CN110759838B - Treatment method of thiourea feed liquid - Google Patents
Treatment method of thiourea feed liquid Download PDFInfo
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- CN110759838B CN110759838B CN201911098819.5A CN201911098819A CN110759838B CN 110759838 B CN110759838 B CN 110759838B CN 201911098819 A CN201911098819 A CN 201911098819A CN 110759838 B CN110759838 B CN 110759838B
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- thiourea
- feed liquid
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- thiocyanate
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C335/00—Thioureas, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups
- C07C335/02—Thiourea
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
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Abstract
The invention provides a method for treating thiourea feed liquid, which comprises the following steps: filling SH-root type anion resin in the resin column, and performing ion exchange with thiourea feed liquid by using the resin to obtain the treated thiourea feed liquid. Compared with the prior art, the treatment method provided by the invention selects the specific ion exchange resin to carry out ion exchange on the thiourea feed liquid, so that thiocyanate ions enter the resin and HS are replaced at the same time‑Ionic, and thiourea production process HS‑Participate in the reaction, thereby effectively removing thiocyanate ions in the thiourea feed liquid without damaging the thiourea feed liquid and influencing the cyclic use of the thiourea feed liquid, further obviously reducing the content of the thiocyanate ions in thiourea products and improving the product quality. Experimental results show that the content of thiocyanate in the treated thiourea feed liquid obtained by the treatment method provided by the invention is not more than 1.33%, and further the content of thiocyanate in the obtained thiourea product is not more than 0.013%, so that the quality standard requirement of the product is met.
Description
Technical Field
The invention relates to the technical field of chemical production, in particular to a method for treating thiourea feed liquid.
Background
Thiourea, molecular formula (NH2)2CS, relative molecular mass 76.12, white rhombic or acicular bright crystals; combustible, the melting point is 170 ℃ to 180 ℃, and high-temperature decomposition is carried out; it is soluble in cold water and ethanol, and almost insoluble in diethyl ether. At present, water, lime nitrogen (calcium cyanamide) and hydrogen sulfide gas are industrially used as raw materials, absorption synthesis reaction is carried out in a synthesis kettle to prepare a solution containing thiourea, the solution is filtered and purified for many times, cooled and crystallized, crystals are centrifugally dried after solid-liquid separation, a finished product is prepared after drying, and mother liquor obtained by centrifugal separation is returned to a system for recycling.
Ammonium thiocyanate and thiourea are isomers, and thiourea is converted into ammonium thiocyanate under the high-temperature condition. In the thiourea synthesis reaction, the reaction temperature is 85 ℃, a large amount of thiourea is converted into ammonium thiocyanate at the moment, the ammonium thiocyanate is easy to dissolve in water, along with the cyclic utilization of thiourea feed liquid, the content of thiocyanate in the feed liquid is gradually accumulated, and finally, the content of thiocyanate in a thiourea product exceeds an index requirement (the index requirement is that the content of thiocyanate is less than or equal to 0.02 percent), the thiourea feed liquid contains more than 12 percent of thiourea, if the feed liquid cannot be recycled, not only is economic loss caused, but also environmental pollution is caused, and therefore, a method for removing thiocyanate in the thiourea feed liquid needs to be found.
At present, because a thiourea feed liquid system is complex and has sulfate radicals, thiosulfate radicals and sulfhydryl ions, a proper thiourea feed liquid treatment method does not exist in the prior art, namely, the treatment is not carried out; when the thiocyanate radical reaches a certain amount, the system is concentrated and crystallized to obtain partial thiourea product (the thiourea recovery rate is about 60%), and the rest feed liquid is used as waste water for treatment.
Disclosure of Invention
In view of the above, the present invention aims to provide a treatment method for thiourea feed liquid, which can effectively remove thiocyanate ions in thiourea feed liquid, thereby significantly reducing thiocyanate ion content in thiourea products and improving product quality.
The invention provides a method for treating thiourea feed liquid, which comprises the following steps:
filling SH-root type anion resin in the resin column, and performing ion exchange with thiourea feed liquid by using the resin to obtain the treated thiourea feed liquid.
Preferably, the volume of the resin column is 1.5m3～2.5m3。
Preferably, the filling rate of the SH group-type anionic resin is 85% to 95%.
Preferably, the thiourea feed liquid contains 12-30 wt% of thiourea, 1-5 wt% of thiocyanate, 5-35 g/L of calcium hydrosulfide, 0.1-1.5 wt% of sulfate radical and 0.5-5 wt% of ammonium radical ions.
Preferably, the flow rate of the thiourea feed liquid for ion exchange is 4m3/h～20m3/h。
Preferably, the temperature for ion exchange of the thiourea feed liquid is 20-45 ℃.
Preferably, the time for ion exchange of the thiourea feed liquid is 1-60 min.
Preferably, before the resin is used for ion exchange with thiourea feed liquid, the method further comprises:
and (3) washing the SH radical type anion resin with water.
The invention provides a method for treating thiourea feed liquid, which comprises the following steps: filling SH-root type anion resin in the resin column, and performing ion exchange with thiourea feed liquid by using the resin to obtain the treated thiourea feed liquid. Compared with the prior art, the treatment method provided by the invention selects the specific ion exchange resin to carry out ion exchange on the thiourea feed liquid, so that thiocyanate ions enter the resin and HS-ions are replaced at the same time, and HS is used in the thiourea production process-Participate in the reaction, consequently can not introduce new impurity ion and influence the product quality, get rid of the thiocyanate ion in the thiourea feed liquid simultaneously to can effectively get rid of the thiocyanate ion in the thiourea feed liquid under the prerequisite that does not produce destruction, influence thiourea feed liquid recycling to thiourea feed liquid, further obviously reduce the thiocyanate ion content in the thiourea product, promote the product quality. Experimental results show that the content of thiocyanate in the treated thiourea feed liquid obtained by the treatment method provided by the invention is not more than 1.33%, and further the content of thiocyanate in the obtained thiourea product is not more than 0.013%, so that the quality standard requirement of the product is met.
In addition, the treatment method provided by the invention is simple to operate and easy to control, is suitable for industrial production, and has a wide application prospect.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a method for treating thiourea feed liquid, which comprises the following steps:
filling SH-root type anion resin in the resin column, and performing ion exchange with thiourea feed liquid by using the resin to obtain the treated thiourea feed liquid.
In the invention, the resin column is an ion exchange column, and the columnar pressure vessel for carrying out the ion exchange reaction is the exchange equipment for the ion exchange by the column method. In the present invention, the volume of the resin column is preferably 1.5m3～2.5m3More preferably 2m3. The source of the resin column is not particularly limited in the present invention, and commercially available products known to those skilled in the art may be used.
In the invention, the SH-radical anion resin is strong-base SH-radical resin, the resin is used for carrying out ion exchange with thiourea feed liquid, thiocyanate ions enter the resin, and HS is replaced at the same time-HS in process of producing ion and thiourea-The SH radical type anion resin is selected to participate in the reaction, so that new impurity ions are not introduced to influence the quality of the product.
The filling method is not particularly limited, and the technical scheme of uniform filling known to those skilled in the art can be adopted. In the present invention, the filling ratio of the SH group-type anionic resin is preferably 85% to 95%, and more preferably 90%.
In the present invention, before the resin is used for ion exchange with thiourea solution, it preferably further comprises:
and (3) washing the SH radical type anion resin with water.
In the present invention, the thiourea feed liquid is a thiourea feed liquid generated in the industrial thiourea production process well known to those skilled in the art. In the invention, the content of thiourea in the thiourea solution is preferably 12 wt% to 30 wt%, and more preferably 20 wt% to 24 wt%; the content of thiocyanate radicals in the thiourea solution is preferably 1 to 5 wt%, and more preferably 2 to 2.5 wt%; the content of the calcium hydrosulfide in the thiourea feed liquid is preferably 5-35 g/L, more preferably 15-28 g/L; the content of sulfate radical in the thiourea solution is preferably 0.1-1.5 wt%, and more preferably 0.4-0.75 wt%; the content of ammonium ions in the thiourea solution is preferably 0.5 wt% to 5 wt%, and more preferably 1 wt% to 2.7 wt%. Therefore, the treatment method provided by the invention seems to be simple, but the method is not simple in practical application, and the selection of the resin and the treatment parameters influence the treatment effect due to the complex thiourea feed liquid system.
The invention has no special limitation on the way of ion exchange between the thiourea feed liquid and the resin, and adopts the technical scheme that the feed liquid pump pumps the feed liquid into the resin column, which is well known to the technical personnel in the field. And adjusting the flow of the feed liquid pump to control the flow of the feed liquid for ion exchange, thereby controlling the time for the feed liquid and the resin to carry out ion exchange. In the invention, the flow rate of the thiourea feed liquid for ion exchange is preferably 4m3/h～20m3H, more preferably 8m3/h。
In the present invention, the temperature at which the thiourea solution is ion-exchanged is preferably 20 to 45 ℃, and more preferably 25 ℃. In the invention, the resin is crushed due to over-high temperature, and the treatment effect of the resin is damaged; if the temperature is too low, thiourea in the feed liquid can be separated out on the surface of the resin, and cannot be fully contacted with the feed liquid, so that the aim of removing thiocyanate radicals cannot be fulfilled.
In the present invention, the time for the thiourea solution to perform ion exchange (i.e., the adsorption exchange time) is preferably 1min to 60min, and more preferably 5min to 30 min. In the invention, the short adsorption and exchange time can affect the treatment effect of the feed liquid, thiocyanate radicals in the feed liquid can not be effectively removed, and the treatment efficiency can be reduced due to the long time.
The treatment method provided by the invention uses ion exchange resin to remove thiocyanate ions in thiourea feed liquid, and controls parameters such as resin type, adsorption time, treatment temperature and the like.
The invention provides a method for treating thiourea feed liquid, which comprises the following steps: filling SH-root type anion resin in the resin column, and performing ion exchange with thiourea feed liquid by using the resin to obtain the treated thiourea feed liquid. Compared with the prior art, the treatment method provided by the invention selects the specific ion exchange resin to carry out ion exchange on the thiourea feed liquid, so that thiocyanate ions enter the resin and HS are replaced at the same time-Ionic, and thiourea production process HS-Participate in the reaction, consequently can not introduce new impurity ion and influence the product quality, get rid of the thiocyanate ion in the thiourea feed liquid simultaneously to can effectively get rid of the thiocyanate ion in the thiourea feed liquid under the prerequisite that does not produce destruction, influence thiourea feed liquid recycling to thiourea feed liquid, further obviously reduce the thiocyanate ion content in the thiourea product, promote the product quality. Experimental results show that the content of thiocyanate in the treated thiourea feed liquid obtained by the treatment method provided by the invention is not more than 1.33%, and further the content of thiocyanate in the obtained thiourea product is not more than 0.013%, so that the quality standard requirement of the product is met.
In addition, the treatment method provided by the invention is simple to operate and easy to control, is suitable for industrial production, solves the problem of enrichment of thiocyanate by cyclic utilization of thiourea feed liquid, and has great application significance in the field of industrial production of thiourea.
To further illustrate the present invention, the following examples are provided for illustration. The main components and contents of thiourea feed solutions used in the following examples of the present invention are shown in table 1.
TABLE 1 data on the main components and contents of the thiourea feed liquids used in the examples of the present invention
| Thiourea content | Thiocyanate content | Calcium hydrogen sulfide content | Sulfate radical content | Ammonium ion content |
| 20％～24％ | 2％～2.5％ | 15g/L～28g/L | 0.4％～0.75％ | 1％～2.7％ |
Example 1
At 2m3The resin column is uniformly filled with the treated SH radical type anion resin 1.8m3The resin is used for carrying out ion exchange with thiourea feed liquid, and the flow of the thiourea feed liquid is controlled to be 8m3And h, ion exchange time of the thiourea feed liquid and the resin is 5min, and the temperature of the thiourea feed liquid is 25 ℃, so that the treated thiourea feed liquid is obtained.
Sampling and detecting the content of thiocyanate in the thiourea feed liquid, crystallizing the obtained treated thiourea feed liquid, and detecting the content of thiocyanate in the thiourea product, wherein the detection results are shown in table 2.
Example 2
At 2m3The resin column is uniformly filled with the treated SH radical type anion resin 1.8m3The resin is used for carrying out ion exchange with thiourea feed liquid, and the flow of the thiourea feed liquid is controlled to be 16m3And h, performing ion exchange on the thiourea solution and the resin for 2.4min, wherein the temperature of the thiourea solution is 25 ℃, and thus obtaining the treated thiourea solution.
Sampling and detecting the content of thiocyanate in the thiourea feed liquid, crystallizing the obtained treated thiourea feed liquid, and detecting the content of thiocyanate in the thiourea product, wherein the detection results are shown in table 2.
Example 3
At 2m3The resin column is uniformly filled with the treated SH radical type anion resin 1.8m3The resin is used for carrying out ion exchange with thiourea feed liquid, and the flow of the thiourea feed liquid is controlled to be 4m3And h, carrying out ion exchange on the thiourea solution and the resin for 30min, wherein the temperature of the thiourea solution is 25 ℃, and thus obtaining the treated thiourea solution.
Sampling and detecting the content of thiocyanate in the thiourea feed liquid, crystallizing the obtained treated thiourea feed liquid, and detecting the content of thiocyanate in the thiourea product, wherein the detection results are shown in table 2.
Comparative example 1
At 2m3The resin column is uniformly filled with the treated SH radical type anion resin 1.8m3The resin is used for carrying out ion exchange with thiourea feed liquid, and the flow of the thiourea feed liquid is controlled to be 8m3And h, ion exchange time of the thiourea feed liquid and the resin is 5min, and the temperature of the thiourea feed liquid is 50 ℃, so that the treated thiourea feed liquid is obtained.
Sampling and detecting the content of thiocyanate in the thiourea feed liquid, crystallizing the obtained treated thiourea feed liquid, and detecting the content of thiocyanate in the thiourea product, wherein the detection results are shown in table 2.
Comparative example 2
At 2m3The resin column is uniformly filled with the treated SH radical type anion resin 1.8m3The resin is used for carrying out ion exchange with thiourea feed liquid, and the flow of the thiourea feed liquid is controlled to be 8m3And h, ion exchange time of the thiourea feed liquid and the resin is 5min, and the temperature of the thiourea feed liquid is 14 ℃, so that the treated thiourea feed liquid is obtained.
Sampling and detecting the content of thiocyanate in the thiourea feed liquid, crystallizing the obtained treated thiourea feed liquid, and detecting the content of thiocyanate in the thiourea product, wherein the detection results are shown in table 2.
TABLE 2 data of the test results of examples 1 to 3 and comparative examples 1 to 2
| Content of thiocyanate in feed liquid/%) | Content of thiocyanate in thiourea products% | |
| Untreated feed liquid | 2.31 | 0.035 |
| Example 1 | 0.52 | 0.007 |
| Example 2 | 1.33 | 0.013 |
| Example 3 | 0.47 | 0.005 |
| Comparative example 1 | 2.06 | 0.033 |
| Comparative example 2 | 2.11 | 0.035 |
As can be seen from Table 2, the content of thiocyanate in the thiourea product obtained by the method for treating the thiourea feed liquid provided by the invention is low, and the product quality standard requirement is met, while the content of thiocyanate in the thiourea product obtained by the untreated thiourea feed liquid exceeds the product quality standard requirement, and the product belongs to an unqualified product.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (6)
1. A method for treating thiourea feed liquid comprises the following steps:
filling SH-root type anion resin in the resin column, and performing ion exchange on the resin and thiourea feed liquid to obtain treated thiourea feed liquid;
the thiourea feed liquid contains 12-30 wt% of thiourea, 1-5 wt% of thiocyanate radical, 5-35 g/L of calcium hydrosulfide, 0.1-1.5 wt% of sulfate radical and 0.5-5 wt% of ammonium radical ion;
the temperature of the thiourea feed liquid for ion exchange is 20-45 ℃.
2. The process according to claim 1, wherein the volume of the resin column is 1.5m3～2.5m3。
3. The treatment method according to claim 1, wherein the filling rate of the SH group-type anionic resin is 85 to 95%.
4. The process of claim 1, wherein the thiourea feed solution is ion exchanged at a flow rate of 4m3/h～20m3/h。
5. The treatment method according to claim 1, wherein the time for ion exchange of the thiourea feed solution is 1 to 60 min.
6. The treatment method according to any one of claims 1 to 5, further comprising, before using the resin for ion exchange with the thiourea feed solution:
and (3) washing the SH radical type anion resin with water.
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| CN112876393A (en) * | 2021-01-19 | 2021-06-01 | 浙江工业大学 | Method for continuously synthesizing and purifying thiourea by using ammonium thiocyanate |
| CN114307359B (en) * | 2021-11-12 | 2023-05-12 | 格林智慧环保科技(山西)有限公司 | Thiourea and calcium thiocyanate membrane separation method |
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