Google Patents

Abstract

FIELD: construction materials industry; the power-saving methods of production of the Portland-cement clinker.

SUBSTANCE: the invention is pertaining to production of the cement-cement clinker by the dry, semidry, wet and combined methods. The power-saving method of production of the cement-cement clinker provides for the sintering in the rotating furnace at the temperature of 1380°C-1450°C of the technological mixture of the limestone and the argillaceous material - the sediment of the sewage-purification facilities - the sewage farm of the aeration station with the moistness from 8.0 % up to 90 % at the weight ratio of the limestone to the indicated sediment from 1:0.4 up to 1:1.3. The technical result is the saving of limestone, fuel and power at production of the clinker, cost-saving of production of the Portland-cement, solution of the ecological problems of the areas due to utilization of the sediments of the sewage-purification facilities in the wide range of the moistness.

EFFECT: the invention ensures the saving of limestone, fuel and power at production of the clinker, cost-saving of production of the cement cement, solution of the ecological problems of the areas.

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Description

The invention claimed as a patent relates to the field of industrial production of Portland cement clinker using dry, semi-dry, wet and combined methods for the disposal of industrial waste-sediment from treatment plants (1-11).

Known methods for the production of Portland cement clinker are carried out by sintering a mixture of limestone and clay in an approximate ratio of 3: 1, respectively, in rotary kilns at a temperature of 1380-1450 ° C. The clinker formed after sintering is crushed, and then mixed in different proportions with crushed slag, ash, pozzolan, gypsum and a number of other additives. In some cases, the production of cement clinker in Europe is carried out by sintering limestone with sludge from sewage treatment plants previously dried at a temperature of 85 ° C.

The above methods for the production of cement clinker have significant drawbacks, associated primarily with a high consumption of coolants. The most economical of them is the dry method of production of cement clinker. According to (5), 3218 kJ of heat are consumed for the production of one kilogram of clinker in a dry method.

The method of production of cement clinker used by ZAO Dakt-Engineering using limestone and dried sludge from sewage treatment plants, which has a calorific value of 11 thousand kJ per kilogram of sludge, therefore seems to be uncontested, since it allows to significantly reduce fuel consumption for its production. However, the use of dried sludge is a significant drawback of this method, since for its implementation it is necessary to remove water from wet sediments. To remove water from the sludge with a humidity of 71.0%, from which one ton of cement clinker can be produced, it is necessary to spend 4826157 kJ of heat, which is significantly higher than the heat consumption (3762000 kJ) required to produce one ton of clinker in the classical way. Thus, together with the costs of the construction and operation of the sludge drying plant, the economic efficiency of the method of producing Portland cement using dried sludge is sharply reduced.

The present invention eliminates the above-mentioned disadvantages of methods for the production of Portland cement and, in terms of economic efficiency, equalizes all methods of production of Portland cement clinker accepted in world practice.

The technical result of the invention is achieved in that an energy-saving method for the production of Portland cement clinker, including sintering in a rotary kiln at a temperature of 1380-1450 ° C of a technological mixture of limestone and clay material - sludge from sewage treatment plants - irrigation fields of aeration stations with humidity from 8.0 to 90% (wet sediment) with a weight ratio of limestone to the specified sediment from 1: 0.4 to 1: 1.3.

The paradox of the proposed method is that all the energy costs of producing Portland cement are compensated by the energy capabilities of the organic substances that make up the sediment.

The energy capacity of organic substances included in the sludge composition of sewage treatment plants, comprising about 50.0% of the mass of dry matter, reaches 11-19 thousand kJ per kilogram of sludge. This circumstance allows reducing the fuel consumption for the production of Portland cement clinker without the cost of drying the sludge and making alternative all the methods of its production accepted in world practice.

Precipitation of aeration stations is a fine (about 200 microns) clay product of a dark color with a total humidity of up to 90.0%. Precipitation from irrigation fields of different regions have humidity, which varies from 8.0 to 97.0%.

Sludge moisture is represented by water bound to the protein of sludge microorganisms (about 50.0%) and unbound water (about 20.0%), distributed in a volume free from the dry residue of the sludge.

A typical chemical composition of the components of the raw mix, which can be used for the production of cement clinker using sludge from aeration stations, is shown in Table 1.

Table 1 shows the calculated values needed to determine the composition of the process mixture. Table 2 shows the estimated norms of the raw components of the technological raw mix necessary for the production of one ton of cement clinker from limestone and loam, limestone and sludge from aeration stations.

From these tables it can be seen that the production of one ton of cement clinker using sludge from limestone aeration stations requires 179 kg less than the production of one ton of clinker from limestone and loam by the classical dry method. From the data of Table 2 it is also seen that for the production of one ton of cement clinker, 1976 kg of water must be removed from the technological mixture. The proposed method removes water from the technological mixture by heating it with heat, which is released during the combustion of organic sediment substances, the calorific value of which is estimated at 11000-18750 kJ / kg. As can be seen from Table 3, this amount of heat is sufficient to remove water from the process mixture and reduce the flow of heat necessary for sintering the mixture into clinker. A comparison of the results shown in Table 3 with the known literature data (5) is given in Table 4. Analysis of the data in Table 4 shows that the production of Portland cement clinker using sludge from aeration stations reduces the energy consumption necessary for sintering the process mixture by releasing it into the system heat sludge from the combustion of organic substances. Despite the high humidity of the technological mass, exceeding the humidity of the technological mixture used in the wet method of production of Portland cement clinker (30.0-40.0%), the energy consumption for the production of clinker is lower than in the production of its dry method.

An expert assessment of the physicotechnical and mechanical properties of Portland cement clinker obtained from a technological mixture of limestone and wet sludge from aeration stations is given in Table 5.

The results of the expert assessment clearly show the possibility of obtaining high-quality cement clinker by the proposed method. The introduction of the process into the industrial production of Portland cement clinker will solve the environmental problems of the regions and obtain building material that meets GOST 23464-79.

Real heat savings at an enterprise with a capacity of 730000 tons of Portland cement clinker can be up to 730 thousand Gcal per year due to fuel savings.

The calculations and test results given in the application of samples of cement clinker obtained by calcining a technological mixture of limestone and wet sludge from aeration stations make it possible to clearly formulate the claims.

Table number 1
The chemical composition of raw materials and clinker Raw Mix Components The chemical composition of the components of the raw mix, wt.% Derived Values M _o M _a SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ Cao MgO p.p.p. Basicity module Activity module one 2 3 four 5 6 7 8 9 Limestone 0.2 0.25 0.2 51.0 3.0 43.5 - - Loam 71.82 13.62 3.99 1.02 0.9 3.4 - - Ash sludge aeration stations 46.6 12.0 9.4 9.3 1.06 - - - Clinker 22.0 6.0 3.0 63.0 1.5 - 2.08 0.27 Table number 2
Consumption rates of raw materials for the production of 1000 kg of Portland cement clinker, depending on the method of its production Raw components of the process mixture and derived quantities Method of production and expenditure rates of raw materials, derived quantities, kg Dry way The method with sediment aeration stations one 2 3 Limestone 1235 1056 Residue after calcining limestone 697.94 597.6 Loam 306.32 - Residue after calcining loam 295.9 - Process weight 1541.61 3880.9 * Precipitation of aeration stations - 2825.1 ** Sediment water - 1975.1 Dry sediment - 849.4 Sludge ash - 424.7 The relationship between limestone and the mixture component 4.03 0.374 The ratio between the component of the technological mixture and limestone 0.25 2.7 * - Humidity of the technological mixture 50.90%
** - Humidity of sludge from aeration stations 71.00%

Table number 3
Basic physico-chemical data and standard consumption values for the quantities required for the production of 1000 kg of Portland cement clinker using the method using sludge from aeration stations Consumption rates of raw materials and the name of physico-chemical quantities Dimension Value one 2 3 Limestone consumption kg 1056 Sediment consumption kg 2826 Sediment water kg 1976 Dry sediment kg 849.4 Mass of organic matter kg 425 Calorific value of dry sediment kcal / kg 2640-4500 kJ / kg 11000-18750 Heat of vaporization kcal / mol 10.519 kJ / mol 43.96 The amount of heat required to remove water from the process mixture kcal / 1976 kg 1154583 kj / 1976kg 4826-157 The amount of heat released during the combustion of dry sludge kcal / 849 kg s. about* 2242495-3822435 kJ / 849 kg s about. 9343730-15926812 The amount of heat released into the system after removing water kcal / 849 kg s.o. 1087912-2667852 kJ / 849 kg s.o. 4517573-111000655 Liquid fuel consumption kg 115 Calorific value of liquid fuel kcal / kg 10000-11000 kJ / kg 41800-45980 Amount of heat released during fuel combustion kcal / 115 kg 1150000-1265000 kj / 115kg 4807000-5287700 Enterprise performance t. clinker / year 730000 Fuel consumption using sediment from aeration stations kg 6-115 * so. - dry sediment

Table number 5
Expert assessment of the physical, technical and mechanical quality parameters of Portland cement clinker produced using precipitation of aeration stations at a temperature of 1380 ° С-1450 ° С * Cement clinker sample number ** Specific surface area,
cm ² / g Normal density,% Spreadability, mm Dates, hours, set The tensile strength of beams, MPa, with bending and compression in age, day Start the end 3 7 28 one 2 3 four 5 6 7 8 9 one 2680 26.2 110 3 ³⁰ 5 ⁴⁰ 1.9 / 9.7 3.6 / 28.5 4.8 / 38.7 2 2620 24.2 125 3 ³⁰ 6 ²⁰ 2.95 / 13.2 4.9 / 31.5 5.9 / 42.0 3 2690 25.4 120 3 ²⁰ 5 ⁵⁰ 2.26 / 12.5 3.7 / 30.0 5.2 / 39.1 four 2650 26.1 110 3 ²⁰ 5 ⁴⁵ 2.5 / 12.7 3.6 / 28.5 5.5 / 41.0 5 2700 24.8 115 3 ²⁵ 5 ⁵⁵ 2.0 / 11.5 3.8 / 29.5 5.3 / 40.5 6 2695 25.2 112 3 ³⁵ 5 ⁴⁰ 2.9 / 12.8 3.9 / 31.0 5.2 / 40 7 2625 26.2 120 3 ³⁰ 5 ⁵⁰ 2.6 / 13.0 4.9 / 31.5 5.8 / 41.5 8 2680 25.5 110 3 ²⁵ 6 ⁰⁰ 2.8 / 12.9 4.0 / 31.0 5.1 / 39.5 9 2705 24.8 115 3 ³⁰ 5 ⁵⁵ 2.85 / 13.0 4.1 / 32.0 5.0 / 39.8 10 2710 25.2 120 3 ³⁵ 5 ⁵⁰ 2.9 / 13.1 3.6 / 29.0 4.9 / 40.0 * The physical density of the samples, g / cm ³ varies in the range 3.0-3.2; bulk density in loose and compacted state averages 1.15 g / cm ³ and 1.5 g / cm ^3, respectively
** Samples 1-3 are prepared from a raw mix with a ratio of limestone: sediment of treatment plants 1: 0.374, samples 4-6 - with a ratio of 1: 1, samples 7-10 - with a ratio of 1: 1.3.

The list of scientific, technical and patent literature used in the patent search of the invention: Energy-saving method for the production of Portland cement clinker No. Author Title Edition one Venua M. Technological schemes of cement production M., "Building Materials", 1980 2 Gorchakov G.I. Construction Materials M., 1986 3 Cement and its application No. 1 2004 four Taylor, Hal F. Cement chemistry M., "World", 1996 5 Goldstein L.Ya. Cement production through industrial waste disposal L., "Stroyizdat", 1985 6 Shevtsov A.M. Patent No. 2065845 1996 7 Shevtsov A.M. Patent No. 2074134 1997 8 Butt Yu.M., Volkonsky B.V., Egorov G. B. Cement Handbook L., 1980 9 Verdiyan M.A., Bobrov D.A., Verdiyan A.M. Scientific Foundations of Cement Technology M., 2000 10 Structure and performance of cements London, New York, 1983 eleven My Moscow. Magazine of metropolitan life, No. 7 2004

Claims (1)

An energy-saving method for the production of Portland cement clinker, including sintering in a rotary kiln at a temperature of 1380-1450 ° C of a technological mixture of limestone and clay material - sludge from sewage treatment plants - irrigation fields of aeration stations with humidity from 8.0 to 90% with a weight ratio of limestone to the specified sludge from 1 : 0.4 to 1: 1.3.