CN1330047A - Process for treating sewage by neutralization and ion salt oxidization - Google Patents
Process for treating sewage by neutralization and ion salt oxidization Download PDFInfo
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- CN1330047A CN1330047A CN 00113056 CN00113056A CN1330047A CN 1330047 A CN1330047 A CN 1330047A CN 00113056 CN00113056 CN 00113056 CN 00113056 A CN00113056 A CN 00113056A CN 1330047 A CN1330047 A CN 1330047A
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Abstract
A process for treating sewage by neutralization and iron salt oxidization is disclosed. In neutralization step, most of the As ions in sewage are removed. In iron salt oxidization step, copper ions are added to promote the oxidization of Fe and As ions to generate iron arsenate and iron hydroxide for further removal of As ions by deposition. Its advantages are simple equipment, high effect and low cost.
Description
The invention relates to a method for treating acidic sewage discharged in the non-ferrous metal smelting industry and the chemical industry.
In the smelting process and chemical production of nonferrous metals, a large amount of industrial sewage water can be generated, the sewage water contains harmful substances such as copper, arsenic, lead, zinc, cadmium, fluorine and the like, can not be directly discharged, and can be discharged outwards only after being purified and meeting the national discharge standard so as to meet the requirement of environmental protection. In the treatment of these effluents, the most difficult one to remove is arsenic. At present, the sewage treatment methods adopted by enterprises in China mainly comprise the following methods: (1) the method is characterized in that ferric salt (ferrous salt) and lime are added into sewage at the same time, arsenic is removed through neutralization and precipitation, if the neutralization and precipitation do not reach the standard, the sewage can be repeatedly treated for several times, but the consumption of ferric salt is too large, the amount of neutralized slag is large, if the sewage is repeatedly treated for several times, the water treatment cost is too high, enterprises are difficult to bear, and the sewage can only treat low-arsenic low-acid sewage, namely sewage water containing arsenic less than 1g/l, the pH value of the sewage treated by the method is about 10-11, most of the enterprises use acid liquor to reversely adjust the sewage water to the pH value of about 7 and then discharge the sewage water, the industrial wastewater discharged does not reach the national industrial discharge standard, certain pollution is caused to the environment, and the content of element arsenic mainly exceeds the standard. (2) The sulfuration coprecipitation-neutralization method is characterized by firstly adding sodium sulfide into waste acid water to remove a large amount of arsenic, then carrying out neutralization precipitation to ensure that the treated wastewater reaches the standard and is discharged, and is usually used for treating high-arsenic high-acid sewage, namely waste acid water containing 1-20g/l of arsenic, but the flow is long, the equipment is complex, the processing cost is extremely high, and common enterprises cannot bear the method. Both of the above methods have a serious problem of secondary pollution of slag.
Theinvention aims to solve the problems in the prior art and provide a sewage treatment method which can effectively remove arsenic in high-arsenic high-acid or low-arsenic low-acid sewage, has simple equipment, low cost, small slag amount and small secondary pollution or even no pollution, so that the discharged wastewater reaches the secondary standard in the national comprehensive sewage discharge standard (GB 8978-1996).
The purpose of the invention is realized by the following technical scheme.
The processing method comprises the following steps: (1) adding carbide slag or lime into sewage, removing most of arsenic in the sewage by a neutralization precipitation method, mainly adjusting the acidity of a neutralization solution subjected to neutralization precipitation treatment to a pH value of more than or equal to 11, and reducing the content of arsenic to below 50 mg/l; (2) precipitating and separating the neutralization solution and the neutralization residue, and reducing the suspended matters in the neutralization solution to below 50 mg/l; (3) adding iron salt into the supernatant liquid with the separated neutralized slag, and blowing air for oxidation to lead Fe2+Is oxidized into Fe3+，As+3By oxidation to As+5The property of arsenic and iron to generate stable ferric arsenate compound and the property of ferric hydroxide and ferric arsenate co-precipitatingFurther removing arsenic; (4) adding copper ions into the waste acid water which does not contain copper ions in the waste acid water in any working procedure before the ferric salt is oxidized; the ferric salt is ferrous sulfate or ferric sulfate or polyferric; the addition amount of copper ions is more than 0.1mg/l
The neutralization precipitation is to utilize heavy metal ions and OH-The ion reaction generates hydroxide precipitate which is difficult to dissolve in water, so that the wastewateris purified, and the reaction formula is as follows:
Reaction type solubility product: kso＝[Me2+][OH--]2
Expressed logarithmically: lg [ Me]2+]＝LgKso－2LgKw－2PH
In the formula, LgKso、LgKw(the ionic product of water) is a constant, expressed in K, then: lg [ Me]2+]＝K－2PH
From the above formula, it is seen that the concentration of the residual heavy metal ions in the wastewater is determined by the pH value during the neutralization and precipitation, and within a certain range, the higher the pH value of the wastewater is, the lower the concentration of the residual heavy metal ions is. When a single metal exists in water, the content of the metal is reduced to the industrial discharge standard, and the required pH value is controlled to be about 10. However, in the production process, various ions in the wastewater coexist and interfere with each other to a certain extent, which is beneficial to generating the co-precipitation effect, but part of amphoteric metals, such as Zn and Pb, can generate the redissolution phenomenon of hydroxide precipitates under the high pH value, and the precipitation effect is reduced.
When arsenic in wastewater is neutralized, calcium arsenite and calcium fluoride precipitate are generated and removed, and the reaction formula is as follows:
solubility product: kso＝[AsO3- 3]2[Ca2+]3
Expressed logarithmically: lg [ AsO]3- 3]＝(LgKso－3Lg[Ca2+])/2
As shown by the above formula, residual AsO in the wastewater3- 3At a concentration of Ca2+Determination of concentration of Ca in the wastewater2+Higher concentration, residual AsO3- 3The lower the ions. When the ratio of calcium to arsenic is Ca: when As is 3 or more, the pH value is in the range of 12 to 13.5, and the concentration of arsenic remaining in the solution is remarkably reduced to 50mg/l or less.
In conclusion, during the neutralization and precipitation, heavy metal, arsenic and fluorine can be generated and precipitated to be removed, the heavy metal and the fluorine are easy to remove and reach the standard, the arsenic is difficult to remove, and the pH value and Ca of the neutralization solution are increased to remove the arsenic to the maximum extent2+And (4) concentration.
The iron salt is used for removing arsenic by utilizing the property that arsenic and iron generate stable ferric arsenate compounds and ferric hydroxide and ferric arsenate are jointly precipitated.
The iron salt selected by us is ferrous sulfate, and the dearsenification of the ferrous sulfate is divided into two steps: oxidation and precipitation. In the oxidation stage, Fe2+And AsO3- 3Is oxidized into Fe3+And AsO3- 4The necessary condition for realizing the oxidation process is that a certain amount of copper ions are required to be used as a catalyst in the treated liquid, so for enterprises which do not contain copper ions in the polluted acid water, a certain amount of copper ions, often CuSO, are added into the treated liquid before the ferric salt is oxidized4. In alkaline solution, the oxidation stage simultaneously produces a precipitation reaction, the reaction formula is as follows:
ΔG°298＝-393.55KJ
△G°298＝-342.86KJ
ΔG°298＝-257.02KJ
ΔG°298＝-50.69KJ
by the above reaction,. DELTA.G °298It is shown that ferric arsenate is more stable than calcium arsenate and ferric hydroxide [25 ℃, PH 3-8, solubility of the above compounds: ca3(AsO4)2(0.13g/l)＞Fe(OH)3(6.44×10-7g/l)＞FeAsO4(1.46×10-8g/l)]Therefore, the iron salt has good arsenic removal effect.
In addition to ferric arsenate generated from iron and arsenic, ferric hydroxide can be used as a carrier to be precipitated together with arsenate ions and ferric arsenate, and the reaction formula is as follows:
FeAsO4is stable, but the pH value is controlled to be 6-9, which can cause the redissolution reaction when the pH value is more than 10. The redissolution reaction formula is as follows:
when ferric salt is oxidized, the pH value of the solution can be reduced to 3-4 due to a certain amount of acid discharged, and at the moment, the pH value can be adjusted to 6-9 only by adding carbide slag into the solution so as to reach the national discharge standard.
FIG. 1 is a process flow diagram of the present invention.
The process flow is characterized in that: (1) the waste acid purification process is divided into two sections: first-stage neutralization and precipitation, and second-stage ferrous sulfate oxidation to further remove arsenic; (2) and the pH value of neutralization is increased to be more than or equal to 11.0, so that heavy metal and fluorine precipitation reach the standard. Removing more than 98% of arsenic to reduce the arsenic content of the neutralization solution to below 50 mg/l; (3) the neutralization solution is separated from the neutralized slag by precipitation, and the suspended substance in the neutralization solution is reduced to below 50 mg/l; (4) adding FeSO into the neutralization solution4.7H2And O, blowing and oxidizing to reduce the residual arsenic content to below 0.5 mg/l.
The production process comprises the following steps: the waste acid discharged from the factory flows into the regulating tank through the pipeline and is regulatedThe waste acid is conveyed to a neutralizing tank by a pump, and carbide slag and CuSO are added4Continuously neutralizing, stirring by compressed air, conveying the neutralized liquid to a vertical flow settling tank by a pump through an intermediate tank for settling, and adding a precipitator polyacrylamide (3# agent) in the intermediate tank. The vertical flow underflow is discharged intermittently and is conveyed to a concentration tank by a pump for concentration, the underflow of the concentration tank is dewatered by a pump vacuum disc filter, filter cakes (namely sludge) return to batching, the supernatant and the filtrate of the concentration tank automatically flow into a mixing tank, and are conveyed back to a vertical flow settling tank intermittently by the pump. The vertical flow supernatant fluid automatically flows into an oxidation tank, ferrous sulfate is added for continuous oxidation dearsenification, the PH value is adjusted by carbide slag slurry, and compressed air is used for oxidation. The oxidizing liquid flows into the radial flow sedimentation tank from the self to be settled, and the radial flow supernatant flows into the interception pump station and is discharged into the river through the discharge pump. The precipitator polyacrylamide (3# agent) is added into a chute between an oxidation tank and a radial flow sedimentation tank. The radial flow bottom flow is continuously conveyed to a concentration tank for concentration by a pump, the bottom flow is pumped into a vacuum disc filter for dehydration, and a filter cake returns to batching. The filtrate automatically flows into the mixing tank, and the supernatant of the concentration tank automatically flows back into the auxiliary flow sedimentation tank.
The technical and economic indexes in the production process are as follows:
(1) and a neutralization process:
the reaction time is0.5-1.0h, the operation temperature is normal temperature
pH value of 11.0-12.5, effluent acid treatment capacity of 30-40m3/h
(2) And settling the neutralized slag:
the dosage concentration of the 3# agent is 1 percent 02-31/m3Solutions of
Throughput of treatment 1.0-1.2m3/m3The flow rate of the h bottom is 15 to 20 percent
(3) And an oxidation process:
the iron-arsenic ratio is 10-20, the pH value is 6-9
The oxidation time is 2-3h, the operation temperature is normal temperature
(4) Iron and arsenic slag sedimentation
The dosage concentration of the 3# agent is 1 percent 01-21/m3Solutions of
The treatment amount is 1.0-1.2m3/m3The flow rate of the h bottom is 15 to 20 percent
(5) Neutralizing the bottoms stream for concentration
The treatment capacity is less than 15m3The underflow amount is less than 50 percent
(6) Iron-arsenic slag underflow concentration
The treatment capacity is less than 15m3The underflow amount is less than 50 percent
(7) Vacuum filtering of neutralized slag
The filtration capacity is 8-12m3450/h vacuum degree of 550mmHg
(8) Iron-arsenic slag vacuum filtration
The filtration capacity is 6-8 m3450/h vacuum degree of 550mmHg
Material consumption:
carbide slag: 16.13Kg/m3Polluted acid CuSO40.1mg/l of contaminated acid
FeSO4.7H2O：2.39Kg/m3Contaminated acid # 3 agent: 4.02g/m3Waste acid
After several years of industrial production, the statistical data of water quality before and after the treatment of the waste acid water and the emission standard are listed in the following table:
average water quality unit before and after sewage treatment: mg/l
| Pollution Name (R) | H2SO4 | Cu | As | Pb | Zn | Cd | F |
| Before treatment Waste water | 4000-- 140000 | 40--280 | 200-- 11500 | 2.6--230 | 60--2100 | 8.0--260 | 30— 30000 |
| After treatment Discharging water | PH6.5--8.5 | 0.27 | 0.25 | 0 35 | 0.44 | 0.045 | 10.0 |
| GB8978 —1996 | PH6--9 | ≤1.0 | ≤0.5 | ≤1.0 | ≤5.0 | ≤0.1 | ≤10 |
As can be seen from the above table, the treatment method of neutralizing iron salt is effective for the treatment of waste acid, and the quality of the treated effluent water reaches the secondary standard in the national Integrated wastewater discharge Standard. The produced neutralization slag and the produced oxidation slag are researched, and the obtained oxidation slag has no secondary pollution problem and weak secondary pollution. Experiments prove that the method for treating the waste acid water has the advantages of feasible technology, reasonable process, simple operation and obvious treatment effect, the removal rate of Cu, As, Zn and Cd is more than 99.9 percent, the removal rate of Pb is more than 98.0 percent, the removal rate of F is more than 97.0 percent, the standard-reaching rate of drainage is 100 percent, and the removal rate of Cu, As, Pb, Zn, Cd and F is more than 80 percent. The cost for treating 1 ton of waste acid is 9.34-12.23 yuan, and compared with other treatment processes, the method is economical.
Claims (3)
1. A neutralization-ferric salt oxidation sewage treatment method is characterized in that sewage is treated by a neutralization process and a ferric salt oxidation process in two stages, and the treatment steps are as follows:
(1) adding carbide slag or lime into sewage, removing most of arsenic in the sewage by a neutralization precipitation method, mainly adjusting the acidity of a neutralization solution subjected to neutralization precipitation treatment to a pH value of more than or equal to 11, and reducing the content of arsenic to below 50 mg/l;
(2) precipitating and separating the neutralization solution and the neutralization residue, and reducing the suspended matters in the neutralization solution to below 50 mg/l;
(3) adding iron salt into the supernatant liquid with the separated neutralized slag, and blowing air for oxidation to lead Fe2+Is oxidized into Fe3+，As+3By oxidation to As+5Further removing arsenic by using the property that arsenic and iron generate stable ferric arsenate compounds and ferric hydroxide and ferric arsenate are jointly precipitated;
(4) and adding copper ions to the waste acid water which does not contain copper ions in the waste acid water in any step before the ferric salt is oxidized.
2. The process of claim 1, wherein the iron salt is ferrous sulfate or ferric sulfate or polymeric iron.
3. The process according to claim 1, wherein the amount of copper ions added is greater than 0.1 mg/l.
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| CNB001130560A CN1142110C (en) | 2000-06-20 | 2000-06-20 | Process for treating sewage by neutralization and ion salt oxidization |
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| CN1142110C CN1142110C (en) | 2004-03-17 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101830583A (en) * | 2010-03-25 | 2010-09-15 | 云南铜业股份有限公司 | Method for treating waste acid by gypsum sedimentation, arsenic oxidizing sedimentation and iron salt neutralization and co-precipitation |
| CN101857325A (en) * | 2010-06-28 | 2010-10-13 | 湘潭大学 | Method for treating iron-containing acidic wastewater |
| CN102502937A (en) * | 2011-11-10 | 2012-06-20 | 山东国大黄金股份有限公司 | Method for purifying arsenic-containing wastewater by using sewage treatment slag |
| CN102502988A (en) * | 2011-10-31 | 2012-06-20 | 锡矿山闪星锑业有限责任公司 | Treatment method of waste water containing arsenic and cadmium in indium production |
| CN104787932A (en) * | 2015-04-29 | 2015-07-22 | 铜陵化学工业集团有限公司 | Treatment method of industrial arsenic wastewater |
| CN104829014A (en) * | 2015-06-03 | 2015-08-12 | 南宁市桂润环境工程有限公司 | Short-distance membrane separation treatment process for lead-zinc industrial beneficiation and smelting wastewater |
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| CN106746028A (en) * | 2017-02-20 | 2017-05-31 | 云南锡业股份有限公司铜业分公司 | A kind of metallurgical waste acid sewage water treatment method |
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| CN107010751A (en) * | 2017-04-01 | 2017-08-04 | 北京中科康仑环境科技研究院有限公司 | A kind of integrated conduct method of high concentration arsenic-containing acid waste water |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101830583A (en) * | 2010-03-25 | 2010-09-15 | 云南铜业股份有限公司 | Method for treating waste acid by gypsum sedimentation, arsenic oxidizing sedimentation and iron salt neutralization and co-precipitation |
| CN101830583B (en) * | 2010-03-25 | 2012-12-12 | 云南铜业股份有限公司 | Method for treating waste acid by gypsum sedimentation, arsenic oxidizing sedimentation and iron salt neutralization and co-precipitation |
| CN101857325A (en) * | 2010-06-28 | 2010-10-13 | 湘潭大学 | Method for treating iron-containing acidic wastewater |
| CN101857325B (en) * | 2010-06-28 | 2011-12-28 | 湘潭大学 | Method for treating iron-containing acidic wastewater |
| CN102502988A (en) * | 2011-10-31 | 2012-06-20 | 锡矿山闪星锑业有限责任公司 | Treatment method of waste water containing arsenic and cadmium in indium production |
| CN102502937A (en) * | 2011-11-10 | 2012-06-20 | 山东国大黄金股份有限公司 | Method for purifying arsenic-containing wastewater by using sewage treatment slag |
| CN102502937B (en) * | 2011-11-10 | 2013-06-19 | 山东国大黄金股份有限公司 | Method for purifying arsenic-containing wastewater by using sewage treatment slag |
| CN105765090A (en) * | 2013-11-29 | 2016-07-13 | 奥图泰(芬兰)公司 | Method and arrangement of separating arsenic from starting materials |
| CN104787932A (en) * | 2015-04-29 | 2015-07-22 | 铜陵化学工业集团有限公司 | Treatment method of industrial arsenic wastewater |
| CN104876362A (en) * | 2015-05-19 | 2015-09-02 | 武汉飞博乐环保工程有限公司 | Acid purification recycling system |
| CN104876362B (en) * | 2015-05-19 | 2017-02-01 | 武汉飞博乐环保工程有限公司 | Acid purification recycling system |
| CN104829014A (en) * | 2015-06-03 | 2015-08-12 | 南宁市桂润环境工程有限公司 | Short-distance membrane separation treatment process for lead-zinc industrial beneficiation and smelting wastewater |
| CN106746028A (en) * | 2017-02-20 | 2017-05-31 | 云南锡业股份有限公司铜业分公司 | A kind of metallurgical waste acid sewage water treatment method |
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| CN109078962A (en) * | 2018-08-30 | 2018-12-25 | 西北矿冶研究院 | Combined treatment method of arsenic-containing acidic wastewater, red mud and carbide slag |
| CN109078962B (en) * | 2018-08-30 | 2021-06-18 | 西北矿冶研究院 | Combined treatment method of arsenic-containing acidic wastewater, red mud and carbide slag |
| CN110255770A (en) * | 2019-07-03 | 2019-09-20 | 昆明理工大学 | A kind of method that Jarosite Residues cooperate with arsenic in calcium carbide Slag treatment nonferrous smelting waste acid |
| CN110255770B (en) * | 2019-07-03 | 2022-05-27 | 昆明理工大学 | Method for treating arsenic in nonferrous smelting waste acid by using jarosite slag and carbide slag |
| CN110745930A (en) * | 2019-09-23 | 2020-02-04 | 昆明理工大学 | Magnetic Fe3O4Method for treating arsenic in nonferrous smelting waste acid by cooperating with calcium oxide |
| CN112317513A (en) * | 2020-10-26 | 2021-02-05 | 湖南有色金属研究院 | Method for stabilizing arsenic-containing waste residue |
| CN112777789A (en) * | 2020-12-23 | 2021-05-11 | 云南宇菲工程设计有限责任公司 | Waste acid treatment method |
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