JPS5854177B2 - Method of manufacturing pellets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a caking agent used in pellet granulation, and an object of the present invention is to reduce the cost of pellet production. The goal is to effectively utilize sludge and prevent secondary pollution.

Normally, pellets are produced by adding a binder such as bentonite to fine ore.

However, the high cost of bentonite and the need for a grinder to reduce the ore to a fine powder make pellets very expensive.

On the other hand, methods for treating surplus sludge in activated sludge treatment include, after dehydration, incinerating it together with other waste, burying it in the soil, or using it as fertilizer after drying.

However, in the current dehydration treatment technology, the water content is at a dehydration limit of about 80 to 85.

For this reason, incineration treatment has serious drawbacks such as high fuel consumption and bad odor.

In addition to the problem of putrid odor when the waste is buried in the ground, there is also the problem that toxic substances from treated wastewater are absorbed into the sludge and leached back into the soil.

Furthermore, if the sludge is to be used as fertilizer after drying, the moisture content is high and the sludge forms flocs, making drying techniques difficult and producing a foul odor during drying.

Furthermore, some treated wastewater cannot necessarily be used as fertilizer.

The present invention aims to reduce the cost of the above-mentioned pellets, and to effectively utilize the surplus sludge generated when treating activated sludge to prevent the occurrence of secondary pollution.
The gist thereof is a method for producing pellets, which is characterized in that surplus sludge generated during activated sludge treatment of wastewater containing organic matter is added to a raw material for pelletizing and granulated.

Surplus sludge from activated sludge treatment plants is free from organic matter, and generally has a high moisture content and is extremely viscous, so even if activated sludge is added to the ore while it remains coarse, it will not be granulated. It has been found that it is possible to produce green pellets with sufficient strength.

This is thought to be due to the coagulation effect of the corrosive acid in the excess sludge.

Regarding the blending ratio of excess sludge to the granulation raw material, increasing the amount added increases the caking property and the strength as raw pellets, but the component elements of excess sludge are approximately 50% carbon and approximately 50% hydrogen. 50, and when charged into a reduction furnace such as a blast furnace, the crushing strength and pulverization rate decrease.

Moreover, if the amount is too small, caking properties will not be exhibited and the strength as pellets will be poor.

From the above, the blending ratio in the method of the present invention is preferably 1 to 5.

Pellets granulated by the method of the present invention can be used as general oxidized pellets, reduced pellets, cold pellets, etc. Since activated sludge is an organic substance, especially when added to cold pellets, the high temperature properties of cold pellets can be improved. It is also useful.

Examples are listed below along with comparative examples.

When carbonizing coal, condensed water (hereinafter referred to as ammonium water) is generated.

Surplus sludge generated when this is treated with activated sludge and food processing wastewater is treated with activated sludge to remove insects (the elemental analysis values of the surplus sludge at this time are shown in Table 1).

The moisture content at this time was 83 饱.

) was added to hemaquite ore and magnetite ore, which are raw materials for pellet granulation, with the particle size shown in Table 2, and serpentinite and limestone were added as ingredient adjustments to granulate the mixture.Table 2 shows the results of granulation.

As is clear from Table 2, in order to obtain green pellets with sufficiently high strength in the conventional technology, it is necessary to make the powder into a sufficiently fine powder and add a binder such as bentonite, whereas with the method of the present invention, pellets with sufficiently high strength can be obtained even though they are coarse grains. is obtained.

As detailed above, according to the method of the present invention, surplus sludge generated when treating activated sludge is used as a binder for the pellets, thereby reducing the cost of the pellets and making effective use of the surplus sludge. This is a valuable invention that can prevent secondary pollution from occurring.

Claims (1)

[Claims] 1. A method for producing pellets, which comprises adding excess sludge generated during activated sludge treatment of wastewater containing organic matter to a raw material for pellet granulation.