Disposing of Metal Powder
There are several guidelines, standards, and regulations regarding the disposal of metal powder in San Mateo, California. The California State Government has a Code detailing the requirements and responsibilities of those that generate metal powders. The Department of Toxic Substance Control is responsible for the evaluation and enforcement of the health-related aspects of this Code. A recent report of the DTSC has made recommendations for metal shredders producing metal powders. Apple was one of the companies that were found to be violating the Code during the DTSC evaluation. Other organizations that assist in regulating this area include the National Fire Protection Association and the Metal Powder Industries Federation. Several procedures should be followed when handling metal powders to minimize risk, which includes the risk of combustion and explosion. Respiratory distress and metal toxicity are common health hazards resulting from the improper handling of metal powders.
Disposal of Metal Powders in California
- In a powder form, metals are a higher risk than items that contain scrap tantalum anodes, wires, pins, and pellets. Metal Powder can be flammable, self-reactive, and susceptible to release when handled. Given this, there are rules in the safe disposal of metal dust.
- Fine metal powder, as defined by Calfornia Code of Regulations is a metal in a dry powder form, having a particle size of less than 100 micrometers in diameter." These powders are not considered scrap metal. They are potentially hazardous waste under these regulations.
- Metal Powders must never be disposed of in the trash.
Apple's Violation of Standards
- Corporate giant, Apple was found to have violated the disposal of metal powder standards at its electronic scrap metal shredding facility in 2011 and 2012. Apple shipped the dust from its operation to Sims Recycling Solutions, a company that was not authorized or prepared to dispose of hazardous waste.
- The Chief of the Department of Toxic Substances Control (DTSC), Keith Kaihara, when talking about the case, said, "Compliance with the hazardous waste law is fundamental in protecting the health of workers and communities as well as the environment. We are encouraged by the settlement and that Apple is working with us to take the necessary steps to comply with California's hazardous waste law."
- Apple was required to take appropriate steps to ensure metal powder produced by their operation was adequately disposed of, as well as being subjected to monitoring by the DTSC.
Misinformation About Metal Powders
- There is a considerable amount of misinformation about the disposal of metal powders. The most common misconceptions regarding metal powders are producers of metal powders must ensure they are placed in a landfill, the hazardous nature of all metal powders, and that there is no value in recycling small quantities of metal powders.
- People expect metal powders to be to flammable and dangerous to recycle when this is not always the case. They can often be recycled without their products degrading, which means they can be recycled repeatedly, unlike some other recyclable materials. Further, by recycling, energy and resources can be saved, and pollution minimized.
- Greenhouse emissions are reduced when recycling metal powders because it takes less energy to manufacture products from recyclables compared to virgin materials. It also negates the need for landfills, which minimizes the risk of water and air pollution.
Industries Using Metal Powders in Production
- A three-step process should be used to recover and recycle metal powders in industries that use the powders as part of their production process, such as the metal additives industry. This process involves retrieving any unused material from the printer, screening it, and either returning it to the printer for future use or placing it in appropriate storage.
Insights into the Proper Handling of Metal Powders
- Many scrap dealers are not adequately trained to deal with metal powders, including the safety issues around their handling. In most instances metal powders are a hazardous waste and cannot be disposed of to a scrap dealer.
- Metal powders are produced and used in the metal additives (or 3D printing) industry. The industry uses metals in a powder form, which are layered, melted, and bound together using the heat from a laser. Some metal powders are between 15 and 45 microns in diameter and represent a health hazard when inhaled or absorbed through the skin. The mishandling of metal powders can result in heavy metal poisoning or respiratory difficulties.
- Appropriate safety clothing must be worn at all times, and safety standards and procedures must be followed. An over-cautious approach represents the best practice.
- Pneumatic Vaccum Technology is used to safely transport metal powders. The bulk densities of the products range from 93 to 341 pounds. The containment is high level minimizing any worker safety or environmental issues.
- Metal powders must be handled and disposed of appropriately as they are subject to degradation and corrosion. This process is known as entropy. As entropy progresses, the product represents a higher risk of combustion through a flash-fire or explosion. Although self-combustion is unlikely, it is nonetheless essential that metal powders are handled according to the prescribed standards.
- Organizations that play a role in the development of standards relating to metal powders are the American Society for Testing and Materials, the Metal Powder Industries Federation, the International Standards Authority, the National Fire Protection Association, the Department of Toxic Substances Control and the State Government.
National Fire Protection Association Standards
- The National Fire Protection Association's NFR 484-2019 details the guidelines for the production, processing, finishing, handling, recycling, storage, and use of metal powders that are capable of combustion or explosion. The guideline aims to minimize the chance of fire or explosion when handling these powders. An operation that machines, saws, grinds, buffers, or polishes metal products, is considered capable of producing metal powders.
- NFPA 484-2019 was released in January 2019 and covers a range of different concepts relating to metal powders, including the means of determining combustibility, control of the ignition process, and hazard analysis. It also contains information that is specific to additive manufacturing, alkali metals, nano metal powders, and legacy metals. The powder and dust collection and centralized dust section has been rewritten from the 2015 version.
- Any fire that results from the combustion or explosion of metal powder is considered a Class D fire. A Class D fire extinguisher must be readily available when metal powders are handled.
California Code of Regulations
- The California Code of Regulations Title 8 Section 5174 mandates the standards for metal powders and dust that are likely to be combustible. Actions that could result in more than 25% of the lower explosive level of the metal powder being released in the air are prohibited.
- Machines, conductive surfaces, and housings in areas where there is metal powder must be ground appropriately to avoid an explosion caused by electrostatic charges. Magnetic or pneumatic sensors are required to remove metal powders that are produced through grinding, pulverizing, or shredding machinery.
- Smoking is prohibited in areas containing metal powders or dust due to the risk of explosion.
- Title 22 of the California Code of Regulations sets out the requirements around the disposal of hazardous waste. All generators of hazardous waste are required to have an identification number. A manifest is necessary when transporting, disposing of, storing, or treating hazardous waste. Hazardous waste must be labeled, marked, packaged, and placarded appropriately before transportation, as set out in Chapter 12, Section 66262. Records and reporting are mandated.
- Title 6 Section 6151 requires portable fire extinguishers to be available when metal powders are present. This section of the code dictates the placement, maintenance, and testing of fire extinguishers. It also requires the implementation of an appropriate evacuation plan.
DTSC Evaluation 2018
- The DTSC evaluates and enforces the Health Codes relating to metal shredding facilities. An evaluation of the industry was conducted in 2018. The evaluation uncovered numerous accidents and incidents of improper storing, and release of hazardous substances impacting communities.
- They found that the most appropriate level of regulation to govern the industry is a hazardous waste permit. One of the issues uncovered was the continued disposal of waste of this nature, including metal powders, in landfill facilities.
- Approximately 2,000 facilities were evaluated. 400 facilities were identified as shipping contaminated soils or waste off-site for disposal and 110 facilities were identified as having visible waste piles. Two of these facilities were found to have contaminated the soil and required to fit a concrete cap, 4 facilities have had 6 fires in the last 10 years, and several of the facilities had released toxic substances into the air.
- The main sources of hazardous waste that are treatable are lead, copper, and zinc.
- Metal residue contains metal powder. The DTSC report found that chemical stabilization treatment should be used on metal residue. The treatment requires the application of silicate solution and alkaline cement to stabilize soluble zinc, cadmium, copper, and lead.
- A range of standards were recommended in the report including a recommendation that operators be trained in waste management control and pollution control.
Metal Powder Industries Federation
- The Metal Powder Industries Federation also has standards relating to metal powder use. The standards relate to material specifications for components, methods of testing powders and components, and powder metallurgy press safety standards.
We identified several standards, guidelines, and codes that are applicable in San Mateo for the disposal of metal powders by reviewing the resources of the National Fire Protection Authority, Metal Powder Industries Federation, DTSC, and California State Government. We also evaluated a range of industry publications to find relevant insights regarding the disposal and handling of metal powders. By doing this we were able to identify definitions, greenhouse effects, common misinformation, and information relating to recycling metal powders. No standards were found that were specific to San Mateo, California, but the state and national standards are all applicable.