Process for producing sodium carbonate, aluminum oxide and blended cement from red mud

Abstract

The invention discloses a process for producing sodium carbonate, aluminum oxide and blended cement from red mud. The process comprises the following steps: diluting red mud to obtain diluted red mud,feeding the diluted red mud into an a-stage washing unit, feeding the diluted red mud into a carbonization unit A for reaction, feeding the reacted diluted red mud into a b-stage washing unit for washing, feeding the diluted red mud into a filtering unit, filtering to obtain low-sodium red mud, and mixing and grinding the low-sodium red mud and lime to obtain blended cement; in the process, collecting washing water that is used for washing red mud in the b-stage washing unit, feeding the washing water into the a-stage washing unit for a-stage washing; collecting the washing water that is usedfor washing the red mud in the a-stage washing unit; delivering one part of the washing water to an m-stage evaporation and concentration unit, then sending the washing water to a carbonization unitB, introducing the washing water to a filtering and washing unit, separating out aluminum hydroxide and liquid sodium carbonate in the filtering and washing unit, drying and burning aluminum hydroxideto obtain aluminum oxide, and making liquid sodium carbonate pass through n evaporation and concentration units and an evaporation and drying unit to obtain sodium carbonate.

Description

technical field [0001] The invention belongs to the technical field of red mud utilization, and in particular relates to a process for producing soda ash, alumina and blended cement by using red mud. Background technique [0002] Red mud is industrial solid waste discharged from the aluminum industry when extracting alumina. It is called red mud because it contains a large amount of iron oxide and its appearance is similar to red soil. Due to different ore grades, production methods and technical levels, about 1.0-1.8 tons of red mud will be discharged for every 1 ton of alumina produced. Red mud mainly contains iron, sodium, aluminum, calcium, silicon and other elements. Among them, sodium and aluminum elements mainly exist in the form of sodium aluminate, which can be written as NaAlO 2 or Na 2 O Al 2 o 3 . [0003] In the prior art, the red mud needs to be separated and washed, and finally discharged to the red mud storage yard. Existing red mud washing generally ad...

AI Technical Summary

Problems solved by technology

Since the existing technology cannot reduce the sodium content in the red mud to a lower level, and more sodium in the cement will cause great harm, the most typical is the alkali-aggregate reaction, the sodium-alkali in the cement will interact with the The aggregate of activated silica reacts to generate expansive sodium silicate, which damages the cement and concrete structures, greatly reduces the durability of the building, and is extremely dangerous. Therefore, the ratio of red mud in cement raw materials is received Great limitations, the idea of ​​mixing cement from red mud on a large scale often cannot be applied industrially

[0006] In addition, the use of red mud in the industry often focuses on how to use the washed red mud. For the washing water in the process, at most, the washing water is used multiple times and washed repeatedly, and the materials and heat in the system are not utilized. Deeper, more comprehensive and more systematic thinking

Images