Method for recovering iron from red mud

Abstract

The invention relates to a method for recovering iron from red mud. The method for recovering the iron from the red mud belongs to the technical field of mineral processing, and comprises the steps ofin a suspension roaster, pre-oxidizing a magnetic-separated red mud material in an air atmosphere, and completely transforming spathic iron and brown iron ore in the red mud material into hematite; utilizing self-stored heat of a material obtained through pre-oxidization treatment for reducing the material in a reducing gas atmosphere so as to completely reduce hematite in the material into Fe3O4; re-oxidizing the obtained material in an air atmosphere, and transforming at least part of Fe3O4 in the material into gamma-Fe2O3; and carrying out magnetic separation on the material obtained through the treatment in the steps. The method provided by the invention solves the problems of long calcination time, high temperature, higher reducing gas CO content, loss of valuable elements, high energy consumption and the like in an existing process method for treating the red mud so as to recover fine iron powder.

Description

technical field [0001] The invention relates to a method for recovering iron from red mud, belonging to the technical field of mineral processing. Background technique [0002] Red mud is the solid waste residue produced in the alumina production process. It is red because it contains a large amount of iron oxide, so it is called red mud. In my country, about 1.0-1.8 tons of red mud is discharged for every 1 ton of alumina produced. It is estimated that more than 70 million tons of red mud are discharged every year in the world, and the annual discharge of red mud by my country's aluminum industry is about 60 million tons. At present, a large amount of red mud is treated by open-air storage, and no effective treatment method has been formed. In addition, a large amount of valuable metals contained in red mud cannot be utilized, resulting in a waste of resources. With the increase of the cumulative stockpiles of red mud in our country, the comprehensive development and uti...

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Problems solved by technology

Chinese patent CN102626670A discloses a method for preparing iron concentrate powder by magnetizing and roasting red mud in a rotary kiln. The reaction time of this method is long (25-50min), and the content of CO in the reducing atmosphere required is relatively high (15%-25 %), high energy consumption; the red mud lumps entering the kiln are below 10mm, and the red mud itself is a fine powder with a particle size of less than 0.02mm accounting for more than 65%. During the operation of the rotary kiln, the red mud lumps are bound to collide and pulverize , forming rings and skins at high temperatures, deteriorating working conditions

Chinese invention patent CN102628907A discloses a method of circulating fluidized bed magnetization roasting treatment of red mud to prepare iron powder. The red mud is directly dried and then preheated and magnetized. This method does not deal with a large amount of alkali in the red mud, such as potassium and sodium. During the roasting process of metal ions, there is a problem of agglomeration and skinning after vaporization-condensation; and this method also has a long reaction time (25-50min), and the material needs to be roasted repeatedly in the circulating fluidized bed. The content of CO is relatively high (16% ~ 22%), the problem of energy consumption

In addition, the above two magnetization roasting treatments are Bayer high-iron red mud with an iron content of more than 30%. For red mud with a low iron content below 30%, direct reduction roasting with the above method will inevitably cause The energy consumption per unit of roasted mineral products is high, and the product recovery rate is low due to the entrainment effect of fine particles in the magnetic separation process after roasting

Chinese invention patent CN201510124963.7 discloses a method for preparing iron concentrate powder from red mud by flash magnetization roasting. Red mud is enriched, alkali removed, dried to powder, preheated and flash roasted, and iron concentrate is obtained by weak magnetic separation. ore, this method causes a large amount of valuable elements to be lost after alkali removal, and cannot achieve efficient recycling of minerals; and most of the iron in red mud exists in hematite or limonite, and this roasting method cannot guarantee iron The uniformity of mineral reduction also makes the application of this method have certain limitations

[0005] To sum up, in the existing process of processing red mud to recover iron concentrate, there are problems such as long roasting time, high temperature, high content of CO in reducing gas, loss of valuable elements and high energy consumption.

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