CN1007041B - Comprehensive treatment method for sulfur dioxide-containing waste flue gas and cyanide-containing waste water - Google Patents

Abstract

Containing SO₂The comprehensive treatment method of waste flue gas and cyanide-containing waste water is characterized by that the two are passed through a filler reaction tower to forcedly implement gas-liquid countercurrent mass transfer, and directly interact to implement chemical reaction, and the copper sulfate is used as catalyst, and the alkaline solution is used to regulate pH value of reaction. The method treats waste with waste, achieves two purposes by one action, and can treat 2500-3000 m by using the waste water when treating one ton of high-cyanogen waste water³Containing SO₂The total required cost of the waste flue gas is only 0.182 yuan, and the method has obvious economic benefit and environmental benefit.

Description

Comprehensive processing method for cyanogen-contg. waste water and SO2-contg. exhaust flue gas

The invention belongs to waste gas and wastewater processing technology, particularly contain SO ₂Useless flue gas and the improvement method of cyanide wastewater.

Contain SO ₂Useless flue gas and the cyanide wastewater important source of pollution that are some manufacturing enterprises.For example iron and steel enterprise, particularly ferromanganese enterprise, the ferromanganese blast furnace Coal-gas Washing Water Using contains the prussiate of high density, contains SO in the sinter fume ₂Etc. objectionable impurities, they have seriously polluted environment, press for improvement.Prior art is all handled respectively this class waste gas and waste water.The two is utilized mutually, and the treatment of wastes with processes of wastes against one another does not appear in the newspapers its technology of being administered simultaneously so far, does not more have the precedent of application." SO by the invention of Canadian Yin Ke Allied Corp. (US) Law Department P.O. Box 2245R. Morristown, NJ 07960-2245, U.S. ₂/ air method " method of prussiate in the removal water body of (be Yin Kefa, see your international corporation of Landor nineteen eighty-two report of survey) and United States Patent (USP) 4537686 suggestions, select golden factory waste water in order to the processing gold mine, effect is fine.But its weak point all is merely SO ₂Perhaps sulphite removes to handle cyanide wastewater as main medicament, and special air blast device need be set, and the reaction times is longer, and its result has handled water body singlely.

Purpose of the present invention aims to provide a kind of treatment of wastes with processes of wastes against one another, and the economically feasible method that above-mentioned water, gas are administered simultaneously is to simplify treatment process, to reduce processing costs.

Method of the present invention is to contain SO ₂Useless flue gas directly contact with cyanide wastewater, interact, carry out finishing chemical reaction under the condition of gas, liquid countercurrent mass transfer forcing, in reaction, make catalyzer, with the pH value of basic solution conditioned reaction with copper sulfate.

Gas is carried out in pressure, the liquid countercurrent mass transfer carries out in the filler reaction tower, and this reaction tower can be single-stage, two-stage and multistage, but under the single-stage condition, does not reach the processing standard of environmental emission requirement, at least two-stage.Cyanide wastewater enters reaction tower sprays at different levels in turn and descends from the top, and SO ₂Useless flue gas then blasts reaction tower from the bottom respectively with gas blower, and waste water added catalyzer in the past entering reaction towers at different levels, and the water outlet of the reaction towers at different levels before the last step enters adjacent next stage reaction tower after regulating the pH value with basic solution.

Basic solution can be used liming, also can use NaOH, but liming is more economical, and less to equipment, Corrosion of Pipeline.When regulating with liming, the water outlet of reaction tower is gone into settling tank after regulating, and the additional little amount of catalyst of settling tank water outlet reenters the next stage reaction tower later on and further handles, and effluxes after treatment effect is satisfied.

In said reaction tower, the SO in the flue gas ₂, O ₂With the prussiate in the waste water, under certain temperature and corresponding pH condition with Cn ²⁺Be catalyzer, will dissociate cyanogen and other metal cyanogen chromium complex are oxidized to cyanate, and then generate ammonium sulfate and hydrocarbonate.Its chemical equation is:

The hexacyanoferrate is then removed with the form of sl. sol. yellow prussiate, and other metal ion forms precipitate metal hydroxides and separates out.In reaction process, SO ₂Be oxidized to SO earlier ₃, finally the form with sulfate radical is present in the waste water.

According to above-mentioned reaction, SO ₂With O ₂The ratio of requirement is 2: 1, and the oxygen concentration of surveying in this type of flue gas is higher than this value far away, promptly meets the demands so this law directly blasts flue gas, need not air blast equipment.

Method of the present invention and effect thereof will further specify below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is the process flow sheet of present method half industry for test;

Fig. 2 is the influence of material ratio to treatment effect;

Fig. 3 is that the pH value is to removing the influence of cyanogen effect;

Fig. 4 is the technology stability test-results.

Fig. 1 sign: 1.2-is respectively I and II filler reaction tower; The 3-settling tank; 4-CuSO ₄The solution header tank; 5-basic solution header tank; The 6-pH value is regulated mixing tank; The 7-water-absorbing tank; The 8-water storing tank; 9-mixes, water-absorbing tank; The 10-surge tank; 11,12-liquid meter; The 13-sludge pump; The 14-water pump; 15-flue gas gas blower; 16-flue gas flow measuring point.

According to Fig. 1, cyanide wastewater (water quality is seen attached list) enters to be squeezed into water storing tank (8) behind the water-absorbing tank (7) and puts into and mix water-absorbing tank (9), copper-bath is got with water pump (14) after water-absorbing tank (9) mixes with waste water through putting into after liquid meter (11) metering from header tank (4), after quantifier (12) metering, enter one-level filler reaction tower (1) and spray and descend, contain SO from the top ₂Useless flue gas (composition is seen attached list) is blasted from reaction tower (1) bottom by gas blower (15), gas, liquid are purified at tower (1) internal reaction, and tail gas is from tower (1) top emptying, or emptying behind the introducing chimney, rough purification water flows into from tower (1) bottom and regulates mixing tank (6), Ca(OH) ₂After solution adds mixing tank (6) adjusting pH value from header tank (5), after water outlet is squeezed into settling tank (3) sediment with sludge pump (13), its water outlet is got with water pump (14) after replenishing little amount of catalyst, after under meter (12) metering, reenter second order reaction tower (2), blast SO from this tower bottom simultaneously ₂Useless flue gas, gas, liquid are further handled tower (2) in, after surge tank (10) is discharged whole draining, and tail gas emptying behind tower (2) top emptying or the introducing chimney.Under suitable reaction conditions, the SO in the tail gas ₂Can both reach non-pollution discharge substantially, result (seeing attached list), the CN of water outlet with the cyanogen amount that contains of whole draining ^-Clearance average out to 99.64%, SO in the tail gas ₂Average removal rate, one, two towers are respectively 99.69% and 98.87%, have good environmental benefit.

Above-mentioned technological process is subjected to multiple factor affecting, enumerates the embodiment that various influence factors is carried out analysis of experiments below again:

The influence of embodiment 1 material ratio.According to reaction formula, theoretical material ratio is SO ₂: O ₂: CN ^-=2.46: 1.23: 1, but survey O in the useless flue gas factually ₂Concentration ratio SO ₂High hundred times even thousands of times, so O ₂Be competent, material ratio can only be considered SO ₂Variation with CN.As above said, SO in theory ₂: CN ^-=2.46: 1, reaction just can be carried out thoroughly.But owing to other factors interference in addition in water, the gas, the restriction of equipment mixing diffuser efficiency in addition, actual material ratio should be than the theoretical value height.But too high meeting sharply descends the pH value, and inhibited reaction carries out and causes final outflow water acidity to increase, and increases the complicacy of subsequent disposal.For this reason, at pH=9, under the catalyst levels 50mg/L condition, investigated material ratio influence to treatment effect in 2.46～11 scopes.Result (Fig. 2) illustrates that except that the increase of cyanogen effect with material ratio improves, but after material ratio was 5, effect did not have obvious change, descends on the contrary to 7 later effects.This angle from chemical equilibrium is easy to obtain explain.Prove that thus material ratio truly has a certain best codomain, be 4.5～7th, suit.

Embodiment 2 different pH values are to removing the influence of cyanogen effect.Enter the waste water of one-level tower, its pH value usually between 10.1～11.5, CN ^-Be oxidized to CNO ^-And the further (NH that generates ₄) ₂SO ₄With HCO ^- ₃In pH value of solution value decline process rapidly, carry out.When the pH value is too high, CNO ^-The acidic conditions that does not possess further reaction, its generation will be suppressed; If the pH value is too low, then the reaction of the first step just is difficult to carry out, and under acidic conditions, CN ^-Be easy to generate HCN and overflow from cat head.Therefore control the pH value and be CN ^-Complete oxidation condition is provided is important.Use Ca(OH respectively) for this reason ₂, NaOH carried out selecting test to optimal ph.

Lime is taken from the raw material of SINTERING PRODUCTION, and its CaO content is about 80%.At CuSO ₄Add-on and material ratio are certain, do not influence under the water outlet effect condition to test, and result (Fig. 3) illustrates that the pH value is best results in 8.52～9.5 scopes, can guarantee CN in the water outlet when promptly the pH value is 9 left and right sides ^-Content is lower than 1.5mg/L.

Regulate the pH value with NaOH, more serious to equipment, corrosive pipeline, the water outlet muddiness is turned blue, and expense is also higher.So suggestion adopts lime to regulate,, be not difficult to handle though a small amount of sediment is arranged.

The influence of embodiment 3 catalyst levelss, test are that 96% industrial sulphuric acid copper is made catalyzer with purity.Water outlet, tail gas to system under its different amounts carry out integrated survey, condition is pH=8～10, raw water flow 400L/h, 60 ℃ of flue-gas temperatures, the result shows that (whole draining contains CN to obtain comparatively ideal, stable comprehensive treatment effect when adopting the 50mg/L catalyzer ^-1.38mg/L tail gas contains CN ^-16.8mg/m ³).When catalyst levels is 20mg/L, water outlet CN ^-Removal effect, but CN in the one-level tower tail gas ^-Content is higher; When consumption was 300mg/L, though effect is fine, expense was higher.Combining environmental allows emission concentration to investigate, and will not recommend.

The influence of embodiment 4 carrier performances and specific liquid rate.The carrier performance of reaction tower and the specific liquid rate of water inlet are to reaction times and CN ^-With SO ₂, O ₂The flow conditions influence that mixes contact is very big.The filler of test reaction tower rolls with the composite wave card and forms, and spray equipment is the porous water distributor.The internal resistance of actual measurement I and II tower is decreased and is respectively 0.137,0.147KPa(14,15 millimeter water column).When the filler virtual height is 4m, material ratio is 4.08～5.36, and the relation of specific liquid rate and treatment effect during catalyst levels 50mg/L, is measured in pH=8.5～9.5.The result shows that specific liquid rate is 5m ³/ hm ²During the left and right sides, more satisfactory (the whole draining CN of treatment effect ^-Content is to contain CN in 1.38mg/L, the I and II tower tail gas ^-Amount is respectively 79.60,16.8mg/m ³), the corresponding I and II tower internal reaction time respectively is 3～6 minutes.If adopt other filler, the definite of specific liquid rate and tower height should guarantee to be not less than the above-mentioned reaction times.

Embodiment 5 Temperature Influence.According to the chemical kinetics principle, temperature raises can improve speed of response.Owing to guaranteed the enough reaction times, Temperature Influence is not too obvious in laboratory test.On-the-spot pilot-plant test then is to carry out under extremely limited condition of equipment reaction time, improves temperature of reaction and just seems extremely important.The test explanation, temperature of reaction suitable in the tower is more than 40 ℃.Because sintering SO ₂Useless flue-gas temperature is generally at 80～110 ℃, temperature when entering reaction tower can make former water temp raise in the one-level tower about 30 ℃ about 60 ℃, raises about 20 ℃ in the secondary tower, therefore need not to establish in addition heat riser, and speed of response can be increased with exponential form.

The test of embodiment 6 technology stabilities.As a perfect treatment system, not only show as effectively, efficient height, but also will certain adaptive faculty be arranged to the random fluctuation of operational conditions promptly has certain stability.Test (the results are shown in Figure 4) illustrates that system truly has certain surge capability for the fluctuation of flue gas concentration, and the water quality situation after the processing is stable.This is because 1. in the flow process, waste water be with series system successively by reaction towers at different levels, flue gas then with parallel way enter respectively reaction towers at different levels and with the waste water counter current contact; 2. the reaction tower filler has certain specific surface area and porosity, thereby has aggravated gas, the liquid back-mixing degree in tower; 3. the volume of each conditioning equipment designed by 20 minute residence time, thereby had satisfied the stability requirement of system.

Be not difficult to find out from above-mentioned technical solution and embodiment, the single in the past treatment process that the present invention compares, its advantage and positively effect are significantly, have at least:

1. the treatment of wastes with processes of wastes against one another turns harm into good, and kills two birds with one stone.Same technological process can be administered simultaneously and be contained SO ₂Useless flue gas and cyanide wastewater;

2. save prior art and needed the special whole SO that prepare ₂, sulphite, O ₂Etc. main agents, need not the air blast device;

3. utilize the temperature of harmful smoke, improved the temperature of reaction of system effectively, thereby quickened reaction process, shortened the reaction times (for prior art 1/4～1/3);

4. technology is simple, and treatment effect is good, obvious environment benefit;

5. especially processing cost is extremely low, has very remarkable economic efficiency.One ton of high-cyanogen waste water of every improvement can be administered 2500～3000m simultaneously ³SO ₂Useless flue gas it is calculated that required expense only is 0.182 yuan, and this is minimum up to now processing cost.

6. be manufacturing enterprises such as iron and steel enterprise, particularly the ferromanganese industrial combination is administered blast furnace gas washing high cyanide containing wastewater and sintering SO ₂Flue gas has been opened up new way, has broad application prospects.

Claims (4)

1, high cyanide containing wastewater and contain the comprehensive processing method of the useless flue gas of sulfurous gas is made catalyzer with copper sulfate, regulates the pH value with basic solution, it is characterized in that making the useless flue gas that contains sulfurous gas to contact with cyanide wastewater.

2, according to the said method of claim 1, the alkali lye that it is characterized in that regulating pH value usefulness is aqua calcis.

3, according to the said method of claim 1, it is characterized in that containing the useless flue gas of sulfurous gas and the contact reacts of cyanide wastewater is carried out in the filler reaction tower, the reaction times of each single tower, temperature of reaction was more than 40 ℃ greater than three minutes.

4,, it is characterized in that material ratio is SO according to the said method of claim 1～3 ₂: CN ^-=4.57～7, the copper sulfate consumption is 50mg/L, and the optimum range of pH value is 8.5～9.5.

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