Hazards secondary

Zinc fertilizers made from recycled hazardous secondary materials. U.S. EPA promulgated a conditional exclusion from the definition of solid waste for hazardous secondary materials that are recycled to make zinc fertilizers or zinc fertilizer ingredients. Zinc, an important micronutrient for plants and animals, can be removed from zinc-rich manufacturing residue and used to produce zinc micronutrient fertilizer. A second conditional exclusion applies to the zinc fertilizer products made from these secondary materials. 

A measure is preventive if it prevents the occurrence of a runaway, a decomposition, or a hazardous secondary reaction. The system conditions remain close to operating conditions. Excessive increases in temperatures and/or pressures are avoided. Preventive measures include feed rate control systems, interlocks to prevent the reaction from starting unless sufficient diluent is present or the cooling system is working, and tests for the presence of catalysts or unwanted impurities. Preventive measures are always to be preferred over protective or mitigating (defensive) measures. 

US Environmental Protection Agency (US EPA) (2002a) Zinc fertilizers made from recycled hazardous secondary materials. Federal Register, 67(142), 48393-415. 

An example of a second-order reaction which can be optimized in respect to the MSTR is shown in Figure 4-83. The value for the optimum process temperature approximately amounts to 125 C. Hazardous secondary effects, which would become perceptible only above temperatures of 170°C, would be excluded inherently safely. 

Two tables help determine the requirement for placards (49 CFR 172.504). DOT requires placards for secondary hazards. Secondary hazards must follow the requirements contained in 49 CFR 172.519. 

Depending on the nature and quantity of the shipment, placarding completes the shipment-identification process. Larger than labels, placards measure 10%" X lOM" but retain a similar square-on-point design. Placards deal with a specific hazard class of materials. DOT requires strict specifications for color, size, and wording and placement on a shipping vehicle (49 CFR 172.500.172.560). Two tables help determine the requirement for placards (49 CFR 172.504). DOT requires placards for secondary hazards. Secondary hazards must follow the requirements contained in 49 CFR 172.519. 

The Identification of Non-Hazardous Secondary Materials That Are Solid Waste rule published by the US Environmental Protection Agency (EPA) in 2012 determines whether non-hazardous secondary materials are considered fuels or wastes when burnt. Combustion units that burn non-hazardous secondary materials that are classified as fuels are regulated as boilers under Section 112 of the Clean Air Act, while units that burn materials that are classified as wastes are regulated as incinerators under Section 129 of the Clean Air Act. In the rule, the EPA identified two secondary materials (resinated wood and scrap tyres managed under the oversight of the established tyre collection programmes) as non-wastes when used as fuel, and also identified off-specification tyres managed under the contractual relationship as non-waste fuels. However, scrap tyres that are discarded in stockpiles, landfills or monofills will be considered wastes unless these tyres are processed as specified in the rule. 

Economic Considerations. The principal economic consideration is, of course, total installed system cost, including the initial cost of the flow primary, flow secondary, and related ancillary equipment as well as material and labor required for installation. Other typical considerations are operating costs and the requirements for scheduled maintenance. An economic factor of increasing importance is the cost of disposal at the end of normal flow meter service life. This may involve meter decontamination if hazardous fluids have been measured. 

The U.S. Environmental Protection Agency, under the Safe Drinking Water Act, set the secondary contaminant level for silver ia drinking water at 0.1 mg/L (20). Secondary contaminants are not considered to be hazardous to health and thus the limits are not federally enforceable. 

Occasional brief contacts of Hquid carbon tetrachloride with unbroken skin do not produce irritation, though the skin may feel dry because of removal of natural oils. Prolonged and repeated contacts may cause dermatitis, cracking of the skin, and danger of secondary infection. Carbon tetrachloride is apparenfly absorbed through the skin but at such a slow rate that there is no significant hazard of systemic poisoning in normal industrial operations. 

---