JP2003128445A - Method of converting organic polluted soil into cement raw material - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To effectively prevent secondary environmental pollution due to scattering of contaminated soil and to save fuel for the kiln when treating organic contaminated soil with a cement kiln. SOLUTION: The organic polluted soil is used as a cement raw material by packing soil contaminated with organic pollutants in a storage container, throwing the whole container into a cement kiln and burning it together with a cement raw material. Method of converting organic polluted soil into cement material.

Description

Detailed Description of the Invention

The present invention relates to a treatment method for recycling organic contaminated soil as a cement raw material and the cement. More specifically, the present invention relates to a treatment method for treating organically contaminated soil containing dioxin, PCB, cyanide or the like, when it is used as a clay raw material for cement, without causing further environmental pollution.

[0002]

2. Description of the Related Art Recently, in the vicinity of garbage incineration facilities,
Contamination due to dioxin and PCB has become a problem. Methods for detoxifying these contaminated soils include thermal desorption separation method, melt solidification method (geomelt method), alkali catalytic decomposition method, supercritical water oxidation method, mechanochemical method, vacuum heating separation method, bioremediation method, indirect method. There are heating kiln method and rotary kiln incineration method.

On the other hand, as a method for treating a contaminated soil containing a cyanide compound, an alkali chlorine method, an ozone oxidation method, an electrolytic oxidation method, a dark blue method (a sparingly soluble complex compound precipitation method), an acid decomposition combustion method, and a boiling method (cooking) High temperature combustion method), wet thermal decomposition method, adsorption method, biological treatment method and the like are known.

[0004]

However, among the above-mentioned treatment methods, the plant treatment method requires a construction cost of several hundred million yen or more, and it is also a problem to secure a destination for the treated soil. The scale of the supercritical water oxidation method and mechanochemical method is at the indoor level at present, and there is no record at the plant level. On the other hand, there are great expectations for a method of treating soil contaminated with dioxins with bioremediation. In particular, this method has advantages that the treatment cost is low and the economy is excellent because it hardly requires soil excavation, incineration fuel, chemicals or the like. Also,
It is considered to be highly safe because it uses plants. However, since the bioremediation method has a low decomposition reaction rate and a long purification / repair period, it is difficult to achieve this when the purification target is strict. Therefore, unless a technology with an innovatively high decomposition rate is developed for this treatment method and the treatment time is significantly shortened, there is a limit to its application as a remediation method due to the risk of human exposure during a long treatment period.

The present invention overcomes such problems in the conventional treatment method, and is a method of utilizing soil containing organic pollutants as a clay raw material for cement, in which case further environmental pollution. The present invention provides a processing method that does not cause

[0006]

That is, according to the present invention, there is provided a method for converting an organic polluted soil into a cement raw material and the cement thereof, which has the following constitution. (1) Organic soil characterized by being used as a cement raw material by packing soil contaminated with organic pollutants in a storage container, putting the whole container into a cement kiln, and burning it together with the cement raw material. Method for making cement soil as a raw material for cement. (2) The method of (1) above, in which soil contaminated with organic pollutants is packed in a storage container at the pollution site and the container is put into a cement kiln at a cement plant. (3) The method according to (1) or (2) above, wherein the organic pollutant is dioxin, polychlorinated biphenyl (PCB), or a cyanide compound. (4) The storage container is a plastic container, a metal container, a wooden container, or a glass container (1), (2), or
Method (3). (5) The material of the storage container is polystyrene, ABS resin, polyvinyl chloride, and the combustion temperature of the kiln is 14
The method according to (1), (2) or (3) above, wherein the temperature is 00 ° C or higher. (6) The method according to any one of (1) to (5) above, wherein the storage container is a pail, a drum or a glass bottle. (7) A cement produced by the method according to any one of (1) to (6) above.

According to the method for producing a cement raw material of the present invention, soil polluted with organic pollutants (abbreviated as organic polluted soil) is packed in a storage container, specifically, for example, sealed in a pail can or the like. Since this container is put into the cement kiln, pollutants do not scatter to the surroundings in each processing step of packing, transporting, and putting into the kiln, and environmental pollution of the surroundings can be prevented. In addition, since the packed container is put into a kiln and burned, if a plastic container such as polyethylene or polypropylene is used, considerable heat is generated at the time of burning, so use this as a part of the heat source for cement firing. Can be used,
There is the advantage of saving some calcined fuel in the cement manufacturing process.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below based on embodiments. The method of the present invention packs soil polluted with organic pollutants in a storage container, and puts the container into a cement kiln and burns it together with the cement raw material, so that the organic polluted soil is mainly used as a clay raw material for cement. This is a cement raw material method that is partially used.

The organic polluted soil is, for example, a soil polluted with dioxin, PCB, and a cyanide compound, and is a soil containing these organic pollutants. The storage container preferably has such a composition that, when fired together with the cement raw material, the trace components in the fired cement satisfy the JIS standard. That is, it is necessary that the amounts of chlorine and total alkali contained in the storage container are 0.02% or less and 0.75% or less, respectively, as the composition of the cement to be fired. By using such a container, when the contaminated soil is burned together with the container, the amount of chlorine, which is a generation source of dioxins and PCB, can be reduced as much as possible. The storage container is, for example, a plastic container such as polyethylene or polypropylene,
Metal containers such as steel, glass containers such as glass bottles, and wooden containers such as barrels. In addition, polystyrene, A
Since BS resin and polyvinyl chloride are less likely to generate dioxin when burned at a sufficiently high temperature, for example, 1400 ° C. or higher, they can be used as a container. By the way, the firing temperature of a normal cement kiln is 14
Since the temperature is about 00 ° C to 1500 ° C, a container made of polystyrene, ABS resin, polyvinyl chloride or the like can be used as long as it is a normal cement manufacturing kiln.
For steel containers such as galvanized iron and tin, the amount of iron is adjusted so that the iron content of the cement raw material does not become excessive.

The storage container is preferably a closed container such as a pail, a drum or a barrel. Put the organic contaminated soil in a closed container at the contamination site, cover it with a lid, and pack it.
The filling of the container at the contamination site may be performed manually or mechanically. For example, when the contaminated soil is put into the container at the site, it is packed in the can using a chute with a vibrator (an inclined plate equipped with a vibrating means). In addition,
The state of being packed in a container means a state in which contaminated soil is not easily scattered to the outside. For example, it means a state in which a pail can or the like is covered and sealed, or a thick plastic bag or the like is filled and the mouth is closed. By packing the organically contaminated soil in a container on site, secondary pollution due to scattering of the contaminated soil is prevented and workability is improved.

The organic contaminated soil is packed in a container, and the container is put into a cement kiln and burned together with the cement raw material. The temperature of the kiln may be a normal cement firing temperature. Due to the high temperature in the kiln, organic pollutants contained in the soil are decomposed, and the soil becomes clay and becomes a part of the clay raw material of the cement raw material. Furthermore, by burning the entire container, plastic containers such as polyethylene and polypropylene will generate high temperatures.
The combustion heat is used as part of the heat source for cement firing.

The amount of organic polluted soil input to the kiln is (a)
Standard values of chemical components defined in JIS standard of Portland cement or mixed cement, and (b) Quality control values such as hydraulic modulus, silicic acid rate, activity coefficient, lime saturation calculated from this chemical composition value. It should be managed based on.

Recently, the cement manufacturing method is almost limited to the SP system and the NSP system, and these processes have a suspension preheater and waste heat power generation equipment, and chlorine generated by decomposition of organic pollutants is generated. Gas and acid gas are adsorbed by a large amount of alkaline cement raw materials. Furthermore, the exhaust gas from the cement kiln is rapidly cooled in a short time by the waste heat boiler, so it is possible to use dioxins and PC.
B is not resynthesized. Therefore, according to this treatment method, there is no risk that dioxins will be released from the system. In addition, as a precaution, during work, it is preferable to wear respiratory protective equipment such as a dust mask, and wear protective clothing and gloves to prevent soil from adhering.

The present invention will be specifically described below with reference to examples. Dioxin content of treated soil is 1000-6
It is a soil containing dioxin that is 800 pg-TEQ / g, which greatly exceeds the national environmental standard (1000 pg-TEQ / g), and the treated amount is about 150 m ³ (about 250 t).

[Example] Dioxin-contaminated soil for which dust scattering prevention measures (sprinkling, etc.) were taken, was excavated at the contamination site using a mini backhoe, and a polyethylene pails (10 L capacity, 16 kg) was equipped with a chute with a vibrator. Used and stuffed. The amount of dust generated by this packing work is 1 m ^{3 in the} air.
The amount is 0.03 to 0.06 mg per day, and the dioxin concentration in the air is 0.204 to 0.408 pg-TEQ / Nm ³ even when converted based on the soil in which the dioxin concentration was high.
It satisfied the national environmental standard (0.6 pg-TEQ / Nm ³ ). Pail cans filled with contaminated soil were further stored in a container, packed, transported by truck to a cement factory, and put into the kiln using an existing chute. In addition,
A pail can of about 300 mm square was used according to the existing chute, but the size of the pail can is not limited as long as it can be put into the kiln. No soil loss was observed during and after truck transport. Therefore, the total amount of soil in the pail can was put into the cement kiln. During transportation, wing cars were used to prevent spills. After transportation, it was installed at a temporary storage location in the cement plant. During these operations, workers wore respiratory protective equipment such as dust masks, protective clothing and soil-resistant gloves that were resistant to soil. These protective gears were discarded after each work, new ones were worn, and after use, they were incinerated in a kiln.
Contaminated soil put into the kiln together with cement raw materials for about 1
Approximately 250 hours at 450 ℃, about 36,000 cement
manufactured. By the way, it occurred when the soil was not put in a container at the polluted site, it was loaded on a truck in bulk and transported to a cement factory, the contaminated soil was transferred to the kiln input port using a belt conveyor, and the scoop was put into the kiln. The dioxin concentration converted from the amount of dust was 3.0 pg-TEQ / Nm ³ , which exceeded the national environmental standard.

In this embodiment, about 16,000 polyethylene pail cans were used. The empty weight of this pail can is 0.
It is 5 kg / piece, and the total weight of the added polyethylene cans is 8
It is 000 kg. The combustion heat of polyethylene is about 11,000 kcal / kg for both soft and hard, so cement is about 36
Approximately 11,000 kcal / kg x for producing 000t
This means that the fuel equivalent to the heat quantity of 8000 kg = 88 × 10 ⁶ kcal can be saved. Even if a polypropylene pail can is used, fuel equivalent to the heat quantity of 88 × 10 ⁶ kcal can be saved.

When the steel pail can has the same size as the above, the empty weight is about eight times as large as that of the polyethylene pail. Therefore, the cement raw material iron is 8000 kg × 8 = 6.
It can be reduced by 4000 kg. However, galvanized iron, tin plate, and stainless steel contain zinc, tin, and chromium in addition to iron, which are not preferable for mixing with cement, so these cans should be avoided. Further, when a glass bottle is used, the silica source is the most expensive of the cement raw materials, and is therefore a suitable silica raw material. However, if added in excess, there is a concern that the total amount of alkali in the cement will exceed the JIS standard 0.75%, so care must be taken not to exceed this.

Dioxin-contaminated soil was treated at a rate of 10 t / day (10 hours operation), and 220 t was fired for 1 month (22 working days). The dioxin concentration in the gas discharged from the cement kiln exhaust gas during the firing process and in the clinker, which is a product of the cement factory, was measured. As a result, no significant difference was found in the dioxin concentration in the exhaust gas before and during the treatment. In addition, when the general properties of the cement such as strength, setting property, and heat of hydration property of the obtained cement were evaluated, it was found that the cement according to the present invention is a conventional cement produced without adding contaminated soil. It was confirmed to be similar to.

[0019]

EFFECTS OF THE INVENTION The treatment method of the present invention detoxifies soil contaminated by dioxin, etc. for which a practical treatment method has not been established, and makes it usable as a cement raw material. The secondary environmental pollution due to the scattering of contaminated soil during the treatment work can be effectively prevented, and the fuel in the kiln can be saved by putting the whole container into the kiln and burning it.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akitoshi Kitachi             2-4 Daisaku, Sakura City, Chiba Prefecture Pacific Ocean             Central Research Institute of Cement Co., Ltd. (72) Inventor Osamu Yamaguchi             2-4 Daisaku, Sakura City, Chiba Prefecture Pacific Ocean             Central Research Institute of Cement Co., Ltd. (72) Inventor Toshiro Goto             25 Taito-cho, Kochi City, Kochi Prefecture Taiheiyo Cement Co., Ltd.             Ceremony company Tosa factory (72) Inventor Terumi Haraguchi             3-8-1, Nishikanda, Chiyoda-ku, Tokyo             Heiyo Cement Co., Ltd. (72) Inventor Jun Nagai             3-8-1, Nishikanda, Chiyoda-ku, Tokyo             Heiyo Cement Co., Ltd. (72) Inventor Akihiro Yokota             841-3 Hasuike, Tosa City, Kochi Prefecture F-term (reference) 4D004 AA41 AB05 AB06 AB07 AC07                       BA02 BB09 CA28 CA30 CB02                       CC13 CC17                 4G012 KA02 KA08

Claims (7)

[Claims] 1. The soil contaminated with organic pollutants is packed in a storage container, and the whole container is put into a cement kiln and burned together with the cement raw material to use the organic polluted soil as a cement raw material. Method for converting organic contaminated soil into a cement raw material. 2. The method according to claim 1, wherein soil contaminated with organic pollutants is packed in a storage container at the site of contamination, and the whole container is put into a cement kiln at a cement factory. 3. The method according to claim 1, wherein the organic pollutant is dioxin, polychlorinated biphenyl (PCB), or a cyanide compound. 4. The container according to claim 1, wherein the storage container is a plastic container, a metal container, a wooden container, or a glass container.
Method 2 or 3. 5. The material of the storage container is polystyrene or ABS
The method according to claim 1, 2 or 3, which is a resin or polyvinyl chloride and has a kiln combustion temperature of 1400 ° C or higher. 6. The method according to claim 1, wherein the storage container is a pail can, a drum can or a glass bottle. 7. A cement produced by the method according to claim 1.