Low-bath-ratio two-bath-method bleaching technology

The invention relates to a low-bath-ratio two-bath-method bleaching technology. The low-bath-ratio two-bath-method bleaching technology comprises pretreatment, whitening and dyeing, and after-treatment, and is characterized in that pretreatment refers to pretreatment on a yarn after loose yarn spinning and before dyeing and comprises the following steps: water enters a main cylinder and flows backinto an auxiliary cylinder, dissolved salt is added into the main cylinder and then flows back into the auxiliary cylinder, caustic soda is added into the main cylinder at the proportion of 2-4 g/L,clear water enters the auxiliary cylinder, hydrogen peroxide is directly added into the main cylinder at the proportion of 6-12 g/L, the temperature is increased, waste water is discharged, washing isperformed for 10-15 min, liquid waste is discharged, and neutralization is conducted. A low-bath-ratio high-temperature and high-pressure cheese dyeing machine is utilized, the circulation mode is single circulation, the dyein