Drying and calcining process and device for coproduction of sulfuric acid and cement from gypsum

Abstract

The invention discloses a drying and calcining process for coproduction of sulfuric acid and cement from gypsum. The process comprises the following steps of: before feeding raw materials containing the gypsum, a reducing agent and auxiliary materials into a firing system, completely removing physical water and crystal water from the raw materials; and obtaining acid-making smoke containing SO2 and cement clinker by using the firing system. The invention also discloses a drying and calcining device for coproduction of the sulfuric acid and the cement from the gypsum, which applies the process. The drying and dehydrating process of the gypsum is transferred from a preheater system or a rotary kiln in the past to a drying and dehydrating device, so that heat consumed by dehydration of the gypsum is separated from heat consumption of the firing system, and the amount of waste gas generated by combustion of fuel required by heat generation in the firing system is reduced; and water vapor formed by dehydration cannot be mixed with smoke for preparing the sulfuric acid, so the SO2 concentration of the smoke can be increased and the favorable condition is created for the subsequent preparation process of the sulfuric acid.

Description

technical field [0001] The invention belongs to the technical field of sulfuric acid co-production cement from gypsum, and relates to a high-efficiency and energy-saving drying and calcining process and device for sulfuric acid co-production cement from gypsum. Background technique [0002] The co-production of cement technology from gypsum to sulfuric acid was invented by the Germans during the First World War, and a device with a daily production of 40 tons of sulfuric acid was built in Germany at that time. The development and research of using phosphogypsum as raw material to produce sulfuric acid and cement began in the 1960s. The Austrian Linz Chemical Company built the first factory that used phosphogypsum to produce sulfuric acid and co-produced cement in 1968, with a daily output of 350 tons of sulfuric acid. . In order to improve the thermal efficiency of the process, Linz Company installed a counter-flow heat exchanger at the gas outlet of the rotary kiln to redu...

AI Technical Summary

Problems solved by technology

In this process, the raw material gypsum is mostly dihydrate gypsum, and a few processes are hemihydrate gypsum. The remaining crystal water and a small amount of physical water in the raw meal all enter the firing system, which not only increases the water vapor volume of the system, but also increases reduce the fuel consumption of the firing system, and then increase the flue gas volume of the system, resulting in SO 2 The concentration is reduced; and too much moisture will reduce the dew point temperature of the flue gas, which is not good for the operation of the equipment

In addition, the current process does not recycle the waste heat of the flue gas from the preheater system, and the heat consumption of the system is relatively high

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