Method for preparing anhydrous sodium chromate

An anhydrous sodium chromate and sodium chromate technology, which is applied in the production of chromate/dichromate and bulk chemicals, can solve the problems of waste of resources and high production costs, improve manpower and solve the problem of easy moisture absorption , the effect of good fluidity

Active Publication Date: 2017-11-14
SICHUAN YINHE CHEM
View PDF8 Cites 0 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This production process not only prepares sodium chromate containing tetrahydrate, but also goes back to the way of the process, resulting in waste of resources and high production costs

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Method for preparing anhydrous sodium chromate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] A method for preparing anhydrous sodium chromate, comprising the following steps:

[0027] Step 1, the sodium chromate alkaline solution 8m 3 Carbonation solution 1m prepared by carbonization method 3 Add it into the pretreatment storage tank, take a sample and analyze the pH to be 8.2, and retest the pH to be 8.3 after stirring at room temperature for 15 minutes to obtain the sodium chromate pretreatment solution; the concentration of the carbonized solution is 925g L -1 (in Na 2 Cr 2 o 7 2H 2 O meter), pH is 5.8;

[0028]Step 2. Pump the sodium chromate pretreatment solution to the continuous evaporation crystallizer, use steam as the heat source, raise the temperature to 81°C, start the vacuum pump, and control the internal pressure of the evaporator at -0.09MPa; Feed rate of sodium chromate pretreatment liquid, observe the precipitation of sodium chromate crystals, when the solid-liquid ratio is 50%, discharge to the concentrated liquid storage tank;

[0029]...

Embodiment 2

[0031] A method for preparing anhydrous sodium chromate, comprising the following steps:

[0032] Step 1, the sodium chromate alkaline solution 7m 3 Carbonation solution 2m prepared by carbonization method 3 Add it into the pretreatment storage tank, sample and analyze the pH to be 7.6, retest the pH to be 7.6 after stirring at room temperature for 15 minutes, and obtain the sodium chromate pretreatment solution; the concentration of the carbonized solution is 925g L -1 (in Na 2 Cr 2 o 7 2H 2 O meter), pH is 5.8;

[0033] Step 2: Pump the sodium chromate pretreatment solution to the evaporation crystallizer, use steam as the heat source, raise the temperature to 90°C, start the vacuum pump, and control the internal pressure of the evaporator at -0.07MPa. During the evaporation process, the feeding rate of the sodium chromate pretreatment liquid is well controlled, and the precipitation of sodium chromate crystals is observed. When the solid-liquid ratio is 42%, the mater...

Embodiment 3

[0036] A method for preparing anhydrous sodium chromate, comprising the following steps:

[0037] Step 1, the sodium chromate alkaline solution 6m 3 Carbonation solution 3m prepared by carbonization method 3 Add in the pretreatment storage tank, take a sample and analyze the pH7.1, retest the pH7.15 after stirring at room temperature for 15 minutes, and obtain the sodium chromate pretreatment solution; the concentration of the carbonized solution is 925g L -1 (in Na 2 Cr 2 o 7 2H 2 O meter), pH is 5.8;

[0038] Step 2: Pump the sodium chromate pretreatment solution to the evaporation crystallizer, use steam as the heat source, raise the temperature to 102°C, start the vacuum pump, and control the pressure inside the evaporator at -0.04MPa. During the evaporation process, the feeding rate of the sodium chromate pretreatment liquid is well controlled, and the precipitation of sodium chromate crystals is observed. When the solid-liquid ratio is 36%, the material is discharg...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

PUM

No PUM Login to view more

Abstract

The present invention discloses a method for preparing anhydrous sodium chromate. The method comprises the steps of mixing a sodium chromate alkali solution with a carbonating solution in proportion of (1:1) to (8:1), and then, adjusting the pH to 6.5-8.5 to obtain a pretreatment solution of sodium chromate; placing the pretreatment solution of sodium chromate in an evaporation crystallizer for vacuum evaporation at the temperature of 80 DEG C to 120 DEG C under the pressure of 0.01 MPa to 0.09 MPa; and when the solid-to-liquid ratio reaches 10%-50% through vacuum evaporation, performing solid-liquid separation at the temperature of 70 DEG C or above to obtain anhydrous sodium chromate and a filtrate. Based on the technology characteristics of sodium dichromate preparation by a carbonation method, high-quality anhydrous sodium chromate is successfully prepared by the method disclosed by the invention, with the main content being equal to or greater than 99.5% and the content of all impurities such as sulfate being less than 0.001%; moreover, the product does not absorb moisture or cake even if stored for a long term, and has good fluidity. The problems of sodium chromate tetrahydrate on easy moisture absorption, caking and poor fluidity are successfully solved. The method also brings into play the superiority of a production process of preparing sodium dichromate from a chromium salt by the carbonation method, so that two high-quality chemical products can be produced on one production line.

Description

technical field [0001] The invention relates to the field of chemical raw material preparation, in particular to a method for preparing anhydrous sodium chromate. Background technique [0002] Sodium chromate is the basic raw material of the chromium salt industry, and is widely used in many important economic fields, such as ink, paint, pigment, metal corrosion inhibitor, organic synthetic oxidant, and various fields such as tanning and printing and dyeing. At present, the market demand of pigments and other industries is more than 20,000 tons. However, these industries do not directly use sodium chromate as raw material. Instead, they all use sodium red alum as raw material, and use NaOH to return to sodium chromate, and then carry out downstream product production and application. Sodium chromate is prepared through four processes of sulfuric acid acidification (or carbonization, electrolysis), evaporation, crystallization, and centrifugation to obtain sodium chromate. I...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

Application Information

Patent Timeline
no application Login to view more
Patent Type & Authority Patents(China)
IPC IPC(8): C01G37/14
CPCC01G37/14C01P2006/80C01P2006/82Y02P20/54
Inventor 周中田陈宁董明甫王方兵谢友才黄先东张良魏俊刘玉洪
Owner SICHUAN YINHE CHEM
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Try Eureka
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap