Not just scrap!
Reclamation of precious metals is big business. US Census Bureau data indicates that nearly 14,000 metric tons of precious metal scrap were exported from the U.S. in 2012 valued at $5.5 billion.
In precious metals reclamation applications, efficiency means the difference between profitability and bankruptcy. Many precious metal reclamation processes make careful use of industrial dust collection systems at multiple points along the process. In addition, many other industrial processes that make use of precious metals in their processes (e.g. platinum catalysts in refineries) often have secondary reclamation systems installed to reclaim as much of these materials as possible. In both cases, any improvement in collection efficiency can result in increased profits.
Different Ways of Using Dust Collectors to Reclaim Precious Metals
Scrap smelting is a common method for reclaiming precious metal dust. The process steps often involve cutting, chopping, or shredding of the scrap producing airborne dusts requiring capture in a dust collection system. Later, smelting furnaces require venting hoods to extract particulates as well as to control combustion gases. These gases often contain traces of the various elements in the scrap including precious metals. In other industrial applications, byproducts of a certain process may contain trace amounts of precious metals in the exhaust, nuisance dust, or pneumatically conveyed products.
Improving Dust Collection Efficiency Key to Improving Reclamation Profits
The performance of fabric filter dust collectors can vary greatly. Much depends on following industry best practice in maintenance, operations and design of these systems. When these guidelines are followed, fabric filter collectors can easily collect 99.99%+ of PM 2.5. Our blog has a number of articles on how to optimize a dust collection system, and other baghouse experts also have contributed much to this field. However, here are 4 specific areas that often come into play when system designed for precious metals reclamation:
1. Adequately size the system
Failure to properly design and size a system from the concept phase will result in low collection efficiencies. This is unfortunately common when companies undertake their own design or rely on unqualified solutions rather than dust collection engineering resources. Not only might they lack specific technical expertise and experience designing industrial dust collection systems, but sometimes the pressure to be the lowest bidder results in significantly undersizing the system. Facilities can avoid this by reaching out to experienced dust collection system manufacturers as well as doing their own research to determine a general size requirement BEFORE soliciting quotes.
2. Use highest efficiency fabric + treatment possible
Fabric filter technology has advanced greatly in the last 20 years - the greatest advances have been in the areas of high efficiency filter fabrics and PTFE membrane technology. PTFE membrane technology, for instance, can now collect more than 99.99% + of all PM 2.5 passing through it.
3. Convert to pleated filter elements if possible
Another recent advance in filter technology has been the replacing of traditional filter bags and support cages with one-piece pleated filter elements. Pleated filters pack much more total fabric into a smaller space thereby increasing the amount of filtering power without increasing the size of the unit. With more filtration surface area the system can more easily collect fines, lowering emissions. However, pleated filters cannot be used in high temp and certain chemical applications, so check with an experienced baghouse OEM before installing.
4. Optimize cleaning cycles
The majority of emissions from fabric filter dust collectors occur during the cleaning cycles. And inefficient cleaning settings prematurely wear out filters leading to higher emissions. Employing industry best practices for the cleaning system will decrease total emissions and prevent early bag failure (both overall fabric failure and wearing of holes in the fabric).
Improving dust collection efficiency for most means cutting operating costs and improving compliance with emissions regulations. For precious metal recycling facilities improving collection efficiency directly impacts the bottom line. Implementing just these four basic recommendations will lead to increased efficiency and as a result directly increase profits from any reclamation process. Using a triboelectric bag leak detector can help to minimize any product loss caused by the onset of a filter leak.
To learn more about how to improve dust collector operation, you may want to check out these resources:
How to Avoid Undersizing Your Dust Collection System - Baghouse.com
How to Avoid Undersizing Your Dust Collection System article and Full PDF Guide - Baghouse.com