CN101186315A

CN101186315A - Method for producing (standard) sodium pyrosulfite from sodium sulfite

Info

Publication number: CN101186315A
Application number: CNA200610149110XA
Authority: CN
Inventors: 黄中杰
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-11-17
Filing date: 2006-11-17
Publication date: 2008-05-28

Abstract

The invention relates to a method for producing standard sodium pyrosulfite by using sodium sulfite, the principle the method is the same as making sodium pyrosulfite by using traditional soda or caustic soda. The control method is different and the same intermediate material is formed and then transformed into odium pyrosulfite. 1. The standard sodium pyrosulfite preparation method by using soda (or the caustic): 2Na2SO3+4SO2+2H2O - 4NaHSO3+2CO2 4NaHSO3 - 2Na2S2O5 (sodium pyrosulfite) +2H2O; 2. the standard sodium pyrosulfite preparation method by using sodium sulfite: Na2SO3+SO2+H2O - 2NaHSO3 2NaHSO3 - 2Na2S2O5 (sodium pyrosulfite) +H2O, the required content of the sodium sulfite material ranges from 45 percent to 96 percent (the standard), in the methods, the dry methods thereof are divided into all-dry method and semi-dry method according to the purity of sodium sulfite content. The wet method is more convenient than the traditional method and the process is shortened, but standard soda or caustic soda are needed to be added according to the increasing content of sodium sulfite to adjust the process. Mother liquor application needs to be controlled and confirmed, such as sodium sulfite of sodium hydrosulfite (sodium formate method) can be recycled twice or three times, tested and then transformed to generate sodium thiosulfate additionally. The sodium pyrosulfite is produced according to the standard of crude sodium sulfite formed by indigoid mixed alkali, standard soda or caustic soda needs to be added for adjusting, the mother liquor produces the potassium salts additionally.

Description

S-WAT is produced (standard) Sodium Pyrosulfite method

It is main or with sodium hydroxide and SO that national standard Sodium Pyrosulfite product, tradition adopt yellow soda ash ₂Effect is produced, and adopts S-WAT (the crude product S-WAT that comprises certain content) beyond example still.

Because S-WAT (the thick Asia that comprises certain content) is similar with Sodium Pyrosulfite, then enormous amount if adopt new method, can form very big benefit surely.

In China's vat powder (sodium formate method) is produced, the a large amount of S-WATs of byproduct, and self in a large number Sodium Pyrosulfite make raw material, if can adopt S-WAT to produce Sodium Pyrosulfite (standard substance), just can form the production of recycle, produce suitable benefit.

In addition, in indigo dye is produced,,, can fundamentally solve the approach that mixes the alkali regeneration equally, form suitable benefit if form (standard) Sodium Pyrosulfite again by producing S-WAT because rich producing mixed alkali in a large number.

S-WAT (the thick Asia that comprises certain content), produce qualified or the standard Sodium Pyrosulfite consistent with soda ash or production of caustic soda principle, but process is different with working method, promptly all passes through SO ₂Forming sodium bisulfite is transformed again.

Process is respectively:

Soda ash or caustic soda method: 2Na ₂CO ₃+ 4SO ₂+ 2H ₂O → 4NaHSO ₃+ 2CO ₂

4NaHSO ₃→2Na ₂S ₂O ₅+2H ₂O

S-WAT method: Na ₂SO ₃+ SO ₂+ H ₂O → 2NaHSO ₃

2NaHSO ₃→2Na ₂S ₂O ₅+H ₂O

Because S-WAT comprises the thick Asia of certain content, the more traditional soda ash of its method (or caustic soda) method has quite different, and its method still can be divided into dry method and wet method two classes.

Dry method, procedure is:

(1) with the dry product of qualified S-WAT, under agitation slowly adds liquid SO ₂(salable product), pH value are dry about 4-4.6, and its product is qualified Sodium Pyrosulfite.

(2) with the thick Asia of certain content, under stirring action, slowly add SO ₂Or logical SO ₂Gas, pH value are about 4-4.6, wash, dewater, are dried to standard substance, mother liquid recycle with a certain amount of normal water (tap water or nature, qualified reuse water).

Here the thick S-WAT of certain content is that S-WAT content 45% is with nonstandard grade.

Wet method, procedure is:

(1) qualified S-WAT is dissolved in normal water (tap water, qualified natural water or handle qualified reuse water) and forms saturated solution.

(2) feed SO ₂Gas or liquid pH value are about 4-4.6, form the sodium bisulfite crystallization.

(3) dewater, be dried to qualified Sodium Pyrosulfite

The S-WAT of purity not enough (defective) must replenish soda ash or caustic soda according to content, forms the inferior crystallization of qualified Jiao.Though its mother liquor water and survey, with its foreign matter content decision whether can be again with or produce other kind separately.

Example 1: 500kg under agitation slowly adds liquid SO with vat powder (sodium formate method) byproduct S-WAT (content 90%) ₂, pH value is about 4-4.6, replenishes tap water 500kg dissolving, washing 2 hours, dewaters, is dried to the standard Sodium Pyrosulfite under the normal temperature, and mother liquor water can be applied mechanically secondary to three, and row is produced Sulfothiorine again, can accomplish zero release.

Example 2: 500kg under agitation slowly adds SO with criterion of acceptability sodium sulphite (content 96%) ₂PH value is about 4-4.6, and drying is the standard Sodium Pyrosulfite.

Example 3: mix alkali with indigo and produce the crude product 500kg of S-WAT content more than 50%, add water 1000kg, add standard soda ash 100kg again, logical SO ₂Gas or SO ₂Liquid, pH value are about 4-4.6, form burnt inferior crystallization, dewater, are dried to qualified Sodium Pyrosulfite, the mother liquor detection, and other material such as potassium content height can be produced products such as vitriolate of tartar.

Claims

1. S-WAT production standard Sodium Pyrosulfite method, its claim context has following several aspect:

(1) S-WAT content is in 45% to 96% (standard substance) scope.

(2) used SO ₂Raw material is liquid SO ₂Or gas SO ₂, purity does not have particular requirement.

2. the dry method of present method is had any different by S-WAT purity difference, is two kinds of absolutely dry method and semidryings, and its difference needs remove impure other material with the normal water washing in semidrying.

The wet method principle is identical with traditional method production Sodium Pyrosulfite, need interpolation standard soda ash or caustic soda because of content is different, but technology shortens.

3. no matter vat powder (sodium formate method) byproduct S-WAT is crude product or product up to standard, all in present method scope.

4. indigo mixes the S-WAT of alkali production also within present method scope.