JP2010234177A - Method of utilizing neutralized filtrate of treating solution for making asbestos harmless - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of utilizing a neutralized filtrate of a treating solution for making asbestos harmless which reduces the costs for treating waste water of the neutralized filtrate of a treating solution for making asbestos-containing waste harmless and allows reuse of the neutralized filtrate in a treatment of making an asbestos-containing waste harmless and as a raw material for cement. <P>SOLUTION: The method of utilizing a neutralized filtrate of a treating solution for making asbestos harmless includes: treating asbestos-containing waste with a treating solution containing hydrochloric acid and a fluorine-containing compound to make asbestos in the waste harmless; neutralizing the treating solution by adding slaked lime to the treated waste solution; filtrating the resultant precipitation to obtain a neutralized filtrate; adding sulfuric acid to the neutralized filtrate and filtering; and reusing the resultant solid content as a raw material for cement and the resultant filtrate as a treating solution for making asbestos-containing waste harmless. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of using a neutralized neutralized filtrate of asbestos, and in particular, a neutralized filtrate obtained by neutralizing a treatment liquid obtained by detoxifying waste material containing asbestos, The present invention relates to a method for using an asbestos-detoxified neutralized filtrate that is reused in a hydrotreating process.

  Asbestos materials have been widely used in various fields because strength does not decrease over a long period of time. Slate plates, water pipes, fireproof coating materials, brake pads, gaskets, heat insulation plates, ropes, packing, acetylene cylinders It has been used in many parts as a filler.

In particular, conventional cement-based boards, etc. have been used for spray construction products, ceilings, wall materials, etc. as fireproof coating materials because they are excellent in fire resistance, sound insulation, heat insulation, etc. Many conventional cement-based boards contain asbestos.
However, asbestos has recently been found to cause many health problems such as asbestosis, lung cancer, malignant mesothelioma, and its use has been banned, and it must be disposed of and detoxified immediately. It has become.

  Conventional asbestos-containing waste materials are handled as general waste, and are currently disposed of as industrial waste. However, asbestos is scattered and emitted, and sufficient safety measures are required.

  Also, the demolition of buildings using building materials such as cement-based boards containing asbestos, such as fireproof coverings and collapsed ceiling boards, has peaked, but there are problems with asbestos exposure and asbestos scattering and dissipation. It is getting serious.

Such asbestos is a naturally occurring mineral fiber, and serpentinite chrysotile (3MgO 2SiO ₂ 2H ₂ O), amphibole amosite ((Mg, Fe) ₇ Si ₈ O ₂₂ (OH) ₂ ), Crocidolite (Na ₂ Fe ₃ ²⁺ Fe ₂ ³⁺ Si ₈ O ₂₂ (OH) ₂ ), anthophyllite (Mg ₇ Si ₈ O ₂₂ (OH) ₂ ), tremolite (Ca ₂ Mg ₅ Si ₈ O ₂₂ (OH) ₂ ), actinolite (Ca ₂ (Mg, Fe) ₅ Si ₈ O ₂₂ (OH) ₂ ).
Such serpentine chrysotile is known to dehydrate and transform at about 700 ° C. when heated and to be harmless forestlite (2MgO · SiO ₂ ) at about 900 ° C. Therefore, it is difficult to achieve effective utilization.

Since the harmfulness of such asbestos is derived from the fiber, the following method has been proposed as a method of detoxifying the fiber by modification and melting.
JP-A-2008-246445 (Patent Document 1) discloses a method for detoxifying asbestos in which a waste material containing asbestos is dissolved and detoxified with an acid to react with calcium or magnesium to produce a water-soluble salt. The first acid which dissolves the asbestos-containing waste material with the first acid is contacted with the second acid that reacts with calcium or magnesium to form a water-insoluble salt, and is insoluble in water. An asbestos detoxification method comprising a second step of precipitating a salt and a third step of solid-liquid separation of the treatment liquid of the second step is disclosed.

  JP 2009-029660 A (Patent Document 2) discloses neutralizing a solution after detoxifying an asbestos-containing waste material using a treatment aqueous solution containing a fluorine-containing compound and a mineral acid, A method for producing a cement clinker is disclosed, in which the generated precipitate is blended as a raw material for producing a cement clinker containing calcium fluoroaluminate.

  Furthermore, in JP 2008-273748 A (Patent Document 3), asbestos contained in the waste material is made non-asbestos by impregnating the waste material containing asbestos and calcium with sulfuric acid, A method for producing cement is disclosed, in which a detoxified product obtained by reacting with sulfuric acid to produce gypsum is blended as a gypsum source during cement production.

  However, the conventional asbestos-containing waste material detoxification method does not fully utilize the neutralized filtrate after neutralization obtained from the treatment of asbestos-containing waste, particularly after filtering the neutralization treatment liquid Since the filtrate contains ions such as calcium, chlorine, and fluorine that cannot be removed by neutralization, the filtrate requires sufficient drainage treatment. Therefore, the drainage treatment requires sufficient facilities and expensive. Expense was necessary.

JP 2008-246445 A JP 2009-029660 A JP 2008-273748 A

The object of the present invention is to eliminate the above-mentioned problems, reduce the wastewater treatment cost of the filtrate after neutralization of the treatment liquid detoxified asbestos-containing waste material, and further use the neutralized filtrate as a waste material containing asbestos. It is intended to provide a method for using an asbestos-detoxified neutralized filtrate that can be reused for detoxification and can also be used as a cement raw material.
In particular, the object of the present invention is to reuse the solid content obtained from the filtrate by the neutralization treatment as a gypsum raw material for cement, and as an acid for detoxifying the asbestos-containing waste material by purifying the filtrate. It is to provide a method for using the asbestos-detoxifying neutralized filtrate that can be used.

  In order to solve the above-mentioned problems, the method of reusing the asbestos-detoxifying neutralized filtrate of the present invention comprises detoxifying asbestos contained in the waste material with a treatment solution containing hydrochloric acid and a compound containing fluorine. The resulting treatment solution is neutralized by adding slaked lime, and the resulting precipitate is filtered and sulfuric acid is added to the resulting neutralized filtrate to precipitate a solid, followed by further filtration. In addition, the obtained precipitate is reused as a cement raw material, and the filtrate is reused as a detoxification treatment solution for asbestos-containing waste material.

  Preferably, in the method of reusing an asbestos-detoxifying neutralized filtrate of the present invention, hydrochloric acid contained in the filtrate is distilled by adding sulfuric acid to the neutralized filtrate and distilling the filtrate obtained after filtration. A method for reusing an asbestos-detoxified neutralized filtrate, comprising purifying and using the purified hydrochloric acid as hydrochloric acid in a solution for detoxifying asbestos-containing waste material.

  Preferably, in the method for reusing an asbestos detoxification neutralized filtrate of the present invention, the solid content precipitated by adding sulfuric acid to the neutralized filtrate is used as a gypsum raw material for cement production. And reusing the asbestos-detoxified neutralized filtrate.

  More preferably, in the recycle method of the asbestos-detoxifying neutralization filtrate of the present invention, the precipitate generated after the neutralization is used for producing a cement clinker, This is a method for recycling the neutralized filtrate.

By the method of reusing the asbestos-detoxified neutralized filtrate of the present invention, the neutralized filtrate obtained after neutralization of the treatment solution obtained by detoxifying the asbestos-containing waste material can be effectively reused.
In particular, in the past, since salt such as calcium chloride was contained in the neutralized filtrate after neutralizing the detoxification treatment solution of asbestos-containing waste material, wastewater treatment took a lot of time and money. By further treating the Japanese filtrate with sulfuric acid, the neutralized filtrate can be reused for detoxifying the asbestos-containing waste material, and can also be used as a cement raw material, thus reducing wastewater treatment costs. It becomes possible.
Furthermore, the precipitate obtained by the neutralization treatment can be reused as a raw material for cement clinker.
Thus, in this invention, the recycling of the neutralization process filtrate after detoxifying the asbestos-containing waste material is achieved, and the cost of the detoxification waste liquid process can be reduced.

Furthermore, for example, fluorite (CaF ₂ ), bauxite (Al ₂ O ₃ ), iron oxide raw material, and raw material of silica can be used as the precipitate after neutralizing the waste treatment liquid obtained by detoxifying the asbestos-containing waste material. Since an alternative is included, it can be used as a raw material for a cement clinker containing a cement raw material, particularly calcium fluoroaluminate, thereby enabling a reduction in cement manufacturing cost.

It is the flowchart figure which represented typically an example of the reuse method of the asbestos-detoxification process neutralization filtrate of this invention. It is process drawing which shows schematically the cement finishing process using the gypsum obtained from the neutralized filtrate in this invention. It is process drawing which shows the outline which manufactures the cement clinker (sintered body) using the precipitate obtained from the neutralization process in this invention.

The method for recycling the asbestos-detoxifying neutralized filtrate of the present invention will be described in detail below.
The method of reusing the asbestos-detoxifying neutralized filtrate of the present invention is to detoxify the asbestos in the waste material with a treatment solution containing hydrochloric acid and a fluorine-containing compound asbestos-containing waste material, and to the resulting treatment solution The treated solution is neutralized by adding slaked lime, and the resulting precipitate is filtered, and sulfuric acid is added to the resulting neutralized filtrate to precipitate a solid, followed by further filtration. In this method, the asbestos-detoxified neutralized filtrate is reused as a cement raw material and the filtrate is reused as a detoxifying solution for asbestos-containing waste materials.

FIG. 1 is a flowchart schematically showing an example of a method for reusing an asbestos detoxification neutralized filtrate of the present invention.
In the present invention, the waste material containing asbestos to be detoxified is not only asbestos itself, but also waste material containing asbestos used in building materials such as asbestos-containing slate plates and asbestos-containing spray waste materials. In particular, waste materials generated by disassembling the asbestos-containing sprayed construction products that are expected to be released in large quantities in the future and in which asbestos scattering / release is particularly problematic can be used effectively. .
Further, for example, the recovered asbestos-containing slate plate contains organic additives such as pulp fibers, but can be easily separated by filtering the residue after the acid treatment of the present invention.

  Further, in the waste material, not only calcium itself, but also minerals contained in cement such as calcium oxide, calcium hydroxide, alite, belite, calcium aluminate, ferrite, etc. that function as a calcium source, or hydrates thereof The cement component of such compounds is included.

First, in the present invention, the asbestos-containing waste material first detoxifies the contained asbestos with a treatment aqueous solution containing hydrochloric acid and a compound containing fluorine.
Hydrochloric acid can be suitably used because it can dissolve the high-pH cement binder contained in the asbestos-containing waste material.

The concentration of such hydrochloric acid can be appropriately set according to the situation at the site and is not particularly limited, but it is not particularly limited as long as the reaction to the asbestos non-asbestos reaction occurs. be able to. Suitably, it is desirable that the resulting aqueous treatment solution has a pH of 1 or less.
This is because it is possible to dissolve the high-pH cement-based binder contained in the asbestos-containing waste material in a shorter time when the pH of the resulting aqueous treatment solution is 1 or less.
Further, during the detoxification treatment of asbestos in the asbestos-containing waste material using such a treatment aqueous solution, that is, while the treatment aqueous solution and the asbestos-containing waste material are brought into contact by immersion or the like, It is preferable that the pH is always kept at 1 or less from the viewpoint of shortening the time for dissolving the high pH cement binder contained in the waste material. This means that the hydrochloric acid contained in the treatment aqueous solution is asbestos. It can hold | maintain by adding as needed during the detoxification process of a contained waste material.

The fluorine-containing compound contained in the treatment aqueous solution is not particularly limited as long as it is a water-soluble compound. For example, alkali metal, alkaline earth metal or ammonia tetrafluoroborate, hexafluorosilicate, fluorine. And a compound containing fluorine soluble in at least one water selected from the group consisting of fluoride salts and hydrofluoric acid. Preferably, a compound containing fluorine soluble in at least one kind of water selected from the group consisting of alkali metal, alkaline earth metal or ammonia fluoride salts, and hydrofluoric acid.
Examples of the fluoride salt include fluorides, difluorides, and mixtures of alkali metals, alkaline earth metals, or ammonia.
Fluorides that can be used particularly preferably are ammonium fluoride and hydrofluoric acid.

By containing such a fluorine-containing compound in the treatment aqueous solution, the SiO ₂ skeleton of asbestos can be destroyed.
The amount of the fluorine-containing compound added is such that the fluoride ion concentration in the treatment aqueous solution is 1.5 to 20% by mass, particularly preferably 2.5 to 10 to be added.
By adding a fluorine-containing compound in such a range, it is possible to have the function of being able to dissolve the SiO ₂ skeleton of asbestos more efficiently.

  Asbestos in the asbestos-containing waste material is obtained by bringing the asbestos-containing waste material into contact with the treated aqueous solution using the above-mentioned treated aqueous solution, specifically, by immersing the asbestos-containing waste material in the treated aqueous solution and allowing it to stand or stir. And the treatment aqueous solution can be effectively brought into contact with each other, and asbestos can be rendered harmless.

  In that case, as described above, it is preferable to maintain the pH of the treatment aqueous solution at 1 or less, and as the retention method, hydrochloric acid contained in the treatment aqueous solution is appropriately added during the detoxification treatment. And a method of maintaining the pH at 1 or less.

The blending ratio of the treatment aqueous solution to the asbestos-containing waste material in the asbestos-detoxifying treatment in the present invention can be arbitrarily set depending on the amount of asbestos and the amount of cement-based binder contained in the asbestos-containing waste material, but is preferably 0 by mass ratio. .5 to 100, more preferably 1 to 20.
When the mass ratio is within the above range, the increase in the pH of the aqueous solution due to the reaction between hydrochloric acid and the cement-based binder can be further suppressed, the treatment can be further performed for a short time, and the treatment efficiency can be improved. The cost of the subsequent waste liquid treatment can be suppressed at a lower cost.

  In this way, preferably, by using a treatment aqueous solution having a specific fluorine ion concentration range at a pH of 1 or less, it is possible to effectively prevent the asbestos-containing waste material of any form from being effectively prevented from being scattered and released, such as asbestos dust. In addition, it can be easily detoxified in a short time to 0.1% by mass or less as defined by the Ministry of Health, Labor and Welfare.

Asbestos is made non-asbestos and detoxified by sufficiently immersing the asbestos-containing waste material in a treatment solution containing hydrochloric acid and a compound containing fluorine. Therefore, it can be set as the harmless processed material which became easy to handle.
Here, non-asbestosization means that asbestos and an acid react with each other and needle crystals such as chrysotile, crocidolite, and amosite are converted into other substances. It is harmless to the human body.

Moreover, when performing the said acid treatment of asbestos containing waste material, it is preferable to crush and grind | pulverize the said waste material in an airtight state, and to acid-treat.
Here, the sealed state means a state in which asbestos is not in direct contact with free air in the working environment (excluding the air in the sealed space). For example, a crushing / pulverizing machine that can be sealed by a case, A state realized using a transfer means that can be sealed by a case from a pulverizer to an acid treatment container, or an acid treatment container that can be sealed by a case, or preferably, the asbestos-containing waste material is immersed in the acid for acid treatment. And the like.
Thus, by crushing and pulverizing the asbestos-containing waste material, it is possible to easily make the asbestos non-asbestos by the above acid treatment, and to make it a harmless treatment product, and the detoxification time can be carried out in a short time. It becomes possible.

In particular, when asbestos-containing waste material is immersed in an acid to be crushed and crushed and pulverized, the asbestos and calcium-containing waste material is made harmless by crushing and pulverizing so that asbestos is not scattered or released. The acid treatment step to be treated can be preferably performed simultaneously.
In addition, since it is sufficient that the asbestos-containing waste material is in a wet state due to at least an acid, the crushing and pulverization may be performed while the asbestos-containing waste material is immersed in an acid as described above, or the asbestos-containing waste material may be If it becomes wet when immersed in an acid, it may be taken out from the acid and crushed and crushed.

Other methods of crushing and crushing asbestos-containing waste materials in a sealed state include crushing and crushing machines that can be sealed by a case, transfer means that can be sealed from the crushing and crushing machine to the acid treatment container, or sealing by a case. There is a method using a possible acid treatment vessel.
As the method, a crushing / pulverizing machine, a transfer means and an acid treatment container are arranged, and each of these devices is covered with a single sealed case, or the crushing / pulverizing machine, the transfer means and the acid treatment container can be sealed. As a specification, there is a method of connecting each device with a seal.

As means for crushing and crushing asbestos-containing waste materials, known means for crushing and crushing building material waste materials can be used.
In particular, impact crushers, hammer crushers, ball mills, vertical mills, tower mills, and the like can be cited as specifications that can seal individual devices.
As a result, for example, the asbestos-containing waste material having a large size such as a slate plate can be completely made non-asbestos with the acid.

Subsequently, slaked lime is added to the treatment solution after detoxifying the asbestos-containing waste material, neutralization treatment is performed, and solid-liquid separation filtration is performed between the precipitate and the neutralized filtrate.
Specifically, asbestos-containing waste material is soaked in the above detoxified aqueous solution, insoluble matter (pulp fiber, etc.) is filtered, slaked lime is added to the filtrate to neutralize, and the generated precipitate is filtered. , Dehydrated to obtain a precipitate cake, or by soaking the asbestos-containing waste material in the detoxification solution and neutralizing it by adding slaked lime without filtering insoluble matter (pulp fibers, etc.) Then, filtration and dehydration may be performed to obtain a precipitate cake.
The precipitate cake includes calcium fluoride (CaF ₂ ), iron hydroxide (Fe (OH) ₃ ), aluminum hydroxide (Al (OH) ₃ ), magnesium hydroxide (Mg (OH) ₂ ), silicic acid compounds, etc. Precipitates are generated, and cakes containing these precipitates may be blended as raw materials for the production of cement clinker used for cement raw materials, particularly cement clinker containing calcium fluoroaluminate, cement for which quick hardening is desired. it can.

As a cement containing calcium fluoroaluminate, for example, ultrafast cement can be exemplified.
When producing a cement containing calcium fluoroaluminate, which is a cement that desires rapid hardening such as jet cement, in addition to the raw materials used for ordinary Portland cement, fluorite (CaF ₂ ), bauxite (Al ₂ O ₃ ) is used as a raw material, and it is necessary to generate calcium fluoroaluminate 11CaO · 7Al ₂ O ₃ · CaF ₂ which is a fast-hardening component contained in the cement. Therefore, the precipitate generated by neutralization is filtered. The dehydrated cake can be used as a raw material for cement, preferably as a raw material for the cement clinker.

The precipitate, preferably the precipitate cake, is then used as a raw material to produce a cement, for example, a cement clinker containing calcium fluoroaluminate in particular.
FIG. 3 is a process diagram showing an outline for producing a cement clinker (sintered body) using a precipitate obtained by the neutralization treatment in the present invention.
The process for producing such cement clinker is roughly divided into a raw material process, a firing process, and a finishing process.
Furthermore, the raw material process is roughly divided into a raw material receiving process and a pulverizing / classifying process.
In the raw material receiving process, first, a cement clinker firing raw material transported from the outside, that is, limestone is mainly used. The precipitate, fluorite (CaF ₂ ), bauxite (Al ₂ O ₃ ), clay Etc. are received and sorted by hopper 9 and received.
When the raw material is a large lump, a crusher (not shown) is provided downstream of the receiving hopper 9, and after crushing to a predetermined particle size, each raw material is stored in the raw material storage 10 by the transporter. The

In the subsequent pulverization / classification process in the raw material process, the raw material in the raw material storage 10 is mixed and pulverized by a “raw material pulverizer” (raw material mill), and classified by a “classifier” to prepare a stable powder raw material.
Currently, a “vertical mill” 11 having many functions of drying, pulverization, and classification of coarse powder and fine powder is widely used as the raw material pulverizer.
Then, the obtained powder raw material is uniformly mixed by, for example, the blending silo 12 and then introduced into the raw material storage silo 13.
In the present invention, like the other raw materials, the precipitate is introduced into the receiving hopper 9 and separately stored as the raw material, and is introduced into the pulverizer 11 or is not particularly stored. 11 may be introduced directly or may not be introduced in this raw material process.
If necessary, the precipitate is preferably subjected to a drying step before mixing and grinding.

Next, the powder raw material prepared through the raw material process is subjected to a firing process.
This firing process is a process in which the powder raw material is heated until it reaches a predetermined temperature, and fired so as to exhibit hydraulic properties as cement.
Such a firing process is roughly divided into a cement kiln supply process, a firing process, and a cooling process.
In the cement kiln supply step, first, the powder raw material is put into a preheating device (preheater) 14 and heated, and then put into a rotary kiln 16.

The cement raw material charged into the preheating device 14 is heated to 800 to 900 ° C. while descending the preheating device 14.
The heating of the cement raw material in the preheating device 14 is performed by sending hot air into the preheating device 14.
Most of the preheating devices 14 are provided with a calcining furnace 15 in the lower stage.

  In the firing process, the cement raw material heated by the preheating device 14 and sent to the cement rotary kiln 16 is fired at a high temperature of about 1500 ° C. while rotating in the rotary kiln 16 2 to 3 times per minute. The cement clinker is removed from the rotary kiln 16.

The cement raw material is fired in the rotary kiln 16 by burning pulverized coal from the front of the rotary kiln 16 toward the kiln (side from which the sintered body is taken out) toward the kiln bottom (side where the cement raw material is charged). The temperature inside the rotary kiln 8 is about 1000 ° C. at the bottom of the kiln, the maximum temperature is about 1400-1500 ° C., and the temperature before the kiln is about 1200 ° C.
Then, the sintered body taken out from the rotary kiln 16 is sent to the cooler 17.
In the cooling process, the sintered body taken out from the rotary kiln 16 is rapidly cooled by forced air cooling in the cooler 17 and sent to the finishing process.

  In the present invention, the precipitate can be melt-treated with the cement kiln, whether it is introduced into the preheating device 14 through the raw material process, introduced in front of the kiln of the rotary kiln 16, or introduced at the bottom of the kiln. If it exists, the supply timing is not particularly limited.

As described above, the precipitate introduced into the rotary kiln together with the cement raw material is heat-melted, for example, at 1000 to 1500 ° C. for 20 to 60 minutes while rotating in the rotary kiln.
At this time, it is preferable that the maximum temperature is 1450 ° C. or higher and the time for heating at a temperature of 1450 ° C. or higher is 5 minutes or longer.
A cement clinker is formed by this heat treatment.

Moreover, when performing such a melting process, it is also possible to add a flux as needed.
Examples of the flux include boric acid compounds such as boric acid, borax, calcium borate, and boronite calcite, phosphoric acid compounds such as phosphoric acid, sodium phosphate, and calcium phosphate, silicic acid, sodium silicate, and potassium silicate. Silicate compounds, carbonate compounds such as sodium carbonate, potassium carbonate, and lithium carbonate, barium compounds such as barium carbonate and barium sulfate, and fluorine compounds such as hydrogen fluoride, cryolite, and calcium fluoride can be used.

If the amount of such a fluxing agent is small, melting may be slow or inhomogeneous, so it is desirable to add the above amount of flux in the melting process, but it is not always necessary to add it.
Such a flux has a function of reducing the melting point during melting or shortening the melting time.

On the other hand, neutralization obtained by adding slaked lime to the treatment solution after detoxifying the above asbestos-containing waste material, performing neutralization treatment, and performing solid-liquid separation filtration between the precipitate and the neutralized filtrate Sulfuric acid is added to the filtrate to precipitate dihydrate gypsum, followed by solid-liquid separation and filtration.
The main component of the neutralized filtrate is calcium chloride, and by adding sulfuric acid to this, calcium and sulfuric acid react to precipitate dihydrate gypsum. Can be used as

In order to produce cement, for example, as shown in FIG. 3 described above, a cement clinker is prepared by roughly dividing into a raw material process, a firing process, and a finishing process.
Next, in order to produce cement powder, gypsum having a function of adjusting the hardening rate of cement is added to a cement clinker, and the mixture is pulverized to form a powder.
In the present invention, dihydrate gypsum which is a precipitate obtained by treating the neutralized filtrate with sulfuric acid can also be used as a gypsum source to be mixed with cement clinker in the finishing step.

As shown in FIG. 2, specifically, for example, the cement clinker supplied from the cement clinker silo 1 in which the cement clinker is stored is first pulverized by the preliminary pulverizer 3.
Dihydrate gypsum, which is a precipitate obtained by treating the neutralized filtrate with sulfuric acid, is stored in the gypsum yard 2 as a gypsum source.
The pre-ground cement clinker and dihydrate gypsum which is a precipitate obtained by treating the neutralized filtrate supplied from the gypsum yard 2 with sulfuric acid are introduced into a cement pulverizer (finishing mill) 4 and pulverized. Mix.
The obtained pulverized mixture is introduced into the separator 5, and a powder having a desired particle size range is obtained as Portland cement 7.

Further, the cement powder having a large particle size in the separator 5 is again introduced into the cement pulverizer (finishing mill) 4 and pulverized.
If necessary, fly ash or blast furnace slag powder is added to the cement powder adjusted to the desired particle size range by the separator 5 and mixed uniformly by the mixer 6 to prepare fly ash cement or blast furnace cement 8. You can also

For example, in the case of producing ordinary Portland cement, the blending ratio of gypsum in the cement is about 2 to 3% by mass in terms of SO ₃ .
Therefore, the mixing limit of the present dihydrate gypsum to ordinary Portland cement can be up to about 2 to 3% by mass in terms of SO ₃ .

In addition, sulfuric acid is added to the neutralized filtrate obtained by carrying out solid-liquid separation filtration with the above neutralized filtrate to precipitate dihydrate gypsum, and this is further subjected to solid-liquid separation filtration of the filtrate obtained. The main component is hydrochloric acid.
The filtrate containing hydrochloric acid as a main component can be used as it is as hydrochloric acid applied to the asbestos detoxification treatment of the present invention, but in order to further increase the concentration, the filtrate is purified by distillation. Concentrated hydrochloric acid is preferably used as hydrochloric acid applied to the asbestos detoxification treatment in order to maintain the pH of the detoxification treatment solution at p1 or less.
In addition, since the filtrate mainly composed of hydrochloric acid contains low-concentration distilled components and distillation residues other than hydrochloric acid, a distillation means is used to remove these and purify hydrochloric acid.
Distilled components other than concentrated hydrochloric acid obtained by distilling the filtrate containing hydrochloric acid as a main component are subjected to drainage treatment, but the treatment cost is reduced because the chlorine concentration is low and the treatment amount is also small.

  Thus, the utilization method of the asbestos-detoxified neutralized filtrate of the present invention can detoxify asbestos and can effectively utilize the neutralized filtrate in the process.

  The utilization method of the neutralized asbestos-treated neutralized filtrate of the present invention can be applied not only to slate waste materials but also to the treatment of many other materials that use asbestos, and to produce cement that reuses the neutralized filtrate. It becomes possible to apply to.

DESCRIPTION OF SYMBOLS 1 Cement clinker silo 2 Gypsum yard 3 Pre-grinding machine 4 Cement grinder 5 Separator 6 Mixer 7/8 Cement silo 9 Raw material receiving hopper 10 Raw material storage 11 Raw material grinder 12 Blending silo 13 Raw material storage silo 14 Preheating device (preheater)
15 Calcining furnace 16 Cement rotary kiln 17 Cooling machine

Claims (4)

  Asbestos-containing waste material was detoxified with a treatment solution containing hydrochloric acid and a compound containing fluorine, and the treatment solution was neutralized by adding slaked lime to the resulting treatment solution, resulting in Sulfuric acid is added to the neutralized filtrate obtained by filtering the precipitate to precipitate solids and further filtered. The obtained precipitate is reused as a cement raw material, and the filtrate is made harmless to asbestos-containing waste materials. A method for reusing an asbestos-detoxifying neutralized filtrate, characterized by being reused as a treatment solution.   In the recycling method of the asbestos detoxification neutralized filtrate according to claim 1, the hydrochloric acid contained in the filtrate is purified by distilling the filtrate obtained by adding sulfuric acid to the neutralized filtrate and filtering, A method for reusing an asbestos-detoxified neutralized filtrate, wherein the purified hydrochloric acid is used as hydrochloric acid in a solution for detoxifying asbestos-containing waste.   The method for reusing an asbestos-detoxifying neutralized filtrate according to claim 1 or 2, wherein the solid content precipitated by adding sulfuric acid to the neutralized filtrate is used as a gypsum raw material for cement production. , How to recycle asbestos detoxification neutralized filtrate.   The method for reusing an asbestos-detoxifying neutralized filtrate according to any one of claims 1 to 3, wherein the precipitate generated after the neutralization is used for producing a cement clinker, To recycle the neutralization filtrate.

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