JPH0742149B2 - Method of firing artificial fine aggregate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for firing artificial fine aggregates, and in particular, to firing artificial fine aggregates having a particle size of 5 mm or less, which are used as aggregates of artificial sand or concrete. Regarding the 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 firing the fine aggregate raw pellets, the fine aggregate raw pellets are manufactured by adding and mixing the raw pellets that have already been fired with the same particle size as the raw pellets. is there.

[Problems to be Solved by the Invention]

However, in the method disclosed in the above-mentioned JP-A-59-39758, although it has various uses because only the fine aggregate is fired, it is a mixture with the fired fine aggregate pellets and the particle size is small. Therefore, the ventilation in the layer of pellets has not been completely improved, and there remains a problem that raw fine aggregate pellets are 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, fine aggregate raw pellets having a particle size of 5 mm or less produced by granulating fly ash by a conventional method, and a burned coarse aggregate pellet And are mixed in a predetermined ratio, or in a laminated state and supplied on a moving grate for firing, and the supply ratio of the fine aggregate raw pellets and the baked coarse aggregate pellets is the supply ratio. It is desirable to adjust to 0.03-0.10.

[Action]

Fine aggregate with a particle size of 5 mm or less is mixed with burned coarse aggregate pellets (particle size over 5 mm) at a predetermined ratio, or is laminated and supplied onto a moving grate so that ventilation is good and fine aggregate is possible. In addition to firing raw pellets without burning them,
By using semi-finished calcined coarse aggregate pellets that did not satisfy the ignition loss 1% or less defined in JIS-A5002 as the calcined coarse aggregate pellets, semi-finished calcined coarse aggregate pellets It can be fired at the same time as the re-firing.

Further, the supply ratio of the fine aggregate raw pellets and the calcined coarse aggregate pellets to be supplied onto the moving grate should be such that the air permeability is not impaired, and it is preferable to supply them. It is recommended to adjust the quantity 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. The granulated fine aggregate raw pellets Ps and the fired coarse aggregate pellet storage hopper 4 are charged into the mixer 5 at a predetermined ratio with the fired coarse aggregate pellets Pl having a particle size of more than 5 mm. Then, after mixing, it is supplied onto the moving grate 6 from the supply section A of 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 mixed 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 is carried out. After being dried, the unburned carbon is ignited in the subsequent firing furnace 9 and then in the subsequent firing furnace 10.
And is 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. Mixed pellet P
Below the upper grate 6a of the moving grate 6 for carrying s, Pl, etc., a plurality of wind boxes 13 are arranged along the carrying direction,
The lower small-diameter portion of the wind box 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 In the manner described above, fine aggregate raw pellets with a particle size of 5 mm or less, which were made from fly ash with a loss on ignition of 2.3 to 2.9% as a raw material, were granulated, and the pelletized fine aggregate raw pellets were strengthened. Eight types of mixed pellets are manufactured by mixing semi-finished calcined coarse aggregate pellets that did not satisfy a heat loss of 1% or less with the supply rate shown in the table below for this coarse aggregate pellet supply rate of 10 Ton / hr. Then, using a mixing facility with a moving grate width of 1.2 m, these mixed pellets were moved at a moving speed of 1 m / min and the floor / side-laying pellet supply rate on the moving grate was 5 Ton / hr. It baked on the basis of the conditions of. 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 defined 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. Incidentally, the semi-finished fired coarse aggregate pellets had a loss on ignition of 1% or less for each No. and satisfied the JIS-A5002 standard.

Example 2 Granules of fine aggregate raw pellets having a particle size of 5 mm or less, which were made from fly ash having a loss on ignition of 2.3 to 2.9%, were filled, and the obtained raw pellets of fine aggregate and a loss on ignition of 1% or less were satisfied. Without the semi-finished calcined coarse aggregate pellets which were not mixed as shown in the above Example 1, the fine aggregate raw pellets were put on the calcined coarse aggregate pellets in the table of the above Example 1. The pellets were laminated at the feed rate shown and fed onto the moving grate to obtain fine aggregate pellets having a particle size of 5 mm or less in the same manner as in Example 1.

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 laminated form, on the coarse aggregate pellets that have been fired
Although the fine aggregate raw pellets were thinly laminated on the entire upper surface, a plurality of fine aggregate raw pellets were laminated on the baked coarse aggregate pellets, or intermittently laminated in the supply direction,
Alternatively, a form in which these are combined in a laminated state is preferable because the upper and lower surface communicating portions by the fired coarse aggregate pellets are formed, and the air permeability in the pellet layer is better.

〔The invention's effect〕

As described above, according to the method for firing the artificial fine aggregate according to the present invention, the fine aggregate raw pellets can be fired without being burnt, and as the fired coarse aggregate pellets, JIS-A500.
By using the semi-finished calcined coarse aggregate pellets that do not satisfy the loss on ignition of 1% or less defined in the standard 2, the semi-finished calcined coarse aggregate pellets can be re-sintered at the same time.

[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 ... Granulator 4 ... Calcined coarse aggregate pellet storage hopper 5 ... Mixer, 6 ... Moving grate 6a ... Upper grate, 6b ... Lower grate 7 …… Floor material 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 part, B …… Discharge part P …… Bedding material Pa …… Pellets after firing Pl …… Piece of coarse aggregate pellets Pl´ …… Pellet of coarse aggregate 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 produced by granulating fly ash by a conventional method and a calcined coarse aggregate pellet are mixed at a predetermined ratio or moved in a laminated state. A method for firing an artificial fine aggregate, which comprises feeding the fire onto a grate and firing. 2. The supply ratio of the fine aggregate raw pellets and the calcined coarse aggregate pellets is 0.03 to 0 in terms of the supply amount (weight / hour) ratio.
The method for calcination of artificial fine aggregate according to claim 1, characterized in that it is adjusted to 10.