Ammonia-chemical-chain-cycle-based carbon dioxide capture and conversion method

Abstract

The invention discloses an ammonia recycling method, which belongs to the technical field of steel smelting technologies. The ammonia recycling method comprises the following steps of: absorbing carbon dioxide in flue gas produced in the steel production process through gas-liquid contact of aqueous solution of ammonia in an absorption tower to obtain ammonium bicarbonate or ammonium carbonate; performing extraction treatment on alkaline steel slag by adopting solution of ammonium chloride to obtain solution of calcium chloride or magnesium chloride and ammonia, recovering the ammonia to obtain ammonia water for capturing carbon dioxide, and reacting the solution of calcium chloride or magnesium chloride with the ammonium bicarbonate or the ammonium carbonate to obtain calcium carbonate or basic magnesium carbonate; and finally separating the solution of ammonium chloride for circular extraction of the alkaline steel slag. By the ammonia recycling method, the emission of the carbon dioxide can be reduced and the carbon dioxide is immobilized in the form of calcium carbonate or magnesium carbonate; meanwhile, calcium and magnesium oxides in steelmaking waste slag are recycled, NH3 generated in the whole process flow is circularly used, and the cost is reduced.

Description

technical field [0001] The invention relates to a carbon dioxide emission reduction method in the iron and steel production process, in particular to a carbon dioxide capture and conversion method based on ammonia chemical chain cycle. Background technique [0002] The phenomenon of global warming caused by greenhouse gases produced by burning fossil fuels has been recognized as a global environmental problem. Since 2007, my country's total carbon dioxide emissions have surpassed that of the United States, becoming the world's largest carbon dioxide emitter. It is estimated that by 2020, my country's carbon dioxide emissions will increase by more than 1.3 times on the basis of 2000. This increase is higher than that of the world. The increase in total emissions from 1990 to 2001 was even greater, which has seriously affected my country's international image. According to the statistics of the China Iron and Steel Industry Association, China's current steel output ranks first...

AI Technical Summary

Problems solved by technology

However, using ammonia water to absorb CO in flue gas 2 Emission reduction has the following disadvantages: firstly, the method needs to consume a large amount of ammonia; secondly, the produced NH 4 HCO 3 Although it can be used as an agricultural fertilizer, NH 4 HCO 3 Unstable, easy to decompose and volatilize, resulting in the captured carbon dioxide in NH 4 HCO 3 Re-released into the atmosphere when used as fertilizer (Kim et al., Energy Procedia, 2009 757-762.)

However, due to the low activity of alkaline substances in the dry steel slag, it is difficult to directly capture the carbon dioxide in the flue gas, and the energy consumption required for the process is also high (Dong Xiaodan, "Steelmaking", 2008: 29-32)

Even if the steel slag is humidified, its ability to directly capture carbon dioxide is very small, and the products of alkaline substances that absorb carbon dioxide are mixed with the slag, and the obtained carbonation products cannot be recovered

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