JP6274875B2 - Method and apparatus for converting waste incineration ash into cement raw material - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a method and apparatus for recycling waste incineration ash (main ash) generated when municipal waste or the like is incinerated as a cement raw material.

  Most of the incineration ash (hereinafter referred to as “waste incineration ash”) generated when incinerating municipal waste has been landfilled at the final disposal site, but in view of the danger of depletion of the final disposal site, In recent years, it has been effectively used as a cement raw material.

  Waste incineration ash contains about 1.2% of chlorine on average, and this chlorine prevents deterioration of cement quality and stable operation of cement manufacturing equipment. There is a need.

  Therefore, for example, in Patent Document 1, a crushing step in which water is added to incineration ash to crush particles in the incineration ash to agitate the incineration ash slurry, and the incineration ash slurry is passed through a screening sieve. An incineration ash having a foreign matter removal process for removing excessive solids, a dehydration process for dewatering the incinerated ash slurry that has passed through the screening sieve with a sieve for draining, and a rinse washing process for rinsing and washing the incinerated ash that has passed through the dehydration process. A cleaning method and the like are described.

  In addition to soluble salts, there are also sparingly soluble Friedel's salts in the main ash, so after pulverizing the entire amount of the main ash, the Friedel's salt is decomposed with acid and then effectively used as a raw material for cement. (See Patent Document 2).

JP 2012-166170 A JP 2006-326462 A

  However, in the cement raw material conversion method as described in Patent Document 1, a large amount of water is consumed in the crushing process and the rinsing and cleaning process, so that the operation cost and the equipment cost increase.

  In addition, as described in Patent Document 2, in order to pulverize the total amount of main ash received and treat with acid, the scale of the pulverization equipment and the like increase in size and energy cost, and the operating cost and equipment cost are reduced. There was a problem of soaring.

  Then, this invention is made | formed in view of the problem in the said prior art, Comprising: It aims at making waste incineration ash into a cement raw material, suppressing installation cost and operation cost low.

In order to achieve the above object, the present invention adds 0.1 to 2.0 times the amount of water with respect to the waste incineration ash and stirs while sludge to make a slurry. The slurry containing coarse particles and the slurry containing fine particles are classified while being sprinkled, and the slurry containing the classified fine particles is further classified while being sprinkled into the slurry containing coarse particles and the slurry containing fine particles. The acidic gas or acid is added to the slurry containing the fine particles obtained by classification, and the slurry containing the fine particles after the addition of the acidic gas or acid is solid-liquid separated, and the cake obtained by the solid-liquid separation is cemented It is used as a raw material.

According to the cement raw material production method according to the present invention, the whole amount of the refuse incineration ash is pulverized, or without pulverization or surface grinding, after stirring and slurring while thawing, containing chlorine content Decomposes poorly soluble Friedel's salt in a slurry containing fine particles, so the amount of fine particles does not increase, the amount of washing water can be reduced, and waste incineration ash is cemented while keeping facility and operating costs low. Can be used as a raw material. In addition, by performing the classification process while sprinkling water in two stages, the amount of water required for the process can be halved, and the slurry containing fine particles obtained by the second classification with a high content of chlorine By decomposing the hardly soluble salt, the chlorine content can be further effectively reduced. Furthermore, when slurrying the waste incineration ash, water in an amount of 0.1 to 2.0 times the amount of the waste incineration ash can be used. Can be classified.

  In the cement raw material conversion method, as the acid gas, exhaust gas from a cement kiln or / and exhaust gas from a chlorine bypass facility can be used, and exhaust gas from the cement firing step can be effectively used.

  Furthermore, the maximum particle size of the fine particles obtained by the first or second classification can be adjusted to 1 mm or less, and thereby the hardly soluble salt in the slurry containing the fine particles having a high chlorine content is effective. Can be decomposed.

Furthermore, the present invention is an apparatus for converting waste incineration ash into a cement raw material, which is a slurry prepared by adding 0.1 to 2.0 times the amount of water with respect to the waste incineration ash and stirring while deflocculating. and slurrying device for reduction, the slurry containing coarse particles slurried ash slurry in the slurry apparatus, a first classifying unit for classifying while spraying water and a slurry containing fine particles, classified by the first classification apparatus adding a slurry containing further coarse particles of the slurry, and the second classifying device for classifying while spraying water and a slurry containing fine particles, the acid gas or acid to the slurry containing the classified fine particles in the second classification apparatus containing particulate And a solid-liquid separation device for solid-liquid separation of the slurry containing the fine particles discharged from the reaction tank.

According to the present invention, since the classification process is performed while watering in two stages, the amount of water required for the process can be halved, and the fine particles obtained by the second classification with a high chlorine content can be obtained. By adding an acid gas or an acid to the slurry containing it to decompose the hardly soluble salt, the waste incineration ash can be used as a cement raw material while keeping facility costs and operation costs low.

  As described above, according to the present invention, waste incineration ash can be used as a cement raw material while keeping facility costs and operation costs low.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole block diagram which shows one Embodiment of the cement raw material production apparatus concerning this invention.

  Next, an embodiment of a cement raw material producing apparatus according to the present invention will be described with reference to FIG. In FIG. 1, a broken arrow indicates a liquid flow, an alternate long and short dash arrow indicates a gas flow, and a solid arrow indicates a solid (including slurry) flow.

  FIG. 1 shows an embodiment of a cement raw material production apparatus according to the present invention. This cement raw material production apparatus 1 is a main ash tank 2 for storing received refuse incineration ash (hereinafter referred to as “main ash”) BA. A slurrying device 3 for adding water W or the like to the main ash BA and stirring to make a slurry while removing the slurry, a slurry S2 containing coarse particles from the main ash slurry S1 from the slurrying device 3, and a fine particle A first classifying device 4 for classifying into a slurry containing, a second classifying device 5 for classifying the slurry containing fine particles classified by the first classifying device 4 into a slurry S3 containing coarse particles and a slurry S4 containing fine particles, The wet pulverizer 6 for wet pulverizing the slurry S4 classified by the second classifier 5, the reaction tank 7 for reacting the wet pulverized slurry S5 with the acid gas G, and the acidic gas G is introduced into the reaction tank 7. Acid gas guide A device 4, and a solid-liquid separator 9 and the like to solid-liquid separation of the slurry S6 in the reaction vessel 7.

  The slurrying device 3 is provided to add water to the main ash BA and stir it while thawing to produce the main ash slurry S1.

  The first classifying device 4 is provided to classify the main ash slurry S1 from the slurrying device 3 into a slurry S2 containing coarse particles and a slurry containing fine particles, and the classification point is 2 mm.

  The second classifier 5 is provided to classify the slurry containing fine particles classified by the first classifier 4 into a slurry S3 containing coarse particles and a slurry S4 containing fine particles, and 0.7 mm as a classification point. To do.

  The wet pulverizer 6 is provided to wet pulverize the slurry S4 classified by the second classifier 5.

The acidic gas introduction device 8 is provided to introduce the acidic gas G into the reaction tank 7, and as the acidic gas to be introduced, the exhaust gas of a cement kiln containing a large amount of CO ₂ or the exhaust gas of a chlorine bypass facility containing a large amount of SO ₂ is used. Can be used.

  The reaction tank 7 is provided for reacting the wet-pulverized slurry S5 with the acid gas G, and a batch type or continuous type aeration tank or the like can be used.

  The solid-liquid separation device 9 is provided for solid-liquid separation of the slurry S6 from the reaction tank 7.

  Next, the operation of the cement raw material producing apparatus according to the present invention will be described with reference to the drawings.

  First, in the slurrying apparatus 3, the main ash slurry S1 is generated by adding water W to the main ash BA and stirring the ash while demelting. In the slurrying, water is used in an amount of 0.1 to 2.0 times that of the main ash BA. The reason is that the main ash BA received is agglomerated by moisture, and classification is difficult as it is. In the present invention, since pulverization, pulverization, and surface grinding are not performed, fine particles are not increased, and the amount of washing water can be reduced.

  Next, the main ash slurry S1 from the slurrying apparatus 3 is supplied to the first classifying apparatus 4 and classified into a slurry S2 containing coarse particles having a particle diameter of 2 mm or more and a slurry containing fine particles having a particle diameter of 2 mm or less, and the slurry After draining S2, the cement raw material is charged into the calcining furnace of the cement firing apparatus 10 after draining.

  The slurry containing particles having a particle size of 2 mm or less is supplied to the second classifier 5, and further classified into a slurry S3 containing particles having a particle size of 0.7 mm or more and a slurry S4 containing particles having a particle size of 0.7 mm or less. Then, the slurry S3 is drained, and then charged into the calcining furnace of the cement baking apparatus 10 as a cement raw material.

  The slurry S4 containing particles having a particle size of 0.7 mm or less classified by the second classifier 5 is supplied to the wet pulverizer 6 and wet pulverized. Then, it supplies to the reaction tank 7, makes it react with the acidic gas G from the acidic gas introduction apparatus 8 in the reaction tank 7, and decomposes Friedel's salt contained in the main ash BA. The reason for the slurry S4 containing particles having a particle size of 0.7 mm or less is that the particles having a small particle size contain a large amount of chlorine. Is to increase

In addition, Friedel's salt is 3CaO · Al ₂ O ₃ · CaCl ₂ · 10H ₂ O in chemical formula, and trilime aluminate (3CaO · Al ₂ O ₃ ) is hydrated as described below. It is a salt produced by taking in chloride ions during the reaction.
3CaO.Al ₂ O ₃ + CaCl ₂ + 10H ₂ O → 3CaO.Al ₂ O ₃ .CaCl ₂ .10H ₂ O

When exhaust gas of cement kiln is blown into the slurry as acidic gas G, Friedel's salt can be decomposed as shown in the following formula.
_{3CaO · Al 2 O 3 · CaCl} 2 · 10H 2 O + 3CO 2 → 3CaCO 3 + 2Al (OH) 3 + CaCl 2 + 7H 2 O

Moreover, when the exhaust gas of chlorine bypass equipment is blown into the slurry as the acidic gas G, Friedel's salt can be decomposed as shown in the following formula.
_{3CaO · Al 2 O 3 · CaCl} 2 · 10H 2 O + XSO 4 2- → 3CaO · Al 2 O 3 · 3CaSO 4 · 32H 2 O + YCl -

  At this time, the pH in the reaction vessel 7 is adjusted to 4 to 10.5.

  The slurry S6 that has finished the reaction with the acid gas G is introduced into the solid-liquid separator 9, and is dehydrated while being washed with the cake washing water (new water) W1, or while being washed. The cake C after dehydration is put into a calcining furnace of the cement baking apparatus 10 as a cement raw material. Moreover, the waste water W3 of the solid-liquid separator 9 is discharged after the waste water treatment, and a part of the waste water W2 is returned to the slurrying device 3 for circulation. Further, the filtrate F1 separated by the solid-liquid separation device 9 can be returned to the slurrying device 3 and reused. At this time, it is preferable to determine the circulation amount of the waste water W2 while measuring the electrical conductivity of the filtrate F1 and managing the chlorine concentration of the filtrate F1.

  In the above embodiment, the classification point of the first classification device 4 is 2 mm, and the classification point of the second classification device 5 is 0.7 mm. Classification points can be changed as appropriate. However, the classification point of the second classifier 5 is preferably 1 mm or less in order to effectively remove chlorine.

  Further, by classifying while sprinkling water in the first classifying device 4 and the second classifying device 5, fine particles adhering to the coarse particles can be separated from the coarse particles, or the coarse particles can be washed with water to some extent. In particular, the chlorine content can be reduced, and it is not necessary to separately provide a washing facility for coarse particles. The amount of water spray is adjusted to 1 to 4 times the amount of main ash BA to be treated.

  Further, an acid such as sulfuric acid, nitric acid, acetic acid and formic acid may be added without introducing the acidic gas G into the reaction vessel 7.

Further, not only the acidic gas G and the acid but also an oxidizing gas such as O ₃ can be introduced into the reaction tank 7 to reduce the COD and reduce the load of the waste water treatment at the subsequent stage. Without introducing the oxidizing gas into the reaction tank 7, the tank can be multistaged, and the acidic gas G and the oxidizing gas can be introduced separately.

  Furthermore, although the slurries S2, S3 and the cake C are used as cement raw materials in the calcining furnace of the cement baking apparatus 10, the slurry S2 and the like can also be used as preparation raw materials.

DESCRIPTION OF SYMBOLS 1 Cement raw material apparatus 2 Main ash tank 3 Slurry apparatus 4 1st classification apparatus 5 2nd classification apparatus 6 Wet grinding apparatus 7 Reaction tank 8 Acid gas introduction apparatus 9 Solid-liquid separation apparatus 10 Cement baking apparatus

Claims (4)

Add 0.1 to 2.0 times the amount of water to the waste incineration ash and stir it into a slurry while thawing,
Classifying the incinerated ash slurry while sprinkling water into a slurry containing coarse particles and a slurry containing fine particles,
The slurry containing the classified fine particles is further classified while being sprinkled into a slurry containing coarse particles and a slurry containing fine particles,
An acid gas or acid is added to the slurry containing fine particles obtained by the second classification,
Solid-liquid separation of the slurry containing fine particles after adding the acid gas or acid,
A method for converting waste incinerated ash into a cement material, wherein the cake obtained by the solid-liquid separation is used as a cement material. The method for converting waste incinerated ash into a cement raw material according to claim 1, wherein the acid gas is exhaust gas from a cement kiln or / and exhaust gas from a chlorine bypass facility. 3. The method for converting waste incinerated ash into a cement raw material according to claim 1 or 2, wherein the maximum particle size of the fine particles obtained by the first or second classification is adjusted to 1 mm or less. A slurrying device for adding 0.1 to 2.0 times the amount of water to the waste incineration ash and stirring to make a slurry while thawing,
A first classifying device for classifying the incinerated ash slurry slurried by the slurrying device while sprinkling water into a slurry containing coarse particles and a slurry containing fine particles;
A second classifier for classifying the slurry containing fine particles classified by the first classifier while sprinkling the slurry containing coarse particles and the slurry containing fine particles;
A reaction vessel for adding acid gas or acid to the slurry containing fine particles classified by the second classifier;
An apparatus for converting waste incinerated ash into a cement material, comprising: a solid-liquid separation device for solid-liquid separation of a slurry containing fine particles discharged from the reaction tank.

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