Process for producing sulfate acid from gypsum

Abstract

A method for producing sulfuric acid from gypsum comprises the steps of crushing gypsum, clay, coke and auxiliary materials, homogenizing, preheating in a three-stage preheater, calcinating in a rotary kiln while introducing oxygen-enriched air to obtain SO2 gas and clinker, feeding the SO2 gas into a sulfuric acid system for sulfuric acid production, and cooling the clinker with a cooling machine and feeding into a cement system for cement production. The inventive method designs raw material ratio, etc. with the focus of sulfuric acid production through the steps of preheating with the three-stage preheater and introducing oxygen-enriched air to produce sulfuric acid; and has the advantages of reduced calcination difficulty, remarkably increased sulfuric acid yield, remarkably reduced production cost, remarkably reduced calcination heat consumption, and distinct environmental and economic benefits. Also, the tail gas emission comes up to standards.

Description

technical field [0001] The invention relates to a technology for producing sulfuric acid from waste residue phosphogypsum or natural gypsum or flue gas desulfurization gypsum or a mixture of several kinds of gypsum in the phosphate fertilizer industry. It belongs to the technical field of sulfuric acid production. A production method for producing sulfuric acid from flue gas desulfurization gypsum or a mixture of several gypsums and by-product cement. Background technique [0002] my country is a large agricultural country lacking in sulfur resources. Phosphate fertilizer production accounts for more than 70% of sulfuric acid consumption, sulfuric acid with sulfur as raw material accounts for 50% of the total sulfuric acid output, and more than 95% of sulfuric acid raw materials come from imports, plus my country's dependence on foreign sulfur resources for imported sulfuric acid exceeds 55%. Recently, the price of sulfur has skyrocketed and remained high. Using gypsum as r...

AI Technical Summary

Problems solved by technology

[0003] my country's phosphate rock resources are abundant but not rich. With the extensive use of rich ore, the depletion of phosphate rock is becoming more and more serious. P 2 o 5 The content is generally less than 30%, SiO 2 The content is higher than 12%, resulting in poor quality phosphogypsum residue generated in the production of phosphoric acid, making the phosphogypsum residue unusable

It has long been reported that the poor quality of phosphogypsum waste residue made the unit unable to operate

The grades of natural gypsum in mineral deposits vary greatly, most of SiO 2 High content (essentially mixed with a certain amount of soil), which affects the utilization of natural gypsum

[0004] The original method of making sulfuric acid from gypsum has strict requirements on the raw material phosphogypsum or natural gypsum, such as gypsum P 2 o 5 Content less than 1.0%, SiO 2 If the content is less than 5.5%, the raw meal rate index is too heavy on cement production, resulting in high calcination temperature and large fuel consumption, so it enters the sulfuric acid system SO 2 Low gas concentration, SO 2 It is difficult to achieve self-heating balance in the conversion, so that the hanging electric furnace maintains production, and at the same time, the low oxygen-sulfur ratio makes SO 2 The conversion rate cannot be improved, and the SO in the exhaust gas 2 Concentration exceeding the standard

At the same time, the output of sulfuric acid and cement is low, the investment in plant construction is high, the production cost increases, and the economic benefit is poor, which seriously restricts the development of sulfuric acid from gypsum

Images