CN100443412C - Method for treating tail gas and waste water from rare earth finished ore acid method burning process - Google Patents

Method for treating tail gas and waste water from rare earth finished ore acid method burning process Download PDF

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CN100443412C
CN100443412C CNB2006100056958A CN200610005695A CN100443412C CN 100443412 C CN100443412 C CN 100443412C CN B2006100056958 A CNB2006100056958 A CN B2006100056958A CN 200610005695 A CN200610005695 A CN 200610005695A CN 100443412 C CN100443412 C CN 100443412C
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tail gas
spray
water
rare earth
hour
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CN1807253A (en
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郑巨根
邹宁
朴钟殷
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朴钟殷
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Abstract

The present invention relates to a method for treating tail gas and waste water from rare earth ore concentrate acid method calcining process, which belongs to the technical field of the environmental protection. The present invention is characterized in that (1) coal gas is used as fuel to calcine rare earth ore concentrate, and which is favorable for controlling calcining process parameters and recovering tail gas; (2) calcining ore immersion uses a cold immersing process, rare earth concentration in water immersion solution and the washing of rare earth carbonate are improved, and water consumption is greatly reduced; (3) ammonium bicarbonate is replaced by sodium bicarbonate to precipitate the rare earth carbonate, and the generation of ammonia nitrogen waste water is eliminated; (4) the tail gas of a calcining stove use a venturi tube for cooling and removing acid mist, three-stage spray is used for absorbing the tail gas; acid waste water hermetically circulates, treating processes, such as a lead electric demister, etc., are used for carrying out comprehensive treatment, and meanwhile, recovered sulphuric acid is used for calcining. The present invention can thoroughly treat the enterprise serious tail gas and the waste water which seriously pollute the environment, the discharge can reach standards, the energy is saved, the scarce water resource is particularly saved, and an enterprises becomes a clean, circulating and environmental protection enterprise.

Description

Acid system roasting rare earth concentrate process tail gas and method for treating wastewater

One, technical field

The present invention relates to a kind of acid system roasting rare earth concentrate process tail gas and method for treating wastewater, belong to the industry environmental protection technical field.

Two, prior art:

Handle Baotou rare earth ore concentrate the kinds of processes method is arranged.At present, domestic main employing high-temperature concentrated sulfuric acid method art breading Baotou rare earth ore concentrate.Roasted ore after the roasting transfers carbonated rare earth to through the water logging removal of impurities.Sulfuric acid and rare earth ore concentrate are mixed into roasting kiln, and the moisture content under hot conditions in the sulfuric acid is in time evaporated the formation acid mist, along with the reaction of material, produce a large amount of HF, SO 2, SO 3, SiF 4Deng gas.These gases are incorporated into and form tail gas in the flue gas together.

In producing the carbonated rare earth process,, produce a large amount of mother liquor of precipitation of ammonium that contains ammonia nitrogen and washes and treating tail gas water spray and absorb the acid waste water that produces because employing bicarbonate of ammonia is precipitation agent.

Existing rare earth enterprise administers tail gas though reclaim nitration mixture technology through three grades of water sprays, owing to have a large amount of HF, SO in the tail gas 2, SO 3Gas, spray absorbs difficulty and weak effect, and harmful gas concentration is still higher, does not reach discharging standards.On waste water treatment, adopt methods such as lime neutralization and electric osmose folding, but objectionable impurities is above standard still in the waste water, also is not reach emission request.

Because tail gas and waste water are not up to standard, and environment has been caused severe contamination, have influenced the healthy of the ecotope and the people.Simultaneously, also restrict the existence and the sustainable development of rare earth enterprise, limited the process that resources advantage transfers economic advantages to.

Three, summary of the invention:

The objective of the invention is to realize that treating tail gas reaches discharging standards, roasting tail gas produces acid waste water sealing and circulating, non-wastewater discharge; Improve the washing methods of water logging technology and carbonated rare earth, reduce water consumption and wastewater discharge significantly; The sulfuric acid that reclaims returns in the calcining process and uses, and accomplishes cleaning, circulation, energy-conservation.

The objective of the invention is to take following technical measures to realize:

Processing step is as follows:

(1) with rare earth ore concentrate and the vitriol oil by weight 1: the mixed of 1.3--1.6, send into the revolution roasting kiln, at 600--950 ℃ of roasting temperature 2--3 hour;

(2) the kiln discharge temperature is 450--550 ℃ a roasted ore, is cooled to 50--80 ℃ through the rotation drum type water cooler through the water spray, and be 1--1.5 hour cooling time;

(3) cooled roasted ore by solid-to-liquid ratio 1: 5--7, stirs at normal temperatures and carried out water logging in 4 hours, adds in the magnesium oxide afterwards and removal of impurities, and the pH value is controlled at 4--4.2, carries out Plate Filtration then;

(4) filtrate that Jin Chus is pressed total amount of rare earth adding 1: the carbonate of 1.45--1.55 is 30--45 ℃ in temperature, stirs to precipitate under the condition in 1--3 hour; Plate Filtration then, carbonated rare earth solid-to-liquid ratio 1: 5.5--6 stir washing once more in 0.5 hour in washing tank, dry with whizzer at last and obtain qualified carbonated rare earth product, and carbonate is a kind of in sodium bicarbonate, yellow soda ash or the bicarbonate of ammonia;

(5) the water logging slag behind the middle Plate Filtration of step (3) stirs to wash in 0.5--1 hour in washing tank by solid-to-liquid ratio 1: 5--7 and carries out Plate Filtration afterwards, and filtrate returning is used for step (3) water logging;

(6) tail gas discharged enters the Venturi meter water cooler in the roasting kiln,

Enter exhaust temperature 200--300 ℃;

50--80 ℃ of outlet exhaust temperature;

Tail gas flow velocity 40--60m/ second;

Water consumption 5-22m 3/ hour;

(7) the spray liquid that comes out from the Venturi meter water cooler enters the 1st interchanger, and the sour water temperature out after the 1st interchanger cooling is controlled at<and 40 ℃, enter the 1st pump pond through settling tank, return water cooler again and use; Sulfuric acid in the 1st pump pond reaches 30--65%, and delivering to vaporizer is 2.5--4.5Kg/cm at vapor pressure 2Evaporate reclaim(ed) sulfuric acid under the condition, discharge and return the secondary spray column after the fluorinated water steam cools off, reclaim(ed) sulfuric acid concentration is 70%-90%, replenishes after the new sulfuric acid of 92.5%-98%, returns roasting and uses;

(8) tail gas discharged enters the one-level spray column in the Venturi meter water cooler:

50--80 ℃ of import exhaust temperature;

The spray soak time is 10--20 second;

The spray water consumption is 30-50m 3/ hour;

Spray sour water temperature out is controlled at 40--50 ℃;

From the sour water that the one-level spray column comes out, enter the 2nd interchanger cooling after, the 2nd interchanger sour water temperature out is controlled at<40 ℃, returns the one-level spray column through the 2nd pump pond again and uses;

(9) one-level spray column tail gas discharged enters the secondary spray column:

The spray soak time is 3--5 second

The spray water consumption is 15--25m 3/ hour

Spray sour water temperature out is 35--45 ℃

From the sour water that the secondary spray column comes out, enter the 3rd interchanger cooling after, the 3rd interchanger sour water temperature out is controlled at<40 ℃, returns the secondary spray column through the 3rd pump pond again and uses the 1st pump pond, the 2nd pump pond and the 3rd pump pond parallel connection;

(10) secondary spray column tail gas discharged enters three grades of spray columns:

The spray soak time is 10--15 second;

Spray water consumption 30--50m 3/ hour;

From the sour water that three grades of spray columns come out, solid-to-liquid ratio 1: 2 adds lime, stirs at normal temperatures one hour, and adjust pH is to 5-9, the neutralization precipitation fluorochemical, and alkaline filtrate returns three grades of spray columns, filter residues and discards after filtering;

(11) three grades of spray column tail gas discharged enter plumbous electrostatic precipitator:

The tail gas flow velocity is 0.5--0.75m/ second;

Soak time is 10--15 second;

(12) tail gas discharged is up to state standards in the plumbous electrostatic precipitator, discharges.

Roasting kiln carries out roasting with coal gas.

The invention effect:

(1) coal-fired roasting changes into coal gas and carries out roasting.Its advantage is to burn gas to improve 30% than its heat energy utilization rate of direct burning coal, but save energy; Help the sinter process parameter control, to improve the rate of decomposition and the roasted ore quality product of roasted ore; Purify roasting tail gas, reduce pollutent in the baking flue gas, the recovery of the tail gas that is highly advantageous to is administered.

(2) before tail gas enters water spray absorption operation, be introduced into the Venturi meter water cooler.These technical measures make tail gas cooling, dedusting, also absorb most of acid mist, improve acid concentration.This operation one can alleviate the load of spray column, with the efficient of the absorption acid mist that improves spray column, two can reduce exhaust temperature, the reduction of exhaust temperature, further improved the assimilated efficiency of spray column, effect greatly improves the assimilated efficiency of spray column in the time of two factors.

(3) three grades of spray columns spray with alkali lye, and the further effect that absorbs acid mist that improves makes to enter acid mist content reduction again in the preceding tail gas of emptying chimney.

(4) through three grades of spray column tail gas discharged, acid mist content is very low, but directly discharging also might cause slight pollution to atmosphere.For before discharging, thoroughly eliminate acid mist, before the discharging atmosphere, increase plumbous electrostatic precipitator again, thoroughly eliminate acid mist.

After roasting tail gas taked abovementioned technology, make discharge tail gas meet " industrial furnace emission standard " fully, sulfuric acid mist also satisfies " discharge standard of air pollutants ".

(5) rising owing to the solubility with temperature of sulfuric acid rare earth in the aqueous solution reduces, thereby adopts cold soaking technology, improves the rare earth concentration of the aqueous solution.30g/L in the time of can be by hot dipping brings up to 60g/L.The infusion rare earth concentration is doubled, and not single production efficiency doubles, and also makes water consumption and wastewater flow rate reduce half.

(6) precipitation agent of precipitation carbonated rare earth is used sodium bicarbonate instead by orthocarbonic acid hydrogen ammonium, eliminates ammonia nitrogen sewage fully.Simultaneously, the improvement of carbonated rare earth washing process can make washes by former 7.5m 3/ T product is reduced to 2.5m 3/ T product.Saved a large amount of water consumptions equally.

(7) roasting tail gas water spray absorbs the acid waste water that produces, and also takes repeatedly to draw repeatedly technology, to improve the acidity of acid waste water, send vaporizer to remove after sulfuric acid and the hydrofluoric acid, and spray liquid returns and uses.Accomplish the sealing and circulating of roasting tail gas acid waste water, non-wastewater discharge.

(8) adopt interchanger, play the effect that reduces acid waste water and exhaust temperature, improve the efficient that spray absorbs.Simultaneously, the water coolant of interchanger recycles after the cooling tower cooling.

The waste water of (9) three grades of spray columns wherein fluorochemical of calcium oxide neutralization precipitation goes out mud through Plate Filtration, and filtrate is returned three grades of spray columns circulations and absorbed.

(10) sulfur waste acid and hydrofluoric acid in the Venturi meter water cooler are delivered to vaporizer through the concentration and evaporation reclaim(ed) sulfuric acid, and the sulfuric acid concentration of recovery is about 70%-90%, replenish after a certain amount of new sulfuric acid, can return roasting and use.

The present invention has fundamentally solved tail gas and contaminated wastewater environmental problem that acid system roasting rare earth concentrate technology produces.Roasting tail gas is taked Venturi meter cooling demist, and three grades of sprays absorb, technical measures such as plumbous electrostatic precipitator, and detecting hydrogen fluoride through environmental administration is 0.785mg/m 3, sulfuric acid mist is 22.59mg/m 3, SO 2Be 24.87mg/m 3, flue dust is 1.24mg/m 3, reach emission standard fully.

Waste water treatment adopts cold soaking technology, uses precipitation agent instead, improves after the washing process of carbonated rare earth, and efflux technology waste water is controlled at: the outer discharge capacity 10m of waste water 3-12m 3/ T product between the pH6-8, below the ammonia nitrogen 10mg/L, below the fluorine 1mg/L, has thoroughly changed pH value, ammonia nitrogen and fluorine present situation not up to standard in the efflux wastewater.Simultaneously, compare, can accomplish to reduce wastewater discharge more than 70% with similar enterprise.

Adopt the present invention, not only make the tail gas and the waste water of enterprise's serious environment pollution of acid roasting rare earth concentrate, be solved through administering, and saved the energy, water resources especially more in short supply makes enterprise become cleaning, circulation, environment-friendly type enterprise.

Four, description of drawings:

Accompanying drawing 1 is process flow diagram of the present invention.

Accompanying drawing 2 reclaims the exhaust gas flow path synoptic diagram for the present invention.

Five, embodiment

Embodiment 1: enter roasting kiln after the mixed of rare earth ore concentrate and sulfuric acid 1: 1.3--1.6 and carried out roasting 2-3 hour under 600 ℃ of-950 ℃ of temperature with coal gas.Roasted ore kiln discharge temperature after the roasting is 450-550 ℃, sprays through the rotation drum type water cooler to be cooled to 50-80 ℃ and to enter the cold soaking operation, and the rare earth concentration of infusion is at 60-70g/L.The sulfuric acid rare earth infusion is in magnesium oxide and removal of impurities, and the pH value is controlled at 4--4.2, filters with sheet frame.Water logging slag after filtering stirs in washing tank by solid-to-liquid ratio 1: 5--7 and washed in 0.5--1 hour, and the filtrate after the Plate Filtration is returned the cold soaking operation and used.Leach liquor is pressed total amount of rare earth and added 1: the 1.45--1.55 sodium bicarbonate is 30--45 ℃ in temperature, stirs to precipitate under the condition in 1--3 hour; Plate Filtration then, carbonated rare earth solid-to-liquid ratio 1: 5.5--6 stir washing once more in 0.5 hour in washing tank, dry with whizzer at last and obtain qualified carbonated rare earth product.

Owing to adopt cold soaking technology, make infusion middle-weight rare earths concentration bring up to 60-70g/L by about 30g/L, can make mother liquor of precipitation of ammonium by former 15m 3/ T product is reduced to 7.5m 3/ T product, the improvement of carbonated rare earth washing process can make washing water by former 7.5m 3/ T reduces to 2.5m 3/ T, two totals can be by former 22.5m 3/ T reduces to 10m 3/ T.

Use the sodium bicarbonate depositing technology instead by past employing ammonium bicarbonate precipitation carbonated rare earth, got rid of ammonia nitrogen sewage fully.

The exhaust temperature that the roasting kiln afterbody is discharged is generally between 200 ℃-300 ℃, tail gas makes exhaust temperature reduce to 50 ℃-80 ℃ through the Venturi meter water cooler, remove most of particulate matter in the tail gas, and draw most of acid mist, absorb hydrogen fluoride and sulfuric acid mist in the tail gas through secondary filler water spray column again, liquid draw recycles after cooling off by interchanger, and to improve the concentration of acid in the absorption liquid, 99% sulfuric acid mist and hydrogen fluoride are absorbed in the tail gas.Three grades of spray columns adopt alkaline water to absorb, and remove 70% above SO in the tail gas 2With pollutents such as the hydrogen fluoride of remnants and sulfuric acid mists.Three grades of spray column outlet tail gas are further removed sulfuric acid mist, fluorochemical and the flue dust that purifies in the tail gas of back through plumbous electrostatic precipitator again, finally enter atmosphere by a 60m chimney stack.Take after the above measure, sulfuric acid mist is 22.57mg/m in institute's emission gases 3, fluorochemical is 0.785mg/m 3, flue dust is 1.24mg/m 3, SO 2Be 24.87mg/m 3, reached discharging standards.

Sulfuric acid and hydrofluoric acid nitration mixture and secondary spray column absorption liquid that the Venturi meter water cooler absorbs, process concentration and evaporation recovery concentration is 70% sulfuric acid, returns roasting and uses.

Three grades of spray columns outlet absorption liquids, through lime neutralization precipitation fluorochemical, after filtration after, alkaline filtrate returns three grades of spray columns, filter residue discards.

Three grades of spray column spray waters are repeatedly recycled, and have not only improved the concentration of acid in the absorption liquid, and the sealing and circulating of having accomplished roasting tail gas acid waste water, non-wastewater discharge.

Claims (2)

1, acid system roasting rare earth concentrate process tail gas and method for treating wastewater is characterized in that: adopt following process steps:
(1) with rare earth ore concentrate and the vitriol oil by weight 1: the mixed of 1.3--1.6, send into the revolution roasting kiln, at 600--950 ℃ of roasting temperature 2--3 hour;
(2) the kiln discharge temperature is 450--550 ℃ a roasted ore, is cooled to 50--80 ℃ through the rotation drum type water cooler through the water spray, and be 1--1.5 hour cooling time;
(3) cooled roasted ore by solid-to-liquid ratio 1: 5--7, stirs at normal temperatures and carried out water logging in 4 hours, adds in the magnesium oxide afterwards and removal of impurities, and the pH value is controlled at 4--4.2, carries out Plate Filtration then;
(4) filtrate that Jin Chus is pressed total amount of rare earth adding 1: the carbonate of 1.45--1.55 is 30--45 ℃ in temperature, stirs to precipitate under the condition in 1--3 hour; Plate Filtration then, carbonated rare earth solid-to-liquid ratio 1: 5.5--6 stir washing once more in 0.5 hour in washing tank, dry with whizzer at last and obtain qualified carbonated rare earth product, and carbonate is a kind of in sodium bicarbonate, yellow soda ash or the bicarbonate of ammonia;
(5) the water logging slag behind the middle Plate Filtration of step (3) stirs to wash in 0.5--1 hour in washing tank by solid-to-liquid ratio 1: 5--7 and carries out Plate Filtration afterwards, and filtrate returning is used for step (3) water logging;
(6) tail gas discharged enters the Venturi meter water cooler in the roasting kiln,
Enter exhaust temperature 200--300 ℃;
50--80 ℃ of outlet exhaust temperature;
Tail gas flow velocity 40--60m/ second;
Water consumption 5-22m 3/ hour;
(7) the spray liquid that comes out from the Venturi meter water cooler enters the 1st interchanger, and the sour water temperature out after the 1st interchanger cooling is controlled at<and 40 ℃, enter the 1st pump pond through settling tank, return water cooler again and use; Sulfuric acid in the 1st pump pond reaches 30--65%, and delivering to vaporizer is 2.5--4.5Kg/cm at vapor pressure 2Evaporate reclaim(ed) sulfuric acid under the condition, discharge and return the secondary spray column after the fluorinated water steam cools off, reclaim(ed) sulfuric acid concentration is 70%-90%, replenishes after the new sulfuric acid of 92.5%-98%, returns roasting and uses;
(8) tail gas discharged enters the one-level spray column in the Venturi meter water cooler:
50--80 ℃ of import exhaust temperature;
The spray soak time is 10--20 second;
The spray water consumption is 30-50m 3/ hour;
Spray sour water temperature out is controlled at 40--50 ℃;
From the sour water that the one-level spray column comes out, enter the 2nd interchanger cooling after, the 2nd interchanger sour water temperature out is controlled at<40 ℃, returns the one-level spray column through the 2nd pump pond again and uses;
(9) one-level spray column tail gas discharged enters the secondary spray column:
The spray soak time is 3--5 second
The spray water consumption is 15--25m 3/ hour
Spray sour water temperature out is 35--45 ℃
From the sour water that the secondary spray column comes out, enter the 3rd interchanger cooling after, the 3rd interchanger sour water temperature out is controlled at<40 ℃, returns the secondary spray column through the 3rd pump pond again and uses the 1st pump pond, the 2nd pump pond and the 3rd pump pond parallel connection;
(10) secondary spray column tail gas discharged enters three grades of spray columns:
The spray soak time is 10--15 second;
Spray water consumption 30--50m 3/ hour;
From the sour water that three grades of spray columns come out, solid-to-liquid ratio 1: 2 adds lime, stirs at normal temperatures one hour, and adjust pH is to 5-9, the neutralization precipitation fluorochemical, and alkaline filtrate returns three grades of spray columns, filter residues and discards after filtering;
(11) three grades of spray column tail gas discharged enter plumbous electrostatic precipitator:
The tail gas flow velocity is 0.5--0.75m/ second;
Soak time is 10--15 second;
(12) tail gas discharged is up to state standards in the plumbous electrostatic precipitator, discharges.
2, acid system roasting rare earth concentrate process tail gas according to claim 1 and method for treating wastewater, it is characterized in that: roasting kiln carries out roasting with coal gas.
CNB2006100056958A 2006-01-18 2006-01-18 Method for treating tail gas and waste water from rare earth finished ore acid method burning process CN100443412C (en)

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CN102489034B (en) * 2011-11-16 2014-02-26 中冶东方工程技术有限公司 Respective recovery method for rare earth concentrate multi-stage baking tail gases, and device thereof
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CN104208993A (en) * 2014-07-31 2014-12-17 仙桃市中星电子材料有限公司 Device and method for treatment of calcination tail gas
CN106119522B (en) * 2016-07-21 2019-06-18 中国恩菲工程技术有限公司 The extracting method of Rare Earth Mine
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CN106145443A (en) * 2016-07-29 2016-11-23 乐山东承新材料有限公司 A kind of processing method of Rare Earth Production waste water
CN107164629A (en) * 2017-04-25 2017-09-15 昆明理工大学 A kind of aluminium scrap base hydrogenation catalyst processing method based on microwave oxygen-enriched air roasting

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