Improved production process for preparing sulfuric acid and cement from gypsum

Abstract

The invention relates to an improved production process for preparing sulfuric acid and cement from gypsum. Raw materials comprise dihydrate gypsum, clay and a reducing agent. The process comprises the following steps of: drying the raw materials; independently grinding; mechanically stirring and homogenizing; preheating green stock; decomposing and calcining through a rotary kiln; acid-washing and purifying kiln gas; drying through SO2; performing a double-conversion double-absorption process; and grinding the cement to prepare sulfuric acid and cement products, wherein a dihydrate gypsum process is adopted; the raw materials are dried by absolute dry tail gas at the temperature of between 70 and 85 DEG C which is discharged out of a sulfuric acid absorption device to obtain the dihydrate gypsum with free water content of less than 5 weight percent; and the dihydrate gypsum is then directly homogenized with the clay and the reducing agent in the presence of CaCl2 or Na2SO4 to produce the green stock. In the process, the heat consumption is reduced by 30 percent, the power consumption is reduced by 20 percent, the investment is reduced by 25 to 40 percent, and the cost is reduced by 25 to 30 percent. The process overcomes the disadvantages of high power consumption and heat consumption, large investment, low operation ratio and the like in the conventional method, 0.4 to 0.5 tonnage of steam serving as a byproduct is produced by every tonnage of sulfuric acid, and the process has obvious economic benefit.

Description

technical field [0001] The invention relates to a process for producing sulfuric acid and cement from gypsum, and belongs to the field of comprehensive utilization of sulfuric acid and cement industry production technology and industrial by-product gypsum waste residue resources and environmental protection and treatment. Background technique [0002] The research on gypsum sulfuric acid and cement technology began in the early 20th century. In 1916, Germany's Muller and Kuhne (Muller Kuhne) successfully developed natural gypsum to produce sulfuric acid and cement technology, and established a pilot plant; thereafter, Britain, Germany, Poland, Austria, South Africa, etc. successively built the following Natural gypsum, anhydrite and phosphogypsum are used as raw materials to produce sulfuric acid and cement plant, and put into production. The average daily production capacity of sulfuric acid and cement is 160 tons each. Due to large investment, high heat consumption, low o...

AI Technical Summary

Problems solved by technology

However, each device has the disadvantages of high investment, large heat consumption, large power consumption, and poor economic benefits, so some of them have been discontinued.

For example, the application number is 200810139276.2, and the patent application titled an improved production process for the production of sulfuric acid and cement from gypsum uses a hemihydrate gypsum production process. Since the raw material is dihydrate gypsum, it needs to be heated to a high temperature above 160°C for drying to obtain hemihydrate. Gypsum has a large heat consumption and complicated equipment, and when this process is adopted, the rotary kiln is very easy to form rings, the operation rate is low, the investment is high, the heat consumption is large, the power consumption is large, and the economic benefit is poor.

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