CN1105953A - Method and equipment of treating waster chromium-plating water under alkaline condition - Google Patents
Method and equipment of treating waster chromium-plating water under alkaline condition Download PDFInfo
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- CN1105953A CN1105953A CN 94100739 CN94100739A CN1105953A CN 1105953 A CN1105953 A CN 1105953A CN 94100739 CN94100739 CN 94100739 CN 94100739 A CN94100739 A CN 94100739A CN 1105953 A CN1105953 A CN 1105953A
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- chromium
- under alkaline
- alkaline condition
- waste water
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Abstract
Under alkaline condition, Cr-containing waste electroplating solution reacts with assistant as well as ferrous salt reducing agent to proceed redox reaction so as to complete the reduction of 6-valence Cr ions and the flocculation of heavy metal ions in one step. The process features low cost, simple technological route and high volume flow speed up to 20-30/hr.
Description
The present invention relates to a kind of method and apparatus of from waste water, removing heavy metal ion.
In the prior art, make reductive agent processing electroplating wastewater of chromium with ferrous salt and all carry out under acidic conditions, promptly generally controlling pH value is 2-3, makes the hexavalent chrome reduction in the waste water become trivalent chromium, again pH value is increased to 8-9 after the reduction, so that trivalent chromium and other heavy metal ion precipitation.Because the pH value of general electroplating wastewater of chromium all is higher than 2-3, the waste water of some chromium salt factory then is neutrality even meta-alkalescence, therefore adopt prior art all to need to add acid earlier before such reduction pH value is reduced to 2-3, add alkali after the reduction again pH value is increased to the repetitive process of 8-9, will cause the waste of medicament and the complexity of technology undoubtedly.
The stirring through certain hour in reactor of the redox reaction of prior art is carried out, required ferrous salt reducing agent need by independent setting join groove and pump is supplied with, reactor must be taked anti-corrosion measure, when its volumetric flow rate only is 1-3/, and also needing configuration respectively to be used to regulate acid tank and sour pump, alkali groove and the alkali pump of pH value before and after the reactor, the flocculation of heavy metal ion needs to carry out in the neutralization buffer pond that is provided with separately.Therefore, prior art exists the shortcoming that technical process is long, equipment is complicated, the processing power of equipment is low, be difficult to operate continuously.
The objective of the invention is to overcome the above-mentioned weak point of prior art, a kind of method that can directly handle electroplating wastewater of chromium under alkaline condition is provided, flocculation one step of chromic reduction and heavy metal ion is finished, and provide a kind of simple in structure, processing power big, be easy to the treating plant of operate continuously.
The object of the present invention is achieved like this:
Waste water directly enters cleaner under alkaline condition, contact with wherein auxiliary agent, ferrous salt reducing agent and carry out redox reaction, and the trivalent chromium that is reduced simultaneously and other heavy metal ion generate cotton-shaped sediment, then further precipitation, solid-liquid separation.
Implementing aforesaid method of the present invention only needs to add alkali and makes its pH value bring up to the suitable numerical value of 7-14 (concrete pH value determines what by the content of sexavalent chrome in the waste water and other heavy metal ion) before waste water enters cleaner.Used reductive agent can be ferrous sulfate, iron protochloride etc.Quality and chromic mass ratio that the control reductive agent enters water body are (Fe
2+)/(Cr
6+)=3.3-5.6.
The adjuvant used component of method of the present invention is lime, aluminium salt, magnesium salts, polysulfide and tackiness agent.
In the component of above-mentioned auxiliary agent: lime can be the slaked lime of moisture 40-60%; Aluminium salt can be aluminum chloride, Tai-Ace S 150; Magnesium salts can be magnesium chloride, sal epsom; Polysulfide can be calcium polysulfide, sodium polysulphide; Tackiness agent can be polyvinyl alcohol water solution, water glass, carboxymethyl cellulose etc.
The adjuvant used composition weight % of the present invention can be: lime 85-95, aluminium salt is (with Al
3+Meter) 0.1-10, magnesium salts 0.1-5, polysulfide 0.1-10, tackiness agent 1-10.
The ultimate principle of foundation of the present invention is: the prerequisite that redox processes is carried out is that the right current potential of oxygenant electricity will be higher than the right current potential of reductive agent electricity, under the normal conditions by standard oxidationreduction potential E
0Judge, under different hydro ionic concn (pH value) condition, judge by formal potential (being the condition redox potential again) φ.Usually people only notice that sexavalent chrome has very strong oxidisability under acidic conditions, its redox potential is far above ferrous current potential under the identical conditions, and ignored variation along with hydrogen ion concentration, the current potential of redox couple also has corresponding variation, promptly under alkaline condition, the electricity to Cr(VI-III) current potential and the electricity to Fe(III-II) current potential all be lower than its standard oxidationreduction potential, and the electricity to Cr(VI-III) current potential always greater than electricity to Fe(III-II) current potential, be Φ Cr(VI-III)＞Φ Fe(III-II), therefore, the ferrous salt reduction of hexavalent chromium is feasible in theory under alkaline condition.
The effect of auxiliary agent is to make the ion of its release with the Fe in the solution
3+, Cr
3+And Me
2+Form rapidly precipitation, impel reaction to carry out to the right, and in the flocculating settling of back operation, play absorption, help with fixed attention, help heavy effect.
The chemical reaction that the present invention relates to following (PH＞7):
Above-mentioned reaction formula 3.-6. in, three kinds of throw outs of generation are all than CaCrO
4, Ca(OH)
2Indissoluble is separated, and therefore reaction is carried out to the right.Illustrate also simultaneously that the redox reaction under alkaline condition is a consumption (OH
-) the ionic process, the pH value of reaction back waste water descends, therefore, waste water enter pH value before the cleaner actual should be controlled at heavy metal ion is precipitated fully and should make processing after the suitable numerical value of water ph value allow compliance with emission standards.
The present invention is a cleaner for the treating plant that the enforcement aforesaid method provides, it has a columniform reducer [3], the lower cover [8] that its bottom is equipped with water distribution board [7] and is provided with water inlet pipe [9], the material feeder [1] of uniform aperture on the wall is equipped with at its top, and semi-circular rising pipe [5] is positioned at the reducer first half.
Fig. 1 is the structural representation of cleaner;
Fig. 2 is the A-A sectional view of Fig. 1;
Fig. 3 is a process flow diagram of the present invention.
See figures.1.and.2, waste water enters clarifier by water inlet pipe 9, contacts through water distributing plate 7 even risings and with filler one auxiliary agent of reductor 3 interior bottoms, make it dissolve different kinds of ions, then continuing rises contacts with dispenser 1, and the dispenser wall is evenly equipped with φ 5 apertures, liner 240＃Filter cloth, reducing agent are packed into wherein, and reducing agent dissolve, permeates, is diffused in the water body when wastewater streams is around the dispenser, makes Cr VI be reduced to rapidly trivalent chromium under the condition of PH＞7, simultaneously trivalent chromium and other heavy metal ion formation heavy metal floccule body. The dissolution velocity of reducing agent can be controlled by the thickness of filter cloth, the height of liquid level, the height of liquid level is by liquid level meter 2 and overflow pipe 4 and outlet pipe 5 controls, the excessive water sample with not passing through check outlet pipe 5 completely of reducing agent, whether judge fully depending on hexavalent chrome reduction, and excessive what can be by check Fe2+How much coming of ion is definite, general control Fe2+Excessive is the 5-10% of theoretical amount. Under the substantially constant condition of inflow, hexavalent chromium concentration, temperature, be stably operable after debugging by above regulation. When discharging valve 6 is used for stopping the waste water in the equipment is emitted.
With reference to Fig. 3, workshop waste water flows into collecting-tank 10, squeezes into clarifier 13 by intake pump 11, and inflow is controlled by flowmeter, open the outlet valve of alkali groove 12, according to the concentration adjustment water inlet PH=7-14 of Cr VI in the waste water and other heavy metal ion, got final product by the outlet pipe check PH=7-8 of clarifier. Waste water enters inclined plate sedimentation pond 14 by the outlet pipe on clarifier top after finishing the reduction flocculation process through clarifier, and after sedimentation separation, the top clear water flows into sand filter 17 from collector pipe, clear water or reuse or discharging after further filtering. The mud of inclined plate sedimentation pond bottom is regularly squeezed into plate and frame filter press 16 by screw pump 15, the clear water after the press filtration or discharging or advance again sand filter and filter, and body refuse remakes harmless processing.
Subordinate list is processed the comparison of waste water experimental result for the method for utilizing respectively method provided by the invention and prior art. Processing method I in the table is method provided by the invention, i.e. ferrous salt and auxiliary agent thereof reduction of hexavalent chromium and simultaneously sedimentation heavy metal ion under alkali condition; Treatment II is the method for prior art, and namely then ferrous salt reduction of hexavalent chromium under acid condition regulates PH to 8-9 sedimentation heavy metal ion with calcium hydroxide; Fe in two kinds of methods2+All excessive 10%. "/" shown in the table refers to not detect (being limited to 0.01mg/L under the detection of used atomic absorption spectrum).
The experimental result explanation of subordinate list:
(1), method provided by the invention can be processed under the condition of PH=7-14 and contain Cr6+Concentration up to 400mg/L, contain other heavy metal ion (such as Cu2+、Zn
2+、Ni
2+Deng) concentration also can be about 100mg/L comprehensive electroplating wastewater, the indexs such as the pH value of processed waste water and heavy metal ion all meet discharging standards.
(2), the heavy metal ions in wastewater after processing with the inventive method o'clock almost completely precipitates in PH 〉=6.3, do not detect with atomic absorption spectrum, and the waste water after processing with prior art has the residual heavy metal ion of part in PH=8.5 fashion, and the auxiliary agent that the present invention's employing be described has and helps heavy, absorption, Coagulation aiding.
(3), when the volume flow rate of the inventive method device therefor-clarifier is 25-30/, the waste water of processing all can meet discharge standard, and the volume flow rate of prior art equipment is when only being 1-3/.
The present invention contrasts that prior art has the following advantages and good effect:
Method provided by the invention has broken through prior art must be in the traditional handicraft of reduction of hexavalent chromium under the acid condition, providing a kind of directly makes chromic reduction and makes trivalent chromium and process that one step of the flocculation of other heavy metal ion finishes under alkali condition, the repetitive process that adds alkali adjusting pH value after the prior art elder generation acid adding is reduced to the disposable alkali that adds, save the part acid that adds first and be the required alkali of this part acid of neutralization, therefore the expense of institute's with medicament only is 1/5-1/2 of prior art, and simplified simultaneously technological process, disposable construction investment only is 3/5 of prior art, and daily running expense can reduce half.
Capital equipment clarifier provided by the invention is simple in structure, disposal ability is large, because redox reaction speed is exceedingly fast, time of staying 2-3 minute namely enough, so waste water passes through clarifier with 20-30 volume flow doubly, namely per hour the disposal ability of equipment be equivalent to equipment volume 20-30 doubly, be higher than the device processes ability of prior art far away.
Describe the present invention below in conjunction with embodiment:
Embodiment one:
Get Tai-Ace S 150 (with Al
3+Meter) 2kg, 10% polyvinyl alcohol water solution 10kg, calcium polysulfide 1kg, magnesium chloride 2kg, moisture 50% slaked lime 200kg stirs above several components, be squeezed into φ 20 balls, under 80-100 ℃ of temperature the oven dry or at room temperature dry, be the finished product auxiliary agent.
Embodiment two:
In certain electroplating wastewater 2-3 of factory ton/time,, PH=5-6 contains Cr in the waste water
6+50-80mg/L, Zn
2+30-50mg/L, Cu
2+50-100mg/L, Ni
2+100-150mg/L, waste water enter and add liquid caustic soda control PH=9-11 before the cleaner, and during the volumetric flow rate S=30/ of cleaner, waste water PH=7.5 after environmental administration's sampling Detection purifies contains Cr
Always0.244mg/L, Cr
6+0.002mg/L, Zn
2+0.283mg/L, Cu
2+0.025mg/L, Ni
2+0.132mg/L, (above numerical value is the mean value of sampling Detection several times), all allow compliance with emission standards.
Embodiment three:
In certain waste water 2-3 of factory ton/time,, PH=6-7 contains Cr in the waste water
6+200-250mg/L, Zn
2+50-70mg/L, Cu
2+40-80mg/L, Ni
2+80-120mg/L, waste water enter and add liquid caustic soda control PH=12-13 before the cleaner, and during the volumetric flow rate S=27/ of cleaner, waste water PH=7.2 after environmental administration's sampling Detection purifies contains Cr
Always0.203mg/L, Cr
6+0.023mg/L, Zn
2+0.211mg/L, Cu
2+0.321mg/L, Ni
2+0.271mg/L, equal allow compliance with emission standards.
Subordinate list
Claims (4)
1, a kind of method of under alkaline condition, handling electroplating wastewater of chromium, it is characterized in that waste water directly enters cleaner under alkaline condition, contact with wherein auxiliary agent, ferrous salt reducing agent and to carry out redox reaction, the trivalent chromium that is reduced simultaneously and other heavy metal ion generate cotton-shaped sediment, then further the precipitation, solid-liquid separation.
2, the method for claim 1 is characterized in that adjuvant used component is lime, aluminium salt, magnesium salts, polysulfide and tackiness agent.
3, method as claimed in claim 1 or 2, it is characterized in that adjuvant used composition weight % is: lime 85-95, aluminium salt is (with Al
3+Meter) 0.1-10, magnesium salts 0.1-5, polysulfide 0.1-10, tackiness agent 1-10.
4, a kind for the treatment of plant of implementing the described method of claim 1, it is characterized in that this cleaner has a columniform reducer [3], the lower cover [8] that its bottom is equipped with water distribution board [7] and is provided with water inlet pipe [9], the material feeder [1] of uniform aperture on the wall is equipped with at its top, and semi-circular rising pipe [5] is positioned at the reducer first half.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 94100739 CN1105953A (en) | 1994-01-25 | 1994-01-25 | Method and equipment of treating waster chromium-plating water under alkaline condition |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 94100739 CN1105953A (en) | 1994-01-25 | 1994-01-25 | Method and equipment of treating waster chromium-plating water under alkaline condition |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1105953A true CN1105953A (en) | 1995-08-02 |
Family
ID=5029809
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 94100739 Pending CN1105953A (en) | 1994-01-25 | 1994-01-25 | Method and equipment of treating waster chromium-plating water under alkaline condition |
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|---|---|
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1098913C (en) * | 2000-01-04 | 2003-01-15 | 中国石油化工集团公司 | Hydrogenating catalyst and its preparing process |
| CN101234828B (en) * | 2008-02-19 | 2011-05-11 | 天津大学 | Integrated electroplating treatment method for waste water |
-
1994
- 1994-01-25 CN CN 94100739 patent/CN1105953A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1098913C (en) * | 2000-01-04 | 2003-01-15 | 中国石油化工集团公司 | Hydrogenating catalyst and its preparing process |
| CN101234828B (en) * | 2008-02-19 | 2011-05-11 | 天津大学 | Integrated electroplating treatment method for waste water |
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