CN1055064C

CN1055064C - Purifying technology for sodium thiocyanate

Info

Publication number: CN1055064C
Application number: CN97105655A
Authority: CN
Inventors: 杨彦功
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-01-21
Filing date: 1997-01-21
Publication date: 2000-08-02
Anticipated expiration: 2017-01-21
Also published as: CN1188742A

Abstract

The present invention relates to a technology for purifying sodium thiocyanate, which has the main technical characteristics that NaSCN solution, or NaSCN crystals and NaSCN solids are heated at high temperature; then residual impurities are separated; at high temperature, organic impurities in the NaSCN are treated with evaporation, sublimation, decomposition and carbonization. Thereby, the organic impurities are thoroughly separated from the NaSCN. The present invention has the advantages of simple technology, low cost and high efficiency of removing impurities, and the content of the impurities in the NaSCN reaches less than 1%.

Description

The purification process of Sodium Thiocyanate 99

The invention belongs to the purification of industrial chemicals, particularly a kind of purification process of Sodium Thiocyanate 99.

NaSCN is a kind of important chemical material, and mainly as the raw material of the solvent of acrylic fiber production process and dyestuff, pesticide industry, these purity of using NaSCN all have strict service requirements for it.For example, DYE PRODUCTION requires that foreign matter content must be controlled at below the 3-5% among the NaSCN: acrylic fiber production process then will be looked for novelty to contain to mix with NaSCN solution and must be lower than 1%.But in the acrylic fiber production process process, the NaSCN solvent that recycles, its foreign matter content still can constantly accumulate and be increased to more than 8～10%, make acrylic fibers can't keep ordinary production.In order to reduce the influence of foreign matter content among the NaSCN, people explore and have taked multiple reduction and purify the measure of foreign matter content among the NaSCN.The isopropyl ether extraction process is typically arranged, and ion exchange method postpones resin method, electroosmose process.Also have gac, silica gel soil, molecular sieve adsorption removal of impurities in addition, recrystallization separates auxiliary impurity-removing methods such as removal of impurities.These methods have impurity-eliminating effect in various degree, but or because cost height or because efficient is low, or because seriously polluted etc., all make industrial application be subjected to certain limitation.For example, the extraction process dust removal rate is very high, but one ton of NaSCN of every processing, cost reaches four or five thousand yuan; And for example method such as charcoal absorption, recrystallization cost is lower, but impurity-eliminating effect is undesirable.

The purpose of this invention is to provide the impurity and purification technology of a kind of new NaSCN, cost is low, the dust removal rate height.

NaSCN purification process of the present invention, major technique characteristics are to add the alkali used as stabilizers in the thick NaSCN solution, to make the solution alkalize, evaporation is earlier solidified, and high-temperature heating treatment is carried out in 300～1000 ℃ again in 280～300 ℃ of following fusions in the back, be diluted to the aqueous solution then, filter, filtrate is handled.

Mix containing in the middle of the NaSCN almost all is organic low molecular and organic oligomer thing, these materials are under molten state, the part organic impurity can evaporate, distils, decompose, continue to heat up again (generally more than 300 ℃) the impurity carbonization is finished, in the time of 300～1000 ℃ organic impurity substantially carbonization finish.Under the high temperature impurity evaporate, distillation, decomposition and carbonization, thoroughly separate thereby be easy to NaSCN.Separate residual impurity then.The auxiliary process of separating residual impurity is: the NaSCN to pyroprocessing dissolves, filters, the solid particle polluter after the elimination charing.Filtrate can be by being adsorbed decolouring deironing etc., and impurity has been separated fully, and the back promptly obtains finished product by concentrated or crystallization.

This scheme is suitable for the removal of impurities of NaSCN crystal or pressed powder equally, directly 280～300 ℃ of following fusions, carries out high-temperature heating treatment in 300～1000 ℃ again.

For fear of NaSCN decomposition at high temperature, NaSCN adds the alkali used as stabilizers before heat treated.Alkaloids such as NaOH, Ca (OH) 2, Ba (OH) 2 etc., its add-on makes NaSCN solution or crystal, solid be alkalescence, preferably the pH value of NaSCN solution is 7-10, if NaSCN crystal or solid, the add-on of alkali is generally 0.01～1% of NaSCN amount.

Advantage of the present invention:

Technology is simple, and cost is low, non-environmental-pollution, and the dust removal rate height can make the foreign matter content among the NaSCN reach below 1%.

Embodiment one:

With used assorted 5～10% the NaSCN solution that contains of acrylic fiber production process, add NaOH solution, the PH that makes NaSCN solution is 8, subsequently this NaSCN solution is carried out evaporation concentration and become pressed powder, pressed powder is placed elevated temperature vessel to be warming up to 280～300 ℃ again, make the NaSCN fusion, the organic impurity evaporation distillation among the NaSCN is decomposed, continue to be warming up to 300～1000 ℃, making wherein, organic impurity decomposes carbonization.Put into dissolving tank after the cooling, be dissolved into 30～50% the NaSCN aqueous solution, filter then with de-salted water, the solid particle polluter after the elimination carbonization, filtrate is with the charcoal absorption deironing of decolouring, and till the solution clear, the solution reconcentration obtains finished product.

Embodiment two:

Commercially contain assorted to be 3～5% thick NaSCN crystal powder, to add 0.01～1% Ba (OH) 2 pulvis, mix thoroughly, powder is placed the elevated temperature vessel fusion that heats up, 300～1000 ℃ of following carbonizations, purification process is finished by the flow process of embodiment one in the back.

Claims

1, a kind of purification process of Sodium Thiocyanate 99 is characterized in that making the solution alkalize with adding the alkali used as stabilizers in the thick NaSCN solution, evaporation is earlier solidified, and high-temperature heating treatment is carried out in 300～1000 ℃ again in 280～300 ℃ of following fusions in the back, be diluted to the aqueous solution then, filter, filtrate is separated.

2, purification process according to claim 1 is characterized in that described filtrate carries out adsorption-edulcoration, at last through concentrating or crystallization.

3, purification process according to claim 2 is characterized in that filtrate uses charcoal absorption.

4, purification process according to claim 1, it is 7～10 that the add-on that it is characterized in that alkali makes the PH of NaSCN solution.

5,, it is characterized in that described alkali is NaOH, Ba (OH) according to claim 1,4 described purification process ₂