CN1056091A

CN1056091A - Producing sand like synthetic cryolite by clay bittern method

Info

Publication number: CN1056091A
Application number: CN 90105451
Authority: CN
Inventors: 唐仲友; 旷昌平; 李月秋; 李映伟; 匡兰秀
Original assignee: 唐仲友
Priority date: 1990-04-28
Filing date: 1990-04-28
Publication date: 1991-11-13

Abstract

The present invention is a kind of novel method of producing sand like synthetic cryolite a---clay bittern method, and it is raw material substitution soda ash and hydrofluoaluminic acid with clay and salt.It generates aluminum trichloride solution with the aluminium in the dilute hydrochloric acid solution leaching clay; At normal temperatures and pressures, salt is added above-mentioned solution and must mix saltwater brine; This mixes saltwater brine and hydrofluoric acid reacts the generation cryolite slurry at normal temperatures and pressures; Slip after filtration, be drying to obtain the sand like synthetic cryolite finished product.This law reacting balance, raw material is easy to get, and its product sand like synthetic cryolite helps the aluminium metallurgy process modification.

Description

Producing sand like synthetic cryolite by clay bittern method

The present invention is a kind of novel method-clay bittern method of producing sand like synthetic cryolite, and the chemical name of sodium aluminum fluoride is a sodium fluoroaluminate, and its molecular formula is Na ₃AlF ₆

Sodium aluminum fluoride has natural cryolite and cryolith, and it is the fusing assistant of aluminium metallurgy, and aluminum smelting industry mainly uses cryolith in the world.The traditional processing technology of cryolith is a soda ash, the hydrofluoaluminic acid method, and reaction formula is as follows:

The gained cryolite slurry after filtration, dry sodium aluminum fluoride finished product, the state quality standard of this product sees Table: (GB4291～84)

F

AL

Na

SiO ₂+Fe ₂O ₃

SO ₄

P ₂O ₅

H ₂O

Grade

Be not less than

Be not more than

Superfine one-level secondary

53 53 53

13 13 13

31 31 31

0.25 0.40 0.50

0.8 1.2 1.5

0.02 0.05 0.05

0.5 0.8 1.3

The weak point of this production technique is that raw materials used aluminium hydroxide and soda ash are at present domestic very in short supply, causes many factories to cause stopping production for want of raw materials, and synthetic hydrofluoaluminic acid reaction is violent, operates waywardly, and the tank boil-overs casualty accident takes place easily; Because whole process of production is carried out under acidic conditions, and temperature is higher, and is serious to equipment corrosion, and there is acid waste residue to produce contaminate environment; The sodium aluminum fluoride particle that this method is produced is superfine, and is unfavorable to aluminium metallurgy; Cost of material is expensive, the cost height.

At the problems referred to above, the present invention proposes a kind of is the novel method-clay bittern method of raw material production sand like synthetic cryolite with clay and alternative aluminium hydroxide and the soda ash in short supply of salt, and this method is produced and is easy to control, and three-waste pollution is lighter, not only cost reduces, and the sodium aluminum fluoride quality improves.

Method of the present invention is with the clay breeze, and salt and hydrofluoric acid are that its reaction formula of raw material synthetic cryolite (sodium fluoroaluminate) is as follows:

Its producing and manufacturing technique is as follows: prepare leaching liquid with hydrochloric acid earlier, leaching liquid heats the back and adds the clay breeze, and leaching aluminium wherein generates aluminum trichloride solution, and this solution gets aluminum trichloride solution through the settlement separate unreacting substance of removing; At normal temperatures and pressures salt is added the mixing saltwater brine of making aluminum chloride and sodium-chlor in the aluminum trichloride solution; Mix the reaction of saltwater brine and hydrofluoric acid at normal temperatures and pressures and generate sodium aluminum fluoride (Na ₃ALF ₆), get cryolite slurry; Then cryolite slurry is filtered, drying makes the sand like synthetic cryolite finished product.

The raw clay breeze can adopt soft clay or flint clay or its AL of bauxitic clay ₂O ₃Content 〉=25%, fineness are more than 80 orders.Salt is that the content (weight percent) of sea salt or edible salt or rock sea hydrofluoric acid is 10～25%, wherein H ₂SiF ₆Content 0.2～0.3%.

Leaching liquid bag hydrochloric acid 8～20%(weight percent), leaching temperature is 40 ℃～95 ℃, and the add-on of clay breeze makes the AL in the clay breeze according to the quantity meter of hydrochloric acid during leaching ₂O ₃It is excessive 20～40% to measure, this moment AL ₂O ₃Leaching rate be 60～80%, adopt AL ₂O ₃Excessive, make the solution after the leaching not be with acidity, help the improvement of the anticorrosion and labor condition of equipment, clay price ratio salt acid value is low simultaneously, can reduce cost.

The preparation of aluminum chloride and salt mixing saltwater brine is 1: 3 ratio preparation in the molecular ratio of AL and Na, and salt is added in the aluminum trichloride solution, and sodium aluminum fluoride to be synthesized is used.

The sodium aluminum fluoride building-up reactions is carried out at normal temperatures and pressures, and its raw material is for mixing saltwater brine and hydrofluoric acid, and its charge ratio is AL: Na: F=1: 3: the 6(molecular ratio), the specification of hydrofluoric acid is HF10～25%, H ₂SiF ₃0.2～0.3%, mix saltwater brine and hydrofluoric acid and add simultaneously in the synthetic groove, edged reaction in limit gets cryolite slurry, and building-up reactions is carried out with discontinuous, but also continous way is carried out.Slip can adopt vacuum filtration, also can adopt press filtration or centrifuging.Then that filter cake is dry under 150～300 ℃ of temperature, drying can adopt air stream drying, also can adopt the direct drying or the indirect heating drying of rotary kiln, gets the sand like synthetic cryolite finished product.Final product quality is through the chemical examination of Hunan Province's nonferrous metal product quality monitoring testing station, and its quality index is as follows:

Composition:

F

AL

Na

SiO ₂+Fe ₂O ₃

SO ₄

P ₂O ₅

H ₂O

Content:

53.46％

13.40％

30.47％

0.36％

＜0.5％

0.0026％

0.20％

This shows that quality product reaches the requirement of GB first grade, and sulfate radical (SO ₄) content reaches select quality.Quality is better than the present domestic sodium aluminum fluoride of producing with soda ash hydrofluoaluminic acid method, and as the aluminium metallurgy fusing assistant, sand like synthetic cryolite more is better than the granular ice spar.

Fig. 1 is the producing sand like synthetic cryolite by clay bittern method process flow sheet.

Producing sand like synthetic cryolite by clay bittern method, its characteristics are to have substituted raw aluminum hydroxide in short supply and soda ash with clay and salt, and this raw material is not only inexpensive, and is available anywhere. And can reduce the cost of ice crystal, and its cost reduces about 20% than traditional fluoaluminic acid method, and economic benefit is aobvious, solved the raw material supply problem, the existing producer that adopts Traditional Method to produce ice crystal all can use this law instead, existing equipment all can utilize and need not increase investment, and is very favourable. This law technique is simple, reacting balance, and whole production process can operate under normal pressure and temperature or not too high temperature conditions, is conducive to the anticorrosion of the improvement of working condition and equipment. The mother liquor reusable edible that produces in the technical process, discharge capacity seldom reduce sewage load, and be favourable to environmental protection. The sand like synthetic cryolite that this law is produced, it is a breakthrough on the ice crystal crystal habit, at present existing technique all can't be produced sand like synthetic cryolite, this law has solved this difficult problem, and use sand like synthetic cryolite to make flux, and be conducive to the aluminium metallurgy process modification, make the primary aluminum cost, and can improve working conditions and environmental condition, be desired in the aluminum smelting technology. Ice crystal is useful as pesticides on agricultural, in the silicate industry for the manufacture of the opalizer of glass and enamel.

Embodiment: (1) leaching: the preparation of leaching liquid: be made into concentration (weight percent) with industrial dilute hydrochloric acid and be the aqueous hydrochloric acid of 10-18%, leaching liquid adds in the groove, be heated to 60-90 ℃, add clay powder then, stirring reaction was mixed 1: 30～2: 30 hours under the normal pressure, and leaching finishes, after special processing, the settlement separate unreacting substance of removing gets aluminum trichloride solution.If in the factory Acid of Hydrofluoric Acid Production technology is arranged, then settled unreacted reactant can be participated in the fluorgypsum.(2) mix the preparation of saltwater brine: in the molecular ratio of Al and Na is 1: 3 ratio, calculates the add-on of salt (NaCl), under normal temperature and pressure constantly stirs salt is added in the aluminum trichloride solution, salt is dissolved and makes the mixing saltwater brine.(3) sodium aluminum fluoride is synthetic: add the part circulating mother liquor earlier in synthetic groove, under normal temperature and pressure constantly stirs, will mix saltwater brine and hydrofluoric acid and be added simultaneously in the synthetic groove by scale tank, limit edged reaction, reinforced finishing, reaction finishes, get cryolite slurry, synthesize and carry out with discontinuous manner.(4) cryolite slurry vacuum filtration, filter cake washs with clear water, and the hydrochloric acid that has the sodium aluminum fluoride building-up reactions to be generated in the filtrate returns as leaching liquid and recycles, and need not add hydrochloric acid, and the water content of filter flask is below 25%.(5) filter cake is under 150 ℃～300 ℃ temperature, with warm air drying to water content below 1%, promptly get the sand like synthetic cryolite finished product.

Claims

1, a kind of novel method-clay bittern method of producing sand like synthetic cryolite, the chemical name of sodium aluminum fluoride is a sodium fluoroaluminate, molecular formula is Na ₃AF ₆, it is characterized in that:

(1) raw material is clay breeze, salt and hydrofluoric acid;

(2) prepare leaching liquid with hydrochloric acid earlier, the heating back adds the clay breeze, and leaching aluminium wherein generates aluminum trichloride solution, the settlement separate unreacting substance of removing;

(3) at normal temperatures and pressures, salt is added in the aluminum trichloride solution must mix saltwater brine;

(4) at normal temperatures and pressures, mix the reaction of saltwater brine and hydrofluoric acid and generate sodium aluminum fluoride (Na ₃AlF ₆), get cryolite slurry;

(5) then cryolite slurry is filtered the dry sand like synthetic cryolite finished product that gets.

2, clay bittern method according to claim 1 is characterized in that the clay breeze is soft clay or flint clay or bauxitic clay, contains Al ₂O ₃〉=25%, fineness is 80 orders.

3, clay bittern method according to claim 1 is characterized in that content of hydrochloric acid in the leaching liquid (weight percent) is 8～20%, and leaching temperature is 40～95 ℃, and the add-on of clay breeze is according to the quantity meter of hydrochloric acid, Al ₂O ₃Measure excessive 20～40%(weight percent).

4, clay bittern method according to claim 1 is characterized in that the mixing solutions of aluminum chloride and salt, and the molecular ratio of its aluminium and sodium is 1: 3.

5, clay bittern method according to claim 1 is characterized in that in the sodium aluminum fluoride building-up reactions that the content of feed hydrogen fluoric acid (weight percent) is 10～25%, its H ₂SiF ₆Content be 0.2～0.3%, its proportioning is Al: Na: F=1: 3: the 6(molecular ratio), can adopt and be interrupted or synthetic continuously.

6, clay bittern method according to claim 1 is characterized in that the filtration of cryolite slurry can be adopted vacuum filtration or press filtration or centrifuging.

7, clay bittern method according to claim 1 is characterized in that drying temperature is 150 ℃～300 ℃, can adopt air stream drying or rotary kiln direct drying or revolution indirect heating drying.

8, clay bittern method according to claim 1 is characterized in that the filtering filtrate of cryolite slurry contains hydrochloric acid, returns as leaching liquid to recycle, and need not add hydrochloric acid.