Anti-Corrosion Paint and Varnish Coatings Employing Wastes from Coke and Coal Chemicals Production

Abstract

The various shops of the West Siberian Metallurgical Combine operate 392 gas-cleaning units, and the combine annually spends 1.5 million rubles a year on major repairs to this equipment. The need to increase the service life of the air ducts is obvious. At the same time, the production of phthalic anhydride (PA) from commercial grades of naphthalene made at coke and coal chemicals plants also yields large quantities of waste products formed in oxidation reactions – still residues from the distillation of PA. These residues are currently used in coking charges. It is important that a way be found to recycle wastes from the production of phthalic anhydride, which is the main raw material used to make corrosion-resistant paints and lacquers. The goal of the research described below was to use PA production wastes to help develop promising new environmentally clean materials to protect metal from corrosion. Such materials are presently in very short supply. The problem was solved by taking two approaches: creating a new generation of paints – powdered polymer-based compositions without solvents, for painting pipes and rolled products; synthesizing chemically stable alkyls – epoxide primers for protecting existing equipment from abrasion and corrosion. The powdered polymer-based paints – which have an efficiency of 97–98% – harden in 10–30 min. One kilogram of one of these paints takes the place of 5 kg of oil-based paint, and the powder coatings last 2–3 times longer than solvent-based paints. The combine has developed and mastered the production of two types of powdered polymer-based paint: quick-drying epoxide paint PEFAN-501; decorative epoxide-polyester paint NOVOLAN-1605. A section to make these paints has been set up and equipped with three units that apply the paints in an electrostatic field. The combine has also developed a technology for using PA still residues to obtain an alkyl-epoxide primer for protecting gas pipes from corrosion. Experimental batches of the primer have been successfully tested on a section of gas pipe connected to the car dumper in the crushing-sorting plant operated by the sinter-lime department. It has been recommended that the technology be introduced by organizing a section directly within the PA shop to produce produce alkyl resins, lacquers, and primers. Such a section could supply the combine with all of the anti-corrosion materials it needs while making the shop itself more profitable.