CN1944291B

CN1944291B - Method for teating heavy alkali filter liquid in synthesizing alkali producing method

Info

Publication number: CN1944291B
Application number: CN2006100220524A
Authority: CN
Inventors: 王旭东; 高健; 王兆华; 黄竞
Original assignee: Honghe Chemical Industry Co Ltd Zigong
Current assignee: Honghe Chemical Industry Co Ltd Zigong
Priority date: 2006-10-17
Filing date: 2006-10-17
Publication date: 2010-12-29
Anticipated expiration: 2026-10-17
Also published as: CN1944291A

Abstract

The method of treating heavy alkali filtering liquid from alkali synthesizing production process includes evaporating ammonia to decompose NH4HCO3 and recover NH3 and CO2, adding MgO and evaporating ammonia to recover NH3, separating NaCl and returning to salt dissolving step, crystallizing magnesium chloride, hydrolyzing magnesium chloride to obtain MgO and HCl, reusing MgO while obtaining HCl. The present invention can raise the utilization rate of NaCl greatly, lower power consumption and cost.

Description

The treatment process of filtration of bicarbonate liquid in the synthetic system alkaline process

Technical field

The invention belongs to synthetic system alkali producing and manufacturing technique, particularly a kind of to filtration of bicarbonate mother liquor in its technical process decompose, isolating method, the ammonium chloride in the mother liquor can be decomposed ammonification (NH by this method ₃) and hydrogenchloride (HCl), isolate sodium-chlor (NaCl) simultaneously.NH ₃Return preceding operation as prepared using with NaCl, HCl uses it for anything else in addition as industrial chemicals.

Background technology

No matter produce in the process of soda ash at synthetic system alkaline process (comprising solvay soda process and connection alkaline process), be to adopt the mother liquor behind the filtration of bicarbonate that solvay soda process or connection alkaline process all need the carbonating operation is generated to handle; Contain multiple materials such as ammonium chloride, bicarbonate of ammonia, sodium-chlor, yellow soda ash, sodium bicarbonate and free ammonia in its mother liquor.Adopting the solvay soda process production technique is to add calcium oxide wherein ammonium chloride is carried out decomposition reaction, reclaims ammonia and return preceding operation (inhaling the ammonia operation) and utilize to the processing of this mother liquor, then with remaining raffinate (slag) as waste discharge; The defective one of this method is the utilization ratio less than 75% of sodium-chlor; The 2nd, give off contain the chlorination calcium wasting liquid in a large number and waste residue causes " public hazards ".The processing of connection alkaline process counterweight alkali filtrated stock then is to separate out ammonium chloride as byproduct, sodium-chlor and remaining mother liquid recycling by cold analysis and salt analysis method; Though this method has the sodium-chlor utilization ratio can be up to more than 90%, and waste liquid, waste residue are discharged advantages such as few, but a large amount of byproduct ammonium chloride as fertilizer sources is chloride because of it, bigger to the structure deteriorate of soil, life-time service will cause soil acidification and cause quality of agricultural product to descend, therefore the scope of application and consumption all are subjected to very big restriction, because a large amount of ammonium chloride overstocks, outlet is not smooth, become the burden that the connection alkaline process is produced soda ash, restricted the development that the connection alkaline process is produced soda ash greatly.At the problem of outlet of byproduct ammonium chloride, be 85108709 at application number, denomination of invention a kind ofly adopts ammonium chloride and contains magnesium material reacting by heating, decomposites the method for ammonia and hydrogenchloride for disclosing in the patent documentation of " novel method of decomposing ammonium chloride ".This method is because directly to adopt byproduct ammonium chloride be raw material, thereby can not be used for the mother liquor behind the filtration of bicarbonate is handled, and needs newly-increased independently treatment process and corresponding apparatus, and energy consumption height, suitability for industrialized production benefit low, disadvantage such as be difficult to apply.And be ZL92114069X in the patent No., denomination of invention is for further disclosing a kind of decomposing ammonium chloride to produce the method for ammonia and hydrogenchloride in the patent documentation of " decomposition process for ammonium chloride ".This method is reacted first magnesium oxide is added in the solution that is made into by a certain percentage by solid ammonium chloride, under 105～136 ℃ of temperature, react then ammonia and magnesium chloride solution, magnesium chloride solution is placed under 210～310 ℃ of temperature hydrolysis to emit hydrogenchloride and generate the hydroxyl magnesium chloride, the hydroxyl magnesium chloride continues hydrolysis and generates magnesium hydroxide again; After this then with the ammonium chloride solution reaction ammonium chloride is decomposed ammonification and hydrogenchloride, solve the problem of outlet of ammonium chloride with this by hydroxyl magnesium chloride or magnesium hydroxide circulation.Though this method can be decomposed ammonium chloride the industrial chemicals hydrogenchloride of ammonification and market demand, owing to be directly to handle equally, thereby still there be the energy consumption height, cannot incorporate the disadvantage in the connection alkali process flow process at ammonium chloride product; In addition, owing to adopting basic magnesium chloride to make recycle stock, its essence is by basic magnesium chloride and ammonium chloride and react that the efficient of its decomposing ammonium chloride is poor, the production cost height, has also limited the suitability for industrialized production prospect of this method greatly to decomposite ammonia.

Summary of the invention

The objective of the invention is to study a kind of treatment process that is used for synthetic system alkaline process filtration of bicarbonate liquid.So that the ammonium chloride in the filtered liquid is decomposed ammonification and hydrogenchloride and isolates sodium-chlor, sodium-chlor and ammonia return the molten operation of salt and inhale the ammonia operation as raw material respectively, hydrogenchloride overcomes waste liquid in the solvay soda process (slag) to the pollution of environment, the utilization ratio of raising sodium-chlor then as the industrial chemicals utilization thereby reach; Effectively solve byproduct ammonium chloride outlet difficulty in the production of connection alkaline process, seriously restrict the problem of soda ash production development; And cut down the consumption of energy and purposes such as benefit that production cost, raising soda ash are produced.

Solution of the present invention is at first filtration of bicarbonate liquid to be carried out pre-ammonia still process to handle, to decompose NH wherein ₄HCO ₃Deviate from CO ₂And NH ₃After, in debris, add MgO again and steam NH ₃Reaction, crystallization goes out NaCl and magnesium chloride respectively then, and last hydrolysis magnesium chloride gets HCl and MgO.Gained NaCl and NH ₃Return dissolved salt respectively and inhale the ammonia operation, the MgO recycle, HCl reclaims the back and uses as industrial chemicals.Thereby the inventive method comprises:

A, pre-ammonia still process: the filtration of bicarbonate liquid that will synthesize in the alkali-making process places in the pre-ammonia steaming device, does not have the pre-ammonia still process processing that refluxes under gauge pressure 0.1～1.0MPa and 100～180 ℃ of temperature, with NH wherein ₄HCO ₃Resolve into NH ₃, CO ₂And H ₂O, to the debris free NH ₃Content＜0.1mol/L ends; NH ₃, CO ₂Reclaim stand-by;

B, ammonia still process: in the debris after the A operation is handled by with NH wherein ₄1.1～1.3 of the required MgO weight of Cl complete reaction is extraordinarily gone into MgO, and the ammonia still process reaction that refluxes under gauge pressure 0.1～1.0MPa and 100～180 ℃ of temperature condition, total ammonia concentration＜0.05mol/L ends to the debris; Gained NH ₃Incorporate the NH that the A operation is reclaimed into ₃And CO ₂In recycle in the lump;

C, separate NaCl: will place under 100～180 ℃ of temperature evaporation concentration with crystallization NaCl, isolate the NaCl crystal after filtration again by B operation gained debris; Contain Mg in the concentrated solution after the filtration ²⁺〉=7.0wt%;

D, crystallization magnesium chloride: will continue to place drying crystalline under 300～350 ℃ of temperature through the filtering concentrated solution of C operation, get the hydrated magnesium chloride crystal;

E, magnesium chloride hydrolysis: will send into 800～1050 ℃ of temperature lower calcinations in calcining furnace inherence, hydrolysis magnesium chloride to obtain MgO and to emit HCl by D operation gained hydrated magnesium chloride crystal, gained MgO returns ammonia still process and recycles, and compressed recovery of HCl or water use it for anything else after absorbing and generating hydrochloric acid in addition.

Filtration of bicarbonate liquid in the above-mentioned synthetic system alkaline process is the filtration of bicarbonate liquid in solvay soda process or the soda and sociation center.And described drying crystalline magnesium chloride, its mode are evaporation drying crystallization or spraying drying crystallization.

The inventive method is owing to resolve into NH with the ammonium chloride in the filtration of bicarbonate liquid ₃With HCl and isolate NaCl, thus overcome the waste liquid (slag) that exists in the solvay soda process to the pollution of environment, and improved the utilization ratio of NaCl greatly; Solved effectively the connection alkaline process produce in the problem of byproduct ammonium chloride outlet difficulty, the serious restriction connection alkaline process soda ash development of producing, compare with background technology and not only to have saved the energy consumption that ammonium chloride is handled, but also reduced processing cost; In addition, it is reliable that the inventive method also has technology, combines with traditional synthetic alkali-making process closely and can effectively improve the characteristics such as economic benefit of producing soda ash.

Embodiment

A, pre-ammonia still process: with 2000ml filtration of bicarbonate liquid (wherein total NH ₃Concentration is 6.0mol/L, Na ⁺Concentration 1.96mol/L) places in the reactor, in gauge pressure and be under the pressure of 0.3Mpa and do not have the pre-ammonia still process of backflow under 130 ℃ of temperature, reclaim CO ₂, NH ₃, get debris 1800mL, wherein free NH ₃Concentration is 0.1mol/L;

B, ammonia still process reaction: in A operation gained debris, add 230.4g MgO, under gauge pressure 0.3MPa and 130 ℃ of temperature, take back stream and carry out the ammonia still process reaction, NH ₃And total NH ₃Concentration is the debris 1760mL of 0.05mol/L;

C, separate NaCl: with B operation gained debris place gauge pressure be under the pressure of 0.3Mpa and the 130 ℃ of temperature evaporation concentration get NaCl crystal 2 28.0g and filter after concentrated solution 1250mL, contain Mg in the concentrated solution ²⁺8.5wt%;

D, evaporative crystallization: D operation gained concentrated solution is continued evaporative crystallization get the 702.5g hydrated magnesium chloride under 330 ℃ of temperature;

E, magnesium chloride hydrolysis: the gained hydrated magnesium chloride is placed in the high temperature process furnances, gets MgO 228.5g at 900 ℃ of temperature lower calcinations, MgO returns the recycle of B operation after washing, HCl then absorbs the back, must concentration is that the hydrochloric acid 2200mL of 15.0wt% uses it for anything else in addition through water.

Claims

1. the treatment process of filtration of bicarbonate liquid in the synthetic system alkaline process, its method comprises:

A, pre-ammonia still process: the filtration of bicarbonate liquid that will synthesize in the alkali-making process places in the pre-ammonia steaming device, does not have the pre-ammonia still process processing that refluxes under gauge pressure 0.1～1.0MPa and 100～180 ℃ of temperature, with NH wherein ₄HCO ₃Resolve into NH ₃, CO ₂And H ₂O, free NH to the debris ₃Content＜0.1mol/L ends, NH ₃, CO ₂Reclaim stand-by;

B, ammonia still process: in the debris after the A operation is handled by with NH wherein ₄Amount that the required MgO weight of Cl complete reaction is 1.1～1.3 times adds MgO, under gauge pressure 0.1～1.0MPa and 100～180 ℃ of temperature condition, the ammonia still process that refluxes in ammonia steaming device reacts total NH to the debris ₃Concentration＜0.05mol/L ends; Gained NH ₃Incorporate the NH that the A operation is reclaimed into ₃And CO ₂In recycle in the lump;

C, separate NaCl: will place under 100～180 ℃ of temperature evaporation concentration with crystallization NaCl, isolate NaCl crystal, Mg in the concentrated solution after the filtration after filtration again by B operation gained debris ²⁺〉=7.0wt%;

D, crystallization magnesium chloride: will filter the gained concentrated solution through the C operation and continue to place drying crystalline under 300～350 ℃ of temperature, get the hydrated magnesium chloride crystal;

E, magnesium chloride hydrolysis: will send into 800～1050 ℃ of temperature lower calcinations in calcining furnace inherence, hydrolysis magnesium chloride to obtain MgO and to emit HCl by D operation gained hydrated magnesium chloride crystal; Gained MgO returns ammonia still process and recycles, and reclaims behind compressed recovery of HCl or the water absorption generation hydrochloric acid to use it for anything else in addition.

2. by the treatment process of filtration of bicarbonate liquid in claim 1, the described synthetic system alkaline process, it is characterized in that described filtration of bicarbonate liquid is the filtration of bicarbonate liquid in solvay soda process or the soda and sociation center.

3. by the treatment process of filtration of bicarbonate liquid in claim 1, the described synthetic system alkaline process, it is characterized in that described crystallization magnesium chloride, its mode are evaporation drying crystallization or spraying drying crystallization.