A kind of Bayer process coproduction chemical aluminum oxide production method
Technical field
The present invention relates to technical field of alumina production, produce more particularly to a kind of Bayer process coproduction chemical aluminum oxide
Method, especially Bayer process coproduction boehmite production method or Bayer process co-production of ultrafine method for manufacturing aluminium hydroxide.
Background technique
Chemical aluminum oxide refers to aluminium hydroxide, aluminium oxide and aluminum contained compound in addition to producing aluminium ingot aluminium oxide,
For example including ultrafine aluminium hydroxide and boehmite.By taking boehmite as an example, boehmite is also referred to as false boehmite,
Also known as monohydrate alumina, it is a kind of aluminium hydroxide series chemical product, is thixotropy gel containing aquosity.Boehmite
Space structure be it is netted, crystal microscopic structure it is mutually single spend it is relatively high;Meanwhile also there are stronger peptization and caking property;
In addition to this, it is higher with more specific surface area, and hole holds various features such as larger.It is physical due to boehmite
Matter, most cases can be used as desiccant, catalyst and support material in life, and its derived product then can be wide
General use is in petrochemical industry, nitrogenous fertilizer, environmental protection, medical manufacture and fireproofing technique material.Boehmite is to produce
The important intermediate of activated alumina belongs to a kind of special-alumina.Boehmite heats the γ-Al being transformed into2O3It is common
Make catalyst and its carrier, is a kind of the most widely used catalyst and its support material, accounts for about industrial supported catalyst
The 70% of agent.Mainly there are middle aluminium share Shandong branch company (Shandong Zibo), middle aluminium in the producer of domestic production boehmite at present
Shanxi Aluminium Plant (Shanxi Hejin), the Guizhou Zhong Lv branch company (Guizhou Kweiyang), Wenzhou essence crystal alumina Co., Ltd, total production capacity are
5.5 ten thousand tons/year.And practical domestic boehmite market annual requirement is about 7.5 ten thousand tons or so, it about 2.5 ten thousand tons of notch, can
See boehmite wide market.
The manufacturing method of chemical aluminum oxide is more, and China predominantly relies on Alumina Enterprise production of chemicals mostly at present
Aluminium oxide is to distribute the Bayer process sperm of part from Bayer process sperm to be used for shown in attached drawing 1 such as boehmite product
The process for producing flow chart of boehmite product.The existing technique stream for relying on Alumina Enterprise production boehmite
Cheng Zhong, most of Bayer process sperm enter kind and divide decomposer, produce aluminium ingot aluminium oxide, small part according to Bayer process common process
Bayer process sperm enter carbon divide decomposer carry out carbon decomposition prepare boehmite.Carbon point decomposes the neutralizer used as work
The CO of industry2Gas.Alumina Enterprise is relied on to produce boehmite product, easy to operate, cost is relatively low, and is able to achieve environmental protection
On zero-emission, pollution-free, the product of production is common boehmite product.Boehmite production technology mainly uses low
The technical conditions that temperature, low concentration, quick carbon divide, wherein the boehmite decomposed needs a large amount of water washing, 1 ton of every production is quasi-
Boehmite probably needs 49 tons of water washing.As shown in Figure 1, washing obtains boehmite product in filtration washing slot,
A wash water of the Nk (caustic sodium concentration) in 7~9g/L sends to preparing lime milk;Secondary wash water one in 0.5g/L or so of Nk
Divide and be used to dilute the Bayer process sperm that Bayer process system is come, a part does the laterite washing water of Bayer process system.After carbon point
Filtrated stock is mainly carbon alkali, needs to be re-introduced into Bayer process system after being 20~40g/L with milk of lime causticization to Nk, into Bayer
After method system, vapo(u)rization system is sent to, needing to be evaporated to Nk is 230~250g/L, considerably increases steam consumption for evaporation, increases
Production cost.Equally, when Bayer process co-production of ultrafine aluminium hydroxide, the ultrafine aluminium hydroxide product produced is also required to largely
Water is washed, and a large amount of ultrafine aluminium hydroxide product washing can be generated, and is at present also to enter vapo(u)rization system, is increased evaporation vapour
Consumption, increases production cost, as shown in Figure 2.
For Bayer process system, the ore pulp after high pressure digestion needs sedimentation separation red out after dilution desiliconization slot dilution
Mud, the step for completed in red-mud separation subsider.The overflow of red-mud separation subsider is crude liquid, is refining to obtain by leaf filter
To Bayer process sperm.It is found in production process, the molecular proportion of Bayer process sperm (sodium oxide molybdena and aluminium oxide in molecular proportion ie in solution
Molar ratio) it is often higher than the molecular proportion of stripping slurry, this is because caused by sodium aluminate solution hydrolyzes.Sodium aluminate solution hydrolysis
Product be aluminium hydroxide and sodium hydroxide, aluminium hydroxide enters red mud outlet, and sodium hydroxide is then stayed in Bayer process sperm, made
It is increased at sperm molecular proportion;Aluminium hydroxide into outlet red mud then causes the loss of aluminum hydroxide product.Lower molecular ratio
The sodium aluminate solution hydrolysis of intermediate concentration be inevitable because the degree of supersaturation of solution is high, stability of solution is poor.Hydrolysis
The underflow part for occurring mainly in red-mud separation subsider, after red mud is washed, washing lotion molecular proportion will increase therewith, with this
Washing lotion removes dilution stripping slurry, will raise the molecular proportion of liquid phase.Now in alumina industry, exist to solve sedimenting system
Hydrolysis problem, the molecular proportion of stripping slurry cannot be too low in dissolution step, and to reduce hydrolysis, but stripping slurry molecular proportion is high
Bayer process can be seriously affected again proposes production and cycle efficieny, and it is weary that this contradiction has proposed production at aluminium oxide Bayer process production system
The bottleneck problem of power.
Summary of the invention
The invention mainly solves the technical problem of providing a kind of Bayer process coproduction chemical aluminum oxide production method, chemistry
Product aluminium oxide can be boehmite or ultrafine aluminium hydroxide, and on the one hand the method for the present invention can reduce evaporation energy consumption, separately
On the one hand the cycle efficieny of Bayer process production system can be improved.
In order to solve the above technical problems, the technical solution adopted by the present invention is that: a kind of Bayer process coproduction chemical aluminum oxide
Production method, chemical aluminum oxide are boehmite or ultrafine aluminium hydroxide;
The mistake when chemical aluminum oxide of production is boehmite, after carbon in boehmite production system point is decomposed
It is 20~50g/L that mother liquor milk of lime causticization, which is filtered, to Nk, obtains causticization liquid, send the causticization liquid to red-mud separation settle later
To any position between red mud once washing subsider top in the middle part of slot mud layer, the causticization liquid is with red-mud separation subsider
Red mud underflow enters red mud once washing subsider;
When the chemical aluminum oxide of production is ultrafine aluminium hydroxide, ultrafine aluminium hydroxide product washing is sent to red-mud separation
To any position between red mud once washing subsider top, the ultrafine aluminium hydroxide product washing in the middle part of subsider mud layer
Enter red mud once washing subsider with the red mud underflow of red-mud separation subsider.
Further, the Nk of the ultrafine aluminium hydroxide product washing is 30~70g/L.
Preferably, the causticization liquid is sent to red-mud separation subsider mud layer middle and lower part.Because of the hydrolysis master of sodium aluminate solution
Occur to send the causticization liquid to red-mud separation subsider mud layer middle and lower part in the underflow part of red-mud separation subsider, it can
To improve the molecular proportion of red-mud separation subsider underflow Partial Liquid Phase, hydrolysis is effectively reduced.
Preferably, the ultrafine aluminium hydroxide product washing is sent to red-mud separation subsider mud layer middle and lower part.Again it is because
The ultrafine aluminium hydroxide product is washed in the underflow part that red-mud separation subsider is occurred mainly in for the hydrolysis of sodium aluminate solution
Liquid is sent to red-mud separation subsider mud layer middle and lower part, and the molecular proportion of red-mud separation subsider underflow Partial Liquid Phase can be improved, have
Effect reduces hydrolysis.
Preferably, after the causticization liquid enters red-mud separation subsider, top molecular proportion is formed in red-mud separation subsider
The slurry distribution of 1.3~1.6 sodium aluminate solution crude liquid, lower liquid phase molecular proportion 1.6~2.5.
Preferably, after the ultrafine aluminium hydroxide product washing enters red-mud separation subsider, in red-mud separation subsider
Form the slurry distribution of the sodium aluminate solution crude liquid, lower liquid phase molecular proportion 1.6~2.5 of top molecular proportion 1.3~1.6.
The effect of red-mud separation subsider is that sedimentation separation goes out red mud, the supernatant in red-mud separation subsider, in slot
Overflow sends to decomposition through leaf filter and aluminium hydroxide is precipitated, the dense red mud slurry for unloading cinder notch discharge is bottom to sodium aluminate solution collection vessel
Stream.Red-mud separation subsider internal upper part is sodium aluminate solution crude liquid layer, and lower part is dense comprising red mud and sodium aluminate solution crude liquid
Red mud pulp layer namely mud layer.After the causticization liquid or the ultrafine aluminium hydroxide product washing enter red-mud separation subsider,
The sodium aluminate solution crude liquid layer molecular proportion of red-mud separation subsider internal upper part is 1.3~1.6, and lower part includes red mud and sodium aluminate solution
The molecular proportion of the dense red mud pulp layer liquid phase of liquid crude liquid is 1.6~2.5.
It is further preferred that in red-mud separation subsider, from 1 below red-mud separation subsider top liquid level position to liquid level
The sodium aluminate solution region molecules ratio of rice is 1.3~1.6, from red-mud separation subsider underflow discharge port to along vertical height side
It is 1.6~2.5 to upward 1 meter of slurry region liquid phase molecule ratio.
The lower part red mud layer liquid phase molecule of red-mud separation subsider is than raising namely underflow liquid phase molecule than raising, aluminic acid
Sodium solution hydrolysis is effectively inhibited.
Bayer process coproduction chemical aluminum oxide production method provided by the invention, by causticization liquid or ultrafine aluminium hydroxide product
The red-mud separation subsider that washing lotion is sent into Bayer process production system rushes dilute bottom into the mud layer middle and lower part of red-mud separation subsider
Red mud once washing subsider is reached after stream.So on the one hand, causticization liquid or ultrafine aluminium hydroxide product washing are raw in Bayer process
Production system is digested and assimilated, and is concentrated without devaporation again, has been saved steam consumption for evaporation.On the other hand, causticization liquid or ultra-fine hydrogen-oxygen
Change aluminium product washing and enters the sodium aluminate solution hydrolysis that Bayer process sedimenting system also can be effectively suppressed in red mud once washing subsider.
Red-mud separation subsider underflow attached liquid (sodium aluminate solution in underflow attached liquid, that is, underflow) originally is the medium satiety of lower molecular ratio
And sodium aluminate solution, Gu stability is very poor containing high, temperature is low, aluminium hydroxide is precipitated in easily hydrolysis, and the aluminium hydroxide of precipitation enters
Red mud causes the loss of aluminium hydroxide.It send by ultrafine aluminium hydroxide product washing or causticization liquid to red-mud separation subsider
Before mud layer bottom, the caustic alkali concentration of slurries is 80~180g/L, 30~900g/L of red mud solid content, consolidates in red-mud separation subsider
Body alumina silica ratio 1.0~1.5, Gu containing height, stability is poor.Causticization liquid or ultrafine aluminium hydroxide product washing are sent into Bayer by the present invention
The red-mud separation subsider of method production system, into the mud layer middle and lower part of red-mud separation subsider, so that it may reduce red-mud separation
The degree of supersaturation of subsider underflow attached liquid and contain admittedly, the causticization liquid or ultrafine aluminium hydroxide product washing based on caustic alkali with
Molecular proportion can be improved in red-mud separation subsider mud layer or underflow mixing, effectively inhibits the generation of hydrolysis.Using side of the invention
Method can effectively solve sodium aluminate solution hydrolysis problem, can further decrease the molecule of stripping slurry in dissolution step in this way
Than to improve cycle efficieny.Therefore, it can effectively solve Bayer process production system and propose production bottleneck problem out of strength, to visit
Ear method is energy-saving and raising cycle efficieny finds a desirable route.
Detailed description of the invention
Fig. 1 is existing Alumina Enterprise production boehmite process flow chart;
Fig. 2 is existing Alumina Enterprise production ultrafine aluminium hydroxide process flow chart;
Fig. 3 is that the improved Alumina Enterprise of the present invention produces boehmite process flow chart;
Fig. 4 is that the improved Alumina Enterprise of the present invention produces ultrafine aluminium hydroxide process flow chart.
Specific embodiment
The technical scheme of the invention is described in detail through specific implementation examples.
Embodiment 1
Certain alumina producing enterprise A, is produced according to process flow shown in FIG. 1.Technological parameter is as follows:
Dissolve out slurries: 200m3/ h, Nk 260g/L, α k 1.41, red mud A/S1.21;
Red mud primary wash liquor: Nk 58g/L, α k 1.59,180m3/h;
Dilute desiliconization slot slurries: Nk 165g/L, α k 1.45;
Red-mud separation subsider underflow: Nk 166g/L, α k 1.55;
Abandon red mud: A/S1.25;
Bayer process sperm: α k 1.48.
It improves according to the method for the present invention, as shown in Figure 3, specific improvement is as follows for improved process flow chart:
Filtrated stock after carbon in boehmite production system point is decomposed is 21g/L with milk of lime causticization to Nk, is obtained
To causticization liquid, causticization liquid is sent to the middle and lower part of the mud layer to red-mud separation subsider later, divides at 5 and causticization liquid 40m is added altogether3/
H enters red mud once washing subsider, red mud once washing subsider overflow with the red mud underflow of red-mud separation subsider later
Red mud primary wash liquor enters red-mud separation subsider through diluting desiliconization slot again, and top molecular proportion is formed in red-mud separation subsider
The 1.46 slurry distribution of sodium aluminate solution crude liquid, lower molecules than 1.71;Wherein, causticization liquid is sent to red-mud separation subsider
Mud layer lower part before, in red-mud separation subsider the caustic alkali concentration of slurries be 165g/L, red mud solid content 800g/L, solid aluminium silicon
Than 1.23.
Using improved technique, technological parameter is as follows:
The underflow of red-mud separation subsider: Nk 110g/L, α k 1.71;
Red mud primary wash liquor: Nk 50g/L, α k 1.72;
Dilute desiliconization slot slurries: Nk 164g/L, α k 1.46;
Abandon red mud: A/S1.22;
Bayer process sperm: α k 1.48.
Obviously, from the underflow liquid phase of red-mud separation subsider and red mud primary wash liquor α k and red mud A/S it can be seen that
The α k of former red mud primary wash liquor is 1.59, becomes α k value 1.72 after improved, hence it is evident that is risen, by pure causticity alkali soluble
The intervention of liquid actively improves molecular proportion α k value, increases the stability of solution, avoids passively hydrolyzing the loss for causing aluminium oxide;
The underflow liquid phase of former red-mud separation subsider: Nk 166g/L, α k 1.55 is Nk 110g/L, α k after improvement
The decline of 1.71, Nk values, α k value rise, the diluting effect of decline and the underflow of solution concentration, are the washing and sedimentation of subsequent red mud
Create good condition;
The red mud A/S for dissolving out slurries is 1.21, and it is 1.25 that original, which abandons red mud A/S, and it is 1.22 that red mud A/S is abandoned after improvement, more former
Red mud is abandoned to be decreased obviously, it is close with the red mud alumina silica ratio of dissolution slurries, it further illustrates and actively improves red-mud separation subsider
The molecular proportion α k value of underflow solution, it is suppressed that the hydrolysis of aluminium oxide enters red mud and causes to abandon the raising of red mud A/S in solution.
The above analytic explanation inhibits the hydrolysis of sodium aluminate solution in Bayer process production system after improvement, retrieve hydrolysis damage
It loses, and the underflow of red-mud separation subsider is diluted, improves red-mud settlement detersive efficiency, evaporation evaporates 35 less per hour
Ton water, significantly reduces evaporation energy consumption.
Embodiment 2
Certain alumina producing enterprise B, is produced according to process flow shown in FIG. 1.Technological parameter is as follows:
Dissolve out slurries: 320m3/ h, Nk 280g/L, α k 1.38, red mud A/S1.18;
Red mud primary wash liquor: Nk 61g/L, α k 1.57,300m3/h;
Dilute desiliconization slot slurries: Nk 168g/L, α k 1.42;
Red-mud separation subsider underflow: Nk 165g/L, α k 1.53;
Abandon red mud: A/S1.21;
Bayer process sperm: α k 1.45.
It improves according to the method for the present invention, as shown in Figure 3, specific improvement is as follows for improved process flow chart:
Filtrated stock after carbon in boehmite production system point is decomposed is 50g/L with milk of lime causticization to Nk, is obtained
To causticization liquid, causticization liquid is sent to the mud layer middle and lower part of red-mud separation subsider later, divides at 6 and causticization liquid 60m is added altogether3/ h,
Enter red mud once washing subsider with the red mud underflow of red-mud separation subsider later, red mud once washing subsider overflow is red
Mud primary wash liquor enters red-mud separation subsider through diluting desiliconization slot again, and top molecular proportion is formed in red-mud separation subsider
The 1.49 slurry distribution of sodium aluminate solution crude liquid, lower molecules than 2.21;Wherein, causticization liquid is sent to red-mud separation subsider
Mud layer lower part before, in red-mud separation subsider the caustic alkali concentration of slurries be 167g/L, red mud solid content 750g/L, solid aluminium silicon
Than 1.05.
Using improved technique, technological parameter is as follows:
The underflow of red-mud separation subsider: Nk 120g/L, α k 1.70;
Red mud primary wash liquor: Nk 56g/L, α k 1.72;
Dilute desiliconization slot slurries: Nk 169g/L, α k 1.43;
Abandon red mud: A/S1.19;
Bayer process sperm: α k 1.45.
Similarly, it can be seen that improvement from the underflow liquid phase of red-mud separation subsider and red mud primary wash liquor α k and red mud A/S
Hydrolysising loss, and the bottom of red-mud separation subsider are retrieved in the hydrolysis for inhibiting sodium aluminate solution in Bayer process production system afterwards
Stream pre-dilution improves red-mud settlement detersive efficiency, and evaporation evaporates 52 tons of water less per hour, significantly reduces evaporation energy consumption.
Embodiment 3
Certain alumina producing enterprise C, is produced according to process flow shown in Fig. 2.Parameter is as follows:
Ultrafine aluminium hydroxide washing lotion: Nk 60g/L, α k 2.95,80m3/h;
Dissolve out slurries: 520m3/ h, Nk 280g/L, α k 1.38, red mud A/S1.20;
Red mud primary wash liquor: Nk 61g/L, α k 1.57,300m3/h;
Dilute desiliconization slot slurries: Nk 165g/L, α k 1.40;
Red-mud separation subsider underflow: Nk 165g/L, α k 1.53;
Abandon red mud: A/S1.23;
Bayer process sperm: α k 1.46.
It improves according to the method for the present invention, as shown in Figure 4, specific improvement is as follows for improved process flow chart:
Ultrafine aluminium hydroxide washing lotion in ultrafine aluminium hydroxide production system is sent to the mud layer of red-mud separation subsider
Middle and lower part is divided at 8 and ultrafine aluminium hydroxide washing lotion 80m is added altogether3/ h enters with the red mud underflow of red-mud separation subsider red later
Mud once washing subsider, red mud once washing subsider overflow red mud primary wash liquor enter red-mud separation through diluting desiliconization slot again
Subsider, the sodium aluminate solution crude liquid that top molecular proportion 1.45 is formed in red-mud separation subsider, lower molecules are than 2.11
Slurry distribution;Wherein, ultrafine aluminium hydroxide washing lotion is sent to the mud layer lower part of red-mud separation subsider, red-mud separation subsider
The caustic alkali concentration of middle slurries is 158g/L, red mud solid content 550g/L, solid alumina silica ratio 1.15.
Using improved technique, technological parameter is as follows:
The underflow of red-mud separation subsider: Nk 129g/L, α k 1.71;
Red mud primary wash liquor: Nk 56g/L, α k 1.72;
Dilute desiliconization slot slurries: Nk 166g/L, α k 1.41;
Abandon red mud: A/S1.21;
Bayer process sperm: α k 1.45.
Similarly, it can be seen that improvement from the underflow liquid phase of red-mud separation subsider and red mud primary wash liquor α k and red mud A/S
Hydrolysising loss, and the bottom of red-mud separation subsider are retrieved in the hydrolysis for inhibiting sodium aluminate solution in Bayer process production system afterwards
Stream pre-dilution improves red-mud settlement detersive efficiency, and evaporation water is reduced, and significantly reduces evaporation energy consumption.