Method for preparing sodium stannate using circuit board tin-stripping wastewater

The invention relates to a method for preparing sodium stannate by utilizing tin-stripping wastewater of a circuit board. Collected tin-stripping wastewater is neutralized and precipitated by adding alkali to obtain tin sludge with higher tin content; the tin sludge is beat by adding the alkali, and is subjected to high-temperature roasting and countercurrent leaching; then a leachate is subjected to filter pressing; a filtrate is subjected to evaporation, concentration and centrifugal separation after impurity removal; and 10 to 15 percent sodium hydroxide solution is used to wash the obtained product, and thus a crude sodium stannate product can be obtained and then is vacuum dried at a temperature of between 100 and 110 DEG C for 2 to 3.0 hours to obtain a sodium stannate product. The method ensures that the separation rate of tin in the tin-stripping wastewater can reach more than 99 percent, finds a novel treatment way for the tin-stripping wastewater which is produced by printed circuit board industry and is extremely difficult to treat, gives a reasonable fate for all pollutants in the tin-stripping wastewater, and realizes the resource utilization of useful components of the tin-stripping wastewater to the utmost extent when realizing the innoxious treatment of the tin-stripping wastewater.