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FOR IMMEDIATE RELEASE: ( May 28, 1998)
SDSM& T RESEARCHERS PATENT PROCESS THAT RECOVERS PLATINUM FROM JUNK CAR PARTS
Demonstrating the “ real world” value of scientific research, South Dakota School of Mines & Technology scientists have developed a process that recycles junk car parts into platinum. Dr. Ken Han, SDSM& T Dean of the College of Materials Science & Engineering and Distinguished Professor of Metallurgical Engineering and Dr. Xinghui Meng, who received his Ph. D. from SDSM& T in Materials Engineering and Science, developed the patented process that recovers platinum group metals from used automobile catalytic converters in an environmentally friendly and metallurgically efficient manner.
The South Dakota Governor’s Office of Economic Development provided the initial funding for the research project. SDSM& T holds two patents on the new process that are based on two earlier patents for extracting gold from ore without using cyanide.
Platinum group metals, which are considered strategic metals, include platinum, iridium, osmium, palladium, rhodium and ruthenium. These metals are used in multiple ways by various industries including the automobile, electrical and electronic, dental and medical, petroleum refining, and numerous chemical industries. The United States currently imports more than 50% of its platinum group metals ( PGM) supply, with major foreign sources being Russia and South Africa. A secondary source— scrap of ceramics/ glass, electrical components and auto- exhaust catalysts— is becoming increasingly important, especially in the United States. If all platinum- group metals were to be recovered and recycled from available scrap, such as automobile catalytic converters, the U. S. would become the world’s largest platinum group metals producing country. Approximately 45 million automobiles are scrapped worldwide every year, more than 15 million of which are junked in the U. S. Over 70% of the catalytic converters from these junked automobiles are currently exported, primarily because no large scale, environmentally safe and economical process is available in this country.
In general there are three types of automobile catalytic converters in terms of the PGM content. Grade 1 consists of 2200 parts per million ( ppm) of platinum ( Pt), 200 ppm of palladium ( Pd) and 300 ppm of rhodium ( Rd). Grade 2 has 1000 ppm Pt, 200 ppm Pd, and 100 ppm Rd; while Grade 3 consists of 875 ppm Pt, 250 ppm Pd, and 30 ppm Rd.
On average a metric ton of each catalytic converter grade contains the following PGM values: Grade 1 - $ 34,588; Grade 2 - $ 16,023; and Grade 3 - $ 13,667. These values are based on March 13, 1998, metals market prices of platinum at $ 392/ oz., palladium at $ 264/ oz. and rhodium at $ 535/ oz.
With approximately 700 catalytic converters producing one metric ton of materials, over 21,400 metric tons could be obtained from the15 million autos that are junked annually in the United States. With a current average value of $ 21,426 per metric ton for the three grade types ( based on March 13, 1998 prices), over $ 450 million worth of platinum- grade metals could be recovered from these used catalytic converters.
Because the platinum group metals are very inert, their extraction using the conventional technology is very expensive— approximately $ 600 per ton of catalytic converters on chemical consumption alone. The process suffers from severe acid corrosion problems and also from using a high percentage of the acidic reagant, the solution used in a chemical reaction.
The new technology developed by SDSM& T researchers is based on halogen salts in a confined vessel in the presence of ammonium salts, ammonia and oxygen. The major advantage of this new technology over existing technologies is that the halogen- salt process is very effective in recovering rhodium as well as the other platinum group metals. The SDSM& T process produces very clean solid residue and continuously recycles the chemicals and liquid in the system, thus negating the need to dispose of any liquid or gas. In addition to being much more environmentally friendly, this new process has much lower operating costs – only 1/ 3 as much as the existing technologies.
The SDSM& T process works not only for extracting PGM from catalytic converters and petroleum refining catalysts, but also for extracting gold from refractory gold ores and PGM from platinum bearing ores. The process is an extension of another process developed by SDSM& T for extracting refractory gold ores using ammonia.
After SDSM& T researchers discovered the process, additional testing with a high- temperature reactor was needed for a feasibility study. Former SDSM& T Vice President Dr. Bill Hughes ( EE 49), President of Dakota Alpha Inc., a Rapid City based engineering firm, and SDSM& T jointly built a titanium reactor that is capable of handling 25kg of catalysts per batch. Test results to date show better than 95% recovery of PGM from automobile catalytic converters and 98% recovery from refinery spent catalysts.
Although the initial test results have been very promising, additional worth of equipment and testing are needed to further fine- tune the process for use by the private sector. Companies or individuals interested in participating in further research and development of this process can contact Dr. Han at 394- 2342 or Dr. Hughes, Dakota Alpha Inc., at 348- 7665.
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