CN101028919B - Recovery of hydrofluoric acid - Google Patents
Recovery of hydrofluoric acid Download PDFInfo
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- CN101028919B CN101028919B CN2006100577796A CN200610057779A CN101028919B CN 101028919 B CN101028919 B CN 101028919B CN 2006100577796 A CN2006100577796 A CN 2006100577796A CN 200610057779 A CN200610057779 A CN 200610057779A CN 101028919 B CN101028919 B CN 101028919B
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Abstract
A process for recovering fluoric acid from the waste liquid generated during etching glass plate without generating scale includes such steps as adding sulfuric to said waste liquid, supplying the mixture to evaporator, heating, recovering the vapor to obtain coarse fluoric acid, distilling said coarse fluoric acid in the first distilling tower until the concentration of hydrogen fluoride in distillate is higher than the concentration of recovered fluoric acid to obtain refined fluoric acid.
Description
Technical field
The present invention relates to the recovery method of fluoric acid, specifically, relate to, reclaim the recovery method of fluoric acid of the batch processing mode of refining fluoric acid from the fluoric acid waste liquid that contains metal ingredient of the discharges such as etching work procedure of glass substrate by distillation method.
Background technology
In the etching of glass and glass substrate, using concentration for example is hydrofluoric acid (hereinafter referred to as " fluoric acid ") about 15 weight %, such fluoric acid, and (on-site) is by the high density fluoric acid preparation of diluting about 50 weight % with pure water usually at the scene.Then, utilize in the operation of fluoric acid, discharge the fluoric acid waste liquid that contains metal ingredient, but such waste liquid contains a large amount of fluoric acids that do not utilize in reaction, so expectation is with its recycling in above-mentioned etching etc.
Utilize in the operation at fluoric acid,, can enumerate the recovery method that uses the diffusion dialysis film as the method that reclaims fluoric acid from the fluoric acid waste liquid easily.In such fluoric acid recovery method, at first, use strainer or centrifugal separating device, reclaim as the fluoric acid waste liquid that separates the refining raw material of mud from the fluoric acid waste liquid, then, by utilizing the diffusion dialysis method of anionresin film filter, remove impurity from the fluoric acid waste liquid as the metal ion of solvent components or silicofluoric acid etc., obtain refining fluoric acid.The recovery method that is undertaken by above-mentioned diffusion dialysis method is can be with excellence aspect device miniaturization, the fluoric acid of can regenerating at the scene.
But, consider reclaiming the fluoric acid from the fluoric acid waste liquid, reclaim impurity fluoric acid still less with higher yield, same during with the manufacturing fluoric acid, preferably utilize distillation method to reclaim fluoric acid.But, in above-mentioned fluoric acid waste liquid, dissolving has the metal ingredient of Si, B, Al, Ca, Zr etc., reclaim by distillation method, metal ingredient in concentrated solution (separated spissated fluoric acid waste liquid) can be separated out, therefore can produce incrustation scale in comprising the system of retort, the equipment that makes can't turn round.In addition, in common fluoric acid manufacturing, in case make hydrogen fluoride by distillation method, it is big that equipment scale becomes, so the viewpoint from economy is difficult in field conduct.
Patent documentation 1: 2003-No. 12305 communiques of TOHKEMY
Summary of the invention
The present invention finishes in view of above-mentioned practical situation, its purpose is to provide a kind of distillation method of passing through, the fluoric acid waste liquid of discharging from the etching work procedure of glass substrate etc. reclaims the recovery method of fluoric acid of the batch processing mode of refining fluoric acid, it can not produce incrustation scale, can reclaim impurity refining fluoric acid still less with high yield, and can simplification device.
In order to solve above-mentioned problem, the recovery method of fluoric acid of the present invention, be to pass through distillation method, reclaim the recovery method of fluoric acid of batch processing mode of the refining fluoric acid of normality from the fluoric acid waste liquid that contains metal ingredient, it is characterized in that, by utilizing evaporating kettle heating fluoric acid waste liquid, thick fluoric acid is taken out as steam, recycle the operation that distillation tower distills the distillate of thick fluoric acid simultaneously, the hydrogen fluoride concentration of distillate is that recycle-water upper limit concentration is when following, this distillate is reclaimed as recycle-water, and liquid returns evaporating kettle at the bottom of the tower; When the hydrogen fluoride concentration of distillate is higher than recycle-water upper limit concentration and reclaims concentration less than fluoric acid, this distillate is reclaimed as intermediate liquid; The hydrogen fluoride concentration of distillate reclaims concentration when above at fluoric acid, this distillate is reclaimed as refining fluoric acid, and when the fluoric acid waste liquid of heating evaporation still, and in this fluoric acid waste liquid, interpolation is used to suppress the sulfuric acid of the capacity that metal ingredient separates out.
Promptly, in the present invention, utilize evaporating kettle heating fluoric acid waste liquid, the thick fluoric acid of containing metal composition is hardly taken out as steam, utilize the further thick fluoric acid of distillation of distillation tower simultaneously, in reclaiming by the operation of purified distillate, utilize evaporating kettle when the fluoric acid waste liquid takes out thick fluoric acid, by in the fluoric acid waste liquid, adding sulfuric acid, utilize metal ingredient before separating out in the spissated fluoric acid waste liquid of evaporating kettle (concentrated solution) by sulfuric acid dissolution, thus, the incrustation scale in the still that can avoid evaporating prevents the decline of heat transfer efficiency.Then, from distillation tower recovery distillate the time, switch reclaimer operation by hydrogen fluoride concentration according to the distillate of supplying with distillation tower, be respectively formed at fluoric acid and utilize the recycle-water that can be used in the operation diluting etc., have intermediate liquid lower concentration, that can be used as the raw material in the next batch treatment that is lower than aimed concn and the refining fluoric acid of aimed concn.
Recovery method according to fluoric acid of the present invention, when utilizing evaporating kettle to evaporate thick fluoric acid, in the fluoric acid waste liquid, add sulfuric acid, be dissolved in the metal ingredient in the spissated fluoric acid waste liquid (concentrating spent liquor), therefore, can avoid evaporating in the still incrustation scale and can prevent that heat transfer efficiency from descending, its result can reclaim impurity refining fluoric acid still less with high yield.In addition, according to fluoric acid recovery method of the present invention, only each 1 evaporating kettle of combination and distillation tower constitute the fluoric acid retrieving arrangement, then, directly fluoric acid is taken out as thick fluoric acid, switch reclaimer operation and reclaim spissated refining fluoric acid from the fluoric acid waste liquid, therefore, can simplification device.
Description of drawings
Fig. 1 is the schema of the formation example of the recovery method of fluoric acid of the present invention and the major portion that is illustrated in the fluoric acid retrieving arrangement that is suitable in the enforcement of this recovery method.
Fig. 2 is the longitdinal cross-section diagram of an example of the evaporating kettle heating unit in the expression fluoric acid retrieving arrangement.
Fig. 3 is the longitdinal cross-section diagram of other example of the evaporating kettle heating unit in the expression fluoric acid retrieving arrangement.
Fig. 4 is the longitdinal cross-section diagram of other example of the evaporating kettle heating unit in the expression fluoric acid retrieving arrangement.
Nomenclature
1... evaporating kettle, 11... chuck, 12... tubular heat exchanger, 13... tube exchanger, 14... water vapour supply-pipe, 15... water vapour vent pipe, 2... distillation tower, 40... distillate container, 41... recycle-water container, 42... intermediate liquid container, 43... refining fluoric acid container, 3... cooler condenser, 71... raw material path, 72... sulfuric acid supply passageway, 73... thick fluoric acid path, 74... waste liquid drain passageway, 81... liquid current return circuit at the bottom of the tower, 82... vapor passageway, 83... phlegma path, 84... current return circuit, 85... recycle-water path, 86... intermediate liquid path, 87... refining fluoric acid path, 88... exhaust channel, 91... recycle-water takes out path, 92... intermediate liquid current return circuit, 93... refining fluoric acid takes out path
Embodiment
The embodiment of fluoric acid recovery method of the present invention (hereinafter referred to as " recovery method ") is described based on drawing.Recovery method of the present invention is to reclaim the recovery method of the batch processing mode of refining fluoric acid by distillation method from the fluoric acid waste liquid uses such as etching of glass and glass substrate, that contain metal ingredient at least, uses fluoric acid retrieving arrangement enforcement shown in Figure 1.Fig. 1 is the schema of formation example of the major portion of expression recovery method of the present invention and the fluoric acid retrieving arrangement that is suitable in the enforcement of this recovery method.Fig. 2～Fig. 4 is the longitdinal cross-section diagram of example of the heating unit of the evaporating kettle in the expression fluoric acid retrieving arrangement.Omitted among the figure and be used to control fluidic switching valve and flow rate regulating valve.In addition, in the present invention, each hydrogen fluoride concentration of liquid at the bottom of fluoric acid waste liquid, thick fluoric acid and refining fluoric acid and distillate, the tower is called " concentration ", in addition, the water of the impurity beyond the not fluoric-containing acid that distillation is reclaimed is called recycle-water.
At first, the fluoric acid retrieving arrangement that is used to implement recovery method of the present invention is described.Be applicable to fluoric acid retrieving arrangement of the present invention as shown in Figure 1, mainly possess: from the fluoric acid waste liquid that should handle thick fluoric acid is taken out as steam, separate the evaporating kettle (1) of concentrating spent liquor simultaneously; The thick fluoric acid that obtains with distillation, be separated into the distillation tower (2) of liquid at the bottom of distillate (recycle-water, intermediate liquid or refining fluoric acid) and the tower.In addition, in the equipment class of above-mentioned evaporating kettle (1), distillation tower (2) and container described later and each path (pipe arrangement) etc., use to have erosion resistance, that make with fluoro-resin usually or apply or the equipment of liner with fluoro-resin.
Evaporating kettle (1) is to be used to the steaming plant that heats the fluoric acid waste liquid, reclaim thick fluoric acid with vapor state.Top in evaporating kettle (1), be connected with the raw material path (71) of the fluoric acid waste liquid that importing should handle, take out evaporation thick fluoric acid thick fluoric acid path (73) and add vitriolic sulfuric acid supply passageway (72) as described later and utilize the isolating tower of distillation tower (2) at the bottom of liquid return liquid current return circuit (81) at the bottom of the tower that this evaporating kettle flows through, utilize distillation tower (2) to return the intermediate liquid current return circuit (92) that evaporating kettle (1) is flowed through as the lower concentration distillate of intermediate liquid recovery.In addition, the bottom in evaporating kettle (1) is provided with and discharges concentrating spent liquor, promptly will contain the waste liquid drain passageway (74) of the spissated fluoric acid waste liquid of metal ingredient when batch treatment finishes.
The structure of evaporating kettle (1) can heat the fluoric acid waste liquid that holds by heating unit.As the heating unit that uses at evaporating kettle (1), can fully evaporate from the fluoric acid waste liquid of answering treatment capacity in the scope of thick fluoric acid, can use various heating units, for example, can enumerate the chuck (11), tubular heat exchanger (12), tube exchanger (13) etc. of Fig. 2～as shown in Figure 4.
That is, evaporating kettle shown in Figure 2 (1) is provided with the chuck (11) that constitutes steam chamber in the periphery of kettle, form with water vapour supply in the above-mentioned steam chamber, the style of the fluoric acid waste liquid of heating kettle inside.Evaporating kettle shown in Figure 3 (1) is that the tubular heater exchhanger (12) that a plurality of heat-transfer pipe boundlings constitute is inserted the evaporating kettle that leads in still inside, by water vapour being supplied in each above-mentioned heat-transfer pipe the style of the fluoric acid waste liquid of heating kettle inside.In addition, evaporating kettle shown in Figure 4 (1) is to have in the still internal configuration heat-transfer pipe is coiled the stacked tube coil type heat exchanger (13) that constitutes for coiled type, by water vapour being supplied in the above-mentioned heat-transfer pipe style of the fluoric acid waste liquid of heating kettle inside.Symbol among each figure (14) and (15) are represented water vapour supply-pipe and water vapour vent pipe respectively.
In addition, though it is not shown, but in order to improve heat-exchange capacity, in above-mentioned evaporating kettle (1), periphery at the still body is provided with chuck shown in Figure 2 (11), and tubular heater exchhanger shown in Figure 3 (12) or tube coil type heat exchanger (13) shown in Figure 4 are arranged in the still internal configuration, in the steam chamber that water vapour is supplied to chuck (11), simultaneously water vapour is supplied in the heat-transfer pipe of tubular heater exchhanger (12) or tube coil type heat exchanger (13), thus, can form from the style of the inside and outside heating fluoric acid waste liquid of still.Wherein, as tubular heater exchhanger shown in Figure 3 (12), " PFA shell and-tube heat exchanger " (trade(brand)name) that can utilize the river ヒ ュ that for example forms sediment-テ ッ Network society to produce, as tube coil type heat exchanger shown in Figure 4 (13), " PFA tube coil type heat exchanger " (trade(brand)name) that can utilize the said firm to produce.
Distillation tower (2) is used for the refining thick fluoric acid that utilizes evaporating kettle (1) to take out of distillation, Separation and Recovery is the water of fluoric-containing acid (recycle-water) hardly, Separation and Recovery reclaims the lower concentration fluoric acid (intermediate liquid) of concentration (aimed concn) less than fluoric acid, and Separation and Recovery reclaims refining fluoric acid more than the concentration (aimed concn) at fluoric acid.Distillation tower (2) is by at existing known distillation tower, promptly the plate column of the support of using by the gas-to-liquid contact that a plurality of porous plate supports etc. are set in void tower (column plate), in void tower, be filled with the formations such as packed tower of irregular or regular weighting material.
The thick fluoric acid that the structure of distillation tower (2) should be handled is supplied with tower bottom by above-mentioned thick fluoric acid path (73) from evaporating kettle (1).In addition, be provided with liquid at the bottom of the tower of separating and condensing at the tower bottom of distillation tower (2), promptly by difference of height, thick fluoric acid that is concentrated or debris are returned liquid current return circuit (81) at the bottom of the tower that evaporating kettle (1) flows through.
On the other hand, the cat head at distillation tower (2) is provided with the vapor passageway (82) of the steam (steam of recycle-water, intermediate liquid or refining fluoric acid) of fractionation by distillation being taken out, supplies with cooler condenser (3).As cooler condenser (3), usually use in the pipe of a plurality of heat-transfer pipes that are formed with a plurality of paths circulation refrigerant and outer by the liquefy multibarrel condenser of above-mentioned condensability steam of condensability steam (steam of fractionation by distillation) at pipe.Be provided with in the bottom of cooler condenser (3) as recycle-water, intermediate liquid or the refining fluoric acid liquor charging of the condensation of distillate phlegma path (83), be provided with the exhaust channel (88) that uncondensable gas is vented to the device of removing the evil on the top of cooler condenser (3) to distillate container (40).
Above-mentioned distillate container (40) is to store the container that utilizes distillation tower (2) fractionation by distillation and cool off the refining fluoric acid of the recycle-water, intermediate liquid or the high density that obtain with cooler condenser (3).This distillate container (40), when distillation procedure, for the part of recycle-water, intermediate liquid or refining fluoric acid is returned distillation tower (2) as backflow, so, be connected the cat head side of distillation tower (2) by current return circuit (84).
In addition, in order to recycle recycle-water, intermediate liquid and the refining fluoric acid that distillation tower (2) obtains, in above-mentioned current return circuit (84), branch is provided with recycle-water path (85), intermediate liquid path (86) that reclaims intermediate liquid that reclaims recycle-water and the refining fluoric acid path (87) that reclaims refining fluoric acid, and these recycle-water paths (85), intermediate liquid path (86) and refining fluoric acid path (87) are connected to recycle-water container (41), the intermediate liquid container (42) that stores intermediate liquid that stores recycle-water and store on the refining fluoric acid container (43) of refining fluoric acid.
Then, make with extra care fluoric acid and recycle-water in order to utilize supplies such as operation to fluoric acid, recycle-water container (41) is provided with recycle-water taking-up path (91), refining fluoric acid container (43) is provided with refining fluoric acid taking-up path (93).In addition, when the batch treatment operation of next time, for intermediate liquid is used as part material, intermediate liquid container (42) is provided with the intermediate liquid current return circuit (92) that leads to evaporating kettle (1).
Moreover, in fluoric acid retrieving arrangement shown in Figure 1, in order to control the flow and the reflux ratio of liquid and distillate at the bottom of the tower in the distillation procedure, and for as described later, switch recycle-water reclaimer operation, intermediate liquid reclaimer operation and refining fluoric acid reclaimer operation according to the concentration of distillate, the downstream side of top of tower, vapor passageway (82) or the cooler condenser (3) of for example distillation tower (2) be provided with measure distillate concentration hydrogen fluoride concentration meter (omitting diagram).Then, by the control device of loading operation program, based on the treatment condition of input in advance and the determination data of above-mentioned hydrogen fluoride concentration meter, the heating unit of control evaporating kettle (1), the switching of each path, switching, flow adjustment etc.
In addition, as above-mentioned hydrogen fluoride concentration meter,, use it is scaled the conductivity type densitometer of hydrogen fluoride concentration with the conductivity (electric conductivity) in the way of electromagnetic induction METHOD FOR CONTINUOUS DETERMINATION fluoric acid; Or calculate the ultrasonic propagation velocity of measuring in the fluoric acid, based on the relation of the ultrasonic propagation velocity in ready-made specified temperature, the concentration, detect the ultrasonic type densitometer of hydrogen fluoride concentration; Or calculate ultrasonic propagation velocity and the electromagnetism electric conductivity of measuring in the fluoric acid, the relation (matrix) based on ultrasonic propagation velocity in ready-made specified temperature, the concentration and electromagnetism electric conductivity detects hydrogen fluoride concentration and H
2SiF
6Ultrasonic type multicomponent densitometer etc. impurity concentration.
Particularly, above-mentioned ultrasonic type multicomponent densitometer, by ultrasonic propagation velocity and the electromagnetism electric conductivity in the solution of measuring certain temperature, can be in real time and measure the concentration of 2 compositions of 3 composition system solutions simultaneously.Promptly, the multicomponent densitometer is based on if determine the temperature of solution, corresponding to the concentration of each composition, and the unique specific principle of ultrasonic propagation velocity in the liquid and electromagnetism electric conductivity, when being applicable to the mensuration of fluoric acid concentration, by prepare in advance as matrix at each hydrogen fluoride and H
2SiF
6Under the concentration, the ultrasonic propagation velocity of measuring in advance and the relation of electromagnetism electric conductivity based on above-mentioned matrix, are correctly calculated hydrogen fluoride concentration and H from measured value at a certain temperature
2SiF
6Concentration.
For example, as above-mentioned conductivity type densitometer, " induction concentration umformer MBM-102A type " (trade(brand)name) that can use East Asia デ イ-ヶ-ヶ-company to produce, as the ultrasonic type densitometer, " ultrasonic liquid densitometer FUD-1 Model-12 " (trade(brand)name) that can use industrial of Fuji to produce, in addition, as ultrasonic type multicomponent densitometer, the commodity that can use industrial of Fuji to produce are called the densitometer of " FUD-1 Model-52 ".
Then, the recovery method of the present invention that uses above-mentioned fluoric acid retrieving arrangement is described.As being applicable to fluoric acid waste liquid of the present invention, can enumerate from for example implementing etching and clean or carry out the fluoric acid that the incrustation scale of foundry goods comes off and utilize the waste liquid of discharging the operation at glass or glass substrate.This fluoric acid waste liquid, contain silica composition and metal ingredient, promptly by with the reaction of the object being treated composition of etched material etc., as the composition of various fluoride dissolutions or crystallization or the resultant of reaction of generation.Particularly, contain compositions such as Si, B, Al, Ca, Fe, Sr, Zr, K, Na, Mg.In addition, be about 0.1～20 weight % as for example concentration of the fluoric acid waste liquid of etching solution use usually.
In recovery method of the present invention, will supply with the fluoric acid waste liquid of evaporating kettle (1) as 1 batch treatment by raw material path (71) in advance basically.Then, in 1 batch such processing, utilize evaporating kettle (1) heating to contain the fluoric acid waste liquid of metal ingredient, the thick fluoric acid of containing metal composition is hardly taken out as steam, utilize distillation tower (2) to distill thick fluoric acid simultaneously, reclaim the operation of distillate continuously.That is, recovery method of the present invention comprises: utilize evaporating kettle (1) heating fluoric acid waste liquid, take out the thick fluoric acid evaporization process of thick fluoric acid as steam; With utilize distillation tower (2) to distill thick fluoric acid, as the distillation process of the refining fluoric acid of distillate Separation and Recovery recycle-water, intermediate liquid or normality.
In the present invention, the fluoric acid waste liquid of distillation lower concentration, can obtain the refining fluoric acid of the following expectation concentration of azeotropic concentration, in the following description, enumerate the example that reclaims the refining fluoric acid of concentration 30% from the fluoric acid waste liquid of concentration 5%.In addition, in the present invention, so-called recycle-water upper limit concentration is the upper limit of the concentration (hydrogen fluoride concentration) of the recycle-water that can extensively utilize as dilution water, and it is to utilize aimed concn necessary in the operation at fluoric acid that so-called refining fluoric acid reclaims concentration, and these concentration are suitably set according to necessary condition.
At thick fluoric acid evaporization process, promptly utilize in the operation of evaporating kettle (1) heating fluoric acid waste liquid, from the fluoric acid waste liquid with vapor state only hardly the fluoric acid of containing metal composition as thick fluoric acid separation.Concrete, in evaporating kettle (1), fluoric acid waste water utilization Fig. 2 that should handle, for example concentration 5 weight %～heating unit heating shown in Figure 4, evaporation separates the thick fluoric acid as distillating material.At this moment, in the present invention, in order to prevent to follow concentrating of fluoric acid waste liquid in the evaporating kettle (1), the metal ingredient in this fluoric acid waste liquid (concentrating spent liquor) is separated out, and adds the sulfuric acid that is used to suppress the capacity that metal ingredient separates out in the fluoric acid waste liquid.
Sulfuric acid is supplied with evaporating kettle (1) by sulfuric acid supply passageway (72), and the fluoric acid waste liquid of evaporating kettle (1) according to metal ingredient that contains and concentration thereof, adds the metal ingredient in the capacity dissolving fluoric acid waste liquid at least relatively.As the vitriolic addition means, can add certain density sulfuric acid continuously with certain flow, also can add the sulfuric acid of high density off and on.As mentioned above, in the heating operation that utilizes evaporating kettle (1), when making fluoric acid evaporation concentration fluoric acid waste liquid, by adding sulfuric acid, can in fluoric acid waste liquid (concentrating spent liquor), metal ingredient be maintained dissolved state, therefore, can avoid evaporating incrustation scale in the still (1) adheres to decline with the heat transfer efficiency of heating unit.
In the heating operation that utilizes evaporating kettle (1), dissolve silica composition and metal ingredient in the fluoric acid waste liquid by taking out with steam, can separate the thick fluoric acid about above-mentioned for example concentration free from foreign meter 5～7 weight %.Then, as the separated thick fluoric acid of steam, supply with distillation tower (2) by thick fluoric acid path (73).
In distillation process, promptly utilize in the operation of the thick fluoric acid of distillation tower (2) distillation, utilize the thick fluoric acid of distillation tower (2) distillation from the steam of evaporating kettle (1) supply.When utilizing the distillation procedure of distillation tower (2), the specified pressure that intrasystem pressure is remained on below the normal atmosphere carries out usually.In distillation procedure, according to the thick fluoric acid concentration of supplying with and the distillate concentration of available distillation tower (2), above-mentioned distillate is reclaimed in difference.
Promptly, in the present invention, heating operation by utilizing evaporating kettle (1) and utilize the distillation procedure of distillation tower (2), the distillate concentration of distillation tower (2) are recycle-water upper limit concentration (for example 0.1 weight %) when following, with this distillate as recycle-water recovery and tower at the bottom of liquid return evaporating kettle; When the distillate concentration of distillation tower (2) is higher than above-mentioned recycle-water upper limit concentration and reclaims concentration (for example 30 weight %) less than fluoric acid, this distillate is reclaimed as intermediate liquid; The concentration of the distillate of distillation tower (2) reclaims this distillate when above-mentioned fluoric acid recovery concentration is above as refining fluoric acid.
In the distillation procedure of distillation tower (2), as the concentration of above-mentioned thick fluoric acid when low when concentration 5～7 weight % left and right sides (for example), because the water in thick fluoric acid is separated as steam at first, so the concentration of distillate reclaims this distillate in being no more than above-mentioned recycle-water upper limit range of concentrations as recycle-water.Concrete, utilize the steam of distillation tower (2) fractionation by distillation to take overhead out, supply to cooler condenser (3) by vapor passageway (82), utilize the liquefaction of this cooler condenser after,, be stored in this distillate container to distillate container (40) by phlegma path (83) liquor charging.Then, be stored in the distillate of distillate container (40), because below recycle-water upper limit concentration, so, by recycle-water path (85), be contained in the recycle-water container (41) as recycle-water one by one.
On the other hand, when carrying out the reclaimer operation of recycle-water, because liquid cooling is coagulated at the bottom of the spissated thick fluoric acid of the tower bottom of distillation tower (2) is as tower, so, at the bottom of this tower liquid by tower at the bottom of liquid current return circuit (81) return evaporating kettle (1), can improve the concentration of the raw material fluoric acid waste liquid of evaporating kettle (1).Moreover, as mentioned above, initial fluoric acid waste liquid is still as during above-mentioned lower concentration, the amount of the refining fluoric acid of the available high density of capacity of evaporating kettle (1) is few relatively, therefore from improving the viewpoint of running efficiency, when carrying out the recovery of recycle-water, replenish the fluoric acid waste liquid, make that the liquid measure in the evaporating kettle becomes roughly certain amount to evaporating kettle (1).As mentioned above, when the reclaimer operation of recycle-water, liquid turns back in the evaporating kettle (1) at the bottom of the spissated tower of additional fluoric acid waste liquid and distillation tower (2) in evaporating kettle (1), therefore, can store for example high density fluoric acid waste liquid of 20～30 weight % in evaporating kettle (1).
The distillation procedure that continues to utilize the heating operation of evaporating kettle (1) and utilize distillation tower (2), the concentration of the fluoric acid waste liquid of evaporating kettle (1) rises, from the temporary transient fluoric acid steam that is higher than recycle-water upper limit concentration (for example 0.1 weight %) and reclaims concentration (for example 30 weight %) less than fluoric acid that separates of the cat head of distillation tower (2).Therefore, the concentration of distillate reclaims this distillate when above-mentioned concentration range as intermediate liquid.Concrete, same during with recycle-water, to utilize distillation tower (2) fractionation by distillation and with the distillate liquor charging of cooler condenser (3) liquefaction in distillate container (40), in this distillate container, store, then, by intermediate liquid path (86), be contained in the intermediate liquid container (42) as intermediate liquid one by one
Moreover, continue to utilize the heating operation of evaporating kettle (1) and utilize the distillation procedure of distillation tower (2), from the fluoric acid steam of the cat head separation of high-concentration of distillation tower (2).At this moment, the concentration of distillate is that fluoric acid reclaims concentration (for example 30 weight %) when above, and this distillate is reclaimed as refining fluoric acid.Concrete, same during with recycle-water and intermediate liquid, to utilize distillation tower (2) fractionation by distillation and with the distillate liquor charging of cooler condenser (3) liquefaction in distillate container (40), in this distillate container, store, then, by refining fluoric acid path (87), the refining fluoric acid of conduct one by one is contained in the refining fluoric acid container (43).
In addition, when carrying out, be stored in the part distillate in the distillate container (40), as refluxing, return in the distillation tower (2) with certain flow by current return circuit (84) as above-mentioned a series of heating distillation procedure.In addition, when intermediate liquid reclaims and makes with extra care fluoric acid and reclaims, close liquid current return circuit (81) at the bottom of the tower, liquid all remains on when batch treatment finishes in the distillation tower (2) at the bottom of the tower that contains holdup capacity part (concentrating the purified fluoric acid) in the distillation tower (2).Then, when next batch treatment,, can improve the rate of recovery by making that liquid turns back to evaporating kettle (1) at the bottom of the above-mentioned tower.
The reclaimer operation of recycle-water, intermediate liquid and refining fluoric acid, as mentioned above, undertaken by switching recycle-water path (85), intermediate liquid path (86) and refining fluoric acid path (87), the blocked operation of these paths, in order to remedy the skew of answering time, by going up capping value and lower value control at each aimed concn (recycle-water upper limit concentration and fluoric acid reclaim concentration).When finishing aforesaid 1 batch treatment, the spissated fluoric acid waste liquid that contains metal ingredient remains in the evaporating kettle (1), but this fluoric acid waste liquid is discharged by waste liquid drain passageway (74) as the bottom of concentrating spent liquor from evaporating kettle (1), and liquor charging carries out harmless treatment to the device of removing the evil.
By above-mentioned distillation and reclaimer operation, be fluoric acid waste liquid about 5 weight % from for example concentration, can reclaim concentration is that about 20% intermediate liquid and concentration are the refining fluoric acid more than 30% less than recycle-water, the concentration of 0.1 weight %.The refining fluoric acid that obtains in refining fluoric acid container (43) takes out path (93) by refining fluoric acid and supplies to the operation of for example utilizing fluoric acid.In addition, the recycle-water of the recycle-water container (41) that obtains at first takes out path (91) by recycle-water, and what supply to fluoric acid as required utilizes operation etc.
The intermediate liquid that reclaims in intermediate liquid container (42) supplies to evaporating kettle (1) in next batch treatment.When handling next time, supply to evaporating kettle (1), in the fluoric acid waste liquid, mix by the intermediate liquid that will reclaim, can further improve the rate of recovery.In addition, during the refining fluoric acid of the refining fluoric acid container (43) that obtains in utilization, the recycle-water of the recycle-water container (41) by Separation and Recovery will be made with extra care fluoric acid and be diluted to normality, also can effectively utilize recycle-water.Wherein, in the present invention, as mentioned above, switch reclaimer operation based on the distillate concentration of distillation tower (2), when therefore being higher than fluoric acid and reclaiming concentration, when distillation procedure as the concentration of the fluoric acid waste liquid of the evaporating kettle (1) of raw material, selective finishing fluoric acid path (87) is from the refining fluoric acid of initial recovery.
As mentioned above, according to recovery method of the present invention, when utilizing evaporating kettle (1) from the thick fluoric acid of fluoric acid waste liquid evaporation, in the fluoric acid waste liquid, add sulfuric acid, metal ingredient is dissolved in the spissated fluoric acid waste liquid (concentrating spent liquor), the metal ingredient that can avoid evaporating in the fluoric acid waste liquid of still (1) is separated out, the incrustation scale in the still (1) that can avoid evaporating thus and can prevent the decline of heat transfer efficiency.Secondly, utilize distillation tower (2) further to distill the few thick fluoric acid of impurity, therefore can reclaim impurity refining fluoric acid still less with high yield.
In addition, according to recovery method of the present invention, use 1 group of evaporating kettle (1) and distillation tower (2), distillate concentration according to distillation tower (2) is switched reclaimer operation, can be recovered in fluoric acid respectively and utilize the recycle-water that can be used in dilution etc. in the operation, have and be lower than fluoric acid and reclaim intermediate liquid lower concentration, that can use as raw material in next batch treatment of concentration and the refining fluoric acid that fluoric acid reclaims concentration.In other words, only each 1 evaporating kettle (1) of combination and distillation tower (2) just can constitute the fluoric acid retrieving arrangement, secondly, do not have as the existing method manufacturing hydrogen fluoride of making fluoric acid, from the fluoric acid waste liquid fluoric acid is directly taken out as thick fluoric acid, switch reclaimer operation and reclaim spissated refining fluoric acid, therefore can simplification device.Thus, can utilize in the operation of fluoric acid, be easy to reclaim at the scene fluoric acid at glass substrate etching etc.
Embodiment
Use fluoric acid retrieving arrangement shown in Figure 1, the fluoric acid waste liquid of discharging from the etching work procedure of glass substrate reclaims refining fluoric acid.In the fluoric acid retrieving arrangement, the useful volume of evaporating kettle (1) is that the useful volume of 1000cc, distillation tower (2) is 300cc.As the fluoric acid waste liquid of handling, preparing concentration is 10 weight %, and the metal ingredient concentration of Si, B, Al, Ca, Zt etc. is the waste liquid of 1 weight %.
In the heating operation in evaporating kettle (1), under the pressure condition of 100Torr, 74 ℃ the heating 800cc the fluoric acid waste liquids, with thick fluoric acid as vapor recovery, supply to distillation tower (2).At this moment, in evaporating kettle (1), with 3cc/ hour flow, add up to add 98% sulfuric acid of 12cc.On the other hand, in the distillation procedure of distillation tower (2), recycle-water upper limit concentration is set at 200ppm, fluoric acid is reclaimed concentration is set at 10 weight %, distill thick fluoric acid, reclaim recycle-water at first.In addition, when the separation of recycle-water, liquid current return circuit (81) returns evaporating kettle (1) at the bottom of utilizing at the bottom of the isolating tower of distillation tower (2) liquid by tower, improves the concentration of the fluoric acid waste liquid of evaporating kettle (1), simultaneously will be in evaporating kettle (1) adds to as the fluoric acid waste liquid of raw material that to add up to be 1600cc.By the reclaimer operation of above-mentioned recycle-water, can obtain the recycle-water of 1201cc in recycle-water container (41).
Therefore then, in the distillation procedure of distillation tower (2), the concentration of distillate reaches 200ppm, closes liquid current return circuit (81) at the bottom of the tower, and the path with distillate switches to intermediate liquid path (86), intermediate liquid is recovered in the intermediate liquid container (42) simultaneously.In the reclaimer operation of intermediate liquid, in intermediate liquid container (42), can obtain the intermediate liquid that 350cc concentration is 3.0 weight %.Continue distillation procedure again, when the concentration of distillate reaches 10 weight %, the path of distillate is switched to refining fluoric acid path (87), will make with extra care fluoric acid and be recovered in the refining fluoric acid container (43).Its result can obtain the refining fluoric acid of 680cc concentration 25 weight % in refining fluoric acid container (43).
Then, above-mentioned sequence of operations repeatedly after 10 batches, is checked evaporating kettle (1), distillation tower (2) and pipe arrangement class, confirm not produce incrustation scale.In addition, be determined at the impurity of the refining fluoric acid that reclaims in the refining fluoric acid container (43), metal ingredient concentration is below the 0.1ppm.
Claims (5)
1. the recovery method of a fluoric acid, be to pass through distillation method, the recovery method of the fluoric acid of the batch processing mode of the refining fluoric acid of recovery normality from the fluoric acid waste liquid that contains metal ingredient, it is characterized in that, by utilizing evaporating kettle heating fluoric acid waste liquid, thick fluoric acid is taken out as steam, recycle the operation that distillation tower distills the distillate of thick fluoric acid simultaneously, when the hydrogen fluoride concentration of distillate when recycle-water upper limit concentration is following, this distillate is reclaimed as recycle-water, and liquid returns in the evaporating kettle at the bottom of the tower; When the hydrogen fluoride concentration of distillate is higher than recycle-water upper limit concentration and reclaims concentration less than fluoric acid, this distillate is reclaimed as intermediate liquid; When the hydrogen fluoride concentration of distillate reclaims concentration when above at fluoric acid, this distillate is reclaimed as refining fluoric acid, and when the fluoric acid waste liquid of heating evaporation still, the sulfuric acid of the capacity that interpolation inhibition metal ingredient is separated out in this fluoric acid waste liquid.
2. the recovery method of fluoric acid as claimed in claim 1 is characterized in that, when recycle-water is reclaimed, replenishes the fluoric acid waste liquid in evaporating kettle.
3. the recovery method of fluoric acid as claimed in claim 1 or 2 is characterized in that, in next batch treatment, the intermediate liquid that is reclaimed is supplied with evaporating kettle.
4. the recovery method of fluoric acid as claimed in claim 1 or 2 is characterized in that, utilizes the recycle-water that is reclaimed will make with extra care fluoric acid and is diluted to normality.
5. the recovery method of fluoric acid as claimed in claim 3 is characterized in that, utilizes the recycle-water that is reclaimed will make with extra care fluoric acid and is diluted to normality.
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| CN2006100577796A CN101028919B (en) | 2006-02-27 | 2006-02-27 | Recovery of hydrofluoric acid |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US5632866A (en) * | 1994-01-12 | 1997-05-27 | Fsi International, Inc. | Point-of-use recycling of wafer cleaning substances |
| CN1504419A (en) * | 2002-11-28 | 2004-06-16 | �G�ֻ�е��������˾ | Hydrofluoric acid wastewater treatment method and device |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5632866A (en) * | 1994-01-12 | 1997-05-27 | Fsi International, Inc. | Point-of-use recycling of wafer cleaning substances |
| CN1504419A (en) * | 2002-11-28 | 2004-06-16 | �G�ֻ�е��������˾ | Hydrofluoric acid wastewater treatment method and device |
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