CN1313360C

CN1313360C - Material charging method for preparing sodium hydrosulfite

Info

Publication number: CN1313360C
Application number: CNB2005100318354A
Authority: CN
Inventors: 叶永茂
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-07-08
Filing date: 2005-07-08
Publication date: 2007-05-02
Anticipated expiration: 2025-07-08
Also published as: CN1730384A

Abstract

The present invention relates to a method for preparing sodium dithionite, particularly to a material charging method for preparing sodium hydrosulfite. The present invention aims at providing a material charging method for preparing sodium hydrosulfite. The present invention is characterized by material mixing and compounding steps; in the material mixing steps, A and B suspension liquids are prepared, and the raw material of the A and the B suspension liquids and weight portions respectively conclude 3.5 to 4.5 weight portions of sodium formate, 13.5 to 15.5 weight portions of methanol, 3 to 4.2 weight portions of water, 19.5 to 20.5 weight portions of sodium formate, 11 to 12 weight portions of sodium carbonate, 64 to 67 weight portions of methanol, and 15 to 16 weight portions of water. In the compounding steps, the A suspension liquid is added into a compounding kettle first, SO2 is led into the compounding kettle under the condition that the temperature is from 75 DEG C to 80 DEG C and the pressure is from 0.1MPa to 0.18MPa, and the pH is regulated to from 4.3 to 4.5; when temperature rises to from 82 DEG C to 84DEG C and pressure rises to from 0.18MPa to 0.23MPa, the B suspension liquid and the SO2 are added then, the temperature is controlled from 82DEG C to 84 DEG C, the pressure is controlled to 0.18MPa to 0.23MPa, and the pH is controlled from 4.3 to 4.4; the SO2 is continuously added until the compounding reaction completely stops. The present invention is mainly used for the material charging procedures for preparing sodium hydrosulfite.

Description

Feeding method for preparing sodium hydrosulfite

Technical Field

The invention relates to a method for preparing sodium hydrosulfite, in particular to a feeding method for preparing sodium hydrosulfite.

Background

Existing preparation of sodium dithionite (Na)₂S₂O₄) The feeding method is that sodium formate, methanol and water are first compounded into suspension A, 15-20 wt% of the suspension is added into the synthesizing kettle, and the rest 80-85 wt% of the suspension A and suspension B compounded with sodium carbonate, methanol and sulfur dioxide are added into the synthesizing kettle simultaneously.

Disclosure of Invention

The invention aims to provide a feeding method for preparing sodium hydrosulfite, which overcomes the defects.

The technological scheme of the present invention is that sodium formate and sodium carbonate (or sodium pyrosulfite) are added into the synthesizing kettle simultaneously, and the sodium formate and sodium carbonate (or sodium pyrosulfite) are first compounded into suspension liquid B and then added into the synthesizing kettle and mixed with the suspension liquid A added into the synthesizing kettle for synthesis reaction.

The method comprises two steps of material preparation and synthesis, and is characterized in that: A. the preparation method comprises the following steps of preparing a suspension A and a suspension B, wherein the suspension A is prepared from the following raw materials in parts by weight: 3.5-4.5 parts of sodium formate, 13.5-15.5 parts of methanol and 3-4.2 parts of water, and then mixing the raw materials at normal temperature; the raw materials for preparing the suspension of the second kind by weight proportion are: 19.5-20.5 parts of sodium formate, 11-12 parts of sodium carbonate, 64-67 parts of methanol and 15-16 parts of water, and then mixing the raw materials at normal temperature and heating to 60-70 ℃ for later use;

B. the synthesis step is that the suspension A is added into a synthesis kettle, sulfur dioxide is introduced to adjust the pH value to 4.3-4.5 under the conditions that the temperature is 75-80 ℃ and the pressure is 0.1-0.18Mpa, when the temperature is increased to 82-84 ℃ and the pressure is increased to 0.18-0.23Mpa, the suspension B and the sulfur dioxide are added, the temperature is controlled to 82-84 ℃, the pressure is 0.18-0.23Mpa and the pH value is 4.3-4.4, the sulfur dioxide is continuously added after the suspension B is added until the reaction is completed, and the content of the sodium hydrosulfite in a sampling test is more than 87%.

The invention has the advantages that: the method changes the batching and feeding modes, thereby ensuring that the batching ratio of sodium formate to soda ash or sodium metabisulfite is equal to the instantaneous adding ratio of sodium formate to soda ash or sodium metabisulfite, and ensuring the completion of the synthetic reaction and the improvement of the yield of the final product (sodium hydrosulfite).

Drawings

The attached figure is a process flow diagram of the invention.

Detailed Description

The present invention and its embodiments are described in further detail below with reference to the accompanying drawings.

Example 1

Adding 14 parts of methanol, 4 parts of sodium formate and 4.2 parts of water into a 5M3 mixing pot with stirring, and stirring at normal temperature to prepare a suspension A; adding 66 parts of methanol, 20 parts of sodium formate, 11.5 parts of soda ash and 15.2 parts of water into a 13M3 mixing pot with stirring, stirring for 10 minutes to prepare a suspension B, and heating the suspension to 68 ℃ for later use; adding the suspension A into a synthesis kettle, introducing sulfur dioxide to adjust the pH value of the solution to 4.4 under the conditions of 76 ℃ and 0.15Mpa, adding the suspension B and the sulfur dioxide when the temperature is increased to 83 ℃ (caused by exothermic reaction) and the pressure is increased to 0.22Mpa, controlling the temperature to 83 ℃, the pressure to be 0.22Mpa and the pH value to be 4.4, continuously adding the sulfur dioxide after the suspension B is added until the synthesis reaction is complete, and sampling and testing the content of the sodium hydrosulfite to be 88.28%. The resultant is filtered and dried to obtain 46.30 portions of sodium hydrosulfite product with the purity of 90.20 percent.

The synthesis reaction is as follows:

example 2

Heating the suspension A to 69 deg.c, introducing sulfur dioxide at 78 deg.c into the reactor, adding the suspension B and introducing sulfur dioxide continuously until the synthesis reaction is completed, sampling to test the content of sodium dithionite to 87.54%, and drying to obtain 46.40 parts of solid sodium dithionite with purity of 89.34% as in example 1.

Example 3

Sodium metabisulfite (Na) was added to a 13M3 stirred batch kettle₂S₂O₅)20 parts of soda ash which replaces 11.5 parts of soda ash is used for preparing the suspension of the second kind, the sampling and testing are carried out after the synthetic reaction is finished, the content of the sodium hydrosulfite is 87.58 percent, the solid sodium hydrosulfite is obtained after drying, the purity is 90.64 percent, and the synthetic reaction is as follows:

the rest is the same as example 1.

Claims

1. A feeding method for preparing sodium hydrosulfite comprises two steps of material preparation and synthesis, and is characterized in that:

A. the preparation method comprises the following steps of preparing a suspension A and a suspension B, wherein the suspension A is prepared from the following raw materials in parts by weight: 3.5-4.5 parts of sodium formate, 13.5-15.5 parts of methanol and 3-4.2 parts of water, and then mixing the raw materials at normal temperature; the raw materials for preparing the suspension of the second kind by weight proportion are: 19.5-20.5 parts of sodium formate, 11-12 partsof sodium carbonate, 64-67 parts of methanol and 15-16 parts of water, and then mixing the raw materials at normal temperature and heating to 60-70 ℃ for later use;