CN102642870A - Method for continuously neutralizing and decontaminating sodium chromate alkali solution - Google Patents

Method for continuously neutralizing and decontaminating sodium chromate alkali solution Download PDF

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CN102642870A
CN102642870A CN201110153029XA CN201110153029A CN102642870A CN 102642870 A CN102642870 A CN 102642870A CN 201110153029X A CN201110153029X A CN 201110153029XA CN 201110153029 A CN201110153029 A CN 201110153029A CN 102642870 A CN102642870 A CN 102642870A
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sodium
neutralization reactor
neutralization
reactor
sodium chromate
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CN102642870B (en
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李先荣
陈宁
张国庆
王方兵
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SICHUAN AN COUNTY YINHE JIANHUA (GROUP) CO Ltd
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Abstract

The invention relates to a method for continuously neutralizing and decontaminating a sodium chromate alkali solution. The method comprises the following step of: adding a neutral aqueous solution containing sodium chromate and an optional crystal seed which are used as bottom materials in a neutralization reactor for realizing neutralization and decontamination based on carbon dioxide as a neutralizing agent or chromium-containing acidic wastewater which is produced in the process of producing sodium bichromate from sodium chromate, a pre-acidification solution, an acidification solution, a sodium bichromate mother liquid, a sodium dichromate aqueous solution and inorganic acid, or any mixture of the former neutralizing agents. Through the control over the concentration, temperature, pH value and stirring speed of a reaction liquid, precipitate obtained by the method is large in particle and rapid in sedimentation speed; aluminum mud is good in filtering property and is easy to wash; and the content of hexavalent chromium in the aluminum mud in greatly reduced, thereby reducing the discharge amount of the aluminum mud. In addition, the neutralization reactor the upper part of which is provided with an overflowing port is adopted for neutralization reaction, so that the automation and continuty of the neutralization and decontamination process of the sodium chromate alkali solution are realized.

Description

A kind of chromium acid sodium alkaline liquid continuously in the method for removal of impurities
Technical field
The present invention relates to a kind of chromium acid sodium alkaline liquid continuously in the method for removal of impurities.
Background technology
Sodium dichromate is a kind of basic Inorganic Chemicals, is mainly used in chromic salts products such as making chromic trioxide, basic chromic sulfate, chromoxide green, is widely used in industries such as printing and dyeing, plating.
The production of sodium dichromate comprises that mainly the preparation of Sodium chromate-51Cr and Sodium chromate-51Cr change these two processes of sodium dichromate into.At present, domestic majority manufacturer still all is to be auxiliary material with rhombspar, Wingdale and chromium slag, and with chromite and soda ash oxidizing roasting at high temperature, infuse goes out chromium acid sodium alkaline liquid, then changes Sodium chromate-51Cr into sodium dichromate with sulfuric acid again.
In the sodium dichromate production process, chromium acid sodium alkaline liquid contains impurity such as sodium aluminate, free alkali, water glass and calcium, magnesium, iron, the trivalent chromium of non-quantitative.Tradition neutralization method gained aluminium mud deposit seeds is little, separation difficulty, and the sexavalent chrome band in the aluminium mud decreases high; If it is unclean that impurity such as the aluminium in the feed liquid, silicon separate, even can influence the quality of product.Because impurity such as silicon, aluminium have formed the coexistence system in chromium acid sodium alkaline liquid, influenced the degree that removes of impurity in the feed liquid.The processing condition of control chromium acid sodium alkaline liquid removal of impurities reduce the foreign matter content in the feed liquid as far as possible, are effective measures that improve the quality of products.
Removal of impurities mechanism involved in the present invention is following:
(1) chromium acid sodium alkaline liquid with in the neutralizing agent and the time, sodium aluminate generation hydrolytic action, the disassociation formula is:
Figure BSA00000513144100011
The solubility product of white lake is:
Can know that by following formula the solubility product of aluminum hydroxide precipitation is not only relevant with aluminum ions concentration, and receive hydrionic concentration affects.Because aluminum ions concentration change is little in the chromium acid sodium alkaline liquid, therefore, mainly by the Sorensen value decision, promptly the pH value by solution determines the solubility product of white lake.Except that aluminum ion precipitated, the silicon in the solution, calcium, magnesium, iron and trivalent chromic ion were also along with co-precipitation together in N-process.
(2) concentration of chromium acid sodium alkaline liquid is unsuitable too high during neutralization reaction, if feed concentration is too high, will generate the utmost point dispersive alumine hydroxide colloid during reaction, makes the strainability variation, and the sexavalent chrome band damage in the aluminium mud increases.But in grog leaching process neutral and alkali liquid, introduced calcium ion; It mainly is present in the alkali solution with the form of solubility chromic acid calcium; Its solubleness descends along with increasing of chromium acid sodium solution concentration; Promptly increase feed concentration and can reduce the yellow ultramarine content in the solution, this not only improves the quality of products and has prevented the fouling of vaporizer hot face.Therefore, neutralization reaction requires chromium acid sodium alkaline liquid will have suitable concentration.
(3) the sodium aluminate hydrolysis reaction is thermo-negative reaction, and elevated temperature is favourable to hydrolysis reaction, and its hydrolysis reaction equation is following:
Figure BSA00000513144100021
Therefore improve the neutralization reaction temperature, help aluminum hydroxide precipitation and form, and can reduce the viscosity of filtrating, strengthen strainability.But the heated and boiled neutral solution can be unfavorable for that other impurity and white lake form common colloidal sol and removes because the violent boiling of feed liquid disperses the white lake flocks in the neutralizing well.Therefore, the neutralization reaction of chromium acid sodium alkaline liquid need be carried out under suitable temperature.
U.S. Pat 3899568 adopts the sodium dichromate mother liquor as neutralizing agent, and this method adopts the sectional operation, can not carry out serialization production; And this method neutralization is for up to 4-12h; Yield poorly, gained aluminium mud is colloid, and the band that does not fundamentally solve aluminium mud decreases problem.The open CN1069711 of one Chinese patent application adopts sodium pyrosulfate to neutralize, and its gained aluminium mud is precipitated as extremely dispersive colloid, and the strainability difference of aluminium mud is washed with being difficult to, and its sexavalent chrome band decreases high.
Therefore, in the chromium acid sodium alkaline liquid and removal of impurities, need a kind of aluminium mud strainability good, the sexavalent chrome band decreases low, but and quantity-produced method.
Summary of the invention
In view of above-mentioned prior art situation, the present inventor has carried out research extensively and profoundly with the removal of impurities field in chromium acid sodium alkaline liquid, in the hope of finding that a kind of aluminium mud strainability is good, the sexavalent chrome band decreases low continuation method.The result finds, by means of the adding of the neutralization reactor that has riser through concentration, pH value, stir speed (S.S.) and the temperature of reaction and the crystal seed of control reaction solution, can realize aforementioned purpose.The inventor just is being based on above-mentioned discovery and is accomplishing the present invention.
Therefore, the purpose of this invention is to provide a kind of chromium acid sodium alkaline liquid continuously in the method for removal of impurities.In the method; In be reflected in the neutralization reactor that has riser and carry out with removal of impurities; Be able to carry out continuously with removal of impurities during this makes, in addition, through in the control of concentration, pH value and the stir speed (S.S.) and the temperature of reaction of reaction solution and add crystal seed; Impurity such as the silicon in the chromium acid sodium alkaline liquid, aluminium, calcium, magnesium, iron, trivalent chromium are separated out with sedimentary form, white lake is transformed into is easy to filtering gipsite (Al 2O 33H 2O), fundamentally solved the problem that aluminium mud deposition is extremely disperseed and is difficult to filter and washs, made aluminium mud deposit seeds thick, settling velocity is fast, and strainability is good, is easy to washing, and the sexavalent chrome band that has reduced in the aluminium mud decreases, and has improved the quality of Sodium chromate-51Cr neutral solution.
The technical scheme of realization the object of the invention can be summarized as follows:
1, a kind of chromium acid sodium alkaline liquid continuously in and the method for removal of impurities, comprise the steps:
The neutral aqueous solution that (1) will contain Sodium chromate-51Cr adds in the neutralization reactor with optional crystal seed;
(2) in neutralization reactor, add continuously chromium acid sodium alkaline liquid and the neutralizing agent that obtains by chromite baked for producing Sodium chromate-51Cr, make that reaction solution is with Na in the neutralization reactor 2Cr 2O 72H 2The concentration of O meter is 100-600gL -1And at 20-750r/min, the mixing speed of preferred 200-500r/min descends and in the presence of crystal seed, reacts, and wherein said neutralizing agent is a carbonic acid gas; The pH value of the interior feed liquid of neutralization reactor this moment is 9.55-9.65; Be preferably 9.58-9.62, and temperature of reaction is 116-125 ℃, is preferably 118-122 ℃; And
(3) feed liquid in neutralization reactor is derived continuously solid-liquid separation, the Sodium chromate-51Cr neutral solution that obtains purifying through the riser that is positioned at this neutralization reactor top.
2, according to the 1st described method, wherein said neutralizing agent for produce by Sodium chromate-51Cr produce in the sodium dichromate process contain chromic acid wastewater, acidizing fluid, acidizing fluid, sodium dichromate mother liquor in advance, sodium dichromate aqueous solutio; Mineral acid; Or any mixture of previous neutralizers, the pH value of the interior feed liquid of neutralization reactor this moment is 6.50-9.70, is preferably 8.50-9.50; And temperature of reaction is 40-105 ℃, and preferred temperature is 50-100 ℃.
3. according to the 1st or 2 described method, wherein carbonic acid gas is the gas use of the volume of 1-100% with the gas concentration lwevel, and mineral acid is a sulfuric acid, and/or chromate waste water, preparatory acidizing fluid, acidizing fluid and sodium dichromate mother liquor are with Na 2Cr 2O 72H 2The concentration of O meter is 100-1500gL -1, and/or sodium dichromate aqueous solutio is with Na 2Cr 2O 72H 2The concentration of O meter is 100-1800gL -1, preferred 200-1000gL -1
4. according to each described method in the 1-3 item, wherein neutral aqueous solution that contains Sodium chromate-51Cr in the step (1) and the chromium acid sodium alkaline liquid in the step (2) are independently of one another with Na 2Cr 2O 72H 2The concentration of O meter is 100-600gL -1, be preferably 200-400gL -1
5. according to each described method in the 1-4 item, wherein crystal seed is material or its mixture of white lake or main aluminium hydroxide.
6. according to each described method in the 1-5 item, wherein the addition of crystal seed is with Al (OH) 3Count the 0.5-10 weight % of reduction of feed volume in the middle neutralization reactor of step (2).
7. according to each described method in the 1-6 item, wherein adopt 40-80 ℃ the middle aluminium mud that obtains that separates of hot wash step (3).
8. according to each described method in the 1-7 item; Wherein neutralization reactor is vertical reactor drum, comprises the bottom that is positioned at this neutralization reactor bottom and is positioned at the vertical top of this neutralization reactor, the cylindrical shell between bottom and top; Bottom, top and cylindrical shell surround the reaction compartment of neutralization reactor jointly; Have one or more opening for feeds at the top and/or on the top of cylindrical shell, on the top of cylindrical shell, preferably at the offside of opening for feed; Have one or more (for example 1-5) riser, and along the whisking appliance of the axial setting of cylindrical shell.
9. according to the 8th described method; Wherein apart from the nearest riser in top and top at a distance of 200-800mm; And/or under the situation that a plurality of risers along the reactor drum axial arranging (12a-12c) arranged, adjacent riser is 50-300mm along the axial spacing of reactor drum.
10. according to the 8th or 9 described method; Wherein whisking appliance comprises two-layer stirring rake up and down along top to the bottom direction of vertical reactor drum, and the upper strata stirring rake is the wide leaf stirring rake of aerofoil profile axial flow, and lower floor's stirring rake is an aerofoil profile axial flow narrow leaf stirring rake; The upper strata stirring rake has bigger expanded area ratio than lower floor's stirring rake; Preferably, the expanded area ratio of upper strata stirring rake is 1.5-3.0, and the expanded area ratio of lower floor's stirring rake is 0.5-0.8.
Description of drawings
Fig. 1 (a) is the front view synoptic diagram of the used neutralization reactor of the inventive method.
Fig. 1 (b) is the vertical view synoptic diagram of the used neutralization reactor of the inventive method.
Fig. 2 is the blade stereographic map of the wide leaf stirring rake of upper strata aerofoil profile axial flow.
Fig. 3 is the blade stereographic map of lower floor's aerofoil profile axial flow narrow leaf stirring rake.
Reference numerals list
11 neutralization reactors
The 12a-12c riser
13 bottoms
14 tops
15 cylindrical shells
16 opening for feeds
17 whisking appliances
18 upper strata stirring rakes
19 lower floor's stirring rakes
20 guide shells
21 heating coils
22 on-line monitoring holes
23 manholes
The 101a-101d feed port
The 102a-102b vision slit
103 manholes
104a-104b on-line monitoring hole
Embodiment
According to the present invention, provide a kind of chromium acid sodium alkaline liquid continuously in the method for removal of impurities, comprise the steps:
The neutral aqueous solution that (1) will contain Sodium chromate-51Cr adds in the neutralization reactor with optional crystal seed;
(2) in neutralization reactor, add continuously chromium acid sodium alkaline liquid and the neutralizing agent that obtains by chromite baked for producing Sodium chromate-51Cr, make that reaction solution is with Na in the neutralization reactor 2Cr 2O 72H 2The concentration of O meter is 100-600gL -1And at 20-750r/min, the mixing speed of preferred 200-500r/min descends and in the presence of crystal seed, reacts, and wherein said neutralizing agent is a carbonic acid gas; The pH value of the interior feed liquid of neutralization reactor this moment is 9.55-9.65; Be preferably 9.58-9.62, and temperature of reaction is 116-125 ℃, is preferably 118-122 ℃; Perhaps said neutralizing agent for produce by Sodium chromate-51Cr produce in the sodium dichromate process contain chromic acid wastewater, acidizing fluid, acidizing fluid, sodium dichromate mother liquor in advance; Sodium dichromate aqueous solutio, mineral acid, or any mixture of previous neutralizers; The pH value of the interior feed liquid of neutralization reactor this moment is 6.50-9.70; Be preferably 8.50-9.50, and temperature of reaction is 40-105 ℃, preferred temperature is 50-100 ℃; And
(3) feed liquid in neutralization reactor is derived continuously solid-liquid separation, the Sodium chromate-51Cr neutral solution that obtains purifying through the riser that is positioned at this neutralization reactor top.
In the methods of the invention,, need in neutralization reactor, to add bed material earlier, promptly carry out step (1) in order to start reaction.This bed material comprises the neutral aqueous solution that contains Sodium chromate-51Cr.As this neutral aqueous solution; Both can use the Sodium chromate-51Cr aqueous solution; The aqueous solution that for example is made into by Sodium chromate-51Cr and water, also can use chromium acid sodium alkaline liquid through in removal of impurities after the Sodium chromate-51Cr neutral solution that obtains, the Sodium chromate-51Cr neutral solution of the purification that for example obtains through the inventive method.For make feed liquid in the neutralization reactor with required with Na 2Cr 2O 72H 2The concentration of O meter is 100-600gL -1, preferred 200-400gL -1React, preferably this neutral aqueous solution that contains Sodium chromate-51Cr is with 100-600gL -1Concentration, preferred 200-400gL -1Concentration use, press Na 2Cr 2O 72H 2The O meter.Except the neutral aqueous solution that contains Sodium chromate-51Cr, bed material also randomly comprises crystal seed, and preferred bed material comprises crystal seed, and the purpose of this crystal seed is to promote to be easy to filtering sedimentary formation, especially gipsite (Al 2O 33H 2O) formation.
Material or its mixture that in the present invention, can use white lake or main aluminium hydroxide are as crystal seed.As the material of main aluminium hydroxide, for example can be aluminium mud, especially the aluminium mud that obtains with removal of impurities through during chromium acid sodium alkaline liquid is continuous through obtaining with method of purification among the present invention.Crystal seed also can be in step (2) just adds before reaction solution reacts, and for example before or after adding chromium acid sodium alkaline liquid and/or neutralizing agent, added, and added in perhaps when adding chromium acid sodium alkaline liquid and/or neutralizing agent.No matter when add, the addition of crystal seed should advantageously make with Al (OH) 3Count the 0.5-10 weight % of reduction of feed volume in the middle neutralization reactor of step (2).The addition of bed material is generally when carrying out neutralization reaction in the step (2) the 10-30 weight % of total reduction of feed volume in the reactor drum, preferred 15-25 weight %, for example 20 weight %.
Preferably, bed material is heated in the later step (2) temperature that feed liquid in the neutralization reactor is carried out neutralization reaction, promptly when use carbonic acid gas during as neutralizing agent; Bed material is heated to 116-125 ℃; Preferred 118-122 ℃, and when use by Sodium chromate-51Cr produce produce in the sodium dichromate process contain chromic acid wastewater, acidizing fluid, acidizing fluid, sodium dichromate mother liquor in advance, sodium dichromate aqueous solutio; Mineral acid; Or any mixture of previous neutralizers is heated to 40-105 ℃ with bed material during as neutralizing agent, preferred 50-100 ℃.
Be appreciated that when neutralization method was carried out continuously, the interpolation of bed material no longer was necessary after reaction starts.Certainly, if when the amount of crystal seed is not enough, can replenish the crystal seed amount.
Subsequently, in the step (2) of the inventive method, chromium acid sodium alkaline liquid is incorporated in the neutralization reactor continuously.In the methods of the invention, treat in the feed liquid of removal of impurities be the chromium acid sodium alkaline liquid that chromite baked for producing Sodium chromate-51Cr obtains.This chromium acid sodium alkaline liquid both can obtain through calcium roasting and leaching are subsequently arranged, and also can obtain through calcium-free roasting and leaching subsequently.In this chromium acid sodium alkaline liquid, except Sodium chromate-51Cr, also can there be impurity such as sodium aluminate, free alkali, water glass, calcium, magnesium, iron and trivalent chromium usually.In order to realize the object of the invention, the introducing of chromium acid sodium alkaline liquid should make that reaction solution is with Na in the neutralization reactor 2Cr 2O 72H 2The concentration of O meter is 100-600gL -1, be preferably 200-400gL -1This for example can control through the concentration of control chromium acid sodium alkaline liquid.Preferably, the concentration of chromium acid sodium alkaline liquid to be introduced is with Na 2Cr 2O 72H 2O counts 100-600gL -1, be preferably 200-400gL -1, this neutral aqueous solution that contains Sodium chromate-51Cr that especially in step (1), adds is also with 100-600gL -1, preferred 200-400gL -1Concentration add fashionable, with Na 2Cr 2O 72H 2The O meter.
For in and chromium acid sodium alkaline liquid, need to add neutralizing agent, also claim souring agent, reduce to required value with pH with this alkali solution.In order to form the good deposition of filterableness required for the present invention, according to the present invention, the neutralization reaction of neutralizing agent and chromium acid sodium alkaline liquid must be carried out under specific reactions temperature, pH value and stir speed (S.S.).
For avoiding in the neutralization reactor local reaction too fierce, thereby form white lake or siliceous colloid, make aluminium mud be difficult for filtering and washing, and even in order to ensure discharging, and stir speed (S.S.) is generally 20-750r/min, preferred 200-500r/min.
As neutralizing agent, can use carbonic acid gas, this moment, the addition of carbonic acid gas should make that the pH value of feed liquid is 9.55-9.65 in the neutralization reactor, was preferably 9.58-6.62, and temperature of reaction is 116-125 ℃, was preferably 118-122 ℃.Carbonic acid gas can add with gas form, preferably is that the gas of 1-100 volume % adds with the concentration of carbon dioxide.To this, carbonic acid gas can adopt industrial carbon dioxide and Air mixing gas, or Industrial Stoves tail gas, like limestone kiln tail gas, cement kiln tail gas etc.
Except carbonic acid gas, as neutralizing agent, can also use by Sodium chromate-51Cr produce produce in the sodium dichromate process contain chromic acid wastewater, acidizing fluid, acidizing fluid, sodium dichromate mother liquor in advance; Sodium dichromate aqueous solutio, mineral acid, any mixture of previous neutralizers; At this moment, the pH value of feed liquid is 6.50-9.70 in the neutralization reactor, is preferably 8.50-9.50; And temperature of reaction is 40-105 ℃, and preferred temperature is 50-100 ℃.
Produce the chromic acid wastewater that contains that produces in the sodium dichromate process by Sodium chromate-51Cr and refer to the Cr that contains that produces in the sodium dichromate production process 2O 7 2-Ionic waste water; Produce the preparatory acidizing fluid that produces in the sodium dichromate process by Sodium chromate-51Cr and be meant that the Sodium chromate-51Cr neutral solution uses sodium pyrosulfate or mineral acid to carry out gained solution after the acidifying; Producing the acidizing fluid that produces in the sodium dichromate process by Sodium chromate-51Cr refers to preparatory acidizing fluid is evaporated and carries out after-souring gained solution with sulfuric acid; Produce the sodium dichromate mother liquor that produces in the sodium dichromate process by Sodium chromate-51Cr and refer to the solution that after isolating crystal, obtains in the sodium dichromate Crystallization Procedure.
As mineral acid, advantageously use sulfuric acid, for example the vitriol oil.As said chromate waste water, preparatory acidizing fluid, acidizing fluid and sodium dichromate mother liquor, preferably they are independently of one another with 100-1500gL -1Concentration use, with Na 2Cr 2O 72H 2The O meter.Sodium dichromate aqueous solutio is preferably with 100-1800gL -1, preferred 200-1000gL -1Concentration use, with Na 2Cr 2O 72H 2The O meter.
In step (2), chromium acid sodium alkaline liquid and neutralizing agent with removal of impurities in treating can add together, also can separately add, preferred separately adding.
After neutralization reaction, the reaction feed liquid is derived through the riser that is positioned at neutralization reactor top continuously, solid-liquid separation, the Sodium chromate-51Cr neutral solution that obtains purifying, and obtain aluminium mud simultaneously as by product.Preferably, with the washing of aluminium mud, gained washing lotion and Sodium chromate-51Cr neutral solution are merged.The separation here adopts the solid-liquid separation means to carry out usually, for example carries out through filtration.The aluminium mud of separating preferably adopts 40-80 ℃ hot wash.After the aluminium mud drying, can be as the crystal seed of the inventive method.
In order to realize the serialization production of the inventive method simply, adopted a kind of neutralization reactor that has riser.
In a preferred embodiment of the inventive method, used neutralization reactor is shown in Fig. 1 a and Fig. 1 b.This neutralization reactor 11 is a vertical reactor drum; Comprise the bottom 13 that is positioned at this neutralization reactor bottom and be positioned at the vertical top 14 of this neutralization reactor; Cylindrical shell 15 between bottom and top, bottom, top and cylindrical shell surround the reaction compartment of neutralization reactor jointly, have one or more opening for feeds 16 at the top and/or on the top of cylindrical shell; Have one or more riser 12a-12c on the top of cylindrical shell, and along the whisking appliance 17 of the axial setting of cylindrical shell 15.
Riser 12a-12c is positioned at the top of reactor drum 11 or cylindrical shell 15, derives will carry out neutralization reaction reaction mixture afterwards, carries out solid-liquid separation.In addition, this set mode of riser makes the loss can avoid crystal seed to a certain extent, can carry out continuous neutralization operation and need not add crystal seed, or not need to add continually crystal seed.
Have under a plurality of situations at riser, these risers also can be arranged along the reactor drum circumferential direction usually along the reactor drum axial arranging, perhaps have this two kinds of arrangement modes simultaneously.Riser is regulated according to inlet amount, perhaps opens one or open a plurality ofly, even opens all risers.Can also select specifically to open which or which overfall based on the liquid level of feed liquid in the reactor.
Be appreciated that riser 12a-12c is preferably placed at the place away from opening for feed 16, is preferably placed at the offside of opening for feed 16 in order to make the neutralization reaction mixture react fully.Riser can have one or more, for example 1-5 riser, preferably 1-3 riser.Advantageously, apart from the nearest riser in top 14 and top 14 at a distance of 200-800mm; Under the situation that a plurality of riser 12a-12c are arranged, if along the reactor drum axial arranging, then adjacent riser is 50-300mm along the axial spacing of reactor drum also advantageously.
Opening for feed 16 also can have one or more, and preferably at least two, for example four, to help the adding that separates of chromium acid sodium alkaline liquid and materials such as neutralizing agent.Under the situation of a plurality of opening for feeds, opening for feed preferably distributes along circumference equably.For example under the situation with four opening for feeds, shown in Fig. 1 (b), the distribution of four opening for feed 101a-101d makes the center of circle separately be positioned on the same circumference, is diagonal lines and distributes, and makes that adjacent opening for feed angle is 90 °., chromium acid sodium alkaline liquid and neutralizing agent react again after being mixed as much as possible; Have under the situation of 2 opening for feeds of surpassing; For example under the situation of 4 opening for feeds, preferred chromic acid soda property liquid and neutralizing agent add respectively from farthest two opening for feed 101a and 101c (perhaps 101b and 101d) apart.Advantageously, the bottom of opening for feed 101a-101d connects the feed liquid sparger.The hole that this feed liquid sparger has a plurality of equally distributed feed liquid to pass through, the aperture in this hole is generally 0.5-50mm, and percentage of open area is 5-75%.
Except above-mentioned parts, be appreciated that the parts that neutralization reactor 11 also has conventional flow reactor and possessed, this comprises the device of realizing the feed liquid heating, this comprises the heating coil 21 that is positioned at reactor drum external heated cover and/or is positioned at inside reactor.In order to realize on-line monitoring hole 22, the 104a-104b of on-line monitoring, with for TM and pH meter etc. are set.The signal feedback that monitoring is obtained is given dcs (DCS), and system is according to monitoring data automatically adjust inlet amount and temperature.The on-line monitoring hole is arranged on the top of reactor drum usually.In order to realize the people getting into the operation of carrying out in the reactor drum, for example maintenance, neutralization reactor 11 also is provided with manhole 23,103, and this is arranged on the top of reactor drum usually.In addition, for the situation of feed liquid in the observing response device, reactor drum also comprises one or more vision slit 102a-102b usually.Vision slit is arranged on the top of reactor drum usually.When feed port, on-line monitoring hole, vision slit and manhole were the top that all is arranged on reactor drum, they separately distributed separately at an angle, for example with angle distribution shown in Fig. 1 (b).In a preferred embodiment of the inventive method; Neutralization reactor 11 also comprises guide shell 20, and the axial velocity profile that this setting is stirred neutralization reactor is more even, has not only eliminated short circuit phenomenon but also help to eliminate the stirring dead angle; Suppressed the expansion of circumferential motion simultaneously; Increase less turbulence, under identical watt consumption, produced bigger circular flow, can improve the homogeneity of feed concentration, temperature, pH value etc. in the neutralization reactor effectively.
In particularly preferred embodiment of the inventive method; Whisking appliance 17 comprises two-layer stirring rake up and down along top to the bottom direction of vertical reactor drum; Upper strata stirring rake 18 is the wide leaf stirring rake of aerofoil profile axial flow, and lower floor's stirring rake 19 is an aerofoil profile axial flow narrow leaf stirring rake.At this moment, upper strata stirring rake 18 has higher expanded area ratio than lower floor stirring rake 19.The expanded area ratio of upper strata stirring rake 18 is generally 1.5-3.0, and the expanded area ratio of lower floor's stirring rake 19 is generally 0.5-0.8.Expanded area ratio is the approximate area sum afterwards and the ratio of stirring rake diameter circle area of flattening of each blade of stirring rake.As the wide leaf stirring rake of aerofoil profile axial flow, it can have preferred 6 high expanded area ratio blades, and central authorities are wheel hub, and blade is connected by floor with wheel hub, through wheel hub blade is installed in the rotating shaft.The wide leaf stirring rake of aerofoil profile axial flow is as shown in Figure 2.Equally, as aerofoil profile axial flow narrow leaf stirring rake, it can have preferred 6 low expanded area ratio blades, and central authorities are wheel hub, and blade is connected by floor with wheel hub, through wheel hub blade is installed in the rotating shaft.Aerofoil profile axial flow narrow leaf stirring rake is as shown in Figure 3.
The present invention adopts the combination of two kinds of dissimilar blades, gives full play to special performance separately, makes that the mixing-dispersing property of each phase system significantly improves in the reactor drum.Upper strata whisking appliance 18 adopts the wide leaf stirring rake of aerofoil profile axial flows, and this oar power is lower and circulation ability is strong, has dispersive ability preferably, to reach the purpose of homogeneous material.Lower floor's stirring rake 19 employing good cycle, the aerofoil profile axial flow narrow leaf stirring rake that power is low suspend the end of to guarantee particle, and the cooperation utilization of two kinds of blades makes the interior feed liquid of reactor drum become homogeneous phase to distribute.The mixing uniformity that combination provided of this two kinds of different expanded area ratio blades helps forming the aluminium mud deposition that filterableness is improved.
The inventive method adopts the mode of one-part form neutralization, operate continuously; Impurity such as the silicon in the chromium acid sodium alkaline liquid, aluminium, calcium, magnesium, iron, trivalent chromium have been removed; The aluminium mud strainability that obtains is good, and the sexavalent chrome band decreases low, and the sexavalent chrome band of aluminium mud decreases (with Na in industrial production 2Cr 2O 72H 2O meter) can reduce to below 0.5%, thereby reduce the quantity discharged of aluminium mud, reduce production cost and effectively raised throughput.
Embodiment
Following examples are used to explain the present invention, but are not used for limiting scope of the present invention.
Embodiment 1
1. to 20L with Na 2Cr 2O 72H 2The concentration of O meter is 295gL -1The Sodium chromate-51Cr neutral solution in add the 700g industrial aluminium hydroxide as crystal seed, process bed material;
2. the opening for feed of bed material via neutralization reactor added in the neutralization reactor, heating makes the bed material temperature remain 120 ℃;
3. will be with Na 2Cr 2O 72H 2The concentration of O meter is 287gL -1And with Na 2CO 3The total alkalinity of meter is 75gL -1The chromium acid sodium alkaline liquid that obtains by chromite baked for producing Sodium chromate-51Cr and the gas concentration carbon dioxide gas mixture that is 18 volume % (this gaseous mixture through with obtaining in the carbonic acid gas entrained air) separately add continuously and contain in the neutralization reactor of bed material; Control the interpolation speed of the two; Make the pH value of feed liquid in the neutralization reactor be 9.6 and the level of reduction of feed volume remain basically stable with the riser that is positioned at reactor shell top, and be that 120 ℃ and mixing speed are to react under the condition of 400r/min in temperature of reaction.Simultaneously, feed liquid shifts out from riser, filters, and filtration velocity is fast, and the Sodium chromate-51Cr neutral solution that obtains purifying is filtrated and aluminium mud, and filters the aluminium mud that obtains with 40 ℃ hot wash, and the Sodium chromate-51Cr neutral solution filtrating that washings and front obtain merges; And
4. the Sodium chromate-51Cr neutral solution filtrating (not containing aluminium mud washings) of gained purification and the aluminium mud after the washing are measured, the result is: with Na 2Cr 2O 72H 2It is 0.18 weight % that the aluminium mud sexavalent chrome band of O meter decreases; Al in the Sodium chromate-51Cr neutral solution filtrating of purifying 3+Content is 0.26mgL -1Ca 2+Content is 4.54ppm, Fe 3+Content is 0.74ppm, Mg 2+Content is 1.32ppm, Cr 3+Content is 6.36ppm; X-ray diffraction is the result show, contains the gipsite (Al of 72 weight % in the aluminium mud 2O 33H 2O).
Embodiment 2
1. to 2L with Na 2Cr 2O 72H 2The concentration of O meter is 285gL -1The Sodium chromate-51Cr neutral solution in add the 65g industrial aluminium hydroxide as crystal seed, process bed material;
2. the opening for feed of bed material via neutralization reactor added in the neutralization reactor, heating makes the bed material temperature remain 100 ℃;
3. will be with Na 2Cr 2O 72H 2The concentration of O meter is 315gL -1And with Na 2CO 3The total alkalinity of meter is 60gL -1The chromium acid sodium alkaline liquid that obtains by chromite baked for producing Sodium chromate-51Cr and concentration with Na 2Cr 2O 72H 2O counts 320gL -1And acid number is with H 2SO 4Count 82gL -1Preparatory acidizing fluid separately add continuously and contain in the neutralization reactor of bed material; The interpolation speed of two kinds of feed liquids of control; Make the pH value of feed liquid in the neutralization reactor be 9.2 and the level of reduction of feed volume remain basically stable with the riser that is positioned at reactor shell top, and be that 100 ℃ and mixing speed are to react under the condition of 350r/min in temperature of reaction.Simultaneously, feed liquid shifts out from riser, filters, and filtration velocity is fast, and the Sodium chromate-51Cr neutral solution that obtains purifying is filtrated and aluminium mud, and filters the aluminium mud that obtains with 60 ℃ hot wash, and the Sodium chromate-51Cr neutral solution filtrating that washings and front obtain merges; And
4. the Sodium chromate-51Cr neutral solution filtrating (not containing aluminium mud washings) of gained purification and the aluminium mud after the washing are measured, the result is: with Na 2Cr 2O 72H 2It is 0.31 weight % that the aluminium mud sexavalent chrome band of O meter decreases; Al in the Sodium chromate-51Cr neutral solution filtrating of purifying 3+Content is 0.47mgL -1, Ca 2+Content is 4.31ppm, Fe 3+Content is 0.71ppm, Mg 2+Content is 0.91ppm, Cr 3+Content is 9.48ppm; X-ray diffraction is the result show, contains the gipsite (Al of 70 weight % in the aluminium mud 2O 33H 2O).
Embodiment 3
1. to 15L with Na 2Cr 2O 72H 2The concentration of O meter is 462gL -1The Sodium chromate-51Cr neutral solution in add 280g according to embodiment aluminium mud 1 preparation and oven dry as crystal seed, process bed material;
2. the opening for feed of bed material via neutralization reactor added in the neutralization reactor, heating makes the bed material temperature remain 95 ℃;
3. will be with Na 2Cr 2O 72H 2The concentration of O meter is 368gL -1And with Na 2CO 3The total alkalinity of meter is 88gL -1The chromium acid sodium alkaline liquid that obtains by chromite baked for producing Sodium chromate-51Cr and the vitriol oil separately add continuously and contain in the neutralization reactor of bed material; The interpolation speed of two kinds of feed liquids of control; Make the pH value of feed liquid in the neutralization reactor be 8.8 and the level of reduction of feed volume remain basically stable with the riser that is positioned at reactor shell top, and be that 95 ℃ and mixing speed are to react under the condition of 480r/min in temperature of reaction.Simultaneously, feed liquid shifts out from riser, filters, and filtration velocity is fast, obtains Sodium chromate-51Cr neutral solution filtrating and aluminium mud, and filters the aluminium mud that obtains with 80 ℃ hot wash, and the Sodium chromate-51Cr neutral solution filtrating that washings and front obtain merges; And
4. the Sodium chromate-51Cr neutral solution filtrating (not containing aluminium mud washings) of gained purification and the aluminium mud after the washing are measured, the result is: with Na 2Cr 2O 72H 2It is 0.41 weight % that the aluminium mud sexavalent chrome band of O meter decreases; Al in the Sodium chromate-51Cr neutral solution filtrating of purifying 3+Content is 1.29mgL -1, Ca 2+Content is 6.24ppm, Fe 3+Content is 0.87ppm, Mg 2+Content is 0.74ppm, Cr 3+Content is 10.23ppm; X-ray diffraction is the result show, contains the gipsite (Al of 65 weight % in the aluminium mud 2O 33H 2O).
Embodiment 4
1. to 5L with Na 2Cr 2O 72H 2The concentration of O meter is 318gL -1The Sodium chromate-51Cr neutral solution in add the 175g industrial aluminium hydroxide as crystal seed, process bed material;
2. the opening for feed of bed material via neutralization reactor added in the neutralization reactor, heating makes the bed material temperature remain 55 ℃;
3. will be with Na 2Cr 2O 72H 2The concentration of O meter is 550gL -1And with Na 2CO 3The total alkalinity of meter is 96gL -1The chromium acid sodium alkaline liquid that obtains by chromite baked for producing Sodium chromate-51Cr and concentration with Na 2Cr 2O 72H 2O counts 1200gL -1Acidizing fluid separately add continuously and contain in the neutralization reactor of bed material; The interpolation speed of two kinds of feed liquids of control; Make the pH value of feed liquid in the neutralization reactor be 6.8 and the level of reduction of feed volume remain basically stable with the riser that is positioned at reactor shell top, and be that 55 ℃ and mixing speed are to react under the condition of 700r/min in temperature of reaction.Simultaneously, feed liquid shifts out from riser, filters, and filtration velocity is fast, obtains Sodium chromate-51Cr neutral solution filtrating and aluminium mud, and filters the aluminium mud that obtains with 60 ℃ hot wash, and the Sodium chromate-51Cr neutral solution filtrating that washings and front obtain merges; And
4. the Sodium chromate-51Cr neutral solution filtrating (not containing aluminium mud washings) of gained purification and the aluminium mud after the washing are measured, the result is: with Na 2Cr 2O 72H 2It is 0.32 weight % that the aluminium mud sexavalent chrome band of O meter decreases; Al in the Sodium chromate-51Cr neutral solution filtrating of purifying 3+Content is 1.38mgL -1, Ca 2+Content is 5.94ppm, Fe 3+Content is 0.79ppm, Mg 2+Content is 0.94ppm, Cr 3+Content is 9.61ppm; X-ray diffraction is the result show, contains the gipsite (Al of 60 weight % in the aluminium mud 2O 33H 2O).
Embodiment 5
1. to 50L with Na 2Cr 2O 72H 2The concentration of O meter is 345gL -1The Sodium chromate-51Cr neutral solution in add the 1200g industrial aluminium hydroxide as crystal seed, process bed material;
2. the opening for feed of bed material via neutralization reactor added in the neutralization reactor, heating makes the bed material temperature remain 95 ℃;
3. will be with Na 2Cr 2O 72H 2The concentration of O meter is 180gL -1And with Na 2CO 3The total alkalinity of meter is 35gL -1The chromium acid sodium alkaline liquid that obtains by chromite baked for producing Sodium chromate-51Cr and concentration with Na 2Cr 2O 72H 2O counts 120gL -1And acid number is with H 2SO 4Count 65gL -1The chromic acid wastewater that contains separately add continuously and contain in the neutralization reactor of bed material; The interpolation speed of two kinds of feed liquids of control; Make the pH value of feed liquid in the neutralization reactor be 9.4 and the level of reduction of feed volume remain basically stable with the riser that is positioned at reactor shell 15 tops, and be that 95 ℃ and mixing speed are to react under the condition of 50r/min in temperature of reaction.Simultaneously, feed liquid shifts out from riser, filters, and filtration velocity is fast, obtains Sodium chromate-51Cr neutral solution filtrating and aluminium mud, and filters the aluminium mud that obtains with 50 ℃ hot wash, and the Sodium chromate-51Cr neutral solution filtrating that washings and front obtain merges; And
4. the Sodium chromate-51Cr neutral solution filtrating (not containing aluminium mud washings) of gained purification and the aluminium mud after the washing are measured, the result is: with Na 2Cr 2O 72H 2It is 0.22 weight % that the aluminium mud sexavalent chrome band of O meter decreases; Al in the Sodium chromate-51Cr neutral solution filtrating of purifying 3+Content is 0.98mgL -1, Ca 2+Content is 4.25ppm, Fe 3+Content is 0.67ppm, Mg 2+Content is 1.05ppm, Cr 3+Content is 9.54ppm; X-ray diffraction is the result show, contains the gipsite (Al of 56 weight % in the aluminium mud 2O 33H 2O).
Embodiment 6
1. to 15L with Na 2Cr 2O 72H 2The concentration of O meter is 500gL -1The Sodium chromate-51Cr neutral solution in add the 275g industrial aluminium hydroxide as crystal seed, process bed material;
2. the opening for feed of bed material via neutralization reactor added in the neutralization reactor, heating makes the bed material temperature remain 80 ℃;
3. will be with Na 2Cr 2O 72H 2The concentration of O meter is 320gL -1And with Na 2CO 3The total alkalinity of meter is 85gL -1The chromium acid sodium alkaline liquid that obtains by chromite baked for producing Sodium chromate-51Cr and concentration with Na 2Cr 2O 72H 2O counts 1500gL -1The sodium dichromate mother liquor separately add continuously and contain in the neutralization reactor of bed material; The interpolation speed of two kinds of feed liquids of control; Make the pH value of feed liquid in the neutralization reactor be 8.5 and the level of reduction of feed volume remain basically stable with the riser that is positioned at reactor shell top, and be that 80 ℃ and mixing speed are to react under the condition of 280r/min in temperature of reaction.Simultaneously, feed liquid shifts out from riser, filters, and filtration velocity is fast, and the Sodium chromate-51Cr neutral solution that obtains purifying is filtrated and aluminium mud, and filters the aluminium mud that obtains with 70 ℃ hot wash, and the Sodium chromate-51Cr neutral solution filtrating that washings and front obtain merges; And
4. the Sodium chromate-51Cr neutral solution filtrating (not containing aluminium mud washings) of gained purification and the aluminium mud after the washing are measured, the result is: with Na 2Cr 2O 72H 2It is 0.37 weight % that the aluminium mud sexavalent chrome band of O meter decreases; Al in the Sodium chromate-51Cr neutral solution filtrating of purifying 3+Content is 1.08mgL -1, Ca 2+Content is 5.57ppm, Fe 3+Content is 0.69ppm, Mg 2+Content is 0.81ppm, Cr 3+Content is 10.58ppm; X-ray diffraction is the result show, contains the gipsite (Al of 62 weight % in the aluminium mud 2O 33H 2O).
Embodiment 7
1. to 60L with Na 2Cr 2O 72H 2The concentration of O meter is 295gL -1The Sodium chromate-51Cr neutral solution in add the 650g industrial aluminium hydroxide as crystal seed, process bed material;
2. the opening for feed of bed material via neutralization reactor added in the neutralization reactor, heating makes the bed material temperature remain 75 ℃;
3. will be with Na 2Cr 2O 72H 2The concentration of O meter is 300gL -1And with Na 2CO 3The total alkalinity of meter is 80gL -1The chromium acid sodium alkaline liquid that obtains by chromite baked for producing Sodium chromate-51Cr and concentration with Na 2Cr 2O 72H 2O counts 1000gL -1The sodium dichromate aqueous solution separately add continuously and contain in the neutralization reactor of bed material; The interpolation speed of two kinds of feed liquids of control; Make the pH value of feed liquid in the neutralization reactor be 8.5 and the level of reduction of feed volume remain basically stable with the riser that is positioned at reactor shell top, and be that 75 ℃ and mixing speed are to react under the condition of 350r/min in temperature of reaction.Simultaneously, feed liquid shifts out from riser, filters, and filtration velocity is fast, obtains Sodium chromate-51Cr neutral solution filtrating and aluminium mud, and filters the aluminium mud that obtains with 65 ℃ hot wash, and the Sodium chromate-51Cr neutral solution filtrating that washings and front obtain merges; And
4. the Sodium chromate-51Cr neutral solution filtrating (not containing aluminium mud washings) of gained purification and the aluminium mud after the washing are measured, the result is: with Na 2Cr 2O 72H 2It is 0.35 weight % that the aluminium mud sexavalent chrome band of O meter decreases; Al in the Sodium chromate-51Cr neutral solution filtrating of purifying 3+Content is 1.15mgL -1, Ca 2+Content is 4.97ppm, Fe 3+Content is 0.72ppm, Mg 2+Content is 0.95ppm, Cr 3+Content is 9.32ppm; X-ray diffraction is the result show, contains the gipsite (Al of 53 weight % in the aluminium mud 2O 33H 2O).
The comparative example 8
1. to 20L with Na 2Cr 2O 72H 2The concentration of O meter is 295gL -1The Sodium chromate-51Cr neutral solution in add the 700g industrial aluminium hydroxide as crystal seed, process bed material;
2. the opening for feed of bed material via neutralization reactor added in the neutralization reactor, heating makes the bed material temperature remain 120 ℃;
3. will be with Na 2Cr 2O 72H 2The concentration of O meter is 280gL -1And with Na 2CO 3The total alkalinity of meter is 75gL -1The chromium acid sodium alkaline liquid that obtains by chromite baked for producing Sodium chromate-51Cr and the gas concentration carbon dioxide gas mixture that is 25 volume % (this gaseous mixture through with obtaining in the carbonic acid gas entrained air) separately add continuously and contain in the neutralization reactor of bed material; Control the interpolation speed of the two; Make the pH value of feed liquid in the neutralization reactor be 6.0 and the level of reduction of feed volume remain basically stable with the riser that is positioned at reactor shell top, and be that 120 ℃ and mixing speed are to react under the condition of 400r/min in temperature of reaction.Simultaneously, feed liquid shifts out from riser, filters; The Sodium chromate-51Cr neutral solution filtrating and the aluminium mud that obtain purifying, this aluminium mud is colloidal, and filters the aluminium mud that obtains with 60 ℃ hot wash; Aluminium mud after the washing still is colloidal, and the Sodium chromate-51Cr neutral solution filtrating that washings and front obtain merges; And
4. the Sodium chromate-51Cr neutral solution filtrating (not containing aluminium mud washings) of gained purification and the aluminium mud after the washing are measured, the result is: with Na 2Cr 2O 72H 2It is 1.25 weight % that the aluminium mud sexavalent chrome band of O meter decreases; Al in the Sodium chromate-51Cr neutral solution filtrating of purifying 3+Content is 1.86mgL -1, Ca 2+Content is 9.20ppm, Fe 3+Content is 3.96ppm, Mg 2+Content is 5.72ppm, Cr 3+Content is 16.15ppm.
The comparative example 9
1. to 5L with Na 2Cr 2O 72H 2The concentration of O meter is 320gL -1The Sodium chromate-51Cr neutral solution in add the 80g industrial aluminium hydroxide as crystal seed, process bed material;
2. the opening for feed of bed material via neutralization reactor added in the neutralization reactor, heating makes the bed material temperature remain 135 ℃;
3. will be with Na 2Cr 2O 72H 2The concentration of O meter is 350gL -1And with Na 2CO 3The total alkalinity of meter is 70gL -1The chromium acid sodium alkaline liquid that obtains by chromite baked for producing Sodium chromate-51Cr and the vitriol oil separately add continuously and contain in the neutralization reactor of bed material; The interpolation speed of two kinds of feed liquids of control; Make the pH value of feed liquid in the neutralization reactor be 7.0 and the level of reduction of feed volume remain basically stable with the riser that is positioned at reactor shell top, and be that 135 ℃ and mixing speed are to react under the condition of 350r/min in temperature of reaction.Simultaneously, feed liquid shifts out from riser, filters; The Sodium chromate-51Cr neutral solution filtrating and the aluminium mud that obtain purifying, this aluminium mud is colloidal, and filters the aluminium mud that obtains with 60 ℃ hot wash; Aluminium mud after the washing still is colloidal, and the Sodium chromate-51Cr neutral solution filtrating that washings and front obtain merges; And
4. the Sodium chromate-51Cr neutral solution filtrating (not containing aluminium mud washings) of gained purification and the aluminium mud after the washing are measured, the result is: with Na 2Cr 2O 72H 2It is 12.15 weight % that the aluminium mud sexavalent chrome band of O meter decreases; Al in the Sodium chromate-51Cr neutral solution filtrating of purifying 3+Content is 2.63mgL -1, Ca 2+Content is 7.32ppm, Fe 3+Content is 1.90ppm, Mg 2+Content is 1.65ppm, Cr 3+Content is 15.38ppm.
The comparative example 10
1. to 2L with Na 2Cr 2O 72H 2The concentration of O meter is 900gL -1The Sodium chromate-51Cr neutral solution in add the 65g industrial aluminium hydroxide as crystal seed, process bed material;
2. the opening for feed of bed material via neutralization reactor added in the neutralization reactor, heating makes the bed material temperature remain 100 ℃;
3. will be with Na 2Cr 2O 72H 2The concentration of O meter is 675gL -1And with Na 2CO 3The total alkalinity of meter is 85gL -1The chromium acid sodium alkaline liquid that obtains by chromite baked for producing Sodium chromate-51Cr and concentration with Na 2Cr 2O 72H 2O counts 320gL -1And acid number is with H 2SO 4Count 82gL -1Preparatory acidizing fluid separately add continuously and contain in the neutralization reactor of bed material; The interpolation speed of two kinds of feed liquids of control; Make the pH value of feed liquid in the neutralization reactor be 7.2 and the level of reduction of feed volume remain basically stable with the riser that is positioned at reactor shell top, and be that 100 ℃ and mixing speed are to react under the condition of 350r/min in temperature of reaction.Simultaneously, feed liquid shifts out from riser, filters; The Sodium chromate-51Cr neutral solution filtrating and the aluminium mud that obtain purifying, this aluminium mud is colloidal, and filters the aluminium mud that obtains with 60 ℃ hot wash; Aluminium mud after the washing still is colloidal, and the Sodium chromate-51Cr neutral solution filtrating that washings and front obtain merges; And
4. the Sodium chromate-51Cr neutral solution filtrating (not containing aluminium mud washings) of gained purification and the aluminium mud after the washing are measured, the result is: with Na 2Cr 2O 72H 2It is 18.58 weight % that the aluminium mud sexavalent chrome band of O meter decreases; Al in the Sodium chromate-51Cr neutral solution filtrating of purifying 3+Content is 2.21mgL -1, Ca 2+Content is 8.23ppm, Fe 3+Content is 1.15ppm, Mg 2+Content is 1.68ppm, Cr 3+Content is 13.89ppm.
The comparative example 11
1. to 15L with Na2Cr 2O 72H 2The concentration of O meter is 450gL -1The Sodium chromate-51Cr neutral solution in add 280g according to embodiment 1 preparation and oven dry after aluminium mud as crystal seed, process bed material;
2. the opening for feed of bed material via neutralization reactor added in the neutralization reactor, heating makes the bed material temperature remain 95 ℃;
3. will be with Na 2Cr 2O 72H 2The concentration of O meter is 350gL -1And with Na 2CO 3The total alkalinity of meter is 80gL -1The chromium acid sodium alkaline liquid that obtains by chromite baked for producing Sodium chromate-51Cr and the vitriol oil separately add continuously and contain in the neutralization reactor of bed material; The interpolation speed of two kinds of feed liquids of control; Make the pH value of feed liquid in the neutralization reactor be 7.5 and the level of reduction of feed volume remain basically stable with the riser that is positioned at reactor shell top, and be that 95 ℃ and mixing speed are to react under the condition of 10r/min in temperature of reaction.Simultaneously, feed liquid shifts out from riser, filters; The Sodium chromate-51Cr neutral solution filtrating and the aluminium mud that obtain purifying, this aluminium mud is colloidal, and filters the aluminium mud that obtains with 80 ℃ hot wash; Aluminium mud after the washing still is colloidal, and the Sodium chromate-51Cr neutral solution filtrating that washings and front obtain merges; And
4. the Sodium chromate-51Cr neutral solution filtrating (not containing aluminium mud washings) of gained purification and the aluminium mud after the washing are measured, the result is: with Na 2Cr 2O 72H 2It is 17.57 weight % that the aluminium mud sexavalent chrome band of O meter decreases; Al in the Sodium chromate-51Cr neutral solution filtrating of purifying 3+Content is 1.97mgL -1, Ca 2+Content is 8.67ppm, Fe 3+Content is 1.05ppm, Mg 2+Content is 0.91ppm, Cr 3+Content is 10.65ppm.
The comparative example 12
1. measure 15L with Na 2Cr 2O 72H 2The concentration of O meter is 500gL -1The Sodium chromate-51Cr neutral solution as bed material;
2. the opening for feed of bed material via neutralization reactor added in the neutralization reactor, heating makes the bed material temperature remain 80 ℃;
3. will be with Na 2Cr 2O 72H 2The concentration of O meter is 320gL -1And with Na 2CO 3The total alkalinity of meter is 85gL -1The chromium acid sodium alkaline liquid that obtains by chromite baked for producing Sodium chromate-51Cr and concentration with Na 2Cr 2O 72H 2O counts 1500gL -1The sodium dichromate mother liquor separately add continuously and contain in the neutralization reactor of bed material; The interpolation speed of two kinds of feed liquids of control; Make the pH value of feed liquid in the neutralization reactor be 8.5 and the level of reduction of feed volume remain basically stable with the riser that is positioned at reactor shell top, and be that 80 ℃ and mixing speed are to react under the condition of 280r/min in temperature of reaction.Simultaneously, feed liquid shifts out from riser, filters; The Sodium chromate-51Cr neutral solution filtrating and the aluminium mud that obtain purifying, this aluminium mud is colloidal, and filters the aluminium mud that obtains with 70 ℃ hot wash; Aluminium mud after the washing still is colloidal, and the Sodium chromate-51Cr neutral solution filtrating that washings and front obtain merges; And
4. the Sodium chromate-51Cr neutral solution filtrating (not containing aluminium mud washings) of gained purification and the aluminium mud after the washing are measured, the result is: with Na 2Cr 2O 72H 2It is 15.93 weight % that the aluminium mud sexavalent chrome band of O meter decreases; Al in the Sodium chromate-51Cr neutral solution filtrating of purifying 3+Content is 1.92mgL -1, Ca 2+Content is 9.85ppm, Fe 3+Content is 0.98ppm, Mg 2+Content is 1.41ppm, Cr 3+Content is 11.15ppm.

Claims (10)

  1. A chromium acid sodium alkaline liquid continuously in the method for removal of impurities, comprise the steps:
    The neutral aqueous solution that (1) will contain Sodium chromate-51Cr adds in the neutralization reactor (11) with optional crystal seed;
    (2) in neutralization reactor (11), add chromium acid sodium alkaline liquid and the neutralizing agent that obtains by chromite baked for producing Sodium chromate-51Cr continuously, make the middle reaction solution of neutralization reactor (11) with Na 2Cr 2O 72H 2The concentration of O meter is 100-600gL -1And at 20-750r/min, the mixing speed of preferred 200-500r/min descends and in the presence of crystal seed, reacts, and wherein said neutralizing agent is a carbonic acid gas; The pH value of the interior feed liquid of neutralization reactor (11) this moment is 9.55-9.65; Be preferably 9.58-9.62, and temperature of reaction is 116-125 ℃, is preferably 118-122 ℃; And
    (3) will derive solid-liquid separation, the Sodium chromate-51Cr neutral solution that obtains purifying continuously through the riser (12a-12c) that is positioned at this neutralization reactor (11) top in the feed liquid in the neutralization reactor (11).
  2. 2. method according to claim 1, wherein said neutralizing agent for produce by Sodium chromate-51Cr produce in the sodium dichromate process contain chromic acid wastewater, acidizing fluid, acidizing fluid, sodium dichromate mother liquor in advance, sodium dichromate aqueous solutio; Mineral acid; Or any mixture of previous neutralizers, the pH value of the interior feed liquid of neutralization reactor (11) this moment is 6.50-9.70, is preferably 8.50-9.50; And temperature of reaction is 40-105 ℃, and preferred temperature is 50-100 ℃.
  3. 3. method according to claim 1 and 2, wherein carbonic acid gas is the gas use of the volume of 1-100% with the gas concentration lwevel, mineral acid is a sulfuric acid, and/or chromate waste water, preparatory acidizing fluid, acidizing fluid and sodium dichromate mother liquor are with Na 2Cr 2O 72H 2The concentration of O meter is 100-1500gL -1, and/or sodium dichromate aqueous solutio is with Na 2Cr 2O 72H 2The concentration of O meter is 100-1800gL -1, preferred 200-1000gL -1
  4. 4. according to each described method among the claim 1-3, wherein neutral aqueous solution that contains Sodium chromate-51Cr in the step (1) and the chromium acid sodium alkaline liquid in the step (2) are independently of one another with Na 2Cr 2O 72H 2The concentration of O meter is 100-600gL -1, be preferably 200-400gL -1
  5. 5. according to each described method among the claim 1-4, wherein crystal seed is material or its mixture of white lake or main aluminium hydroxide.
  6. 6. according to each described method among the claim 1-5, wherein the addition of crystal seed is with Al (OH) 3Count the 0.5-10 weight % of the middle reduction of feed volume of neutralization reactor (11) in the step (2).
  7. 7. according to each described method among the claim 1-6, wherein adopt 40-80 ℃ the middle aluminium mud that obtains that separates of hot wash step (3).
  8. 8. according to each described method among the claim 1-7; Wherein neutralization reactor (11) is vertical reactor drum, comprises the bottom (13) that is positioned at this neutralization reactor bottom and is positioned at the vertical top of this neutralization reactor (14), the cylindrical shell between bottom and top (15); Bottom, top and cylindrical shell surround the reaction compartment of neutralization reactor jointly; Have one or more opening for feeds (16) at the top and/or on the top of cylindrical shell, on the top of cylindrical shell, preferably at the offside of opening for feed (16); Have one or more (for example 1-5) riser (12a-12c), and along the whisking appliance (17) of the axial setting of cylindrical shell (15).
  9. 9. method according to claim 8; Wherein apart from top (14) nearest riser (12a) and top (14) at a distance of 200-800mm; And/or under the situation that a plurality of risers along the reactor drum axial arranging (12a-12c) arranged, adjacent riser is 50-300mm along the axial spacing of reactor drum.
  10. 10. according to Claim 8 or 9 described methods; Wherein whisking appliance (17) comprises two-layer stirring rake up and down along top to the bottom direction of vertical reactor drum, and upper strata stirring rake (18) is the wide leaf stirring rake of aerofoil profile axial flow, and lower floor's stirring rake (19) is an aerofoil profile axial flow narrow leaf stirring rake; The upper strata stirring rake has bigger expanded area ratio than lower floor's stirring rake; Preferably, the expanded area ratio of upper strata stirring rake 18 is 1.5-3.0, and the expanded area ratio of lower floor's stirring rake 19 is 0.5-0.8.
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CN102910678A (en) * 2012-11-23 2013-02-06 四川省安县银河建化（集团）有限公司 Method for preparing sodium chromate
CN107954475A (en) * 2017-11-13 2018-04-24 陕西省商南县东正化工有限责任公司 A kind of method that chromium acid sodium alkaline liquid continuously neutralizes filtration washing

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