Iron oxide pigment is a very important inorganic color pigment with good pigment quality and wide application field.

The production methods of iron oxide red are divided into dry method and wet method, of which dry method mainly includes green alum (that is, ferrous sulfate heptahydrate) calcination method,

Iron yellow calcination method, iron black calcination method, in addition to hematite as raw materials of natural iron oxide mineral ultrafine crushing method.

The wet process mainly includes the sulfate (that is, ferrous sulfate or a solution containing ferrous sulfate) process and nitrate

(i.e. ferric nitrate, ferrous nitrate or solution containing ferric nitrate salt) method, mixed acid method; The wet process depends on the neutralizer used in the two-step oxidation process,

It can also be divided into iron sheet method and ammonia method.

1. About dry process:

Dry process is the traditional and original iron oxide red production process in China, which has the advantages of simple production process, short flow and relatively less equipment investment.

The disadvantage is that the product quality is slightly poor, and the calcination process has harmful gases, which has a significant impact on the environment. For example, in the calcination process, a large amount of sulfur-containing gas is produced.

In recent years, based on the comprehensive utilization of iron-containing waste, dry processes such as sulfuric acid slag process and iron ore powder acidizing roasting process have emerged in China.

Its advantage is that the process is simple, less investment, the disadvantage is that the quality of the product is low, can only be applied to the low-end field.

2, about the wet process:

The wet process uses ferrous sulfate or ferrous nitrate, ferric sulfate and ferric nitrate as raw materials, and adopts the production method of iron oxide red by first preparing crystal seeds and then oxidizing to produce iron red.

The raw material used can be either ferrous sulfate, ferrous nitrate solid raw material, or an aqueous solution containing ferrous sulfate, ferrous nitrate, ferrous sulfate, and ferrous nitrate. the

The neutralizer used can be either iron sheet, iron filings, or alkali or ammonia. In recent years, based on the comprehensive utilization of industrial waste, titanium dioxide has been produced as a by-product of ferrous sulfate or

Ferric sulfate solution and the method of preparing iron oxide red industrial pigment with waste acid or waste water of pickling steel plant as raw materials belong to the category of wet process.

The neutralizer used is still iron sheet, iron filings, alkali or ammonia. The advantage of the wet process is that the product quality is excellent, and different types of serialized iron oxide red products can be prepared.

The disadvantage is that the process is long, the production process has high energy consumption, a large number of acidic wastewater is generated, and there is a lack of effective comprehensive utilization of acidic wastewater.