Tungsten Wastewater Chemical Precipitation Zero Discharge

In the process of hydrometallurgy of tungsten, sodium tungstate solution is adsorbed by ion exchange resin, and the wastewater is discharged directly. Due to the limitations of the ion exchange process and the complexity of the raw materials, the WO₃ content in the wastewater after ion exchange is always maintained at a certain value, most of which are larger than 0.05g/l. This not only increases the cost of production and consumption of tungsten resources, but also increases the cost of environmental management.

Some scholars use chemical precipitation method to treat tungsten wastewater, which is simple in process, low in cost and high in metal recovery. It is an ideal method for treating tungsten waste water in tungsten smelting, including the following steps:

1.Pretreatment of tungsten containing wastewater after ion exchange is carried out.

2.Chemical precipitation of tungsten containing wastewater in pretreatment tungsten smelting is carried out.

In step 1, the concrete method of the pretreatment can be used to prepare the diluted sulfuric acid with concentrated sulfuric acid first to 150 ~ 200g/l, and to add dilute sulfuric acid into the waste water to be treated and reduce the pH value of the solution to less than 10.

In step 2, the specific method of chemical precipitation can be used as a precipitant in the pre treated tungsten waste water. After 2 to 4h, natural settlement is carried out. At this time, the WO₄^2- in the solution is converted into precipitation. The precipitate is collected by a filter press, and the analysis contains WO₃ in 30% to 50%, which can be used as a tungsten material and reinvest in the process.

The chemical precipitation method has a strong applicability, and can ensure that the WO₃ in the wastewater is almost completely precipitated on the premise that all the conditions are suitable, so that the amount of tungsten in the effluent is close to zero. In addition, the process is short and the amount of auxiliary materials consumed is less, which not only improves the WO₃ recovery rate of the process, but also reduces the pollution to the environment, and realizes the clean production process.

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