Method for producing sulfur dioxide from calcium sulfate and sulfur

A technology of sulfur dioxide and calcium sulfate, used in chemical instruments and methods, cement production, sulfur compounds, etc., can solve the problems of poor stability, difficult to achieve, poor heat transfer effect, and affecting the complete combustion of fuel.

Active Publication Date: 2012-06-20
YUNNAN YUNTIANHUA
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  • Summary
  • Abstract
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  • Claims
  • Application Information

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

Method used

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  • Method for producing sulfur dioxide from calcium sulfate and sulfur
  • Method for producing sulfur dioxide from calcium sulfate and sulfur

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] as attached figure 1 As shown, the phosphogypsum piled up in the slag yard obtained in the production of wet-process phosphoric acid, such as phosphogypsum containing 9-13% of external moisture, is added to the rotary hammer dryer and crusher commonly used in clinker firing in cement plants. The hot flue gas is subjected to heat exchange, dried into hemihydrate gypsum, mixed with pyrite slag, bauxite, and fly ash, and prepared into three rate values: KH=0.86—0.98, SM=1.8—4.0, IM =1.0—3.5 The gypsum raw meal is stored in the silo 1, the gypsum raw meal is measured by the weighing scale 2 and enters the four-stage cyclone preheater 3-6, and exchanges heat with the gas containing sulfur dioxide from the reduction furnace 7 and the rotary kiln 8, After being separated by the second cyclone preheater 5 counted from bottom to top, the material temperature rises to 600-950°C and enters the reduction furnace 7. The liquid sulfur is sprayed into the reduction furnace from the ...

Embodiment 2

[0032] When it is necessary to increase the reduction rate and heat capacity of calcium sulfate in the reduction furnace to improve the stability of the reduction system, the calcium sulfide and unreacted calcium sulfate mixture separated by the cyclone preheater 6 can be divided into two parts by the distributor 14. Part, wherein 50-70% of the material enters the reduction furnace, and the other 50-30% of the material enters in the rotary kiln, and the others are the same as the implementation example 1.

Embodiment 3

[0034] When using anhydrite as a raw material, because the anhydrite has less water content, it does not need to be dried, and it can be directly mixed and ground with the calibration raw material to obtain a gypsum raw meal, which is added to the system of Example 1. At this time, due to the total The moisture is low, in order to reduce the gas temperature of the cyclone preheater and improve the heat utilization rate, the number of stages of the cyclone preheater can be increased to 5-6. Others are the same as implementation example 1.

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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...

Claims

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Application Information

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IPC IPC(8): C01B17/50C04B7/24
CPCY02P20/10Y02P40/10
Inventor 明大增李英翔张应虎李天荣
Owner YUNNAN YUNTIANHUA
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