12. A manufacturing process of alumina, comprising the following steps: manufacturing a pseudo-boehmite of claim 1, and calcining the pseudo-boehmite to obtain the alumina. ... Manufacturing of Pseudo-Boehmite. Aluminium hydroxide and sodium hydroxide were mixed and boiled to formulate a solution with a concentration of 345 gAl 2 O 3 /L, ...
Process for Preparing Pseudo-Boehmite from Aluminium Trihydrate Saravanan Poomalai1 and Nageswar Kapuri2 1. General Manager (Specialty Application R&D) 2. Asst. Vice President Hindalco Innovation Centre – Alumina Hindalco Industries Limited, Belagavi, India Corresponding author: [email protected] Abstract
In the beginning of the process, the aluminum powder is fully oxidized during few seconds in water steam at temperature about 570 K. ...
The pre-aging process was performed by adding boehmite to a nano grade α-alumina (Nα-A) slurry and adjusting the pH value of the mixed slurry to less than 4. After the pre-aging process, boehmite was coated onto the surface of Nα-A particles to change its zero charged point (PZC) from pH = 6–7 to 9–10, similar to that of the boehmite slurry.
1. Preparation method of boehmite. Boehmite is a thermodynamic metastable phase, which is easy to dehydrate at high temperature to form aluminum oxide. At present, there are many synthetic methods of boehmite, mainly including sol-gel method, aluminum alkoxide salt solution method, aluminum direct hydrolysis method and hydrothermal method.
The topotactic transformation of boehmite (AlOOH) taking place under calcination and leading to γ-alumina (γ-Al2O3) has been investigated theoretically and a step-by-step mechanism for the structural transformation is proposed. This mechanism reveals two major steps. First, the structural collapse of boehmite occurs, after hydrogen transfers and water extraction. Then, …
In this process the alumina slurry is aged at a pH of 5 to 9 at a temperature above 70 o C for enough time to convert the greater part to a colloidal sol. A further process of making a boehmite product is known from EP-A-0 304 721. Said process uses a seeding mechanism to produce a boehmite from precursor material.
J.L. Sudworth, R.C. Galloway, in Encyclopedia of Electrochemical Power Sources, 2009 Production. The production of β alumina powder is based on the boehmite route. The boehmite (aluminum oxide monohydrate Al 2 O 3 ·H 2 O) is calcined at around 800 °C in an indirect, gas-fired, rotary calciner in which a metal tube is heated from the outside. The calcined material, …
What is claimed is: 1. A method for producing high porosity boehmite alumina comprising: mixing an aqueous boehmite alumina slurry with an effective amount of a modifier comprising a hydroxide or oxide of an element of Group IIIA-VIII of the Periodic Table of Elements and having a pKsp of greater than 11 to produce a precursor mixture; and hydrothermally aging said …
A boehmite or boehmitz precursor can be improved in its dispersibility by subjecting it to a hydrothermal treatment at a pH of less than 3.5 and at elevated temperature and pressure. ... 238000004519 manufacturing process Methods 0.000 title 1; ... * Process for preparing dispersible boehmite alumina () * () * () * ...
What is claimed is: 1. A process for the preparation of a fine flaky boehmite particle having an orthorhombic crystal form, a crystal face grown in the form of a flat plate, major and minor axes of the order of submicron and a ratio of the major axis to the minor axis between 1 and 5, said process comprising the step of subjecting aluminum hydroxide or hydrated alumina having a …
The calcination step absorbs 3 GJ/t alumina or 25% of the total Bayer process. The objective of the current project is to develop a highly innovative modification of the Bayer process, whereby aluminum monohydrate (boehmite, Al2O3.H2O) rather than the trihydrate will be the product of the precipitation stage.
A boehmite or boehmite precursor can be improved in its dispersibility by subjecting it to a hydrothermal treatment at a pH of less than 3.5 and at elevated temperature and pressure. ... boehmite dispersion alumina dispersibility starting material Prior art date ... 238000004519 manufacturing process Methods 0.000 title claims description 11;
A process for making high porosity boehmite alumina comprising forming an aqueous dispersion of a boehmite alumina which has been obtained by hydrothermally treating an aqueous mixture of a precursor boehmite alumina at a pH of from about 5 to about 9 for a period of time sufficient to convert the greater portion of the precursor boehmite alumina to a …
The first stage of this process was synthesis of a stable boehmite sol (γ-ALOOH) by dissolving alumina-tri-secondary butoxide in deionized water at 75°C. The obtained solution was peptized with 1.0 M HNO 3 and refluxed at 90–100°C for 10 hours to obtain a stable boehmite sol. Granular boehmite beads with a median diameter of about 2 mm ...
1. A process for preparing divalent metal-Al-containing anionic clays comprising peptizing boehmite in a aqueous slurry with an acid and adding a divalent metal source to said slurry in an amount that is at least stoichiometric with respect to the aluminum in said boehmite, adding a base to said slurry in an amount comprising from about 0.10 to about 0.30 moles of …
ERZMETALL 56 (2003) Nr. 2 77 Dimitrios Panias et al.: Boehmite Process – A New Approach in Alumina Production creases from 230 g/L (normal precipitation) to 1200 g/L
The novelty of this process is related to the production of pure crystalline Boehmite, alumina monohydrate, at the precipitation stage as an …
For determining the adsorption energy ( ) of the starting n 3n (n=1 to 3) oxides oligomers on alumina at 0 K, the following equation was used: This study focused on the (100) surface of -alumina ...
