JP2001058856A - Utilization of gypsum board waste material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To utilize gypsum board waste materials by heating a feedstock comprising such gypsum board waste material, calcareous material, silicate-based material and aluminum-based material within a specific temperature range to burn off the paper and organic admixtures in the gypsum board waste material to produce hauyne-based cement clinker. SOLUTION: Gypsum board waste materials are utilized by heating a feedstock comprising such gypsum board waste material, calcareous material, silicate-based material and aluminum-based material to 1,200-1,400 deg.C pref. for 10-100 min to burn off the paper and organic admixtures in the gypsum board waste material to produce hauyne-based cement clinker; wherein the calcareous material to be used is e.g. limestone, clamshell, sewage sludge-dried powder; the silicate-based material to be used is e.g. clay, silica rock; the aluminum-based material to be used is e.g. bauxite; and the above-mentioned materials are compounded together so that hauyne consists mainly of the resulting clinker's mineral composition and the composition also contain necessary amount(s) of mineral(s) selected from belite, ferrite solid solution, gypsum and calcium aluminate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for effectively utilizing waste gypsum board. More specifically, the present invention relates to a method for removing impurities such as papers and organic admixtures contained in waste gypsum board and effectively using the waste gypsum board for gypsum for a cement composition.

[0002]

2. Description of the Related Art Gypsum board waste is conventionally disposed of by landfill or the like because there is no specific treatment method or utilization method.

However, in recent years, the necessity of resource recycling has arisen from the viewpoint of environmental protection, and a part of gypsum board waste has begun to be used as a raw material for gypsum board. However, only a few percent of gypsum board waste is used as a raw material for gypsum board, and most of this waste is still being disposed of. Therefore, there is a demand for a method of effectively utilizing waste gypsum board for uses other than gypsum board raw materials, that is, gypsum for cement compositions.

[0004]

However, the waste gypsum board contains impurities such as papers and organic admixtures used in the process of producing the gypsum board. When used for gypsum or the like, these impurities are mixed into the cement.

[0005] Mortars and concretes using such cements have an air entrainment due to the organic admixture,
There was a problem in that the strength of the specimen was significantly reduced due to the decrease in the weight of the specimen, and the plastering property and fluidity of the paper were reduced.

Accordingly, an object of the present invention is to convert gypsum board waste material into gypsum suitable for cement compositions and the like by removing impurities such as papers and organic admixtures contained in the gypsum board waste material. It is intended to provide a method for effectively utilizing waste board materials.

[0007]

Means for Solving the Problems In view of such a situation, the present inventors have conducted intensive studies and as a result, have found that waste gypsum board is 600 to
By simply heating to 1100 ° C., papers and organic admixtures contained in the waste material can be burned and removed, and a type II anhydrous gypsum (hereinafter, referred to as anhydrous gypsum) suitable for compounding a cement composition can be obtained. , And waste gypsum board, calcareous raw materials,
Raw material containing silicate raw material and aluminum raw material
It has been found that an Irwin cement clinker in which paper and organic admixture contained in the waste material are burned and removed by simply heating to 0 to 1400 ° C. has been completed, and the present invention has been completed.

That is, according to the present invention, paper and organic admixtures contained in waste gypsum board, calcareous raw material, silicate raw material and aluminum raw material are heated by heating the raw material to 1200 to 1400 ° C. Burn and remove,
Another object of the present invention is to provide a method for effectively utilizing gypsum board waste, which is characterized by producing an Irwin cement clinker.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the first aspect of the present invention, the temperature when the gypsum board waste material is heat-treated alone is 600 to 1
It is in the range of 100 ° C. When the heat treatment temperature is lower than 600 ° C., the removal of paper and organic admixtures in a short time is insufficient, and the gypsum dihydrate in the waste gypsum board in a short time is solidified as a solidifying material for soil. Anhydrous gypsum cannot be obtained, and waste materials cannot be effectively used. On the other hand, when the heat treatment temperature exceeds 1100 ° C., when the treated waste material is used for the cement, the function of suppressing the initial hydration rate of the cement (adjustment of the setting time) by gypsum may be impaired, and the workability of mortar and concrete may be impaired. It is not preferable because it may cause trouble. A particularly preferred temperature range is 60
0-800 ° C. This is because if the temperature exceeds 800 ° C., SO _x is generated from the gypsum board waste material, and equipment for treating the SO _x is required. The heating time is 10 to 1
It is preferably set to about 00 minutes, particularly about 30 to 100 minutes.

On the other hand, in the second invention, the waste gypsum board material and other cement raw materials are heated to produce an Irwin cement clinker at a temperature of 1200 to 140.
0 ° C. is preferred. If this temperature is lower than 1200 ° C., generation of Irwin is insufficient, and if it is higher than 1400 ° C., Irwin is easily decomposed, and both are not preferred. The heating time is 15 to 100 minutes, and it is 15
It is preferable to set it to about 60 minutes. Among the raw materials other than gypsum board waste used in the production of Irwin cement clinker, calcareous raw materials include limestone, shells, sewage sludge dry powder (made by adding quick lime to sewage sludge to facilitate transportation), and silicic acid. Clay, silica stone, sewage sludge and the like can be mentioned as the salty raw material, and bauxite, aluminum sludge and the like can be mentioned as the aluminum raw material. If necessary, iron raw materials such as red mud and copper flakes may be added. The mixing ratio of the gypsum board waste material and the other components is not particularly limited as long as the Irwin cement clinker can be produced. That is, Irwin (3CaO
3Al ₂ O ₃ .CaSO ₄ ) is the main component of the mineral composition of the clinker, and the mineral selected from belite, ferrite solid solution, gypsum and calcium aluminate may be contained in a necessary amount.

[0011]

EXAMPLES The present invention will be described below with reference to experimental examples relating to the performance of portland cement produced using anhydrous gypsum obtained by heat-treating gypsum board waste materials under various conditions and the performance of soil solidified materials produced using Irwin clinker. This will be described in more detail.

Example 1 After crushing gypsum board waste material, each time at 600 ° C. and 800 ° C. for 1 hour
Heat treatment was performed in the kiln. Table 1 shows untreated and heated
Replacement of treated gypsum with added gypsum for Portland cement
Of setting and mortar strength of cement used as cement
A result (JISR5201) is shown. Cement break
The specific surface area is 3200cm^Two/ G, SO_Three Is 2.0 wt%
did. The detailed formulation is as follows.

1. Mixing of raw materials for Portland cement clinker Limestone 1200 kg / t clinker Siliceous raw material 250 Iron raw material 30 Other 50

[0014] 2. Portland cement mix Portland cement clinker 97-97.5wt% gypsum 2.5-3.0wt%

The heating temperature mentioned here is the maximum temperature of the sample in the kiln, and the heating time is the time from being charged into the kiln to being discharged. Either gypsum is usually used and 25wt% or 10%
Even when 0 wt% was replaced, no accompanying decrease in mortar strength was observed.

[0016]

[Table 1]

Example 2 The gypsum of Example 1 (including untreated products) was evaluated for its performance as a gypsum for a solidifying material for soil. Table 2 shows the soil solidification strength of the solidified material trially manufactured using each gypsum. Gypsum was added to Portland cement clinker such that the SO ₃ of the solidified material was 7.5%, and the solidified material was pulverized to a Blaine specific surface area of 4500 cm ² / g. The sample soil was sandy soil (water content: 39%), silt (water content: 57%), and loam (water content: 135%). The amount of the solidifying material added to each sample soil was 4%, 5%, and 13% in wet weight ratio, respectively. After stirring and mixing the solidified material and the sample soil for 5 minutes, 5φ x 1
It was molded into a 0 cm mold and cured for a predetermined period to determine its uniaxial compressive strength (based on JIS A1216).

3. Portland cement clinker 87-90 wt% Gypsum 10-13 wt%

[0019]

[Table 2]

The solidified material using the heat-treated gypsum board waste material exhibited the same strength as the solidified material using hydrofluoric anhydride gypsum which is generally used regardless of the heating temperature. On the other hand, the strength of the solidified material using the untreated product tends to decrease, and particularly in the case of loam, it has decreased by more than 10%. The untreated gypsum was mostly gypsum dihydrate, but was changed to anhydrous gypsum by the heat treatment. Generally, gypsum for solidifying material is
It shows superior performance in anhydrous gypsum than dihydrate gypsum. Therefore, the effects of the heat treatment include the effect of dehydration in addition to the removal of papers and organic admixtures.

Example 3 Gypsum board waste was used at 1300 ° C.
By heating for 0 minutes, a clinker containing about 60% Irwin as a constituent mineral was obtained.

Blending of raw materials for Irwin clinker Limestone 700 kg / t clinker Silicic raw material 60 Gypsum 150-160 (depending on SO ₃ content and gypsum purity of other raw materials) Aluminum raw material 470

For comparison, a clinker using gypsum commonly used was also prepared. A solidified material for high water content and high organic soil (sludge) using these as a base material was trial manufactured and its performance was evaluated. Table 3 shows the results.

Mixing ratio of solidification material for sludge Irwin clinker 30 wt% Portland cement clinker 40-45 wt% Gypsum 25-30 wt%

The solidifying material is obtained by adding Portland cement clinker and gypsum to the Irwin clinker.
It was adjusted so that the Blaine specific surface area was 5000 cm ² / g and SO _{3 was} 18%. As the gypsum, the gypsum board waste material of Example 2 was heat-treated at 600 ° C. for 1 hour and hydrofluoric anhydride gypsum which is generally used was used. The sample soils were river sludge (water content 156%) and lake sludge (water content 224).
%), And the amount of the solidifying material added to the sample soil was 15% by wet weight ratio. The solidified material and the sample soil were stirred and mixed for 5 minutes, molded into a mold of 5φ × 10 cm, cured for a predetermined period, and the uniaxial compressive strength (based on JIS A1216) was determined.

[0026]

[Table 3]

The solidified material using the Irwin clinker which uses gypsum board waste material as a part of the raw material is inferior to the commonly used solidified material using the Irwin clinker which uses the gypsum as a raw material. With no results. In addition, no change was observed in the performance of gypsum board waste material that had been heat-treated at 600 ° C. for 1 hour as a gypsum to be added at the time of pulverization of the solidified material. The Irwin clinker is used not only as a solidifying material but also as a cement for building materials. Also, anhydrous gypsum is often added to these cements. It was confirmed that Irwin clinker using waste gypsum board as part of the raw material and gypsum heat treated gypsum board waste could be used without changing the performance of these cements.

[0028]

According to the present invention, waste gypsum board, which is almost completely discarded at present, is subjected to heat treatment so that it can be effectively used as a raw material for added gypsum for cement or an Irwin clinker. , Resources and environmental protection.

Continuing from the front page (72) Inventor Masao Sekiguchi 2-4-2 Daisaku, Sakura City, Chiba Prefecture Chichibu Kochi Central Research Institute, Inc. (72) Inventor Katsuyuki Sakaki 2-4-2 Daisaku Sakura City, Chiba Prefecture Chichibu Small Noda Central Research Laboratory (72) Inventor Izumi Fujimoto 2-1-1 Tsukimi-cho, Kumagaya-shi, Saitama Chichibu Onoda Central Research Laboratory (72) Inventor Hiroshi Nakanishi 2-1-1 Tsukimi-cho, Kumagaya-shi, Saitama No. 1 Chichibu Onoda Co., Ltd. Central Research Laboratory (72) Inventor Tadashi Sueoka 6276 Onoda, Onoda City, Yamaguchi Prefecture Chichibu Onoda Co., Ltd. Environmental Technology Development Center

Claims (1)

[Claims] A raw material containing gypsum board waste material, calcareous raw material, silicate raw material and aluminum raw material is 1200 to 14
A method for effectively utilizing waste gypsum board, wherein paper and organic admixtures contained in the waste are burned and removed by heating to 00 ° C., and an Irwin cement clinker is produced.