CN1168660C - Process for preparing industrial aluminium fluoride from acidic aluminium slag - Google Patents

Abstract

The present invention discloses a method for preparing industrial aluminium fluoride from acidic aluminium slag. The acidic aluminium slag is a waste precipitated out from surface corrosion technological treatment in the production process of an aluminium section, and the waste comprises components of ammonium fluoroaluminate, a small amount of other aminium salt and trace quantity of mixture composed of ferric silicon impurities. An obtained dry raw material is added with a mixed solution of 1 to 30% of HF and 1 to 30% of HCl after being pulverized uniformly, the dry raw material and the mixed solution is stirred for 60 to 90 minutes under the preserved normal temperature of-80 DEG C, and a compound of the ferric silicon impurities reacts with HF acid and HCl acid to generate a soluble substance which is separated from the insoluble acidic aluminium slag; then the raw material can be separated from a mother solution by filtration, the raw material and the mother solution are washed by clear water and filtered dryly, a dry filtered article is put in a drying device of 120 DEG C to be dried for 1 hour and is taken out to be pulverized into powder which is put in a high-temperature furnace to be heated at the temperature of 500 to 800 DEG C and decomposed for 40 to 60 minutes, and the powder is taken out to be cooled to manufacture the aluminium fluoride. The raw material is sourced from the waste, resources are recycled and saved, the present invention is beneficial for environmental protection, and a by-product of ammonium fluoride can be recycled; therefore, the method has the advantages of simple technology, low cost, quality satisfaction and obvious economic benefits.

Description

The method of preparing industrial aluminium fluoride from acidic aluminium slag

(1) technical field:

The present invention relates to chemical industry, particularly a kind of method with preparing industrial aluminium fluoride from acidic aluminium slag.

(2) background technology:

The industry aluminum fluoride is generally white crystal or powder, makes the electrolytic bath component in electrolytic industry, in order to reduce fusing point and to improve electrolytical specific conductivity.At present, the production of aluminum fluoride is divided into two kinds of dry method and wet methods, but no matter be which kind of method, aluminium element derives from aluminium hydroxide or aluminum oxide, and fluorine element derives from the hydrogen fluoride of fluorite and sulfuric acid reaction generation.These two kinds of method complex process, number of devices are more, especially aluminum fluoride by dry process production, and investment is big, cost is high.

(3) summary of the invention:

The purpose of this invention is to provide a kind of method with preparing industrial aluminium fluoride from acidic aluminium slag, it has that technology is simple, use equipment is few, investment is little, instant effect, can utilize waste---the acidic aluminium slag of aluminium section bar industry, produces very low, the qualified aluminium fluoride product of cost.

The method of preparing industrial aluminium fluoride from acidic aluminium slag: aluminium element content is 10～20% in the acidic aluminium slag, fluorine element content 50～60%, composition a great deal of ALF ₃44.87%, NH ₄F50.19%, (NH ₄) ₂SO ₄And small amount of impurities 4.94%, it is characterized in that:

A, pulverizing are pulverized the dried raw material of acidic aluminium slag evenly with pulverizer earlier;

B, silica removal iron contamination, dried raw material after pulverizing is contained in the container, the mixed solution that adds concentration 1～30%HF-1～30%HCL carries out chemical reaction under stirrer stirs, make the compound of ferrosilicon impurity generate soluble substance and separate with insoluble acidic aluminium slag with HF acid, HCL acid-respons.Reaction conditions be temperature the temperature remains within the normal range～80 ℃, churning time 60～90 minutes;

C, filtration, washing, oven dry, grinding make reacted surplus stock and liquid separation with the strainer filtration, and do with clear water washing filter, place 120 ℃ drying plant to dry by the fire 1 hour the filter dry, use the shredder grinding powder again;

D, thermolysis are put into High Temperature Furnaces Heating Apparatus with c step gained powder, decompose 40～60 minutes down for 500～800 ℃ in heating, after decomposition is finished, take out cooling, promptly make the finished product aluminum fluoride.

Advantage of the present invention is: 1, the recyclable aluminium section bar industry depleted acidic aluminium slag that utilizes is produced industrial aluminum fluoride; in producing process, can also reclaim the byproduct Neutral ammonium fluoride; utilize Neutral ammonium fluoride can produce hydrofluoric acid and another kind of product ammonium salt such as ammonium chloride or ammonium sulfate again; can make chemical fertilizer uses; economize on resources, help environment protection.2, technology is simple, use equipment is few, little, the instant effect of investment, compares with wet production, and production cost is 1/3～1/4 of a wet method only, and remarkable economic efficiency is arranged.3, quality product, performance reach the requirement of national GB4292-1999 primary standard.

(4) description of drawings:

Fig. 1 is a process flow sheet of producing aluminum fluoride with acidic aluminium slag.

(5) embodiment:

Below in conjunction with accompanying drawing the present invention is done to describe in further detail:

One, the formation of acidic aluminium slag:

The definition of acidic aluminium slag: be meant that aluminium section bar is called acidic aluminium slag with the solid mixture (mainly containing fluorine element, aluminium element, ammonium root) that chemical corrosion liquid carries out surperficial acid corrosion back generation.

The aluminium section bar industry is used a large amount of aluminium ingots, mixes a small amount of silica flour processing and is converted into aluminium section bar.The aluminium shape surface that squeezes out is one deck aluminum oxide, has metalluster, and is not attractive in appearance, and its surface need be carried out surface corrosion with acid or alkali electroless mixed solution and be handled.The acid etch treatment effect that developed recently gets up is fine, and present aluminium section bar almost all need carry out the surface chemistry corrosion treatment, and great majority are the acid corrosion.Acid corrosion is that aluminium section bar is put into and wherein carried out the chemical surface corrosion with chemical agents such as mineral acid (as sulfuric acid, hydrochloric acid), ammonium acid fluoride, adjustment agent wiring solution-forming by a certain percentage, through certain hour, reach certain depth of corrosion, handles promptly to accuse and finishes.The ammonium salt of reaction process generation aluminum fluoride, corresponding mineral acid and silicofluoric acid etc., these materials mix, form more complicated material under given conditions, along with the chemical corrosion liquid concentration that recycles increases, part solid mixt is separated out from corrosive fluid, after centrifuging or press filtration, solid part promptly constitutes acidic aluminium slag, and filtrate reenters circulation after replenishing.

Two, the composition of acidic aluminium slag:

1, outward appearance: acidic aluminium slag produces because of separating out to filter from solution, is wet shape solids, and white is grey slightly, is acid, and it is 1～3 that the wetted portions test paper detects pH value, band viscosity, and seasoning or oven dry back are the light gray-white solid, can grind to form the powdery solid.

2, chemical ingredients: can analyze from the acidic aluminium slag production process, acidic aluminium slag is a kind of mixture, has both contained solid matter, contains liquid substance again, has both comprised reaction product, comprises unreacted reactant again.

With the siccative that forms after the acidic aluminium slag raw material stoving, through qualitative and quantitative analysis, its composition (representing with a great deal of) is as following table 1:

Table 1

Composition	ALF 3	NH 4F	(NH 4) 2SO 4And small amount of impurities	Add up to
					Content %	44.87	50.19	4.94	100

Confirm that through X-ray diffraction analysis the composition of siccative is mainly (NH ₄) ₃ALF ₆(NH ₄) ₂ALF ₅Therefore, the mixture that mainly constitutes of siccative by ammonium aluminum fluoride and a small amount of other ammonium salts and Trace Silicon, iron contamination.

Three, the acidic aluminium slag raw material is produced the operational path of aluminum fluoride:

By analytical results as can be known, aluminium element is a metallic element in the raw material, and it links to each other with covalent linkage with the F atoms of elements, the ionic group that constitutes closes with ionic linkage and ammonium root knot again, and F element and aluminium element are active element, so the covalent linkage that constitutes is very firm, bond energy is very big, and interrupting these keys needs very macro-energy.Simultaneously, contain silicon, iron contamination in the raw material, and the ammonium salt of corresponding mineral acid should be removed.Therefore, producing the task that route will finish is: one, the removal of impurity; Two, the atom with aluminium element in the raw material and fluorine element is restructured as aluminum fluoride through chemical reaction.

That takes produces route:

Acidic aluminium slag raw material → pulverizing → removal of impurity → filtration washing oven dry grinding → thermolysis → aluminium fluoride product.(referring to Fig. 1)

Step:

1, the raw material of obtaining (siccative) is pulverized evenly with pulverizer earlier,, shortened the reaction times with the augmenting response contact surface.

2, the dried raw material after pulverizing is contained in the container, the mixed solution that adds concentration 1～30%HF-1～30%HCL, under stirring, stirrer carries out chemical reaction, making the compound of ferrosilicon impurity generate soluble substance and separate reaction conditions with insoluble acidic aluminium slag with HF acid, HCL acid-respons: the temperature remains within the normal range for temperature～and 80 ℃; Churning time 60～90 minutes.

3, filter, wash, dry, grind.Make reacted surplus stock and liquid separation with the strainer filtration, and do, place 120 ℃ drying plant to dry by the fire 1 hour the filter dry, use the shredder grind into powder again with clear water washing filter.

4, thermolysis.

The compound that fluorine, aluminium form in the raw material is confirmed to mainly contain two kinds through X-ray diffraction analysis: (NH ₄) ₃ALF ₆(NH ₄) ₂ALF ₅The atom that also is fluorine in the raw material, aluminium element mainly is combined into hexafluoro-ammonium aluminate and five ammonium aluminum fluorides.Ammonium aluminum fluoride belongs to ammonium salt, and ammonium salt is heated to certain temperature following time, will decompose, and the ammonium root decomposes and produces ammonia NH ₃, in addition three hydrogen atoms will with [ALF ₆] ^3-Form hydrofluoaluminic acid, it at high temperature also will decompose and produce ALF ₃With HF.Said process is expressed as with reaction formula:

Five ammonium aluminum fluoride decomposition coursees:

Net result can obtain aluminum fluoride and Neutral ammonium fluoride.So just finish that fluorine atom and aluminium atom are restructured as aluminum fluoride in the raw material.A small amount of vitriolic ammonium salt or other ammonium salt in the acidic aluminium slag decompose in the lump in thermolysis and remove.

If no ferrosilicon impurity in the raw material, perhaps content is lower, and 2,3 steps can omit.

Therefore, the raw material powder that previous step is obtained is put into High Temperature Furnaces Heating Apparatus and was decomposed 40～60 minutes down for 500～800 ℃ in heating, decompose finish after, take out cooling, promptly obtain the finished product aluminum fluoride.

Through multiple instrument detecting and chemical analysis, result such as following tables 2 such as electron microscope, electron diffraction, X ray:

Table 2 chemical ingredients

Numbering	F	AL	SiO 2	Fe 2O 3	P	Na	K	H 2O
									RZ-1	64.22	31.58	0.26	0.02	0.004	0.011	0.006	1.12

Last table data all meet or exceed the above requirement of national GB4292-1999 first class product.

Four, the recycling of byproduct Neutral ammonium fluoride:

1, in producing the aluminum fluoride process, byproduct NH ₄F is created in the raw material thermal degradation process:

As the NH that produces ₃Mix under normal temperature or lower temperature with HF gas, then reaction generates solid-state Neutral ammonium fluoride:

Therefore, will produce HF gas and NH ₃Gas is introduced an air chamber simultaneously, with very fast generation NH ₄The F solid.

2, recycle.NH ₄F is a white solid, and heating easily is decomposed into HF and NH ₃Gas then generates ammonium salt and hydrogen fluoride gas with acid-respons.Collect the byproduct Neutral ammonium fluoride, make it and sulfuric acid reaction, produce hydrogen fluoride and ammonium sulfate:

The HF gas water that produces absorbs produces hydrofluoric acid, and another kind of product ammonium sulfate is commonly called as " ammonium sulphate ", can make chemical fertilizer and use.

3, vent gas treatment.Producing and reclaiming in the byproduct process, having small part to decompose the NH that produces ₃To discharge with HF gas and reaction,, will produce atmospheric pollution as not handling, so need handle treatment process: make absorption agent with water, absorb with the circulation of two-stage packed absorber, reach the finite concentration evaporative crystallization, can obtain the solid Neutral ammonium fluoride for the second time, mother liquor enters Sewage treatment systems.

Claims (1)

1, a kind of method of preparing industrial aluminium fluoride from acidic aluminium slag, aluminium element content 10～20% in the acidic aluminium slag, fluorine element content 50～60%, composition a great deal of are ALF ₃44.87%, NH ₄F50.19%, (NH ₄) ₂SO ₄And impurity 4.94%, it is characterized in that:

A, pulverizing are pulverized the dried raw material of acidic aluminium slag evenly with pulverizer earlier;

B, silica removal iron contamination, dried raw material after pulverizing is contained in the container, the mixed solution that adds concentration 1～30%HF-1～30%HCL, under stirring, stirrer carries out chemical reaction, make the compound of ferrosilicon impurity generate soluble substance and separate with insoluble acidic aluminium slag with HF acid, HCL acid-respons, reaction conditions be temperature the temperature remains within the normal range～80 ℃, churning time 60～90 minutes;

C, filtration, washing, oven dry, grinding make liquid separate with reacted surplus stock with the strainer filtration, and do with clear water washing filter, place 120 ℃ drying plant to dry by the fire 1 hour the filter dry, use the shredder grinding powder again;

D, thermolysis are put into High Temperature Furnaces Heating Apparatus with c step gained powder, decompose 40～60 minutes down for 500～800 ℃ in heating, after decomposition is finished, take out cooling, promptly make the finished product aluminum fluoride.