National Mineral Resources University, Saint Petersburg, Russia:

V. I. Bolobov, Professor of a Chair of Mechanical Engineering, e-mail: Boloboff@mail.ru

LLC “Scientific-Research Center “Gidrometallurgiya”, Saint Petersburg, Russia:
Ya. M. Shneerson, Chief Executive Officer, Professor
A. Yu. Lapin, Technical Director

The possibility of crevice corrosion of commercial titanium VT1-0 (ВТ1-0) and titanium wrought alloy VT14 (ВТ 14) was analyzed in high temperature leaching of pyrite gold concentrates in laboratory autoclave using gravimetric method. All materials were tested in the form of assemblies consisting of two plates with holes connected together using the fluoroplastic sealing material and fluoroplastic gaskets with the fixed gap of 0.1 mm and 1 mm. There is almost no corrosion on outer and side surfaces of all plates, but a brown, easily removed plaque is in local areas of the internal surfaces. Removal of the plaque found the blackened rough metal surface. If you take the maximum of the obtained values of the mass loss to the area under the metal gasket (where corrosion is fixed), the rate of destruction of titanium and its alloys may be obtained (14.5 and 0.72 mm/year, respectively). Large titanium susceptibility to crevice corrosion in autoclave work products (particularly in chloride-containing mediums) is noted. Crevice corrosion of titanium and its alloys in the products of high-temperature oxidative leaching of gold-bearing sulphide concentrates is connected with decreased concentration of oxidants (Fe₃⁺, O₂) in the gap compared with the concentration in the bulk solution and the slow removal of products of corrosion reactions leading to a common activation of the metal surface and to facilitate the anode process of its dissolution.

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