CN101264904A - Method for producing sodium bicarbonate and sulfur from mirabilite by wet process - Google Patents

Abstract

The invention discloses a method for clean method for producing sodium bicarbonate and sulphur by means of Glauber salt wet method for reducing the emission of CO2 and avoiding the discharge of wastewater, which comprises the following steps: A, sodium sulphide preparing process, B, hot carbonatation process, C, sulphur preparing process, D, cold carbonization process, and E, mother liquor purifying. Glauber salt coal is reduced and calcined into sodium sulphide, and the sodium sulphide solution is heated and carbonized into a mixed solution with the soda as the main component by use of sodium bicarbonate, then the mixed solution is cold-carbonated by CO2 to separate out NaHCO3 crystal, which is dried to finally obtain the soda in conformity with relevant standard. The production method has the advantages of simple process, environmental friendliness, no pollution, full circulation of the mother liquor, and no wastewater discharged.

Description

The method of heavy alkali of saltcake wet production and sulphur

Technical field

The present invention relates to saltcake or containing the chromium saltcake is raw material, the method for heavy alkali of coproduction and sulphur.

Background technology

Now the production method of heavy alkali adopts salt to be raw material Wei Ersuo system alkaline process or Hou Shi system alkaline process or urao direct production method mostly.The employing saltcake is that the method for the heavy alkali of raw material production has leblanc process in early days, and the improvement leblanc process of the diligent applied chemistry of USSR (Union of Soviet Socialist Republics) row word lattice institute establishment.

All there is the energy consumption height in the method for early stage saltcake system alkali, and the shortcoming of waste discharge and waste gas does not see so far that in China aforesaid method is by industrial employing.

China's saltcake reserves are very abundant, along with the minimizing gradually of salt resource, do not had the price advantage with respect to mirabilite resource, and the technical study of the heavy alkali of saltcake production has highlighted its importance.

Common heating and calcining reaction direct production soda ash of saltcake and Wingdale and by-product sulphur, the direct method of lime and the indirect method of employing ammonification and carbonization have been mentioned in CN1390786 sodium sulfate (saltcake, Sodium sulfate anhydrous.min(99)) the production standard soda ash way.Its direct method has added Wingdale in batching, one increases raw material, causes new slag, two CO that come decomposition of limestone to produce ₂Gas can not be reduced to soda ash with saltcake, CO gas only, but impossible.Even if moreover reaction, can not carry out thoroughly to a direction as chemical reaction, therefore, generation saturated soaks and drench liquid is the mixed solution of sodium sulfate, soda ash and calcium hydroxide, the employing cold method can not be isolated pure soda ash, whole technology does not have the industrialization meaning.Also have, sulphur and lime mixture adopt digestion process, and the rate of recovery of its sulphur can't guarantee that quality also can't guarantee.

One kind of CN1490247 is that raw material produces that to adopt sodium dichromate 99 in the novel method of soda ash be oxygenant with the saltcake, saltcake and Wingdale reaction, progressively be converted into sulfate precipitation, sodium dichromate 99 is reduced to Sodium chromate, the Sodium chromate carbonating is converted into sodium dichromate 99 and heavy alkali again.Earlier do not consider whether saltcake can carry out with the process of Wingdale reaction precipitation sulfate radical, because of yellow ultramarine solubleness lower.Only the chromic salt carbonating is converted into the process of sodium dichromate 99 and heavy alkali, and its expense is higher, the condition harshness.In the existing chromic salts industry in the high value chromic salts products production, the Sodium chromate carbonating is converted into also industrializing implementation not of sodium dichromate 99, and is existing at the experimental stage, is used for the main heavy alkali of producing still more.Moreover well-known, chromium is a kind of toxic substance, and yellow ultramarine is generally acknowledged especially controls the cancer thing, and as the heavy alkali of medium production, not only process increases danger, and will be with a spot of hazardous material in the product with it, and the purposes of product can be restricted.

Summary of the invention

The object of the invention provides a kind of realization and reduces discharging CO ₂, the heavy alkali of saltcake wet cleaning production of non-wastewater discharge and the method for sulphur.

The present invention includes the following step:

A, Sodium Sulphide preparation section: principal reaction principle Na ₂SO ₄+ 2C=Na ₂S+2CO ₂

Saltcake and coal are with 100: 20～24 ratio homogenizing mixings, and 1050 ℃～1080 ℃ calcinings of high temperature section 30 minutes～60 minutes, calciner was selected from reverberatory furnace or rotary kiln, replaces with retort furnace in the laboratory, sinters Na into ₂The S clinker is with the Na that obtains 250g/l～300g/l after heavy alkali liquor that returns and the water logging pouring ₂The S clear liquid; The CO that roasting process produces ₂Gas concentration is 16～33%, CO ₂After the washing of gas process, the desulfurization, be used for the cold carbonization of alkali producing process;

B, hot carbonating operation: principal reaction principle Na ₂S+NaHCO ₃=2Na ₂CO ₃+ H ₂S ↑

At first at Na ₂Add the mother liquor after separation weighs alkali in the S clear liquid, it is Na that the adding mother liquor contains heavy alkali number ₂1.35 times of S mass fraction boil under 100～105 ℃ of boiling conditions and endure 3～6 hours, Na ₂S and heavy alkali NaHCO ₃Reaction makes H ₂S gas fully discharges, residual Na in the solution ₂S is 2.5～3.2g/l, Na in the solution ₂CO ₃Content should be controlled at 200g/l～210g/l, the H of release ₂The S gas concentration reaches 90%～95%, and employing Kraus process production purity is 95～98% sulphur; Secondly, the solution that boils after enduring is cooled to 60～70 ℃ naturally, filtered while hot, and slag returns calcination process;

C, sulphur preparation section: production principle H ₂S+O ₂=2S+H ₂O

H ₂The S gas concentration is produced sulphur technology and must be adopted general Kraus process production 90～95%.1 ton of soda ash of every production produces H ₂S gas is raw material, can make sulphur 220～230kg.

Na ₂The S clear liquid is used roasting kiln tail tail gas clean-up and next CO ₂The gas carbonization, CO ₂Gas gas volume percentage concentration is 16～33%; It is 100%CO that 1 ton heavy alkali of every production consumes content ₂Gas 580kg, CO ₂The utilization ratio of gas is 50%; Carbonization temperature is controlled at 50～70 ℃, and drop temperature is controlled at 28～30 ℃ at the bottom of the tower;

D, cold carbonation process: by the hot carbonating operation of B step CO ₂The yellow soda ash Na that gas carbon heat-transmission reaction obtains ₂CO ₃Mixing solutions, because under the cold state, NaHCO ₃Solubleness is lower, with the reduction of temperature, progressively forms and separates out sodium bicarbonate NaHCO ₃The solution that the carbonization that crystal, Jiang Tadi are emitted is good filters, and with 30 ℃ of warm water washings, obtains meeting the heavy alkali product of GB with 50 ℃ of temperature oven dry.

Main carburizing reagent principle Na ₂CO ₃+ CO ₂+ H ₂O=2NaHCO ₃

CO ₂The gas consumption amount is calculated

This process CO ₂Specific absorption only has 50%, the theoretical 100%CO that needs ₂Gas 415kg, actual needs CO ₂900kg, weight alkali calcining can reclaim CO ₂400kg, the rate of recovery 96%.Not enough CO ₂All derive from Sodium Sulphide and produce calcination process.

1t 60% Na ₂With the feed coal 450kg of fixed carbon 60%, also add coal combustion 550kg simultaneously in the actual production of S product, just add up to the coal total amount at 1000kg.

Coal consumption rate is considered by 90%, is produced 100% CO ₂1980kg can satisfy the required 100%CO of carbonization fully ₂500kg.By calculating the CO that the Sodium Sulphide production process produces ₂Gas volume can satisfy the needs of producing soda ash fully, and no longer newly-increased limestone kiln produces CO ₂Gas.

CO under the normal conditions ₂Air tightness is 1.977kg/m ³, every system 1t soda ash needs 100% CO ₂900kg, signature shape gas 455m ³After the calcining kiln tail gas clean-up is collected, homogenizing CO ₂Gas concentration is 22%, therefore, roll over for actual concentrations mark shape gas be 2068m ³

E, mother liquor purification: the mother liquor 50% that the cold carbonation process of D step produces returns the A step and is used for Na ₂S soaks pouring, and 50% time the hot carbonating operation of B step is used for separate sulfur; Work as Na ₂Sulfothiorine Na in the S clear liquid ₂S ₂O ₃, S-WAT Na ₂SO ₃, sodium sulfate Na ₂SO ₄When comprehensive content surpasses 100g/l, add barium sulphide BaS solution, be converted into the barium salt precipitation, separate with insoluble slag.

Because Recycling Mother Solution can cause the SO of system ₄ ^2-, SO ₃ ^2-, S ₂O ₃ ^2-Ion is rich long-pending, surpass 150g/l after, when separating out heavy alkali, can carry a large amount of vitriols simultaneously secretly, the heavy alkali content of influence.Moreover sulfate concentration increases, and can cause scale velocity quickening in the carbonating tower, reduces heat transfer efficiency, prolongs the crystallization of sodium bicarbonate time.Therefore, must purify just mother liquor and can guarantee recycle.The present invention adopts and adds the BaS additive method, makes vitriol in the mother liquor with the form precipitate and separate of barium sulfate, reaches the purpose of purification.

Reaction principle

BaS+S ₂O ₃ ^2-＝S ^2-+BaS ₂O ₃↓

BaS+SO ₃ ^2-＝S ^2-+BaSO ₃↓

BaS+SO ₄ ^2-＝S ^2-+BaSO ₄↓

By the mother liquor purification operation, can realize mother liquor 100% recycle, realize wastewater zero discharge.

The present invention separates heavy alkali of system and sulphur from saltcake, can not only solve the production technology bottleneck of heavy alkali, and the sulphur of coproduction can remedy the passive situation of the basic dependence on import of China's sulfuric acid industry raw material, prevents that domestic sulfuric acid price from being prepared enterprise by external sulphur and handling.

The invention provides a kind of saltcake is the novel process that raw material is produced heavy alkali and sulphur, has realized reduction of discharging CO ₂, non-wastewater discharge clean production.

The principal feature of this invention is

1, decompose saltcake reductive agent coal, cheapness also is easy to get.

2, adopt heavy alkali liquor carbonization Na ₂S solution is converted into NaCO ₃, discharge H ₂S gas has been realized separating of Na and S element.

3, the cold carbonating of the soda ash solution alkali NaHCO that attaches most importance to ₃Used CO ₂The tail gas that gas produces for the Sodium Sulphide preparation process.The heavy alkali of every production 1t can realize reducing discharging CO ₂480kg.

4, by adding the BaS additive, generate the barium salt precipitation and purify mother liquor, realize mother liquor 100% recycle, non-wastewater discharge.

Compare with the existing technology of producing heavy alkali with saltcake, the present invention has following advantage:

1, technology is simple, and the present invention adopts the Sodium Sulphide production technique to improve, and can realize fast.

2, environmental protection: the every production of the present invention 1t is heavy, and alkali reduces discharging CO ₂480kg;

3, pollution-free: the present invention realizes that mother liquor circulates fully, no efflux wastewater;

4, can utilize the useless saltcake of industry, contain the chromium saltcake as the byproduct in the chromic salts technology.The chromium saltcake that contains of by-product contains solubility Cr in the chromic salts industry ⁶⁺About 0.2～0.5% (with Na ₂Cr ₂O ₇.H ₂The O meter), environment there is certain harm.Saltcake of the present invention and coal carry out high-temperature reaction process, can be with Cr ⁶⁺Be reduced to nontoxic Cr ₂O ₃(2Na ₂Cr ₂O ₇.H ₂O+C=2Cr ₂O ₃+ 2Na ₂CO ₃+ CO ₂+ H ₂O).Have the characteristics completely of detoxifying.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Embodiment

The following examples can make those skilled in the art more fully understand the present invention, but do not limit the present invention in any way.

Embodiment 1:

A, Sodium Sulphide preparation section: behind 100g thenardite and the 24g coal mixing, put into porcelain platinum, insert the inherent 1050 ℃ of calcinings of retort furnace 30 minutes, frit 56g, Na ₂S content is 65%, drenches for containing Na with the 480ml water logging behind the porphyrize ₂The solution of S75.8g/l.

B, hot carbonating operation: at first at Na ₂Add the heavy alkali of 95g in the S clear liquid, boiled the H of release 5 hours at 100 ℃ ₂The S gas concentration reaches 90%～95%, and employing Kraus process production purity is 95～98% sulphur; Secondly, the solution that boils after enduring is cooled to 60～70 ℃ naturally, filtered while hot, and slag returns calcination process;

C, sulphur preparation section: filtrate is used 22%CO ₂Gas carbonization under 0.35MPa pressure, carbonization temperature is controlled at 50～70 ℃, and drop temperature is controlled at 28～30 ℃ at the bottom of the tower;

The solution that the carbonization that D, cold carbonation process: Jiang Tadi emit is good filters, and with 30 ℃ of warm water washings, dries to such an extent that 113.7g weighs alkali, NaHCO with 50 ℃ of temperature ₃Content 98.3%

E, mother liquor purification: the mother liquor 50% that the cold carbonation process of D step produces returns the A step and is used for Na ₂S soaks pouring, and 50% time the hot carbonating operation of B step is used for separate sulfur; Work as Na ₂Sulfothiorine Na in the S clear liquid ₂S ₂O ₃, S-WAT Na ₂SO ₃, sodium sulfate Na ₂SO ₄When comprehensive content surpasses 100g/l, add barium sulphide BaS solution, be converted into the barium salt precipitation, separate with insoluble slag.

Embodiment 2: with embodiment 1, difference is as follows, and in the A step Sodium Sulphide preparation section: behind 100g thenardite and 20g coal mixing, calciner is a reverberatory furnace, and calcining temperature is adjusted into 1080 ℃, calcines clinker 55g, Na 60 minutes ₂S content is 64.5%, drenches for containing Na with the 480ml water logging behind the porphyrize ₂The solution of S73.80g/l.Add the heavy alkali of 95g, boil 6h at 105 ℃, impurity screening, filtrate is used 22%CO ₂Gas carbonization under 0.35MPa pressure is filtered 50 ℃ of filter cakes and is dried to such an extent that 106.3g weighs alkali, NaHCO ₃Content 98.5%.

Embodiment 3: with embodiment 2, difference is as follows, and in the A step Sodium Sulphide preparation section: behind 100g thenardite and 22g coal mixing, calciner is a rotary kiln, and calcining temperature is adjusted into 1065 ℃, calcines 45 minutes; Add the heavy alkali of 95g, boil 3h at 102 ℃, impurity screening, filtrate is used 22%CO ₂Gas carbonization under 0.35MPa pressure is filtered 50 ℃ of filter cakes and is dried to such an extent that 109.2g weighs alkali, NaHCO ₃Content 98.5%.

The experimental result of embodiment 1-3 sees the following form: the unit of mark is g/l

Data are known in the table, Na ₂Low and reaction times of S and heavy alkali reaction temperature in short-term, the Na that is not transformed in the solution ₂S content is higher, causes the Na in the mother liquor ₂S ₂O ₃Amount increases simultaneously; Na in the thermalization liquid ₂CO ₃When content surpassed 210g/l, heavy alkali content reduced, and certain mistake is low can to make heavy alkali carbonation rate descend, and experiment 2 is than 3, and output descends.

Claims (1)

1, the method for heavy alkali of a kind of saltcake wet production and sulphur is characterized in that it comprises the following steps:

A, Sodium Sulphide preparation section: saltcake and coal are with 100: 20～24 ratio homogenizing mixings, and 1050 ℃～1080 ℃ calcinings of high temperature section 30 minutes～60 minutes, calciner was selected from reverberatory furnace or rotary kiln, sinters Na into ₂The S clinker is with the Na that obtains 250g/l～300g/l after heavy alkali liquor that returns and the water logging pouring ₂The S clear liquid; The CO that roasting process produces ₂Gas concentration is 16～33%, CO ₂After the washing of gas process, the desulfurization, be used for the cold carbonization of alkali producing process;

B, hot carbonating operation: at first at Na ₂Add the mother liquor after separation weighs alkali in the S clear liquid, it is Na that the adding mother liquor contains heavy alkali number ₂1.35 times of S mass fraction boil under 100～105 ℃ of boiling conditions and endure 3～6 hours, Na ₂S and heavy alkali NaHCO ₃Reaction makes H ₂S gas fully discharges, residual Na in the solution ₂S is 2.5～3.2g/l, Na in the solution ₂CO ₃Content should be controlled at 200g/l～210g/l, the H of release ₂The S gas concentration reaches 90%～95%, and employing Kraus process production purity is 95～98% sulphur; Secondly, the solution that boils after enduring is cooled to 60～70 ℃ naturally, filtered while hot, and slag returns calcination process;

C, sulphur preparation section: Na ₂The S clear liquid is used roasting kiln tail tail gas clean-up and next CO ₂The gas carbonization, CO ₂Gas gas volume percentage concentration is 16～33%; It is 100%CO that 1 ton heavy alkali of every production consumes content ₂Gas 580kg, CO ₂The utilization ratio of gas is 50%; Carbonization temperature is controlled at 50～70 ℃, and drop temperature is controlled at 28～30 ℃ at the bottom of the tower;

The solution that the carbonization that D, cold carbonation process: Jiang Tadi emit is good filters, and with 30 ℃ of warm water washings, dries the alkali finished product of promptly attaching most importance to 50 ℃ of temperature;

E, mother liquor purification: the mother liquor 50% that the cold carbonation process of D step produces returns the A step and is used for Na ₂S soaks pouring, and 50% time the hot carbonating operation of B step is used for separate sulfur; Work as Na ₂Sulfothiorine Na in the S clear liquid ₂S ₂O ₃, S-WAT Na ₂SO ₃, sodium sulfate Na ₂SO ₄When comprehensive content surpasses 100g/l, add barium sulphide BaS solution, be converted into the barium salt precipitation, separate with insoluble slag.

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