Metal Testing - The Early Years

GCI TECH NOTES©

Volume 11, Number 5 A Gossman Consulting, Inc. Publication May 2006

This is part of a series of GCI Tech Notes focusing on the early development of the hazardous waste fuels programs during the early 1980s. I was hired as the facility manager for the first commercial hazardous waste operation at a cement plant in early 1980. Many of the developments in storage, processing, testing and use of hazardous waste fuels were the result of work done at a handful of plants in the early and mid 80’s. Look for issues to include topics on storage, lab testing methods, processing and the impact of HWF on cement product quality and production.

by
David Gossman, Gossman Consulting, Inc.

Many people in the industry think that metal testing of HWF and incinerator feeds came about as a result of the BIF regulations in the early 90’s. Nothing could be further from the truth. Starting in 1980 every HWF facility that I have set up, both in the US and overseas included metal testing on each batch of HWF burned with strict limits on a variety of metals that could impact product quality or stack emissions. The original list for the Paulding, Ohio facility at General Portland Cement was 12 metals including a variety of metals that are no longer tested such as copper (Cu) and selenium (Se). After the first full year of metal data on each batch of fuel used, I performed a regression analysis of the metal data against a variety of clinker parameters. That allowed us to reduce the list and shift some of the emphasis. We even added metals such as iron (Fe) and titanium (Ti) without setting limits so that we could monitor the beneficial impact that the HWF was having on the cement clinker.

Of course in 1980 there was no such thing as a commercial inductively couple plasma spectrometer (ICP) that could be used at a cement plant. Metal testing was done with atomic absorption (AA) spectroscopy. We used a Perkin-Elmer 5000 AA – perhaps the best AA ever made. It had a very large diffraction grating and great resolution along with a high level of automation. Gas controls, automatic 6-lamp turret and a programmable interface allowed us to speed up the actual instrument operation considerably. I then adapted a method that had been developed for wear metals in oil so that we could dilute the HWF samples in a mixture of MEK and xylene and aspirate the mix directly into the instrument. We could run the full suite of metals on each truck within our 30-minute time target. I still use a Perkin-Elmer 5000 AA today in my soil-testing lab. It is a terrific workhorse instrument.

In the late 80’s I ran a series of tests comparing different sample prep and instrument methods for metals in HWF. The direct dilution and aspiration technique ranked well above the use of nitric acid digestion followed by ICP in terms of recovery and did not have the level of spectral interferences that frequently produces false positives with ICP. Only two methods came out ahead. One was the use of HF-nitric-perchloric digestion followed by ICP-MS. Great data but a dangerous sample prep that takes far too much time for routine use at a HWF facility. The other excellent method was the use of energy dispersive x-ray fluorescence spectroscopy (EDXRF). The only thing that kept this method from being adopted in the US was the EPA’s insistence on continuing to require beryllium (Be) testing even though coal usually has far more Be than HWF. All of the operations that I have set up in Europe, South America and Asia use EDXRF for testing metals in HWF. With the leadership of Bruce Pederson at Systech we created an ASTM method D5839, for analysis of metals in HWF using EDXRF. If I were operating a facility today I would be using EDXRF for trucks and performing the Be determination using an AA or old ICP. Such an approach would produce better data and a faster turnaround time than the frustrating process of digesting samples.

In many cases early specifications for metals in HWF were set conservatively low until we had gathered the data necessary to predict the fate and impact of individual metals in the cement kiln system. EPA limits, established as part of the BIF regulations, were much higher in most cases than we had already set as realistic limits in the industry. In at least one case the EPA proposed a limit on Hg that was so high that I felt compelled to comment on the draft regulations suggesting that the standard be lowered. They did lower it but not to the extent that I was recommending. Of course now the agency has swung the other direction and compliance with the low Hg limit in the MACT regulations is one of the most difficult standards to both meet and demonstrate compliance with. A number of years ago we developed a dynamic computer model to predict Hg emissions from modern cement kilns because stack testing of Hg is highly unreliable. The emissions change over time and cycle up and down so that one test can show compliance and the next noncompliance with the same input rate and other operating conditions.

High levels of some metals in HWF were a frequent occurrence in the early years. Industry was still in the process of discontinuing the use of Pb and Cr based paints. In fact they were still widely used as undercoats in the auto industry at that time. I can recall testing one truck of waste paint from a toy manufacturer only to find that the Pb was over a million parts per million (remember that ppm is measured as mg/l – this stuff was heavy!) The load was rejected and as the father of a young child I quickly gathered up all her painted toys and personally tested them for Pb. On another occasion I calculated that the value of silver (Ag) in a truck that we unloaded was over $30,000. In the early 90’s at the Southdown plant in Fairborn, Ohio, a strong NIMBY movement impacted the permitting effort. The chemist at the HWF operation obtained one of the “ban the burn” signs from the group and tested the ink on the sign for Pb. He reported to the local press that the signs should all be properly disposed of as hazardous waste but that the facility would not take them because the Pb content on the sign was higher than the facility specification

Please contact David Gossman at 847-683-4188 or by e-mail at dgossman@gcisolutions.com for additional information – or if you have memories to share.