DE102017202325A1 - Process and device for the treatment of ash - Google Patents

Abstract

The present invention relates to a process for the treatment of ash (24), in particular fly ash, for use as a cement or building material additive, with ashes (24) having a glass content of less than 80%, preferably less than 70%, most preferably less than 60% %, is thermally treated so that the glass content is increased, the thermal treatment takes place at least partially with the waste heat thermal aggregate of heavy industry, such as the iron and steel industry, the basic industries, the cement industry and / or the lime or mineral industry Furthermore, the invention relates to a plant for the treatment of ash, in particular fly ash, for use as a cement additive, wherein the plant comprises means (22) for the thermal treatment of ash (24), in particular fly ash, having a glass content of less than 80%, preferably less than 70%, most preferably less than 60% is that it increases the glass content of the ash (24), wherein the means (22) for the thermal treatment of ash (24) so with a thermal aggregate of heavy industry, such as the iron and steel industry, the basic industries, the cement industry and / or the lime or mineral industry is in communication that their waste heat of the device (22) is supplied.

Description

The invention relates to a method and a device for the treatment of ash, in particular fly ash.

Cement production usually produces large amounts of CO2, which are mainly produced when processing raw meal into clinker. In order to reduce the CO2 emissions of cement plants, it has been known for some years to reduce the clinker factor and replace part of the clinker with latent hydraulic substances such as granulated blastfurnace, pozzolanic substances such as fly ash, burnt oil shale or natural pozzolans or limestone. As cement production increases worldwide, demand for clinker substitutes will continue to rise in the future.

In order to improve the properties of the cement as a clinker substitute, the pozzolanic reactivity of the clinker substitute is crucial, which depends essentially on the glass content. Fly ash, for example, is generated when burning coal in power plants. The pulverized coal is blown into the combustion chamber of the power plant and the ash is removed from the furnace as glassy solidified molten rock.

The current efforts of the power plant operators to achieve a better efficiency of the power plant and thus also to reduce the temperatures in the furnace, resulting in that the glass content of the ash is reduced and therefore no longer suitable for use as a cement clinker substitute in cement production. The processing of fly ash for use in the cement industry is known from numerous publications in relevant journals. Here, the fly ash is preferably chemically activated, so that the concentration of alkali metal or alkali metal silicate solutions is increased. However, this type of treatment of the fly ash is very expensive and expensive. A method for activating fly ash is also for example from the DE 11 2013 004 933 T5 known.

The object of the present invention is therefore to provide a simple and cost-effective method and a plant for the treatment of fly ash, the fly ash after treatment being suitable for use in the cement industry.

This object is achieved by a method having the features of the independent method claim 1 and a system having the features of the independent apparatus claim 8. Advantageous developments emerge from the dependent claims.

A method of treating ash, especially fly ash, for use as a cement additive or building additive in a first aspect comprises at least the steps of thermally rendering ashes having a glass content of less than about 80%, preferably less than 70%, most preferably less than 60% is treated so that the glass content of the ashes is increased, wherein the thermal treatment at least partially with the waste heat of a thermal aggregate of heavy industry, such as the iron and steel industry, the basic industries, the cement industry and / or the lime or mineral industry and / or takes place by at least one heat generator.

The ash, for example, is fly ash that is produced when burning coal in a coal-fired power plant. Fly ash is to be understood as meaning a fine-grained aluminosilicate or quartz-containing substance which has a particle size of about 1 μm to 1 mm and in particular can be transported by means of a gas stream. When burning coal in a power plant, the fly ash is discharged with the flue gas from the power plant and separated, for example in an electric filter from the flue gas. The fly ash prior to the thermal treatment, in particular a glass content of at least 20-80%, preferably 30-70%, most preferably 40-60%.

Under the waste heat of a thermal aggregate of heavy industry, such as the iron and steel industry, the basic industries, the cement industry and / or the lime or mineral industry is the, the thermal aggregate, such as a blast furnace, a rotary kiln or other combustion systems, leaving exhaust air or to understand a heat flow diverted from these aggregates. This is used, for example, directly or via heat exchangers for the thermal treatment of fly ash. The heat generator is, for example, a firing device, such as a furnace, in which the fly ash is thermally treated.

The thermal aggregate of the heavy industry is in particular a blast furnace for steelmaking, an oven or a combustion chamber, a calciner, a preheater and / or a cooler for cement production, or thermal treatment plants of the lime and / or mineral industry or thermal recycling plants ,

Thermal recovery systems are plants that are used for the purpose of recycling combustible waste or for the purpose of thermal treatment of waste with little or no calorific value.

The glass content of the ash includes the amorphous, glassy structure of the ash and is a measure of the pozzolanic reactivity of the ash. A pozzolanic reaction is understood to mean the chemical reaction of calcium hydroxide and silicon dioxide to calcium silicate hydrates, which in particular causes post-curing of concrete over a period of several years. The higher the glass content of the fly ash, the higher the pozzolanic reactivity of the ash. With a glass content of less than about 60%, the ash is at least partially unsuitable for use in the cement or building materials industry as a clinker additive.

By means of the thermal treatment of the ash, the glass content of the ash is increased, in particular in such a way that the ash is suitable for use in the cement industry. The thermal treatment is preferably carried out in a device for the thermal treatment of ash, the waste heat of a blast furnace for the production of pig iron, at least one unit from the steelmaking industry or a furnace, a calciner, a preheater and / or a cooler for cement production, or with the Waste heat of thermal treatment plants of lime and / or building materials and / or mineral industries or thermal treatment plants is fed. The thermal treatment is preferably carried out in a separate to the blast furnace, the calciner, the preheater, the rotary kiln and the cooler for cement production, or the thermal treatment plant of the lime and / or building materials and / or mineral industry or the thermal treatment plant.

A thermal treatment of the ash with at least partial use of the waste heat of a blast furnace to produce pig iron, at least one aggregate from the steelmaking industry or a furnace, a calciner, a preheater and / or a cooler for cement production, or the waste heat of thermal treatment plants of lime and / or building material and / or mineral industry or thermal recycling plants offers the advantage of efficient use of waste heat, whereby the specific ash is processed with a low glass content, so that it is suitable for use in the cement or building materials industry.

According to a first embodiment, the thermal treatment comprises heating the ash to a temperature above the melting temperature of the ashes of 850 ° C - 1800 ° C, especially 900 ° C - 1450 ° C, preferably 1000 ° C - 1150 ° C. The ash is heated according to a further embodiment at least partially by means of a firing device which is operated with biogenic substances and / or secondary fuels and / or fossil fuels and / or gas. The firing device heats the ash in addition to the waste heat from the blast furnace, furnace, calciner, preheater, radiator, or thermal treatment or recovery facilities. The heating of the ash to a temperature above the melting temperature of the ash allows the production of an amorphous, glassy structure, in particular by a rapid cooling of the ash following the heating.

The thermal treatment comprises, according to a further embodiment, the cooling of the ash after the heating, so that at least a portion of the ash solidifies glassy. Preferably, the ash is cooled to a temperature below about 350 ° C. The cooling takes place for example in a fluidized bed cooler or a standpipe cooler. A fluidized-bed cooler is a continuously charged, bubbling fluidized bed which has a heat exchanger by means of which the heat of the hot material can be removed. A riser cooler cools the material by dispersing the fine-grained hot material into a cold gas or air stream and subsequently separating it from the gas stream via a separator. The heated air in the cooling unit is preferably supplied to the upstream heat unit.

The ashes are milled according to a further embodiment following the thermal treatment. Preferably, the ashes, which are usually present in a lumpy fraction after the thermal treatment, are milled together with cement clinker. The milling is carried out in a milling device, such as a roller mill, a ball mill or a vertical roller mill. The grinder is followed in particular by the thermal treatment device, preferably the cooling unit of the ash and the clinker cooler of a cement plant.

The invention also includes a process for the production of cement, wherein raw material is heated in a preheater and at least partially deacidified in a calciner and wherein the raw material is burned in the cement to the calciner in an oven, in particular a rotary kiln to cement clinker and in a cooling the furnace subsequent cooler, wherein ash, in particular fly ash, according to a method as described above, processed and then supplied to the cement clinker. The thermal treatment of the ash is preferably carried out at least partially by the waste heat of the calciner, the furnace or the clinker cooler.

The glass content of the ash, according to another embodiment, is at least about 85% by the thermal treatment, preferably at least 90%, most preferably more than 95%, increased.

The invention further comprises a plant for the treatment of ash, in particular fly ash, for use as a cement or building material additive, the plant comprising a device for the thermal treatment of ash, in particular fly ash, with a glass content of less than 80%, preferably less than 70 %, most preferably less than 60%, which is designed to increase the glass content of the ashes, the ashes thermal treatment device having such a thermal aggregate of heavy industry, such as the iron and steel industry, the primary industry, the cement industry and / or the lime or mineral industry and / or with at least one heat generator in connection that their waste heat is supplied to the device. The thermal aggregate is, for example, a blast furnace for producing pig iron or at least one aggregate from the steelmaking industry or a preheater, an oven, a calciner and / or a cooler for cement production or a thermal treatment plant of lime and / or Building materials and / or mineral industry or a thermal recycling plant. The means for thermal treatment of the ash is preferably a separate device to the blast furnace, preheater, furnace, calciner, cooler or the thermal treatment or utilization plant.

The advantages and explanations given with regard to the process for the treatment of ash also apply in the apparatus-like equivalent to the plant for the treatment of ash.

According to one embodiment, the apparatus for thermal treatment of ash is designed such that it increases the glass content of the ash to at least about 85%, preferably at least 90%, most preferably more than 95%. Ash with such a glass content is suitable for use in the cement industry as an additive and can therefore replace a proportion of the cement clinker.

The device for thermal treatment, according to another embodiment, a heat aggregate, which is designed such that it is the ash to a temperature of 850 ° C - 1800 ° C, in particular 900 ° C - 1450 ° C, preferably 1000 ° C - 1150 ° C heated. The heat unit preferably has a firing device which is operable with biogenic substances and / or secondary fuels and / or fossil fuels and / or gas and heats the ash in addition to the waste heat. The firing device is arranged in particular within the heat aggregate.

According to a further embodiment, the heat aggregate has an aerodynamic aggregate, a fluidized bed aggregate or a fluidized bed reactor. In an aerodynamic generator, the ash is dispersed in a hot gas stream and separated from the gas stream via a fluid / solid separation system (e.g., cyclone), for example, in multiple stages. A fluidized bed reactor comprises a moving bed which is heated by a hot gas stream, with no dispersion in the gas stream. In a fluidized bed unit, the degree of dispersion is approximately between the degree of dispersion of the aerodynamic aggregate and the fluidized bed reactor.

According to a further embodiment, the device for thermal treatment on a cooling unit downstream of the cooling unit, which is designed such that it cools the heated ashes in the heat aggregate, so that at least a portion of the ash solidifies glassy. The refrigeration unit is, for example, a fluidized bed cooler or a standpipe cooler.

Following the device for thermal treatment, according to another embodiment, a grinder for grinding the thermally treated ash is arranged. The milling device, the thermally treated ashes, as well as, for example, the cooled in a clinker brick clinker supplied. Preferably, the ground clinker and the ground ash other additives, such as ground limestone, pozzolans, such as granulated slag, alkaline dusts and / or sulfate carriers such as gypsum, hemihydrate or anhydrite for improving the quality, in particular the pozzolanic reactivity of the cement and its Abbindeeigenschaften supplied ,

The invention also includes a plant for producing cement, comprising a preheater for preheating a raw material, wherein the preheater comprises in particular a calciner, and a furnace, in particular a rotary kiln, for firing the raw material into cement clinker and a cooling device for cooling the out of the furnace The plant comprises a plant for the treatment of ash, in particular fly ash, for use as a cement or building material additive as described above.

list of figures

• 1 zeigt eine schematische Darstellung einer Anlage zur Aufbereitung von Asche gemäß einem Ausführungsbeispiel.
• 2 zeigt eine schematische Darstellung einer Zementanlage mit einer Anlage zur Aufbereitung von Asche gemäß einem weiteren Ausführungsbeispiel.
• 3 zeigt eine schematische Darstellung einer Zementanlage mit einer Anlage zur Aufbereitung von Asche gemäß einem weiteren Ausführungsbeispiel.
• 4 zeigt eine schematische Darstellung einer Anlage zur Aufbereitung von Asche gemäß einem weiteren Ausführungsbeispiel.

The invention is explained in more detail below with reference to several embodiments with reference to the accompanying figures.

• 1 shows a schematic representation of an apparatus for the treatment of ash according to an embodiment.
• 2 shows a schematic representation of a cement plant with a plant for the treatment of ash according to another embodiment.
• 3 shows a schematic representation of a cement plant with a plant for the treatment of ash according to another embodiment.
• 4 shows a schematic representation of a plant for the treatment of ash according to another embodiment.

In 1 is a plant 10 for the treatment of ash. The attachment 10 includes a device 22 for thermal treatment of the ash 24 with a heat generator 26 for heating the ashes 24 and a refrigeration unit 28 to cool the ashes 24 , The heat aggregate 26 has an inlet 30 for the admission of ashes 24 on, as well as another inlet 34 for the admission of waste heat 32 in the heating unit 26 , The waste heat 32 For example, is a branched heat flow from a thermal aggregate of heavy industry, such as the iron and steel industry, the basic industries, the cement industry and / or the lime or mineral industry. For example, the heat flow from a blast furnace for pig iron production, or at least one unit from the steelmaking industry or an oven, a calciner, a preheater and / or a cooler for cement production, or a thermal treatment plant of the lime and / or mineral industry or a thermal recovery plant branched off , The heat aggregate 26 further comprises a firing device 36 on. The firing device 36 serves in addition to the waste heat 32 the heating of the ashes 24 , wherein the firing device 36 can be operated by means of biogenic substances and / or secondary fuels and / or fossil fuels and / or gas.

The heat aggregate 26 is preferably designed such that it is the ash 24 heated to a temperature above the melting temperature of the ash. In particular, the ashes 24 in the heat unit 26 heated to a temperature of 850 ° C - 1800 ° C, in particular 900 ° C - 1450 ° C, preferably 1000 ° C - 1150 ° C.

In the flow direction of the ash closes to the heat aggregate 26 the refrigeration unit 28 at. The refrigeration unit 28 has an inlet 38 for those in the heat aggregate 26 heated ash and includes, for example, a fluidized bed cooler or riser cooler, the ash 24 is cooled to a temperature of less than 350 ° C.

The heated ash 24 is in the refrigeration unit 28 cooled so that it has an amorphous, glassy structure with a glass content of about 85%, preferably at least 90%, most preferably more than 95%. By way of example, the thermal treatment device comprises 22 a in 1 Not shown drying unit in which the fly ash following the cooling unit 28 is dried.

The attachment 10 further comprises a grinder, such as a roller mill, a ball mill, a stirred ball mill or a vertical roller mill. The grinder is downstream of the thermal processor 22 arranged. The from the institution 22 ash for thermal treatment is fed to the grinding device 20 and ground in this. The grinder 20 will be in addition to that in the facility 22 recycled ash cement clinker 40 fed. For example, the grinder is 20 one in 1 downstream not shown clinker cooler. The together with the clinker 40 ground ash leaves as finished product 42 the grinder 20.

2 shows a plant 44 for the production of cement with a preheater 12 which has a plurality of cyclones. Exemplary are in 1 represented four cyclone stages, which are traversed by the raw material. In the preheater 12 In particular, the material is preheated and in the calciner 14 acidified. To the preheater 12 closes in the flow direction of the material an oven 16 , in particular a rotary kiln 16 in which the material is fired into cement clinker. At the furnace outlet, the material, in particular the fired cement clinker, a temperature of about 1400 - 1600 ° C, preferably 1500 ° C, on. The in the oven 16 resulting hot gases first flow through the calciner 14 and then the preheater 12 in countercurrent to the material flow direction, so that heating of the material takes place. In the precalcination (deacidification), the hot raw meal emerging from the second lowest cyclone stage is removed from the oven 16 entrained hot gas entrained and into the calciner 14 led, between the preheater 12 and the oven 16 is arranged. This is usually a riser in which furnace gas and kiln are fed in DC and react with each other. To the endothermic expiring To maintain deacidification, the calciner indicates 14 in addition to the hot furnace gases, a furnace which is operable by means of biogenic substances and / or secondary fuels and / or fossil fuels and / or gas.

To the stove 16 closes in the flow direction of the material a cooler 18 for cooling the out of the oven 16 on leaked material. At the radiator 18 For example, it is a sliding grate cooler or an underflow cooler in which the material lying on the sliding grate or the sliding floor is cooled in crossflow by a cooling air flow. The cooler 18 For example, the material cools to a temperature of about 80 ° C to 150 ° C.

The attachment 44 for the production of cement also has an attachment 10 for the treatment of ash 24 on, which is essentially the in 1 described plant 10 equivalent. The attachment 10 includes a device 22 for thermal treatment of the ash 24 with an in 2 not shown heat unit and a cooling unit. Following the setup 22 for thermal treatment of the ash 24 and after the cooler 18 is a grinder 20 arranged in which a crushing of the cooled material takes place. At the grinder 20 For example, it may be a roller mill, a ball mill, a stirred ball mill or a vertical roller mill.

The device 22 for thermal treatment of the ash 24 is in the embodiment of 2 the waste heat of the calciner 14 fed. In particular, of the in the riser of the calciner 14 guided hot air flow diverted at least a portion and the device 22 fed. The device 22 for thermal treatment of the ash 24 is with the calciner 14 and the grinder 20 connected to the device 22 ash introduced for thermal treatment 24 as related to 1 described thermally treated and then together with, for example, in the oven 16 baked cement clinker is ground. A separate grinding of the clinker and the thermally treated ash is conceivable.

In 3 is another embodiment of a cement plant 44 which is essentially the one with reference to 2 described cement plant 44 Corresponds with the difference that the device 22 for thermal treatment of ash 24 the plant 10 with the oven 18 communicates. The device 22 for thermal treatment of ash 24 the waste heat of the furnace, in particular at least part of the gas stream heated in the furnace, is supplied. The device 22 for thermal treatment of the ash 24 is with the oven 16 and the grinder 20 connected to the device 22 ash introduced for thermal treatment 24 as related to 1 described thermally treated and then together with the in the oven 16 baked cement clinker is ground.

4 shows a further embodiment of a plant for the preparation of fly ash, which, in contrast to the embodiments of the 2 and 3 in place of the waste heat of a cement plant, the waste heat of a thermal plant 50 , Such as a blast furnace, a thermal mineral treatment plant or a plant for thermal waste utilization of the thermal treatment device 22 is supplied. In particular, this waste heat is the heat aggregate 26 the thermal processing device 22 supplied and, for example, in addition to the firing device 36 used for heating the fly ash. It would also be conceivable that the ashes before heating in the heat aggregate 26 is dried by at least partial use of waste heat, such as radiator exhaust air of a clinker cooler. The resulting exhaust stream could be at least partially used for energy production, such as power generation.

LIST OF REFERENCE NUMBERS

10

Plant for the treatment of ash

12

preheater

14

calciner

16

oven

18

cooler

20

grinder

22

Device for thermal treatment

24

ash

26

heat unit

28

cooling unit

30

Inlet for the admission of ashes

32

waste heat

34

Inlet for the admission of waste heat

36

firing

38

Inlet for the admission of ashes

40

cement clinker

42

finished product

44

Plant for the production of cement

50

Thermal engineering plant

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 112013004933 T5 [0004]

Claims (14)

Process for the treatment of ash (24), in particular fly ash, for use as a cement or building material additive, characterized in that ash (24) having a glass content of less than 80%, preferably less than 70%, most preferably less than 60%, is thermally treated so that the glass content is increased, wherein the thermal treatment takes place at least partially with the waste heat of a thermal aggregate of heavy industry, such as the iron and steel industry, the basic industries, the cement industry and / or the lime or mineral industry. Method according to Claim 1 wherein the thermal treatment comprises heating the ash (24) to a temperature above the melting temperature of the ash (24) of 850 ° C - 1800 ° C, especially 900 ° C - 1450 ° C, preferably 1000 ° C - 1150 ° C , Method according to Claim 2 wherein the thermal treatment comprises cooling the ash (24) following heating so that at least a portion of the ash (24) is glassy solidified. Method according to Claim 2 or 3 in that the ash is at least partially heated by means of a firing device (36) which is operated with biogenic substances and / or secondary fuels and / or fossil fuels and / or gas. Method according to one of the preceding claims, wherein at least a portion of the ash (24) is ground following the thermal treatment. A method of producing cement, wherein raw material is heated in a preheater (12) and at least partially deacidified in a calciner (14), and wherein the raw material following the calciner (14) in an oven (16), in particular a rotary kiln to cement clinker is burned and cooled in a subsequent to the furnace (16) radiator (18), characterized in that ash (24), in particular fly ash, by a method according to one of Claims 1 to 5 treated and then supplied to the cement clinker. A method according to any one of the preceding claims, wherein the glass content of the ash (24) is increased by the thermal treatment to at least about 85%, preferably at least 90%, most preferably more than 95%. Plant for the treatment of ash, in particular fly ash, for use as a cement additive, characterized in that the plant comprises means (22) for thermal treatment of ash (24), in particular fly ash, having a glass content of less than 80%, preferably less than 70 %, most preferably less than 60%, which is adapted to increase the glass content of the ash (24), wherein the means (22) for thermal treatment of ash (24) is such with a thermal aggregate of heavy industry, such as the iron and steel industry, the basic industry, the cement industry and / or the lime or mineral industry is in communication that their waste heat is supplied to the device (22). Plant after Claim 8 wherein the means (22) for thermal treatment of ash (24) is adapted to increase the glass content of the ash (24) to at least about 85%, preferably at least 90%, most preferably more than 95%. Plant according to one of the Claims 8 to 10 wherein the means (22) for thermal treatment comprises a heat generator (26) adapted to hold the ash (24) at a temperature of 850 ° C - 1800 ° C, especially 900 ° C - 1450 ° C, preferably 1000 ° C-1150 ° C, heated. Plant after Claim 10 wherein the heat generator (26) comprises an airflow aggregate, a fluidized bed unit or a fluidized bed reactor. Plant after Claim 11 wherein the means (22) for thermal treatment comprises a cooling unit (28) connected downstream of the heating unit (26), which is designed to cool the ash (24) heated in the heating unit (26) so that at least part of the ash (24) glassy solidified. Plant according to one of the Claims 8 - 12 , wherein after the means (22) for the thermal treatment, a grinder (20) for grinding the thermally treated ash (24) and / or the cement clinker is arranged. Plant (44) for producing cement, comprising a preheater (12) for preheating a raw material, and an oven or combustion chamber (16), in particular a rotary kiln, for firing the raw material into cement clinker and a cooling device (18) for cooling the The cement clinker leaving the furnace (16), characterized in that the plant (44) has a plant (10) for the treatment of ash, in particular fly ash, for use as Cement additive according to one of Claims 8 to 13 includes.

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