1997 TMS Annual Meeting: Wednesday Abstracts

THE INCREASING IMPORTANCE OF SECONDARIES & RESIDUES IN PRIMARY & SECONDARY Cu/Ni SMELTING: Its Technical, Economic and Environmental Effects

Session Chairpersons: N.L. Piret, Piret & Stolberg Partners, Im Licht 12, D-47279 Duisburg, Germany; Paul B. Queneau, Hazen Research, Inc. 4601 Indiana St., Golden, CO 80403

8:30 am INVITED

WASTE DISPOSAL BY RESIDUE RECYCLING AT KGHM POLSKA MIEDZ SA: Helena Byrdziak, Jerzy Dobrzanski, Jan Garbaczewski, Janusz Piatkowski, KGHM Polska Miedz SA, P-59300 Lubin, Ul. Sklodowskiej 48, Poland

KGHM Polska Miedz SA, existing since seventies, operates three underground mines and three smelters with local production of over 400,000 mtpy of electrolytic copper. Its impact on the environment, very serious in the past, has been gradually reduced, In general, recently emission into the air and water has been put under control. Nowadays tailings and residues disposal has turned to be the subject of first environmental importance. The total bulk of tailings is enormous as copper ore contains only about 2% of copper, so 98% of extracted material must be disposed gradually in each step of technology. The main Streams are tailings from the flotation, slags, captured dust from dedusting systems and gaseous compounds like SO2 and CO. Much effort has already been done and is still being done to utilize them for by-products production or to dispose them within the process by recycling. The most effective measures taken up so far and present activity towards waste disposal are presented.

9:00 am

RECYCLING OF PRINTED CIRCUIT BOARDS BY SMELTING WITH OXIDIZING/REDUCING TOP BLOWING PROCESS: Andrea Bernardes, Isrun Bohlinger, Diosnel Rodriguez, Wolfgang Wuth, Technical University Berlin, Institute of Metalllurgy, Strabe des 17. Juni 135, D-10623 Berlin, Germany

Printed circuit boards (PCBs) of varying compositions have been converted by incineration, followed by smelting to an environmentally stable slag and a copper-nickel-tin alloy, containing the precious metals. The environmentally compatibility of the slag was established according to the German Standard DIN 38414, Part 4. The concentration of toxic elements in the lixiviates was found to be lower than the threshold value for drinking water (CE-Standards). In each experiment the charge was 500 g scrap from PCBs and 100 g flux. The products were a king of mullite slag, poor in iron, which was recirculated, and an alloy containing up to 0.3% gold. With a burner the process gas was combusted without soot formation and the generated mixed zinc-lead oxide fume containing silver was separated as flue dust.

9:30 am INVITED

COPPER FROM COPPER BEARING SCRAP, A MOVING TARGET: Albert W. Spitz, Robert A. Spitz, Michael Saltzburg, 560 Bedford St., B-12, Abington, MA 02351

Profitably recovering copper and precious metals from copper bearing scrap is a demanding and frustrating combination of art, science and economics. With fluctuating markets, varying raw materials and increasingly stringent environmental regulations requiring process revisions, practically everything is changing. The volatile copper market constantly shifts the percentage of copper in the scrap that can be economically processed. Scrap that has value one day may incur a disposal cost the following day. Also with less copper in the scrap, more residuals, slag, fume, etc. are generated which frequently present disposal problems and infrequently generate income. The ever increasing amounts of electronic scrap add value to the copper produced by virtue of the precious metals present. Printed circuit board materials create more slag and organic off gases which must be treated. Finally, the emphasis on reducing emissions of organics and other metals, especially lead, is a continuing challenge. Stack gases, fugitive emissions and ambient air quality all demand constant surveillance.

10:00 am BREAK

10:30 am

CHANGES IN THE DUST HANDLING SYSTEM AT HUDSON BAY MINING & SMELTING CO., LTD: Keith McTaggart, Hudson Bay Mining & Smelting Co., Ltd, P.O. Box 1500, Flin Flon, Manitoba R&A 1N9, Canada

The waste gas cleaning system of the Hudson Bay Mining & Smelting copper smelter in Flin Flon, MB, consists of an electrostatic precipitator followed by a baghouse. These units collect the copper and zinc bearing dusts, respectively, from the gas streams of the reberberatory furnace and Pierce-Smith converting furnaces. A process change in 1993 led to the rapid destruction of the existing baghouse fibreglass filter bags, shortening their life-span from 15 to 3 months. A decision was made in September 1994 to replace this type of filter media with an expanded polytetrafluoroethylene (PTFE) membrane filter supplied by W.L. Gore Associates, Inc. Following the original installation a dramatic increase in dust capture was observed, however high pressure drops across the filter material lead to decreased flow through the off-gas handling system, limiting ventilation of the process. This increase in pressure drop across the PTFE bags was a function of the PTFE material and the inability of the baghouse shaker system to release the dust layer from the PTFE bags. Recently acoustic horns have been tested as a replacement to the shaker cleaning mechanism. Preliminary results indicate a dramatic reduction in pressure drop across the bags and a subsequent increase in process ventilation. This allows for fewer production interruptions caused by fugitive process emissions. The final acoustic horn results will be presented.

11:00 am INVITED

THE ECONOMIC AND ENVIRONMENTAL BENEFITS OF AUSMELT TECHNOLGY IN SECONDARY COPPER SMELTING AND CONVERTING: Edward N. Mounsey, Ausmelt Ltd., 12 Kitchen Rd., Dandenong 3175, Victoria, Australia; Norbert L. Piret, Piret & Stolberg Partners, Im Licht 12, D-47279 Duisburg, Germany

The requirements to smelt secondary copper more economically, to process a wide range of materials with large fluctuation in size and composition and to cope with the increasingly stringent environmental constraints have put considerable pressure on existing conventional secondary copper smelters. The Top Submerged Lance (TSL) process, developed and commercialized by Ausmelt Ltd over the past 20 years, offers a low cost technology, which is particularly suitable for the treatment of copper-bearing scrap and residues, because of its low investment, use of cheap fuel and reductant, high rate of recovery of metals and low slag losses, potential use of oxygen, high flexibility with regard to feed material, applicability to high and low throughputs, absence of dioxins in the process gas, simplicity of handling of feed, process gas and slags. This presentation outlines the application of Ausmelt technology in secondary copper smelting, producing converter grade copper ready for anode furnacing, both for a new installation and for a retrofit of the smelting or converting stage of an existing smelter. The economic and environmental benefits of its application are highlighted.

11:30 am

METALLURGICAL UTILISATION OF REUSABLE PRODUCTS FROM THE RECYCLING INDUSTRY IN A SECONDARY COPPER SMELTER: Andreas Nolte, Huttenwerke Kayser AG (HK) Postfach 15 60, D-44505, Lunen, Germany

This paper includes a comprehensive report about the metallurgical utilisation of reusable products from the electronic scrap recycling, car scrapping industry, used glasses and various waste products such as for example slimes and flue dusts in a secondary copper smelter. Dependent on the copper content, the existing copper compound and further aspects of the additional material content, the materials are treated in reducing and oxidizing furnace operations. HK's pyro- and hydrometallurgical processes, blast furnaces, converters, anode furnaces, tin lead alloy plant and tankhouse will be explained. The treated reusable products are structured according to the origin of the materials and then presented in quantity and quality balances. Processing methods, processable quantities and required qualities of the reusable products are described. The utilization degree of the most important metals (copper, tin lead and zinc) is described with graphics. The report is rounded by information on operating licence according to the emission protection regulations of the Federal Republic of Germany and informations concerning supply and contracts.