Method for producing sulfur dioxide from calcium sulfate and sulfur

Abstract

The invention provides a method for producing sulfur dioxide from calcium sulfate and sulfur and relates to a chemical production process for producing sulfuric acid and cement clinker by adopting calcium sulfate. The method comprises the following steps: a, drying wet calcium sulfate into semi-hydrated gypsum, mixing other correction raw materials into the semi-hydrated gypsum to prepare a raw material, adding the raw material into a material preheating system consisting of multiple stages of cyclone preheaters, preheating, and then feeding into a reduction furnace; b, spraying liquid sulfur into the reduction furnace; c, controlling the content of oxygen in the reduction furnace to be less than 1.5%, and reducing calcium sulfate to generate calcium sulfide; and d, controlling the molar ratio of calcium sulfide generated in the step c to unreacted calcium sulfate to be (1:2)-(9:1), feeding a mixture of calcium sulfide and unreacted calcium sulfate into a rotary kiln and then reacting at oxidation atmosphere at the temperature of 900-1450 DEG C so as to obtain SO2 and the cement clinker. The method is rapid in reaction speed (the reaction time is only few seconds under fluidization), high in heat utilization rate, simple in process, and easily controllable in reaction condition.

Description

technical field [0001] The invention relates to a chemical 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 disposal will have an 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 phosphogypsum for many years. 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 the technology itself, in production There are still a lot of problems in the actual promotion and application. From the perspective of foreign countries, as e...

AI Technical Summary

Problems solved by technology

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 present situation of production, the existing devices are not very ideal, mainly reflected in the following aspects: 1. the existing production mode is to directly decompose calcium sulfate into SO under a weak oxidizing atmosphere or a reduction-oxidizing double atmosphere. 2 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 all 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, and the produced SO 2 When entering the converter, the concentration is only 3-6%. Compared with the sulfuric acid plant, the production capacity is reduced, and the operation and management are difficult.

3. It is difficult to realize large-scale production

At the same time, the generated calcium sulfide block needs to be ground and then mixed evenly with phosphogypsum, and roasted at 1000-1400°C for 0.5-3 hours in a non-oxidizing atmosphere. In order to meet the requirements of calcium sulfide grinding and uniform mixing with phosphogypsum, The production can only be carried out intermittently, the calcium sulfide has the problem of secondary heating, and the heat utilization rate is low

Moreover, the sulfur carried in the calcium sulfide cannot be burned in a non-oxidizing atmosphere, and will recondense into solids when it enters the sulfuric acid purification system, which will easily cause equipment blockage and reduce the utilization rate of sulfur

At the same time, the reaction should be carried out in a non-oxidizing atmosphere, the control is complicated, and it affects the complete combustion of the fuel

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