CN1054107C - Steppecd crystallization process purifying sodium thiocyanate solution - Google Patents
Steppecd crystallization process purifying sodium thiocyanate solution Download PDFInfo
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- CN1054107C CN1054107C CN95112111A CN95112111A CN1054107C CN 1054107 C CN1054107 C CN 1054107C CN 95112111 A CN95112111 A CN 95112111A CN 95112111 A CN95112111 A CN 95112111A CN 1054107 C CN1054107 C CN 1054107C
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- sodium thiocyanate
- nascn
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- thiocyanate solution
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Abstract
The present invention relates to a method for purifying a sodium thiocyanate solution with fractional crystallization, which comprises the steps as follows: the solution to be treated is heat, evaporated, concentrated and crystallized time and again at 25 to 100 DEG C; the mother liquid is separated to prepare reusable NaSCN crystal. The purified NaSCN solution with any concentration against 50%(+/-) of NaSCN can reduce the impurity content from at most 15% to at most 3%. The present invention has the advantages of simple technology, little investment, high efficiency, low cost and no need of additional acid and alkali or other solvents, and thus, the present invention is suitable for orlon preparation factory with wet spinning adopting NaSCN as a solvent and other occasions in which NaSCN is used and prepared.
Description
The present invention relates to the purifying method of sodium thiocyanate water solution, particularly in producing for the solvent wet spinning acrylic fibers with the Sodium Thiocyanate 99, a kind of method of Steppecd crystallization purification of sodium thiocyanate solution via.
At acrylic fibers is in the existing wet-spinning production technique of polyacrylonitrile fibre (PolyaryloniTrilefibres), is mostly to adopt Sodium Thiocyanate 99 (SodiumThiocyanate) solution as solvent.After the experience production process, built up impurity such as oligoacrylonitrile, sodium formiate, inorganic salt and colloid in this solvent, when recycled when foreign matter content is increased to certain limit, need take control techniques to remove impurity, otherwise will influence quality product.
At present, because of no economical rationality purifying method, or the sodium thiocyanate solution that foreign matter content is high undersells as waste product, or makes the sewage discharge contaminate environment.
Purifying method in the prior art mainly contains extraction process, active carbon adsorption, retardance resin method and resin anion(R.A) method, as CN86100573, ZN87107823, CN93108670, CN93118047, CN93118070, CN94101544 etc.
The all methods of prior art all have deficiency, for example:
1, the extraction genealogy of law becomes thiocyanic acid with the acidifying of Sodium Thiocyanate 99 elder generation, returns Sodium Thiocyanate 99 through isopropyl ether extraction, alkali neutralization.Isopropyl ether is inflammable easily fried, poisonous and high price, processing step complexity, and the facility investment height, difficult operation consumes a large amount of soda acids, the production cost height.
2, active carbon adsorption is to be applicable to when foreign matter content is very low in the sodium thiocyanate solution, and activated carbon adsorptive capacity is low, very easily loses efficacy, and regeneration step is loaded down with trivial details, and efficient is low.
3, the retardance resin, unavoidably also adsorbs other ionogen impurity in the absorption Sodium Thiocyanate 99 simultaneously because of being that two kinds of ion functions of absorption negative and positive are arranged, and can not remove a large amount of inorganic impurities, and NaSCN content causes secondary pollution still up to 5% in the liquid effluent.
4, resin anion(R.A) system becomes SO with sulfuric acid with resin earlier
4 --Type feeds Sodium Thiocyanate 99 again and makes resin become SCN
-Type, the sodium sulfate of impurity and generation discards, and take off with alkali cleaning and reclaim NaSCN, and resin becomes OH
-Type becomes SO with sulfuric acid with resin again
4 --Type carries out next circulation.This method flow process complexity, investment is high, difficult operation, being only applicable to the Sodium Thiocyanate 99 content range is 3～14% dilute solutions, the cost height, efficient is low.
5, all the other electroosmose processs, membrane separation process etc. still do not have industrial value.
Purpose of the present invention overcomes all drawbacks of above-mentioned prior art exactly, and for the acrylic fiber production process technology of wet-spinning solves this difficult problem, it is simple to develop a kind of technology, less investment, and the purification efficiency height, cost is low, reduce the improvement technology of polluting.
The objective of the invention is to realize by following measure:
Utilize Sodium Thiocyanate 99 and contained other impurity difference of solubleness under the differing temps in water, visualize a kind of evaporation concentration that comprises, cooling, crystallization, the method of the Steppecd crystallization purification of sodium thiocyanate solution via of processing steps such as separation, be about to pending solution be heated to 130～160 ℃ ± through evaporation concentration after crystallizer spray and descend, freezing air is sailed against the current the spray liquid cooling by the crystallizer bottom, and carries the moisture content that is evaporated and escape through condenser row; In the time of at the bottom of spray liquid drops down onto jar, temperature is reduced to 25～100 ℃, and the Sodium Thiocyanate 99 crystal is separated out, and gets rid of except that mother liquor through the discharge port whizzer, obtains the Sodium Thiocyanate 99 crystal; Mother liquor heats once more and repeats above-mentioned technical process 2～3 times, and repeatedly crystallization under differing temps can continue to obtain the Sodium Thiocyanate 99 crystal.
The same current technology of detection method, that is:
Total amount-NaSCN content (AgNO
3Method is measured)-moisture content=impurity content
This law is 50% ± time with respect to NaSCN content in being applicable to that existing acrylic fibre wet spinning is produced, and the sodium thiocyanate solution of any concentration of foreign matter content≤15% repeatedly after the crystallization, obtains the Sodium Thiocyanate 99 crystal.With respect to NaSCN content is 50% o'clock, foreign matter content reduces to≤and 3%, the Sodium Thiocyanate 99 rate of recovery is more than 70%, and recovery article is reusable in acrylic fiber production process.
Foreign matter content in waste liquor 〉=25%, can for other not high factory of purity requirement is used or be aided with other method again row reclaim.
Technology of the present invention is easy, efficient, less investment, cost are low, need not to add soda acid or other solvent, is a kind of method of purification of sodium thiocyanate solution via of suitable national conditions, is specially adapted to use NaSCN to do the acrylic fiber production process factory of solvent and other produces the occasion of NaSCN.
The present invention is further elaborated below in conjunction with drawings and Examples:
Fig. 1 is a Steppecd crystallization purification of sodium thiocyanate solution via process flow diagram.
Among the figure: steaming device in 1 mother liquor tank, 2 transferpumps, 3 well heaters, 4 crystallizers, 5 whizzers, 6 fans, 7 condensers, 8.
Embodiment 1: with 1015g concentration 48.1%, contain assorted 8.4% sodium thiocyanate solution and be heated to 130 ℃ of boilings, continue evaporation concentration to volume 553ml, after rising to 155 ℃, temperature is cooled to 25 ℃, then mass crystallization appears in solution, and dehydration separates, and mother liquor is handled once more as stated above, 45 ℃ of Crystallization Separation, collect crystal 3 80g altogether twice, it is 90.4% that silver nitrate method is surveyed Sodium Thiocyanate 99 content, the rate of recovery 70.30%, foreign matter content 3.6% is made into 50% solution and surveys that to contain assorted be 2.0%.
Embodiment 2: with 1203g concentration 24.1%, contain assorted 4.1% sodium thiocyanate solution and be heated to 115 ℃ of boilings, continue evaporation concentration to volume 415ml, be cooled to 30 ℃, Crystallization Separation remains mother liquor 280ml, continues to be concentrated into 227ml, be cooled to 49.5 ℃, crystallization separates, and collects crystal 2 34.51g altogether twice, survey contains assorted 5.05%, Sodium Thiocyanate 99 content 90.14%, the rate of recovery 72.91% is made into 50.11% solution and surveys that to contain assorted be 2.84%.
Embodiment 3: with 5017g concentration 52%, contain assorted 8.7% sodium thiocyanate solution and be heated to 138 ℃ of boilings, continue to be evaporated to volume 294.5ml, the thermometric degree is 157.5 ℃, is cooled to 42.5 ℃ of Crystallization Separation, and mother liquor is 1971ml, with mother liquid evaporation to 1589ml, be cooled to 100 ℃, Crystallization Separation, twice altogether crystal 2 145g.Survey Sodium Thiocyanate 99 content 90.51%.The rate of recovery 74.42%, containing assorted is 4.59%, is mixed with 50.16% solution and surveys that to contain assorted be 2.55%.
Embodiment 4: with concentration is 54.5%, contains assorted 13.03% sodium thiocyanate solution 5503g and is heated to 140 ℃, and boiling continues to be concentrated into 3015ml, be cooled to 34 ℃, Crystallization Separation is collected crystal 1501g, surveying purity is 92.1%, contains to mix 3.51%, surplus mother liquor 2904ml.
Mother liquid evaporation to 1501ml, is cooled to 51 ℃, and crystallization separates, and crystal 804.1g surveys purity 90.9% again, contains and mixes 4.1%, merges crystal twice, the rate of recovery 70.46%.
Twice crystalline content is made into 50% solution to be surveyed and contains assorted 1.89%.
Embodiment 5: with concentration is 15.1%, contains assorted 2.57% sodium thiocyanate solution 4011g and is heated to 112 ℃ of boilings, and continuing to be concentrated into volume is 6820ml, is cooled to 49 ℃ of crystallizations, separate mother liquor 456ml.Reheat is concentrated into 369ml, is cooled to 75.5 ℃ of Crystallization Separation, secondary altogether crystal 4 82g, surveying Sodium Thiocyanate 99 content is 91.2%, the rate of recovery 72.58% contains assortedly 4.02%, is made into 50.8% solution and surveys that to contain assorted be 2.25%.
Claims (1)
1. the method for a Steppecd crystallization purification of sodium thiocyanate solution via, it is characterized in that: after the pending sodium thiocyanate solution evaporation concentration, repeatedly crystallization between 25～100 ℃ separates the Sodium Thiocyanate 99 crystal that obtains behind the mother liquor, and is reusable in the acrylic fibre wet spinning is produced.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN95112111A CN1054107C (en) | 1995-08-24 | 1995-08-24 | Steppecd crystallization process purifying sodium thiocyanate solution |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN95112111A CN1054107C (en) | 1995-08-24 | 1995-08-24 | Steppecd crystallization process purifying sodium thiocyanate solution |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1174170A CN1174170A (en) | 1998-02-25 |
| CN1054107C true CN1054107C (en) | 2000-07-05 |
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ID=5079328
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN95112111A Expired - Fee Related CN1054107C (en) | 1995-08-24 | 1995-08-24 | Steppecd crystallization process purifying sodium thiocyanate solution |
Country Status (1)
| Country | Link |
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| CN (1) | CN1054107C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103723745A (en) * | 2013-01-22 | 2014-04-16 | 北京艾思合众环保科技有限公司 | Purification method for sodium thiocyanate |
| CN105819468A (en) * | 2016-03-09 | 2016-08-03 | 北京富海天环保科技有限公司 | Sodium sulfocyanate caking prevention apparatus and method thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2977188A (en) * | 1958-04-23 | 1961-03-28 | American Cyanamid Co | Method of purifying thiocyanate solutions |
| US2977187A (en) * | 1957-10-14 | 1961-03-28 | American Cyanamid Co | Purification of thiocyanate solutions |
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1995
- 1995-08-24 CN CN95112111A patent/CN1054107C/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2977187A (en) * | 1957-10-14 | 1961-03-28 | American Cyanamid Co | Purification of thiocyanate solutions |
| US2977188A (en) * | 1958-04-23 | 1961-03-28 | American Cyanamid Co | Method of purifying thiocyanate solutions |
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| Publication number | Publication date |
|---|---|
| CN1174170A (en) | 1998-02-25 |
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