Method for preparing ammonium paratungstate from sodium tungstate solution

A technology of ammonium paratungstate and sodium tungstate, applied in the field of producing ammonium paratungstate, can solve the problems of inappropriate comprehensive utilization or environmental protection, failure to recycle, etc., and achieve the effect of reduced workshop area, low emission and strong affinity

Inactive Publication Date: 2009-11-04
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In the strong alkaline anion exchange process, not only can it not be recycled, but also consume acid to neutralize it during post-handing liquid tre...

Method used

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  • Method for preparing ammonium paratungstate from sodium tungstate solution
  • Method for preparing ammonium paratungstate from sodium tungstate solution

Examples

Experimental program
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Embodiment 1

[0031] Crude Na obtained from the decomposition of tungsten mineral raw materials by NaOH 2 WO 4 Solution contains WO 3 147g / L, free NaOH50g / L, P 0.275g / L, As 0.3g / L, Si 0.7g / L, take 2L to concentrate and crystallize under boiling conditions to obtain Na 2 WO 4 Crystal 410g, which contains WO 3 65.5%, NaOH 2.1%. After the crystal water is dissolved, Na is obtained 2 WO 4 Solution contains WO 3 503g / L, free NaOH 16.1g / L, Si 0.09g / L, As 0.1g / L, P 0.1g / L. Crude Na 2 WO 4More than 95% of the P, As and 98% of the Si in the crystallization are in the alkali mother liquor after crystallization, and the alkali mother liquor contains 310g / L NaOH.

Embodiment 2

[0033] Crude Na as described in Example 1 2 WO 4 2L of solution is concentrated and crystallized under the condition of negative pressure of 50Kpa to obtain Na 2 WO 4 Crystal 425g, which contains WO 3 63.8%, NaOH 2.6%, the crystal dissolves into Na 2 WO 4 Solution contains WO 3 490g / L, NaOH 18.2g / L, Si 0.10g / L, As 0.11g / L, P 0.1g / L, crude Na 2 WO 4 About 95% of the P, As and more than 97% of the Si in the alkaline mother liquor, the alkaline mother liquor contains NaOH 300g / L.

Embodiment 3

[0035] Na as described in Example 1 2 WO 4 Na after dissolving crystal water 2 WO 4 Solution 0.5L contains WO 3 503g / L, add H 2 SO 4 Neutralize to a pH of about 6, make it and H 2 SO 4 The transformed macroporous weakly basic anion exchange resin D301 was used for ion exchange, and the post-delivery solution (post-adsorption solution) contained WO 3 0.02g / L. NH for loading tungsten resin 4 OH solution (containing NH 3 About 28%) desorption, may contain WO 3 208g / L(NH4) 2 WO 4 The solution is 1.20L, the latter is evaporated and crystallized to obtain APT. Under the condition that the crystallization rate is about 88%, APT contains impurities of less than 10×10 P, As, and Si by spectroscopic analysis. -6 , Sn is less than 1×10 -6 .

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Abstract

The invention provides a method for preparing pure ammonium paratungstate (APT) from crude Na2WO4 solution containing NaOH, P, As, Si, Sn and other impurities. The method comprises the following steps of crystallizing tungsten into Na2WO4 crystals through concentration, separating NaOH from impurities, redissolving and acidifying the Na2WO4 crystals till the pH of the crystals is between 2.0 and 6.0, adsorbing the crystals by use of macroporous weak alkaline anion exchange resin, desorbing the crystals by use of NH4OH, obtaining (NH4)2WO4 solution, performing evaporation crystallization and obtaining the APT. Under the condition that the crystallization rate is between 88 and 90 percent, the P, the As and the Si contained in the APT are all less than 10*10. The method has the outstanding advantage of small amount of discharged wastewater (mainly liquid after exchange), namely the volume of the discharged liquid after the exchange is one third to one twenty-fifth of that of liquid before the exchange; in addition, the discharged liquid after the exchange contains no detrimental impurities and is easy to control.

Description

Technical field [0001] The invention relates to the field of tungsten metallurgy and tungsten chemical industry, in particular to a method for preparing ammonium paratungstate (APT) from crude sodium tungstate solution. Background technique [0002] Ammonium paratungstate (APT) is an important intermediate product of tungsten metallurgy and tungsten chemical industry. To prepare ammonium paratungstate, the raw material is mainly the crude sodium tungstate solution obtained by treating tungsten raw materials (containing mineral raw materials and secondary raw materials), except for the Na 2 WO 4 In addition, it also contains excess NaOH and P, As, Si, Sn and other impurities. Therefore, in order to prepare ammonium paratungstate, two tasks should be completed: one is purification and impurity removal, and the other is transformation, that is, the conversion from sodium salt to ammonium salt. In order to accomplish the above tasks, the main processes at home and abroad are the stro...

Claims

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Application Information

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IPC IPC(8): C01G41/00
Inventor 赵中伟陈星宇李洪桂霍广生陈爱良
Owner CENT SOUTH UNIV
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