Method for preparing sodium chromate by adopting sulfate byproduct iron cake as calcium-free roasting filler

A technology of calcium-free roasting and sodium chromate, applied in the direction of chromate/dichromate, can solve the problems of ring formation and low oxidation efficiency, and achieve the advantages of improving reaction efficiency, high oxidation efficiency and solving environmental pollution problems. Effect

Active Publication Date: 2014-10-15
SICHUAN YINHE CHEM
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Problems solved by technology

[0009] In view of the above problems to be solved, the present invention provides a method for preparing sodium chromate by using sulfuric acid by-product iron slag as calcium-free roasting filler, using sulfuric acid by-product iron slag as filler, which solves the problem of traditional calcium-free roasting ring formation, oxidation Low efficiency and other issues, the chromium slag produced in the production, its main component is Fe 2 o 3 , Fe 2 o 3 It is enriched in the slag, with a content of 50% to 70%, Cr 6+ Less than 5mg / kg (as Na 2 CrO 4 count), can be directly used in the production of stainless steel

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] A. Ingredients: Dry the sulfuric acid by-product iron slag, grind and sieve until the moisture content is 0.1%, the fineness is 120 mesh, and Fe is removed by magnetic separation 3 o 4 , according to the mass ratio of chromite (48% by mass percentage in terms of chromium trioxide), soda ash (98% by mass percentage containing sodium carbonate), and 70% by-product iron slag by sulfuric acid The mixture is 1:0.9:0.3 and shaped by a ball forming machine.

[0038] B. Preheating and solidification: Preheat and solidify the molding material in a rotary kiln at a temperature of 600°C and a preheating time of 30 minutes.

[0039] C. Oxidation calcination: calcinate the preheated molding material in a rotary kiln, and feed pure oxygen, the calcination temperature is 1100°C, and the time is 60min.

[0040] D. Wet milling and filtration: After cooling the calcined clinker, add water to the ball mill for wet milling, and then vertical plate and frame filter to obtain sodium chroma...

Embodiment 2

[0043] A. Ingredients: Dry the sulfuric acid by-product iron slag, grind and sieve until the moisture content is 0.1%, the fineness is 160 mesh, and Fe is removed by magnetic separation 3 o 4 , according to the mass ratio of chromite (48% by mass percentage in terms of chromium trioxide), soda ash (98% by mass percentage containing sodium carbonate), and 70% by-product iron slag by sulfuric acid The mixture is 1:0.9:0.6 and shaped by a ball forming machine.

[0044] B. Preheating and solidification: Preheat and solidify the molding material in a rotary kiln at a temperature of 700°C and a preheating time of 30 minutes.

[0045] C. Oxidation calcination: calcinate the preheated molding material in a rotary kiln, and feed pure oxygen, the calcination temperature is 1200°C, and the time is 90min.

[0046] D. Wet milling and filtration: The calcined clinker is wet milled and subjected to vertical plate and frame pressure filtration to obtain sodium chromate solution and iron-ric...

Embodiment 3

[0049] A. Ingredients: Dry the sulfuric acid by-product iron slag, grind and sieve until the moisture content is 0.1%, the fineness is 200 mesh, and Fe is removed by magnetic separation 3 o 4 , according to the mass ratio of chromite (48% by mass percentage in terms of chromium trioxide), soda ash (98% by mass percentage containing sodium carbonate), and 70% by-product iron slag by sulfuric acid The mixture is 1:0.9:0.6 and shaped by a ball forming machine.

[0050] B. Preheating and solidification: Preheat and solidify the molding material in a rotary kiln at a temperature of 700°C and a preheating time of 60 minutes.

[0051] C. Oxidation calcination: calcinate the preheated molding material in a rotary kiln, and feed pure oxygen, the calcination temperature is 1300°C, and the time is 120min.

[0052] D. Wet milling and filtration: The calcined clinker is wet milled and subjected to vertical plate and frame pressure filtration to obtain sodium chromate solution and iron-ri...

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Abstract

The invention discloses a method for preparing sodium chromate by adopting sulfate byproduct iron cake as a calcium-free roasting filler. The method mainly comprises the following steps: batching of sulfate byproduct iron cake, chromite and caustic soda, preheating of the ball material, high-temperature oxygen-enriched calcination, wet milling and pressure filtration. According to the invention, the sulfate byproduct iron cake is adopted as a filler, so that the gas contact property is good during roasting, meanwhile, a catalytic oxidation role is played and the sulfate byproduct iron cake is efficiently utilized. The chromium yield in the filtrate is relatively high and can be more than 90%; the filter residue contains more than 50% of Fe2O3 which can be all used for preparing stainless steel, so that the problem of underlying environmental pollution of Cr<6+> is solved from the pollution source.

Description

technical field [0001] The invention relates to the field of inorganic chromium salt production, in particular to a method for preparing sodium chromate by using sulfuric acid by-product iron slag as calcium-free roasting filler. Background technique [0002] At present, there are mainly two methods of chromium salt production: calcium roasting and calcium-free roasting. Calcium roasting belongs to the national elimination process, and the biggest disadvantages of the existing calcium-free roasting process compared with calcium roasting process are: 1. The conversion rate of chromium is low. 2. The roasting temperature should not be too high, and it can be increased when the temperature is high The conversion rate of chromium is low, but the liquid phase composition in the kiln increases correspondingly, which is easy to form rings in the kiln and affects production. [0003] The main principle of the calcium roasting process is to use calcium-containing compounds such as d...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G37/14
Inventor 李先荣陈宁董明甫谢友才黄玉西
Owner SICHUAN YINHE CHEM
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