JP2586106B2 - Granular soil amendment and its production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a soil improvement material for effectively utilizing sewage remaining soil contained in aggregate washing sewage, and particularly to neutralization of acidic soil and ventilation of cultivated land. The present invention relates to a soil improvement material that can be improved and a method for treating aggregate washing wastewater by the method.

[Related Art] As for aggregates such as sand and gravel used in concrete, aggregates of rivers are depleted, and crushed stones are generally used. At crushed stone hills and sites, the topsoil on the crushed stone surface is washed with water before shipping. The sewage used for this washing is
It is prohibited by the River Pollution Control Law to release the water into the river as it is. Therefore, this wastewater is discharged through a sedimentation basin or sedimentation tank.

Also, there is a similar problem in a ready-mixed concrete factory, and sewage must be discharged in a similar manner.

Slaked lime, on the other hand, is commonly used as a neutralizing agent for acidified arable land.

The sediment of such sewage treatment is difficult to handle, is dried in the sun, reduces the moisture content of the soil, and is then dumped as industrial waste in a landfill or the like. In addition, slaked lime is in a powdery form, so that it is necessary to take great care in handling such that the lime easily jumps into the eyes and the like when sprayed.

[Problems to be Solved by the Invention] Accordingly, the present invention is an inexpensive, safe and industrial method for studying the sedimentation speed when sedimentation of sewage discharged from quarries, ready-mixed concrete factories, etc. in sedimentation ponds and sedimentation tanks The present invention has found a sewage treatment method that is also advantageous in terms of terms, and at the same time, has found a way to use the sewage residual soil cake obtained by this sewage treatment method as a soil conditioner. Therefore, an object of the present invention is to economically treat sewage discharged from quarries and ready-mixed concrete factories, and at the same time to provide an inexpensive, safe and industrially advantageous soil conditioner.

[Means for Solving the Problems] The gist of the present invention is to add slaked lime to aggregate washing sewage to form a sewage residual soil cake, add a cement-based solidifying material to the cake, mix and granulate the cake. It is a granular soil improver that has been made. Then, slaked lime is added to the aggregate washing sewage, a sewage remaining soil cake is made, a cement-based solidifying agent is added to the cake, mixed, and granulated to produce a granular soil improving material. This is a method for producing an improved material.

Slaked lime or quick lime is sprinkled and mixed with sewage in which filth such as topsoil adhered to quarries is suspended, and after standing still, the supernatant is removed to obtain a hydrated sewage remaining soil cake. Next, this cake is transferred to a pelletizer and granulated while spraying a cement-based solidifying material, whereby a granular soil conditioner is formed. The granulation method here is not particularly limited, and granulation can be performed by a known method, and can also be performed by extrusion molding.
The size of the particles at this time is preferably about 2 to 10 mm.

In addition, a granular soil improver can be produced by mixing a chemical fertilizer or the like during the granulation process. It is also preferable to mix a municipal sewage sludge other than the sewage residual soil to produce a granular soil conditioner.

The hydraulic hardening material used in the present invention is not particularly limited, and a commercially available cement-based hardening material can be used.The amount of the hardening material is determined in consideration of the soil contained in the sewage cake and its properties. Decide. However, other fertilizer components can be included, taking into account the properties of the cake or the properties of the desired soil conditioner.

As the pelletizer, a well-known pelletizer can be used, and it is not particularly limited, but a pelletizer having a diameter of 2 to 10 mmФ is preferable.

[Action] In the process of preparing the granular soil conditioner of the present invention, although the reason is not clear, by adding slaked lime, an action like a sedimentation agent due to alkalinity is performed, and solid-liquid separation can be performed in a short time. The surface of the particles of the remaining soil is covered with slaked lime, and the slaked lime is eluted in the acidic soil to neutralize the soil. That is, by adding the solidifying material to the residual soil cake obtained from the washing wastewater of the quarry, the moisture attached to the cake undergoes a hydration reaction with the solidifying material, resulting in dehydration,
Dry, granulate and harden it. The granulated and granulated soil conditioner can improve the water retention, water permeability, and air permeability of the soil when sprayed and mixed.

Next, the granular soil improver of the present invention and a method for producing the same,
Although a specific example will be described, the present invention is not limited to the following example.

In sewage EXAMPLES fresh concrete factory, the suspension 1 m ³ which contained a solid content of about 2 wt%, 1 wt% of hydrated lime on the solid content
After addition, mixing, stirring and standing, the supernatant water was removed to obtain a sewage residual soil cake having a water content of 60%.

This cake was transferred to a pelletizer with a diameter of 1 m, and about 5 to 10 mm in diameter was added while adding about 5% by weight of a cement diameter solidifying material.
The pellet was granulated into mm pellets to obtain a soil conditioner.

The pressure fracture strength of this granulated pellet is 5 to 10
kg / cm ² .

Moreover, when this granular soil improver is applied to a field, the permeability of the soil is increased, and as shown in the following cultivation results, it is proved that the soil improver is a good soil improver.

Spinach seeds were sown in a vegetable garden where 300 to 400 g of the soil conditioner was sprayed per 1 m ^{2 of} vegetable garden and in a vegetable garden where no soil spray was applied. After sowing the seeds of spinach, all the gardens germinated 3 to 4 days later, but the spinach in the vegetable garden that did not scatter was not found. Was. In the sprayed vegetable garden, they grew well and were harvested after about 35 days.

[Effects of the Invention] The soil conditioner of the present invention firstly enables industrial waste to be easily and inexpensively used as a soil conditioner, and secondly, acid soil. To provide a new soil conditioner that can improve soil water retention, water permeability, and air permeability by modifying and granulating soil. Third, it also provides a method that can simultaneously solve sewage problems in quarries and the like economically. Technical effects such as doing were obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication // C09K 101: 00

Claims (2)

(57) [Claims] A granular soil improver obtained by adding slaked lime to aggregate washing wastewater to form a sewage residual soil cake, adding a cement-based solidifying material to the cake, and granulating the cake. 2. A method of adding slaked lime to aggregate washing sewage to form a sewage remaining soil cake, adding a cement-based solidifying material to the cake, mixing and granulating the cake to produce a granular soil improvement material. Method for producing granular soil conditioners.