INNOVATIVE SOLUTIONS IN COPPER PRODUCTION LINES

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1 INNOVATIVE SOLUTIONS IN COPPER PRODUCTION LINES R. Degel*, H. Joubert SMS group GmbH Eduard Schloemann Strasse 4 Düsseldorf, Germany rolf.degel@sms-group.com A. Filzwieser PolyMet Solutions GmbH Peter Tunner Str Leoben, Austria I. Filzwieser, M.B. Hanel Mettop GmbH Peter Tunner Str Leoben, Austria ABSTRACT This paper highlights innovation for complete copper production route starting with the primary smelting of concentrate and ending with the electrolysis. Mettop and SMS formed a Joint Venture in May 2016 with the target to identify and design innovative solutions for the primary copper production lines as well as for non-ferrous metals. The business model of PolyMet Solutions as well as the complete product portfolio will be presented. The paper will explain potential improvements in primary smelting of copper concentrate with a new type of primary smelter (PolySmelt) and will compare it with conventional technologies. An introduction to potential improvements in TLS (Top Lance System) type smelters will be made. The ILTEC cooled tuyeres or plugs will optimize the process and change the campaign life of the anode furnaces and Peirce Smith converter significant. Finally the latest status in slag cleaning will be shown. It is the target allowing to lower the remaining copper content in the discard slag below 0.3 % with an innovative two-step solution. Mettop has developed together with Montanwerke Brixlegg AG a Parallel Flow Device (PFD) allowing a current efficiency above 98 % at a current density of 420 A/m², which is a new milestone in copper electrolysis.

2 INTRODUCTION Non-ferrous metals move the world. All modern industrial sectors would not exist without the presence of these valuable materials. Non-ferrous metals are essential for the functionality of any modern articles of the daily use such as smart phones, tablets and computers. During the past years almost all metal prices are under pressure [1] and therefore competitive solutions are becoming most important to keep the market position stable. Such situations also bear opportunities for companies in the non-ferrous metals business. SMS and Mettop founded a joint venture - PolyMet Solutions GmbH - which serve producers in the non-ferrous metals industry with the target to develop new innovative and especially profitable solutions for the metals producing industry. It mainly includes the primary pyrometallurgical process route, where metals are processed out of ore/concentrates. Per definition, the term secondary route mainly describes metal processing out of secondary metal sources. Within the Joint Venture between Mettop and SMS, the engineering of complete process routes is possible. This includes the overall design of refractory concepts in 3D, refractory supply, engineering, equipment supply and commissioning of the plant starting from the raw materials and smelting metallurgy, through shaping and up to the finishing. The SMS group is specialized in executing challenging projects whereas Mettop supplies innovative components such as a new safe because of water free cooling system (ILTEC Technology), new electrolysis and intelligent vessel cooling concepts. If requested by our customers, SMS can also offer support in project financing. With this set up, a large variety of services and supplies starting from small feasibility studies up to complete turnkey solutions for sub-units as well as for green field and brown field plants can be offered and executed. PROCESS The complete understanding of the process is most essential for designing of reliable and efficient metallurgical plants. It allows the correct dimensioning of pyrometallurgical vessels for new non-ferrous metals plants. The right process definitions will results into a more profitable plant mainly due to: Higher efficiency Lower energy consumption Higher productivity and yield Longer furnace campaign life Improved safety Lower maintenance and shut down costs Furthermore it provides the fundamental data and information for all related auxiliaries and surrounding units such as off-gas system, raw material- and product handling, cooling systems, etc.

3 REFRACTORY Refractories have a major influence on the OPEX and therefore of the profitability of any smelting plant [2]. The initial refractory material cost is significant, but the full life value including loss of production and unexpected failures can be even more significant. The correct understanding and definition of the process is most important to provide an optimized lining concept. Achieving the best whole of life value requires a fully integrated management system. PolyMet Solutions engineers all refractory related designs in 3D. The illustrations allow a much better visualization of the solution and avoid design mismatches. Thermal expansion calculation is more accurate and due to the installation support tools in 3D allows a faster installation at higher quality. Additionally, the costs and time for necessary brick cutting on site are minimized. Figure 1 3D engineering of a holding furnace COOLING In most metallurgical vessels the lining wear is controlled by an additional cooling method in certain areas of the furnace. Over the past decades SMS and Mettop developed numerous cooling systems for almost all pyro-metallurgical processes in the non-ferrous industry as well as for the iron and steel industry. Especially in highly stressed areas e.g. locations facing abrasions by the off-gas or bath turbulences, tap hole areas, aggressive slag, changing slag compositions, thermal cycling or high temperature levels intelligent solutions are required. Various vessel cooling systems utilizing air cooling, spray cooling or cooling with internal copper elements. The following list gives an overview about the available cooling solutions: CFM (composite furnace modular) cooling solutions Copper staves for shaft furnaces Plate coolers Finger coolers Tailor made systems

4 For example the CFM cooling allows a safe operation under extreme conditions and can handle, depending on the design, heat fluxes of > 400 kw/m 2. The heat flux is to a certain extent adjustable by the design of the element [3]. Figure 2 CFM (Composite Furnace Module) cooling element FURNACE INTEGRITY The vessel integrity ensures a reliable and safe furnace operation as well as a long furnace campaign life. Process know-how, operation practice know-how, expertise in refractory and furnace cooling as well as furnace design is the key figures for increased furnace integrity. Furnace Integrity Refractory Figure 3 Aspects furnace integrity Using modern software packages for thermodynamic calculations, CFD (Computational Fluid dynamics) calculations and FEM (Finite Element Method) calculations and combining calculations with real data from industrial plants give the basis for our sound solutions.

5 COPPER ROUTES The conversion of copper and nickel consists of a series of chemical, physical, and electrochemical processes. Methods have evolved and vary by the nature of ore source, local environmental regulations and other factors. Basically is has to be distinguished between primary and secondary process route. Copper recycling is executed by pyro-metallurgical processes. Following the flow in primary copper and nickel production, PolyMet Solutions provides innovative solutions for all process steps starting from the primary smelting of the ore/concentrate and finishing with the electrolysis based on the Mettop-BRX- Technology. (cooling and purging by Mettop) (cooling and purging by Mettop) Figure 4 Copper process route The choice of the suitable secondary copper process route mainly depends on the available scrap quality. All necessary units for an efficient copper production via the secondary route are covered by the Joint Venture and partners. In particular the gas treatment becomes most important, because the input material varies significantly in particular the content of organic components. Here advanced gas cleaning solutions are essential to capture components such as mercury, brome, fluorine and chlorine. PRIMARY SMELTERS PolyMet Solutions develops an improved primary smelter called PolySmelt for non-ferrous metals. Basically PolyMet Solutions takes the existing reactors as a basis and introduces innovative changes improving the efficiency, operation and lifetime. The PolySmelt process is based on industrially proven technologies with certain improvements. PolySmelt represents a reliable and low cost alternative compared to todays applied flash furnaces and TSL-systems.

6 Figure 5 - Illustration of a PolySmelt reactor for copper concentrate smelting Basically the concentrate is fed in a rectangular furnace through an opening in the furnace roof. Matte and slag are tapped in the opposite direction separately through siphons on the side of the furnace. The main advantages are: High speed tuyeres providing a good turbulence for rapid reactions in the reactor Improved lining and cooling concept for long furnace life time Robust low cost solution due to rectangular furnace design principle TSL-systems are in use since decades for the production of copper and other nonferrous metals. PolyMet Solutions sees also room for improvement of existing and new units. Newly installed systems can be equipped with modern high speed burners providing faster and rapid reactions in the reactor and replacing the conventional selfconsuming top lance. Improved side wall cooling and lining concept minimizing the hearth and sidewall wear. CONVERTING PolyConvert is the logical next step in converting by implementing improvements using the convention Peirce Smith converter. This reactor type is still the dominant process for the production of blister copper. It can be also applied in the nickel and PGM production process line. The converting is done in slag blow stage and in separate final converting phases. PolyMet Solutions added numerous features improving in particular the process efficiency as well as the availability and lifetime of the vessel: Improved lining concept in the tuyeres area and mouth area ILTEC cooling of the under bath tuyeres for a significant prolongation of the campaign life (up to 1 year) higher productivity with lower OPEX Sub-sonic injection through tuyeres resulting in increased productivity and reduced offgas volume and finally smaller gas treatment plants are needed Optimized automation

7 Figure 6 Under bath ILTEC-cooled tuyers for a Peirce Smith converter The extensive refractory wear on under-bath tuyeres is the main reason for taking a PSC out of service for rebuild. By cooling the tuyeres with ionic liquid, it is expected to prolong the life-time to 1 year. The concept is fully designed and will be installed in a Peirce-Smith in Europe. PolyMet Solutions is also working on a continuous converting aggregate as an alternative to the Peirce Smith converter. TBRC The TBRC (Top Blown Rotating Converter) was developed in the 30 s to smelt and converts numerous primary and secondary raw materials for the winning of copper, nickel, lead/zinc, tin and precious metals. Figure 7 TBRC as installed in Germany Especially in the recycling area it is also used for the smelting of electronic waste. The batch process is carried out in the rotating vessel where heating and converting is done by a central burner and a central cooled lance. SMS supplied over the past decades

8 more than 40 of these units. Within the Joint Venture we also provide the process comprising of these units: High rotating speed up to 20 r/min Multiple lance and burner system for improved process efficiency Intelligent refractory lining concept Mechanically robust vessel Optionally exchange vessel can be offered SLAG CLEANING PROCESS The electric cleaning furnace is mainly used in the nickel, copper and PGM industry for the recovery of precious metals out of the slag. The first units were installed by SMS in the 50 s and since then more than 40 units were supplied by SMS. Depending on the slag properties rectangular solutions or circular solutions can be applied. PolyMet Solutions is also involved in the refractory lining optimization. For our clients, we can state the following advantage by using a SMS slag cleaning furnace: Outstanding reference track record for rectangular and circular slag cleaning furnaces Highest recovery rate of precious metals Best available electrode column system using either pre-baked or Soederberg type electrodes Low investment and operational costs Refractory lining and quality concept optimization Figure 8 Rectangular slag cleaning furnace Over the past decades SMS worked intensively on the further improvement of slag cleaning efficiency [4-6]. First attempt of applying an electromagnetic stirring reactor were promising and showed already results of approx. < 0.5 % remaining copper

9 content in the discard slag. Currently SMS even further developed the idea of a separate stirring for improved coagulation of the copper droplets. The new envisioned process consists of a tailor made stirring unit utilizing natural gas and carbon as a stirring agent. The slag is then charged into a conventional rectangular slag cleaning unit. With this set up, copper content of < 0.3 % are achievable. Figure 9 Previous test in the slag stirring reactor ANODE FURNACES The anode furnace is the main technology for converting of blister copper into anode copper. The vessel is a horizontal cylinder, which rotates in both directions. In the first process step, sulfur is removed by oxidation and the second step, the oxygen in the copper is removed by reducing agents. Fluxes and additives are charged during the operation reducing impurities such as lead and arsenic. Over the last years, in particular the operation of the vessel as well as the gas purging philosophy has been improved. Furthermore our lining principle in the plug and mouth area is improved prolonging the overall refractory campaign life. Additionally the design of the charging mouth and off-gas outlet minimizes process fugitive gases polluting the furnace building. The following main features are included in the PolyMet Solution system: Improved refractory lining concept in the tuyere, mouth and off-gas offtake area maximizing the refractory lining lifetime Improved process (logistics, sequencing etc.) Optimized purging operation by operator training sessions Advances automation and process control

10 Reduction in process time Reduction in fuel usage and increased productivity Figure 10 Gas tight charging mouth of an anode furnace ANODE CASTING, GRANULATION SYSTEMS Anode casting wheels from SMS ensure high availability and reliable operation. Comfortable operation and maintenance together with low process costs form the basis for cost-effective anode production at a high level of quality. Main features: Close weight tolerances of the anodes Reduced process costs thanks to dynamic control of the mold temperature Sturdy technology durable and with minimum maintenance Reduced scrap rate leading to increased productivity TANK HOUSE TECHNOLOGY Achieving more than 400 A/m²: To increase the productivity of a copper tank house, the current efficiency and/or current density needs to be increased. Mettop has developed together with Montanwerke Brixlegg AG a Parallel Flow Device (PFD), which introduces the fresh electrolyte between each pair of electrodes. The device directs the fresh electrolyte in an upwards flow on the surface of the cathode, which enhances the already existing flow resulting from natural convection. Therefore, the settlement of the anode slime is not influenced by using the METTOP-BRX Technology.

11 Figure 11 METTOP-BRX Technology as operating in Xianguang, China Due to the improved flow pattern up to 50 % increase in current density is achieved, even at a high current efficiency, while still maintaining good cathode quality or even improving it. The key for this new record in current density is the parallel flow pattern of the electrolyte, as shown above. This principle is currently in operation since 2011 in China [7]. Current efficiency above 98 % at a current density of 420 A/m² had been achieved. The quality of the cathode is from the chemical and physical properties outstanding. The benefits of the METTOP-BRX Technology are obvious: Much smaller footprint of a tankhouse at the same capacity compared to a conventional system Decreased CAPEX and OPEX Reduced inventory costs (the inventory costs can be decreased by 50 Mio. Euro comparing a 400,000 t tankhouse by using high current density technology) Mettop will supply the patented key equipment, SMS can supply complementary components such as cranes, machinery, auxiliaries. An entire tankhouse can be offered. CONCLUSION AND OUTLOOK Mettop and SMS formed a Joint Venture in May 2016 with the target to work out innovative solutions on the primary copper production lines as well as for non-ferrous metals. The new business set up offers innovation for complete copper lines starting with the primary smelting of concentrate and ending with the electrolysis. A new type of rectangular shaped primary smelter (PolySmelt) as well as potential improvements in various types of smelters will widen the product portfolio for our clients in the nonferrous metals business. The new type of ILTEC-based cooler tuyeres or plugs will

12 optimize the process and change the campaign life of anode furnaces and Pierce Smith converter significant. Finally PolyMet Solutions is convinced that a target of 0.3 % of the remaining copper content in the discard slag is feasible with an innovative two-step solution. Mettop has developed together with Montanwerke Brixlegg AG a Parallel Flow Device (PFD) allowing a current efficiency above 98 % at a current density of 420 A/m², which is a new milestone in copper electrolysis. REFERENCES [1] - Homepage of the International Copper Study Group, visited on 15 th May 2016 [2] S. Ruhs, A.Filzwieser, M.B. Hanel, I. Filzwieser, S. Wallner: Furnace Integrity Mettop s Holistic Approach to Face Todays Challanges, Copper2016, November, Kobe, Japan, 2016 [3] Kyllo, A.K., A. Filzwieser and N.B.Gray: Composite Furnace Models Background and Update, Proceedings of the EMC, June, Düsseldorf, Germany, 2007 [4] Warczok, A., Degel, R., Kunze, J., Oterdoom: Rectangular furnace design, furnace modelling slag washing machine, EMC 2007, April 2007 in Düsseldorf, Proceedings, 2007 [5] Warczok, A., Riveros, T., Degel, R., Kunze, J., Oterdoom: Slag cleaning in circular and rectangular furnaces, Proceedings of the Sixth International Copper- Cobre Conference, August 25-30, Toronto, Ontario, Canada, 2007 [6] Warczok, A., Riveros, G. Marin, T., Degel, R., Kunze, J., Oterdoom, H., Wuebbels, T.: Intensive electrodynamic slag cleaning, Proceedings of the Sixth International Copper 2007 Conference, August 25-30, Toronto, Ontario, Canada, 2007 [7] Filzwieser A., Filzwieser I., Konetschnik S., Anzinger A.: Cost comparison between a conventional ER tankhouse and a high current density ER tankhouse using the Mettop-BRX Technology, Proceedings of the Eighth International Copper Conference, December 1-4, Santiago, Chile, 2013