Aluminum Company of America

Alcoa Inc.

Alan Pearson

John E Marhanka

Edward S Martin

Hubert L Fleming

Michael A Easley

Jon F Edd

Ching-Chung Huang

Chin-Liang Chou

Hisashi O Kono

Steven W Sucech

Paul J The

Mark L Weaver

Thomas G Swansiger

Leroy D Hart

Masaki Madono

Dinesh Moorjani

James R Wall, Deceased

Leonard W Haleen

Low temperature mineralization of alumina

A composition and process for making an insulating refractory material. The composition includes calcined alumina powder, flash activated alumina powder, an organic polymeric binder and a liquid vehicle which is preferably water. Starch or modified starch may also be added. A preferred insulating refractory material made with the composition has a density of about 2.4-2.6 g/cm.sup.3 with reduced thermal conductivity, compared with tabular alumina. Of importance, the formulation has good abrasion resistance and crush strength during intermediate processing (commercial sintering) to attain full strength and refractoriness, good abrasion resistance and crush strength.

Composition and process for making an insulating refractory material

There is disclosed an improved method for making synthetic meixnerite having reduced carbonate contamination levels and a x-ray diffraction pattern resembling that shown in FIG. 1, the meixnerite is made by combining magnesium oxide and transition alumina, preferably an activated alumina powder having a BET surface area of about 100 m.sup.2 /g or greater, in a substantially carbonate-free environment.

Method for making a synthetic meixnerite product

A method of manufacture including bringing seed and aluminum hydroxide together in an aqueous medium and hydrothermally digesting for producing boehmite at the expense of the aluminum hydroxide is described. Also disclosed is a process for forming a ceramic body from colloidal boehmite and alpha alumina. Alpha alumina is added to ultimately produce a seeded gel containing microcrystalline boehmite, the seeded gel capable of being sintered at a low temperature to produce a ceramic product. The colloidal boehmite may be purified by ion exchange to remove alkali metal ions.

Production of aluminum compound

A method for the production of aluminum hydroxide, including reacting water in the liquid phase and aluminum at a pH above about 12.4. In this pH range, aluminum hydroxide is produced at acceptable rates both for aluminum surface areas above 75,000 mm.sup.2 /g and for aluminum surface area of less than about 50,000 mm.sup.2 per gram, and even down to 20 mm.sup.2 per gram. According to an alternative view of the invention, it is characterized by the production of aluminum hydroxide by reacting aluminum with liquid water containing choline. Aluminum hydroxide particles having unique morphologies are obtained.

Aluminum hydroxide production

A method of manufacture including bringing seed and aluminum hydroxide together in an aqueous medium and hydrothermally digesting for producing boehmite at the expense of the aluminum hydroxide.

A method of producing small diameter titanium carbide whiskers is disclosed. The method comprises supplying a source of materials comprised of titanium halide, hydrocarbon gas and nickel and reacting this material in the presence of a source of carbon monoxide to produce small diameter titanium carbide whiskers.

Process for production of small diameter titanium carbide whiskers

Small sized alpha alumina particles and platelets

Disclosed is a method capable of forming complex green body shapes containing alumina for forming into ceramic products. The method comprises providing a slurry containing alumina powder and an aqueous solution in an amount to provide a high level of solids in the slurry and adding to the slurry rehydratable alumina powder to provide a mix, the rehydratable alumina being present in an amount sufficient to cause the mix to harden. The mix is then permitted to harden to a solid body suitable for firing into a ceramic product.

Process for producing ceramic shapes

A process for making alpha alumina particles wherein a Bayer process caustic aluminate solution is treated with both alumina hydrate seed material and alpha alumina promoter particles to precipitate alumina hydrate particles. The precipitated particles are separated from the solution and then dried and calcined to produced alpha alumina particles. Addition of promoter particles in the precipitation step lowers the calcination temperture necessary to produce alpha alumina and results in smaller sized crystallites in the product.

Economical process for alpha alumina production

Disclosed in a process for forming a ceramic body from colloidal boehmite and alpha alumina. Alpha alumina is added to the colloidal boehmite to produce a seeded gal, the seeded gel capable of being sintered at a low temperature to produce a ceramic product having at least a 90% theoretical density.

Alumina ceramic product from colloidal alumina

The process of the present invention for preparing granules of alumina includes pretreating an alumina powder by admixing with cold water in a mixer at a temperature below room temperature, e.g., such as below about 20.degree. C., to form a pretreated alumina having a pore volume saturated with water and further having a surface area of gel structure, and agglomerating the pretreated alumina in a fluidized bed to form granules. The process is particularly suited to producing activated alumina in macroporous granules. The process in one aspect further includes a cold hopper for cooling alumina powder prior to the pretreating step.

Producing alumina granules in a fluidized bed

The process of the present invention for preparing granules of alumina includes pretreating an alumina powder by admixing with cold water in a mixer at a temperature below room temperature, e.g., such as below about 20.degree. C., to form a pretreated alumina having a pore volume saturated with water and further having a surface area of gel structure, and agglomerating the pretreated alumina in a fluidized bed to form granules sized in the range of about 1-3 mm. The process is particularly suited to producing activated alumina in macroporous granules. The process in one aspect further includes a cold hopper for cooling alumina powder prior to the pretreating step.

Fluidized bed granulation of rehydratable alumina

(1) Rehydration bondable alumina of median particle size less than 5 microns, LOI (250.degree. to 1100.degree. C.) about 4 to 12% by weight, and having the ability to yield rehydration bonded objects of lower density and higher strength as compared with objects made of seven micron rehydration bondable alumina, or density less than 0.9 cm.sup.3 /g at strength about equal to or greater than 7 MPa; (2) rehydration bondable alumina having the ability to yield rehydration bonded objects having at least 0.6 cc of pore volume per gram for pores smaller than 300 Angstroms. Also encompassed are materials containing such alumina and originating from e.g. bauxite.

Rehydration bondable alumina

A process for removing organic contaminants from a mineral ore such as bauxite. The ore is washed with an aqueous solution containing caustic soda, sodium carbonate or mixtures thereof in an amount up to about 80 g/l total alkali content (expressed as sodium carbonate equivalent). The ore is preferably washed at a temperature of about 95.degree. C. for about 5 hours with a solution containing about 20 g/l total alkali content. In a preferred embodiment, the ore is separated from a rinse solution containing degradation products of organic contaminants, and the washed ore is then dissolved in a caustic solution to produce Bayer process liquor. This process provides a means to reduce the organic carbon concentration in Bayer process liquor, with resultant increase in productivity of the Bayer process.

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Murrysville, PA, United States of America

Alan Pearson