This paper presents possibility of removing platinum from the used catalytic converters applying copper as a metal collector in pyrometallurgical methods. The catalytic converter carrier was grinded and melted with copper. During the research obtained Cu-Pt alloy was casted as an anode. Such anode was electrically refined in order to recover platinum. Obtained results were discussed

A. Fornalczyk

M. Saternus

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219METALURGIJA 52 (2013) 2, 219-222A. FORNALCZYK, M. SATERNUSPLATINUM RECOVERY FROM USED AUTO CATALYTIC CONVERTERS IN ELECTROREFINING PROCESSReceived – Prispjelo: 2012-06-04Accepted – Prihvaćeno: 2012-10-10Preliminary Note – Prethodno priopćenje ISSN 0543-5846METABK 52(2) 219-222 (2013)UDC – UDK 669.231:661.69.004.86:66.067=111A. Fornalczyk, M. Saternus, Department of Metallurgy, Silesian Univer-sity of Technology, Katowice, PolandThis paper presents possibility of removing platinum from the used catalytic converters applying copper as a metal collector in pyrometallurgical methods. The catalytic converter carrier was grinded and melted with copper. During the research obtained Cu-Pt alloy was casted as an anode . Such anode was elec trically refi ned in or der to recover platinum. Obtained results were discussed.Key words: Precious Group Metals (PGM), metal recovery, used auto catalytic converters, electrorefi ning.INTRODUCTIONAuto catalytic converter is a part and parcel of every car exhaust system, the main aim of which is to decrease the exhaust gases emission to the atmosphere. Like any other catalytic converter, it is used to increase the proc-ess. Catalytic material is not changing that means it is not active in the reactions or processes. Currently cata-lytic converters are practically applied in all kinds of produced vehicles. The auto catalytic converter (see Figure 1) consists of steel or ceramic shell containing the carrier of honeycomb structure covered by the PGM, especially platinum, palladium and rhodium. Such con-struction increases the active surface, namely the con-tact zone of catalytic substances (Pt, Pd, Rh) with ex-haust gases, which ﬂ ow through the channels. TWC (Three-Way Catalyst) is a modern catalytic converter in which three reactions take place simultaneousely: two oxidation reactions of CO to CO2, HC to H2O, and re-duction of NOX to N2. Consequently, substances inert to the environment are obtained in the outlet of auto cata-lytic converter.PGM metals recovery from used auto catalytic convert-ers, becomes very important, taking into consideration the economical management of natural resources and energy. Additionally, there is less waste deposited in the storage area. The content of PGM metals in auto cata-lytic converetr depends on the construction of catalytic converter, its use and the manufacturer (average about 2 grams of PGM metals).METHODS OF PLATINUM RECOVERYTaking into account scarceness of the natural re-source occurance and energy consumption during their output, PGM metals recovery seems to become neces-sary both from economic and ecological point of view. So, recycling process makes a contribution to the natu-ral resources protection and also the stabilization of PGM metals prices (limits the metal price increase caused by the growing demand of a car industry). Reuse of PGM metals recovered in such a way does not re-quire high costs. Whereas, the considerable amount of used auto catalytic converters, that are scrapped every year makes the PGM metals recovery very proﬁ table.The ﬁ st step to recover PGM metals and especially platinum from used auto catalytic converters is to col-lect and then dismantle them. After these operations catalytic converter carriers are milled and also homog-enized. Then chemical analysis must be performed in order to check the level of platinum and other precious metals. If the platinum level is lower than 30 %, the thickening operation is applied. This stage includes in-cineration, hydrometallurgical and pyrometallurgical processes [1-7]. The last two methods can be combined. As a result, the high level of PGM metals recovery can be obtained. In such technologies many indirect opera-tions are used to obtain pure metal. Figure 2 presents the hydrometallurgical and pyrometallurgical methods used for the treatment of catalytic converter carriers.Figure 1 Scheme of auto catalytic converterRapid developement of motorization and the huge amount of used cars are the reasons why there is a ne-cessity to lead rational management of waste coming from such sector. Possibility of reusing material, that is 220  METALURGIJA 52 (2013) 2, 219-222A. FORNALCZYK et al.: PLATINUM RECOVERY FROM USED AUTO CATALYTIC CONVERTERS…The next stage of PGM metals recovery is to solve and separate precious metals and purify them. Puriﬁ ca-tion allows to obtain metals of very high purity. This stage, however, requires a lot of energy and also gener-ates many chemical compounds dangerous to the envi-ronment. Processes that can be used in PGM metals puriﬁ cation are: calcinations, ion exchange, solvent ex-traction, hydrolysis, reduction and oxidation processes, as well as precipitation [8-11].None of pyro- and hydrometallurgical methods is an universal method that can be used to recover PGM met-als from all type of used auto catalytic converters. Both methods have some disadvantages:pyrometallurgical methods require special equip-• ment, to reach the desired temperature, and they are not only expensive but also highly energy consum-ing;hydrometallurgical methods requires to solve the • problem of harmful waste solutions generated dur-ing the process.Melting method belongs to one of the simplest pyro-metallurgical methods. It uses a metal collector to gath-er platinum and other PGM metals. Different metals such as calcium, zinc, magnesium, cadmium, lead and copper can be used as a metal collector. These metals are selected taking into account the solubility of plati-num.EXPERIMENTAL PROCEDUREThe paper presents the research concerning the pos-sibility of platinum recovery from used auto catalytic converters applying copper as a metal-collector. The re-search was carried out in the laboratory of the Metallurgy Department at the Silesian University of Technology. The research was divided into two stages (see Figure 3).Material for the research (carriers of used auto cata-lytic converters) came from different cars. The analysis Figure 2 Available processes applied in PGM recovery from used auto catalytic convertersFigure 3  Procedure taking palce during  platinum recovery from used auto catalytic converters in electrorefi ning process.221METALURGIJA 52 (2013) 2, 219-222A. FORNALCZYK et al.: PLATINUM RECOVERY FROM USED AUTO CATALYTIC CONVERTERS…of platinum contents in catalytic converter carrier and in the samples was conducted in the Institute of Nonfer-rous Metals in Gliwice. Spectrometer and ICP method were used. The analysis of ceramic carriers used in the tests indicated the difference in their platinum contents. The average content was between 0,16 and 0,32 %. As a metal–collector, copper M0B with the purity 99,99 % was used.Stage I. The main aim of this stage was to melt the grinded catalytic converter carrier with copper. It was done in Elkon inductive furnace. During the melting process platinum went to copper (because its melting temperature is higher than that of the metal-collector) and the ceramic carrier created the slag. In the furnace, neutral atmosphere was kept by blown argon. Table 1 presents parameters of the test carried out in stage I of the research.Stage II. The obtained copper with platinum sepa-rated from slag was melted and casted in the form of anode (see Figure 4). It was placed in electrolytic cell and then electroreﬁ ned. Table 2 presents the main processing parameters, whereas Figure 5 shows the test stand.RESULTS OF THE RESEARCHAs a result of the electroreﬁ ning process the slime (see Figure 6) with platinum and other PGM metals was obtained. Table 3 presents the analysis of that slime. Pure copper was captured on the cathode, so it can be used again in the process.Table 1 Parameters of the test in stage I of researchParameters of the testsFurnace inductive furnace (ELKON)Temperature 1 550 °CTime of process 5 400 sArgon blow 50 dm3∙h-1Cooling sample was cooled with the furnaceMass of carrier 600 gMass of copper 1 270 gTable 2 Processing parameters of stage II of researchProcessing parametersNoCCurrent density/ A∙m-2Time/ hMass of anode/ gElectrolyte/g∙dm-3Cu H2SO41 100 70 1 284 45 2002 100 40 1 061 45 200Table 3 Results of electrolytic refi ning process Chemical analysis and effi  ciency of the process NoPt contentEffi  cienc yin carrier in anode in slime1 0,26% 0,001% 0,15% 84 %2 0,26% 0,001% 0,13% 80 %Figure 4 Obtained copper sample with platinumFigure 5 Scheme of test stand used for the researchFigure 6 View of the obtained slimeCONCLUSIONSNowadays the regulations concerning emission of fumes are very strict. These regulations are the conse-quence of constantly growing road transport and the increase of air pollution. To prevent pollution, every new car has to be equipped with the catalytic converter. The lifetime of auto catalytic converters is limited. Their duration in which the effectiveness is no smaller than 75 % is estimated for 160 000 km.222  METALURGIJA 52 (2013) 2, 219-222A. FORNALCZYK et al.: PLATINUM RECOVERY FROM USED AUTO CATALYTIC CONVERTERS…That is why, used auto catalytic converters have be-come the valuable source of platinum and PGM metals. At present the most important is to ﬁ nd simple method to recover these metals. The melting method using es-pecially copper as a metal collector seems to fulﬁ l such demand. The efﬁ ciency of recovered platinum is very promising, so the research will be continued. However, there are still many hydrometallurgical processes to go through in order to obtain pure platinum and other pre-cious metals.AcknowledgementsFinancial support from Polish Ministry of Science and Higher Education is acknowledged (contract No N N508 6255 40).References[1] Y. Kayanuma, T. Okabe, M. Maeda, Metallurgical and Ma-terial Transactions, 35B (2004) 5, 817-824.[2] J.S. Yoo, Catalyst Today, 44 (1998) 1, 27-46.[3] R. Rao, Resource recovery and recycling from metallurgi-cal wastes, Oxford University, Elsevier, 2006.[4] M. Benson, C.R. Bennett, J.E. Harry, Conservation and Recycling, 31 (2000) 1, 1-7.[5] K. Byung-Su, L. Jae-chun, S. Seung-Pil, JOM, 56 (2004) 12, 55-58.[6] A. Fornalczyk, M. Saternus, Precious metals recovery from the used auto catalytic converters, International Symposium on Liquid Metal Processing and Casting, (2009), 381-387.[7] A. Fornalczyk, M Saternus, Metalurgija, 50 (2011) 4, 261-264.[8] J. Chen, K. Huang, Hydrometallurgy, 82 (2006) 3-4, 164-171.[9] T.N. Angelidis, Topics in Catalysis, 16/17(2001) 1-4, 419-423.[10] B. Pospiech, Physicochem. Probl. Miner. Process, 48 (2012) 1, 239-246.[11] G. Siwiec, J. Willner, Metalurgija, 48 (2009) 2, 75-77.Note:  M. Kingsford-Golinowska is responsible person for English language.

Platinum recovery from used auto catalytic converters in electrorefining process

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