Cleaning of oil-contaminated solids

Abstract

The present invention relates to a method for treating of oil contaminated, metal-containing solids, in particular spent catalysts. The solids are cleaned with a dense phase gas and then metal is recovered from the cleaned solids.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from International Patent Application Serial No. PCT / EP2006 / 003822, filed Apr. 25, 2006, which claims priority from European Patent Application No. 05009468.9, filed Apr. 29, 2005.BACKGROUND OF THE INVENTION[0002]The present invention relates to a method for treating of oil contaminated, metal-containing solids comprising a cleaning step wherein said oil is removed from said solids and a metal recovery step wherein metal is recovered from said cleaned solids.[0003]In the oil and petrochemical industry, large amounts of heterogeneous catalysts are employed. Often, metal salts are precipitated onto solid carriers, and the resulting product is used to facilitate or accelerate chemical reactions. As an example, silver oxide precipitated onto a solid ceramic such as aluminum dioxide or silicon dioxide catalyses the partial oxidation of ethylene to ethylene oxide. As a further example, metals and metal compounds...

AI Technical Summary

Benefits of technology

[0007]Thus, it is an object of the present invention to provide an improved method for treating of oil contaminated, metal-containing solids which ideally recovers the caloric energy of the contaminants such as oil and which ideally does not create additional toxic or corrosive or dangerous compounds.

[0008]Further, it is an object to provide a method for treating of oil contaminated, metal-containing solids which ideally provides a suitable raw material for further processes such as metal recovery, and which ideally is safe in operation, economic in investment and operational costs and environmentally benign.

Problems solved by technology

For various reasons such as coking or sintering of active phases during use, the lifetime of heterogeneous catalysts is limited.

Challenges to proper treatment are given by the toxicity of products remaining on the catalyst particles after use, the pyrophoric nature of the contaminants, such as oil or hydrocarbons, and the need to provide a suitable form of the cleaned catalysts for further processes, in particular metal recovery schemes.

However, various problems are associated with the state-of-the-art handling of oil-contaminated solids such as catalysts.

Incineration often proceeds without properly using the caloric energy of the contaminants.

Furthermore, incineration leads to the formation of toxic compounds such as polyaromatic compounds and additional coking.

Coking poses problems in later metal recovery schemes and additional waste problems.

Sulfur and nitrogen, typical components on spent catalysts, are converted during incineration to sulfuric acid respectively nitrous oxides / acids which give rise to corrosion problems.

Images