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10/1/1996 | 12 MINUTE READ

Clean Air Act Compliance for Chromium Emissions from Electrolytic Processes

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Hard chromium, decorative chromium and chromium anodizing tanks are regulated. Rinse, etch, chromate conversion tanks, lab and R&D facilities are exempt from regulations...


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The U.S. EPA and the University of Tennessee provided funding for a teleconference on the issue of chromium emissions and federal regulations. The American Electroplaters and Surface Finishers Society (AESF), National Association of Metal Finishers (NAMF) and Metal Finishing Suppliers' Association (MFSA), along with the Tennessee Department of Environment and Conservation's Small Business Assistance Program developed the conference that was telecast across the country.

The conference covered the Clean Air Act Sections one through seven, Title V permits and HAPs. Panelists in Part I include Frank Altmayer of Scientific Control Labs, Don Moroni, an environmental specialist with the Tennessee Small Business Association and Dr. Ken Newby of Atotech.

Moderator: What can be done to meet the regulations?

Dr. Newby: The rule says any method that meets the emissions standard is permissible. It spells out specifically add-on devices: Packed-bed scrubbers, fume suppressants or foam blankets. Decorative platers also have the option of trivalent chromium baths, which are controlled only by reporting their existence.

Moderator: Is a Title V Permit required for chromium emissions?

Mr. Altmayer: Regulations, as they exist today, do require a Title V permit for all emission sources, even trivalent chromium sources. The industry, through its Director of Government Relations, Bill Sonntag, has negotiated with EPA to have a five-year deferral put into the Federal Register. If the five-year deferral is granted, the emission sources do not have to apply for five years. (EPA has granted the five-year deferral on Title V permits -- Editor)

Moderator: What emission standard must be met under the new rule for decorative chromium and chromium anodize tanks?

Mr. Altmayer: There are two options. First, finishers can use a fume suppressant and reduce the surface tension of the processing solution below 45 dynes/cm. If successful, they no longer need to do any emission testing and have no emission standards to comply with.

If they do not use fume suppressants, and choose to use an emission control device, the standard is 0.01mg/dscm of air for decorative chromium platers and chromium anodizers.

Moderator: What about hard chromium plating?

Mr. Altmayer: Hard chromium plating falls into three categories. There are new sources. Existing sources are those that were in existence prior to December 16, 1993, and these are divided into small and large. The new sources, no matter their size, and the large existing sources must meet a standard of 0.015 mg of total hexavalent chromium per dscm. Small sources must meet 0.03 mg/dscm.

Moderator: What about trivalent chromium emission standards?

Dr. Newby: Trivalent chromium decorative platers merely need to tell the state that they are using this chemical, and they must use a fume suppressant or wetting agent. All commercial baths meet this requirement. Users must keep track of chemical purchases.

Moderator: How does a decorative plater using this technology demonstrate compliance?

Dr. Newby: For finishers using fume suppressants, they will have to measure surface tension. The most common methods are a stalagmometer and tensiometer. Using either, a finisher has to demonstrate that the surface tension of the tank is 45 dynes/cm or lower. The finisher needs to do this initially every four hrs. If he shows compliance over a period of time, this can be extended to every 40 hrs of tank use.

Moderator: Are there advantages to using EPA-prescribed methods?

Mr. Moroni: The regulations do not specify that these methods be used; however, if a finisher chose to use an alternative method, proof of compliance is the finisher's responsibility.

Moderator: In the regulations, what qualifies a hard chromium facility as either small or large?

Mr. Altmayer: To determine whether a facility is large or small add up all the rectifier capacity for hard chromium plating and multiply the sum total by 8,400 operating hrs per year. This total is then multiplied by 0.7 (utilization factor) to determine amp/hr/year capacity. If the value is greater than or equal to 60 million amp/hr/year, it is a large facility.

Moderator: What kind of add-on technology does EPA regulate under the new regulations?

Mr. Altmayer: EPA says finishers can use any control device. But it recognizes a packed bed scrubber for meeting the 0.3 mg/cu meter standard. For the 0.015 mg/cu meter standard, EPA recognizes advanced composite mesh pad systems as control devices. It also recognizes that a fiber-bed mist eliminator could be used to achieve the 0.015 standard or lower.

Moderator: What about chemical fume suppressants?

Dr. Newby: EPA allows any chemical fume suppressant that lowers surface tension to 45 dynes. It also allows a foam blanket of greater than one-inch high. This is more difficult to measure and maintain. You are not told where to measure, and the foam tends to be sucked up into the scrubber system.

Moderator: When must the new standards be achieved?

Mr. Moroni: For existing hard chromium electroplaters and anodizers the date is June 25, 1997. For existing decorative chromium platers the date is January 25, 1996. Any new or reconstructed source must achieve at the time of start-up. New sources started after December 16, 1993, and before January 25, 1995, must negotiate with their local air pollution control board.

Moderator: Is a control device needed for a large non-electrified chromium etch tank with chromium in it?

Mr. Moroni: The regulations are very specific on that. This may be an etch tank used in plating on plastics, which usually has a lot more chromium in it; however, non-electrified tanks are exempt.

Moderator: What is EPA's rationale in delaying Title V permits five years?

Mr. Altmayer: We approached EPA from the standpoint that the requirements for a Title V permit assume that the discharger is a major source. A major source discharges more than 10,000 lb/yr of regulated material. These electroplating and anodizing operators emit small quantities. Under maximum conditions, it might be 10 lbs/yr. EPA decided to regulate these operations based on the hazardous nature of chromium, rather than the 10,000 lb limit. We approached them from the standpoint that since we discharge small amounts, it would be unreasonable to require a Title V permit for operations such as decorative plating with trivalent and hexavalent chromium. This is an economic burden. EPA recognized and agreed with that and has decided to issue a five-year deferral. After five years EPA has promised that Title V permitting will be easier so hard chromium platers who still have to apply for Title V will have an easier time and spend less money doing it.

Moderator: If a company is using less than 60 million amps, yet has the capacity to use more, can it still be a small electroplater?

Mr. Altmayer: The first thing the company could do is sign on to a federally enforceable limit on the rectifier capacity, but that means it would have to apply for a Title V permit, which it may not want to do. It may install amp/hr meters and use them to demonstrate that they are using less than 60 million amp/yr, although they have the capacity to exceed that.

Moderator: The company I work for has been in business since 1950 and is grandfathered on any type of air permit. If it adds to current emission systems to come into compliance with new standards, will it need an air permit?

Mr. Altmayer: If EPA files a five-year deferral, then on the basis of the federal regulation you do not have to apply for a Title V Permit. However, there are local regulations. Check with local authorities. States are always allowed to be more strict and have more regulations.

Moderator: Do fume suppressants cause pitting on bright surfaces? Does this make fume suppressant use prohibitive?

Dr. Newby: Modern fume suppressants do not cause pits. Old ones could result in particles in the bath that may have caused pitting. Pits usually result from poor base metal.

Moderator: Can meeting regulations be as easy as using a fume suppressant and fume blanket?

Dr. Newby: It is only that easy if you are a decorative plater or anodizer. Hard chromium platers have to use add-on devices. Most of the world uses fume suppressants for hard chromium plating. The U.S. EPA chose not to recognize it as one of the methods; therefore add-on devices will be necessary to meet regulations.

Mr. Altmayer:As I understand the regulations, fume suppressants that lower the surface tension are as simple as that. But if you choose to use foam blankets, which do not lower surface tension stack tests must be done to prove that it meets the 0.01 mg/cu meter standard.

Dr. Newby: One of the functional problems with foam blankets is that when you get a thick layer of foam it entraps hydrogen. So there is the possibility of a hydrogen explosion. Also, the foam can be sucked into your ventilation system. Also, until you turn the current on, the foam blanket does not exist. So you do get fugitive emissions. Fume suppressants work 100 pct of the time.

There are different fume suppressants. The old non-permanent type were non-fluorinated and inexpensive. You poured them in by the gallon. They broke down in the bath forming trivalent chromium and possibly particulates. Not too many people recommend their use, but the inexpensive price is attractive.

The permanent ones are fluorinated. Most of those on the market have a thin foam blanket when in use and control by lowering surface tension.

There are products out there that lower surface tension and have anti-foaming agents that remove foam blankets. This lowers the possibility of hydrogen explosions.

Moderator: We installed a comp mesh pad scrubber in 1994 and conducted emission testing about one month later. Is this enough to prove compliance or will testing have to be done again when the regulation goes into effect in January 1997?

Mr. Moroni: The initial performance only has to be done once, provided that you pass. It is important for anyone who does this that his control equipment be optimized. But testing is not done on a continuous basis. If you pass the first one, that is all that is required.

Dr. Newby: One of the other requirements is that you have to notify your state or regulatory authority in advance of testing. There is a time period in which you have to make this notification. Possibly, if an individual ran a test and the state did not know, he may have to do some negotiating.

Mr. Altmayer: It is also important that operating conditions under which the test is conducted remain the same. If the tank has been modified, if different current densities are used now than when the test was conducted, a new test is necessary.

Moderator: What does EPA mean by the term reconstructed?

Mr. Moroni: Reconstructed, as defined by EPA in the general provisions of the regulations, is an expenditure of 50 pct or more of original capital costs of the equipment to overhaul or add to your existing system. This is reconstruction and considered a new source.

Moderator: Often MSDS indicate possible carcinogens in fume suppressants; therefore, there is some reluctance in using them. What is the advantage of chemical fume suppressants over poly balls?

Dr. Newby: The advantage of chemical fume suppressants is that EPA recognizes them as a control means and they do not recognize poly balls. Poly balls have been a common thing, but they do not really cut down on the submicron particles that are the most difficult to control.

Mr. Altmayer: The problem with this type of control is that you lose the balls in processing. They come out with parts and fall out of the tank.

Moderator: What are some of the methods for testing emissions?

Mr. Altmayer: There are three test methods for measuring emissions: Method 306, 306A and CARB (California Air Resources Board) 25, which was used as a basis for 306A. 306A is an isokinetic sampling technique that I would not recommend any plater attempt alone. You need a very expensive piece of equipment, and it is a complicated test. EPA recognized that this type of sampling can be expensive. Therefore, EPA came up with a simplified method using a sampling device that you can build yourself. This is method 306A. I would not say it is a simple technique. It is a laborious process that takes two people. You have to drill holes in the right spots in your ductwork. One person has to go up and do a traverse, which means taking samples at different points within the duct for specific amounts of time. Air samples are put through the scrubber system, and the scrubbant is analyzed by inductively coupled plasma spectrometry, graphite furnace or ion chromatography. The chromium is then quantified. You need two people for sampling and a well-equipped lab for the analysis. Typical tests for 306A may cost three to five thousand dollars. The isokinetic testing would be higher than that.

Moderator: What method would you use to measure surface tension, and would you describe the measuring instrument?

Dr. Newby: There are two methods. 306B uses a stalagmometer. It mounts to a piece of glassware that costs about $100. You pull solution up into the tube and count drops going out of a specified volume. The weight of each drop can be calculated from the total volume of the tube, the number of drops that fall and from the density for the sample. The problem with this is cleanliness and housekeeping. In order to get a good number, you have to do a lot of preparatory work. Also, the glassware tends to break easily, so you need one or two pieces. Measurements are made every four to 40 hrs, depending on whether or not the user is in compliance.

The other method is a tensiometer, where you have a ring that you pull out of the solution and measure the force on it. This piece of equipment usually costs about two or three thousand dollars. However, it is quick and easy to use. For a plater with a large number of tanks, this would not be an economic test method because of the labor commitment.

Moderator: Must you do anything else when testing emissions?

Moderator: (answers the question) You must establish a range of controls or operational system parameters for the monitoring systems. Since you must maintain ongoing monitoring, the regulations specify system operating parameters needing control. But because each control method is different, no single control values have been set for these parameters. Site specific values are set for your system during testing. Specific parameters to be monitored and monitoring frequency are determined by your own emission control system.


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