CN100348751C - Treatment method of high alkali concentration sodium tungstate solution - Google Patents

Abstract

The present invention relates to hydrometallurgy, particularly to a process for processing a highly basic concentration sodium tungstate solution by an ion-exchange method. Strongly basic anion-exchange resin is used, the saturated resin is desorbed when the highly basic concentration solution is processed, and a plurality of exchange columns are connected in series for column stringing operation or a solid moving-bed is used for adsorption; by using the characteristic that the concentration of a NaCl solution in exchanged liquid is rapidly reduced along with the enhancement of the NaOH concentration, the base concentration of a high concentration NaOH solution is further enhanced through evaporation and concentration, and NaCl in the solution can be separated so that superfluous free base can return to a tungsten ore leaching procedure. The production cost is reduced, and the present invention is also good for environment protection.

Description

Treatment method of high alkali concentration sodium tungstate solution

Technical field:

The invention relates to hydrometallurgy, a process for treating sodium tungstate solution with high alkali concentration by ion exchange method.

Background technique:

The ion exchange method in tungsten hydrometallurgy uses strong basic anion exchange resin to exchange reaction with basic crude Na ₂ WO ₄ solution to adsorb tungsten, and leave most impurities such as phosphorus, arsenic, silicon, etc. in the post-transaction liquid Drain, and then desorb with a mixed solution of NH ₄ Cl and NH ₄ OH to obtain a pure (NH ₄ ) ₂ WO ₄ solution. Compared with the original classic method, this method has a short process, can complete the two tasks of impurity reduction and transformation at the same time, and has simple equipment and high tungsten recovery rate, so it has been widely used in tungsten metallurgical enterprises.

But the ion exchange method can only deal with the feed liquid with low alkali concentration. For the sodium tungstate solution containing WO ₃ 15-25g/l, when the NaOH concentration is greater than 10g/l, the exchange capacity of tungsten will be significantly affected. It has actually been found in production practice that NaOH in the solution has adverse effects above about 4 g/l.

However, with the gradual consumption of high-quality black tungsten resources, people have to turn to high-calcium wolframite concentrate, scheelite or even low-grade complex tungsten mineral raw materials. When the mineral contains high calcium, due to thermodynamic reasons, a larger amount of NaOH must be used (scheelite is generally more than 2.5 times the theoretical stoichiometric amount, and low-grade ore is even higher). In this way, the remaining alkali amount in the obtained leaching solution is too high and seriously affects the subsequent ion exchange, resulting in a rapid decline in the working exchange capacity of the resin.

At the same time, because the high alkali solution contains a large amount of free alkali, which is diluted to a low concentration according to the traditional process, the alkali cannot be recovered after adsorption, and it can only be discharged in vain, polluting the environment.

Invention content:

The purpose of the present invention is to address this problem, to provide a process for ion exchange adsorption under high alkali concentration conditions, to achieve high alkali and high tungsten concentration (NaOH 20 ~ 51.3g/l, WO ₃ 10 ~ 200g/l) conditions Under the ion exchange, the solution with high alkali concentration can be directly adsorbed, and the exchanged solution can be economically concentrated and returned to the leaching process.

The scheme of the present invention is: use strongly basic anion exchange resin, when dealing with high alkali concentration solution, only carry out desorption to already saturated resin.

① Use multiple fixed-bed exchange columns in series to carry out column stringing operation: after the A exchange column leaks through, the tungsten-containing exchanged liquid flows directly into the B exchange column and continues to adsorb; after the B column leaks through, it is further connected into the C column; After the column leaks through, it is further inserted into the D column; it is pushed downstream in turn; after the A column reaches saturation, the tungsten is desorbed and the resin is regenerated at the same time, and the regenerated A column is connected to the most downstream; this is done alternately, and the cycle works.

When stringing columns, if the linear velocity of the solution is below 0.1cm/min, it is advisable to operate in countercurrent (solution from bottom to top); if the linear velocity of the solution is above 0.1cm/min, either downstream or countercurrent operation is acceptable.

For the fixed-bed ion-exchange columns currently used in industry, since the entire column is actually required to be desorbed together during operation, the exchange zone can only be "pushed" out of the column to be desorbed, so several identical exchange columns are connected in series downstream and upstream Continue to exchange after the column leaks through, and gradually move the exchange zone to the downstream column until the upstream column is saturated, and then desorb separately.

②Using dense moving bed adsorption: feed liquid enters continuously from the lower part of the column, flows out from the top of the resin bed, and saturated resin is discharged continuously or in batches from the bottom; at the same time, the same regenerated resin is replenished continuously or in batches at the top; desorption regeneration of saturated resin It is carried out in a small ion exchange column, and only the saturated part is taken out for desorption.

Advantage of the present invention and remarkable effect fully embody in:

The main components of post-delivery solution are NaOH and NaCl solution. The characteristic of this mixed solution is that the concentration of NaCl solution decreases rapidly with the increase of NaOH concentration. Utilizing this feature, the high-concentration NaOH solution is concentrated by evaporation. On the one hand, the alkali concentration is further increased. On the other hand, the NaCl in the solution can be separated, so that the excess free alkali can be returned to the tungsten ore leaching process, which reduces the production cost. Conducive to environmental protection.

Detailed ways:

The present invention will be further illustrated below by specific examples.

Example 1 Decomposition of scheelite concentrate (WO ₃ grade is 64.5%, the amount of NaOH is 2.5 times the theoretical amount, the decomposition temperature is 160°C, the holding time is 4.5 hours, and the decomposition rate is 97.45%). The resulting liquid contains NaOH51.3g/l, WO ₃ 97.8g/l; use two Φ200×1400mm exchange columns in series for adsorption operation, from top to bottom for downstream adsorption, and connect to the second column after the first column leaks through. After the second column leaked through, it was connected to the third column, and after the third column leaked through, the first column was desorbed separately. The working capacity of the first column was analyzed to be 125 mg WO ₃ /ml wet resin. After handover liquid NaOH 47.7g/l, NaCl 24.0g/l. Evaporate the post-transfer liquid to a NaOH concentration of about 250g/l, then add solid NaOH to a concentration of more than 500g/l, cool to about 30°C and place it for 4 hours; after NaCl is completely crystallized from the solution, centrifuge to obtain a small amount of NaCl (less than 45g/l) NaOH concentrated solution; the recovered NaOH is returned to the tungsten ore leaching operation, and the scheelite concentrate is decomposed under the same conditions, and the decomposition rate is 97.17%.

Example 2 Decomposition of high-calcium black tungsten medium ore (containing 12.8% of tungsten, 43.4% of WO ₃ grade, 3.5 times of the theoretical amount of NaOH, decomposition temperature of 160°C, holding time of 4.0 hours, decomposition rate of 98.45%) obtained material The liquid contains NaOH 49.2g/l, WO ₃ 58.1g/l; two Φ200×1400mm exchange columns are used for series adsorption operation, countercurrent adsorption from bottom to top, and the second column is connected after the first column leaks through; analysis A working capacity of 117 mgWo3/ml wet resin was obtained. After delivery, the liquid was evaporated to 1000g/l, cooled and placed for 8 hours, and the NaCl crystals were separated by centrifugation; the obtained concentrated NaOH solution was returned to the leaching ingredients.

Example 3 The feed liquid contains WO ₃ 25g/l, NaOH 20g/l, the exchange column is Φ16×36mm, 4 columns are connected in series and exchanged in parallel; after the upstream column is saturated, the working capacity is 128mg WO ₃ /ml wet resin.

Example 4 The inner diameter of the dense moving bed is 80mm, the height of the resin bed is 2000mm, and the feed liquid containing NaOH 51.2g/l and WO3 49.3g/l flows through the exchange column from bottom to top; Take out the resin with a height of 300mm from the lower end of the column, and at the same time replenish the same amount of regenerated resin at the upper end to continue the exchange adsorption. The saturated resin taken out was loaded into a column with an inner diameter of 60 mm and desorbed with ammonia/ammonium chloride solution to obtain an exchange capacity of 122 mg WO ₃ /ml wet resin.

Claims (6)

1. The treatment method of high alkali sodium tungstate solution with NaOH concentration of 20-51.3g/l uses strong basic anion exchange resin. When dealing with high alkali concentration solution, only the saturated resin is desorbed, and multiple Fixed exchange columns are connected in series for column stringing operation: after the A exchange column leaks through, the tungsten-containing exchanged liquid flows directly into the B column and continues to adsorb; after the B column leaks, it is further connected into the C column; after the C column leaks through, it is further serialized into the D column; advance downstream in turn; after the A column reaches saturation, desorb the tungsten and regenerate the resin at the same time, and the regenerated A column is connected to the most downstream; so alternately, cycle operation, when the column is connected, if the linear velocity of the solution is at If the linear velocity of the solution is below 0.1cm/min, operate in a downstream or countercurrent manner, connect several identical exchange columns in series downstream, continue to exchange after the upstream column leaks through, and gradually The exchange zone is moved to the downstream column until the upstream column is saturated, and then desorbed separately. 2 The treatment method of the high alkali concentration sodium tungstate solution whose NaOH concentration is 20-51.3g/l uses a strong basic anion exchange resin, and only desorbs the saturated resin when dealing with the high alkali concentration solution. : Using dense moving bed adsorption, the feed liquid enters continuously from the lower part of the column, flows out from the top of the resin bed, and the saturated resin is released continuously or in batches from the bottom; at the same time, the same amount of regenerated resin is replenished continuously or in batches at the top; the saturated part The resin is taken out, and then desorbed and regenerated in a small ion exchange column. 3. The treatment method of high alkali concentration sodium tungstate solution according to claim 1, characterized in that: decomposing scheelite concentrate WO ₃ grade is 64.5%, the amount of NaOH is 2.5 times of the theoretical amount, the decomposition temperature is 160°C, and the heat preservation The time is 4.5 hours, the decomposition rate is 97.45%, and the resulting liquid contains NaOH 51.3g/l, WO ₃ 97.8g/l; two Φ200×1400mm exchange columns are used for series adsorption operation, and the adsorption is carried out from top to bottom. After the column leaks through, it is connected to the second column, and after the second column is leaked, it is connected to the third column. After the third column is leaked, the first column is desorbed separately, and the working capacity of the first column is analyzed It is 125mgWO ₃ /ml wet resin, and the post-transaction liquid contains NaOH 47.7g/l and NaCl 24.0g/l. Evaporate the post-transition liquid to a NaOH concentration of 250g/l, and then add solid NaOH until the concentration is above 500g/l. Cool to about 30°C and let stand for 4 hours; after the NaCl is completely crystallized from the solution, centrifuge to obtain a concentrated NaOH solution containing less than 45g/l NaCl; the recovered NaOH is returned to the tungsten ore leaching operation, and the scheelite concentrate is decomposed under the same conditions. The decomposition rate is 97.17%. 4. The processing method of high alkali concentration sodium tungstate solution according to claim 1, characterized in that: the decomposition of high calcium wolframite contains 12.8% tungsten, the grade of WO ₃ is 43.4%, and the amount of NaOH is 3.5 times of the theoretical amount , the decomposition temperature is 160°C, the holding time is 40 hours, the decomposition rate is 98.45%, and the resulting liquid contains 49.2% NaOH, WO ₃ 58.1% g/l; two Φ200×1400mm exchange columns are used for series adsorption operation, countercurrent from bottom to top Adsorption, connect to the second column after the first column leaks through; the analysis shows that the working capacity is 117mgWO ₃ /ml wet resin; evaporate the post-transition liquid to a NaOH concentration of 1000g/l, cool and place it for 8 hours, and centrifuge The NaCl crystallizes; the resulting concentrated NaOH solution is returned to the leach batch. 5. The treatment method of high alkali concentration sodium tungstate solution according to claim 1, characterized in that: the feed liquid contains WO ₃ 25g/l, NaOH 20g/l, the exchange column is Φ16×36mm, and 4 columns are connected in series, Exchange in parallel; after the upstream column is saturated, desorb alone to obtain a working capacity of 128mg WO ₃ /ml wet resin. 6. the processing method of high alkali concentration sodium tungstate solution according to claim 2, is characterized in that: dense moving bed inner diameter 80mm, resin bed layer height 2000mm, containing NaOH 51.2g/l, WO ₃ 49.3g/l The feed liquid flows through the exchange column from bottom to top; check the effluent with cinchonine, and when tungsten leakage is found, take out the resin with a height of 300mm from the lower end of the column, and at the same time replenish the same amount of regenerated resin at the upper end, continue the exchange and adsorption, and take out the saturated The resin was loaded into a column with an inner diameter of 60 mm and desorbed with ammonia/ammonium chloride solution to obtain an exchange capacity of 122 mg WO ₃ /ml wet resin.