CS241602B3 - Method of processing cement raw material - Google Patents

Abstract

The purpose of the invention is to replace some of the correction components used so far in the processing of cement raw materials. The stated purpose is achieved by completely or partially removing the resulting ash or solid waste from the technological process of clinker firing and using it as one of the correction components for the preparation of the raw material processed in this line, while the correction component is subsequently included in the entire process of chemical-technological treatment of the raw material.

Description

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KR&ČK0VÁ JITKA ing.i

PILOUS Jlfil ing.;

NEMECEK PETR;

KR&ČEK ZDENĚK ing.CSc,, PfiEROV

Cement raw material processing method

The purpose of the invention is to replace some of the correction components used so far in the processing of cement raw materials.

The stated purpose is achieved by removing the resulting ash or solid waste in whole or in part from the technological process of clinker firing and using it as one of the correction components for the preparation of the raw material processed in this line, with the correction component subsequently participating in the entire process of chemical-technological treatment of the raw material.

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The invention relates to an improved method of processing cement raw materials, the use of ash and solid waste generated during the combustion of inferior and waste solid fuels with a high ash content according to the basic Czechoslovak author's certificate No. 240675

The essence of the production of cement clinker according to the basic invention is that the thermal energy for sintering is obtained from a fuel with a higher calorific value compared to the fuel used for decarbonization, which is a fuel or combustible industrial waste with a calorific value above 5000 kJ.kg, but lower than the calorific value of the fuel for sintering.

There are known methods for producing cement clinker, in which finely ground solid fuel is used as a technological fuel, which is burned by burners in a rotary kiln or in an attached calciner, while the resulting ash, which contains a number of chemically bound oxides, becomes part of the processed raw material and subsequently participates in the formation of clinker-forming minerals.

«

These are mainly the following oxides:

CaO, - calcium oxide,

SiO ₂ - silicon dioxide, ^^2θ3 aluminum, ^ϊ ' ^θ 2°3 ~ iron oxide, which as additional components of the chemical-technological process can significantly affect the quality of the resulting product. Therefore, their total content, and thus essentially the amount of added ash, is always limited by the basic requirement of clinker quality.

The maximum ash content is close to 10%, calculated on the total amount of raw material, with a deviation of 2

241,602 ky from this value are given by proven operating practices, which ensure, in addition to the quality of the clinker, optimal trouble-free operation by preventing the formation of stickers when the temperature of the softening and melting point of the ash is exceeded, especially in cases where the fuel is burned in a separate calciner upstream of the rotary kiln»

At present, when methods are being sought to enable the use of lower-value fuels in the production of cement clinker, one of the basic problems is the comprehensive processing of all ash produced, the content of which increases with decreasing fuel calorific value, especially for high-ash fuels, because there are no other reserves in the processed raw material for the reasons explained above.

The current arrangement of production lines solves this problem by first gasifying or burning low-value fuels with a high ash content with a substoichiometric amount of air in a special unit, e.g. in a two-stage fluidized bed furnace, while the resulting combustible gas is introduced and burned directly at the point of heat demand, while the ash that is created in the gasification or combustion process is divided into a part that is mixed with the processed raw material and a part that is removed completely outside the technological process. This solution eliminates the problems caused by the difficult or complicated burning of low-value fuels with a high ash content directly in the burning line system while maintaining the quality of clinker with an optimal value of ash content, but it does not have the comprehensive character of a waste-free technology, because part of the ash removed outside the technological process creates landfills of unnecessary material with all the economic and ecological consequences.

The essence of the method of processing cement raw materials, in which solid inferior or waste fuel with a high ash content is first gasified or burned and the resulting flammable gas is burned immediately at the point of heat demand according to the invention, is that the resulting ash or solid waste is removed completely or partially outside the technological process of clinker firing and is further used as one of the correction components for the preparation of the raw material processed in this line, while this correction component subsequently participates in the entire process of chemical-technological treatment and preparation of the raw material.

The main advantage of the method of processing cement raw materials according to the invention is that it can completely replace any of the correction components used so far, which must be mined and transported to the place of final processing of the raw material. Furthermore, the ash can have

241 602 has a positive effect on the burnability of the raw material, because many oxides are bound in it in a significantly more reactive form than in some commonly used correction components, e.g. quartz sand.

The method according to the invention is described and explained below on the basis of a kiln line for firing cement clinker in a dry manner of a classical configuration, which consists of a rotary kiln, a clinker cooler and a raw material preheater. Another possible application is in a kiln line with partial or complete precalcination, which has an additional furnace or calciner built into the system.

These furnace lines include a fluidized bed furnace for gasification of low-value and high-ash solid fuels.

The solid fuel to be processed is fed into the fluidized bed, which creates a fluidized bed. A substoichiometric amount of air is fed into this fluidized bed, so that the fuel is incompletely burned and a combustible gas with a temperature of 900qřl000°C is produced. This combustible gas is fed to the place of heat demand, i.e. to a rotary kiln, to a calciner or to another suitable place. The combustion of this combustible gas does not cause any problems, its combustion temperature is sufficiently high, so that the thermal process is not negatively affected and the temperature of the waste gases from the system does not increase.

The ash and other solid waste that is generated during fuel processing in a fluidized bed furnace is removed from the lower part of the furnace in a known manner, while a part is introduced in a hot state into a rotary kiln or another part of the kiln line, where it mixes with the processed raw material and participates in the clinker firing process. However, this part is limited to such a proportion that it does not cause a disruption in the chemistry of the raw material or a subsequent reduction in the quality of the produced clinker, or does not cause problems with the formation of labels. The remaining, most of the ash is then cooled and removed outside the technological firing process and introduced into the line for the technological preparation of the raw material mixture, because the ash generated during the combustion of inferior fuels, as already mentioned, consists mostly of oxides that can be used for the composition of cement raw material. Ash is therefore used as one of the components of the raw material mixture. It passes through the entire raw material preparation line, including grinding and homogenization, which allows the preparation of a high-quality raw material mixture.

The cement clinker obtained by the method according to the invention will have all the quality parameters of the clinker produced using

241 602 noble fuel The operation of the entire line will be more technologically and operationally even, since there will be no fluctuations in the ash content in the raw material, and this will also facilitate automatic control of the preparation of the raw material and the firing of the clinker. The method thus allows the use of a significant amount of inferior, high-ash and waste fuels, the use of which is significantly limited by the use of existing methods of processing cement raw materials.

The possibility of replacing some of the correction components in the composition of cement raw materials by using all the ash generated in the combustion or gasification process is explained by an example. The example is solved for a coal briquette with the following parameters:

Calorific value Qj MJ . -1 Kg ¹ 15.69 Ash-original A % 45.17 SiO ₂ content in ash % 55.77 Content ⁱⁿ P°P ^el % 8.46 A^O^ content in ash % 24.67 , CaO content in ash % 1.66 The raw material is composed of • the following components i limestone stupid sand shale CaO content % ' 54.61 7.38 3.44 23.14 SiO content ₂ % 0.84 8.79 68.64 36.82 AlgO-j content % 0.48 8.30 13.45 11.02 Content % 0.21 2.56 0.42 8.46 Provided that that from total amount of heat needed for clinker firing is 40% supplied with high ash content and all- the resulting ash is used for transportation of raw materials, Gyly tents- the following ratios processed ingredients with Solution number 1 2 3 4 Degree of lime saturation To 94 94 94 100 Silicate module World Cup 2.3 2.3 1.85 1.8 Aluminate module MA 1.8 2.5 1.80 1.8 Limestone % 77.04 71.85 67.02 67.90 Kyzy % 1.75 1.27 2.71 2.66 Sand % 14.18 7.44 1.50 0.23 Slabs % 1.39 13.79 23.12 23.58 Ash % 5.66 5.60 5.66 5.66

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Alternatively, it is also possible to compose a raw material in which some components can be completely replaced with ash - see the following solution with

Solution number 5 6 Degree of lime saturation To 95 94 Silicate module 1β 2.3 1,785 Aluminate module MA 1.75 1.75 Limestone % 77.81 65.83 Kyay % 1.77 2.94 Sand % 14.76 Slabs % «· 25.58 Ash % 5,6.6 5.66

From the point of view of raw material preparation, the clinker firing process can therefore be optimized so that the most economically favorable components are used, or a correction component can be completely omitted.

The use of ash provides the opportunity to prepare raw materials for normally combustible cement.

Claims (1)

SUBJECT OF THE INVENTION 241 802 1. From pú.spb / production of cement clinker according to the basic MS. aut.osvědčení č.240675 P ^s which uses less solid waste throw the abundance or fuel with a high ash content, which is first gasified and the resulting combustible gas. immediately incinerated at the place of heat demand, the resulting ash or solid waste being discharged outside the technological process of "clinker burning", characterized in that the ash or solid waste is introduced at the beginning of the raw material preparation process and used as one of the raw material correction components mixtures processed in this line, taking part in the whole process of chemical-technological preparation and treatment of the raw material. Printed by Moravian Printing Works,