Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F7/00—Compounds of aluminium
  • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
  • C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F7/00—Compounds of aluminium
  • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
  • C01F7/46—Purification of aluminium oxide, aluminium hydroxide or aluminates
  • C01F7/47—Purification of aluminium oxide, aluminium hydroxide or aluminates of aluminates, e.g. removal of compounds of Si, Fe, Ga or of organic compounds from Bayer process liquors
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/36—Regeneration of waste pickling liquors

Definitions

• the present invention relates to a method for cleaning and concentrating alkali aluminate solutions which are obtained in the aluminum processing industry.
• the invention further relates to the processing of aluminum hydroxide-containing sludges and filter cakes to give liquid or solid alkali aluminates.
• the following sections provide examples of some materials that can be used for the present invention.
• waste liquids which also contain dissolved sodium aluminate and thus in the sense of the present invention
• SPARE BLADE (RULE 26) - __ - can be used.
• Aluminum-containing waste solutions also arise during the reprocessing of aluminum-containing catalysts and e.g. in platforming catalysts and also in the production of Raney nickel, which is a particularly pyrophoric form of nickel and is used as a catalyst in many chemical processes.
• Raney nickel is made by first nickel with metals, e.g. is alloyed with aluminum, silicon, magnesium or zinc and then this alloy is treated with sodium hydroxide solution or potassium hydroxide solution after mechanical grinding. This removes catalytically inactive metal, leaving a black metal sponge as "active nickel".
• the waste solutions resulting from this process, provided aluminum is an alloy component, can be used as a starting material in the sense of the present process.
• extrusion plays a major role in the production of profiles from blocks and bars.
• aluminum residues remain in the pressing tool, which must be removed.
• the best way to dissolve them is with sodium hydroxide solution.
• the alkaline solutions obtained here represent nothing other than a more or less contaminated sodium aluminate solution and can therefore also be used for the purposes of this invention.
• Alkali aluminates generally arise from the dissolution of solid ones
• aqueous alkali solutions for example sodium hydroxide or potassium hydroxide, can be used for the dissolution of the solid aluminum-containing residual substances.
• all aluminum hydroxide-containing sludges and filter cakes can be used which result from the neutralization of alkaline or acidic aluminum-containing waste solutions, e.g. if you combine alkaline anodizing eyes with sulfuric acid electrolyte from the aluminum anodizing process (USP 4,265,863 / USP 3,909,405).
• Suitable aluminum hydroxides also arise during the regeneration of the pickling bath according to DE OS 40 08 379, in which aluminum hydroxide is precipitated in situ.
• the low-temperature forms of aluminum oxide belonging to the gamma group are also suitable for the process according to the invention. They arise from the aluminum hydroxides by heating to 400 to 750 ° C and, due to their large pore volumes and their large specific surfaces, are used as catalysts in the dehydrogenation of alcohols, as catalyst supports, drying agents and as chromatography column fillings for the separation of natural products. Contaminated materials from the uses mentioned above dissolve in hot concentrated alkali lyes and are the raw material for this method according to the invention suitable. Also only partially resolvable
• Material can be used in the process according to the invention.
• Powders can be produced. According to this process, it should also be possible to use several alkali aluminates with different consistencies and different molar ratios of alkali oxide to Al O and Al O
• alkali metal hydroxide solution is used to dissolve the aluminum contained in the sediment or added sludge, and thus to set the alkali oxide / Al O molar ratio in the range from 1 to 5, preferably 1 to 2.
• the solutions in la) and b.) Show before the first Oxidation has an alkali oxide / Al O molar ratio of less than 5, preferably 0.9 to 3, in particular 1.2 to 2, and an Al O content of 3 to 20% by weight.
• the contaminated waste solutions are oxidized with an oxidizing agent, preferably hydrogen peroxide, in order to decolorize the solutions.
• an oxidizing agent preferably hydrogen peroxide
• the oxidation is carried out at the appropriate temperature, preferably at room temperature. All common agents are suitable as oxidizing agents, e.g. H O, sodium perborate and others Depending on the degree of contamination, 0.05 to 0.5% by weight of oxidizing agent, based on the amounts used, are added.
• the solutions can also be decolorized by adsorbing the coloring impurities on activated carbon.
• the solution is heated to 50 to 100 ° C., preferably 70 to 80 ° C., in order to lower the viscosity.
• the mechanical separation removes any remaining cloudy turbidity.
• All separation processes can be used individually or in combination, e.g. Sedimentation with precoat filtration, with centrifugation and "cross-flow" membrane filtration. It has proven to be particularly advantageous to use auxiliary substances, e.g. Trimercapto-s-triazine (TMT) or di-2-ethylhexyl dithiophosphate for precipitating and / or complexing heavy metals, and / or adding organic flocculants or polyelectrolytes in conjunction with activated carbon to improve the mechanical separation.
• TTT Trimercapto-s-triazine
• di-2-ethylhexyl dithiophosphate for precipitating and / or complexing heavy metals
• organic flocculants or polyelectrolytes in conjunction with activated carbon to improve the mechanical
• the intermediate product ZP 1 thus formed is now subjected to the second mechanical cleaning, whereupon residues from the first cleaning, turbidity precipitated by concentration, and any undissolved parts of the substances added under 4. are removed.
• This step can be carried out in the same way as for the 1st mechanical cleaning, using auxiliaries and using the various separation processes already mentioned under point 3.
• the intermediate product ZP 1 can optionally be decolorized before step 5 with the aid of oxidizing agents if such constituents should still be present or have been introduced in step 4. You can also remove the coloring components with activated carbon.
• the first end product EP 1 is already available in the form of a bright and clear solution and can be used for all known purposes. It has an alkali oxide / Al O molar ratio of at least 1 to 2 and an Al O content of 10 to 25% by weight.
• Alkaline oxide / Al O ratio can be used with different products
• the end product EP 1 can be concentrated to an AlO content of 25 to 33% by weight by water evaporation and then this solution can be dried in a spray dryer or in another suitable unit.
• the advantage of this method is that the solid end product EP 2 is produced in a free-flowing consistency with a low bulk density. This can have advantages in some applications, e.g. in the building materials industry.
• Solution EP 1 is evaporated to a solid by water evaporation and then calcined in a rotary kiln.
• Example 1 Production of sodium aluminate from anodized eyes and moist hydrate
• the intermediate product 1 was then increased with 1, 24 1 aluminum hydroxide (moist hydrate, corresponding to 0.719 t Al 2 0 3 ) to the final content of 18.4% Al 2 0 3 .
• the solution was treated with a polymeric flocculant (8 ppm Alciar W5, Allied Colloids GmbH, Hamburg), sedimented overnight (12 h) and the supernatant was subjected to clarification by means of a filter with a washed filter aid layer made of Celiulose.
• the solution which is still yellow after clear filtration, is oxidized again with 0.15% hydrogen peroxide (added as a 30% solution) and is then water-clear with a slight yellow tinge.
• the product is a clear, slightly yellowish solution that is already viscous at room temperature.
• the analysis is shown in Table 1 below.
• the strongly colored, solids-containing, still hot product was mixed with a polymeric flocculant (8 ppm Mikrosorban 502, Giulini Chemie GmbH, Ludwigshafen), sedimented overnight (1 2 h) and the supernatant, using a filter with a washed-on filter auxiliary layer made of Celiulose, subjected to a clear filtration.
• the solution which was cooled to about 40 ° C. after the filtration, was treated with 0.15% hydrogen peroxide (added as a 30% solution) for decolorization.
• the product is a clear, almost colorless, viscous solution.
• the aluminum-containing, alkaline, black-gray, solid-containing residue solution solution, characterized in more detail in Table 3, from the Raney nickel production was placed in a 25 m 3 container according to which. Oxidation with 0.15% hydrogen peroxide (addition as a 30% solution), heated to about 80 ° C. and then freed from the solids in accordance with Example 1. The supernatant was thickened to about 82% of its mass, to intermediate 1, in a single-stage expansion evaporator. The concentrate from the evaporator was pumped into an open, heatable reactor, aluminum hydroxide was added there and the mixture was evaporated to about 77.4% of its mass (intermediate product 2).
• the intermediate product 2 was placed in a rotary kiln, calcined and then ground.
• the solid sodium aluminate produced is a hygroscopic, eggshell-colored powder with a bulk density of approx. 0.8 g / cm 3 , which has a very good solubility in water.
• the contents of the individual levels are listed in Table 3.
• Table 3 Analyzes of starting material, intermediate products and product in the production of solid sodium aluminate from residual aluminum hydroxide solution in three stages
• Nickel ppm 43 1 1 12 17 Example 4: Preparation of solid sodium aluminate from aluminum-containing, alkaline residues solutions in two stages.
• Precoat layer Celiulose, 1 cm thick, the precoat layer was applied to the filter from an approx. 2.5% suspension. The continuous acceptance of the fitter cake was carried out with a hydraulic scraper acceptance.
• Drum speed 0.3 to 1 rpm.
• Spray dryer data electrically heated
• the solid sodium aluminate produced by spray drying is a hygroscopic, eggshell-colored, fine powder whose bulk density is about 0.1 g / cm 3 and which dissolves very well in water.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• General Chemical & Material Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Health & Medical Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
• Processing Of Solid Wastes (AREA)
• Removal Of Specific Substances (AREA)

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• 1993
  • 1993-04-08 DE DE4311716A patent/DE4311716C1/de not_active Expired - Fee Related
• 1994
  • 1994-04-07 SK SK1259-95A patent/SK283913B6/sk unknown
  • 1994-04-07 WO PCT/EP1994/001081 patent/WO1994024050A2/de not_active Ceased
  • 1994-04-07 PL PL94310826A patent/PL310826A1/xx unknown
  • 1994-04-07 EP EP94916913A patent/EP0693040A1/de not_active Withdrawn
  • 1994-04-07 CZ CZ19952613A patent/CZ290971B6/cs not_active IP Right Cessation

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