Process for producing sulfur and light calcium carbonate from phosphorus gypsum

Abstract

The invention provides a process for producing sulfur and light calcium carbonate from phosphorus gypsum. The process includes mixing phosphorus gypsum and coal at molar ratio of 1:(2-3) to obtain a mixture, adding plasticizer 1-5 wt% of the mixture and appropriate amount of water, stirring, forming into hollow blocks with a press or extruder, stacking on a kiln car by a stacker or mechanical arm, drying in a tunnel drying chamber, performing reduction calcination in a tunnel kiln to convert phosphorus gypsum into calcium sulfide and release carbon dioxide, crushing and pulverizing calcium sulfide and sending to leaching process, reacting under action of water and hydrogen sulfide to obtain calcium hydrosulfide solution, filtering to remove impurities, introducing carbon dioxide into the calcium hydrosulfide solution to perform displacement reaction and generate light calcium carbonate and hydrogen sulfide gas, drying the light calcium carbonate to obtain product, returning partial hydrogen sulfide gas to the leaching process, and producing sulfur from the rest of hydrogen sulfide gas by wet absorption oxidation method. The process has the advantages of low investment, low production cost, high sulfur conversion rate above 95%, and cyclic resource utilization.

Description

technical field [0001] This aspect relates to the technical field of chemical production, in particular to a process for producing sulfur and light calcium carbonate from phosphogypsum. Background technique [0002] Phosphogypsum is the waste residue discharged from the industrial production of wet-process phosphoric acid and phosphate fertilizer. The production of one ton of phosphoric acid will produce about five tons of phosphogypsum waste residue. The production of phosphate fertilizer in my country will discharge tens of millions of tons of phosphogypsum every year. Such a huge waste residue requires a large amount of land to be piled up, and at the same time causes serious pollution to the environment. [0003] In the prior art, some propose to roast phosphogypsum with a converter, and some propose to roast and decompose phosphogypsum with a fluidized fluidized furnace, but neither can achieve the desired effect. The main reason is that the above kilns cannot meet th...

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Problems solved by technology

Such a huge waste residue requires a large amount of land to be piled up, and at the same time causes serious pollution to the environment

[0003] In the prior art, some propose to use a converter to roast phosphogypsum, and some propose to use a fluidized bed furnace to roast and decompose phosphogypsum, but none of them can achieve the desired effect.

The main reason is that the above kilns cannot meet the requirements of reduction and decomposition of phosphogypsum in terms of temperature, atmosphere, holding time and other factors, so the conversion rate of sulfur is low and industrial production cannot be carried out.

There are also patents that put the material in the sagger and roast it in a tunnel kiln or a wheel kiln. This method has low thermal efficiency, high energy consumption, and high replacement cost of the sagger. All these make the cost of producing calcium sulfide too high to be popularized. to production

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