Acid recovery
Chematur Ecoplanning has great experience in the regeneration of acids. The technology used is based on the process of acid regeneration resulting from the production of titanium dioxide, explosives, and derivatives of nitrates in the metallurgical industry. The many successfull acid recovery plants already in operation have made Chematur Ecoplanning a well known and trusted name in this field.
In the Titanium Dioxide (TiO ) industry alone, more than 4.0 million tonnes of spent acid 2
are processed annually in Chematur Ecoplanning plants, which amounts to 1.9 million tonnes of water evaporation annually.
Preconcentration Ageing Filtration Final concentration
Acid Recovery Technology Preconcentration with contaminant separation Diluted acid of 5 to 20 % must be concentrated to a level of 70 %. At this concentration the solubility of most metals in sulphuric acid is lowered to such a degree that contaminants can be precipitated and separated. After pre-concentration it may be necessary to remove some substances by chemical precipitation, which can result in practically pure acid. It is, of course, desirable that the acid after preconcentration and chemical treatment can be accepted for reuse in the process. Concentration up to 70 % is commonly performed in a three-stage evaporator, under vacuum. The forced circulation technique is most commonly applied in the evaporator, but falling film can also be considered if the acid is relatively free of difficult metal salts. The construction materials are highly dependent on the contaminants in the waste acid. Typical materials used by Chematur Ecoplanning are special plastics, graphite and silicon iron.
High Concentration Sometimes after preconcentration it is necessary to have a concentration of around 90 % H2SO4 and a separation of solids formed. The acid produced meets still higher requirements compared to the acid from preconcentration, but operation and investment costs are also relatively higher. The typical system for this application is a single or double stage forced circulation evaporator, which is operated under high vacuum. Requirements for materials in respect to corrosion are still greater, which means that materials such as tantalum and enamelled steel come into the picture. These materials are expensive, and need special care in manufacturing and installation. However, under severe conditions the low corrosion rates of the expensive materials will compensate the higher investment in the form of lower maintenance costs.
Chematur Ecoplanning Chematur Engineering Group Chematur Ecoplanning Oy P.O.B. 78, FIN-28101 PORI, FINLAND, Tel. +358 2 6240 200, Fax +358 2 6240 290 e-mail: info@ecoplanning.fi
AM-mainos/Printed in Finland byHermes 2003
Application for Removing Non-Volatile Inorganic Contaminants from Spent Acid