Low-temperature crystallization method of ammonium polyvanadate

Abstract

The invention discloses a low-temperature crystallization method of ammonium polyvanadate. The low-temperature crystallization method includes following steps: (1) adding a crystallization initiator to vanadium liquid and stirring the vanadium liquid to dissolve the crystallization initiator; (2) adding acid to regulate the pH of the vanadium liquid to 1.0-7.0; and (3) continuously stirring the vanadium liquid to precipitate-out ammonium polyvanadate crystal, and performing filtration to obtain the ammonium polyvanadate crystal. The crystallization initiator is a mixture composed of one or more from water-soluble organic amine compounds and derivatives thereof. The method can effectively achieve high-concentration vanadium precipitation, can reduce the production amount of vanadium precipitation waste water by many times, can crystallize the ammonium polyvanadate crystal at room temperature, can effectively reduce energy consumption of steam and the like, can reduce the clean production cost and can increase yield rate. In the invention, the ammonium polyvanadate is precipitated-out in the form of a large-granular crystal being complete in structure. The method can reduce the entrainment of harmful impurities such as NH4<+>, Na<+>, K<+>, Fe<3+>, SO4<2->, SiO3<2-> and the like and can improve product quality.

Description

Technical field [0001] The invention relates to a method for sinking vanadium, in particular to a method for low-temperature crystallization of ammonium polyvanadate. Background technique [0002] Industrially, the process of producing vanadium oxides (including vanadium trioxide, vanadium pentoxide, etc.) using vanadium-containing materials such as vanadium-titanium magnetite, vanadium slag, stone coal, and waste catalysts as raw materials includes the following main steps: [0003] (1) Activation: the vanadium element in the solid-phase raw material is converted into soluble vanadate or vanadic acid through the roasting or acidification process; [0004] (2) Leaching: leaching soluble vanadate to liquid phase from acid, neutral or alkaline aqueous solution; [0005] (3) Precipitation of vanadium (crystallization): the vanadium leaching solution is obtained after purification and impurity removal, and precipitation reagents are added to convert the vanadate into insoluble matter and ...

AI Technical Summary

Problems solved by technology

[0013] (1) The vanadium precipitation process is always kept between 80 and 100 °C, which requires a large amount of steam consumption and high energy consumption costs

[0014] (2) The high-temperature vanadium precipitation process usually requires that the concentration of vanadium in the vanadium liquid be ≤30g / L (the ammonium polyvanadate produced due to high vanadium concentration is amorphous, loose in structure, and prone to soluble NH 4 + 、Na + 、K + , Fe 3+ , SO 4 2- , SiO 3 2- and other harmful impurities, which are difficult to remove, and the product qualification rate), which makes a large amount of high-salt and high-ammonia nitrogen wastewater produced by the precipitation of vanadium

[0015] (3) Due to the direct heating of steam, the steam condenses in the liquid phase, which dilutes the concentration of vanadium in the liquid phase, which will inevitably lead to an increase in the output of vanadium precipitation wastewater and increase the pressure of subsequent wastewater treatment

[0016] (4) The process parameters are demanding, and the secondary acid addition must be strictly controlled between pH = 1.8 to 2.5. Slight fluctuations will easily cause "sticky material" and "bad material" phenomenon

[0017] (5) It takes a long time to deposit vanadium, and the residual vanadium in the liquid after heating up to vanadium deposition is ≤0.2g / L. Industrial production usually needs to react for more than 3 hours, which greatly restricts the improvement of production efficiency

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