Paint containing Chromium VI and Lead
Chromium VI and lead are hazardous substances frequently present in specific types of paints, particularly those utilized for outdoor purposes (owing to their ability to resist corrosion) or in situations where robust durability is essential (owing to their strengthening characteristics). These paints can become hazardous when disturbed, such as during demolition, posing risks to workers and the environment, particularly when exposed to fast rotating tools or elevated temperatures (for example disc grinders or torch-cutting tools).
Sampling techniques
Various rapid test methods, such as the handheld X-ray fluorescent (HXRF) scan and chemical tests with indicators, can be used to detect the presence of Chromium VI and Lead, limiting the number of lab tests. The HXRF scanner (for a test location, see Figure 1) provides insights regarding the identification of substances, but is expensive and requires maintenance and calibration.
Chemical indicator tests are less costly. They involve scratching off paint and applying liquid solutions specific to Chromium VI or Lead. The extent of discoloration serves as an approximate measure of concentration. Subsequent to the rapid tests, lab tests can accurately determine the concentration.
Removal methods
The removal of Chromium VI and lead paint requires the creation of a hermetically sealed zone, either in situ or outside after the contaminated parts have been safely dismounted, utilizing grit blasting or chemical removal.
- Grit blasting involves removing paint with abrasive materials, such as sand or dry ice, which can pose health risks to workers and increases environmental impact.
- Chemical removal minimizes dust production, but the chemical products generate extra polluted waste materials that must be taken care of. Both methods require workers to use protective gear. They yield pure metal scrap but entail waste treatment considerations. Choosing between them involves balancing worker safety, environmental impact, waste management, and cost.
Release measurements
The release measurements for Chromium VI and Lead lack established norms or procedures for clearing spaces post-removal, unlike those for asbestos-containing materials (ACM) and refractory ceramic fibers (RCF). While methods like Phase Contrast Microscopy (PCM) are utilized for ACM and RCF, providing an index of fiber concentration, no equivalent method exists for Chromium VI and Lead. Consequently, there is a gap in standardized protocols for assessing and clearing spaces after the removal of Chromium VI and Lead materials, highlighting a need for further research and development in this area.
Waste handling: packaging, transportation, and disposal
Waste packaging for Chromium VI and Lead depends on removal methods. If the contaminated object was removed as a whole, without separating the paint containing Chromium VI or Lead, it is placed in foil-equipped containers, marked per the Agreement concerning the International Carriage of Dangerous Goods by Road (ADR rules).
If the paint containing Chromium VI or Lead is removed on site, it is packed in 120-litre plastic drums (see Figure 2), also marked accordingly. Transporting Chromium VI and Lead waste demands strict safety precautions due to the hazardous nature of these materials.
Despite the absence of specific ADR rules, using covered containers is vital to prevent exposure. Careful handling is crucial to maintaining packaging integrity and ensuring safety for both the environment and workers. Disposal options for Chromium IV and Lead polluted scrap include landfilling and treatment at specialised facilities. While landfilling is permitted under certain conditions, capacity limitations often require the treatment of scrap before disposal. Until recently Purified Metal Company (PMC) in the Netherlands offered a unique melt pool solution capable of treating all waste associated with scrap materials.
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