JP4042008B2 - Cement dust treatment method and apparatus - Google Patents

Description

【００４８】
表１に示されているように、第２段液分は各種の規制値を満足しているので、廃水としてそのまま放流することができる。
【００４９】
比較例１
実施例１で得られた第２段濃縮物を、実施例１において混合濃縮物の固液分離に使用した濾過機で固液分離を試みたが、該第２段濃縮物に含有されている固形分の性質に起因して固液分離が困難であった。
さらに、濾過機以外の各種の固液分離手段を使用して前記の第２段濃縮物の固液分離を試みたが、矢張り、固液分離が困難であった。
【００５０】
【発明の効果】
本発明によって不溶化された鉛成分などの第二重金属成分を含有するスラリーから、不溶化された鉛成分などの第二重金属成分を通常の固液分離手段のみによって容易に分離することができ、しかも各種の規制値を満足する排水しか排出されないので、環境を汚染する危険性は全くない。
【図面の簡単な説明】
【図１】本発明のセメントダスト処理装置の代表例のフローシートである。
【符号の説明】
1 セメントダスト水洗槽
11 セメントダスト供給管
12 給水管
13 第１段スラリー排出口
14 スラリー移送管
15 攪拌機
2 凝集沈降槽
21 第１段液分排出口
22 第１段濃縮物排出口
23 液分移送管
231 酸性物質供給管
24 濃縮物移送管
25 集泥レーキ
3 不溶化槽
31 硫化剤供給管
32 第２段スラリー排出口
33 スラリー移送管
34 攪拌機
4 凝集沈降槽
41 第２段液分排出口
42 第２段濃縮物排出口
43 液分移送管
431 貯槽
432 ポンプ
433 管
4331 弁
434 分岐管
4341 弁
435 分岐管
4351 弁
44 濃縮物移送管
441 ポンプ
45 集泥レーキ
5 管
51 ポンプ
6 濾過機
61 液排出口
62 固形物排出口
63 液移送管
631 分岐管
6311 弁
632 分岐管
6321 弁
6322 弁
64 コンベヤ
65 洗浄水供給管
66 排水口
661 液移送管
7 オートサンドフィルタ
71 洗浄排水口
72 濾過水排出口
73 洗浄排水管
731 弁
8 排水管
81 弁
82 分岐管
821 弁
M 電動機[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for treating cement dust, and more particularly, it is easy to separate a solid from a slurry containing an insolubilized harmful heavy metal component when separating the harmful heavy metal component from cement dust. The present invention relates to a method and apparatus for treating cement dust.
[0002]
[Problems to be solved by the invention]
Cement is widely used for ready-mixed concrete, various cement products, architecture, civil engineering, roads, bridges, railways, harbors and households, and its production and usage are also increasing.
Cement typified by Portland cement is usually mixed with various admixtures such as silica, steel slag and fly ash in limestone and clay, which are the main raw materials, and this mixture is pulverized and melted to obtain a clinker. After the clinker is quenched, a small amount of gypsum is mixed and the mixture is pulverized.
[0003]
In the production of this cement, each of the chlorine component and alkali component contained in a large amount in the main raw material has an adverse effect on the clinker, and various troubles such as condensation at the low temperature place occur in the production process. Has been known since early. In addition, heavy metal components such as cadmium and lead contained in the main raw material are mixed in dust accompanying the extraction from the firing furnace (hereinafter referred to as extraction accompanying dust), and the environment is contaminated during the processing of this dust. Will be.
[0004]
As described above, the amount of lime used as the main raw material has been steadily increasing with the increase in the production amount of cement.
Therefore, in recent years, a large amount of incineration ash from various types of waste such as industrial waste and municipal waste is mainly used to conserve resources, effectively use waste, and extend the period of use of waste disposal sites. Used in raw materials.
Along with a large amount of incineration ash of such various wastes, due to the chlorine component, alkali component and heavy metal component contained in the incineration ash, the chlorine component of the extraction entrained dust, The contents of alkali components and heavy metal components are also increasing.
[0005]
In order to remove the alkali component and the chlorine component contained therein from the bleed air accompanying dust, the bleed air accompanying dust is usually washed with water. This washing drainage liquid is usually strongly alkaline having a pH of about 12-13. Therefore, almost all of the cadmium component contained in the extraction entrained dust is insolubilized and precipitated in the water washing, and the concentration of dissolved cadmium in the water washing wastewater becomes extremely low, which is less than the wastewater regulation value.
[0006]
On the other hand, since the solubility of lead is large at a pH of about 12 to 13, it is dissolved in a large amount without being insolubilized in the above washing drainage solution, and the dissolved concentration of lead in the washing drainage solution is 0.1 mg / l of the wastewater regulation value. Will be exceeded. Therefore, the lead component dissolved in the washing drainage liquid is removed by adjusting the pH of the washing drainage liquid to about 9 to insolubilize and precipitate the lead component.
As a method for removing the chlorine component, alkali component, heavy metal component and the like contained in the extraction entrained dust by washing the extraction entrained dust with water, for example, JP-A-6-1557089 and JP-A-9-295841, respectively. There is a method described in.
[0007]
Japanese Laid-Open Patent Publication No. 6-1557089 discloses a process in which dust extracted from a cement kiln is made into a primary slurry adjusted to a pH optimum for precipitation of a first obstacle substance such as cadmium in the extracted dust. And a step of converting the liquid content of the primary slurry to a second slurry adjusted to a pH optimum for precipitation of the second obstacle such as lead, and further, if desired. A kiln dust treatment system is described in which a precipitation accelerator such as sodium sulfide and hydrogen sulfide is further added to the primary slurry.
[0008]
In Japanese Patent Laid-Open No. 9-295841, water is added to a bleed entrained dust originally containing a specific amount or more of sulfur as a sulfide to form a slurry, and the slurry is solid-liquid separated according to the amount of sulfide. It is characterized by solid-liquid separation after the dissolved liquid phase or the slurry itself without solid-liquid separation is adjusted to pH 8.5 to 11.0 to precipitate dissolved harmful substances such as lead. A method for treating bleed dust is described. Thus, in this method, the kiln dust treatment system described in the above-mentioned Japanese Patent Application Laid-Open No. 6-1557089, if desired, for example, when adding a precipitation accelerator such as sodium sulfide and hydrogen sulfide, Since there are disadvantages that require cost, etc., there is a method for eliminating this disadvantage, and the sulfides in this method are not sulfides such as sodium sulfide and hydrogen sulfide added intentionally, but instead of sulfides such as cement. Part of the sulfur oxide contained in the main raw material is produced by reduction in a reducing atmosphere, and the amount is controlled by controlling the amount of calcium oxide accompanying the extraction gas It is said to be a thing.
[0009]
The inventors of the present invention made precipitates by insolubilizing harmful heavy metal components such as cadmium components and lead components from slurry obtained by washing cement dust such as bleed entrained dust with water, separating and removing the precipitates, In order to make the concentration of these heavy metal components in the wastewater less than the regulation value, the above-described conventional technology was examined. As a result, the pH of the liquid separated from the slurry obtained by washing the cement dust with water is adjusted to be almost neutral to weakly alkaline, and then mixed with a sulfiding agent to dissolve lead in the liquid. Insolubilize heavy metal components such as components to form solids, convert this liquid into a slurry, and separate the solids from this slurry by solid-liquid separation, the solids containing the insolubilized heavy metal components It is difficult to separate and remove solids from the slurry due to the nature of the minute. The concentrate obtained by separating the liquid from the slurry and the slurry obtained by washing the cement dust with water. The new knowledge that the solid can be easily separated and removed from the slurry by mixing with the concentrate from which the liquid was separated is obtained, and the present invention has been reached based on this new knowledge. Shi .
[0010]
[Means for Solving the Problems]
That is, according to the first aspect of the present invention, the slurry obtained by washing the cement dust with water is subjected to solid-liquid separation, the liquid component separated by the solid-liquid separation is adjusted to pH 7-9, and the pH-adjusted liquid component is obtained. A heavy metal component dissolved in the liquid is insolubilized by adding a sulfidizing agent to the solid to form a solid, and the liquid is made into a slurry, and the concentrate separated from the slurry and the cement A method for treating cement dust, comprising mixing a concentrate obtained by washing a dust with a slurry and separating the mixture from a slurry, and solid-liquid separation of the mixture.
[0011]
The second invention is an apparatus for use in the method for treating sentiment dust of the first invention.
That is, the first stage solid-liquid separation means for slurry from the cement dust washing tank, the pH of the liquid from the first stage solid-liquid separation means is adjusted to 7-9, and mixed with a sulfiding agent. An insolubilization tank for insolubilizing heavy metal components dissolved in the liquid component and a second stage solid-liquid separation means for slurry from the insolubilization tank are successively connected, and the first stage solid-liquid separation means is concentrated. Cement dust treatment, characterized in that the material transfer means and the concentrate transfer means of the second stage solid-liquid separation means are combined to form an integration means, and the integration means is connected to the solid-liquid separation means Device.
DETAILED DESCRIPTION OF THE INVENTION
[0012]
The cement dust in the present invention may be dust generated from a cement manufacturing apparatus and containing at least an alkali component, a chlorine component, and a heavy metal component such as a cadmium component and a lead component. Although it is processed, the dust discharged from each of the cooler and pulverizer of the cement manufacturing apparatus is also preferably processed.
[0013]
Cement dust is washed with water by a conventional method. The liquid obtained by washing with water usually has a pH of about 12 to 13, and has a high concentration of the alkali component, chlorine component, lead component and the like contained in the cement dust, and the cadmium component. Is a slurry insolubilized and contained as a solid content (this slurry is hereinafter referred to as a first stage slurry).
[0014]
The first stage slurry is preferably made into a concentrate by separating liquid components by solid-liquid separation means such as a coagulating sedimentation device and a gravity sedimentation device. First stage liquid fraction and first stage concentrate). The first stage concentrate is a slurry with a high solids concentration.
The first stage liquid is adjusted to neutral or weakly alkaline with a pH of about 7 to 9 by adding an acidic substance thereto. There is no restriction | limiting in particular in an acidic substance, Each of an organic acid and a mineral acid is used suitably, and a mineral acid is especially preferable. Typical examples of organic acids include oxalic acid and acetic acid, and representative examples of mineral acids include hydrochloric acid, nitric acid, and sulfuric acid. Of these, sulfuric acid is most preferred.
[0015]
A sulfurizing agent is added as a precipitation accelerator to the first stage liquid adjusted to a predetermined pH, and a heavy metal component such as a lead component dissolved in the liquid (this heavy metal component is hereinafter referred to as a second double metal component) The slurry is sulphided and insolubilized, and the liquid is made into a slurry containing the insolubilized second metal component (this slurry is hereinafter referred to as a second stage slurry). If the pH at this time is outside the range of 7 to 9, insolubilization of the second double metal component is insufficient.
[0016]
The sulfiding agent may be any substance that can be insolubilized by sulfiding the second double metal component, and is not particularly limited, but hydrogen sulfide and alkali metal sulfide are preferably used. Alkali metal sulfides include hydrosulfides. As a representative example of sulfide, sodium sulfide Na ₂ S and sodium hydrosulfide NaHS.
[0017]
The amount of sulfiding agent used varies depending on the type and concentration of the second double metal component dissolved in the first stage liquid and the type of the sulfiding agent, and cannot be specified in general, but it is dissolved in the first stage liquid. The stoichiometry must be greater than the stoichiometric weight of the second double metal component. For example, when the second double metal component is a lead component and the sulfiding agent is an alkali metal sulfide, the amount of the alkali metal sulfide used is usually 0.1 with respect to the weight of the liquid. About 2% by weight.
This pH adjustment and insolubilization is usually carried out at room temperature to room temperature, but does not interfere with heating or cooling.
[0018]
In the second-stage slurry, the liquid components are separated into concentrates (the liquid component and the concentrate are hereinafter referred to as the second-stage liquid component and the second-stage concentrate). For the separation of the second stage liquid, a coagulation sedimentation device or a gravity sedimentation device is preferably used. In order to promote sedimentation at this time, it is preferable to add a polymer flocculant to the second stage slurry. As the polymer flocculant, those known per se can be used. For example, an acrylamide-based cationic polymer flocculant is most preferable. The second stage concentrate thus obtained is a slurry with a high solids concentration.
[0019]
Since the second stage liquid usually satisfies all the various regulation values, it can be discharged as waste water as it is. However, if the second-stage liquid content does not satisfy any of the various regulation values, it can be discharged as waste water after undergoing various treatments such as filtration to satisfy these regulation values. Alternatively, it can be returned to the insolubilization step as it is or after the treatment.
The total amount of the second stage concentrate is mixed with the total amount of the first stage concentrate to form a mixture of both concentrates (hereinafter referred to as a mixed concentrate). The mixed concentrate is divided into a solid and a liquid. To be separated.
[0020]
For separation of the solid and liquid from the mixed concentrate, for example, solid-liquid separation means such as a centrifuge and a filtration device are preferably used. (Denoted as mixed solids) is a cake with a low water content.
When the content of the inorganic salt in the mixed solid is high, it is preferable to wash the mixed solid with water for the purpose of reducing the concentration of the inorganic salt, and it is particularly preferable to perform multi-stage washing. The washing waste water when the mixed solid is washed with water is preferable because the amount of new washing water can be reduced by using it as washing water for washing cement dust.
[0021]
The mixed solid separated from the mixed concentrate is usually reused after its entire amount is mixed with the main cement raw material.
In addition, the liquid separated from the mixed concentrate is usually mixed with the first stage liquid, but if this liquid satisfies all of the various regulation values, it can be discharged as waste water as it is. it can.
[0022]
In the apparatus of the present invention, the first-stage solid-liquid separation means and the second-stage solid-liquid separation means are preferably settling devices such as a coagulation settling device and a gravity settling device, respectively. Furthermore, the solid-liquid separation means connected to the integration means for solid-liquid separation of the mixed concentrate is preferably, for example, a centrifuge or a filtration device. These devices may be either a continuous type or a batch type, and those known per se can be used. The filtration device may be either a batch filtration device such as a filter press or a continuous filtration device such as a horizontal belt filtration device, but the latter is preferred.
The insolubilization tank in the apparatus of the present invention may be either a tank type or a tower type.
[0023]
In the apparatus of the present invention, a pipe is usually used as a means for moving the liquid (the means for moving is hereinafter referred to as “transfer means”, and the liquid transfer means is hereinafter referred to as “liquid transfer means”). If desired, for example, a pump such as a turbo pump can be interposed. In addition, as a means for transferring a slurry having a high solid concentration as a concentrate (hereinafter referred to as slurry transferring means), a pipe is usually used. For example, a turbo type pump or a positive displacement pump is used for the pipe as required. Or a slurry pump or the like can be interposed. Furthermore, a conveyor such as a belt conveyor, a bucket conveyor, and a screw conveyor is usually used as a transfer means (hereinafter referred to as solid transfer means) for cakes and solids having a low water content, which are concentrates.
[0024]
The integration unit is a slurry transfer unit because the mixed concentrate is a slurry. Moreover, tanks can be interposed in the transfer means as the integration means.
These transfer means are preferably used for continuously moving objects to be moved such as liquids, slurries, concentrates, cakes and solids, but also for moving the objects to be moved batchwise. can do.
[0025]
The solid-liquid separation means for separating the mixed concentrate into solid-liquid is connected to the liquid discharge port and the first stage liquid transfer means by the liquid transfer means, and optionally connected to a drain pipe. . On the other hand, the solid discharge port is connected to the cement manufacturing apparatus by a solid transfer means. Further, the solid matter obtained by the solid-liquid separation means is washed with water as desired. The drainage port of the washing wastewater of the solid-liquid separation means is connected to the cement dust washing tank and the liquid transfer pipe as the liquid transfer means. It may be preferable.
[0026]
Further, in the second stage solid-liquid separation means, the second stage liquid outlet is finally connected to the drain pipe by the liquid transfer means. Various cleaners such as a storage tank and a filtration device can be interposed in the liquid transfer means. As this filtration device, an auto sand filter (trade name, product of Tsukishima Kikai Co., Ltd.) is most preferable. The second stage liquid outlet can be finally connected to the insolubilization tank by the liquid transfer means.
The apparatus of the present invention can be operated continuously or batchwise.
[0027]
In the present invention, waste water that satisfies various regulatory values is finally discharged as waste water, and the total amount of solid matter containing insolubilized heavy metal components is mixed with the main raw material of sentiment and recycled. There is no risk of polluting the environment because it is used and not discharged outside the cement production equipment and the cement dust treatment equipment.
[0028]
【Example】
Examples The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
Example 1
A representative example of the cement dust treatment apparatus of the present invention will be described with reference to the drawings.
FIG. 1 is a flow sheet of a typical example of the cement dust treatment apparatus of the present invention.
[0029]
That is, a cement dust washing tank 1, a coagulation sedimentation tank 2 as a first stage solid-liquid separation means, an insolubilization tank 3, and a coagulation sedimentation tank 4 as a second stage solid-liquid separation means are successively connected in series. .
The cement dust washing tank 1 is provided with a cement dust supply pipe 11, a water supply pipe 12, and a first stage slurry discharge port 13. Thus, the first stage slurry discharge port 13 is connected to the coagulation sedimentation tank 2 by a slurry transfer pipe 14 which is a slurry transfer means. In addition, a stirrer 15 driven by an electric motor M is mounted inside the cement dust washing tank 1.
[0030]
The coagulation sedimentation tank 2 is provided with a first stage liquid outlet 21 and a first stage concentrate outlet 22, respectively. The first stage liquid outlet 21 is connected to the insolubilization tank 3 by a liquid transfer pipe 23 which is a liquid transfer means. An acidic substance supply pipe 231 is attached to the liquid transfer pipe 23. Further, a concentrate transfer pipe 24 which is a slurry transfer means is connected to the first stage concentrate discharge port 22. Thus, a mud collecting rake 25 driven by an electric motor M is mounted inside the coagulation sedimentation tank 2.
[0031]
The insolubilizing tank 3 is provided with a sulfiding agent supply pipe 31 and a second-stage slurry discharge port 32. This second stage slurry discharge port 32 is connected to the coagulation sedimentation tank 4 by a slurry transfer pipe 33 which is a slurry transfer means. The insolubilization tank 3 has an electric motor inside.
A stirrer 34 driven by M is installed.
[0032]
The coagulation sedimentation tank 4 is provided with a second stage liquid outlet 41 and a second stage concentrate outlet 42, respectively. A liquid transfer pipe 43 as a liquid transfer means is connected to the second stage liquid discharge port 41. A concentrate transfer pipe 44 as slurry transfer means is connected to the second stage concentrate discharge port 42. A pump 441 is interposed in the concentrate transfer pipe 44. Thus, a mud collecting rake 45 driven by an electric motor M is mounted inside the coagulating sedimentation tank 4.
[0033]
The concentrate transfer pipe 24 and the concentrate transfer pipe 44 are associated with each other to form a pipe 5 which is an integrated means. The pipe 5 is connected via a pump 51 to a filter 6 that is a solid-liquid separation means. The filter 6 is provided with a liquid discharge port 61 and a solid material discharge port 62. The liquid discharge port 61 and the solid matter discharge port 62 are connected to a liquid transfer pipe 63 that is a liquid transfer means and a conveyor 64 that is a solid matter transfer means, respectively.
Further, a cleaning water supply pipe 65 is connected to the filter 6. On the other hand, the drain 66 of the washing waste water after washing the solid material is connected to the cement dust washing tank 1 and the liquid transfer pipe 661.
[0034]
The liquid transfer pipe 63 is further branched into a branch pipe 631 and a branch pipe 632. These branch pipe 631 and branch pipe 632 are provided with a valve 6311 and a valve 6321 and a valve 6322, respectively. The liquid discharge port 61 of the filter 6 is finally connected to the liquid transfer pipe 23 by the liquid transfer pipe 63 and the branch pipe 631, and on the other hand, the liquid discharge pipe 63 and the branch pipe 632 finally Is connected to a drain pipe 8. Further, the solid material discharge port 62 of the filter 6 is connected to a cement production apparatus by a conveyor 64. However, the cement manufacturing apparatus is not illustrated. The filter 6 is provided with a washing water supply pipe 65. On the other hand, the drainage port 66 for washing waste water obtained by washing the solid with water is connected to the cement dust washing tank 1 and the liquid transfer pipe 661.
[0035]
A storage tank 431, a pump 432, and a pipe 433 are sequentially interposed in the liquid transfer pipe 43, and the pipe 433 is connected to an auto sand filter 7 that is a filter. A branch pipe 434 is branched from the pipe 433, and the pipe 433 is finally connected to the drain pipe 8 by the branch pipe 434. The branch pipe 434 is provided with a valve 4341.
[0036]
Further, a branch pipe 435 is branched from the pipe 433. The pipe 433 and the branch pipe 435 are provided with a valve 4331 and a valve 4351 on the downstream side of the branch point with the branch pipe 435, respectively.
The auto sand filter 7 is provided with a cleaning drain port 71 and a filtered water discharge port 72, respectively. A cleaning drain pipe 73 is connected to the cleaning drain port 71, and a valve 731 is provided in the cleaning drain pipe 73.
[0037]
A drain pipe 8 is connected to the filtrate outlet 72, and a valve 81 is provided in the drain pipe 8. A branch pipe 82 is branched from the drain pipe 8 on the downstream side of the valve 81, and the branch pipe 82 is provided with a valve 821. The second stage liquid outlet 41 of the coagulation sedimentation tank 4 is finally connected to the drain pipe 8. The drain pipe 8 is connected to the insolubilization tank 3 by a branch pipe 82. The pipe 433 is connected to the branch pipe 82 by the branch pipe 435. A cleaning drain port 71 of the auto sand filter 7 is connected to a branch pipe 82 by a cleaning drain pipe 73.
[0038]
The sentiment processing method of the present invention using this cement apparatus will be described. That is, cement dust from the cement manufacturing apparatus is supplied from the cement dust supply pipe 11 to the cement dust washing tank 1. In the cement dust washing tank 1, this sentiment dust is washed with washing water supplied from the water supply pipe 12 under stirring, contains precipitates of cadmium components, and dissolves second double metal components such as lead components. One-stage slurry is discharged from the cement dust washing tank 1 via the slurry discharge port 13. This first stage slurry is sent to the coagulation sedimentation tank 2 through the slurry transfer pipe 14.
[0039]
In the coagulation sedimentation tank 2, the first stage slurry is separated into the first stage liquid and the first stage concentrate under gentle stirring. The first stage liquid component is sent to the insolubilization tank 3 through the liquid transfer pipe 23 from the first stage liquid discharge port 21. On the other hand, the first stage concentrate is discharged from the first stage concentrate outlet 22 via the concentrate transfer pipe 24. Further, an acidic substance such as sulfuric acid is added to the first stage liquid from the acidic substance supply pipe 231 and the first stage liquid is adjusted to a predetermined pH within the range of pH 7-9.
[0040]
A sulfiding agent such as sodium hydrogen sulfide supplied from the sulfiding agent supply pipe 31 is added to the first stage liquid component adjusted to a predetermined pH and sent to the insolubilizing tank 3, and mixed by stirring to obtain the first stage liquid. The second double metal component dissolved in the component is insolubilized, and the first-stage liquid component is the second-stage slurry containing the insolubilized second double metal component.
The second stage slurry is added with a polymer flocculant if desired, and is sent from the second stage slurry discharge port 32 to the coagulation sedimentation tank 4 through the slurry transfer pipe 33.
[0041]
In the coagulation sedimentation tank 4, the second stage slurry is separated into the second stage liquid and the second stage concentrate under gentle stirring. The second stage liquid component is discharged from the second stage liquid discharge port 41 by the liquid transfer pipe 43. On the other hand, the second stage concentrate is discharged from the second stage concentrate discharge port 42 via the pump 441 by the concentrate transfer pipe 44.
[0042]
The second stage concentrate discharged by the concentrate transfer pipe 44 and the first stage concentrate discharged by the concentrate transfer pipe 24 are passed through the pump 51 and sent to the filter 6 by the pipe 5. Mixed with each other to make a mixed concentrate. The mixed concentrate is sent to the filter 6 where it is separated into a liquid and a mixed solid. In the filter 6, the mixed solid is washed with water supplied from the washing water supply pipe 65 and desalted as desired.
[0043]
The liquid separated by the filter 6 is discharged from the liquid discharge port 61 through the liquid transfer pipe 63, and further sent through the valve 6311 to the liquid transfer pipe 23 through the branch pipe 631. In addition, when the liquid discharged by the liquid transfer pipe 63 satisfies various regulation values, the waste water is discharged from the drain pipe 8 connected to the branch pipe 632 by sequentially passing the liquid through the valve 6321 and the valve 6322. Can be released as
Further, the mixed solid separated by the filter 6 is washed with water supplied from the washing water supply pipe 65 and then discharged from the solid discharge outlet 62 if desired, and the entire amount thereof is conveyed by the conveyor 64 to the cement production apparatus. Sent to. The washing waste water after washing the mixed solids is supplied to the cement dust washing tank 1 from the drain port 66 via the liquid transfer means 661.
[0044]
The second stage liquid is passed through the liquid transfer pipe 43, the storage tank 431, the pump 432, the pipe 433, the valve 4331 and the auto sand filter 7 in order, and the filtered water that satisfies various regulatory values is the filtered water outlet. 72, discharged from the drain pipe 8 via the valve 81 as waste water. Further, this filtered water can be returned to the insolubilizing tank 3 through the branch pipe 82 via the valve 821. The washing waste water containing a small amount of solid matter in the auto sand filter 7 is discharged from the washing drain port 71 of the auto sand filter 7 and is returned to the insolubilization tank 3 through the valve 731 through the washing drain pipe 73 and the branch pipe 82. Further, the second-stage liquid component sent through the pipe 433 is sent through the valve 4351 to the branch pipe 82 without passing through the auto sand filter 7, and finally returned to the insolubilization tank 3. You can also. Further, when the second stage liquid component satisfies various regulation values, the branch pipe 434 and the valve 6322 in which the valve 4341 is interposed between the second stage liquid discharged from the pump 432 are provided. It is also possible to pass through the branch pipe 632 intervening in order and directly discharge it from the drain pipe 8 as waste water.
[0045]
Example 2
10 parts by weight of cement dust was washed with water to obtain 110 parts by weight of first stage slurry.
This first-stage slurry was separated into 91 parts by weight of the first-stage liquid having a pH of 13.0 and 19 parts by weight of the first-stage concentrate by a sedimentation coagulation tank. The first stage concentrate was a slurry with high solids concentration and low fluidity. The mixture of the first stage liquid and the total amount of 11 parts by weight of the liquid separated from the mixed concentrate was adjusted to pH 8.8 with sulfuric acid, and 4 parts by weight of 5% aqueous sodium hydrosulfide solution was added. 106 parts by weight of step slurry was obtained. The amount of sulfuric acid used here was 0.43 parts by weight.
[0046]
The whole amount of the second stage slurry was separated into 105 parts by weight of the second stage liquid and 1 part by weight of the second stage concentrate using a sedimentation coagulation tank. The pH of the second stage liquid was 8.53. The second stage concentrate was a slurry having a low solids concentration and a relatively high fluidity. The total amount of the first-stage concentrate and the total amount of the second-stage concentrate are mixed to form a mixed concentrate. The mixed concentrate is separated into a liquid and a mixed solid by a filter. Was washed with water to obtain 22 parts by weight of a liquid and 8.3 parts by weight of a solid.
The cement dust, the first stage liquid, the first stage concentrate, the second stage liquid, the second stage concentrate, the liquid from the mixed concentrate, and the solid after washing and desalting the mixed solid The composition is shown in Table 1.
[0047]
[Table 1]

[0048]
As shown in Table 1, the second-stage liquid component satisfies various regulatory values and can be discharged as waste water as it is.
[0049]
Comparative Example 1
The second-stage concentrate obtained in Example 1 was subjected to solid-liquid separation using the filter used for the solid-liquid separation of the mixed concentrate in Example 1, but contained in the second-stage concentrate. Solid-liquid separation was difficult due to the nature of the solid content.
Furthermore, solid-liquid separation of the second-stage concentrate was attempted using various solid-liquid separation means other than the filter. However, it was difficult to separate the solid-liquid separation.
[0050]
【The invention's effect】
From the slurry containing the second double metal component such as the lead component insolubilized according to the present invention, the second double metal component such as the insolubilized lead component can be easily separated only by ordinary solid-liquid separation means, and various Since only the wastewater that satisfies the regulation value is discharged, there is no danger of polluting the environment.
[Brief description of the drawings]
FIG. 1 is a flow sheet of a typical example of a cement dust treatment apparatus of the present invention.
[Explanation of symbols]
1 Cement dust washing tank
11 Cement dust supply pipe
12 Water supply pipe
13 First stage slurry outlet
14 Slurry transfer pipe
15 Stirrer
2 Coagulation sedimentation tank
21 First stage liquid outlet
22 First stage concentrate outlet
23 Liquid transfer pipe
231 Acidic substance supply pipe
24 Concentrate transfer tube
25 Mud rake
3 Insolubilization tank
31 Sulfiding agent supply pipe
32 Second stage slurry outlet
33 Slurry transfer pipe
34 Stirrer
4 Coagulation sedimentation tank
41 Second stage liquid outlet
42 Second stage concentrate outlet
43 Liquid transfer pipe
431 storage tank
432 pump
433 tubes
4331 valve
434 Branch pipe
4341 Valve
435 branch pipe
4351 valve
44 Concentrate transfer tube
441 pump
45 Mud rake
5 tubes
51 pump
6 Filter
61 Liquid outlet
62 Solid matter outlet
63 Liquid transfer pipe
631 Branch pipe
6311 valve
632 Branch pipe
6321 valves
6322 Valve
64 conveyor
65 Washing water supply pipe
66 Drain port
661 Liquid transfer pipe
7 Auto sand filter
71 Cleaning drain
72 Filtrated water outlet
73 Washing drain
731 valve
8 Drain pipe
81 valve
82 branch pipe
821 Valve
M motor

Claims (4)

The slurry obtained by washing the cement dust with water is subjected to solid-liquid separation, the liquid component separated by the solid-liquid separation is adjusted to pH 7-9, and a sulfidizing agent is added to the pH-adjusted liquid component. It was obtained by insolubilizing the heavy metal component dissolved in the liquid to form a solid and forming the liquid into a slurry, and washing the concentrate from which the liquid was separated and the cement dust with water. A method for treating cement dust, comprising mixing a concentrate separated from a slurry and separating the mixture into solid and liquid. The method for treating cement dust according to claim 1, wherein the heavy metal component to be insolubilized is a lead component. The first stage solid-liquid separation means for slurry from the cement dust washing tank, the pH of the liquid from the first stage solid-liquid separation means is adjusted to 7-9, and mixed with a sulfurizing agent, An insolubilization tank for insolubilizing heavy metal components dissolved in the liquid component and a second stage solid-liquid separation means for slurry from the insolubilization tank are successively connected, and the concentrate is transferred to the first stage solid-liquid separation means. A cement dust treatment apparatus characterized in that the means and the concentrate transfer means of the second-stage solid-liquid separation means are combined to form an integration means, and the integration means is connected to the solid-liquid separation means. 4. The cement dust treatment apparatus according to claim 3, wherein the heavy metal component to be insolubilized in the insolubilization tank is a lead component.

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