Method for Removing Sulfate from Wastewater

A sulfate and waste water technology, applied in calcium/strontium/barium sulfate, mining waste water treatment, energy waste water treatment, etc., can solve problems such as the influence of parameters not provided, and achieve low sulfate removal rate and reduced sulfate content Effect

Active Publication Date: 2021-03-12
METSO OUTOTEC (FINLAND) OY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the publication DE3709950 discloses that sodium aluminate can use Al(OH) 2 and sodium hydroxide, but it does not provide any suitable parameters about the method and their possible influence on the calcium vanadite precipitation method

Method used

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  • Method for Removing Sulfate from Wastewater
  • Method for Removing Sulfate from Wastewater
  • Method for Removing Sulfate from Wastewater

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach

[0072] According to one embodiment of the invention, the plant comprises means for carrying out the above-mentioned method steps.

[0073] According to one embodiment of the invention, the plant comprises a storage tank for storing the sodium aluminate before it is used in the wollastonite precipitation unit.

[0074] According to one embodiment of the invention, the plant comprises a gypsum precipitation unit a') preceding the calcium vanadite precipitation unit b) for precipitating gypsum by contacting waste water with a second calcium compound.

[0075] According to one embodiment of the invention, the plant comprises an optional gypsum removal unit a') between the gypsum precipitation unit a') and the wollastonite precipitation unit b). The gypsum removal unit is used for solid-liquid separation , to remove the precipitated gypsum from the slurry. Typically the gypsum removal unit is a clarifier. A flocculant is typically used to help the sediment settle in the clarifier. ...

Embodiment

[0106] Experiments for the preparation of sodium aluminate

[0107] An experimental set was carried out to investigate the preparation of sodium aluminate. Change two main variables: molar ratio NaOH:Al(OH) 3 (1-1.5, where >1 indicates a ratio exceeding the stoichiometric ratio) and reaction temperature (70-120°C). Due to the high boiling point of the sodium hydroxide solution, experiments can be performed at atmospheric pressure.

[0108] Table 1. Experimental setup

[0109] Na / Al-molar ratio Al(OH) 3 [g]

Reaction temperature [°C] Dilution water [g] EXP1 1.500 495 120 180 EXP2 1.500 495 70 180 EXP3 1.250 592 120 364 EXP4 1.250 592 95 364 EXP5 1.250 592 70 364 EXP6 1.000 740 120 646 EXP7 1.000 740 70 646 EXP8 1.375 540 107 265

[0110] experiment

[0111] Sodium hydroxide (50% solution, technical grade) was first heated up to 50°C. Add Al(OH) 3 .

[0112] After adding Al(OH...

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Abstract

The present invention relates to a method and apparatus for removing sulfate, calcium and / or other soluble metals from wastewater, wherein NaOH and Al(OH) 3 contact at a temperature of at least 60°C and in a molar ratio of NaOH:Al(OH) 3 is at least 1.0 for the preparation of sodium aluminate, the waste water is contacted with the obtained sodium aluminate and the first calcium compound to produce a slurry containing mayordite, and the slurry containing the mayardite is subjected to solid-liquid separation to separate the solid from the liquid, thereby producing a first solution, contacting the first solution with a carbonating agent, to neutralize the first solution and to precipitate calcium contained in the first solution as calcium carbonate, and to perform solid-liquid separation to The precipitated calcium carbonate is separated from the first solution to obtain water with reduced sulfate, calcium and / or other soluble metal content.

Description

[0001] field of invention [0002] The present invention relates to a method of removing sulfate, calcium and / or other soluble metals from wastewater, and more particularly to a method of removing sulfate, calcium and / or other soluble metals from wastewater using sodium aluminate. [0003] Background of the invention [0004] Sodium aluminate chemicals are required in the so-called wollastonite precipitation process, which is used to remove sulphate and calcium from water, especially from mining industrial wastewater. The wollastonite precipitation method is an effective method of removing sulfate from wastewater to levels far below that achievable using traditional gypsum precipitation methods. However, sodium aluminate can be expensive and is not always readily available in all the cases where it is needed. [0005] Publication WO98 / 55405 discloses a method for removing sulphate and calcium from a water stream comprising the steps of: mixing the water stream with a certain a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C02F9/00C02F1/52C02F1/66C01F7/06C02F1/38C02F1/24C02F11/121C02F11/145C02F101/10C02F103/10C01F7/04C01F7/78C02F11/122C02F11/123C02F11/14
CPCC02F1/24C02F1/38C02F1/5236C02F1/5245C02F1/66C02F9/00C02F11/122C02F11/123C02F11/14C02F2001/007C02F2101/101C02F2103/10C02F2209/02C02F2209/06C02F2209/44C02F2301/046C02F2301/08C01F7/04C01F11/18C01F11/46C01F7/78C02F1/58
Inventor M·马蒂凯宁
Owner METSO OUTOTEC (FINLAND) OY
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