Method for preparing high-purity gamma-Fe2O3 iron oxide red pigment

Abstract

The invention relates to a method for preparing high-purity gamma-Fe2O3 iron oxide red pigment. The method includes the following steps: firstly, dissolving the ferrous sulfate solid in water, controlling the obtained solution to be at a certain temperature, adding a certain amount of a flocculating agent, and keeping at a certain temperature; after a certain time, filtering to obtain a refined ferrous sulfate solution; adding saturated ammonium bicarbonate solution into the refined ferrous sulfate solution for synthesizing iron carbonate and iron hydroxide precipitate with high magnetic properties under the conditions of a certain temperature and a pH value. According to the invention, the method is low in cost and simple and convenient to operate; the obtained product is high in stability and suitable for industrial production.

Description

technical field [0001] The invention relates to a high-purity gamma-Fe 2 o 3 The preparation method of iron oxide red pigment. Background technique [0002] In the early 1960s, ferrite was prepared by mixing analytically pure manganese, zinc, and iron sulfates as raw materials and calcining at 900°C. The ferrite produced by this method has high cost and serious environmental pollution. At the same time, the iron oxide factory developed a "high magnetic permeability iron oxide", which used oxalic acid as a precipitant, but was eliminated successively because of its high cost. [0003] In 1970 M.J.Ruther first published "Spray Burnt Iron Oxide for Ferrite". The characteristic of this method is that the pickling liquid during steel rolling is used as the raw material, and it is obtained by spraying and roasting at high temperature, and the product is cheap. It is characterized by product impurities such as SiO 2 High content, high requirements for equipment materials, and...

AI Technical Summary

Problems solved by technology

This method has the following problems in industrial production: 1. A large amount of titanium hydroxide precipitates are produced during the hydrolysis process, and the turbidity ratio of the sedimented material is about 2:1. It is easy to filter the clear night, but it is very difficult to filter the turbid liquid

If the turbid solution is discarded, the yield of ferrous sulfate is too low

2. During the hydrolysis process, the concentration decreases, the turbidity ratio increases, and the hydrolysis yield is high, but in the crystallization process, the higher the concentration, the lower the yield. The crystallization yield is 25%-30%, and the total yield is only 20% %about

The method used in the prior art is the neutralization oxidation method, and the synthesis method adopted in the Chinese patent CN1049142A uses ammonium bicarbonate to adjust the pH value, and oxidizes with air to generate Fe(OH) 3 Precipitation, high water content, this method has the following disadvantages: 1 The formed Fe(OH) 3 The precipitation has a large water content and is flocculent, which is difficult to filter and wash, and there is a lot of washing water, which makes industrial operation difficult

2. The magnesium impurity content in the product is easy to exceed the standard, 3. Fe(OH) 3 Precipitation takes a long time to dry, which takes 3-5 hours. After calcination, it becomes lumpy and needs to be crushed. There are many production procedures and high energy consumption.

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