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A method for treating magnesium sulfate and magnesium sulfite wastewater by lime method

A technology of magnesium sulfite and magnesium sulfate, applied in separation methods, chemical instruments and methods, calcium/strontium/barium sulfate, etc., can solve the problems of high cost and high energy consumption, and achieve improved product purity and high separation efficiency , The effect of large separation coefficient of calcium and magnesium

Active Publication Date: 2017-12-15
TIANJIN SEA WATER DESALINATION & COMPLEX UTILIZATION INST STATE OCEANOGRAPHI
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Aiming at the problems of high energy consumption and high cost in the current magnesium sulfate and magnesium sulfite wastewater treatment methods, the present invention provides a lime method treatment process

Method used

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  • A method for treating magnesium sulfate and magnesium sulfite wastewater by lime method
  • A method for treating magnesium sulfate and magnesium sulfite wastewater by lime method

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Experimental program
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Effect test

Embodiment 1

[0038] The waste liquid after flue gas desulfurization in power plants is placed in a settler to settle and purify to remove insoluble matter. Pump the supernatant of the settler into the filter for filtration, analyze the composition after aeration treatment: Mg 2+ Content 2.04mol / L, SO 4 2- The content is 2.02mol / L; the concentration of calcium hydroxide in the lime slurry is 1mol / L.

[0039] The above-mentioned purified magnesium sulfate waste liquid and lime slurry are continuously added to the reaction crystallizer simultaneously by waste water inlet 11 and lime slurry inlet 12 respectively, and the feed rate of regulating purified magnesium sulfate waste liquid and lime slurry is respectively 2.4m 3 / h and 4.9m 3 / h. When the feed liquid level in the reaction crystallizer exceeds the upper opening of the circulation lifting device 6, the circulation lifting device 6 is opened, and the circulation liquid lifting flow rate of the circulation lifting device 6 is 80m 3 ...

Embodiment 2

[0042]Take magnesium sulfate underground brine and place it in a settler to settle, purify and remove insoluble matter. Pump the supernatant of the settler into the filter and analyze the composition after filtration: Mg 2+ Content 0.21mol / L, SO 4 2- Content 0.16mol / L, Cl - Content 0.14mol / L, Ca 2+ The content is 0.02mol / L; the concentration of calcium hydroxide in lime slurry is 0.25mol / L.

[0043] The above-mentioned purified magnesium sulfate waste liquid and lime slurry are continuously added to the reaction crystallizer simultaneously by waste water inlet 11 and lime slurry inlet 12 respectively, and the feed rate of regulating purified magnesium sulfate waste liquid and lime slurry is respectively 10.2m 3 / h and 8.0m 3 / h. When the feed liquid level in the reaction crystallizer exceeds the upper opening of the circulation lifting device 6, the circulation lifting device 6 is opened, and the circulation liquid lifting flow rate of the circulation lifting device 6 is...

Embodiment 3

[0046] Wastewater from a factory, main component: Mg 2+ Content 1.23mol / L, SO 3 2- Content 1.02mol / L, SO 4 2- The content is 0.20mol / L; the waste water is settled in a settler to purify and remove insoluble matter. Pump the supernatant of the settler into the filter for filtration, and prepare the lime slurry with a calcium hydroxide concentration of 1.6mol / L.

[0047] The above-mentioned purified magnesium sulfate waste liquid and lime slurry are continuously added to the reaction crystallizer simultaneously by waste water inlet 11 and lime slurry inlet 12 respectively, and the feed rate of regulating purified magnesium sulfate waste liquid and lime slurry is respectively 10m 3 / h and 6.8m 3 / h. When the feed liquid level in the reaction crystallizer exceeds the upper opening of the circulation lifting device 6, the circulation lifting device 6 is opened, and the circulation liquid lifting flow rate of the circulation lifting device 6 is 160m 3 / h, overflow speed 0.2m / ...

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Abstract

The invention discloses a method for treating magnesium sulfate and magnesium sulfite wastewater by virtue of a lime method. Technical steps comprise settling purification, aeration oxidization, reactive crystallization separation, overflow liquid filtering, washing and drying, kettle-bottom slurry washing and separation and filtered stock recycling. Purified and oxidized wastewater and lime slurry are continuously added into a reaction crystallizer respectively, and a reactive crystallization condition is controlled to bond sulfate ions and calcium ions to form and settle calcium sulfate dihydrate crystals with larger particle sizes at the bottom of the reactive crystallizer and bond magnesium ions and hydroxide ions to form magnesium hydroxide with smaller particle sizes to continuously overflow from an overflow opening of the reactive crystallizer. The method has the characteristics of simple procedures, high separation efficiency, low equipment investment and running cost and the like, and can be used for treating magnesium sulfate and magnesium sulfite wastewater in large batches. Reaction products can be used for preparing high-quality magnesium hydroxide and calcium sulfate dihydrate for selling as chemical products; reaction mother liquor can be used as process water instead of fresh water, so that zero emission of magnesium sulfate and magnesium sulfite wastewater can be implemented.

Description

technical field [0001] The invention relates to wastewater treatment technology, in particular to a method for preparing magnesium hydroxide and calcium sulfate dihydrate by treating magnesium sulfate and magnesium sulfite wastewater with a lime method. Background technique [0002] In recent years, due to its advantages of high desulfurization efficiency, simple process, and low investment costs, magnesium desulfurization technology has been widely used in areas with abundant magnesium sources. It has achieved the removal of sulfur dioxide in the exhaust gas of coal-fired boilers. Make coal-fired boiler flue gas meet emission standards. At the same time, the desulfurization method produces a large amount of waste water containing desulfurization by-products such as magnesium sulfate and magnesium sulfite. With the increasingly stringent national regulations on wastewater discharge and the implementation of the "energy saving and emission reduction" strategy, the treatment ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01F5/22C01F11/46B01D9/02
CPCB01D9/00C01F5/22C01F11/46
Inventor 赵旭王涛张琦路绍琰王亮王泽江黄西平
Owner TIANJIN SEA WATER DESALINATION & COMPLEX UTILIZATION INST STATE OCEANOGRAPHI
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