JPH05310453A - Sulfoaluminate cement comprising sludge of water purifying plant as main raw material - Google Patents

Abstract

PURPOSE:To improve rapidly hardening properities and high strength by burning sludge of water purifying plant, gypsum dihydrate and limestone as raw materials. CONSTITUTION:Sludge of water purifying plant is calcined at about 800 deg.C for about 1 hour to give calcined material of sludge comprising SiO2, Al2O3, etc. Then, about 30wt.% of the calcined material is blended with about 15wt.% gypsum dihydrate and about 55wt.% limestone to give a mixture. Then the mixture is calcined at about 1,250 deg.C, burnt and ground to produce sulfoaluminate cement. Optionally, the cement is secondarily blended with gypsum dihydrate, anhydrous gypsum hemihydrate of gypsum to give sulfoaluminate cement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sulphoaluminate cement produced by burning sludge at a water purification plant as an essential raw material and using gypsum and limestone as auxiliary raw materials at a high temperature.

[0002]

2. Description of the Related Art In order to produce sulfoaluminate cement, it is necessary to use a high-alumina raw material as an alumina source.

As seen in the literature, World Cement Technology, Vol. 9, pp. 109-118, 1978, bauxite and plagioclase are conventionally used as raw materials of high alumina quality.

[0004]

[Problems to be Solved by the Invention] In Japan, since a high-alumina raw material is not generally produced, it must be imported, and the production of sulfaluminate cement is expensive, and the location of the factory in Japan is high. Not suitable for mass production.

[0005]

From the standpoint of effective use of resources, the present invention produces sulphoaluminate cement using domestically produced wastewater treatment plant sludge as an alumina source.

[0006]

【Function】 To reduce the manufacturing cost and mass-produce the sulfaluminate cement in Japan.

[0007]

[Example] Table 1 shows the chemical composition of the sludge used in the water treatment plant.

[0008]

[Table 1]

Table 2 shows the chemical composition of the above water purification plant sludge calcined at 800 ° C. for 1 hour, and when the carbon content, that is, the activated carbon is not contained, this calcining step can be omitted.

[0010]

[Table 2]

Table 3 shows the blending ratio of the raw materials for the sulfaluminate cement clinker.

[0012]

[Table 3]

The formulations shown in Table 3 were sampled in a porcelain crucible and baked in an electric furnace at a temperature of 1250 ° C. for 1 hour to obtain a clinker.

At this stage, calcium sulphoaluminate, also known as auin, dicalcium silicate in which alpha phase, alpha dash phase and beta phase are mixed, aka berit and a small amount of calcium aluminate are produced as clinker minerals.

The clinker obtained was ground to a fineness of 300.
Cement powder of 0 g / cm ² was obtained.

Dihydrated gypsum powder was added to the above-mentioned cement powder by 0%, 5%, 10%, 20%, and 30% to prepare five types of cement powder.

The hydrated mineral of the cement paste specimen cured at room temperature in water at a water / solid ratio of 0.40 was ettringite and calcium silicate gel (C-
S-H).

Table 4 shows the results of flexural strength tests of cement paste specimens cured at room temperature in water at a water / solid ratio of 0.40 at various ages.

[0019]

[Table 4]

Table 5 shows the results of the compressive strength test under the same conditions as the bending strength test.

[0021]

INDUSTRIAL APPLICABILITY The present invention can produce a fast-setting and high-strength sulfoaluminate cement, and the secondary addition of dihydrate gypsum to the cement powder further improves and increases the strength.

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Claims (2)

[Claims] 1. A sulphoaluminate cement produced from a water treatment plant sludge, gypsum and limestone as raw materials through a firing process. 2. A sulfaluminate cement obtained by secondarily adding dihydrate gypsum, anhydrous gypsum or hemihydrate gypsum to the cement according to claim 1.