CN1524841A - Method for reclaiming calcium oxalate from sewage comprising oxalic acid - Google Patents
Method for reclaiming calcium oxalate from sewage comprising oxalic acid Download PDFInfo
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- CN1524841A CN1524841A CNA031248454A CN03124845A CN1524841A CN 1524841 A CN1524841 A CN 1524841A CN A031248454 A CNA031248454 A CN A031248454A CN 03124845 A CN03124845 A CN 03124845A CN 1524841 A CN1524841 A CN 1524841A
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- Prior art keywords
- waste water
- oxalic acid
- calcium sulfate
- neutralization
- oxalate
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Abstract
The invention relates to a process for reclaiming valuable substance from waste water, in particular a process for reclaiming calcium oxalate from waste water containing oxalic acid, characterized in that the process comprises the two steps of lime cream neutralization and calcium sulfate substitution, wherein the step of lime cream neutralization comprises charging lime cream into waste water containing oxalic acid for neutralization reaction, controlling the reaction temperature to be 80-90 deg. C, when the content of oxalic acid roots in the waste water amounts to 22-25 g/L, ceasing the charging of lime cream, while the calcium sulfate substitution step comprises charging calcium sulfate cream exceeding stoichiometric calculation amount into the waste water to be processed for displacement reaction, controlling the reaction temperature to be 95-98 deg. C, thus obtaining calcium oxalate and acid wastewater.
Description
Technical Field
The invention relates to a method for recovering valuable substances from waste water, in particular to a method for recovering calcium oxalate from waste water containing oxalic acid.
Background
In the process of producing borneol by using oxalic acid as a catalyst, the recovery work of oxalic acid always troubles various production enterprises, and various manufacturers always use lead sulfate (P) for many yearsbSO4) The biggest disadvantage of this method for the recovery of oxalic acid from the intermediate is that lead inevitably enters the waste water, causing serious environmental pollution, and at the same time, the activity of lead sulfate gradually decreases with the passage of time, resulting in low yieldThe production cost is too high.
Disclosure of Invention
The invention aims to provide a method for recovering calcium oxalate from oxalic acid-containing wastewater generated in the production process of borneol by a two-stage process of lime milk neutralization-calcium sulfate milk replacement, so as to overcome the defects of environmental pollution caused by lead and the like in the traditional lead sulfate method.
The technical scheme of the invention is to treat oxalic acid-containing wastewater generated in the production process of borneol by two steps of lime milk neutralization and calcium sulfate milk replacement so as to achieve the dual purposes of recycling calcium oxalate and not causing lead pollution to the environment.
The method is characterized by comprising two steps of lime milk neutralization and calcium sulfate replacement, wherein the lime milk neutralization step is to add lime milk into waste water containing oxalic acid for neutralization reaction, control the reaction temperature to be 80-90 ℃, and stop adding lime milk when the oxalic acid radical content in the waste water is 22-25g/L, so as to obtain part of calcium oxalate and waste water to be treated; and the calcium sulfate replacement step is to add calcium sulfate milk with the stoichiometric excess according to the content of oxalate in the wastewater to be treated, perform replacement reaction, and control the reaction temperature to be 95-98 ℃ to obtain calcium oxalate and acidic wastewater.
The dosage of the calcium sulfate milk exceeds the weight multiple of the stoichiometric quantity by more than 2 times.
The invention has the advantages that: by the two-stage process of lime milk neutralization and calcium sulfate milk replacement, oxalic acid in waste water generated in the production process of borneol is recovered, the pollution of lead ions to the environment by the traditional lead sulfate method is avoided, and meanwhile, the calcium sulfate has stable chemical property and low price, so that the recovery rate of the oxalic acid is improved, and the production cost is greatly reduced.
Drawings
The attached figure is a process flow diagram of the invention.
Detailed Description
The present invention and its embodiments are described in further detail below with reference to the accompanying drawings.
Example 1
Firstly, putting 5.1 cubic meters of waste water containing 209g/L of oxalic acid into an enamel reaction kettle with a jacket, starting stirring, adding lime milk, performing neutralization reaction, controlling the reaction temperature to be 80 ℃, stopping adding the lime milk until the oxalic acid radical content in the waste water is 22g/L, and obtaining partial calcium oxalate and the waste water to be treated, wherein the main neutralization reaction is as follows:
adding 346.8kg of calcium sulfate (in terms of CaSO) according to the content of oxalate in the wastewater to be treated being 22g/L42 times of stoichiometric amount) of the emulsion, controlling the reaction temperature to be 95 ℃, obtaining calcium oxalate and acidic wastewater, wherein the main replacement reaction comprises the following steps:
the reacted materials are dried by a centrifuge, and are washed twice by water, and the dried calcium oxalate can reach the following indexes by analysis:
chemical composition content (%)
CaC2O4(dry basis) is more than or equal to 88
CaSO4(dry product) is less than or equal to 10
Na+≤0.2
Fe2+≤0.2
And sending the qualified product to produce oxalic acid and calcium sulfate.
Example 2
Adding lime milk into 4.8 cubic meters of waste water containing oxalic acid for neutralization reaction, controlling the reaction temperature at 85 ℃ until the oxalic acid radical content in the waste water is 25g/L, and then adding 371kg of calcium sulfate (CaSO)42 times stoichiometric amount on a dry basis), the temperature of the metathesis reaction was controlled at 95 ℃ and the remainder was the same as in example 1.
Example 3
Controlling the neutralization reaction temperature to be 90 ℃, and adding 400kg of calcium sulfate (according to CaSO) in the replacement reaction4Dry amount 2 times more than stoichiometric amount), the temperature of the metathesis reaction was controlled to 98 ℃, and the rest was the same as in example 1.
Claims (2)
1. A method for recovering calcium oxalate from waste water containing oxalic acid is characterized by comprising two steps of lime milk neutralization and calcium sulfate replacement, wherein the lime milk neutralization step is to add lime milk into the waste water containing oxalic acid for neutralization reaction, control the reaction temperature to be 80-90 ℃, and stop adding the lime milk when the oxalate content in the waste water is 22-25g/L, so as to obtain part of calcium oxalate and waste water to be treated; and the calcium sulfate replacement step is to add calcium sulfate milk with the stoichiometric excess according to the content of oxalate in the wastewater to be treated, perform replacement reaction, and control the reaction temperature to be 95-98 ℃ to obtain calcium oxalate and acidic wastewater.
2. The method of claim 1, wherein the calcium sulfate milk is used in an amount that is more than 2 times the stoichiometric amount by weight.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 03124845 CN1224600C (en) | 2003-09-18 | 2003-09-18 | Method for reclaiming calcium oxalate from sewage comprising oxalic acid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 03124845 CN1224600C (en) | 2003-09-18 | 2003-09-18 | Method for reclaiming calcium oxalate from sewage comprising oxalic acid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1524841A true CN1524841A (en) | 2004-09-01 |
| CN1224600C CN1224600C (en) | 2005-10-26 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 03124845 Expired - Fee Related CN1224600C (en) | 2003-09-18 | 2003-09-18 | Method for reclaiming calcium oxalate from sewage comprising oxalic acid |
Country Status (1)
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| CN (1) | CN1224600C (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101012165B (en) * | 2007-02-09 | 2012-07-18 | 太原理工大学 | Process of preparing oxalic acid by calcium sulfate cycle method |
| CN103642852A (en) * | 2013-11-29 | 2014-03-19 | 大连创达技术交易市场有限公司 | Preparation method of oxalate |
| CN104086406A (en) * | 2014-07-15 | 2014-10-08 | 中南大学 | Method for separating and recycling sodium oxalate from waste water containing oxalic acid |
| TWI583667B (en) * | 2016-04-29 | 2017-05-21 | 嘉藥學校財團法人嘉南藥理大學 | A method of synthesizing homogeneous granular oxalate crystals by using fluidized-bed crystallization technology |
| CN113929226A (en) * | 2021-10-29 | 2022-01-14 | 西安泰金工业电化学技术有限公司 | Oxalic acid waste liquid recovery system and recovery method |
-
2003
- 2003-09-18 CN CN 03124845 patent/CN1224600C/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101012165B (en) * | 2007-02-09 | 2012-07-18 | 太原理工大学 | Process of preparing oxalic acid by calcium sulfate cycle method |
| CN103642852A (en) * | 2013-11-29 | 2014-03-19 | 大连创达技术交易市场有限公司 | Preparation method of oxalate |
| CN104086406A (en) * | 2014-07-15 | 2014-10-08 | 中南大学 | Method for separating and recycling sodium oxalate from waste water containing oxalic acid |
| TWI583667B (en) * | 2016-04-29 | 2017-05-21 | 嘉藥學校財團法人嘉南藥理大學 | A method of synthesizing homogeneous granular oxalate crystals by using fluidized-bed crystallization technology |
| CN113929226A (en) * | 2021-10-29 | 2022-01-14 | 西安泰金工业电化学技术有限公司 | Oxalic acid waste liquid recovery system and recovery method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1224600C (en) | 2005-10-26 |
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