Process for recycling alkali and synchronously producing cement by roasting red mud

Abstract

The invention discloses a process for recycling alkali and synchronously producing cement by roasting red mud, belonging to the field of aluminum industry production. 1.2-2.1 tons of red mud as a byproduct is produced while 1 ton of aluminum oxide is produced, wherein the red mud contains 5-7% of alkali which is large in amount and harmful to the environment; and the alkali is a significant environmental pollution source for restraining the development of the aluminum industry and the comprehensive utilization of the red mud and damaging the ecological environment. At present, removing and recycling of the alkali in the red mud is still a difficult problem in the world. The invention solves the problem on removing and recycling the alkali in the red mud, and realizes that the cement is synchronously produced while the alkali is removed and recycled; therefore, the zero emission of solid waste residuals is realized for aluminum oxide production enterprises. The process is crucially characterized in that a condition of oxygen-free strong reduction is created for separating the alkali in the red mud, thereby a reducing/decomposing reaction of Na2O(solid)+C(solid)=2Na(gas)+CO(gas) can be performed successfully. According to the process provided by the invention, the red mud is indirectly heated and is decomposed under an air-insulated and oxygen-free strong reduction condition to generate Na metal atoms; and the Na metal atoms are led to the outside of the furnace together with a byproduct CO, and enter a recycling tower to synthesize alkali (NaOH) with water. After the alkali is separated and recycled, the residues are synchronously sintered into cement.

Description

Technical field: [0001] In the field of aluminum industry, a large amount of waste is produced when the raw material of electrolytic aluminum—alumina is produced, because it contains about 10% Fe 2 o 3 And it is red, so it is called red mud, which is the object of the present invention. Therefore this patent should be included in the field of aluminum industry science and technology. Background technique: [0002] Red mud contains 5% to 7% alkali, mainly where NaOH is piled up, where there is no vegetation, and alkali seeps into the ground with rainwater, destroying the groundwater system, and causing fish and shrimp to disappear when it flows into rivers. The amount of red mud is large, which is 1.5 to 2.1 times that of alumina production. my country's current alumina production capacity has reached more than 36 million tons, and the amount of red mud has at least 50 million tons, which occupies a large amount of land. Due to the existence of alkali, the comprehensive u...

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