Reclaim precious metals from spent catalysts with zero discharge
Reclaim precious metals from A case history/exposition provides valuable HPI information on catalyst recovery
R. DeSantis, Sabin Metal Corp., East Hampton, New York
Catalysts that contain platinum group metals (PGMs) are widely used in hydrocarbon processing, both for facilitating production processes, as well as for controlling/abating harmful or unlawful exhaust emissions for end-of-pipe applications. Typical catalysts employed in petrochemical/hydrocarbon processing applications incorporate PGMs, which are deposited on catalyst supports such as soluble or insoluble alumina, silica/alumina or zeolites.
At the exhaust end of a process, catalysts are also widely used for end-of-pipe control to reduce and/or eliminate atmospheric emissions of volatile organic compounds (VOCs) and other pollutants generated by hydrocarbon processes. Catalysts used for these applications typically contain platinum, palladium and to a lesser extent gold and/or rhodium, either alone or in some combination.
Virtually all chemical/petrochemical/and other hydrocarbon processing manufacturers use fixed-bed reaction catalysts. Most – if not all – of these organizations depend upon precious metals refiners to reclaim valuable metals from their spent catalysts. Precious metals may also be recovered from waste byproducts such as filter cakes, papers, cloths, polishing filters, floor sweepings and protective clothing. However, many catalyst users may not be aware of the legal implications involved concerning effluent or atmospheric discharges at the refiners they select. Choosing the wrong refiner can be a costly mistake.
The precious metals refining industry does not enjoy an especially sterling reputation with regard to environmental responsibility. When selecting a refiner, be aware not only of how your materials will be processed, but those of the refiner’s other customers as well. Determine how any solid, liquid or gaseous byproduct is handled at the facility. Ideally, refiners should operate a zero-discharge processing facility, with no effluent emitted before, during or after refining, and exhaust air quality managed with state-of-the-art pollution control systems and process water evaporation procedures to eliminate all causes of pollution.
Obtaining documentation also may help you determine whether the refiner you select violates any applicable environmental law or regulation. The Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), also known as the Superfund Act, addresses the joint customer/refiner responsibility. This law mandates that both the company which is the source of the material for precious metal recovery and the precious metal refiner share in the "cradle-to-grave" responsibility as well as the future liability, for the proper treatment of the material. Essentially, the environment must be protected to avoid serious financial and legal consequences: your refiner’s violation of these laws or regulations could result in heavy fines and legal costs to you.
As an example of what can go wrong, consider this recent case: While not directly related to reclaiming precious metals, consider the comments (in January 2000) from an Environmental Protection Agency administrator with regard to environmental contamination: "You pollute, you pay," commented the administrator at a major news conference. The news conference focused on a record, $35-million fine and associated penalty against a major oil company located in Wichita, Kansas. The case concerned two lawsuits, involving more than 300 oil spills from the company’s pipelines and oil facilities in six states; the oil was discharged into 16 lakes and streams. Based on the outcome of this case—which was settled by the company and EPA—it is obvious that the government means business with regard to pollution control and environmental damage.
An excellent way to determine if a facility meets these criteria is to look for the effective utilization of sophisticated technology such as afterburners, baghouses, wet scrubbers and liquid effluent neutralizing equipment. Also, evaluate the refiner’s approval status with local, state and federal agencies. A precious metal refiner should be willing to furnish copies of all required documentation. These include permits under the Clean Air and Clean Water acts and proof of whether the company qualifies as a bonafide precious metal refiner, as specified in the preamble to the Boiler and Industrial Furnace (BIF) rule and its amendments. Ideally your goal is to select a "zero-discharge" refiner – one that does not produce any effluent or hazardous waste byproducts.
To ensure that your relationship with a precious metals refiner will be mutually profitable and based upon trust and fair treatment, you must address several key questions. Does it use state-of-the-art techniques and equipment for measuring the precious metals content of materials to be reclaimed? Does it enjoy a long track record and a good reputation within the industry? Who are the refiner’s other customers, and can you obtain references? Does it have the financial resources to pay you in a timely manner?
You also should carefully evaluate all processing methods that the refiner uses for reclaiming precious metals. To ensure maximum yield, look for a refiner that maintains a modern, well-equipped analytical laboratory. The ideal facility would be one that uses classic volumetric, gravimetric, fire assay techniques, advanced x-ray fluorescence equipment, atomic absorption and inductively coupled plasma (ICP) emission spectroscopy. These techniques have been approved by the New York Mercantile Exchange/Commodities Exchange (NYMEX/COMEX). When used together, they provide the most exacting methods for determining precious metal content in spent materials, thus assuring the highest possible returns.
Choose a refiner that has significant in-house capability and does not rely on subcontractors. The more it costs your refiner to process your materials, the less your overall return will be. Depending upon the specific precious metal-bearing, recyclable material to be reclaimed, refiners generally use a combination of pyro-metallurgical and hydrometallurgical processes to achieve the highest possible metal recovery at the lowest possible cost.
Most refiners use a wide variety of equipment and procedures to process spent catalysts. These include rotary and crucible furnaces, kilns, roasters, thermal processors, pulverizers, granulators, screens, blenders, autosamplers, reactors, dissolvers, precipitators, electrolytic cells and filter presses. In many cases, how this equipment is employed may have a bearing on the percentage of precious metals recovered from spent catalysts and also on the refiner’s discharge policies. Do not hesitate to ask questions.
To cultivate trust, the refiner you select should be willing to provide you with detailed weight and analysis reports on your shipments. The most advanced laboratories typically assay sample materials in triplicate to assure precise precious metal measurement. A reputable organization will allow you to be present during the sampling of your materials and will permit you to conduct your own independent analysis, if so desired.
Doing your own due diligence before you select a refiner will reduce the likelihood of problems down the road. Remember, whether you like it or not, you are a "partner" of your precious metals refiner—at least that’s how the EPA may see it.
Another major concern for companies using PGM catalysts is the speed at which their spent catalyst is processed and the precious metals recovered—reclamation turnaround time. Typically, it could take as long as three months to have a new catalyst fabricated and three months to have the spent catalyst reclaimed—a period of six months during which metals may have to be financed. In the case of platinum, lease rates typically range between 5% and 10%, and recently have been as high as 50%. Palladium lease rates normally run between 8% and 15%, and have skyrocketed to 200% in the past. The fluctuation in these rates is related to worldwide production for primary (mine production) sources and the immediate, local availability of physical metal. For the catalyst user, PGM lease rates may represent a significant cost, since metals are often financed during the entire catalyst fabrication and reclamation period. By providing faster spent catalyst-reclamation turnaround times, a substantial cost savings may be realized by the catalyst user, in many cases translating into hundreds of thousands of dollars each year.
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