Road arch wool soaking acid, deacidification (2)
Neutralizing water washing can remove residual acid from wool fibers and can further wash away carbonized plant impurities. Wool fibers have physically bound acids and chemically bound acids. Physically bound acids can be removed by washing with water. Chemically bound acids must be neutralized with alkali to remove them. The neutralization washing step includes water washing (washing of acid), neutralization, and washing (washing of alkali).
Washing acid is performed in the first tank on the neutralizer and is flushed with a large flow of clean water, which can both save the neutralization alkali and prevent the neutralization reaction heat from damaging the acid-containing wool. After the free acid has been rinsed and then neutralized by the second enthalpy, the commonly used neutralizing agent is soda ash, which neutralizes the chemically bound acid on the wool. The amount of soda ash is 3.5% of the weight of the wool, and the alkali liquor temperature is controlled at 38-40°C. Some of the finer wools absorb more acid. Under the above conditions, they will be insufficiently neutralized. If the increase in alkali content is detrimental to wool fibers, it may be necessary to add ammonia to the third tank to supplement the above-mentioned deficiency. Ammonia water can quickly seep inside the wool and further neutralize the combined acid of the wool. The bath temperature should be controlled at 35-37°C. Ammonia consumption is about 1.1%.
The salt and alkali contained on the fiber not only affect the feel but also cause alkali damage. Therefore, after neutralization, water washing is performed to wash away salts and alkalis remaining on the fiber. The pH of the cleaning tank is preferably neutral or somewhat acidic, and this tank is mostly live water, which can flow back into the first tank.
Dry-middle and washed wool is usually dried on a curtain dryer. The drying temperature is controlled at 6-70°C, while the coarse hair can be controlled at 70-75°C and dried to the required moisture regain. In order to reduce the wool output temperature to 25-30°C, the air volume can be increased in the last stage of the dryer to cool the wool.