JPS61111949A - Manufacture of aggregate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing aggregates, and more particularly to a method for producing useful aggregates from coal ash, which is a useless waste product.

(Summary of conventional technology) Currently, aggregate is used for civil engineering and construction purposes.

Aggregates are broadly divided into general aggregates using river rocks and other materials, and lightweight aggregates made by foaming raw materials in a softened or molten state.

General aggregate can only be harvested from a limited number of locations due to natural resource protection, and there is no hope for a quantitative expansion in the future. Furthermore, lightweight aggregates are natural raw materials that are mined and heat-treated, so they are considered to be subject to resource constraints.

On the other hand, coal ash is generated as the combustion residue of coal-fired power plants, has no use in itself, and is currently difficult to dispose of. Coal usually contains 15 to 20 percent by weight of mineral components, which are combusted to form coal ash, so emissions from places that consume large amounts of coal, such as coal-fired power plants, are enormous.

(Problems to be Solved by the Invention) The present invention has been made with these points in mind, and aims to produce aggregate by softening or melting coal ash, which is an unnecessary substance. In this case, if coal ash is used alone, it has the disadvantage of having a high melting temperature and requiring a lot of heat (fuel), so the purpose of this project was to establish a technology to lower the melting temperature.

(Means for solving the problem) As mentioned above, it is possible to directly heat coal ash to soften or melt it, but in reality, the temperature is 1300 to 1500°C.
The temperature is high and a large amount of heat is required, making it unsuitable for practical use.

As a result of extensive research, the present inventors have confirmed that adding iron oxide to coal ash can lower the melting temperature of coal ash.

The present invention was made based on the above findings, and involves kneading 1 to 30% by weight of iron oxide with coal, granulating it as necessary, and then heating it to soften or melt it. This is a method for producing aggregate characterized by post-cooling.

Although the rate at which the melting temperature decreases varies depending on the chemical composition of the coal ash used as the raw material, it is possible to decrease the temperature by about 400° C. at maximum.

Any type of iron oxide may be used as long as it is an iron raw material, such as reagent iron oxide, iron ore, or insect repellent red mud from aluminum smelting.

Example 1 The reagent iron oxide (Fe1
O1) was mixed in a predetermined ratio to prepare a raw material for firing.

Next, a pellet with three openings is made using a pellet preparation device.
This sample was placed in a high temperature heating microscope 8 & mirror and heated to 10℃/W.
Direct observation was performed while increasing the temperature at a temperature increase rate of in, and the melting temperature was determined when the sample had become approximately spherical.

The rate of decrease in melting temperature is shown in FIG. In Figure 1,
The vertical axis represents the decreasing melting temperature, and the horizontal axis represents the amount of iron oxide added. In the case of coal ash A, if iron oxide is added, 1~
It has become clear that adding 30% by weight of K makes it possible to lower the melting temperature. Also,
In this case, it was found that the melting temperature could be lowered the most at 15% by weight.

Table 1 Example 2 To coal ash B having the chemical composition shown in Table 2, 10 wt% of fine iron ore powder (pulverized to 88μ inertia) was added and mixed uniformly in a ball mill for 930 minutes. % by weight of methylcellulose was added, and water was further added to form a dough. Next, this glutinous material was molded into pellets of 5 .phi. using an extruder, and the pellets were air-dried.

Similarly, a system without the addition of fine iron ore powder was also molded and air-dried.

Molded object 100? was placed in a platinum dish, placed in an electric furnace maintained at 1300°C, and held for 30 minutes.

When only coal ash was used, it was only sintered, but when fine iron ore powder was added, it melted and a decrease in the melting temperature was observed.

Aggregates are obtained by naturally cooling the melt.

Table 2 Example 5 Using coal ash C having the composition shown in Table 3, an attempt was made to lower the melting temperature by adding dried red mud as an iron raw material. Coal ash C has a very high silica content and a small amount of impurity components, so it is expected to have a high melting temperature. Red mud is a red mud-like substance whose main component is iron hydroxide.

25% by weight of dry red mud was added to coal ash C, mixed uniformly in a ball mill for 1 hour, and then dried. After adding 1% of 1c PV rubber, water was added and the mixture was molded into a sphere with a diameter of 5 days using a granulator. In addition, coal ash C alone was granulated into spheres of 5 wφ.

Place 100f of each particle in a platinum dish and heat at 1400°C.
When heated for 30 minutes in an electric furnace maintained at It was done.

Table 3 shows that the present invention lowers the melting temperature of coal ash and is effective as a method for producing aggregate.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the rate of decrease in melting temperature when iron oxide is mixed with specific coal ash. Sub-agents 1) Meifuku agent Ryo Hagiwara -

Claims (1)

[Claims] A method for producing aggregate, which comprises kneading 1 to 30% by weight of iron oxide with coal, granulating it if necessary, heating it to soften or melt it, and then cooling it.