Phosphogypsum processing method

Abstract

The invention relates to a phosphogypsum processing method. The method is characterized in that: active magnesium oxide is carbonized for 0.5-2h by using carbon dioxide under a temperature of 20-40 DEG C in a carbonization tower; solid-liquid separation is carried out, such that liquid-phase heavy magnesium water is obtained; phosphogypsum and the heavy magnesium water are subjected to a metathesis reaction for 0.5-2h under a temperature of 20-60 DEG C; solid-liquid separation is carried out, such that a liquid-phase magnesium sulfate solution is obtained, wherein the ratio of the amount of sulfate in phosphogypsum to the amount of magnesium ion in the heavy magnesium water is that SO4<2->:Mg<2+>=1-2:1; the magnesium sulfate solution is subjected to evaporation crystallization, such that magnesium sulfate heptahydrate crystals are obtained; the magnesium sulfate heptahydrate crystals are subjected to reduction thermal decomposition under a temperature of 600-900 DEG C by using carbon monoxide with a 1.2-2 time molar amount, such that sulfur dioxide and high-purity magnesium oxide are obtained. Raw materials adopted by the invention are sourced from industrial waste slag or industrial tail gas. The processing process is simple, no pollution is caused, preparation efficiency is high, cost is low, and good economic benefit is provided. The method is an ideal industrial waste recycling method.

Description

technical field [0001] The invention relates to a processing method of phosphogypsum, which belongs to the field of phosphorus chemical industry. This processing method is mainly used for the reuse of phosphogypsum, the production of magnesium sulfate and the production of high-purity magnesium oxide. Background technique [0002] Phosphogypsum is a kind of solid waste produced in the process of wet phosphate fertilizer production. It mainly contains gypsum, phosphorus, fluorine, silicon dioxide and a certain amount of water, and it is easy to cause environmental pollution during the stacking process. There are nearly 20 million tons of phosphogypsum discharged in my country every year, and more than 100 million tons have been stockpiled over the years. At present, there are many plans for the utilization of phosphogypsum, such as building materials and the production of ammonium sulfate. However, due to the relatively concentrated distribution of phosphogypsum and the sma...

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Problems solved by technology

Sichuan University Master Thesis, 2004), Potassium Sulfate (Liu Daijun, Li Jun, Zhong Benhe, Zhang Yunxiang. A new process for producing potassium sulfate by phosphogypsum conversion method [J]. Phosphate Fertilizer and Compound Fertilizer, 1996, 3: 17-19), etc. , but it is used to prepare magnesium sulfate, especially the method for preparing magnesium sulfate in combination with carbon dioxide tail gas has not been reported

[0009]In summary, regarding the use of carbon dioxide generated in the production process of calcium feed to carbonize active magnesium oxide to process phosphogypsum to prepare magnesium sulfate and use yellow phosphorus tail gas to reduce magnesium sulfate to prepare high The technical scheme of pure magnesium oxide has not been reported yet

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