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Method for producing nitric acid and sodium nitrate by using nuclear-grade hafnium oxide production discharged wastewater

A hafnium dioxide and sodium nitrate technology, which is applied in the purification of nitrogen oxides/oxyacids, nitric acid, and alkali metal nitrates, can solve the problems of inability to recover nitric acid and consume large amounts of liquid alkali, and achieve full resource utilization and low cost Effects of low and obvious social and economic benefits

Pending Publication Date: 2022-04-05
中核二七二铀业有限责任公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] This method can only recover sodium nitrate in the raffinate, but cannot recover nitric acid, and needs to consume a large amount of liquid caustic

Method used

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  • Method for producing nitric acid and sodium nitrate by using nuclear-grade hafnium oxide production discharged wastewater

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] (1) The 195L raffinate produced by the enrichment of hafnium during the production of nuclear-grade hafnium dioxide was sampled and analyzed for a nitric acid concentration of 3.95mol / L; Na + The concentration is 49.75 (g / L), and it is transported to the preheater with a pump. After the feed liquid is preheated at 85°C, it enters the first-effect evaporator. The specific gravity of the concentrated solution is 1.265.

[0029] (2) The concentrate is pumped into the second-effect evaporation crystallizer, the temperature of the second-effect evaporation crystallizer is controlled at 80°C, the pressure is controlled at 12kpa for distillation and crystallization, and the second-effect distillate nitric acid is collected to obtain a concentration of 6.02mol / L Nitric acid 103L.

[0030] (3) The sodium nitrate particles evaporated and crystallized enter the centrifuge under the action of gravity and are washed once with the zirconium precipitation mother liquor with a solid-t...

Embodiment 2

[0032] (1) The 206L raffinate produced by the enrichment of hafnium during the production of nuclear-grade hafnium dioxide was sampled and analyzed for a nitric acid concentration of 3.93mol / L; Na + The concentration is 49.67 (g / L), and it is pumped to the preheater. After the feed liquid is preheated at 85°C, it enters the first-effect evaporator. The temperature of the first-effect evaporator is controlled at 115°C, and the pressure is controlled at 60kpa. The specific gravity of the concentrated solution is 1.261.

[0033] (2) The concentrated solution is pumped into the second-effect evaporation crystallizer, the temperature of the second-effect evaporation crystallizer is controlled at 75°C, the pressure is controlled at 10kpa for distillation and crystallization, and the second-effect distillate nitric acid is collected to obtain a concentration of 6.06mol / L Nitric acid 109L.

[0034] (3) The sodium nitrate particles evaporated and crystallized enter the centrifuge unde...

Embodiment 3

[0036] (1) The 200L raffinate produced by the enrichment of hafnium during the production of nuclear-grade hafnium dioxide was sampled and analyzed for the concentration of nitric acid to be 3.96mol / L; Na + Concentration is 49.73 (g / L), pumped to the preheater, the feed liquid is preheated at 85°C and enters the first-effect evaporator, the temperature of the first-effect evaporator is controlled at 120°C, and the pressure is controlled at 55kpa for distillation and concentration, concentrated to The specific gravity of the concentrated solution is 1.267.

[0037] (2) The concentrated solution is pumped into the second-effect evaporation crystallizer, the temperature of the second-effect evaporation crystallizer is controlled at 85°C, the pressure is controlled at 15kpa for distillation and crystallization, and the second-effect distillate nitric acid is collected to obtain a concentration of 6.10mol / L Nitric acid 105.5L.

[0038] (3) The sodium nitrate particles evaporated a...

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Abstract

The invention belongs to the technical field of radioactive waste utilization, and particularly relates to a method for producing nitric acid and sodium nitrate by using nuclear-grade hafnium oxide production discharged wastewater. The raffinate generated after extraction and enrichment of hafnium in the production process of nuclear-grade hafnium dioxide is used as feed liquid for producing nitric acid and sodium nitrate. Feeding the material liquid into a double-effect evaporation crystallizer for reduced pressure distillation, feeding the material liquid into a first-effect evaporator for distillation and concentration, feeding the concentrated liquid into a second-effect evaporator for distillation and crystallization, collecting second-effect distillate to obtain a nitric acid product, and filtering crystal mush by a centrifugal machine to obtain a sodium nitrate product. The method is simple in technological process, full in resource utilization and low in cost, the recovery rate of nitric acid in the raffinate can reach 80% or above, the recovery rate of sodium nitrate can reach 95% or above, the reduction amount of waste liquid is 90% or above, environment friendliness is achieved, and obvious social benefits and economic benefits are achieved.

Description

technical field [0001] The invention belongs to the technical field of radioactive waste utilization, and in particular relates to a method for producing nitric acid and sodium nitrate by using nuclear-grade hafnium dioxide production discharge wastewater. Background technique [0002] Hafnium enrichment is a key step in the production of nuclear-grade hafnium dioxide. The raffinate after extraction and separation of zirconium and hafnium is used as the original solution enriched with hafnium. After extraction by P204, raffinate water is produced. The raffinate water mainly contains nitric acid, sodium nitrate, a small amount of zirconium hafnium and metal impurities. The average concentration of nitric acid is 3.87mol / L, the average concentration of nitrate is 6.28mol / L and the average concentration of sodium ion is 2.31mol / L. A part of the raffinate is returned to the zirconium and hafnium extraction and separation system to prepare the raw liquid, and a part is treated ...

Claims

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Application Information

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IPC IPC(8): C01B21/46C01D9/16C01D9/18
Inventor 孙斌孙军孔冬成祝和彪
Owner 中核二七二铀业有限责任公司
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