JPS6018708B2 - Improver for heavy clay soil - Google Patents

Description

[Detailed Description of the Invention] Many of the cultivated lands in Japan are made of heavy clay soil, and not only is it extremely difficult to till the soil, but even if it is tilled, it may be damaged by rain or rain. The soil becomes sticky and hardened, making it almost impossible for water and air to circulate, severely inhibiting the growth of crops.

In addition, such areas have little value as arable land,
There are many places that are unexplored. Therefore, improving such soil into good arable land is a major challenge for Japanese agriculture. In view of the current situation, the present inventors have repeatedly investigated how to improve heavy clay soil, and as a result, red mud, which is produced in large quantities but has little use and is disposed of by dumping, is a cause of pollution. The present invention was completed based on the discovery that acid-treated grains exhibit excellent agglomeration effects.

That is, the present invention provides red mud with AI203 and Fe2 in red mud.
Add and mix one or more inorganic acids selected from hydrochloric acid, sulfuric acid, and phosphoric acid to the total amount of 03 at an acid distribution ratio of 100 to 190% to solubilize aluminum and iron in red mud. This article relates to an improvement agent for heavy clay soil.

The heavy clay soil that is the object of the present invention is soil containing 25% by weight or more of clay particles (0.002 side or less) according to the classification method of the International Society of Soil Science.

The residual red mud created during alumina production varies depending on the type of bauxite and the alumina extraction process, but normally the water content is 35 to 45%, and the dry matter composition is usually N2031.
8~25%, Si0210~20%, Fe20330~
42%, Na208-12%, Ti022-8%. The improver of the present invention is obtained by decomposing these with an inorganic acid such as sulfuric acid, hydrochloric acid, phosphoric acid, or nitric acid. Taking sulfuric acid as an example, the sulfuric acid concentration is preferably 50% or more, and the acetic acid rate is approximately equivalent to Na20, and 130 to 190% to the total amount of AI203 and Fe203 (hereinafter referred to as R203).
%, and if sulfuric acid is used within the above range, it is approximately 0.8~
After 2 hours of reaction, the R203 decomposition rate reaches 90% or more.
In addition, when using dilute 50-80% sulfuric acid, it is desirable to heat it.

Taking hydrochloric acid as an example, the acetic acid rate of hydrochloric acid is Na2
The decomposition rate reaches 90% or more in a reaction time of about 0.3 to 1 hour at approximately equivalent amount to R203 and 100 to 150% to R203. The present invention uses such a decomposed product as an improvement agent for heavy clay soil without filtration. However, when applying to heavy clay soil, the acid-treated red mud as it is is added to the soil and mixed. Alternatively, it may be used dry or diluted with water.

The amount used varies depending on the clay content, soil condition, and red mud composition, but it is preferably 0.5 to 5 tons of dry matter per melon (soil 10 rivers). The present invention will be further explained below with reference to Examples.

Example 1 Red mud with a water content of 37.2% (composition: 20320.
1%, Fe20339.2%, Na209.2%, Si
1.6k9 of 75% sulfuric acid was added to 1.6k9 of 75% sulfuric acid (0218.2%, Ti022.6%) and reacted for 70 minutes while boiling under low heat.

The yield was 2.45k9, and the decomposition rate of Yama 203 after the reaction was 9.
The decomposition rate of Fe203 was 92.4%.
This reaction product was air-dried in heavy clay soil (clay 42.4%, silt 42.6%, pongee sand 10.2%, coarse sand 4.8%).
for 11 minutes, and further added water to adjust the moisture content to 30%.
Result of measuring water resistant agglomeration rate after being left at room temperature for one week 23
．． It was 2%. On the other hand, for comparison, an aqueous solution of iron aluminum sulfate (AI2035
．． 52%, Fe20310.50%, SQ12.2%)
The water-resistant agglomeration rate was measured after adding water for 14 minutes and adjusting the water content to 30% by adding water for one week.
It was 2%.

In another comparative example, the above-mentioned red mud was added to the air-dried heavy clay soil LK9, water was added to adjust the water content to 30%, and the water-resistant agglomeration rate was measured after leaving it at room temperature for one week. 17.
It was 5%. <Water-resistant aggregate test method> Spread a thin layer of 20 yam on the paper laid on top of the sand layer.
The test soil was capillary moistened for 2 hours by pouring water to a depth of 0.5 degrees below the furnace paper.

Place this test soil in a Erlenmeyer flask containing 200 ml of water.
After being left for 24 hours and then shaken for 2 hours with a reciprocating shaker (100 times/min), it was shaken using a Yarder's sister device (knot flea 2.0, 1.0 0.f 0.2 f 0.1 Rib, amplitude 3.
8c and a shaking speed of 29 sub/min) for 25 minutes in water, the soil remaining on each tuna was combined, dried, and the weight (referred to as A) was measured. Next, after crushing this dried pulp lightly to the extent that the aggregates disintegrate, it is subjected to underwater moderation in the same way as above, the primary particles remaining on each section are combined, and after drying, the weight (B ) was measured, and the water-resistant agglomeration rate was determined from the following formula.

Water resistant agglomeration rate = rod table x loo (wt%) Example 2 3.1k9 of 25% hydrochloric acid was added to 1kg of the red mud of Example 1,
The mixture was reacted for 30 minutes under boiling water.

Claims (1)

[Claims] 1 In red mud, Al_2O_3 and Fe_2O_ in red mud
Add and mix one or more inorganic acids selected from hydrochloric acid, sulfuric acid, and phosphoric acid to the total amount of 3 at an acid distribution ratio of 100 to 190% to solubilize aluminum and iron in the red mud. An improvement agent for heavy clay soil.