JP2009196860A - Method of treating dust containing lead component, potassium component and chlorine component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of treating dust such as incineration main ash, by which a lead component contained in waste gas dust such as chlorine by-pass dust produced with the use of the dust as a clinker raw material is simply and inexpensively recovered with high recovery rate. <P>SOLUTION: The method of treating the dust includes a step (A) of: supplying the clinker raw material containing the dust (for example, the incineration main dust) containing the lead component, the potassium component, and the chlorine component to a cement kiln to fire the clinker; a step (B) of: collecting the chlorine by-pass dust from the waste gas of the cement kiln; and a step (C) of: washing the chlorine by-pass dust with water to obtain a filtrate containing the lead component. In the step (A), the content of potassium in the clinker raw material in the position of a bottom cyclone which is the lowermost stage in a plurality of cyclones constituting a preheater is adjusted to ≤2.5 mass% expressed in terms of oxide. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for treating dust (for example, incinerated main ash, incinerated fly ash, molten fly ash, and chlorine bypass dust) containing a lead component, a potassium component, and a chlorine component.

In a cement kiln that uses dust such as incineration ash from household waste as part of the raw material, exhaust gas with a high chlorine content is generated.
A portion of this exhaust gas can be treated by chlorine bypass technology. Specifically, after extracting part of the exhaust gas from the cement kiln, the coarse powder (solid content with low chlorine content) in the extracted high-temperature exhaust gas is collected with a cyclone and returned to the cement kiln as a cement raw material. On the other hand, fine powder (solids with high chlorine content; hereinafter referred to as chlorine bypass dust) generated by cooling the exhaust gas that has passed through the cyclone is collected by a dust collector such as a bag filter to remove the chlorine component. It is. The collected chlorine bypass dust contains a calcium component, a lead component, a chlorine component, and the like. If the lead component, the chlorine component, etc. are removed, the chlorine bypass dust can be returned to the cement kiln as a clinker raw material containing the calcium component.

Examples of methods for removing lead, chlorine, etc. from fine powders containing calcium, lead, chlorine, etc. include (A) waste containing each component of lead, calcium, and chlorine. A slurrying step of mixing with slurrying water to form a slurry; (B) a classification step of classifying the slurry into coarse and fine particles; and (C) an alkaline agent such as caustic soda in the fine particles. A lead elution step for obtaining a solid solution containing calcium hydroxide and a filtrate containing lead and chlorine, and (D) a sulfiding agent in the filtrate containing lead and chlorine. In order to use lead sulfide as a solid content and a filtrate containing a chlorine content, and (E) the filtrate containing the chlorine content as the slurry water. Including a filtrate returning step of returning to the slurrying step (A) Method of processing waste and said bets have been proposed (Patent Literature 1). Since this processing method includes the step (B) (classification step), it has an advantage that the amount of the alkaline agent used in the step (C) can be reduced.
JP 2003-236497 A

In the technique described in the above-mentioned document, in order to reduce the amount of alkali agent used, etc., waste and water for slurrying are mixed to form a slurry, which is then divided into coarse and fine particles. Classification is performed, and an alkali agent is added only to the fine particles.
Here, the reason for adding the alkaline agent is to increase the liquid pH and increase the elution rate of lead into the liquid.
However, it is more convenient if it is possible to further simplify the process and omit the addition of a chemical such as an alkali agent when obtaining a lead elution rate of a predetermined value or more.
Therefore, the present invention is a method for treating dust such as incinerated main ash, and can easily remove lead components contained in exhaust gas dust such as chlorine bypass dust generated with the use of the dust as a clinker raw material. Another object of the present invention is to provide a processing method that can be recovered at a low cost and at a high recovery rate.

  As a result of intensive studies to solve the above problems, the present inventor has supplied a clinker raw material comprising dust such as incinerated main ash and a general-purpose clinker raw material (limestone, clay, iron slag, etc.) into the cement kiln. When the clinker is fired, if the potassium content in the total amount of the clinker raw material at the bottom cyclone position is adjusted to a specific value or less, the lead component contained in the dust is exhausted from the cement kiln. Because it is discharged out of the kiln as a mainly water-soluble component in the dust contained in this, simply recovering the dust in the exhaust gas using only water, it is highly recovered as a component in the filtrate after cleaning. The present inventors have found that the lead component can be recovered at a high rate.

That is, the present invention provides the following [1] to [5].
[1] (A) Supplying a clinker raw material containing dust containing a lead component, a potassium component and a chlorine component to a cement kiln, and firing the clinker; and (B) exhaust gas from the exhaust gas of the cement kiln. An exhaust gas dust collecting step for collecting dust, and (C) a water washing step for washing the exhaust gas dust to obtain a filtrate containing a lead component, and in step (A), the clinker at the position of the bottom cyclone. The processing method of the dust containing the lead component, potassium component, and chlorine component characterized by adjusting the content rate of potassium in a raw material to 2.5 mass% or less in conversion of an oxide.
[2] The method for treating dust containing a lead component, a potassium component and a chlorine component as described in [1] above, wherein only water is used as a means for eluting lead into the liquid in step (C).
[3] In the step (A), as a part of the clinker raw material, the lead component, the potassium component and the component according to the above [1] or [2], wherein a substance substantially free of a potassium component and containing a chlorine component is used. A method for treating dust containing a chlorine component.
[4] The method for treating dust containing the lead component, potassium component and chlorine component according to any one of [1] to [3], wherein the exhaust gas dust in the step (B) is chlorine bypass dust.
[5] After the step (C), the method includes (D) a lead recovery step of adding a sulfurizing agent to the filtrate containing the lead component and then solid-liquid separation to obtain a solid content containing lead sulfide. The processing method of the dust containing the lead component, potassium component, and chlorine component in any one of [1]-[4].

According to the treatment method of the present invention, the potassium content in the clinker raw material at the position of the bottom cyclone in the lowermost stage of the preheater is adjusted to a specific value or less, so that the water content in the lead component contained in the exhaust gas dust is reduced. As a result, it is possible to elute most of the lead components into the liquid by simply cleaning the exhaust gas dust with water without using an alkali agent such as sodium hydroxide. And lead can be recovered at a high recovery rate.
According to the treatment method of the present invention, the lead component can be recovered from the exhaust gas dust at a high recovery rate only by washing with water without performing alkali leaching or classification of the slurry after washing with water. Therefore, it is possible to simplify the processing steps and reduce costs due to non-use of the medicine.

Hereinafter, the processing method of the dust containing the lead component, potassium component, and chlorine component of this invention is demonstrated in detail. FIG. 1 is a flowchart showing an example of the processing method of the present invention.
The processing method of the dust containing the lead component of this invention, a potassium component, and a chlorine component supplies the clinker raw material containing the dust containing (A) lead component, a potassium component, and a chlorine component to a cement kiln, A firing step for firing; (B) an exhaust gas dust collecting step for collecting exhaust gas dust from the exhaust gas of the cement kiln; and (C) a water washing step for washing the exhaust gas dust to obtain a filtrate containing a lead component. Including.
Moreover, the processing method of this invention is the lead which obtains solid content containing lead sulfide by solid-liquid separation, after adding a sulfurizing agent to the filtrate containing the lead component obtained in (D) step (C). A recovery step.

[Step (A)]
In this step, the clinker raw material containing dust containing a lead component, a potassium component, and a chlorine component is supplied to the cement kiln, and the clinker is fired.
The dust which is the target of the treatment method of the present invention is dust containing a lead component, a potassium component and a chlorine component. Here, the term “component” such as “lead component” is meant to include compounds, complexes, ions, and the like.
Examples of the dust include incinerated main ash, incinerated fly ash, molten fly ash, and chlorine bypass dust.
The clinker raw material includes dust (for example, incinerated main ash) containing a lead component, a potassium component, and a chlorine component, and other general-purpose clinker raw materials (limestone, clay, iron slag, etc.).
Of these, dust containing lead components and the like is usually charged at a constant charging speed into the lowest cyclone, calciner, cement kiln bottom, and the like.
The general-purpose clinker raw material is a raw material such as ordinary Portland cement, and is supplied from the upper part of the preheater of the cement manufacturing apparatus and led to a cement kiln (rotary kiln) via a plurality of cyclones constituting the preheater.
In the cement kiln, a clinker raw material obtained by mixing dust such as incinerated main ash and other general-purpose clinker raw material is heated at a predetermined temperature, and the granular clinker is fired.

The content of potassium in the clinker raw material is 2.5% by mass or less, preferably 2.2% by mass or less, more preferably 1.9% by mass or less, particularly preferably 1 in terms of oxide at the bottom cyclone position. 0.7 mass% or less.
Here, the “position of the bottom cyclone” refers to the position in the lowermost cyclone among the plurality of cyclones constituting the preheater.
When the potassium content is 2.3% by mass or less, in the later-described step (C), when washed with water only, the total amount of lead components contained in the exhaust gas dust is in the liquid. The mass ratio (lead recovery rate) of the lead component to be eluted is 40% by mass or more. When the potassium content is 2.2% by mass or less, the lead recovery rate is 50% by mass or more. When the potassium content is 1.9% by mass or less, the lead recovery rate is 60% by mass or more. When the potassium content is 1.7% by mass or less, the lead recovery rate is 65% by mass or more.
The lower limit of the potassium content is preferably 1.0% by mass or more, more preferably 1.2% by mass or more, in terms of oxide. If the value is less than 1.0% by mass, not only the increase in the recovery rate of lead will reach a peak, but also the mass ratio of dust such as incineration main ash in the total amount of clinker raw material will become small, and the amount of dust such as incineration main ash will decrease. It becomes difficult to promote treatment (promote reuse of waste).

  As a preferable means for reducing the potassium content in the clinker raw material, a substance containing substantially no potassium component and containing a chlorine component (particularly, it becomes ash by combustion by heating and constitutes a component in exhaust gas dust) Combustible substances). Examples of the substance include waste plastic containing chlorine (for example, a pulverized product of vinyl chloride resin). If such a substance is used as a part of the clinker raw material, the total amount of the clinker raw material can be increased. Therefore, the content of potassium in the clinker raw material can be reduced without reducing the input amount of dust containing lead components. Can be reduced.

From the viewpoint of promoting the volatilization of the lead component, the chlorine content in the clinker raw material is preferably 0.10% by mass or more, more preferably 0.13% by mass or more, and particularly preferably 0.16% by mass or more. .
The upper limit of the chlorine content in the clinker raw material is preferably 0.20% by mass, more preferably 0.18% by mass, from the viewpoint of keeping the content of chlorine in the clinker to be fired low.

[Step (B)]
This step is a step of collecting exhaust gas dust from the exhaust gas of the cement kiln.
In the present specification, the “exhaust gas dust” may be the total amount of dust in the exhaust gas of the cement kiln, or may be a part of the dust in the exhaust gas of the cement kiln.
As a preferable example of this process, after extracting a part of the exhaust gas from the cement kiln, the coarse powder (solid content with low chlorine content) in the extracted high-temperature exhaust gas is collected with a cyclone, and cement is used as a cement raw material. While returning to the kiln, the fine powder (solid content with a large chlorine content; chlorine bypass dust) generated by cooling the exhaust gas that has passed through the cyclone is collected as exhaust gas dust by a dust collector such as a bag filter.

[Step (C)]
This step is a step in which exhaust gas dust is washed with water to obtain a filtrate containing a lead component.
Washing with water can be performed using only water.
In the present invention, as a means for eluting the lead component from the exhaust gas dust into the liquid, the above lead recovery rate can be obtained even when only water is used without using an alkali agent or the like. it can. Therefore, it is possible to avoid an increase in processing time and cost due to the use of a chemical agent such as an alkaline agent and the combined use of additional steps such as classification.
At the time of washing with water, the amount of exhaust gas dust per liter of water is preferably 50 g or more, more preferably 60 g or more, and particularly preferably 70 g or more. If the amount is less than 50 g, the amount of water used per unit mass of the exhaust gas dust is large, so that not only the treatment cost increases but also the wastewater treatment burden increases.
The upper limit of the amount of exhaust gas dust per liter of water is preferably 400 g or less, more preferably 250 g or less, and particularly preferably 150 g or less. If the amount exceeds 400 g, water can be saved, but the amount of exhaust gas dust per unit water amount is too large, making it difficult to sufficiently elute lead into the liquid and reducing the lead recovery rate. there is a possibility.

As an example of the water washing method in this process, after mixing exhaust gas dust and water using the liquid tank etc. which have a stirring blade, the method of carrying out solid-liquid separation is mentioned.
The water used in this step is usually new water (industrial water or tap water) supplied from outside the system.
Examples of the solid-liquid separation means include an endless belt filter in which a vacuum suction device for sucking a liquid component of a solid-liquid separation target is disposed below the filter. Above this endless belt filter, a water spraying device for washing the solid content after solid-liquid separation may be disposed.
The solid content obtained by solid-liquid separation usually contains calcium hydroxide as a main component and does not contain a chlorine component or a heavy metal component, so that it can be used as a clinker raw material.
A liquid component (filtrate containing a lead component) obtained by solid-liquid separation contains a water-soluble lead component eluted in the solution and components such as sodium and potassium components.

[Step (D)]
This step is a step of obtaining a solid component containing lead sulfide and a liquid component by adding a sulfiding agent to the filtrate containing the lead component, followed by solid-liquid separation.
Examples of the sulfurizing agent include sodium hydrosulfide (NaSH) and sodium sulfide (Na ₂ S). The addition amount of the sulfiding agent is desirably the same as or slightly larger than the amount necessary for sulfiding all the lead components in the liquid.
By adding a sulfurizing agent, the lead component in the liquid becomes a hardly soluble lead sulfide (for example, lead sulfide), and a slurry is generated.
In this step, pH adjustment is not necessary. This is because there is no possibility that the quality of lead sulfide deteriorates due to the presence of hydroxide or the like in the liquid, and the presence of hydroxide in the solid in a strong alkaline atmosphere. .
Examples of the solid-liquid separation means include a filter press.
The solid content obtained by solid-liquid separation contains lead sulfide and can be used as a non-ferrous refining raw material suitable for Yamamoto reduction.
The liquid component obtained by solid-liquid separation contains a potassium component, a sodium component, a chlorine component, and the like. This liquid component is discharged out of the system after passing through the waste water treatment step.

Hereinafter, the present invention will be described by way of examples. In the following text, “%” is based on mass unless otherwise specified.
[Example 1]
As a clinker raw material, a mixture of 100 parts by mass of ordinary clinker raw material for ordinary Portland cement, 10 parts by mass of incinerated main ash, and 2 parts by mass of a pulverized polyvinyl chloride waste plastic was used.
The composition of incinerated main ash is as follows: calcium 17.3% by mass, sodium 2.4% by mass, potassium 1.2% by mass, lead 0.3% by mass, chlorine 0.9% by mass. The mass ratio in terms of oxide.
The mass proportion of potassium in the clinker raw material at the position of the bottom cyclone was 1.62% by mass in terms of oxide.
Clinker raw material was put into a cement kiln to obtain clinker, while a part of the exhaust gas was extracted to obtain chlorine bypass dust.
This chlorine bypass dust is composed of 30.6% calcium, 23.5% potassium, 2.7% sodium, 13.6% sulfur, 5.5% lead, 15.1% chlorine (excluding lead and chlorine, oxides It is a value in terms of conversion. The unit is based on mass.).

After putting 10 liters of water (liquid temperature: 25 ° C.) into a liquid tank having a stirring blade, 1 kg of chlorine bypass dust was added and stirred for 30 minutes.
The obtained slurry is filtered with an endless belt filter equipped with a decompression device, and the solid content (containing calcium hydroxide, etc.) and liquid content (containing lead component, sodium component, potassium component, chlorine component, etc.) Got.
After storing the obtained liquid in a liquid tank having a stirring blade, 16 g of sodium hydrosulfide (NaSH) was added to this liquid and stirred for 20 minutes to obtain a slurry.
The obtained slurry was subjected to solid-liquid separation with a filter press to obtain a solid content (containing a lead sulfide) and a liquid content (containing a potassium component, a sodium component, a chlorine component, etc.).
The mass of the obtained solid (dry state) was 498 g. Moreover, the content rate of lead in solid content was 3.1 mass%.
The recovery rate of lead from chlorine bypass dust was calculated to be 72.1% by mass.

[Example 2]
As a clinker raw material, a mixture of 100 parts by mass of ordinary clinker raw material for ordinary Portland cement, 10 parts by mass of incinerated main ash, and 2 parts by mass of a pulverized polyvinyl chloride waste plastic was used.
The composition of incinerated main ash is as follows: calcium 17.3% by mass, sodium 2.4% by mass, potassium 1.2% by mass, lead 0.3% by mass, chlorine 0.9% by mass. The mass ratio in terms of oxide.
The mass ratio of potassium in the clinker raw material at the position of the bottom cyclone was 1.63 mass% in terms of oxide.
Clinker raw material was put into a cement kiln to obtain clinker, while a part of the exhaust gas was extracted to obtain chlorine bypass dust.
This chlorine bypass dust is composed of 36.6% calcium, 17.9% potassium, 2.0% sodium, 16.5% sulfur, 5.3% lead, 10.1% chlorine (excluding lead and chlorine, oxides) It is a value in terms of conversion. The unit is based on mass.).

After putting 10 liters of water (liquid temperature: 25 ° C.) into a liquid tank having a stirring blade, 1 kg of chlorine bypass dust was added and stirred for 30 minutes.
The obtained slurry is filtered with an endless belt filter equipped with a decompression device, and the solid content (containing calcium hydroxide, etc.) and liquid content (containing lead component, sodium component, potassium component, chlorine component, etc.) Got.
After storing the obtained liquid in a liquid tank having a stirring blade, 16 g of sodium hydrosulfide (NaSH) was added to this liquid and stirred for 20 minutes to obtain a slurry.
The obtained slurry was subjected to solid-liquid separation with a filter press to obtain a solid content (containing a lead sulfide) and a liquid content (containing a potassium component, a sodium component, a chlorine component, etc.).
The mass (dry state) of the obtained solid content was 619 g. Moreover, the content rate of lead in solid content was 2.8 mass%.
The recovery rate of lead from chlorine bypass dust was calculated to be 67.8% by mass.

[Example 3]
As a clinker raw material, a mixture of 100 parts by mass of a normal clinker raw material for ordinary Portland cement, 10 parts by mass of incinerated main ash, and 3 parts by mass of a pulverized polyvinyl chloride waste plastic was used.
The component composition of the incinerated main ash is 20.1% by mass of calcium, 2.0% by mass of sodium, 0.9% by mass of potassium, 0.2% by mass of lead, and 1.0% by mass of chlorine. The mass ratio in terms of oxide.
The mass ratio of potassium in the clinker raw material at the position of the bottom cyclone was 1.65% by mass in terms of oxide.
Clinker raw material was put into a cement kiln to obtain clinker, while a part of the exhaust gas was extracted to obtain chlorine bypass dust.
This chlorine bypass dust is composed of 24.4% calcium, 29.4% potassium, 3.3% sodium, 11.1% sulfur, 4.8% lead, 20.1% chlorine (excluding lead and chlorine, oxides It is a value in terms of conversion. The unit is based on mass.).

After putting 10 liters of water (liquid temperature: 25 ° C.) into a liquid tank having a stirring blade, 1 kg of chlorine bypass dust was added and stirred for 30 minutes.
The obtained slurry is filtered with an endless belt filter equipped with a decompression device, and the solid content (containing calcium hydroxide, etc.) and liquid content (containing lead component, sodium component, potassium component, chlorine component, etc.) Got.
After storing the obtained liquid in a liquid tank having a stirring blade, 16 g of sodium hydrosulfide (NaSH) was added to this liquid and stirred for 20 minutes to obtain a slurry.
The obtained slurry was subjected to solid-liquid separation with a filter press to obtain a solid content (containing a lead sulfide) and a liquid content (containing a potassium component, a sodium component, a chlorine component, etc.).
The mass of the obtained solid (dry state) was 419 g. Moreover, the content rate of lead in solid content was 3.4 mass%.
The recovery rate of lead from chlorine bypass dust was calculated to be 70.1% by mass.

[Example 4]
As a clinker raw material, a mixture of 100 parts by mass of a normal clinker raw material for ordinary Portland cement, 10 parts by mass of incinerated main ash, and 3 parts by mass of a pulverized polyvinyl chloride waste plastic was used.
The composition of the incinerated main ash is as follows: calcium 19.1% by weight, sodium 1.9% by weight, potassium 1.0% by weight, lead 0.3% by weight, chlorine 0.8% by weight (however, components other than chlorine are The mass ratio in terms of oxide.
The mass ratio of potassium in the clinker raw material at the position of the bottom cyclone was 1.77% by mass in terms of oxide.
Clinker raw material was put into a cement kiln to obtain clinker, while a part of the exhaust gas was extracted to obtain chlorine bypass dust.
This chlorine bypass dust is composed of 22.2% calcium, 32.1% potassium, 4.0% sodium, 9.2% sulfur, 3.8% lead, 22.8% chlorine (excluding lead and chlorine, oxides It is a value in terms of conversion. The unit is based on mass.).

After putting 10 liters of water (liquid temperature: 25 ° C.) into a liquid tank having a stirring blade, 1 kg of chlorine bypass dust was added and stirred for 30 minutes.
The obtained slurry is filtered with an endless belt filter equipped with a decompression device, and the solid content (containing calcium hydroxide, etc.) and liquid content (containing lead component, sodium component, potassium component, chlorine component, etc.) Got.
After storing the obtained liquid in a liquid tank having a stirring blade, 16 g of sodium hydrosulfide (NaSH) was added to this liquid and stirred for 20 minutes to obtain a slurry.
The obtained slurry was subjected to solid-liquid separation with a filter press to obtain a solid content (containing a lead sulfide) and a liquid content (containing a potassium component, a sodium component, a chlorine component, etc.).
The mass of the obtained solid (dry state) was 372 g. Moreover, the content rate of lead in solid content was 3.7 mass%.
The recovery rate of lead from chlorine bypass dust was calculated to be 63.9% by mass.

[Example 5]
As a clinker raw material, a mixture of 100 parts by weight of a normal clinker raw material for ordinary Portland cement and 10 parts by weight of incinerated main ash was used.
The composition of incinerated main ash is as follows: calcium 19.2%, sodium 2.0%, potassium 1.2%, lead 0.3%, chlorine 1.0% (except for chlorine) The mass ratio in terms of oxide.
The mass ratio of potassium in the clinker raw material at the position of the bottom cyclone was 2.10 mass% in terms of oxide.
Clinker raw material was put into a cement kiln to obtain clinker, while a part of the exhaust gas was extracted to obtain chlorine bypass dust.
This chlorine bypass dust is composed of 48.5% calcium, 11.1% potassium, 1.4% sodium, 13.2% sulfur, 2.6% lead, 8.0% chlorine (excluding lead and chlorine, oxides It is a value in terms of conversion. The unit is based on mass.).

After putting 10 liters of water (liquid temperature: 25 ° C.) into a liquid tank having a stirring blade, 1 kg of chlorine bypass dust was added and stirred for 30 minutes.
The obtained slurry is filtered with an endless belt filter equipped with a decompression device, and the solid content (containing calcium hydroxide, etc.) and liquid content (containing lead component, sodium component, potassium component, chlorine component, etc.) Got.
After storing the obtained liquid in a liquid tank having a stirring blade, 16 g of sodium hydrosulfide (NaSH) was added to this liquid and stirred for 20 minutes to obtain a slurry.
The obtained slurry was subjected to solid-liquid separation with a filter press to obtain a solid content (containing a lead sulfide) and a liquid content (containing a potassium component, a sodium component, a chlorine component, etc.).
The mass of the obtained solid (dry state) was 741 g. Moreover, the content rate of lead in solid content was 1.4 mass%.
The recovery rate of lead from chlorine bypass dust was calculated to be 58.8% by mass.

[Example 6]
As a clinker raw material, a mixture of 100 parts by weight of a normal clinker raw material for ordinary Portland cement and 10 parts by weight of incinerated main ash was used.
The composition of the incinerated main ash is 21.1% by weight calcium, 1.9% by weight sodium, 1.4% by weight potassium, 0.2% by weight lead, 0.9% by weight chlorine (however, components other than chlorine are The mass ratio in terms of oxide.
The mass ratio of potassium in the clinker raw material at the position of the bottom cyclone was 2.15% by mass in terms of oxide.
Clinker raw material was put into a cement kiln to obtain clinker, while a part of the exhaust gas was extracted to obtain chlorine bypass dust.
This chlorine bypass dust is composed of 31.5% calcium, 24.3% potassium, 3.1% sodium, 11.8% sulfur, 4.8% lead, 16.9% chlorine (excluding lead and chlorine, oxides It is a value in terms of conversion. The unit is based on mass.).

After putting 10 liters of water (liquid temperature: 25 ° C.) into a liquid tank having a stirring blade, 1 kg of chlorine bypass dust was added and stirred for 30 minutes.
The obtained slurry is filtered with an endless belt filter equipped with a decompression device, and the solid content (containing calcium hydroxide, etc.) and liquid content (containing lead component, sodium component, potassium component, chlorine component, etc.) Got.
After storing the obtained liquid in a liquid tank having a stirring blade, 16 g of sodium hydrosulfide (NaSH) was added to this liquid and stirred for 20 minutes to obtain a slurry.
The obtained slurry was subjected to solid-liquid separation with a filter press to obtain a solid content (containing a lead sulfide) and a liquid content (containing a potassium component, a sodium component, a chlorine component, etc.).
The mass (dry state) of the obtained solid content was 503 g. Moreover, the content rate of lead sulfide in solid content was 4.5 mass%.
The recovery rate of lead from chlorine bypass dust was calculated to be 53.4% by mass.

[Example 7]
As a clinker raw material, a mixture of 100 parts by weight of a normal clinker raw material for ordinary Portland cement and 10 parts by weight of incinerated main ash was used.
The component composition of the incinerated main ash is 22.0% by mass of calcium, 1.7% by mass of sodium, 2.4% by mass of potassium, 0.2% by mass of lead, and 1.4% by mass of chlorine. The mass ratio in terms of oxide.
The mass ratio of potassium in the clinker raw material at the position of the bottom cyclone was 2.25 mass% in terms of oxide.
Clinker raw material was put into a cement kiln to obtain clinker, while a part of the exhaust gas was extracted to obtain chlorine bypass dust.
This chlorine bypass dust is composed of 12.6% calcium, 37.4% potassium, 3.3% sodium, 10.6% sulfur, 6.5% lead, 25.4% chlorine (excluding lead and chlorine, oxides It is a value in terms of conversion. The unit is based on mass.).

After putting 10 liters of water (liquid temperature: 25 ° C.) into a liquid tank having a stirring blade, 1 kg of chlorine bypass dust was added and stirred for 30 minutes.
The obtained slurry is filtered with an endless belt filter equipped with a decompression device, and the solid content (containing calcium hydroxide, etc.) and liquid content (containing lead component, sodium component, potassium component, chlorine component, etc.) Got.
After storing the obtained liquid in a liquid tank having a stirring blade, 16 g of sodium hydrosulfide (NaSH) was added to this liquid and stirred for 20 minutes to obtain a slurry.
The obtained slurry was subjected to solid-liquid separation with a filter press to obtain a solid content (containing a lead sulfide) and a liquid content (containing a potassium component, a sodium component, a chlorine component, etc.).
The mass (dry state) of the obtained solid was 252 g. Moreover, the content rate of lead in solid content was 13.1 mass%.
The recovery rate of lead from chlorine bypass dust was calculated to be 49.1% by mass.

[Example 8]
As a clinker raw material, a mixture of 100 parts by mass of a normal clinker raw material for ordinary Portland cement and 7 parts by mass of incinerated main ash was used.
The component composition of the incinerated main ash is 22.0% by mass of calcium, 1.7% by mass of sodium, 2.4% by mass of potassium, 0.2% by mass of lead, and 1.4% by mass of chlorine. The mass ratio in terms of oxide.
The mass ratio of potassium in the clinker raw material at the position of the bottom cyclone was 2.27 mass% in terms of oxide.
Clinker raw material was put into a cement kiln to obtain clinker, while a part of the exhaust gas was extracted to obtain chlorine bypass dust.
This chlorine bypass dust is composed of 22.3% calcium, 26.0% potassium, 3.0% sodium, 17.7% sulfur, 8.0% lead, 16.7% chlorine (excluding lead and chlorine, oxides). It is a value in terms of conversion. The unit is based on mass.).

After putting 10 liters of water (liquid temperature: 25 ° C.) into a liquid tank having a stirring blade, 1 kg of chlorine bypass dust was added and stirred for 30 minutes.
The obtained slurry is filtered with an endless belt filter equipped with a decompression device, and the solid content (containing calcium hydroxide, etc.) and liquid content (containing lead component, sodium component, potassium component, chlorine component, etc.) Got.
After storing the obtained liquid in a liquid tank having a stirring blade, 16 g of sodium hydrosulfide (NaSH) was added to this liquid and stirred for 20 minutes to obtain a slurry.
The obtained slurry was subjected to solid-liquid separation with a filter press to obtain a solid content (containing a lead sulfide) and a liquid content (containing a potassium component, a sodium component, a chlorine component, etc.).
The mass of the obtained solid (dry state) was 418 g. Moreover, the content rate of lead in solid content was 10.6 mass%.
The recovery rate of lead from chlorine bypass dust was calculated to be 44.6% by mass.
The results of Examples 1 to 8 are summarized in Table 1.
From Table 1, it can be seen that according to the treatment method of the present invention, the lead component can be recovered from the chlorine bypass dust at a high recovery rate (Examples 1 to 8).

It is a flowchart which shows an example of the processing method of the dust containing the lead component, potassium component, and chlorine component of this invention.

Claims (5)

(A) A clinker raw material containing dust containing a lead component, a potassium component, and a chlorine component is supplied to the cement kiln, and the clinker is fired. (B) The exhaust gas dust is captured from the exhaust gas of the cement kiln. An exhaust gas dust collecting step for collecting, and (C) a water washing step for washing the exhaust gas dust to obtain a filtrate containing a lead component, and in step (A), in the clinker raw material at the position of the bottom cyclone A method for treating dust containing a lead component, a potassium component and a chlorine component, wherein the potassium content is adjusted to 2.5% by mass or less in terms of oxide.   The processing method of the dust containing the lead component, potassium component, and chlorine component of Claim 1 which uses only water as a means for eluting lead in a liquid in a process (C).   3. A dust containing a lead component, a potassium component and a chlorine component according to claim 1 or 2, wherein a substance containing substantially no potassium component and containing a chlorine component is used as part of the clinker raw material in step (A). Processing method.   The said waste gas dust in a process (B) is chlorine bypass dust, The processing method of the dust containing the lead component, potassium component, and chlorine component of any one of Claims 1-3.   The step (C) includes a step (D) of recovering a lead containing the lead component, followed by solid-liquid separation to obtain a solid content containing lead sulfide, after the step (C). The processing method of the dust containing the lead component of any one of 4, a potassium component, and a chlorine component.

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