CN109455762B

CN109455762B - Method for preparing calcium tungstate by utilizing chloropyridine tar

Info

Publication number: CN109455762B
Application number: CN201811475009.2A
Authority: CN
Inventors: 柯有胜; 张孝朋
Original assignee: Inner Mongolia Jiaruimi Fine Chemical Co ltd
Current assignee: Inner Mongolia Jiaruimi Fine Chemical Co ltd
Priority date: 2018-12-04
Filing date: 2018-12-04
Publication date: 2020-11-13
Anticipated expiration: 2038-12-04
Also published as: CN109455762A

Abstract

The invention discloses a method for preparing calcium tungstate by utilizing chloropyridine still residue tar, belonging to the field of organic still residue regeneration and recovery in fine chemical engineering. In the process of preparing pyridine chloride, the kettle residue obtained by post-treatment comprises deactivated tungsten hexachloride, overchlorinated pyridine, pyridine oxide, coke, pyridine polymer and the like, and high-purity calcium tungstate is obtained through neutralization reaction, decoloration and calcium tungstate precipitation. The process is simple and easy to operate, realizes the recycling of tungsten resources, avoids the waste of the tungsten resources and the pollution to the environment, has the tungsten recovery rate of over 95 percent, and has great economic benefit and social benefit.

Description

Method for preparing calcium tungstate by utilizing chloropyridine tar

Technical Field

The invention relates to a process method for preparing calcium tungstate by using tungsten hexachloride as a catalyst to produce chloropyridine and tar containing tungsten hexachloride generated in the production process.

Background

At present, in the production process of domestic chloropyridine (short for 2-chloro-5-trichloromethylpyridine), 3-methylpyridine is taken as a raw material, chlorine is introduced into the raw material, and the chloropyridine is obtained through two-stage chlorination reaction. The chloropyridine can be sold as a product and is also a raw material of fluoropyridine (which is short for 2-fluoro-5-trifluoromethylpyridine).

In the preparation process of chloropyridine, tungsten hexachloride is mostly adopted as a nucleophilic substitution reaction catalyst in the secondary chlorination reaction, a mixture after the reaction is cooled and settled, the upper layer of liquid is a chloropyridine product, the lower layer of the chloropyridine product is an inactivated catalyst and kettle residual tar, and the chloropyridine product and the kettle residual tar are mixed together and are not easy to separate.

Most manufacturers treat tungsten hexachloride and tar together as hazardous waste, or mix tungsten hexachloride into waste water, so that water pollution is caused. Some manufacturers burn the tar mixture containing tungsten hexachloride to extract tungsten, but the treatment process is complex, and the burning generates a large amount of harmful substance dioxin, so the burning treatment process is not economical. Therefore, the waste of tungsten resources is caused, and the purpose of resource recycling is not achieved.

Disclosure of Invention

In order to overcome the defects, the process method for preparing the calcium tungstate by the tar containing the tungsten hexachloride is simple in process and high in recovery rate. And (3) performing neutralization reaction, decoloration reaction and precipitation reaction on residual tar in the chloropyridine kettle in sequence to prepare the calcium tungstate.

The technical scheme of the invention is as follows: a process for preparing calcium tungstate from the tar oil of tungsten hexachloride includes such steps as neutralizing the residual tar oil containing tungsten hexachloride, separating tar oil from tungsten hexachloride, laying aside for layering to obtain sodium tungstate solution, reducing for decolouring, dripping aqueous solution of calcium chloride, preparing calcium tungstate, filtering and baking.

A method for preparing calcium tungstate by using chloropyridine still residual tar is characterized by comprising the following steps: and (3) performing neutralization reaction, decoloration reaction and precipitation reaction on residual tar in the chloropyridine kettle in sequence to prepare the calcium tungstate.

Further, in the above technical scheme, the neutralization reaction is: and (3) dropwise adding an aqueous alkali solution into the tar mixture containing the tungsten hexachloride, adjusting the pH value of the water phase to 7-8, standing for layering, and filtering to obtain a red brown sodium tungstate aqueous solution.

Further, in the above technical scheme, the aqueous alkali solution is selected from sodium hydroxide or potassium hydroxide aqueous solution, and the mass fraction is 20-50%.

Further, in the above technical scheme, the decoloring reaction is: adding a decolorizing agent into the red brown sodium tungstate aqueous solution, stirring and heating to 50-60 ℃, continuously stirring and reacting, and filtering while hot to obtain colorless transparent liquid.

Further, in the technical scheme, the decolorizing agents are activated carbon, silica gel and ferrous salt, and the adding amount is 1-3% of the mass ratio of the sodium tungstate aqueous solution.

In the process of recycling the residual tar in the kettle, the decoloring is key, firstly a decoloring agent is added for heating and decoloring, then the filtering is carried out, and then the pH is adjusted by adding alkali, so that the effect is not ideal, and the black brown solution is obtained. When neutralization is carried out firstly and then decolorization is carried out, the key point is that a small amount of ferrous salt and silica gel are added for combination, and meanwhile, a light yellow solution can be converted into a nearly colorless transparent solution in the presence of activated carbon. A clear yellow solution still exists after pure activated carbon decolorization.

Further, in the above technical solution, the ferrous salt is selected from ferrous chloride or ferrous sulfate; the mass ratio of the active carbon to the silica gel to the ferrous salt is 70-80: 15-20: 3-5.

Further, in the above technical scheme, the precipitation reaction is: and (3) dropwise adding a calcium chloride aqueous solution into the sodium tungstate aqueous solution, wherein the reaction temperature is 60-80 ℃, the pH value at the end point of the reaction is 6-7, so as to obtain calcium tungstate precipitate, and filtering and drying to obtain a calcium tungstate finished product.

Further, in the above technical scheme, the chloropyridine still residual tar comprises deactivated tungsten hexachloride, a pyridine perchloride, a pyridine oxide, coke and a pyridine polymer.

Preferably, in the above technical solution, the specific operations are as follows:

1. and (3) neutralization reaction: and (3) dropwise adding a sodium hydroxide aqueous solution with the mass fraction of 30% into the tar mixture containing the tungsten hexachloride, stirring, adjusting the pH value of the aqueous phase to 7, standing for layering, and filtering to obtain a reddish brown sodium tungstate aqueous solution.

2. And (3) decoloring reaction: adding a decolorizing agent which is composed of activated carbon, ferrous sulfate and silica gel (the mass ratio of the activated carbon, the ferrous sulfate and the silica gel is 80:3:17) in a mass ratio of 2% into the sodium tungstate aqueous solution, heating to 50-60 ℃ under stirring, continuously stirring for 1-5h, and filtering while the solution is hot to obtain a colorless transparent sodium tungstate aqueous solution.

3. Precipitation reaction: and (3) dropwise adding a calcium chloride aqueous solution into the colorless transparent sodium tungstate aqueous solution, wherein the reaction temperature is 60-80 ℃, and the pH value at the end point of the reaction is 6-7 to obtain calcium tungstate precipitate, filtering, and drying to obtain a calcium tungstate finished product.

The invention has the beneficial effects that:

the invention takes the residual tar of the kettle containing the components of tungsten hexachloride and the like as the raw material, and the finished product of calcium tungstate is obtained through neutralization reaction, decoloration and precipitation. The tar source is the residue in the process of preparing pyridine chloride, and the residue comprises deactivated tungsten hexachloride, over-chlorinated pyridine, pyridine oxide coke, pyridine polymer and the like. The process is simple and easy to operate, realizes the recycling of tungsten resources, avoids the waste of the tungsten resources and the pollution to the environment, and accords with the current circular economic policy and the industrial policy of tungsten nonferrous metals. The recovery rate of the tungsten in the process is up to more than 95%, and great economic and social benefits are brought to enterprises.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

Example 1

The method comprises the steps of carrying out high-temperature two-stage chlorination on 3-methylpyridine and chlorine in the presence of a catalytic amount of tungsten hexachloride, after the reaction is finished, cooling a chlorination reactor to 8-10 ℃ to enable the inactivated catalyst to be completely settled, wherein the upper layer is dark red transparent liquid, and the lower layer is a brownish black kettle residual coke object. The brown black kettle residue coke contains deactivated tungsten hexachloride, pyridine polychloride, pyridine oxide coke, pyridine polymer and the like, wherein the weight content of the tungsten hexachloride is about 51.5-54.5%.

Sucking out the upper layer of transparent liquid, taking 1kg of lower layer coke in a 2L three-neck round-bottom flask, starting mechanical stirring, dropwise adding a 30% sodium hydroxide aqueous solution into the tar mixture, adjusting the pH value of the aqueous phase to 7, standing for layering, and filtering to obtain 1.65kg of a reddish brown sodium tungstate aqueous solution.

Putting the sodium tungstate aqueous solution into a 2L three-neck round-bottom flask, adding a decolorizing agent which is composed of activated carbon, ferrous sulfate and silica gel (the mass ratio of the activated carbon, the ferrous sulfate and the silica gel is 80:3:17), starting stirring, heating in a water bath to 55 ℃, keeping the temperature, stirring for 1 hour, and filtering while hot to obtain 1.32kg of colorless transparent sodium tungstate aqueous solution.

And (3) putting the sodium tungstate aqueous solution into a 5L beaker, dropwise adding a calcium chloride aqueous solution with the mass fraction of 40%, heating in a water bath to 60 ℃, and obtaining calcium tungstate precipitate with the pH value of 6-7 at the end of the reaction, filtering and drying to obtain 376g of finished calcium tungstate with the W content of 62.5%.

Example 2

1kg of the tar residue obtained in example 1 was placed in a 2L three-neck round-bottom flask, mechanical stirring was started, a 40% aqueous solution of potassium hydroxide was added dropwise to the tar mixture, the pH of the aqueous phase was adjusted to 7, and the mixture was allowed to stand for delamination and filtration to obtain 1.84kg of a reddish brown aqueous solution of potassium tungstate.

Putting the aqueous solution of potassium tungstate into a 2L three-neck round-bottom flask, adding a decolorizing agent which is composed of activated carbon, ferrous sulfate and silica gel (the mass ratio of the activated carbon, the ferrous sulfate and the silica gel is 80:3:17), starting stirring, heating in a water bath to 55 ℃, keeping the temperature, stirring for 1 hour, and filtering while hot to obtain 1.57kg of colorless transparent aqueous solution of sodium tungstate.

Putting the potassium tungstate aqueous solution into a 5L beaker, dropwise adding a calcium chloride aqueous solution with the mass fraction of 40%, heating in a water bath to 60 ℃, wherein the pH value at the end point of the reaction is 6-7, obtaining calcium tungstate precipitate, filtering, and drying to obtain 369g calcium tungstate finished products with the W content of 62.8%.

Example 3

1kg of the still residue tar obtained in example 1 was placed in a 2L three-neck round-bottom flask, mechanical stirring was started, a 30% aqueous solution of sodium hydroxide was added dropwise to the tar mixture, the pH of the aqueous phase was adjusted to 7, and the mixture was allowed to stand for delamination and filtration to obtain 1.60kg of a reddish brown aqueous solution of sodium tungstate.

Putting the sodium tungstate aqueous solution into a 2L three-neck round-bottom flask, adding a decolorizing agent which is composed of 32g of activated carbon, ferrous sulfate and silica gel (the mass ratio of the activated carbon, the ferrous sulfate and the silica gel is 75:5:20), starting stirring, heating in a water bath to 55 ℃, keeping the temperature, stirring for 1h, and filtering while hot to obtain 1.35kg of colorless transparent sodium tungstate aqueous solution.

Putting the potassium tungstate aqueous solution into a 5L beaker, dropwise adding a calcium chloride aqueous solution with the mass fraction of 40%, heating in a water bath to 60 ℃, wherein the pH value at the end of the reaction is 6-7, obtaining a calcium tungstate precipitate, filtering, and drying to obtain 353g of a finished calcium tungstate product with the W content of 61.6%.

Example 4

And (3) putting 100kg of the residual tar in the kettle in the example 1 into a 250L reaction kettle, starting mechanical stirring, dropwise adding a sodium hydroxide aqueous solution with the mass fraction of 30% into the tar mixture, adjusting the pH value of the water phase to 7, standing for layering, and performing suction filtration in a filter tank to obtain 172kg of a reddish brown sodium tungstate aqueous solution.

And transferring the sodium tungstate aqueous solution to another 250L reaction kettle, adding a decolorizing agent which is composed of activated carbon, ferrous sulfate and silica gel (the mass ratio of the activated carbon, the ferrous sulfate and the silica gel is 80:3:17) in a mass ratio of 3.5Kg, starting stirring, heating in a water bath to 60 ℃, keeping the temperature and stirring for 3 hours, keeping the temperature and then carrying out hot filtration to obtain 138Kg of colorless transparent sodium tungstate aqueous solution.

And transferring the potassium tungstate aqueous solution into a 500L reaction kettle, starting stirring, dropwise adding a calcium chloride aqueous solution with the mass fraction of 40%, heating in a water bath to 80 ℃, wherein the pH value at the end point of the reaction is 7 to obtain a calcium tungstate precipitate, and filtering and drying to obtain 33.6Kg of finished calcium tungstate with the W content of 63.1%.

The foregoing embodiments have described the general principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are merely illustrative of the principles of the present invention, and that various changes and modifications may be made without departing from the scope of the principles of the present invention, and the invention is intended to be covered by the appended claims.

Claims

1. A method for preparing calcium tungstate by using chloropyridine still residual tar is characterized by comprising the following steps: performing neutralization reaction, decolorization reaction and precipitation reaction on residual tar in a chloropyridine kettle in sequence to prepare calcium tungstate; the chloropyridine still residual tar comprises deactivated tungsten hexachloride, over-chlorinated pyridine, pyridine oxide, coke and pyridine polymer; the neutralization reaction is that alkaline water solution is dripped into the tar mixture containing the tungsten hexachloride, the pH value of the water phase is adjusted to 7-8, the mixture is kept stand for layering, and the red brown sodium tungstate water solution is obtained by filtration; the decoloring reaction is that a decoloring agent is added into a red brown sodium tungstate aqueous solution, the temperature is raised to 50-60 ℃, the stirring reaction is continued, and the colorless transparent liquid is obtained by filtering while the solution is hot; the decolorizing agent is active carbon, silica gel and ferrous salt, and the adding amount is 1-3% of the mass ratio of the sodium tungstate aqueous solution.

2. The method of preparing calcium tungstate according to claim 1, wherein: the alkaline water solution is selected from sodium hydroxide or potassium hydroxide water solution, and the mass fraction is 20-50%.

3. The method of preparing calcium tungstate according to claim 1, wherein: the ferrous salt is selected from ferrous chloride or ferrous sulfate; the mass ratio of the active carbon to the silica gel to the ferrous salt is 70-80: 15-20: 3-5.

4. The method of preparing calcium tungstate according to claim 1, wherein: and the precipitation reaction is to drop a calcium chloride aqueous solution into a sodium tungstate aqueous solution, the reaction temperature is 60-80 ℃, the pH value at the end point of the reaction is 6-7, so as to obtain calcium tungstate precipitate, and the calcium tungstate precipitate is filtered and dried, so as to obtain a calcium tungstate finished product.