Method for preparing sodium dichromate by sodium-based molten salt oxidation continuous carbonization

A sodium dichromate and molten salt oxidation technology, which is applied in the direction of chromate/dichromate, etc., can solve the problems of low resource utilization and low productivity, and achieve reduced infrastructure costs, low power consumption, and less heat dissipation Effect

Active Publication Date: 2015-01-14
HUBEI ZHENHUA CHEMICAL CO LTD
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

[0012] The purpose of the present invention is to overcome the problems of low productivity and low utilization rate of resources such as chromite and sodium which exist in the production process of sodium dichromate produced by chromite ore calcium-free roasting-sulfuric acid acidification method. , provides a method for producing sodium dichromate by oxidation and continuous carbonization of sodium-based molten salts, adopting the technical scheme of the present invention, greatly improves the productivity of the kiln, and also improves the resource utilization rate of chromium, sodium, etc. and dichromate The product quality of sodium dichromate has good economic benefits and development prospects. It is an optimized production process for making sodium dichromate from chromite ore or ferrochrome powder

Method used

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  • Method for preparing sodium dichromate by sodium-based molten salt oxidation continuous carbonization

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Effect test

Embodiment 1

[0046] to combine figure 1 , a kind of sodium-based molten salt oxidation continuous carbonization method of the present embodiment sodium dichromate method, its concrete steps are:

[0047] (A) Mixture:

[0048] will contain Cr 2 o 3 The mass percentage is 44.5%, and the particle size is 200 mesh. More than 90% of South African chromite powder and soda ash (sodium carbonate) are mixed uniformly as raw meal, and the mass ratio of South African chromite powder and soda ash (sodium carbonate) is 1:0.70 , the molar ratio of Cr in chromite powder to Na in soda ash (sodium carbonate) is 1.0:1.0, and the mass percentage of water in raw meal is 5%;

[0049] (B) Oxidation Roasting:

[0050]The raw meal in step (A) is gradually added into the rotary kiln to form a molten state for oxidation reaction, the burners at the feeding end and the discharging end are started to heat up, the raw meal is gradually melted in the rotary kiln (that is, the melting pool), and the reaction gener...

Embodiment 2

[0061] A kind of sodium-based molten salt oxidation continuous carbonization method of the present embodiment prepares the method for sodium dichromate, and its concrete steps are:

[0062] (A) Mixture:

[0063] will contain Cr 2 o 3 The mass percentage is 44.5%, and the particle size is 200 mesh. More than 90% of South African chromite powder and sodium bicarbonate are uniformly mixed as raw meal, wherein the mass ratio of South African chromite powder and sodium bicarbonate is 1:1.1, and the chromite ore The molar ratio of Cr in powder to Na in sodium bicarbonate is 1.0:1.0, and the mass percentage of water in raw meal is 7%;

[0064] (B) Oxidation Roasting:

[0065] The raw material in step (A) is added into the rotary kiln to form a molten state for oxidation reaction. The temperature in the rotary kiln is controlled at 1200~1250°C, the amount of molten salt is 80%, and the reaction time is 30 minutes. The molten salt in this example is from The siphon high-level outl...

Embodiment 3

[0076] A kind of sodium-based molten salt oxidation continuous carbonization method of the present embodiment prepares the method for sodium dichromate, and its concrete steps are:

[0077] (A) Mixture:

[0078] will contain Cr 2 o 3 The mass percentage is 44.5%, and the particle size is 200 mesh. More than 90% of South African chromite powder and solid sodium hydroxide are mixed uniformly as raw material, and the mass ratio of South African chromite powder and solid sodium hydroxide is 1:0.6, and the chromium The molar ratio of Cr in iron ore powder to Na in solid sodium hydroxide is 1.0:1.0, and the mass percentage of water in raw meal is 1%;

[0079] (B) Oxidation Roasting:

[0080] The raw material in step (A) is added to the rotary kiln to form a molten state for oxidation reaction. The temperature of the melt in the rotary kiln is controlled at 1200~1250°C, the residence time of the material is 30min, and the amount of molten salt is 55%. Molten salt flows out from ...

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Abstract

The invention discloses a method for preparing sodium dichromate by sodium-based molten salt oxidation continuous carbonization, belonging to the technical field of sodium dichromate. The method comprises the following steps of: (A) mixing materials: mixing chromite powder or ferrochromium powder, sodium-based alkali compound, sodium dichromate and reclaimed materials to form raw material; (B) oxidizing roasting: adding the raw material into a rotary kiln to form molten state and take oxidation reaction, wherein the draw ratio of the rotary kiln is 3-6; (C) leaching: conveying the molten salt into a granulator through a discharge chute to perform granulating and water quenching, and separating slurry to get the sodium chromate solution; (D) carbonization: neutralizing the sodium chromate solution and removing the aluminum from the sodium chromate solution to get the sodium chromate neutral solution; evaporating the sodium chromate neutral solution for concentration, dosing, and then, taking carbonization reaction in a continuous carbonization tower, treating the carbonized liquid with solid-liquid separation to get the carbonized clear liquid, and evaporating and crystallizing the carbonized clear liquid to get the sodium dichromate after separation. The method can effectively prevent accidents, such as accretion, improves the production rate of the kiln, improves the utilization rate of sodium resource by more than 50% and greatly improves the product quality of the sodium dichromate.

Description

technical field [0001] The invention belongs to the technical field of preparing sodium dichromate, more specifically, relates to a method for preparing sodium dichromate by oxidation continuous carbonization of sodium-based molten salt. Background technique [0002] Sodium dichromate is the most important product in the chromium salt industry. As a basic chemical raw material, it is widely used in chemical industry, light industry, printing and dyeing, medicine and other industries. It can be further processed into chromium salt series such as chromic anhydride, chromium hydroxide, basic chromium sulfate, etc. Products, used in metallurgy, machinery, building materials, petroleum, leather, electroplating, pigments, daily hardware and other industries, occupy an important position in the national economy. The basic production process of sodium dichromate is chromite oxidation roasting-sulfuric acid acidification method . [0003] The traditional production process of sodium...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01G37/14
Inventor 石大学
Owner HUBEI ZHENHUA CHEMICAL CO LTD
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