MANUFACTURE OF BASIC METALS # 23

Background

This case study illlustrates a new energy efficient copper smelting process which integrates the conventional operations of roasting, smelting and partial converting processes into one.

Cleaner Production Principle

New technology; Recovery, Reuse and Recycle

Cleaner Production Application

The Outokumpu flash smelting process combines the conventional operations of roasting, smelting and partial converting into one process. Preheated oxygen-enriched air is used to provide heat in such a manner that additional fuel is not required for the reactions to proceed. Copper concentrate is recovered from the slag and recycled through the smelter. The clean slag is sent for disposal. Heat and dust are recovered from the smelter gases producing dust for recycle to the smelter. Gaseous stream containing 10-30% of SO₂  is used for production of sulfuric acid. The matte is further treated in conventional converters to obtain blister copper.

Environmental and Economic Benefits

The main advantages of the Outokumpu process are the high sulfur recovery, the efficient energy utilization, and the flexible process in terms of accepting a varied feed material.

Energy consumption for the new technology is about 20 to 30% of that required by a conventional furnace. Operating costs are reduced to 61.0 cents/kg from 97.8 cents with conventional process. 50-80% of sulfur is recovered from the concentrate for use in sulfuric acid production, eliminating SO₂ emissions to the environment. Slag cleaning reduces copper content from 24% to less than 0.6% prior to disposal, eliminating problems due to liquid run-off from granulation pond.  

Constraints

None reported.

Contacts

Compendium on Low and Non-waste Technology, United Nations Economic and Social Counsel, "Primary Copper Production Using the Outokumpu Flash Furnace", Monograph ENV/WP.2/5/Add.115

Review Status

This case study was originally abstracted for the US EPA Pollution Prevention Information Clearinghouse. It underwent a UNEP IE funded technical review in 1994 for quality and completeness. It was edited for the ICPIC diskette in July 1995.

Subsequently the case study has undergone another technical review by Dr Prasad Modak at Environmental Management Centre, Mumbai, India, in September 1998.

height="6"