JP2011067764A - Method and apparatus for recovering concrete sludge fine powder and concrete sludge fine powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recovering a concrete sludge fine powder, which gives, at a low cost, a high-quality concrete sludge fine powder containing a high content of cement in which a hydration reaction has not proceeded. <P>SOLUTION: Gravel and sand are separated from a slurry object to be treated such as residual concrete by predetermined sieves (3 and 5) so that a sand content becomes 10 mass% or less, and a fine sand component is then separated and removed by a wet cyclone to obtain concentrated sludge water. The concentrated sludge water is subjected to a filter press to obtain a dehydrated cake having a water content of 25-45 mass%. The dehydrated cake is continuously supplied from one end of a rotary drum (21) of a rotary dryer (RD) and is crushed by crushing-stirring blades (31) while being scooped by lifters (35) to a predetermined height and dropped. During this, hot air is blown into the rotary drum (21) from the one end thereof to substantially simultaneously perform crushing and drying. The concrete sludge fine powder is continuously obtained from the other end. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a treatment process for obtaining a dehydrated cake by treating a slurry-like workpiece such as residual concrete or return concrete to which predetermined water has been added, or washing waste water generated from a ready-mixed concrete factory, and the treatment process. The present invention relates to a concrete sludge fine powder recovery method and recovery apparatus, and a concrete sludge fine powder comprising a crushing / drying step of drying while crushing a dehydrated cake obtained by the above.

  Concrete made of cement, sand, gravel, mortar made of cement and sand, etc. are generally manufactured by a ready-mixed concrete factory provided at a predetermined location. And, it is transported from the ready mixed concrete factory to the concrete placement site by a concrete mixer truck. Such a ready-mixed concrete factory includes a mixer for mixing concrete as is well known in the art. A mixer truck can be placed under the concrete mixing mixer. After completion of the kneading, when the gate of the concrete mixing mixer is opened, the concrete is supplied to the delivered mixer truck by gravity through the hopper. In a similar manner, mortar is also manufactured and fed to the mixer truck via gravity via a hopper.

  Concrete, mortar, etc. manufactured as described above are transported to the concrete placement site by a mixer truck, and unloaded by rotating the drum in the reverse direction, but adheres to the chute, discharge blade, etc. of the mixer truck after unloading. The mortar or the like is washed before solidifying. By the way, the cleaning waste water generated after cleaning contains cement components, and thus becomes industrial waste. Therefore, it is not permissible to dispose directly in vacant land, roads, rivers, etc. near the unloading site. In general, there is no facility for treating cleaning wastewater at the concrete placement site. Therefore, the washing wastewater is collected on the drum of the mixer truck, transported to the ready mixed concrete factory, and discharged to the attached washing wastewater treatment facility for treatment. This is also true for the treatment of residual concrete and return concrete.

  The above-mentioned concrete kneading mixer, washing waste water obtained by washing a transporting mixer truck, etc., and treated waste water obtained by treating residual concrete, return concrete, etc. may be used as part of the concrete kneading water. Proposed. In addition to gravel and sand, washing wastewater and treated wastewater contain solid matter, that is, sludge. This sludge powder can be used as a silicate lime fertilizer and as an improvement material for soft ground. Thus, various methods and apparatuses for collecting concrete sludge fine powder have been proposed in the patent literature. In particular, Patent Document 1 can be cited as a direct prior art document of the present invention.

JP 2002-254099 A

Patent Document 1 describes a method for collecting concrete sludge fine powder comprising the following steps (A) to (G).
(A) a fine sand removal step for obtaining recovered water from which fine sand contained in washing wastewater and treated wastewater is removed so that the sand content is 10% by mass or less;
(B) a coagulation-precipitation step of adding an inorganic flocculant to the recovered water obtained by the step and separating and precipitating into supernatant water and sludge water;
(C) a dehydration treatment step of dewatering the sludge water separated in the step to produce a dehydrated cake;
(D) Crushing treatment step of crushing the dehydrated cake obtained in this step before curing, and plane rolling to a thickness of 10 to 15 mm;
(E) a drying step of drying the dehydrated cake crushed in the step so that the water content is 50 to 60% by mass and the maximum particle size is 20 mm or less;
(F) a fine pulverization step for producing rounded fine particles by finely pulverizing the dry sludge obtained in the step with a pulverizer using wind power;
(G) The concrete sludge fine powder collection | recovery method including the collection process which collects the microparticles | fine-particles manufactured at this process is described.

  Further, as an embodiment for carrying out the above-described recovery method, Patent Document 1 discloses a concrete sludge fine powder recovery device as shown in FIG. That is, an aggregate recovery device 51 that selectively sorts gravel, sand, etc. in cleaning wastewater / treatment wastewater, a wet cyclone 52 that separates fine sand in the cleaning wastewater / treatment wastewater removed by the aggregate recovery device 51, A coagulating sedimentation tank 53 for precipitating solids by adding an inorganic coagulant to the overflow of the wet cyclone 52, a dewatering apparatus 54 for concentrating sludge water separated in the coagulating sedimentation tank 53 to obtain a dehydrated cake, 54, a crusher 55 that crushes the dehydrated cake obtained by the crusher 54, a dryer 56 that dries the dehydrated cake crushed by the crusher 55, and a wind-powered crusher 57 that finely crushes the dried sludge dried by the drier 56. , A concrete sludge fine powder recovery device composed of a dry cyclone 58 or the like for recovering sludge finely pulverized by this wind power pulverizer 57 is shown. There.

  The invention described in Patent Document 1 treats cleaning wastewater generated from a ready-mixed concrete factory and treated wastewater obtained by treating residual concrete, and fine sand content is reduced so that the sand content is 10% by mass or less. Since it has the process or means to remove, it has the characteristic that the fine concrete sludge fine powder suitable for reuse can be obtained. However, various points to be improved are recognized.

  For example, Table 1 below is a table showing the chemical components of the sludge fine powder obtained by the apparatus described in Patent Document 1, but as shown in Table 1, it is compared with the loss on ignition of ordinary Portland cement. And the ignition loss of the sludge fine powder of patent document 1 is very large. In contrast, the amount of calcium oxide (CaO) is small. The reason why the amounts are different is considered to be because the hydration reaction of the cement is in progress. That is, calcium oxide in cement absorbs moisture and becomes calcium hydroxide, and further combines with carbon dioxide to become calcium carbonate. However, the amount of calcium oxide decreases as the hydration reaction proceeds, and conversely, And the carbon dioxide content, in other words, the loss on ignition increases. The cement having undergone the hydration reaction has a low specific gravity and causes a decrease in strength, so that the quality is inferior.

Further, when examining the density, the density of ordinary Portland cement is 3.16 g / cm ³ , whereas the density of the sludge fine powder described in Patent Document 1 is 2.21 to 2.39 g / cm ³ . small. The hydration reaction proceeds from the surface of the cement particles, but the low density is considered to be because the hydration reaction proceeds. Such a hydration reaction proceeds with the treatment time, but according to the recovery method described in Patent Document 1, the dehydrated cake is crushed to have a water content ratio of 50 to 60% by mass and a maximum particle size of 20 mm or less. The dried sludge is finely pulverized by an air pulverizer using wind power. In other words, since it is dried with a predetermined particle size when drying, the surface area of the granular object is not sufficiently large compared to the volume, and it takes time to dry. Drying must be stopped with a relatively high water content. That is, the object to be treated has a long time in a high temperature state where the hydration reaction of the cement proceeds rapidly. In this case, the hydration reaction proceeds even after being pulverized and dried by an air pulverizer, so that the density is low and the quality is considered to be low.

  Furthermore, from the point of view of the apparatus for carrying out the sludge recovery method, the recovery apparatus described in Patent Document 1 is a sediment that is not recognized as having an exceptional effect as an indispensable matter in the configuration of the invention. Since the tank is provided, the apparatus is expensive as a whole. Moreover, the pulverizing means for pulverizing the dehydrated cake, the drying means for drying the dehydrated cake crushed by the pulverizing means to 50 to 60% by mass, and the dry sludge dried by the drying means are finely pulverized by wind force. Since the pulverizing means is provided as a constituent element of the invention, it is further expensive.

  Accordingly, the present invention provides a method for recovering a high-grade concrete sludge fine powder, that is, a concrete sludge fine powder capable of obtaining a high-grade concrete sludge fine powder having a high cement content that has not undergone hydration, and an inexpensive facility, and It aims at providing the collection | recovery apparatus used for implementation of this collection | recovery method. Another object of the present invention is to provide high-quality concrete sludge fine powder suitable for reuse.

  The above object of the present invention is achieved by applying a rotary dryer or rotary dryer. According to this rotary dryer, crushing, crushing, and drying can be performed substantially simultaneously. Thereby, a high-quality concrete sludge fine powder can be obtained. Also, the equipment or facility costs are low.

  That is, in order to achieve the above object, the invention according to claim 1 is a slurry-like object to be treated such as residual concrete or return concrete to which predetermined water is added, or washing waste water generated from a ready mixed concrete factory. A process for obtaining a dehydrated cake by treating the slag, and a concrete sludge fine powder recovery method comprising a crushing / drying step of drying while crushing the dehydrated cake obtained by carrying out the treatment step, wherein the treatment step comprises: Separating the gravel and sand in the slurry-like object to be processed to obtain sludge water having a sand content of 10% by mass or less; and fine sand content from the sludge water obtained by the wet cyclone in the separation process The fine sand content removing step for separating and removing the water and the concentrated sludge water obtained by the fine sand content removing step through a filter press The dewatering cake manufacturing process which obtains 25-45 mass% dewatering cake, The said crushing and drying process supplies the dewatering cake obtained by the said dewatering cake manufacturing process continuously from one edge part of a rotating drum. The dewatered cake to be supplied is scooped up to a predetermined height by a lifter provided on its inner peripheral wall, dropped, and crushed by a crushing stirring blade provided in its inner space, at this time one end Then, the dewatered cake is crushed and dried substantially simultaneously, and the concrete sludge fine powder is continuously obtained from the other end. Invention of Claim 2 is comprised in the collection | recovery method of Claim 1 so that a dehydrating cake may be continuously supplied to a rotating drum with a mechanical fixed-quantity feeder at the time of the said crushing / drying process, The invention according to claim 3 is the recovery method according to claim 1 or 2, wherein at the crushing / drying step, a part of the exhaust gas from which the concrete sludge fine powder is recovered is mixed into the combustion gas by the burner. It is configured to blow hot air.

  The invention according to claim 4 is a processing apparatus for processing a slurry-like object such as residual concrete or return concrete to which predetermined water has been added, or washing waste water generated from a ready-mixed concrete factory to obtain a dehydrated cake. And a concrete sludge fine powder recovery device comprising a crushing / drying device for drying while crushing the dewatered cake obtained by the processing device, wherein the processing device comprises gravel and sand in the slurry-like workpiece A predetermined mesh vibrating sieve, a wet cyclone further removing fine sand from the mesh of the vibrating sieve, and a filter press for further concentrating the wet cyclone overflow, A horizontal rotary drum of a predetermined length in the axial direction to which dehydrated cake is continuously supplied, and hot air is blown into the rotary drum It consists of a hot stove and a bag filter that filters the exhaust gas discharged from the rotating drum, and the internal space of the rotating drum is provided with a plurality of crushing and stirring blades attached to a rotating shaft in the axial direction. In addition, the inner peripheral wall is provided with a lifter for scooping up the supplied dehydrated cake to a predetermined height and dropping it, and the filter is separated by the vibrating sieve so that the sand content is 10% by mass or less. Thus, a dehydrated cake having a moisture content of 25 to 45% by mass is obtained. According to a fifth aspect of the present invention, there is provided the collecting apparatus according to the fourth aspect, wherein the vibrating sieve is composed of sand and two sieves for sand, so that gravel and sand are collected separately, and According to a sixth aspect of the present invention, in the recovery apparatus according to the fourth or fifth aspect, the rotating shaft is provided at a position displaced from the axial center. Invention of Claim 7 is concrete sludge fine powder collect | recovered by implementation of the collection | recovery method of any one of Claims 1-3, Comprising: This fine powder contains 45-65 mass of at least calcium oxide. %, Silicon dioxide 15 to 30% by mass, and a specific surface area of 4000 to 15000.

The reason why the configuration of the invention is limited as described above will be described below.
Reasons for separation so that the sand content is 10% by mass or less in the separation process: residual concrete or return concrete to which predetermined water is added, or washing waste water generated from ready-mixed concrete factories, etc. The slurry-like object to be processed has a sand content not constant and is 5 to 20% by mass. When the sand content rate is varied in this way, the quality of the concrete sludge fine powder obtained in the subsequent step varies from the sludge water obtained in the separation step. The smaller the sand content in the sludge water, the higher quality concrete sludge fine powder can be obtained. However, it has been found that there is no practical problem if it is separated to 10% by mass or less. Considering it, it was determined as 10% by mass or less.

  The reason why it was determined to obtain a dehydrated cake having a moisture content of 25 to 45% by mass in the dehydrated cake manufacturing process: the moisture content is represented by (initial mass-absolutely dry mass) / initial mass × 100, The relationship with the water content is “moisture content = water content ratio / (water content ratio + 1)”. The smaller the moisture content and the more constant it is, the more advantageous for the subsequent drying process. However, if a dehydrated cake with a low moisture content is to be obtained, a filter press that can be processed at a high pressure is required. Become high. In addition, the time for obtaining the dehydrated cake becomes longer, and the processing capacity decreases. By the way, according to the present invention, the dehydrated cake is supplied to the horizontal rotating drum and dried while being crushed. In other words, the dehydrated cake is dried at a stretch with hot air while increasing the surface area of the dehydrated cake, so the moisture content is not significantly affected. . Therefore, considering the cost, processing capacity, etc. during the manufacturing process of the dehydrated cake, it is set within a moderate range of 25 to 45 mass%.

  During the crushing and drying process, 25 to 45 mass% dehydrated cake is continuously supplied from one end of the rotating drum, and the supplied dehydrated cake is sprinkled to a predetermined height by a lifter provided on the inner peripheral wall thereof. The reason for adopting ... is generally: The dehydrated cake is crushed before being dried. This is because when crushed, handling such as storage and transportation becomes convenient compared to large dehydrated cakes. However, when crushing and drying are performed in separate steps, the processing time becomes long and the workpiece may be deteriorated. That is, the hydration reaction proceeds, the density decreases, and the quality decreases. Moreover, although it is crushed, the thermal efficiency or drying efficiency when drying with hot air is not necessarily high. Furthermore, from the viewpoint of equipment, a drying device is required in addition to the crushing device, which increases costs. Therefore, the present invention is configured to perform crushing and drying substantially simultaneously. Moreover, in order to process continuously, the drum which throws in a dewatering cake was made into the horizontal rotation type. By adopting the horizontal type, the dewatered cake can be continuously supplied from one end, and the product concrete sludge fine powder can be continuously taken out from the other end. By using a rotary type, crushing and drying can be promoted. Moreover, in order to be able to carry out crushing and drying at the same time, a dewatering cake was scooped up and dropped in the rotating drum, and hot air was blown directly onto the falling dewatering cake. At this time, the falling dehydrated cake was also crushed and crushed.

  As described above, according to the present invention, since the sludge water having a sand content of 10% by mass or less is obtained in the separation step in the treatment process, even if the sand content of the slurry-like object to be processed is different, it is uniform. High quality concrete sludge fine powder can be recovered. In addition, since the fine sand content is removed from the sludge water by the fine sand content removal step before being subjected to the filter press, it becomes possible to produce a dehydrated cake with high cement content and high quality in the subsequent steps. . Furthermore, since a dehydrated cake having a moisture content of 25 to 45% by mass is obtained, that is, the range of the moisture content required for the dehydrated cake is relatively wide, the dehydrated cake can be produced easily and in large quantities.

  During the crushing and drying process, the dehydrated cake is continuously supplied from one end of the rotating drum, the supplied dehydrated cake is scooped up to a predetermined height by a lifter provided on the inner peripheral wall, and dropped, Crushing with a crushing stirring blade provided in the internal space, hot air is blown from one end at this time, crushing and drying of the dehydrated cake is carried out substantially simultaneously, and continuously from the other end In other words, since the concrete sludge fine powder is obtained, in other words, the dehydrated cake is pulverized to increase the contact area with the hot air and dried, so that the thermal efficiency is high and the drying processing time is short. Since the hydration reaction proceeds rapidly when the temperature of the cement is high, if the treatment time for drying is long, the time during which the material to be treated becomes high in water will become longer and the hydrate will be rapidly hydrated. The reaction proceeds. However, according to the present invention, since the drying treatment time is short, the progress of the hydration reaction during drying can be sufficiently suppressed. Therefore, the ignition loss is small, and an effect peculiar to the present invention that a high-density concrete sludge fine powder can be recovered can be obtained. Moreover, according to another invention, since exhaust gas is partly mixed with the hot air, the oxygen concentration in the hot air is small and deterioration of the concrete sludge fine powder can be suppressed.

  From the point of view of the recovery device, the water content of the dewatered cake is relatively rough, such as 25 to 45% by mass, so that it can be handled by an inexpensive filter press and the supply pressure of sludge water can be reduced. Furthermore, since the crushing device and the drying device are used in common, the entire recovery device can be made compact and inexpensively provided.

It is a block diagram which shows typically the process or apparatus until the dehydrated cake of the concrete sludge fine powder collection process or collection | recovery apparatus which concerns on embodiment of this invention is obtained. It is a figure which shows typically the crushing / drying apparatus after obtaining the dewatering cake of the collection apparatus of the concrete sludge fine powder which concerns on embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the horizontal type rotary dryer based on embodiment of this invention, The (a) is a side view which shows a whole by making a part into a cross section, The (a) was seen in the arrow ea direction in (a) Sectional drawing, (c) is an enlarged front view showing a part of a crushing stirring blade. It is a block diagram which shows the collection | recovery apparatus of the conventional concrete sludge fine powder.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. The recovery apparatus or recovery process according to the present embodiment is roughly classified into a processing apparatus or a processing process for processing a slurry-like object, and a crushing / drying apparatus for drying while crushing a dehydrated cake obtained by the processing process. Or it consists of a crushing and drying process. The slurry-like workpiece is a slurry obtained by adding a predetermined amount of water to residual concrete or return concrete, or washing waste water generated from a ready-mixed concrete factory.

  As shown in FIG. 1, the treatment apparatus 1 includes a pushed water storage tank 2, a first vibrating sieve 3, a spiral feeder 4, a second vibrating sieve 5, an under water tank 6, a supply water tank 7, a recycled cement. A sludge circulating water tank 8, a wet cyclone 10, a third vibrating sieve 9, a sludge water tank 11 for recycled cement, a filter press 12, and the like. A slurry-like workpiece including gravel, sand, sludge, and the like is sequentially pumped between these devices by a pump (not shown) and is sequentially processed. Alternatively, they are sequentially sent to a lower apparatus in a cascade manner by gravity and processed.

  The pushed water storage tank 2 stores rainwater, groundwater, etc. that has fallen into the ready mixed concrete factory. This water is the water that pushes the residual concrete discharged from the mixer truck M to a predetermined chute and sends it to the first vibrating sieve 3. Since the fluidity is high, subsequent processing becomes easy. The washing waste water of the ready mixed concrete factory is once loaded on the mixer truck M and then sent to the first vibrating sieve 3 via a predetermined chute. Since the fluidity is high, no water is required.

  The first vibrating sieve 3 is an apparatus that first processes a slurry-like object to be processed, and is composed of upper and lower two-stage sieves arranged at an inclination. The slurry-like object to be processed is separated by the first vibrating sieve 3 in the process of being sent by vibration and gravity. For example, a foreign substance having a diameter of 25 mm or more, that is, a so-called glass is contained in the upper sieve. For example, gravel having a diameter of 7 mm to 25 mm is separated. The so-called net under the screen is sludge water containing sand and fine sand. The separated glass is discharged into the glass box 3c and processed as industrial waste, but the gravel is washed with a predetermined washing water and then sent to the gravel bottle 3b to be used as a concrete material. Become. As the washing water, the separated water separated by the filter press 12 described later can be used. The screen below the first vibrating screen 3 is sent to the spiral feeder 4. As is well known in the art, the spiral feeder 4 includes a cylindrical mesh having a mesh smaller than the diameter of sand and a screw that is driven to rotate within the mesh. Therefore, under the mesh of the first vibrating screen 3 sent to the spiral feeder 4, the sand is separated by the net in the process of being sent by the screw, and the sand is sent to the second vibrating screen 5. On the other hand, the sludge water containing fine sand under the mesh of the spiral feeder 4 is supplied to the under water tank 6.

  The 2nd vibration sieve 5 consists of a 1 step | paragraph sieve arrange | positioned on a plane, is comprised so that sand may be sent by vibration, and wash water is poured from the upper part. Accordingly, washed sand is obtained, and water containing fine sand is obtained under the net. The collected sand is transported and stored in the sand yard 5b by a belt conveyor and used as a concrete material as appropriate. Under the net is sent to the underwater tank 6.

  Sludge water containing fine sand in the underwater tank 6 may be directly supplied to the wet cyclone 10 for processing, but in the present embodiment, it is once sent to the supply water tank 7 and then The wet cyclone 10 is supplied. The wet cyclone 10 separates solids and liquids according to the difference in specific gravity as conventionally known, and can separate and remove fine sand from sludge water. Overflow of the wet cyclone 10, that is, sludge water is sent to the sludge circulating water tank 8, but underflow having a large specific gravity and containing fine sand is sent to the third vibrating sieve 9. The third vibrating sieve 9 is a sieve made of, for example, a 1 mm mesh, and has a mesh suitable for washing the cement from fine sand to which the cement is adhered. The sand on the screen of the third vibrating screen 9 is sent to the second vibrating screen 5 to collect sand, and the bottom of the screen is sent to the underwater tank 6 to be circulated. The fine sand will be removed. The sludge circulating water tank 8 for recycled cement stores the sludge water treated as described above. The sludge water is used for the residual concrete discharged from the mixer truck to the first vibrating sieve 3. It may be used as appropriate for pushing water to be pushed away or sent to the supply water tank 7 to be supplied to the wet cyclone 10. Thus, the sludge water stored in the sludge circulation water tank 8 circulates in the treatment apparatus 1, but by repeating the circulation, fine sand is removed and sludge water having a high concentration of cement is obtained. become. When a predetermined concentration is reached, the sludge water is sent from the sludge circulating water tank 8 to the sludge water tank 11. In the sludge water tank 11, if necessary, a retarder can be mixed to delay the progress of the cement hydration reaction. Sludge water is sent batchwise from a sludge tank 11 to a filter press 12, and a dehydrated cake is produced. The press pressure is adjusted to obtain a dehydrated cake having a predetermined moisture content.

  A conventionally known filter press 12 is applied to obtain a dehydrated cake having a moisture content of 25 to 45% by mass. The dehydrated cake is soft because it has a relatively high water content, and when it is put into a crushing / drying apparatus 20 described later, it is thrown in while being crushed by a metering feeder formed on a spiral.

  The obtained dehydrated cake is supplied to the crushing / drying device 20 with a wheel loader as it is without being crushed as shown in FIG. As shown in FIG. 3, the crushing / drying device 20 is composed of a rotary dryer RD and related devices as described below.

  Various types of dryers can be applied to the rotary dryer RD as long as it has a crushing stirring blade inside and can blow hot air, but a horizontal type is desirable for continuous processing. . A specific embodiment thereof is shown in FIG. According to the present embodiment, the horizontal rotary drum 21 is supported and rotated at two locations. That is, a ring-shaped rail 22 is provided on the outer peripheral portion in the vicinity of one end of the rotating drum 21, and this rail 22 is rotatably supported by a plurality of rollers 23. A ring-shaped or rack-shaped gear 25 is attached to the outer peripheral portion from the other end. A pinion 27 driven by a motor 26 is engaged with the gear 25. Accordingly, the rotary drum 21 is rotationally driven by the motor 26 in a predetermined direction.

  As shown in FIG. 3A, a rotating shaft 30 that is driven at a relatively high speed is provided in the rotating drum 21 at a position offset from the shaft center. A plurality of crushing stirring blades 31 are attached to the rotating shaft 30. As shown in the enlarged view of FIG. 3C, the crushing stirring blade 31 has an arm 32 extending radially outward from the rotary shaft 30 and a predetermined interval in the radial direction between the arm 32 and the arm 32. It is composed of a plurality of rod-shaped wings 33, 33,. A plurality of such crushing and stirring blades 31 are attached around the rotary shaft 30 at a predetermined angle, for example, at an interval of 120 degrees and at a predetermined distance in the axial direction.

  Further, a plurality of scraping blades, that is, lifters 35, 35,... These lifters 35, 35,... Are composed of a vertical portion 35 a that is directed to the center of rotation and an inclined portion 35 b that is bent from the vertical portion 35 a in the rotation direction of the rotary drum 22. Accordingly, when the rotary drum 21 is driven in the direction of arrow A in FIG. 3A, the dewatered cake K is scooped up and dropped halfway. Such vertical portion 35a and inclined portion 35b are integrally formed from a plate-like member, and are provided over the entire length of the rotating drum 21, as shown in FIG.

  The rotating drum 21 configured as described above has a dehydrated cake supply side on the left side and a concrete sludge fine powder collection side on the right side in FIG. A hopper 40 is provided on the supply side. Since a mechanical quantitative feeder 41 is provided at the lower portion of the hopper 40, the dehydrated cake carried into the hopper 40 is continuously supplied to the rotary drum 21 by the quantitative feeder 41. The fixed amount feeder 41 is a conventionally known rotary feeder or screw feeder. The rotary feeder has a rotating shaft to which a plurality of blades are attached at regular intervals. Therefore, when the rotary shaft is rotationally driven at a predetermined speed, the dewatered cake sandwiched between the blades is supplied to the rotary drum 21 in proportion to the rotational speed of the rotary shaft. Also in the screw feeder, the dewatered cake is sandwiched between the flights of the screw so that the dehydrated cake is fed to the rotating drum 21 when the screw shaft is driven at a predetermined speed. With these mechanical quantitative feeders 41, the lump dehydrated cake is supplied into the rotary drum 21 while being crushed. Note that the chute 42 of the metering feeder 41 faces the inside of the rotary drum 21. The tip of the chute 42 appears in FIG.

  On the supply side of the rotary drum 21, a burner 51 that is supplied from an oil supply tank 50 and burns, for example, heavy oil is also provided. The air heated by the combustion heat of the burner 51, the combustion exhaust gas, and a part of the exhaust gas to be described later are continuously supplied from the hot stove 52 to the rotary drum 21.

  An exhaust hood 45 is provided on the collection side of the rotary drum 21. The cross-sectional area of the upper part of the exhaust hood 45 is sufficiently wide. Therefore, the speed of the gas sent from the rotary drum 21 to the exhaust hood 45 is sufficiently slow in the exhaust hood 45. Thereby, the concrete sludge fine powder settles on the bottom of the exhaust hood 45 by gravity. A screw conveyor 46 connected to the product storage bin 60 is provided at the lower end of the exhaust hood 45.

  As shown in FIG. 2, a bag filter 48 sucked by the suction fan 49 is connected to the downstream side of the exhaust hood 45. The concrete sludge fine powder collected by the bag filter 48 is sent to the product storage bin 60 by the screw conveyor 46. A part of the exhaust gas downstream of the bag filter 48 is returned to the hot stove 42.

  The crushing / drying device 20 operates as follows. The dehydrated cake K obtained as described above is sent to the fixed amount supply hopper by the wheel loader, and the dehydrated cake K leveled and supplied by the fixed amount supply hopper is carried into the hopper 40 by the belt conveyor. The dewatered cake K is continuously supplied to a predetermined amount of the rotating drum 21 by a mechanical quantitative feeder 41. The rotary drum 21 is driven to rotate and the rotary shaft 30 is driven to rotate at a high speed. Further, hot air is supplied from the hot air furnace 52 into the rotary drum 21. The temperature of the hot air is 80 to 150 ° C, more preferably 100 to 140 ° C, and still more preferably 110 to 140 ° C. Then, the dewatered cake K that has been crushed by the constant amount feeder 41 and is thrown up is lifted by the lifters 35, 35,. The dewatered cake K is mainly crushed by the crushing stirring blades 31, 31,... That are rotationally driven at a high speed when falling, and comes into contact with hot air. Such an action continues from the supply side to the discharge side of the rotary drum 21. The bulk dehydrated cake K is gradually pulverized and dried in the course of being sent from the supply side to the discharge side. When reaching the discharge end, the dewatering cake K is being crushed, and falls from the lifters 35, 35,. The dehydrated cake falling in the form of an air curtain and hot air are in direct contact with each other and dried to form concrete sludge fine powder.

  The exhaust gas containing the concrete sludge fine powder is sent to the exhaust hood 45 by the hot air sent from the hot air furnace 52. By the exhaust hood 45, the concrete sludge fine powder settles as described above, and is pumped to the product storage bin 60 by the screw conveyor 46. Further, the concrete sludge fine powder collected by the bag filter 48 is also sent to the product storage bin 60 by the suction force of the suction fan 49 provided on the downstream side of the bag filter 48. At this time, part of the exhaust gas is returned to the hot stove 52. The concrete sludge fine powder stored in the product storage bottle 60 is transported to a predetermined place by a loose wheel as shown in FIG. Or precomp pack.

  According to the present embodiment, various effects can be obtained. For example, due to the synergistic effect of the rotation of the rotating drum 21 and the high-speed rotation of the crushing stirring blades 35, 35,. In addition, since the dehydrated cake is dried with hot air while being crushed, that is, the contact area with the hot air is increased for drying, the thermal efficiency is high. Since a part of the exhaust gas is mixed in the hot air, the oxygen concentration in the hot air is small and the deterioration of the concrete sludge fine powder is small. Furthermore, the amount of exhaust gas released into the atmosphere is reduced.

The following test for confirming the effectiveness of the method for recovering the concrete sludge fine powder according to the present embodiment was performed.
As the slurry-like object to be treated, a mixture of residual concrete obtained at the applicant's factory and washing waste liquid from the mixer truck was used. The processing apparatus 1 which concerns on this Embodiment was used for the collection apparatus of concrete sludge fine powder. The conditions of each device are as follows.
First vibrating sieve 3: a two-stage sieve in which the upper sieve has an opening of 25 mm and the lower sieve has an opening of 7 mm.
Second vibrating sieve 5: A sieve having an opening of 0.7 mm. Made by Ando Screen Production Co., Ltd.
Third vibrating sieve 9: A sieve having an opening of 1.0 mm.
Wet cyclone 10: Product TC-12 manufactured by Tama Cyclone Co., Ltd. is used.
Filter press 12: A product TKD-400ASWD manufactured by Tomec Co., Ltd. is used.
Rotary dryer RD: manufactured by Okawara Manufacturing Co., Ltd. The rotation speed of the rotating drum 21 is 3.07 rpm, the rotation speed of the crushing stirring blade 31 is 304 rpm, and the hot air supplied into the rotating drum 21 is 100 to 140 ° C.

  The test situation is as follows. When it processed with the processing apparatus 1 which concerns on this Embodiment, the sludge water whose sand content rate is 7.63 mass% in the sludge water tank 11 was obtained. From this sludge water, a dehydrated cake having a water content of 29.2% was obtained by a filter press 12. The sand content rate was measured by the method for testing the sand content rate in the sludge solid content of the National Federation of Ready-mixed Concrete Industries Association (ZKT-103). The dehydrated cake thus obtained was supplied to a rotary dryer RD to obtain a product S1. This was requested to Environmental Management Center Co., Ltd., and component analysis was performed by a test method such as JIS R 5202 8. The results are shown in S1 of Example 1 in Table 2 alongside normal Portland cement and some components of conventional products for easy comparison.

  From the above Example 1, when the concrete sludge fine powder recovery method according to the present embodiment is carried out, the loss on ignition is small, the amount of calcium oxide is large, the density is large, and high quality concrete sludge fine powder is obtained. It turned out to be obtained. Furthermore, it has been found that a sufficiently high quality can be obtained only by dehydrating the water content to about 25%. It is considered preferable from the viewpoint of cost. However, if the water content is high, the drying process takes time, and the hydration reaction proceeds and the quality is likely to deteriorate. Therefore, it is estimated that about 45% is practically the upper limit. In addition, when the experiment was further performed twice under substantially the same conditions, S2 and S3 of Examples 2 and 3 were obtained. The moisture contents of Examples 2 and 3 when the dehydrated cake was formed in the filter press 12 were 42.1% and 25.8%, respectively. In Examples 2 and 3, S2 and S3 were small in ignition loss, large in calcium oxide, large in density, and high quality concrete sludge fine powder.

DESCRIPTION OF SYMBOLS 3 1st vibration sieve 5 2nd vibration sieve 9 3rd vibration sieve 10 Wet cyclone 12 Filter press 21 Rotary drum 31 Crushing stirring blade 35 Lifter 52 Hot stove

Claims (7)

It is obtained by processing a slurry-like material to be processed such as residual concrete or return concrete to which predetermined water has been added, or washing waste water generated from a ready-mixed concrete factory, to obtain a dehydrated cake; A method for recovering fine powder of concrete sludge comprising a crushing and drying step of crushing and drying a dehydrated cake to be produced,
The treatment step includes a separation step of separating the gravel and sand in the slurry-like workpiece to obtain sludge water having a sand content of 10% by mass or less, and sludge water obtained by the separation step using a wet cyclone. A fine sand content removing step for separating and removing fine sand content from the slurry, and a dehydrated cake manufacturing step for obtaining a dehydrated cake having a moisture content of 25 to 45 mass% by subjecting the concentrated sludge water obtained by the fine sand content removal step to a filter press And consist of
In the crushing / drying step, the dehydrated cake obtained in the dehydrated cake manufacturing step is continuously supplied from one end of the rotary drum, and the supplied dehydrated cake is supplied by a lifter provided on the inner peripheral wall thereof. While scooping up to a predetermined height and dropping it, it is crushed by a crushing stirring blade provided in its internal space, and hot air is blown from one end at this time, and crushing and drying of the dehydrated cake are substantially simultaneously performed. A method for recovering concrete sludge fine powder, which is carried out and obtains concrete sludge fine powder continuously from the other end. 2. The method for recovering fine concrete sludge powder according to claim 1, wherein the dewatered cake is continuously supplied to a rotating drum by a mechanical quantitative feeder during the crushing / drying step. 3. The recovery method according to claim 1 or 2, wherein in the crushing / drying step, the concrete sludge fine blown with hot air of 100 to 140 [deg.] C. in which a part of the exhaust gas from which the concrete sludge fine powder has been collected is mixed into the combustion gas by the burner. Powder recovery method. A processing device that obtains a dehydrated cake by processing a slurry-like workpiece such as residual concrete or return concrete to which predetermined water has been added, or washing waste water generated from a ready mixed concrete factory, and dehydration obtained by the processing device A concrete sludge fine powder recovery device consisting of a crushing and drying device that dries while crushing the cake,
The processing apparatus includes a predetermined mesh vibrating screen that separates gravel and sand in the slurry-like workpiece, a wet cyclone that further removes fine sand from the net of the vibrating screen, and an overflow of the wet cyclone. It consists of a filter press that further concentrates,
The crushing / drying apparatus filters a horizontal rotary drum having a predetermined length in the axial direction to which dehydrated cake is continuously supplied, a hot air furnace for blowing hot air into the rotary drum, and an exhaust gas discharged from the rotary drum. A bug filter that
In the internal space of the rotating drum, a plurality of crushing and stirring blades attached to the rotating shaft in the axial direction are provided, and the dehydrated cake supplied to the inner peripheral wall is scooped up to a predetermined height, And there is a lifter to drop,
A concrete sludge fine powder recovery apparatus, wherein the slurry is separated so as to have a sand content of 10% by mass or less by the vibrating sieve, and a dewatered cake having a water content of 25 to 45% by mass is obtained by the filter press. 5. The recovery device according to claim 4, wherein the vibrating screen is made up of sand and two sand screens, and gravel and sand are recovered separately. 6. The recovery device according to claim 4 or 5, wherein the rotating shaft is provided at a position displaced from an axial center. The concrete sludge fine powder recovered by carrying out the recovery method according to any one of claims 1 to 3, wherein the fine powder is at least 45 to 65 mass% of calcium oxide and 15 to 30 mass of silicon dioxide. % Concrete sludge fine powder having a specific surface area of 4000-15000.

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