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Phosphogypsum pretreatment and purification method

A phosphogypsum and pretreatment technology, applied in the field of phosphogypsum purification, can solve the problems of aggravating the loss of water-soluble phosphorus and fluorine, unable to build gypsum, environmental pollution, etc., and achieve the effects of reducing product consumption, prolonging the initial setting time, and reducing costs.

Inactive Publication Date: 2020-11-10
YUNNAN PHOSPHATE CHEM GROUP CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a pretreatment and purification method for phosphogypsum, which solves the problem that existing phosphogypsum relies on stockpiling to aggravate the loss of water-soluble phosphorus and fluorine, causes environmental pollution and cannot be used as building gypsum in a short period of time

Method used

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  • Phosphogypsum pretreatment and purification method

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Experimental program
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Effect test

Embodiment 1

[0023] After the phosphogypsum is unloaded into the slag hopper, use the phosphogypsum pretreated washing water and part of the filtrate to return to rinse and re-slurry. The gypsum slurry enters the gypsum re-slurry tank and stirs evenly to control the slurry concentration to 31%. The repulped slurry is pumped to the slurry distribution box of the belt filter and evenly distributed, and then dehydrated in the dehydration zone.

[0024] The vacuum degree of the filter is controlled by two vacuum pumps, the absolute pressure of the dehydration and washing area is 35kPa, and the absolute pressure of the other area is 30kPa.

[0025] Gypsum adopts two-stage countercurrent washing. The water in the washing tank is heated by steam, and the water temperature is 65°C. The washing water pump is sent to the secondary washing water distribution box to wash the gypsum evenly. The lotion after the second washing is pumped as the first-level gypsum. The washing water and the washing liquid...

Embodiment 2

[0029] After the phosphogypsum is unloaded into the slag hopper, use the phosphogypsum pretreated washing water and part of the filtrate to return to rinse and re-slurry. The gypsum slurry enters the gypsum re-slurry tank and stirs evenly to control the slurry concentration to 32%. The repulped slurry is pumped to the slurry distribution box of the belt filter and evenly distributed, and then dehydrated in the dehydration zone.

[0030] The vacuum degree of the filter is controlled by two vacuum pumps, the absolute pressure of the dehydration and washing area is 35kPa, and the absolute pressure of the other area is 30kPa.

[0031] Gypsum adopts two-stage countercurrent washing. The water in the washing tank is heated by steam, and the water temperature is 65°C. The washing water pump is sent to the secondary washing water distribution box to wash the gypsum evenly. The lotion after the second washing is pumped as the first-level gypsum. The washing water and the washing liquid...

Embodiment 3

[0035] After the phosphogypsum is unloaded into the slag hopper, use the phosphogypsum pretreated washing water and part of the filtrate to return to rinse and re-slurry. The gypsum slurry enters the gypsum re-slurry tank, stirs evenly, and controls the slurry concentration to 35%. The repulped slurry is pumped to the slurry distribution box of the belt filter and evenly distributed, and then dehydrated in the dehydration zone.

[0036] The vacuum degree of the filter is controlled by two vacuum pumps respectively, the absolute pressure of the dehydration and washing area is 31kPa, and the absolute pressure of the other area is 27kPa.

[0037] Gypsum adopts two-stage countercurrent washing. The water in the washing tank is heated by steam, and the water temperature is 70°C. The washing water pump is sent to the secondary washing water distribution box to wash the gypsum evenly. The lotion after the second washing is pumped as the first-level gypsum. The washing water and the w...

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Abstract

The invention discloses a phosphogypsum pretreatment and purification method, belonging to the technical field of phosphogypsum purification. The method comprises the following steps: washing slag discharged from a wet-process phosphoric acid production line with washing water for washing phosphogypsum and a filtrate in a slag hopper, and conducting repulping; pumping the repulped slurry into a slurry distribution box of a belt filter for uniform distribution; dehydrating the slurry, and then carrying out countercurrent washing twice; drying the washed phosphogypsum with a desiccant, and conducting blowing; and sending a filtrate obtained after repulping to a phosphoric acid production system for use. The phosphogypsum having been subjected to dehydration, washing and blowing has a water-soluble phosphorus content of less than or equal to 0.05%, a water-soluble fluorine content of less than or equal to 0.03%, a pH value of greater than or equal to 5 and a water content of less than orequal to 23%. The treated phosphogypsum can directly enter a building gypsum production area, so the stockpiling time is greatly shortened, the volume occupation of a slag bin is reduced, and the service life of the slag bin is favorably prolonged. The filtrate returns to a phosphoric acid production system for use, so the recovery rate of phosphorus is increased, and production consumption of phosphoric acid is reduced.

Description

technical field [0001] The invention relates to the technical field of phosphogypsum purification, in particular to a method for pretreatment and purification of phosphogypsum. Background technique [0002] Phosphogypsum is a by-product of wet-process phosphoric acid production. For every ton of phosphate rock consumed, about 1.5 tons of phosphogypsum are produced. The annual output of phosphogypsum in the country is as high as nearly 80 million tons, and the accumulated stockpiles of phosphogypsum exceed 600 million tons. , The land occupation is large, and the environmental protection and safety risks brought by stockpiling are relatively large. The utilization rate of phosphogypsum is low, and the storage cost of large quantities is high. [0003] The content of water-soluble phosphorus and fluorine in phosphogypsum is high. If it is used directly without treatment, the phosphogypsum needs to be stored naturally for more than one year. Phosphorus and fluorine also decre...

Claims

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Application Information

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IPC IPC(8): C04B11/032C04B11/00
CPCC04B11/032C04B11/005
Inventor 刘正东周琼波坝吉贵牛司江李键周波樊永林李杰韦朝安金斌杨海杨雄俊
Owner YUNNAN PHOSPHATE CHEM GROUP CORP
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