High Purity Ammonium Paratungstate Extraction from Tungsten Waste

Tungsten is an important national strategic resource as well as a non-renewable resource. The transition to a resource-saving and environment-friendly mode of development is also vigorously advocated and supported by the state in recent years. Therefore, the recovery of ammonium paratungstate from tungsten waste is nowadays many enterprises produce tungsten the main method of resources.

In order to effectively increase the yield of tungsten, reduce the processing flow and reduce the consumption, some scholars have proposed a method for producing high purity ammonium paratungstate from tungsten waste. The method includes the following production steps:

(1) Pre-collected tungsten waste through a rotary kiln at 750 ° C temperature air calcined 0.5 to 1.5 hours, the waste fired into waste tungsten oxide spare;

(2) The ammonia solution is pre-configured to control the ammonia concentration between 70 and 100g / L, the configured ammonia solution is added into a hot reaction kettle for standby; and the above-mentioned burnt waste tungsten oxide is added slowly to the reaction with stirring. The kettle is heated to react. The weight ratio of the ammonia solution to the waste tungsten oxide added is 1: 3~4, the temperature is controlled at 60~90 °C, and the ammonia concentration is monitored hourly to ensure the ammonia concentration is greater than 70 g / L. If concentration less than the required requirements, should be supplemented with concentrated ammonia, to be clarified when the basic solution for filtration, the filtrate standby;

(3) After the filtrate is cooled to 50 ° C, the ammonia concentration is preset to be between 50 and 65g / L, the mixture is further introduced into a hot reaction kettle, the mixture is stirred and steam is heated, the vapor pressure in the reaction vessel is controlled to 0.22-0.27MPa, The temperature is 80 ~ 100 ℃, the ammonia volatilization until the filtrate pH dropped to 7.5, Baume degree Be = 1 ~ 2, stop heating, reaching the desired end, cooled to 50 ℃;

(4) After cooling the filtrate was vacuum filtration for solid-liquid separation, obtained ammonium paratungstate crystals, drained with a mass percentage of 5% ammonium nitrate solution soaked, draw again to be bake, the ammonium paratungstate crystals in the infrared oven drying, obtained high purity ammonium paratungstate.

Compared with conventional waste treatment, the high-purity ammonium parotungstate prepared by the above method has high purity, good uniformity, normal distribution, complete crystal form, good chemical composition and excellent service performance. Moreover, the filter residue in the invention can be repeatedly used and purified, and the actual utilization rate of waste tungsten is close to 98%.

• < Prev
• Next >