Method for preparation of belite sulphoaluminate cement and co-production of sulfuric acid by reducing gypsum with sulfur gas

Abstract

The invention relates to a method for the preparation of belite sulphoaluminate cement and the co-production of sulfuric acid by reducing gypsum with sulfur gas. According to the method, industrial byproduct gypsum is used as a main raw material; an alkalinity coefficient (C), an aluminum-sulfur ratio (P) and an aluminum-silicon ratio (N) are controlled according to the application requirements ofthe belite sulphoaluminate cement clinker; one or more of low-grade bauxite, coal ash, coal gangue, red mud, clay and iron slag are selected as ingredients, the gas sulfur is adopted as a reducing agent, so that the gypsum is promoted to be decomposed; and therefore, the belite sulphoaluminate cement is prepared, and meanwhile, high-concentration gas-phase SO2 flue gas is obtained and used for preparing sulfuric acid from follow-up flue gas. Compared with the prior art, the method can consume a large amount of industrial gypsum and save limestone and natural gypsum resources, meanwhile, can obtain high-quality belite sulphoaluminate cement and industrial sulfuric acid products; and the method has the advantages of simple process, high implementation performance of system control indexes,convenient operation and management, advanced process equipment, low device investment, low energy consumption, low operation cost and high automation degree.

Description

technical field [0001] The invention relates to building materials and chemical products, in particular to a method for producing belite sulfoaluminate cement by reducing raw material containing gypsum with sulfur gas to co-produce sulfuric acid. Background technique [0002] Sulphoaluminate cement has the advantages of low alkalinity, high early strength, micro-expansion, corrosion resistance and frost resistance, and is especially suitable for use in coastal and cold areas and emergency repair projects. Traditional sulphoaluminate cement is made of calcium sulphoaluminate by calcining limestone, bauxite and gypsum at high temperature (1200-1350°C). Dicalcium silicate (C 2 S) is the main mineral phase composition, and then mixed with a small amount of gypsum and ground to obtain sulphoaluminate cement products. Compared with ordinary Portland cement, due to the reduction in the amount of raw material limestone, the firing temperature is also 100-150°C lower than that of ...

AI Technical Summary

Problems solved by technology

At present, the annual output of desulfurized gypsum in my country is about 80 million tons, and the comprehensive utilization rate is about 83%; the annual output of phosphogypsum is about 80 million tons, and the comprehensive utilization rate is less than 40%; other by-product gypsum is about 25 million tons, and the comprehensive utilization rate is about 40%.

The purpose of the above-mentioned inventive method is to maximize the utilization of industrial by-product gypsum as calcium and sulfur raw materials, provide a good idea for the resource utilization of industrial by-product gypsum, and can get through in the process; but the above methods mostly use activated carbon or Solid coke or anthracite is used as a solid reducing agent, and gypsum, clay, high-quality bauxite, fly ash, iron slag, high-sulfur coal, etc. are calcined together to produce sulphoaluminate or belite sulphoaluminate cement clinker , carbon reduction generally has high investment energy consumption and high CO 2 Emissions, furnace gas SO 2 The concentration is low, the co-production of sulfuric acid is difficult for "two conversions and two absorptions", and the operation cost is high. There are problems in operation, environmental protection and economic cost.

[0010] There are also some patents or literature reports, using phosphogypsum or desulfurization gypsum or titanium gypsum and other industrial by-product gypsum and limestone together as the source of calcium and sulfur in cement ingredients, and other raw materials such as bauxite to configure the required cement raw materials. Calcination to produce sulphoaluminate cement clinker or belite sulphoaluminate cement clinker, these methods are a small part of the use of gypsum decomposition to replace a part of CaO in limestone, can not effectively use industrial waste gypsum on a large scale, calcination SO in flue gas 2 The concentration cannot reach the concentration requirements of conventional industrial production of sulfuric acid, and the SO 2 It also increases the burden of environmental protection

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