CN1994929A - High-concentration chromium-containing wastewater resource treatment method - Google Patents

High-concentration chromium-containing wastewater resource treatment method Download PDF

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Publication number
CN1994929A
CN1994929A CN 200610095376 CN200610095376A CN1994929A CN 1994929 A CN1994929 A CN 1994929A CN 200610095376 CN200610095376 CN 200610095376 CN 200610095376 A CN200610095376 A CN 200610095376A CN 1994929 A CN1994929 A CN 1994929A
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waste water
absorption tower
chromium
concentration
level
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CN100509658C (en
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吴继明
罗华正
王永红
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Environment Protection Research Institute logistical Engineering University Of P
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Environment Protection Research Institute logistical Engineering University Of P
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Abstract

The invention discloses a processing method of high-density chrome wastewater without impurity and secondary pollution, which is characterized by the following: alkalizing; acidifying the chrome wastewater; aerating high-density sulfur dioxide gas into low-density chrome waste water; exchanging once; aerating low-density sulfur oxide gas into high-density chrome wastewater; finishing adsorbing completely; detecting Cr6+ lower than 0.5PPM; adding in the neutralizing pond of alkali liquid; adjusting pH value to 7-8; reacting to generate chrome hydroxide; sedimenting; dehydrating through filter press; obtaining rough product of chrome hydroxide; filtering the waste water deeply to reach draining standard.

Description

High-concentration chromium-containing wastewater resource treatment method
Technical field
The present invention relates to a kind of method of sewage disposal, particularly a kind of high-concentration chromium-containing wastewater resource treatment method.
Background technology
Chromic salts industry is the important inorganic chemical industry industry of China, and the chromium slag produces 2～3 tons of slag dischargings with 1 ton of product of every production.Along with the construction of layouting in the whole nation of domestic chromium salt factory, the whole nation has nearly more than 2,000,000 tons of chromium slags to store up under any seepage control measure situation not taking, and causes the underground water severe contamination.In addition, the chromic salts ordinary production also must have a large amount of chromate waste waters to discharge in order to prevent the enrichment in technology of silicon, chlorine, calcium, iron, aluminium.The processing of chromium salt production waste water, chromium slag being oozed draining has a large amount of research both at home and abroad, as biochemical process, iron filings method, ferrous sulfate, sodium bisulfite or Sodium Pyrosulfite method etc.Qualified discharge is a purpose after the wastewater treatment but these method practical applications are all taked, complex process not only in actual motion, and the chromium-bearing sludge processing also being included in, and danger is useless to be handled, running cost is up to 25～30 yuan of/ton wastewater treatments, trivalent chromium after the processing is impure also to be mixed with impurity such as iron, causes actual intractability big.The sulfurous gas method is a best-of-breed technology of realizing that at present high-concentration chromium-containing wastewater resource is handled, and existing sulfurous gas law technology flow process in treating processes is discontinuous, and it is impure to handle the back trivalent chromium, and used sulfurous gas can cause secondary pollution again.
Summary of the invention
At above-mentioned technical problem, the invention provides a kind of technical process continuously, handle that the back trivalent chromium is free from foreign meter, the high-concentration chromium-containing wastewater resource treatment method of non-secondary pollution.
Concrete technical scheme is as follows:
A kind of high-concentration chromium-containing wastewater resource treatment method may further comprise the steps successively:
(1) the alkalization chromate waste water adds sodium hydroxide at wastewater equalization pond in waste water, makes itself and iron and other basic metal in the waste water fully react and generate the throw out be insoluble in water, the removal throw out;
(2) the acidifying chromate waste water adds sulfuric acid at acidification pool in waste water, regulates PH to 4～5,, reacts with low-concentration sulfur dioxide to one-level waste water absorption tower with the pressure pump pump;
(3) treat that one-level waste water absorption tower reaction is finished after, sulfur furnace burns sulphur for 800 ℃～1000 ℃ in temperature, the high density sulfur dioxide gas feeding that produces is equipped with in the secondary waste water absorption tower of acidified waste water, one-level absorbs and switches to secondary, the low-concentration sulfur dioxide that comes out from the two-level absorption tower top enters the first grade absorption tower bottom, after first grade absorption tower and high-concentration chromium-containing wastewater reaction, unnecessary sulfur dioxide gas is inhaled top of tower from one-level and is come out to enter tail gas absorber, is absorbed in containing the tail gas absorber of sodium hydroxide and the sodium bisulfite that produces is returned first grade absorption tower utilize; The waste water of processed two-level absorption tower injects neutralization tank;
(4) successively add alkali lye, flocculation agent adjusting PH to 7～8 in neutralization tank, dosing pond, reaction generates chromium hydroxide and enters the further post precipitation of tube settler, further dewaters with pressure filter again, obtains the chromium hydroxide crude product; Waste water enters deep filter, makes its qualified discharge.
Wherein step (2) is that the high density sulfur dioxide gas is led in the chromate waste water of lower concentration, will lead in the chromate waste water of high density through the low-concentration sulfur dioxide gas after once exchanging.
Wherein the gas that comes out from sulfur furnace of step (3) is removed to rise through laveur and is sent out a sulphur, cools off through water cooler again.
Wherein the described flocculation agent of step (4) is various organic floculants.
Step of the present invention (1) is the alkalization high-concentration chromium-containing wastewater earlier, and throw outs such as iron wherein and other basic metal and NaOH reaction generation ironic hydroxide discard, and this has just removed impurity effectively, and the trivalent chromium after guaranteeing to handle is free from foreign meter.
In sulfur furnace, produce SO by sulfur burning 2Be mixed with the sulphur of distillation simultaneously, so preferably handle the SO of this moment earlier through laveur 2Gas temperature is higher, can feed in the two-level absorption tower after the water cooler cooling again.The SO that sulfur furnace comes out 2The concentration of gas is 3%-10%.
Under acidic conditions, use SO 2In the high-concentration chromium-containing wastewater absorption tower, reduce Cr 6+, and make it to form Cr (OH) with liquid caustic soda neutralization 3Precipitation, reaction formula is:
Na 2Cr 2O 7+3SO 2+H 2SO 4→Cr 2(SO 4) 3+Na 2SO 4+H 2O (1)
Cr 2(SO 4) 3+6NaOH→2Cr(OH) 3↓+3Na 2SO 4 (2)
Excessive SO 2Part exists in solution with the sulfurous acid form, in and the time with liquid caustic soda effect generation S-WAT, in air, can be oxidized to sodium sulfate gradually, reaction formula is:
H 2SO 3+2NaOH→Na 2SO 3+3H 2O (3)
Na 2SO 3+0.5O 2→Na 2SO 4 (4)
All the other excessive SO 2Enter tail gas absorber, this part SO with gas form with the tail gas discharge 2The employing liquid caustic soda absorbs, and the sodium bisulfite of generation returns one-level and absorbs, and continues and the sexavalent chrome reaction, and reaction formula is as follows:
2Na 2Cr 2O 7+6NaHSO 3+5H 2SO 4→2Cr 2(SO 4) 3+5Na 2SO 4+SH 2O (5)
Calculate equilibrium constant of reaction according to electrochemical electrode potential method, computation process is as follows:
Above-mentioned reaction can be decomposed into the galvanic cell reaction of anode and negative electrode, and its Standard Electrode Potentials is:
Cr 2O 7 2-+14H ++6e＝2Cr 3++7H 2O E＝1.33v
SO 2+H 2O-2e＝SO 4 2-+4H + E＝0.17v
Reaction formula after the merging is
Cr 2O 7 2-+2H ++3SO 2＝2Cr 3++4H 2O+3SO 4 2- E 0＝1.16v
Be similar to actual condition with standard state, relevant because of the free energy of reaction with the equilibrium constant, under the influence of ignoring temperature counter electrode electromotive force, have following relationship to set up:
ΔG 0＝-nE 0F＝-RTlnK
lnK＝nE 0F/RT＝6×1.16×96485/(8.3144×298)＝271.03
The equilibrium constant is
K＝5.1×10 117
And K=[Cr 3+] 2[H 2O] 4[SO 4 2-] 3/ [Cr 2O 7 2-] [H +] 2[SO 2] 3
Suppose that initial concentration is Cr 6+1000ppm, temperature of reaction is normal temperature (25 ℃).And SO 2Be in state of saturation, with SO always 4 2-Concentration is equal substantially.
[Cr 2O 7 2-]＝6.76×10 -115/[H +] 2
When pH=2, [H +]=0.01mol/l
[Cr 2O 7 2-]＝6.76×10 -111mol/l→0ppm
When pH=5, [H +]=0.00001mol/l
[Cr 2O 7 2-]＝6.76×10 -105mol/l→0ppm
Prove that theoretically this reaction can thoroughly carry out, and the pH value does not influence the carrying out of reaction under acidic conditions.
To being compared as follows of working cost;
(1), the working cost of using sulfur dioxide reduction method of the present invention is as follows:
Sulphur consumes: 1.3 kg/kg Cr 6+
Sulfuric acid consumption: 0.1 kilogram of/ton waste water (the pH value is owing to have only 4～5)
The consumption of alkali: 3.0 kilogram of 40% caustic soda/ton waste water
Cost of raw and processed materials:
1.3 * 0.6 * 1.0+0.1 * 0.5+3.0 * 0.7=2.93 unit/ton
Add power and labour cost, total processing cost is about 6.5 yuan/ton.
(2) the operation raw material cost of sodium bisulfite method
1.3kg sodium bisulfite/kg sodium dichromate 99, convert for sexavalent chrome be 3.7kg sodium bisulfite/kgCr 6+(theoretical consumption is 3 kilograms)
Sulfuric acid consumption is: the pH value was controlled at 2 o'clock, and theoretical consumption of vitriolic is 0.49 kilogram of/ton waste water, and the pH value was controlled at 1 o'clock, and theoretical consumption of vitriolic is 4.9 kilograms of/ton waste water, 2 kilograms of/ton waste water consumption of value.
The consumption of alkali is: 3 kilograms of 100%NaOH/ ton waste water, rolling over 40% concentration is 7.5 kilograms of/ton waste water.
Raw material total expense is about:
0.6 (waste water content is the Cr of 600mg/l to * 3.7 * 2.0+2 * 0.5+7.5 * 0.7=12.2 unit/ton waste water 6+)
About 7 yuan/ton of power and labour cost.
Add up to 19 yuan/ton of overall running costs.
(3) iron filings method working cost
The people live in plenty in Chongqing, and farmingization group built 20000 tons of/year sodium dichromate matched with devices in 1999 has built 400 tons of high-concentration waste waters of daily handling ability, reach 27 yuan of/ton waste water through working cost, and concentration of treatment waste water sexavalent chrome is below 200mg/l, if high-concentration waste water must dilute aftertreatment, its waste residue is included the useless management of danger in, and handling per ton is 2000 yuan.By above comparison, the method for the invention greatly reduces cost.
The invention has the beneficial effects as follows that a kind of technical process is continuous, processing back trivalent chromium is free from foreign meter, chromate waste water utilized as resource again that produce chromium hydroxide free from foreign meter, discharge of wastewater is up to standard.Non-secondary pollution has been realized the high-concentration chromium-containing wastewater utilization of resources, kills two birds with one stone.And processing cost reduces greatly.
Description of drawings
Fig. 1 is a process flow sheet of the present invention
Specific embodiment
Do detailed explanation below in conjunction with process flow sheet:
The water of making from the wastewater collection pump changes over to the wastewater equalization pond, and alkalization waste water removes de-iron and other basic metal earlier, and is behind the disgorging, with transfering material pump that the circulatory pool that waste water pumps into wastewater treatment is stand-by.Acidification pool with waste water earlier with sulfuric acid acidation to pH4～5, pump is to one-level waste water absorption tower, from top spray down, with through the low-concentration sulfur dioxide gas after the exchange once after contact reacts on the liquid film of filler, return and flow into former circulatory pool.After treating that the reaction of one-level waste water absorption tower is finished, one-level absorbs and switches to secondary, and the chromate waste water that comes out from one-level waste water absorption tower enters a circulatory pool, and pump is to two-level absorption tower and the high density SO that comes out from sulfur furnace again 2Reaction is to guarantee Cr 6+Be reduced fully.And the SO that in sulfur furnace, produces by sulfur burning 2Deliver to secondary waste water absorption tower and waste water reaction through roots blower, come out to enter the first grade absorption tower bottom again from the two-level absorption tower top, after first grade absorption tower and high-concentration chromium-containing wastewater reaction, inhale top of tower from one-level and come out to enter tail gas absorber.Tail gas absorber also adopts caustic soda sodium hydroxide to absorb, and caustic soda is same the same with waste water, is to spray top into tower by circulatory pool by pump, guarantees remaining SO 2Be absorbed fully, this has just effectively solved secondary pollution problem, and emission gases is up to state standards.Detect Cr in the waste water 6+When being lower than 0.5PPM, sump pump to neutralization tank, is neutralized to PH7～8 with alkali lye, forms Cr (OH) 3Precipitation adds flocculation agent in the dosing pond and clarifies through inclined tube, and belt is filtered, and standard compliant clear water is discharged Cr (OH) after deep filter is handled 3Filter mud is recycled.

Claims (4)

1. high-concentration chromium-containing wastewater resource treatment method may further comprise the steps successively:
(1) the alkalization chromate waste water adds sodium hydroxide at wastewater equalization pond in waste water, makes itself and iron and other basic metal in the waste water fully react and generate the throw out be insoluble in water, the removal throw out;
(2) the acidifying chromate waste water adds sulfuric acid at acidification pool in waste water, regulates PH to 4～5,, reacts with lower concentration oxidation sulphur to one-level waste water absorption tower with the pressure pump pump;
(3) treat that one-level waste water absorption tower reaction is finished after, sulfur furnace burns sulphur for 800 ℃～1000 ℃ in temperature, the high density sulfur dioxide gas feeding that produces is equipped with in the secondary waste water absorption tower of acidified waste water, one-level absorbs and switches to secondary, the low-concentration sulfur dioxide that comes out from the two-level absorption tower top enters the first grade absorption tower bottom, after first grade absorption tower and high-concentration chromium-containing wastewater reaction, unnecessary sulfur dioxide gas is inhaled top of tower from one-level and is come out to enter tail gas absorber, is absorbed in containing the tail gas absorber of sodium hydroxide and the sodium bisulfite that produces is returned first grade absorption tower utilize; The waste water of processed two-level absorption tower injects neutralization tank;
(4) successively add alkali lye, flocculation agent adjusting PH to 7～8 in neutralization tank, dosing pond, reaction generates chromium hydroxide and enters the further post precipitation of tube settler, further dewaters with pressure filter again, obtains the chromium hydroxide crude product; Waste water enters deep filter, makes its qualified discharge.
2. high-concentration chromium-containing wastewater resource treatment method as claimed in claim 1, wherein the gas that comes out from sulfur furnace of step (3) is removed to rise through laveur and is sent out a sulphur.
3. high-concentration chromium-containing wastewater resource treatment method as claimed in claim 2, wherein the gas that comes out from sulfur furnace of step (3) is removed to rise through laveur and is sent out a sulphur, cools off through water cooler again.
4. high-concentration chromium-containing wastewater resource treatment method as claimed in claim 1, wherein the described flocculation agent of step (4) is an organic floculant.
CNB2006100953760A 2006-12-29 2006-12-29 High-concentration chromium-containing wastewater resource treatment method Expired - Fee Related CN100509658C (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102229455A (en) * 2011-05-31 2011-11-02 重庆民丰化工有限责任公司 Process for processing chromate-containing waste water
CN101618902B (en) * 2008-11-04 2011-11-09 刘文治 Zero emission treatment method of completely turning chromium-containing waste liquor into useable resources.
CN102320697A (en) * 2011-05-31 2012-01-18 重庆民丰化工有限责任公司 Desulfuration process for chromate waste water
CN104049565A (en) * 2014-05-26 2014-09-17 范振捷 Method for controlling industrial wastewater level
CN106890554A (en) * 2017-03-24 2017-06-27 安徽宣城金宏化工有限公司 The handling process and equipment of acid Process Gas during a kind of carbon disulphide production
CN108128923A (en) * 2017-12-23 2018-06-08 安徽睿知信信息科技有限公司 Process for processing chromate-containing waste water in a kind of chromic salts and chromium compounds production
CN110642430A (en) * 2019-10-31 2020-01-03 重庆雅丽洁环保产业发展有限公司 Treatment process of chromium-containing wastewater

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1003785B (en) * 1986-04-30 1989-04-05 北京市大兴县环境保护局 Process for treating chromium-plating sewage by sulphate dioxide
CN1695774A (en) * 2005-04-14 2005-11-16 丁建础 Method for eliminating sulfur dioxide in fume

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101618902B (en) * 2008-11-04 2011-11-09 刘文治 Zero emission treatment method of completely turning chromium-containing waste liquor into useable resources.
CN102229455A (en) * 2011-05-31 2011-11-02 重庆民丰化工有限责任公司 Process for processing chromate-containing waste water
CN102320697A (en) * 2011-05-31 2012-01-18 重庆民丰化工有限责任公司 Desulfuration process for chromate waste water
CN104049565A (en) * 2014-05-26 2014-09-17 范振捷 Method for controlling industrial wastewater level
CN106890554A (en) * 2017-03-24 2017-06-27 安徽宣城金宏化工有限公司 The handling process and equipment of acid Process Gas during a kind of carbon disulphide production
CN108128923A (en) * 2017-12-23 2018-06-08 安徽睿知信信息科技有限公司 Process for processing chromate-containing waste water in a kind of chromic salts and chromium compounds production
CN110642430A (en) * 2019-10-31 2020-01-03 重庆雅丽洁环保产业发展有限公司 Treatment process of chromium-containing wastewater

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