JPH0742148B2 - Method of firing artificial fine aggregate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for firing artificial fine aggregates, and more particularly to the use of artificial fine aggregates having a particle size of 5 mm or less, which are used as aggregates of artificial sand or concrete. Regarding the firing method.

[Conventional technology]

As an effective utilization technology of fly ash generated by the use of coal, there is a technology of granulating and firing fly ash to produce an artificial lightweight aggregate. Specifically, flammable carbonaceous materials (fine powder of coal and coke) are added to fly ash containing a small amount of unburned carbon, and kneaded and granulated with water as a binder to produce raw pellets. Then, while supplying and transporting the raw pellets onto a moving grate, the pellets are dried and preheated if necessary, and then ignited, fired, kept heat and cooled to obtain an artificial lightweight aggregate.

An example of manufacturing an artificial fine aggregate using the above-mentioned technique is disclosed in Japanese Patent Laid-Open No. 59-39758.

That is, what is disclosed in this publication is that when a moving grate is used to feed fine aggregate raw pellets on the moving grate in a conventional manner and then the pellets are fired, even if the firing conditions are variously changed. Since the ventilation in the layer of lumber pellets is obstructed, the pellets are fused and found to be a normal pellet (fine aggregate), and in order to eliminate this drawback,
When the fine aggregate raw pellets are fired, the fine aggregate raw pellets are manufactured by adding and mixing the already fired fired pellets having the same particle size as the raw pellets. .

[Problems to be Solved by the Invention]

However, in the method disclosed in the above-mentioned JP-A-59-39758, although only fine aggregate is fired, it has various advantages, but it is a mixture with the raw pellets of fired fine aggregate and the particle size is Due to its small size, the ventilation in the layer of pellets has not been completely improved, and the problem remains that raw fine aggregate pellets may be burnt. In addition, it is possible to reduce the amount of supply to the moving grate in order to completely eliminate this raw burning, but the productivity of the moving grate is reduced.

In view of the above problems, the present invention provides a method of firing fine aggregate raw pellets as artificial fine aggregate without burning the fine aggregate raw pellets, and without reducing the productivity of the moving grate. It is intended to be provided.

[Means for Solving the Problems]

In order to achieve the above object, the firing method of the artificial fine aggregate of the present invention, a fine aggregate raw pellets having a particle size of 5 mm or less produced by granulating fly ash by a conventional method, and similarly granulating. The produced raw aggregate raw pellets are mixed or laminated in a predetermined ratio and supplied onto a moving grate for firing.

Further, it is desirable that the supply ratio of the fine aggregate raw pellets and the coarse aggregate raw pellets is adjusted to 0.03 to 0.10.

[Action]

Breathability is impaired because fine aggregate raw pellets with a particle size of 5 mm or less are mixed with coarse aggregate raw pellets (particle size (greater than 5 mm) at a predetermined ratio or laminated on the moving grate. In this way, the fine aggregate raw pellets can be fired without being burnt under the firing conditions of the coarse aggregate raw pellets, and the coarse aggregate raw pellets and the fine aggregate raw pellets can be fired at the same time.

Further, the supply ratio of the fine aggregate raw pellets and the coarse aggregate raw pellets to be supplied on the moving grate is preferably such that the air permeability is not impaired, and preferably the supply amount. It is better to adjust the ratio to 0.03 to 0.10.
The reason for this is that if the supply ratio is less than 0.03, fine aggregate (dust) from the coarse aggregate pellets is contained in the fine aggregate pellets after firing, resulting in fine aggregate pellets with a large amount of dust as a whole, which is not preferable. The productivity of aggregate pellets deteriorates. Further, if the supply ratio exceeds 0.10, the air permeability will be impaired, and firing defects such as raw burn and seizure will occur, leading to a reduction in production yield.

〔Example〕

 Examples of the present invention will be described below.

FIG. 1 is a schematic explanatory view showing a procedure of a method for firing an artificial fine aggregate according to the present invention, in which fly ash, pulverized coal, etc. quantitatively cut out from a raw material silo 1 for storing fly ash, pulverized coal, etc. The raw materials of No. 1 are charged into the mixer 2 and mixed.
After that, the mixed raw materials are transferred and put into the granulator 3, and water is added to granulate the fine aggregate raw pellets Ps having a particle diameter of 5 mm or less. Further, the raw materials mixed in the same manner are charged into the granulator 4, and water is added to granulate the coarse aggregate raw pellet Pl having a particle size of more than 5 mm. Fine aggregate raw pellets Ps granulated in this way
The crude aggregate raw pellets Pl and the coarse aggregate raw material Pl are introduced into the mixer 5 at a predetermined ratio and mixed, and then supplied from the supply unit A of the moving grate 6 onto the moving grate 6. At the time of this supply, a predetermined amount of floor covering P is supplied and laid on the moving grate 6 from the floor covering storage hopper 7 provided in the upper part of the supply section A. The raw pellets Ps, Pl thus stacked and supplied on the floor covering P on the moving grate 6 are conveyed toward the discharge section B, and in the course of this conveyance, preheating in the preheating furnace 8 Dried,
The unburned carbon is ignited in the subsequent ignition furnace 9, fired in the subsequent firing furnace 10, and finally cooled in the cooling zone 11. The pellets Pa after being conveyed to the discharge section B in this way are sieved by the sieving machine 12 into fine aggregate pellets Ps ′ having a grain diameter of 5 mm or less and coarse aggregate pellets Pl ′ having a grain diameter of more than 5 mm. Nao pellets Ps, Pl
In the lower part of the upper grate 6a of the moving grate 6 for transporting
A plurality of air boxes 13 are arranged along the carrying direction, and the lower small-diameter portion of the air boxes 13 is opened and connected to the exhaust duct 14 while avoiding the lower grate 6b. The inside of the exhaust duct 14 is exhausted by the blower 15, and due to the suction airflow, a suction airflow passing through from above to below is formed in the pellet layer. Therefore, the hot gas passing through the furnaces 8, 9 and 10 flows through the pellet layers, descends, and flows toward the wind box 13.

Example 1 According to the above-mentioned procedure, a raw material of fly ash having an ignition loss of 2.3 to 2.9% and a raw material of fine aggregate having a particle size of 5 mm or less and a particle size of 5 mm
While granulating super coarse aggregate raw pellets, this coarse aggregate raw pellet is mixed with fine aggregate raw pellets at a supply rate shown in the table below for the coarse aggregate raw pellet supply rate of 10 Ton / hr. Then, eight kinds of mixed raw pellets are manufactured, and these mixed raw pellets are moved to a moving grate at a moving speed of 1 m / min and a moving grate by using a firing facility having a moving grate width of 1.2 m. Firing was performed under the condition that the supply amount of floor / side bed pellets was 5 Ton / hr. This was followed by sieving to obtain fine aggregate pellets having a particle size of 5 mm or less.

The firing conditions of the obtained fine aggregate pellets are shown together in the following table.

In the above table, the No. 1 fine aggregate pellets contained a large amount of dust in the fine aggregate pellets and did not satisfy the particle size distribution specified in the JIS-A5002 standard. No.2 ~ No.5
As for the fine aggregate pellets, a good fired state satisfying the JIS-A5002 standard was obtained. Some of the fine aggregate pellets of No. 6 to No. 8 were partially burnt or seized, and did not satisfy the loss on ignition of 1% or less specified in the JIS-A5002 standard.

Example 2 Fine aggregates obtained by granulating fine aggregate raw pellets with a grain size of 5 mm or less and coarse aggregate raw pellets with a grain size of more than 5 mm, using fly ash with an ignition loss of 2.3 to 2.9% as a raw material The raw aggregate pellets and the coarse aggregate raw pellets are not mixed as shown in the above Example 1, but the fine aggregate raw pellets are supplied on the coarse aggregate raw pellets shown in the table of the above Example 1. The mixture was laminated in a quantitative ratio and supplied on a moving grate to obtain fine aggregate pellets having a particle size of 5 mm or less in the same manner as in Example 1 above.

When the firing state of the obtained fine aggregate pellets was investigated,
The results were exactly the same as those shown in the table of Example 1 above.

In addition, the above-mentioned laminated form is a form in which the fine aggregate raw pellets are thinly laminated on the entire upper surface of the coarse aggregate raw pellets, but a plurality of fine aggregate raw pellets are formed on the coarse aggregate raw pellets. Since the upper and lower surface communicating portions of the coarse aggregate raw pellets are formed in the form of forming a strip, or intermittently stacking in the supply direction, or a form of stacking these in a combined state,
This is preferable because the air permeability in the pellet layer is improved.

〔The invention's effect〕

As described above, according to the method for firing an artificial fine aggregate according to the present invention, the coarse aggregate raw pellets and the fine aggregate raw pellets are fired under the firing conditions of the coarse aggregate raw pellets to obtain the coarse aggregate pellets. And the fine aggregate pellets can be obtained at the same time, and the fine aggregate raw pellets can be fired without being burnt.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a procedure of a method for firing an artificial fine aggregate according to the present invention. 1 ... Raw material silo, 2 ... Mixer 3,4 ... Granulator, 5 ... Mixer 6 ... Moving grate, 6a ... Upper grate 6b ... Lower grate, 7 ... Floor Litter storage hopper 8 …… Preheating furnace, 9 …… Ignition furnace 10 …… Baking furnace, 11 …… Cooling zone 12 …… Sieving machine, 13 …… Wind box 14 …… Exhaust duct, 15 …… Blower A …… Supply section, B ... Discharge section P ... Floor covering Pa ... Pellets after firing Pl ... Coarse aggregate raw pellets Pl '... Coarse aggregate pellets Ps ... Fine aggregate raw pellets Ps' ... Fine Aggregate pellets

Claims (2)

[Claims] 1. A fine aggregate raw pellet having a particle size of 5 mm or less, which is produced by granulating fly ash by a conventional method, and a coarse aggregate raw pellet, which is similarly granulated and produced, are mixed at a predetermined ratio. ,
Alternatively, a method for firing an artificial fine aggregate is characterized in that the artificial fine aggregate is fired in a laminated state by supplying it onto a moving grate. 2. The supply ratio of the fine aggregate raw pellets and the coarse aggregate raw pellets is adjusted to 0.03 to 0.10. Method for firing artificial fine aggregate of.