Recovering Precious Metals From Spent Catalysts
With declining fossil fuel consumption, Middle East refiners
seek profits from other sources.
By Kevin M. Beirne, Sabin Metal Corporation, East Hampton NY USA
In round numbers, there are over 100 Gulf-region hydrocarbon refiners. These organizations are state owned, joint ventures, original concessions, or independent, foreign owned businesses. Mideast refineries convert more than eleven billion barrels per year of crude oil into commercially marketable products. While they compete against each other in one form or another, they also share a common trait: that is, the consumption of thousands of tons of precious metal-bearing catalysts used to facilitate and/or speed hydrogenation during the refining process, and also for controlling end-of-pipe process discharges to comply with pollution abatement regulations. The precious metals in these catalysts are known as “PGMs”, or Platinum Group Metals that include platinum, palladium, rhodium, and ruthenium; rhenium, while not considered a PGM, is also a valuable precious metal and is often present in hydrocarbon processing catalysts along with gold or silver. PGM-bearing catalysts are typically employed on substrates (carriers) such as soluble and insoluble alumina, silica alumina, zeolite, or carbon supports (Figure 1). Whatever their composition, eventually, due to the harsh environments which contaminate them with carbon, sulfur, volatile organics, moisture, or other impurities, the catalysts lose their efficacy and thus the ability to function. When that occurs, their valuable precious metals must be recovered and refined, and new precious metal-bearing catalysts must be installed during a process “change out” to minimize production downtime. To recover the value of PGMs that remain in spent process catalysts, hydrocarbon refiners typically work through their Asset Recovery departments in cooperation with well established, highly specialized precious metals refiners.
Figure 1. Hydrocarbon processing catalysts may contain two or more PGMs, and they may also include rhenium, gold, or silver.
On another subject concerning profitability, it’s not news that over the past few years many Middle Eastern hydrocarbon producers have felt the economic squeeze caused by volatile feedstock prices, geopolitical instability, increased competition, and reduced fossil fuel consumption. While many Mideast producers have moved towards increased production of non-fossil fuel products such as fine and specialty chemicals (as well as a variety of other petrochemical end products), all of them must deal with the prospect of obtaining maximum value from the precious metals that remain in their spent catalysts.
Figure 2.Precious metal-bearing catalysts employed in
hydrocarbon and petrochemical processes are usually
dry sampled. (Figure 2)
To further cut into the profit squeeze, Gulf States refiners also face the prospect of China developing its massive shale gas resources, which could have major negative impact on Gulf region hydrocarbon producers. In fact, there have already been major mergers between Middle Eastern refining consortiums and Chinese companies that are now constructing huge hydrocracking facilities in China.
Asset Recovery Includes Catalysts’ Precious Metals
As an operator, how does all this news affect you? It’s simple, really: It is in the best interest of any hydrocarbon refining organization to look carefully at its asset recovery program with regard to acquiring highest possible value for remaining precious metals in spent process catalysts. Consider this typical example: A spent catalyst lot from a major refiner (which could weigh a half-million pounds) could easily contain $3 million in recoverable platinum. At today’s platinum price of about $1,600 tr. oz., clearly this represents a significant contribution to any organization’s profit picture.
Environmental Concerns and Legal Implications
Because environmental protection has become an important concern (with possible serious legal implications for violators), processing procedures at your refiner’s must also be thoroughly evaluated. If your refiner violates an environmental law—and there are plenty of them (go to www.sabinmetal. com/ Environmental.html, then scroll down to Environmental Codes & Standards)—not only is your refiner subject to legal action (most likely by more than one authority), but you—as the catalyst owner—may also be held responsible.
How to handle this? When selecting a refiner, you should not only be aware of how your materials will be processed, but also how spent catalysts from the refiner’s other customers are processed. It ultimately is your responsibility to determine how any solid, liquid, or gaseous byproduct is handled at the refiner’s facility. Exhaust air quality should be managed with state-of-the-art pollution control systems; and hazardous waste
In-House Moisture And Contaminant Removal
To provide an accurate determination of remaining precious metals in spent catalyst lots, representative samples of these catalysts must be obtained under accurate and repeatable conditions. Over time, process catalyst become contaminated by sulfur, carbon, volatile organics, moisture, and other unwanted elements. As a result, when the catalyst is removed from the process, it is usually moist and sticky, and it will not flow freely through automatic sampling equipment.
Contaminants in the catalysts must first be removed to assure accurate sampling and analysis of the remaining precious metals. This process is accomplished with an indirectly fired rotary kiln which not only greatly enhances sampling accuracy to help assure maximum recovery value of remaining precious metals; it can also significantly reduce overall refining costs when it is handled directly at the refiner’s facility. This is a key issue with regard to the total cost of recovery and refining and, by inference, the overall return of your precious metals. The typical rotary kiln will remove up to 25% of the materials’ sulfur content and up to 40% carbon content, usually at a rate of 300 to 1000 lbs. per hour. Most contaminants associated with spent precious metal bearing catalysts typically exhibit high loss on ignition (LOI) characteristics, in addition to the other contaminants previously mentioned. Removal of moisture is also critical to the down stream sampling process. The reason for this, is that the materials must be free flowing (with low LOI) initially to arrive at a final evaluation sample that is at least accurate to ± 2% relative. It is here that pre-burning can make a key difference; if the high moisture content and other contaminants are not removed, a suitably accurate sample cannot be obtained by the refiner, thus eliminating the possibility of providing a fair and true return value to the catalyst owner.
Sampling And Assaying Spent Catalysts
Aside from environmental issues, there are two other key functions that comprise the overall PGM-bearing catalyst recovery process. These are sampling and assaying spent catalysts. Most hydrocarbon processing catalysts are sampled by a method known as “dry sampling” (Figure 2). Dry sampling “reduces” an entire spent catalyst lot to a component with the smallest possible particulate size attainable (basically into a free-flowing homogeneous mass). This technique enables a refiner to capture multiple representative samples of an entire spent catalyst lot after its contaminants are removed.
Figure 3. Contaminants in the catalysts are removed using an indirectly fired rotary kiln, enhancing sampling accuracy and reducing overall
refining costs. (Figure 3)
In-House Sampling Reduces Costs, Saves Time
Ideally, an on-site continuous catalyst sampling system should be employed (Figure 4). A continuous catalyst system produces consistent, reproducible, statistically valid samples that represent—as accurately as possible multi-ton lots of spent catalysts. To assure highest possible recovery of PGMs, 100% of spent catalysts must be sampled in order to achieve an accurate analysis. This is an important consideration. Discrete equipment for capturing dust should also be available for subsequent sampling of the dust. Sampling systems should generate individual lot samples for the catalyst owner, the refiner, an umpire (essentially a mediator in case of disputes), and reserve samples. The refiner should also permit the catalyst owner or its representative to observe the sampling process at all times. While there are many different procedures used in the sampling process, the most important consideration is that your precious metals refiner provides total inhouse sampling capabilities. There are many reasons for this; mainly, however, it’s the control and accountability (documentation) for your specific materials while at your refiner’s facility to eliminate the possibility of mixing your spent catalyst lot with an unrelated lot.
Figure 4. To produce statistically valid samples, a continuous catalyst sampling system generates homogeneous, consistent, and reproducible intermediate samples that represent, as accurately as possible, an entire lot of spent catalysts. (Figure 4)
How To Select A Precious Metals Refiner
To ensure that a relationship with a precious metals refiner will be mutually profitable and based upon trust and fair treatment, you must address several key questions.
This checklist may help:
• Select a refiner that uses state-of the-art techniques and equipment
• Select a refiner that has a long and successful history and good reputation within the industry
• Discuss the refiner’s performance and policies that it maintains with its customers
• Ask your refiner if there will be any “hidden charges” not described in a contract proposal
• Request appropriate reference material, including environmental regulation documentation
• Determine whether the refiner has the financial resources to arrive at a settlement in a timely manner
• Select a refiner that has full inhouse capabilities – without use of outside subcontractors which might affect returns in values and timeliness
• Ask the refiner for detailed weight
• and analysis reports on shipments
• Ask the refiner if sample materials are assayed in triplicate
• Ask the refiner if it is allowable to be present during materials sampling. and whether an independent analysis can be conducted, if desired
Assaying Samples For Accuracy And Value
For accurate assaying of the remaining PGMs, the refiner should also provide its own in-house capabilities with equipment and techniques that include atomic absorption spectroscopy and inductively coupled plasma (ICP), emission spectroscopy, X-ray fluorescence, and volumetric, gravimetric, and fire assay techniques (Figure 5).
“Full Service” Logistics Helps Speed The Recovery Process
Another key issue concerns logistics/transportation of your spent catalyst lot. Your refiner should assist with complete transportation logistics directly from your facility to its facilities, no matter where your materials are located. This includes transport of hazardous materials as well, and the paperwork associated with customs export/ import arrangements.
Beware Of “Hidden Costs”
One last thought: When you work with a precious metals refiner, be aware that you may face many “hidden charges” that may not have been stated in your initial recovery/ refining quotation but will surely come back to bite you—after the fact. For example, watch for “penalty charges” based upon removal of the impurities that have accumulated in a spent catalyst lot such as carbon, sulfur, silica, moisture, or others. All of these contaminants must be removed by the refiner to assure accurate downstream sampling; in fact, without removing contaminants accurate samples cannot be obtained. Be sure to understand clearly what you’re getting into.
A Refiner Must Serve Your Best Interests
Chances are you’ve already worked with a precious metals refiner. The question is: Have you worked with the precious metals refiner that best served your interests with regard to highest possible return values, fastest possible turnaround time, and this is critical—assured your peace-of-mind with indemnification from possible environmental regulation infringements at its processing facility? Something to think about.
The bottom line is simple: With due diligence, you should be able to evaluate, select, and work with a well-established, responsible, and reliable precious metals refiner, keeping in mind that you are basically entering in a “partnership” of mutual trust and cooperation that will help provide added profits to your organization with assured peace-of-mind from start to finish.
About the author
Kevin M. Beirne is vice president sales and marketing at Sabin Metal Corp. in East Hampton, NY USA. He has been in the precious metals industry for over four decades. In addition to his sales and marketing
background, Beirne has managed analytical instrumentation, and fire assay laboratories as well as precious metals refining and manufacturing organizations . He has also been a member of the American Electroplater Society (AES), Investment Recovery Association (IRA), and is past president of the International Precious Metals Institute (IPMI). You can reach him at firstname.lastname@example.org.