CN1116611A - Treatment of waste galvanized water with its treating agent and method for recovery of precipitate - Google Patents
Treatment of waste galvanized water with its treating agent and method for recovery of precipitate Download PDFInfo
- Publication number
- CN1116611A CN1116611A CN 94112437 CN94112437A CN1116611A CN 1116611 A CN1116611 A CN 1116611A CN 94112437 CN94112437 CN 94112437 CN 94112437 A CN94112437 A CN 94112437A CN 1116611 A CN1116611 A CN 1116611A
- Authority
- CN
- China
- Prior art keywords
- value
- precipitate
- wastewater
- zinc
- filtering
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Removal Of Specific Substances (AREA)
Abstract
The treating agent for waste zinc-plating liquid contains such components as caustic alkali (25-27%), urea (2-4%), hexamethylene tetramine (1-2%), phosphoric acid or its salt (2-6%), bone glue (1-3%) and water (the balance). Using said treating agent can produce zinc oxide through adding it to said waste liquid, mixing and controlling its pH value being 8.2-9.0, standing, separation, addition of hydrochloric acid and sodium hydroxide to regulate its pH value being 4,6 and 7 while filtering out precipitates, obtaining the precipitate when pH value is equal to 8, and drying at 200-250 deg.C.
Description
The invention relates to a method for treating wastewater.
At present, the chemical method is widely applied to the treatment of electroplating wastewater at home and abroad, because the chemical method can adopt different treating agents to treat the electroplating wastewater according to different treatment objects such as chromium, copper, nickel and cyanogen. This treatment facilitates their recycling. Meanwhile, the chemical treatment method needs less equipment, has less one-time investment and is simple and easy to operate. However, no special treating agent is used for treating the zinc electroplating wastewater at present due to the special property of zinc.
In view of the defects in the prior art, the invention aims to provide a recovery method for specially treating galvanizing waste water and precipitates.
The object of the invention can be achieved by the following measures: a zinc-plating wastewater treatment agent is characterized in that: the composition comprises the following components in percentage by weight: 25-27% of caustic alkali, 2-4% of urea, 1-2% of hexamethylenetetramine, 2-6% of phosphoric acid or salt, 1-3% of bone glue and the balance of water. The method for treating the galvanizing wastewater by adopting the galvanizing wastewater treating agent comprises the following steps: a, checking the concentration of zinc ions in the zinc-plating wastewater, adjusting the concentration of the zinc ions not to exceed 1000mg/l, b, adjusting the pH value of the wastewater to be between 3 and 5 by using sulfuric acid, c, adjusting the pH value of the wastewater to be between 7.0 and 7.2 by using 15 to 25 percent sodium hydroxide, d, adding 1.0 to 1.5 liters of treating agent into each ton of wastewater, stirring for 5 to 7 minutes, controlling the pH value to be between 8.2 and 9.0 by using 15 to 25 percent sodium hydroxide solution, standing for 4 to 16 hours, and filtering and separating to obtain a separation solution and a solid precipitate. The recovery method of the precipitate after the galvanized wastewater is treated by the galvanized wastewater treatment agent comprises the following steps; a, adding industrial hydrochloric acid into the precipitate to dissolve the precipitate, filtering to remove insoluble substances, b, adjusting the pH value of a zinc-containing solution by using a sodium hydroxide solution, filtering to remove the insoluble substances when the pH value is 4, filtering to remove the insoluble substances when the pH value is 6, filtering to remove the insoluble substances when the pH value is 7, filtering to collect the precipitate when the pH value is 8.5, c, washing the precipitate by using deionized water or distilled water, and dehydrating and drying for 1-2 hours at the temperature of 200-250 ℃. The concentration of sodium hydroxide for adjusting the pH value is 15-25%.
The method mainly comprises the steps of treating the galvanizing waste water by using a chemical treatment agent, wherein the liquid obtained by separation is standard water, and the precipitate is extracted to obtain zinc oxide which can be recycled.
The method of the invention firstly carries out chemical treatment on the galvanizing waste water. The main precipitator of the zinc-plating wastewater treatment agent is caustic alkali such as potassium hydroxide or sodium hydroxide, and the caustic alkali and the zinc ions can generate composite precipitate in the presence of sulfate radicals, and the reaction equation is as follows:
the proportion of sodium hydroxide or potassium hydroxide in caustic alkali in the zinc plating wastewater treatment agent is 25-27%. If their proportion is less than 25%, the divalent zinc precipitates incompletely and remains in the discharge water, with the possibility of contamination. But their proportion is higher than 27% because zinc hydroxide has amphiphilicity and begins to dissolve to become soluble ZnO when PH is more than 13.52Thus separating ZnO from the liquid2The content will increase and still not meet the specified treatment standard. At the position ofThe treating agent also comprises a coagulant urea for accelerating coagulation of the small-particle precipitates,it is used in combination with hydroxide radical in strong alkali to form homogeneous precipitate, and has low proportion in treating agent, no obvious effect and high content. Therefore, the proportion thereof in the treating agent is preferably 2 to 4%. The treating agent also comprises another auxiliary precipitator hexamethylenetetramine with coagulation function, and the proportion of the hexamethylenetetramine in the treating agent is 1-2%. The treating agent also contains surfactant for accelerating precipitate formation, which can be phosphoric acid, and its soluble salt such as potassium phosphate or sodium phosphate, and their proportion in the treating agent is preferably 2-6%. Animal glue, namely bone glue, is also added into the treating agent, and is a coprecipitator which can be used for precipitating a trace amount of Zn in the wastewater, so that the aim of more thoroughly removing zinc ions in the wastewater is fulfilled. When the content of the animal glue is less than 1%, the effect is not obvious, but when the content of the animal glue is more than 3%, the zinc removal effect is obvious, but the animal glue is colloidal, so that filter cloth holes are easy to block during filtering, and the filtering is difficult, therefore, the proportion of the animal glue in the treating agent is 1-3%. The rest proportion of the treating agent is water.
The preparation method of the galvanized wastewater treatment agent comprises the following steps: taking about half weight of water of the treating agent to be prepared and placing the water into a container, adding caustic alkali, urea, hexamethylenetetramine, phosphoric acid or its soluble salt according to the amount of the proportion relation in turn, adding the next material after the former material is stirred and dissolved, then taking bone glue according to the proportion relation, dissolving the bone glue in hot water with the weight about 5 times of that of the bone glue, preferably, the water temperature is 80-90 ℃, adding the bone glue into the mixture of the materials after the bone glue is completely dissolved, finally adding the rest amount of water, and uniformly stirring to obtain the treating agent.
The treatment method of the galvanizing wastewater comprises the following steps: a, if the concentration of the galvanized wastewater exceeds 1000mg/l, the concentration of zinc ions in the treated wastewater needs to be adjusted within 1000mg/l, otherwise, the sedimentation speed is too slow due to too high concentration.b, adjusting the pH value of the wastewater to be between 3 and 5 by using sulfuric acid. The treating agent of the zinc-plating wastewater is cationThe treating agent, therefore, the wastewater must be made acidic to ZnO2All become Zn2+. In addition, because sulfate radicals participate in the composite precipitation, when the dosage of the sulfuric acid is insufficient, a part of zinc ions still exist in the solution due to insufficient sulfate radicals, so that the separated water exceeds the standard. If the amount of the sulfuric acid used is too large, the amount of the sulfate radical remaining in the filtrate increases, which is disadvantageous for filtrate recovery. c, adjusting the pH value of the wastewater to 7.0-7.2 by using 15-25% sodium hydroxide to reduce the consumption of caustic alkali in the treating agent and ensure the treatment effect of the treating agent. d, adding the treating agent, adding 1.0-1.5 liters of the treating agent into each ton of the galvanized wastewater, fully stirring for 5-7 minutes, and controlling the pH value to be 8.2-9.0 by using 15-25% sodium hydroxide solution to ensure that the zinc-plated wastewater is completely precipitated. e, standing for 4-16 hours, and then filtering and separating to obtain a separation liquid and a solid precipitate.
Treatment of the separated liquid: the supernatant and the filtrate obtained by the treatment of the galvanizing wastewater treatment agent are collectively called separation liquid, can reach the specified standard, and can be sent back to an electroplating workshop to be used as rinsing water continuously. However, trace sodium ions and chloride ions still exist in the separation liquid, and when the separation liquid is recycled for a certain number of times, the content of the sodium ions and the chloride ions reaches a certain concentration, workpieces are corroded, and therefore the separation liquid needs to be treated by an ion exchange column, clean deionized water can be obtained, and the deionized water can be recycled.
Treatment and recovery of solid precipitate: in addition to a large amount of zinc, a certain amount of calcium, magnesium, iron, chromium, copper, sulfate radical, chloride radical and the like are contained in the solid precipitate obtained by filtration and separation. Dissolving the precipitate with industrial hydrochloric acid, preferably hydrochloric acid/precipitate at a ratio of 2: 1, filtering to remove insoluble substances, and adjusting pH of the zinc-containing solution with sodium hydroxide solution, preferably 15-25% sodium hydroxide. Iron ions form ferric hydroxide precipitate at PH 4, and iron is removed by filtration.The pH was adjusted further with sodium hydroxide solution, chromium precipitated as chromium hydroxide at pH 6 and was removed by filtration. The pH was then adjusted with sodium hydroxide solution, the copper ions precipitated as copper hydroxide at pH 7, and the copper was removed by filtration. Adjusting pH with sodium hydroxide solution, precipitating zinc hydroxide when pH is 8.5, and filtering to remove SO4 2-And CI-The filtrate is obtained by separating the precipitate containing the zinc oxide, washing the precipitate with deionized water or distilled water, and then dehydrating and drying the precipitate at the temperature of 200℃ and 250 ℃ for 1 to 2 hours to obtain the white zinc oxide.
Compared with the prior art, the method of the invention has the following advantages:
1. the treating agent of the invention has high sedimentation speed for treating the zinc-plating waste water, has higher cohesion and is convenient for separation and recovery treatment.
2. The method has simple process, convenient operation and low one-time investment, and only uses 6.5 yuan for treating one ton of galvanizing waste water. The treated discharged water completely reaches the national discharge standard (less than 2mg/l) and can be recycled.
3. The precipitate obtained by separation after treatment by the treating agent is extracted to obtain pure zinc oxide which is used for preparing a zincate plating bath to electroplate workpieces, and the product quality is all qualified. The recovered zinc oxide can also be processed into zinc nitrate, zinc dihydrogen phosphate and zinc phosphate as main raw materials for producing the phosphating solution.
4. The method can recycle the separated solid precipitate and the separated liquid, thereby not only having remarkable economic benefit, but also avoiding secondary pollution and effectively protecting the environment.
Example 1
Adding 25 parts of industrial pure potassium hydroxide into a container previously containing 55 parts of water, and stirring to completely dissolve the potassium hydroxide. Then 4 parts of urea is added into the container and stirred to completely dissolve the urea. Then 1 part of hexamethylenetetramine is added into the container and stirred to completely dissolve the hexamethylenetetramine. 6 parts of potassium phosphate is added into the container and stirred to dissolve thepotassium phosphate completely. Dissolving 1 part of animal glue in 5 parts of hot water at the temperature of 80-90 ℃, adding the animal glue into a container containing the substances after the animal glue is completely dissolved, adding 3 parts of water, and uniformly stirring to obtain 100 parts of the treating agent.
Example 2
27 parts of industrial pure sodium hydroxide was added to a container previously containing 49 parts of water, and stirred to completely dissolve the sodium hydroxide. Then 2 parts of urea is added into the container, and the urea is completely dissolved by stirring. Then 2 parts of hexamethylenetetramine are added into the container and stirred to completely dissolve the hexamethylenetetramine. Then 2 parts of phosphoric acid is added into the container, and the mixture is stirred to completely dissolve the phosphoric acid. Dissolving another 3 parts of animal glue in 15 parts of hot water at the temperature of 80-90 ℃, adding the animal glue into a container containing the above substances after the animal glue is completely dissolved, and uniformly stirring to obtain 100 parts of the treating agent.
Example 3
One ton of zinc-plating waste water was taken out, its zinc ion concentration was examined to be 342mg/l, the PH of the waste water was adjusted to 5 with 1 + 3 sulfuric acid (sulfuric acid: water: 1: 3), 7.2 with 15% sodium hydroxide, 1.0 liter of the treating agent of example 2 was added to the waste water, and the mixture was sufficiently stirred for 5 minutes, and the PH was controlled to 8.2 with 15% sodium hydroxide, and after standing for 4 hours, it was filtered, and the zinc content of the filtrate was 0.3 mg/l. Adding industrial hydrochloric acid into the solid precipitate obtained by separation, wherein the dosage of the industrial hydrochloric acid to the precipitate is 2: 1. The hydrochloric acid dissolvesthe precipitate and removes insoluble matter by filtration, the pH is adjusted with 15% sodium hydroxide, and iron hydroxide is removed by filtration when the pH is 4. The pH was adjusted further with 15% sodium hydroxide and the filtrate was filtered to remove chromium hydroxide at pH 6. Then the PH value is adjusted by 15 percent sodium hydroxide, copper hydroxide is removed by filtration when the PH value is 7, then the PH value is adjusted by 15 percent sodium hydroxide, filter residue precipitate is retained by filtration when the PH value is 8.5, the precipitate is washed by deionized water for three times, and then the precipitate is dehydrated and dried in an oven at the temperature of 200 ℃ and 250 ℃ for 1 to 2 hours, and 436 g of white zinc oxide can be obtained.
Example 4
One ton of zinc plating waste water is taken out, the concentration of zinc ions is checked to be 600mg/l, and the PH value of the waste water is adjusted by 1 + 3 sulfuric acid to be 3. The pH of the waste water was adjusted to 7.0 with 25% sodium hydroxide, 1.5 liters of the treating agent of example 1 was added to the waste water, and the mixture was sufficiently stirred for 7 minutes, the pH was adjusted to 9 with 25% sodium hydroxide, and the mixture was left standing for 16 hours and then filtered, whereby the zinc content in the filtrate was 0.8 mg/l. Since the zinc plating waste water was recycled three times, it was sent to an ion exchange column for treatment. Cation exchange resin 732 and anion exchange resin 710 are respectively used in the exchange column. Sodium and chloride ions were not detectable in the effluent from the column. To the solid precipitate obtained by the separation, industrial hydrochloric acid was added in a ratio of 2: 1 (hydrochloric acid: precipitate) to dissolve the precipitate, and insoluble matter was removed by filtration, and the PH was adjusted with 25% sodium hydroxide, and the procedure of example 3 was repeated to obtain 766 g of white zinc oxide.
TABLE 1 comparison table of zinc ion content before and after treatment of zinc-plating wastewater
Note: the supernatant/filtrate is shown. TABLE 2 test conditions of various indexes of workpieces electroplated with recycled zinc oxide
Note: all parts and ratios used herein are parts by weight and ratios by weight.
| Examined unit | Big continuous police school Galvanizing plant | Motor caravan Parts factory Separate electroplating plant | Lushun iron mountain Electroplating plant | Travel prosperity reaching Water (W) Treatment plant | |
| Comprises Zinc Measurement of mg/l | To Theory of things Front side | 342 | 104 | 125 | 200 |
| To Theory of things Rear end | 0.301 | 0.8/0.64 | 0.8 | 1.17/ 0.72 | |
| Strength of adhesion | Neutral salt spray test | Appearance of the product | |
| China people Liberation army 7417 plant | Qualified | By passing | By passing |
| Travel prosperity reaching Water treatment agent plant | · | · | · |
Claims (4)
1. A zinc-plating wastewater treatment agent is characterized in that: the composition comprises the following components in percentage by weight:
caustic alkali 25-27%
2 to 4 percent of urea
1 to 2 percent of hexamethylene tetramine
2 to 6 percent of phosphoric acid or salt
1 to 3 percent of bone glue
Water surplus
2. The method for treating a zinc plating wastewater by a zinc plating wastewater treatment agent according to claim 1, characterized by:
a, detecting the concentration of zinc ions in the galvanizing waste water, adjusting the concentration not to exceed 1000mg/l,
b, adjusting the pH value of the wastewater to be between 3 and 5 by using sulfuric acid,
c, adjusting the pH value of the wastewater to 7.0-7.2 by using 15% -25% of sodium hydroxide,
d, adding 1.0-1.5 liters of treating agent into each ton of wastewater, stirring for 5-7 minutes, controlling the pH value to be 8.2-9.0 by using 15-25% sodium hydroxide solution,
e, standing for 4-16 hours, and then filtering and separating to obtain a separation liquid and a solid precipitate.
3. A method for recovering precipitates after galvanized wastewater is treated by a galvanized wastewater treatment agent is characterized by comprising the following steps:
a, adding process hydrochloric acid into the precipitate to dissolve the precipitate, filtering to remove insoluble substances,
b adjusting the pH value of the zinc-containing solution with sodium hydroxide solution, filtering to remove insoluble substances when the pH value is 4, filtering to remove insoluble substances when the pH value is 6, filtering to remove insoluble substances when the pH value is 7, filtering to collect precipitate when the pH value is 8.5,
c, washing the precipitate with deionized water or distilled water, and then dehydrating and drying at the temperature of 200-250 ℃ for 1-2 hours.
4. The method for recovering the precipitate after the treatment of the galvanizing wastewater by the galvanizing wastewater treatment agent according to claim 3, characterized in that: the concentration of sodium hydroxide for adjusting the pH value is 15-25%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 94112437 CN1048961C (en) | 1994-08-08 | 1994-08-08 | Treatment of waste galvanized water with its treating agent and method for recovery of precipitate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 94112437 CN1048961C (en) | 1994-08-08 | 1994-08-08 | Treatment of waste galvanized water with its treating agent and method for recovery of precipitate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1116611A true CN1116611A (en) | 1996-02-14 |
| CN1048961C CN1048961C (en) | 2000-02-02 |
Family
ID=5036120
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 94112437 Expired - Fee Related CN1048961C (en) | 1994-08-08 | 1994-08-08 | Treatment of waste galvanized water with its treating agent and method for recovery of precipitate |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1048961C (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101070205B (en) * | 2006-05-12 | 2010-05-12 | 北京硕泰汇丰科技有限公司 | Heavy metal ion-removing agent and preparation method thereof |
| CN101955283A (en) * | 2010-08-27 | 2011-01-26 | 山东建筑大学 | Method for recycling waste liquid from alkaline zincate zinc plating process experiment tests in laboratory |
| CN101717134B (en) * | 2009-12-04 | 2011-05-18 | 浙江师范大学 | Method for treating zinc-containing electroplating wastewater and recovering zinc by electrolysis |
| CN102874951A (en) * | 2012-09-28 | 2013-01-16 | 浙江华电器材检测研究所 | Zinc-layer uniformity test wastewater treatment equipment |
| CN106396039A (en) * | 2015-07-28 | 2017-02-15 | 江苏吉华化工有限公司 | Ammonia nitrogen removing fine chemical industry wastewater treatment agent |
| CN108046307A (en) * | 2017-12-18 | 2018-05-18 | 东北大学 | A kind of waste water extraction zinc of iron content containing zinc and the method for preparing zinc oxide |
| CN116477785A (en) * | 2023-03-29 | 2023-07-25 | 上海永丰热镀锌有限公司 | Environment-friendly treatment method for heavy metal ion wastewater |
-
1994
- 1994-08-08 CN CN 94112437 patent/CN1048961C/en not_active Expired - Fee Related
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101070205B (en) * | 2006-05-12 | 2010-05-12 | 北京硕泰汇丰科技有限公司 | Heavy metal ion-removing agent and preparation method thereof |
| CN101717134B (en) * | 2009-12-04 | 2011-05-18 | 浙江师范大学 | Method for treating zinc-containing electroplating wastewater and recovering zinc by electrolysis |
| CN101955283A (en) * | 2010-08-27 | 2011-01-26 | 山东建筑大学 | Method for recycling waste liquid from alkaline zincate zinc plating process experiment tests in laboratory |
| CN101955283B (en) * | 2010-08-27 | 2012-05-23 | 山东建筑大学 | Method for recycling waste liquid from laboratory alkaline zincate galvanizing process test |
| CN102874951A (en) * | 2012-09-28 | 2013-01-16 | 浙江华电器材检测研究所 | Zinc-layer uniformity test wastewater treatment equipment |
| CN102874951B (en) * | 2012-09-28 | 2014-02-05 | 浙江华电器材检测研究所 | Zinc-layer uniformity test wastewater treatment equipment |
| CN106396039A (en) * | 2015-07-28 | 2017-02-15 | 江苏吉华化工有限公司 | Ammonia nitrogen removing fine chemical industry wastewater treatment agent |
| CN108046307A (en) * | 2017-12-18 | 2018-05-18 | 东北大学 | A kind of waste water extraction zinc of iron content containing zinc and the method for preparing zinc oxide |
| CN116477785A (en) * | 2023-03-29 | 2023-07-25 | 上海永丰热镀锌有限公司 | Environment-friendly treatment method for heavy metal ion wastewater |
| CN116477785B (en) * | 2023-03-29 | 2024-07-09 | 上海永丰热镀锌有限公司 | Environment-friendly treatment method for wastewater generated in hot galvanizing production process |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1048961C (en) | 2000-02-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101157509A (en) | Electroplating wastewater zero-discharge or low-discharge handling method | |
| CN104310647A (en) | Recycling method for treating stainless steel pickling acid pickle and wastewater | |
| CN102452743A (en) | Method for treating complex-containing nickel plating wastewater | |
| US4210530A (en) | Treatment of metal plating wastes with an unexpanded vermiculite cation exchange column | |
| CN105174661A (en) | Acid-pickled phosphatized wastewater treatment process | |
| DE3301310C2 (en) | ||
| CN101580317A (en) | Nickel-containing wastewater treatment technology | |
| CN113526752B (en) | Method for recycling copper and phosphorus resources in pyrophosphoric acid copper plating wastewater | |
| WO2017080164A1 (en) | Electroplating waste water processing process | |
| CN1048961C (en) | Treatment of waste galvanized water with its treating agent and method for recovery of precipitate | |
| CN107892339B (en) | Preparation and application of aquatic product sewage treatment agent | |
| CN107056388A (en) | The preparation method of chemical polishing waste phosphoric acid processing method and fertilizer | |
| CN1104384C (en) | Control method of waste water containing chromium | |
| CN1669955A (en) | Waste water treatment process in fluorobenzene production | |
| US5460730A (en) | Process and apparatus for treating wastewater from lead battery production | |
| DE2724724A1 (en) | METHOD AND DEVICE FOR RECOVERY OF HEAVY METALS FROM WATER | |
| CN106148709B (en) | Nickel recovery and treatment method in chemical nickel plating waste solution | |
| Hoover et al. | Disposal of waste liquors from chromium plating | |
| GB2113199A (en) | Detoxication of industrial waste | |
| CN116477785B (en) | Environment-friendly treatment method for wastewater generated in hot galvanizing production process | |
| CN1974877A (en) | Waste chromium plating solution treating process | |
| CN111039459A (en) | Treatment process of nickel-deplating wastewater containing m-sodium nitrobenzenesulfonate | |
| CN111807588A (en) | Ion exchange-based emission reduction and treatment technology for electroplating heavy metal wastewater | |
| CN113912225B (en) | Method for treating and recycling wastewater containing copper coke | |
| CN210419542U (en) | Phosphorite ore dressing effluent disposal system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C06 | Publication | ||
| PB01 | Publication | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |