"Scientific-research and Project Institute “TOMS” LLC, Irkutsk, Russia

Yu. G. Seredkin, Researcher

National University of Science and Technology “MISiS”, Moscow, Russia

A. P. Lysenko, Assistant Professor of a Chair of Non-ferrous Metals and Gold

The aim of work is research of influence of parameters of electrolysis on aluminium hydroxide particles size. A theory is studied and technology of the fine aluminium hydroxide generation by an electrolytic method is worked out. Anodic and cathode polarization curves of aluminium are obtained by galvanostatic method. Dependences of current efficiency and specific product outcome from the current density are studied on a cathode. Kinetics of enlargement of aluminium hydroxide particles is investigational and duration of height of particles is certain to beginning of besieging. Influence of current density is studied on the particles size and the maximal size is certain. As a result of study of electrode processes of aluminium hydroxide generation by electrolysis in salt electrolyte is established, that in addition to the electrochemical formation of aluminum hydroxide on the anode and the emission of hydrogen at the cathode, there is a chemical dissolution of the cathode with the formation of sodium aluminate. Current efficiency does not depend on the anodic current density and is 117% at equilibrium correlation of ions of aluminium in solution 78.2% Al³⁺ ions and 21.8% Al⁺ ions. Total current efficiency makes at current density 0.030 A/cm² approximately 150%, and at the increase of temperature to 70 ^oC arrives at 170%. It is set at the study of kinetics of enlargement of aluminium hydroxide particles, that phase transformations of aluminium hydroxide originate from the colloid state to formation of Al(OH)₃ in hydrargillite form and result in a division solid and liquid phases due to the stage-by-stage increase of sediment density. Duration of phase transformations, necessary for the height of aluminium hydroxide particles, is 30–40 min. The study of influence of current density on the aluminium hydroxide particles size allowed to define the maximal size that makes 8–9 μm and arrived at the current density 0.045 A/cm². As a result of undertaken studies dependences, that allow to get fine aluminium hydroxide with the size of particles suitable for using as an antipyren filler for polymers.

1. Gornaya entsiklopediya (Mining encyclopedia). Under the editorship of E. A. Kozlovskiy. Moscow : Sovetskaya entsiklopediya, 1984–1991.
2. GOST 11069–2001. Alyuminiy pervichnyy. Marki. Pereizdanie s popravkoy (State Standard 11069–2001. Primary aluminium. Grades. Republication with correction). Moscow : Publishing and Polygraphic Complex, Publishing House of Standards, 2008.

3. Evropeyskiy standart EN 573-3:2009. Alyuminiy i alyuminievye splavy. Khimicheskiy sostav i forma polufabrikatov. Chast 3. Khimicheskiy sostav i forma izdeliy (European standard EN 573-3:2009. Aluminium and aluminium alloys. Chemical composition and shape of half-finished products. Part 3. Chemical composition and shape of products). Brussels : European Standards Committee, 2009.
4. GOST 4233–77. Reaktivy. Natriy khloristyy. Tekhnicheskie usloviya. Pereizdanie s izmeneniyami No.1, No.2 (State Standard 4233-77. Reagents. Sodium chloride. Technical requirements. Republication with corrections No.1, No.2). Moscow : Publishing and Polygraphic Complex, Publishing House of Standards, 2008.