Thermal technology for making acid from gypsum as well as device

Abstract

The invention discloses a thermal technology for making acid from gypsum. According to the thermal technology, a raw gypsum material which does not contain a reducing agent is dried and dehydrated by a dehydration furnace firstly, the raw material after drying and dehydration is preheated by a multi-level preheater, at least part of the preheated raw material is fed into a prereduction furnace, and the residual part is fed into a rotary kiln; the prereduction furnace reduces 20%-35% calcium sulfate into calcium sulfide, a hot raw material discharged from the prereduction furnace is fed into the rotary kiln, calcium sulfide and calcium sulfate react in the rotary kiln to generate sulfur dioxide and calcium oxide, sulfur dioxide enters an acid making procedure along with flue gas exhausted from the rotary kiln, calcium oxide and other components in the raw gypsum material are calcined into cement clinker in the rotary kiln and then discharged from the kiln, and the cement clinker is cooled and output. The invention further discloses a device for applying the thermal technology. Heat consumption of a gypsum acid-making system is reduced, the use amount of the reducing agent is reduced, the quality of clinker is improved, and the concentration of sulfur dioxide in the acid-making flue gas is increased, so that the investment and operation costs of a flue gas acid-making system are reduced.

Description

technical field [0001] The invention belongs to the technical field of gypsum sulfuric acid co-production cement, in particular to a thermal process and device for gypsum acid production. Background technique [0002] At present, the annual discharge of phosphogypsum in my country has exceeded 50 million tons (accumulative stacking of more than 250 million tons), the annual discharge of desulfurized gypsum has reached 30 million tons, and the annual discharge of salt gypsum is more than 5 million tons. With the development of phosphate compound fertilizer, electric power and sea salt industry, it will continue to increase. Industrial gypsum generally contains harmful substances. Long-term stacking not only takes up a lot of land, but also easily causes environmental pollution. Its comprehensive utilization is imminent. Gypsum sulfuric acid co-production cement technology can not only dispose of industrial waste such as phosphogypsum, desulfurized gypsum, and salt gypsum in l...

AI Technical Summary

Problems solved by technology

[0005] However, even the existing advanced gypsum sulfuric acid co-production cement technology generally has the following problems: 1) Gypsum uses coke or coal as a reducing agent, and the theoretical carbon-sulfur molar ratio is 0.5, but considering that part of the reduction in the firing system The agent will be burned and lost, so the molar ratio of carbon to sulfur should be increased to 0.65-0.8 in the actual batching, and the coke or coal added in excess will increase the cost

2) In order to prevent the reducing agent from being burned in the preheater system and cause skin blockage, the temperature of the material in the preheater system must be strictly controlled below 650°C, so the number of preheater stages in the gypsum acid production line is only four at most. stage, and often operate according to the third stage, resulting in high temperature of the flue gas exiting the preheater and large heat consumption of the system

3) The decomposition of gypsum and the sintering of clinker are both completed in the rotary kiln, while the decomposition of gypsum requires a reducing atmosphere, and the sintering of clinker requires an oxidizing atmosphere. Increasing the decomposition rate of gypsum is also not conducive to improving the quality of clinker

4) The heat consumption of gypsum dehydration and decomposition is large, resulting in a large amount of combustion flue gas, and the amount of flue gas generated by the combustion of excess reducing agent and the CO generated by the reaction of reducing agent and gypsum 2 All enter into the flue gas of the acid plant, so that the SO in the flue gas of the acid plant 2 The concentration is low, which increases the investment and operating costs of the flue gas acid making system

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