Method for improving SO2 concentration in acid making technique with decomposition of calcium sulphate

Abstract

The invention relates to a method for improving the concentration of the SO2 in decomposing the calcium sulfate to acid craft and a chemical manufacturing technique of sulphuric acid and cement clinker, in particular to a manufacturing technique of sulphuric acid and cement clinker made from calcium sulfate. The procedures of the invention are as follows: a, under the function of the strong reduction medium, the calcium sulfate is produced into calcium vulcanization in the reactor; b, the reduction product of a procedure is the compound of the calcium vulcanization and the unreacted calcium sulfate; c, the reduction product is transferred to another reaction directly and under the high temperature, the calcium vulcanization and the calcium sulfate react and make into the SO2 and the clinker. The method has the advantages that: the concentration of the SO2 in gas is increased; the production system of sulfate is more stable and the extensive use of phosphogypsum is possible.

Description

technical field [0001] The invention relates to a chemical production process for sulfuric acid and cement clinker, in particular to a production process for producing sulfuric acid and cement clinker by using calcium sulfate. Background technique [0002] Phosphogypsum is the waste produced by decomposing phosphate rock with sulfuric acid in chemical production. Its quantity is huge, and improper treatment has a great impact on the environment. Most of it is buried in the world. Due to the lack of sulfur resources in my country, some people have been working on the development of phosphorus for many years. Gypsum co-production cement process, according to this process, the waste phosphogypsum produced in the production of phosphoric acid is used to produce cement and sulfuric acid, and sulfuric acid is used to produce phosphoric acid, repeated cycles, almost no waste, but due to the complexity of this technology itself, in There are still a lot of problems in the actual promo...

AI Technical Summary

Problems solved by technology

[0002]Phosphogypsum is the waste produced by decomposing phosphate rock with sulfuric acid in chemical production. Its quantity is huge, and improper treatment will have a great impact on the environment. Most of it is buried in the world Due to the lack of sulfur resources in our country, people have been working on the development of phosphogypsum co-production cement process for many years. According to this process, the waste phosphogypsum produced in the production of phosphoric acid is used to produce cement and sulfuric acid, and sulfuric acid is used to produce phosphoric acid. Repeated cycles, There is almost no waste, but due to the complexity of the technology itself, there are still a lot of problems in the actual promotion and application of production

Judging from the foreign situation, as early as 1916, there were examples of using hollow rotary kilns to produce cement and sulfuric acid abroad, but due to high heat consumption, this process has basically been eliminated. In the 1960s, with With the development of dry cement production technology, low heat consumption kiln tail preheating technology and low consumption and high efficiency kiln decomposition technology are widely used in the world to produce ordinary cement. Under this background, Linz Company in Austria developed a vertical cylinder The preheater is used as a heat exchange device. The raw material phosphogypsum is mixed with auxiliary raw materials after being dried once, and then enters the vertical preheater for preheating and then enters the kiln for decomposition and calcination. Compared with the original process, the heat consumption can be reduced, but due to Due to difficulties in production control and unstable SO2 content in the gas, the development is slow. At home and abroad, there has been strong interest in the new technology and process of phosphogypsum fluidized bed decomposition, and a lot of work has been done

The technology of gypsum decomposition and co-production of cement and sulfuric acid started relatively late in China. The current mature technology is to combine the dried powdery materials with other raw materials and grind them into the hollow rotary kiln for decomposition and calcination. The atmosphere in the kiln is difficult to control. It is easy to cause problems such as high oxygen content in the kiln, which will cause the carbon added in the raw material to partially react with oxygen, resulting in insufficient carbon required for the decomposition reaction of phosphogypsum, and the decomposition rate and desulfurization rate will be reduced.

In addition, the hollow rotary kiln has been eliminated in my country's cement industry due to its poor heat transfer effect and high coal consumption.

From the perspective of production status, the existing devices are not very ideal, mainly reflected in the following aspects: 1. The existing production methods are to directly decompose calcium sulfate into SO2 and calcium oxide, the actual decomposition temperature is above 1000°C, the life of the refractory material in the separation equipment is difficult to meet the requirements of industrialization, and the selection is difficult. So far, no industrialized decomposition device outside the kiln has been put into production

2. In the existing production process, the reduction, decomposition and oxidation of calcium sulfate are carried out in a decomposition furnace or kiln. The control of operating conditions is complicated, the stability is poor and difficult to achieve, and the heat consumption is large. The produced SO2 When entering the converter, the concentration is only 3-5%, which reduces the production capacity of the sulfuric acid unit, makes it difficult to guarantee the conversion temperature, and makes operation and management difficult

3. It is difficult to realize large-scale production

This makes the entire production control process more complicated and increases investment

At the same time, the method of adding sulfur to the raw material may also cause a reduction in the decomposition rate of calcium sulfate.

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