JP5172728B2 - Cement manufacturing method and manufacturing apparatus - Google Patents

Description

  The present invention relates to a cement manufacturing method and a manufacturing apparatus, and in particular, from dust contained in gas extracted from a kiln exhaust gas passage from a kiln bottom of a cement kiln to a lowermost cyclone, lead, etc. The present invention relates to a method and apparatus for separating heavy metals.

  Conventionally, since lead (Pb) in cement is immobilized, it has been considered that there is no elution into soil. However, as the amount of recycled resources used in cement production has increased in recent years, the amount of lead in cement has also increased, and its content has been greatly exceeded. Since there is a possibility that the risk of leaching into the soil increases with increasing concentration, a technique for reducing the lead concentration in the cement to the conventional content level is necessary.

  In recent years, the recycling of wastes into cement raw materials or fuels has been promoted, and as the amount of waste processed increases, the amount of volatile components such as chlorine, sulfur, and alkali brought into the cement kiln also increases. The amount of bypass dust is also increasing. Chlorine bypass dust is used in the cement crushing process, but it is expected that the generation amount will increase and the allowable cement concentration of heavy metals including lead will be exceeded. There was a need to develop a method for removing and recovering heavy metals from the cement manufacturing process.

  Therefore, for example, in Patent Document 1, in order to effectively separate and remove chlorine and lead in the waste supplied to the cement manufacturing process, the waste water washing step and the filtered solid alkali elution A step, a deleading step for precipitating and separating lead from the filtrate, a decalcifying step for precipitating and separating calcium from the deleaded filtrate, and heating the filtrate to precipitate chlorides for separation Disclosed is a waste processing method including a salinity recovery step.

  Further, in Patent Document 2, in separating and removing lead and zinc from waste such as fly ash, a solution containing calcium ions is mixed to obtain a slurry, followed by solid-liquid separation to obtain a solid containing zinc. And a step of obtaining an aqueous solution containing lead, a step of obtaining a solution containing lead sulfide and calcium ions by solid-liquid separation after adding a sulfurizing agent to the aqueous solution containing lead, etc. A processing method is described.

  Further, Patent Document 3 extracts a part of the cement kiln combustion gas from the cement manufacturing process, collects dust contained in the extracted combustion gas, and removes one or more selected from thallium, lead, and selenium. Alternatively, a method for removing and recovering heavy metals from a cement manufacturing process characterized by recovering is described.

Patent Document 4 discloses that the raw material temperature in the cement kiln is 800 to 1100 ° C. by controlling the O ₂ concentration of the combustion gas in the kiln bottom of the cement kiln to 5% or less and / or the CO concentration to 1000 ppm or more. Lead in which the area is reduced to promote volatilization of lead, and then a part of the combustion gas in the cement kiln is extracted to collect the dust contained in the combustion gas and to recover the lead from the collected dust A removal method is described.

JP 2003-1218 A JP 2003-201524 A JP 2006-347794 A International Publication 2008/050678 Pamphlet

  However, in the methods described in Patent Documents 1 to 3, heavy metals such as lead contained in the chlorine bypass dust are removed, but the ratio of heavy metals removed out of the system through the chlorine bypass dust is: Only about 30% of the total, even if 100% of the heavy metals in the chlorine bypass dust are removed, the remaining 70% is still taken up by the clinker manufactured in the cement kiln. It is not easy to reduce the content. Therefore, it is important to promote the volatilization of heavy metals in the cement kiln and increase the concentration rate of heavy metals in chlorine bypass dust.

  Here, a chlorination volatilization method and a reduction volatilization method are known as heavy metal volatilization techniques. However, if the chlorination volatilization method that is generally performed is applied to the cement firing step, it is necessary to input a much larger amount of chlorine than a common amount in cement production. On the other hand, the application of the reduction volatilization method is problematic in terms of cement quality because the color of the cement is yellow.

  Further, in the method described in Patent Document 4, in order to increase the volatilization rate of heavy metals, the oxygen concentration in the kiln bottom of the cement kiln is suppressed, and an atmosphere that generates CO gas is formed. There is a problem that there is a risk of explosion of an electric dust collector for collecting dust contained in cement kiln combustion gas and generation of harmful substances such as dioxins.

  Therefore, the present invention has been made in view of the problems in the conventional technology described above, and does not affect the quality of the cement, ensures the safety of the cement manufacturing apparatus, and does not increase the environmental load. The purpose is to efficiently separate heavy metals from the cement manufacturing process.

  In order to achieve the above object, the present invention is a cement manufacturing method, comprising mixing a substance containing fixed carbon and a substance containing chlorine, and granulating the granulated product, with the intermediate of the kiln in the cement kiln. From the kiln exhaust gas flow path from the kiln bottom of the cement kiln to the lowermost cyclone, and extracting a part of the combustion gas from the kiln bottom of the cement kiln to the lowermost cyclone. , Collecting dust contained in the combustion gas, and separating heavy metals from the collected dust.

  And according to the present invention, from the middle of the kiln of the cement kiln, the mixed granulated product of the substance containing fixed carbon and the substance containing chlorine content from the lowermost cyclone section of the preheater attached to the cement kiln Thus, the volatilization rate of heavy metals in the kiln can be increased, and the concentration rate of heavy metals at the position where a part of the combustion gas of the cement kiln is extracted can be increased. Therefore, when a part of the combustion gas of the cement kiln is extracted, heavy metals extracted along with the combustion exhaust gas increase, so that heavy metals can be efficiently recovered with chlorine bypass dust or the like. Here, by using a granulated material in which a substance containing fixed carbon and a substance containing chlorine are used, a target position and a temperature range of 900 ° C. that can efficiently volatilize and concentrate heavy metals in a cement kiln and the like. Both fixed carbon and chlorine content can be supplied to ˜1300 ° C., and the volatilization rate of heavy metals can be maintained high, and the concentration rate of heavy metals at a position where a part of the combustion gas is extracted can be increased. Furthermore, the safety of the cement manufacturing apparatus can be ensured, and it can be carried out without increasing the environmental load.

  In the cement manufacturing method, the granulated product can be supplied to the section after adjusting the particle size to 5 mm or more and 50 mm or less. This makes it possible to promote heavy metal recovery / removal from the cement manufacturing process.

  In the cement manufacturing method, the substance containing fixed carbon may be coke, coal, anthracite, bituminous coal, lignite, graphite, charcoal, mixed coke, fine coke, activated coke, electrode scrap, waste toner, heavy oil ash and fly ash. A group consisting of fine powders of 0.1 μm to 1 mm each of unburned carbon contained in the powder, and fine powders of 0.1 μm to 1 mm of each of the carbides of flame retardant plastic, phenol resin, furan resin, thermosetting resin and cellulose It can be 1 or 2 or more selected.

Further, in the above cement manufacturing method, the substance containing chlorine is selected from alkali metal chlorides such as NaCl, KCl, and CaCl ₂ , alkaline earth metal chlorides, metal chlorides such as FeCl ₂ and CuCl ₂ , and chlorine-containing waste plastics. 1 or 2 or more selected from the group consisting of vinyl chloride, municipal waste incineration ash, dredged clay, and scrapped car shredder dust.

  The present invention also relates to a cement manufacturing apparatus comprising a granulating apparatus for mixing and granulating a substance containing fixed carbon and a substance containing chlorine, and a cement kiln attached to the cement kiln from the middle of the kiln. A supply device for supplying the granulated material granulated by the granulation device from the section of the preheater to the lowermost cyclone, and a kiln exhaust gas flow path from the kiln bottom of the cement kiln to the lowermost cyclone An extraction device for extracting a part of the combustion gas, a dust collector for collecting dust contained in the combustion gas extracted by the extraction device, and separating heavy metals from the dust collected by the dust collector And a heavy metal separation device. According to the present invention, similarly to the above-described invention, it is possible to ensure the safety of the cement manufacturing apparatus and efficiently recover heavy metals without increasing the environmental load.

  As described above, according to the present invention, heavy metals are efficiently separated from a cement manufacturing process without affecting the cement quality, ensuring the safety of the cement manufacturing apparatus, and increasing the environmental load. be able to.

It is the schematic which shows one Embodiment of the cement manufacturing apparatus concerning this invention. It is a flowchart which shows the whole structure of the chlorine bypass apparatus attached to a cement kiln. It is the schematic for demonstrating the Example of the cement manufacturing apparatus concerning this invention.

  Next, modes for carrying out the present invention will be described with reference to the drawings. In the following description, heavy oil ash is used as a substance containing fixed carbon, and automobile shredder dust (hereinafter referred to as “ASR”) is used as a substance containing chlorine to separate lead, which is one of heavy metals. Will be described as an example.

  FIG. 1 shows an embodiment of a cement production apparatus according to the present invention. This cement production apparatus 1 includes a kneading / mixing machine 2 for kneading / mixing heavy oil ash, ASR and water, and a kneaded / mixed raw material. A granulator 3 for granulating, a dryer 4 for drying the granulated product (hereinafter referred to as “pellet”) P, and a dried product (hereinafter referred to as “dry pellet”) D for cement kiln ( (Hereinafter abbreviated as “kiln”) 7 to the section (from the kiln bottom 7a in this embodiment) from the middle of the kiln 7 to the lowest cyclone 8 of the preheater attached to the kiln 7 Etc.

  The kneading / mixing machine 2 is provided to add water to heavy oil ash to obtain viscosity necessary for granulation and to mix heavy oil ash and ASR. For example, a kneader / mixer 2 A batch type or continuous type kneading / mixing machine such as a mixer or a pro-shear mixer can be used. In addition, when using a batch type kneading / mixing machine, an apparatus for keeping the supply to the granulator 3 constant is provided.

  The granulator 3 is provided for granulating the kneaded / mixture M from the kneading / mixing machine 2 into pellets P. For example, an extruding type (disc pelleter, press pelleter, etc.), a compression type (tablet machine, Briquette machine etc.) and rolling type (pan pelletizer etc.) can be used.

  The dryer 4 is provided in order to dry the pellets P and improve the handling properties, and can dry the pellets P using the kiln 7 or preheater exhaust gas, clinker cooler exhaust gas, chlorine bypass exhaust gas, or the like. . If the strength of the pellet P is sufficient, the dryer 4 can be omitted.

  The feeding device 5 uses a device capable of quantitative feeding such as a belt feeder, an apron feeder, and a vibration feeder, and the kiln 7 may drop the dried pellet D naturally from the chute 6 and use air or the like. Then, it may be ejected from the kiln butt 7 a to the inside of the kiln 7, and can be introduced from the body part of the kiln 7. Moreover, if the granulation amount in the granulator 3 can be fixed, the pellet P can also be directly injected into the kiln 7 from the granulator 3.

  On the other hand, as shown in FIG. 2, the kiln 7 is provided with a chlorine bypass device 20, and the extracted gas G1 from the kiln exhaust gas flow path from the kiln bottom 7a of the kiln 7 to the lowermost cyclone 8 (see FIG. 1). After being cooled by the cooling air A from the cooling fan 23 in the probe 22, it is introduced into the classifier 24 and separated into coarse dust D1, fine powder D2, and gas G2. Coarse dust D1 is returned to kiln 7, fine powder D2 and gas G2 are cooled by cooler 25, and fine powder (chlorine bypass dust) D2 containing potassium chloride (KCl) or the like is collected by dust collector 27. The exhaust gas G3 discharged from the dust collector 27 is returned to an exhaust gas flow path such as a preheater attached to the kiln 7 or an outlet of the preheater via an exhaust fan 29.

  Next, the cement manufacturing method according to the present invention using the cement manufacturing apparatus 1 will be described.

  As shown in FIG. 1, ASR and heavy oil ash are introduced into the kneading / mixing machine 2 using a quantitative feeder so as to have a predetermined chlorine concentration, and water is added so as to have a predetermined water content. Kneading / mixing. At that time, in order to ensure the strength of the pellet P, it is better to use ASR which has been subjected to pretreatment such as sieving, removal of foreign matters by a magnetic separator, or particle size adjustment by crushing.

  The amount of water added in the kneading / mixing machine 2 is preferably added so that the water content is 15% by mass or more and 50% by mass or less with respect to the dry base heavy oil ash before granulation. If the mass of water to be added is less than 15% by mass, heavy oil ash cannot be pelletized, and there is a problem that a product with a desired particle size cannot be obtained. There is a problem that granulation cannot be performed due to an increase in adhesiveness during kneading / mixing, and pellets adhere to each other after granulation. In addition, when desired intensity | strength cannot be obtained, it is also possible to add additives, such as bentonite, lignin, water glass, polyvinyl alcohol, suitably.

  Next, the kneaded / mixed heavy oil ash and ASR are granulated by the granulator 3 to obtain pellets P with adjusted water content. The pellet P is made into pellet P by the granulator 3 when the particle size is too small when it is introduced from the kiln bottom 7a or the like, accompanied by the gas flowing through the kiln exhaust gas flow path, and the heavy oil ash on the lowermost cyclone 8 side. This is because the ASR flows, and as a result, the heavy oil ash to the lead volatilization region and the ASR supply amount to the lead concentration region are reduced, and it is avoided that efficient lead volatilization / recovery cannot be performed.

  In the granulator 3, it is preferable that the pellet P is granulated so that the particle diameter is 5 to 50 mm, and then the dried pellet 4 is formed by the dryer 4. When the particle size of the dry pellet D is less than 5 mm, the dry pellet D thrown into the kiln 7 scatters, the supply amount of the dry pellet D to the lead volatilization temperature range decreases, and an efficient volatilization rate is ensured. It becomes impossible to concentrate and recover lead efficiently. On the other hand, when the particle size of the dry pellet D exceeds 50 mm, there is a concern that the color of the cement exhibits a yellow color, causing a problem in terms of cement quality.

  Next, during the cement firing by the kiln 7, the dry pellet D is introduced from the kiln bottom 7 a of the kiln 7 by the input device 5, and volatilization of lead in the kiln 7 is promoted.

  The lead volatilized in the kiln 7 is contained in the gas extracted by the probe 22 in FIG. 2, and the extracted gas G1 is cooled in the probe 22 and then introduced into the classifier 24, and the coarse dust D1 and fine powder. It is separated into D2 and gas G2, and finally the fine powder D2 is collected by the dust collector 27. The fine powder D2 is produced by the kiln 7 because the lead is volatilized more and the lead is concentrated more than before, so that the lead is efficiently removed by separating the lead. The lead content of cement clinker can be reduced.

  In the above embodiment, lead is separated from chlorine bypass dust. However, zinc, cadmium, antimony, selenium, arsenic, and thallium can be separated in the same manner as described above.

  In addition to chlorine bypass dust, a part of the combustion gas is extracted from the kiln exhaust gas passage from the kiln bottom 7a of the kiln 7 to the lowermost cyclone 8, and if it is dust contained in the extracted combustion gas, The heavy metals can be separated by the same method as described above.

  In the above embodiment, heavy oil ash is exemplified as a substance containing fixed carbon, but coal, anthracite, bituminous coal, brown coal, graphite, charcoal, coke, mixed coke, fine coke, activated coke, electrode scrap, waste toner , 0.1 μm or more and 1 mm or less of each of unburned carbon contained in heavy oil ash and fly ash, and 0.1 μm or more and 1 mm of each of carbides of flame retardant plastic, phenol resin, furan resin, thermosetting resin and cellulose, respectively. The following fine powders can be used.

ASR is exemplified as the substance containing chlorine, but alkali salts such as NaCl, KCl and CaCl ₂ , metal salts such as FeCl ₂ and CuCl ₂ , chlorine-containing waste plastics, vinyl chloride, municipal waste incineration ash, clay Waste car shredder dust or the like can also be used.

Next, an embodiment of the present invention will be described with reference to FIG. In this embodiment, the cement manufacturing apparatus 1 shown in Table 1 and the chlorine bypass apparatus 20 shown in FIG. 2 are used, heavy oil ash is used as the substance containing fixed carbon, and CaCl ₂ is used as the substance containing chlorine. Was used to separate lead, one of the heavy metals.

  In FIG. 3, a continuous kneader (manufactured by Dalton Co., Ltd.) is used for the kneading / mixing machine 2, a disk pelleter (manufactured by Dalton Co., Ltd.) dryer 4 is used for the granulator 3, and a box is used. A mold dryer (manufactured by our company, generating hot air with a jet heater and drying it) was used.

After 120 kg / h of heavy oil ash and CaCl ₂ were kneaded / mixed by the kneading / mixing machine 2 with the formulation shown in FIG. 1, 10 mmφ pellets P were produced by the granulator 3. The water content of the pellet P was adjusted to 30% by mass. Further, CaCl ₂ was added to the kneading / mixing machine 2 as an aqueous solution so as to have a predetermined moisture content and input amount. The pellet P after granulation was dried with a dryer 4 until the water content became 2% by mass or less.

  The dried pellet D dried by the dryer 4 is introduced from the kiln bottom 7a of the kiln 7, the lead volatilization rate ((1-clinker lead concentration / lead concentration in raw material of the lowermost cyclone 8) × 100), and chlorine bypass device The lead concentration of fine powder D2 at 20 was measured. The lead volatilization rate and lead concentration measurement results are shown in Table 1.

In the same table, the blank indicates a case where neither heavy oil ash nor CaCl _{2 is} added, and level 1 indicates a case where dry pellet D is produced using only heavy oil ash and is introduced from kiln bottom 7a. From the same table, heavy oil ash and CaCl ₂ are mixed and granulated, and then introduced from kiln bottom 7a, lead volatilization rate and lead concentration of fine powder D2 increase, especially compared to blanks etc. at level 4. It can be seen that these values are greatly increased and lead can be separated efficiently.

DESCRIPTION OF SYMBOLS 1 Cement manufacturing apparatus 2 Kneading / mixing machine 3 Granulator 4 Dryer 5 Input apparatus 6 Chute 7 Cement kiln 7a Kiln bottom 8 Bottom cyclone 20 Chlorine bypass apparatus 22 Probe 23 Cooling fan 24 Classifier 27 Dust collector 29 Exhaust fan

Claims (5)

Mix and granulate a substance containing fixed carbon and a substance containing chlorine,
Supplying the granulated material to the section from the middle of the kiln of the cement kiln to the lowermost cyclone of the preheater attached to the cement kiln;
Extracting a part of the combustion gas from the kiln exhaust gas flow path from the bottom of the kiln of the cement kiln to the lowermost cyclone,
Collecting dust contained in the combustion gas;
A method for producing cement, comprising separating heavy metals from the collected dust.   The cement production method according to claim 1, wherein the granulated product is supplied to the section after adjusting the particle size to 5 mm or more and 50 mm or less.   The substance containing the fixed carbon is each of unburned carbon contained in coke, coal, anthracite, bituminous coal, lignite, graphite, charcoal, mixed coke, fine coke, activated coke, electrode scrap, waste toner, heavy oil ash and fly ash. 1 or 2 or more selected from the group consisting of 0.1 to 1 mm fine powder and 0.1 to 1 mm fine powder of each flame-retardant plastic, phenol resin, furan resin, thermosetting resin and cellulose The method for producing a cement according to claim 1 or 2, wherein:   The substance containing chlorine is selected from the group consisting of alkali metal chlorides, alkaline earth metal chlorides, metal chlorides, chlorine-containing waste plastics, vinyl chloride, municipal waste incineration ash, dredged soil, and waste car shredder dust. The cement manufacturing method according to claim 1, 2 or 3, characterized in that the number is 1 or 2 or more. A granulator for mixing and granulating a substance containing fixed carbon and a substance containing chlorine; and
A supply device for supplying the granulated material granulated by the granulator from the middle of the kiln of the cement kiln to the lowermost cyclone of the preheater attached to the cement kiln;
An extraction device for extracting a part of the combustion gas from the kiln exhaust gas flow path from the bottom of the cement kiln to the lowermost cyclone;
A dust collector that collects dust contained in the combustion gas extracted by the extraction device;
A cement manufacturing apparatus, comprising: a heavy metal separation device that separates heavy metals from dust collected by the dust collection device.

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