Mercury reclamation

Tokuyama Bay, Japan, received 6.6 metric tons of mercury wastes between 1952 and 1975 in wastewater from two chloralkali plants, although sediment analysis suggests that as much as 380 tons of mercury were released (Nakanishi et al. 1989). Unlike Minamata Bay, however, there were no human sicknesses reported, and the hair of residents contained 0 to 5 mg Hg/kg FW vs. 15 to 100 mg Hg/kg FW in Minamata residents. In 1970, a maximum concentration of 3.3 mg total Hg/kg FW was reported in tissues of Squilla, a crustacean. In 1973, a health safety limit was set of 0.4 mg total Hg/kg FW in edible fish and shellfish tissues with a maximum of 0.3 mg methyl-mercury/kg FW permitted at least five species of fish had more than 0.4 mg total Hg/kg FW, and fishing was prohibited. Contaminated sediments (>15 mg total Hg/kg) were removed by dredging and reclamation between 1974 and 1977. By 1979, the mercury content of all fish, except one species, was less than 0.4 mg total Hg/kg FW fishing was prohibited. By 1983, all fish and shellfish contained less than 0.4 mg Hg/kg FW and fishing was allowed (Nakanishi et al. 1989). 

The MRU technology is not applicable to heavy-metal-contaminated soils nor to radioactive waste contamination. The one exception to heavy-metals remediation is mercury. The vaporization temperature for mercury is well within the operating range of the MRU, and because of closed chamber construction, it is ideally suited for the removal and reclamation of mercury from contaminated soil. 

Metallic mercury is mostly a problem in confined spaces or where it is handled in industrial processes or in laboratories. It is not generally an environmental problem, more likely an industrial hazard. However, metallic mercury does occur naturally (it was mined in Spain and Slovenia, for example) and the use of mercury for metal reclamation is a potential environmental hazard in countries such as Brazil where miners use it to extract gold from river sediments. Inorganic and organic mercury may be produced from the metallic mercury during its use and subsequent release into the environment. 

SPILL CLEAN-UP ventilate area of spill if in solid form, collect in a dust pan and pour into plastic bag or sealed containers sprinkle powdered sulfur on spill in order to determine whether mercury is still present (note if it runs from yellow to brown, more clean-up is needed) sprinkle powdered zinc to suppress vaporization of small amounts of remaining mercury if in liquid form, absorb small quantities on paper towels and evaporate in a fume hood large quantities can be collected for reclamation or disposal in sealed containers. 

The retirement of mercury-cell plants has created a new issue, the disposal of their mercury inventory. This has been considered a waste by some. However, mercury remains a useful commodity and automatically regarding it as a hazardous waste may be counterproductive [96]. Handling of mercury is an issue that requires an accepted societal policy. The metal is available from strategic reserves, retired or converted cell rooms, and reclamation processes. Total stocks worldwide are estimated roughly to be 25-50,000 tons [97]. The gradual run-down of mercury inventory before retiring a plant is not a useful technique. The opposite approach, increasing the amount of mercury in the cells, has in fact been used in older plants to improve cell performance and reduce the loss of mercury to the environment [98]. 

In the United States, in 1992 the state of New Jersey prohibited sales of mercury batteries. In 1996 the United States Congress passed the Mercury-Containing and Rechargeable Battery Management Act (the Battery Act), 104—142, May 13,1996, that prohibited further sale of mercury-containing batteries unless manufacturers provided a reclamation facility, with an exemption for alkaline zinc-air button cells. 

Some secondary batteries such as Ag-Zn batteries are not disposed of but are claimed at the end of their useful life. The battery manufacturers offer a service for reclamation and precious metal can be recovered. A trace amount of mercury is embedded with the zinc oxide if the AG-Zn cell is used to suppress outgassing during normal battery operation. There are disposal requirements for certain secondary batteries deployed in aerospace and military programs, and readers or battery designers must be aware of such requirements. 

Red mud, HF, CO2 Tar pitch volatiles spent pot linings cyanide earth movements reclamation dusts. Waste water solid wastes heavy metals CO2 earth moving reclamation dusts. Waste waters heavy metals CO2 rivers and earth moving reclamation particulate matter. Waste water solid wastes cyanide mercury particulate matter, rivers earth moving reclamation. 

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