Sodium Tungstate Solution Purification -- Magnesium Carbonate Method
- Details
- Category: Tungsten Information
- Published on Tuesday, 22 August 2017 11:25
Sodium tungstate is an important chemical raw material and an important intermediate product in tungsten metallurgy production.
In recent years, the flotation technology of scheelite is more and more mature, but the sodium tungstate solution produced will need to be purified.
In general, the main impurities in crude scheelite tungstate solution is phosphorus, fluorine, arsenic, tin, molybdenum, silicon, arsenic and other impurities. The removal of phosphorus, arsenic, silicon and fluorine by conventional magnesium salt precipitation is the removal of impurity ions by soluble magnesium salts such as MgCl2 and MgSO4, and the purification effect is better. However, magnesium salt precipitation method also has a drawback, that is, Cl2, SO4 and other anions are easy to cause resin adsorption capacity decline, after using this method, it is not suitable to use ion exchange method, and ion exchange method has a large fan base in our China. Therefore, some scholars have suggested that the alkaline magnesium carbonate with very low solubility can be used to purify sodium tungstate solution with high impurities. Then, is this method feasible?
The basic magnesium carbonate, concentrated sulfuric acid, sodium hydroxide and sulfuric acid were adopted in the test, and a certain amount of sodium tungstate solution was obtained by the dissolution of sodium phosphate from white tungsten ore, adding tungstic acid powder to it, adjusting pH to 8~12, and filtering insoluble matter. Take 100 mL to adjust the pH of the sodium tungstate solution in a conical flask. A certain amount of basic magnesium carbonate powder is added to the decomposition solution. The conical bottle is placed in a constant temperature water bath, and the reaction temperature is 50~100 °C, and the reaction time is 30~180 min. At the end of the reaction, the purified sodium tungstate solution and the impurity residue are obtained by filtration.
After testing the purified sodium tungstate solution and miscellaneous slag, the scholars concluded that the sodium tungstate solution purified by the basic magnesium carbonate can effectively remove phosphorus, fluorine, arsenic and silicon, the removal rate of fluorine, phosphorus and silicon was 95% and the removal rate of arsenic reached 36.19%. The indexes were close to or reached the level of purification by the classical magnesium salt precipitation method. At the same time, fluorine in sodium tungstate solution reacts with basic magnesium carbonate to form NaMgF3. Phosphorus, arsenic and silicon react to form Mg3(PO4)2, Mg3 (AsO4)2, MgSiO3, which have small solubility products. When the impurity content reaches the requirement of the subsequent process, the effect on the ion exchange resin is low, and the purification of the ion exchange method is almost perfect.
In fact, purification of sodium tungstate solution is feasible with magnesium carbonate method, when the feasibility of the magnesium carbonate purification process has been proved, it also means that the enterprise has a choice in the process design.
- Tungsten Oxide Manufacturer & Supplier, Chinatungsten Online: www.tungsten-oxide.com
- Tungsten News & Prices of China Tungsten Industry Association: www.ctia.com.cn
- Molybdenum News & Price: news.molybdenum.com.cn
- Tel.: 86 592 5129696; Fax: 86 592 5129797; Email: sales@chinatungsten.com
sales@chinatungsten.com
闽公网安备 35020602000140号