Material hazards mercury

Shredded circuit boards. Circuit boards are metal boards that hold computer chips, thermostats, batteries, and other electronic components. Circuit boards can be found in computers, televisions, radios, and other electronic equipment. When this equipment is thrown away, these boards can be removed and recycled. Whole circuit boards meet the definition of scrap metal, and are therefore exempt from hazardous waste regulation when recycled. On the other hand, some recycling processes involve shredding the board. Such shredded boards do not meet the exclusion for recycled scrap metal. In order to facilitate the recycling of such materials, U.S. EPA excluded recycled shredded circuit boards from the definition of solid waste, provided that they are stored in containers sufficient to prevent release to the environment, and are free of potentially dangerous components, such as mercury switches, mercury relays, nickel-cadmium batteries, and lithium batteries. 

By a strict definition, these electrical and electronic wastes are hazardous. Fluorescent lamps contain mercury, and almost all fluorescents fail the U.S. Environmental Protection Agency (U.S. EPA) toxicity test for hazardous wastes. Fluorescent lamp ballasts manufactured in the mid-1980s contain polychorinated biphenyls (PCBs), a carcinogen most of these ballasts are still in service. Batteries can contain any of a number of hazardous materials, including cadmium (nickel-cadmium... 

These large electrical waste appliances consist mainly of iron, copper, aluminum, and insulation materials. The insulation materials are mostly inorganic. The electronic controllers contained in the appliances are classified as electronic scrap. They may contain particularly hazardous components (accumulators, batteries, condensers, mercury switches, etc.). 

The objectives sought to be achieved through disposal of refrigeration and air conditioning waste appliances are (a) separate disposal of the CFCs from the circulation system and the insulating material (b) further stripping of hazardous substances (e.g., mercury switches) and (c) recovery of ferrous metals, the priority in metal recycling. 

Heavy metals have the potential to enter the water supply from the leachate or runoff from landfills. It is estimated that nonrecycled lead-acid batteries produce about 65% of the lead in the municipal waste stream. When burned, some heavy metals such as mercury may vaporize and escape into the air, and cadmium and lead may end up in the ash, making the ash a hazardous material for disposal. 

For this purpose, the WEEE Directive has been complemented with an additional directive that limits the use of certain pollutants in these products. The EC Directive 2002/95/EC on the Restriction of the use of certain Hazardous Substances in electrical and electronic equipment (RoHS Directive) ([7], recast 2011 [9]) restricts the use of the six harmful substances/substance families lead, mercury, hexavalent chromium, polybrominated biphenyls (PBB), and polybrominated diphenyl ethers (PBDE) to 0.1% and cadmium to 0.01% w/w per homogenous material in equipment and components, but with several exemptions for a wide range of applications (Annex III and IV). 

Picric acid, in common with several other polynitrophenols, is an explosive material in its own right and is usually stored as a water-wet paste. Several dust explosions of dry material have been reported [1]. It forms salts with many metals, some of which (lead, mercury, copper or zinc) are rather sensitive to heat, friction or impact. The salts with ammonia and amines, and the molecular complexes with aromatic hydrocarbons, etc. are, in general, not so sensitive [2], Contact of picric acid with concrete floors may form the friction-sensitive calcium salt [3], Contact of molten picric acid with metallic zinc or lead forms the metal picrates which can detonate the acid. Picrates of lead, iron, zinc, nickel, copper, etc. should be considered dangerously sensitive. Dry picric acid has little effect on these metals at ambient temperature. Picric acid of sufficient purity is of the same order of stability as TNT, and is not considered unduly hazardous in regard to sensitivity [4], Details of handling and disposal procedures have been collected and summarised [5],... 

This list of substances has to be reviewed and extended by the parliament and the council as soon as further scientific evidence on other hazardous substances is available which recommends their substitution with safer alternatives. Materials or components of electrical and electronic substances can only be exempt from the substitution provision if their replacement is not scientifically ortechnically practicable or if there are no safer alternatives. Annex 1 of the directive specifies in detail which applications of lead, mercury, cadmium and hexavalent chromium fall under the above-mentioned exemption. However, these exemptions also need to be reviewed every fouryears (Preamble 11 and Article 5 (b) and (c))... 

Curtius added lead acetate to a solution of sodium or ammonium azide resulting in the formation of lead azide. In 1893, the Prussian Government carried out an investigation into using lead azide as an explosive in detonators, when a fatal accident occurred and stopped all experimental work in this area. No further work was carried out on lead azide until 1907 when Wohler suggested that lead azide could replace mercury fulminate as a detonator. The manufacture of lead azide for military and commercial primary explosives did not commence until 1920 because of the hazardous nature of the pure crystalline material. 

Polarography has been largely replaced by voltammetry with electrode materials that do not present the toxicity hazard of mercury. Principles described for the mercury electrode apply to other electrodes. Mercury is still the electrode of choice for stripping analysis, which is the most sensitive voltammetric technique. For cleaning up mercury spills, see note 18. 

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