JPH0230750B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for treating highly water-containing soil such as dredged soil, sludge, excavated soil, etc., which contain a large amount of water.
The purpose is to propose a method for disposing of sediment that is easy to transport and that can be easily disposed of in sediment processing plants such as dumping sites without damaging the environment. In general, sludge-like soil with a high water content is difficult to handle, and especially when transported using belt conveyors or dump trucks, problems such as scattering of soil and sand in the surrounding area reduce transport efficiency, worsen the working environment, and contaminate the road surface. is occurring. This invention was made in view of the above problems.
The gist of this is that resin powder, which has the property of swelling and gelling when it absorbs water, is mixed with sand and sand with a high water content, and the water in the sand and sand is absorbed, and the free water in the sand and sand is transported in a state where the free water content is reduced. This is a method for treating highly water-containing soil, which is characterized by adding salts or acidic electrolytes to the soil at a sand treatment plant to liberate water absorbed by the resin powder. The resin that absorbs water and swells used in this invention is one that does not dissolve in water but absorbs water and swells from several times to nearly 1,000 times its volume. Examples include starch-acrylonitrile or starch-methacrylate graft copolymers, partial hydrolysates of polyacrylonitrile and vinyl ester-ethylenically unsaturated carboxylic acid copolymers, polymers with hydrophilic groups such as sulfonated styrene, and polyethylene oxide. , polyvinyl alcohol, polyvinylpyrrolidone, sodium polyacrylate, polyacrylamide, carboxymethyl cellulose,
Radiation-irradiated products of water-soluble polymer compounds such as sodium polyacrylate, polyacrylamide copolymers, and bullulan, crosslinked products with crosslinking agents such as methylene bisacrylamide, dichloroacetic acid, epichlorohydrin, and aldehydes, and some of the hydrophilic groups Examples include those substituted with lipophilic groups and copolymers of isobutylene and maleic anhydride. When these resin powders are mixed with sand and sand having a high moisture content, the resin powder absorbs water and swells, reducing the amount of free water in the sand within a few minutes. Therefore, the handling of earth and sand is improved, and problems such as transportation workability, work environment, and road surface pollution can be improved. Resin powder usually has an average particle size of about 0.05 mm to 1.0 mm, and if the particle size is too large, it will be difficult to mix uniformly with the earth and sand, and it will take a long time to absorb water, which is undesirable. Sediment mixed with resin powder and granules to reduce free moisture and transported to a sand treatment plant such as a landfill or disposal site is added with electrolytes such as salts such as calcium chloride or acids with a low PH value. Normally, water absorbed by a water-absorbing resin is stable and does not easily evaporate or leach out, and remains in a water-absorbing and swollen state for a long period of time. However, when an electrolyte is added, the water-absorbing resin loses its water-absorbing ability and easily releases absorbed water. This free water evaporates and dries under the sun, or permeates into the ground and is taken into the natural circulation system. Example When treating 1 m ³ of sludge with water content W = 120% and wet density Pt = 1.4 g/cm ³ , resin powder (acrylic acid polymer product name: Aqua Keep) that has the property of absorbing water and swelling is used. 2 kg was added and mixed. After 2 to 3 minutes, the sludge becomes hard with a slump of about 0 to 5 cm, making it easy to transport by belt conveyor or dump truck, and problems such as workability, working environment, and road pollution can be improved. Furthermore, at the soil disposal site at the destination, an electrolyte aqueous solution consisting of calcium chloride was added to the soil to liberate absorbed water. Some of the free water was absorbed into the ground and some of it evaporated, leaving a solid with a low moisture content. A comparison with the conventional transportation cost of untreated sludge is shown in the table below.

[Table] The present invention is as described above, and this treatment method brings about the following effects. There is little risk of contaminating roads for transporting soil. Resin powder that has swollen by absorbing water will not remain in the disposal site for a long time and harm the environment. Transportation and handling efficiency is improved, and processing costs can be reduced.

Claims (1)

[Claims] 1. Mix resin powder that swells when it absorbs water with high-moisture content soil, absorb water in the soil, reduce free moisture in the soil, and then transport the soil.
A method for treating highly water-containing earth and sand, which comprises adding salts or acidic electrolytes at a sand treatment plant to liberate water absorbed by the resin powder.