Removal mercury

The need to remove mercury from natural gas has been known for many years. UOP is active as the only supplier to date to offer truly regenerable mercury adsorbents. The removal of Fig by UOP s HgSIV is actually a weak reversible chemi-sorption process. 

As previously mentioned, all impurities besides mercury are removed by a first washing and cooling step in the acid plant. The mercury goes throu this wash step and requires a separate removal stage. Three different scrubbing processes are available for the removal of metallic mercury from the SO gas. Processes for removal from the acid are also used, but not frequently in the electrolytic zinc process. All processes produce a sludge that is either stored or used for the production of metalHc mercury. 

Boliden-Norzink process . This removal step is performed after the washing and cooling step in the acid plant hence the gas is dust and SO, free and the temperature is about 30 C. The gas is scrubbed in a packed bed tower with a solution containing mercuric chloride HgCl. This reacts with the vapor of metalHc mercury in the gas and precipitates it as calomel, Hg Cl  

The calomel is removed from the circulating scrubbing solution and partly regenerated by chlorine gas to HgCl, which is then recycled to the washing stage. The mercury product bleed is either used for mercury production or stored. 

Bolchem process. The concentrated 99 wt.% sulfuric acid comes from the absorption part of the acid plant and it oxidizes the mercury at an ambient temperature. The resulting mercury-containing acid is diluted to 80%, and the mercury is precipitated as insoluble cinnabar (HgS) with sodium thiosulfate. After filtering off the mercury sulfide the cleaned acid is returned to the absorption column. No acid is consumed in the process the mercury sulfide is only in an internal circulation loop. 

Outokumpu process. The mercury is removed before the washing step in the acid plant. The gas, at about 350°C, is led through a packed bed tower, where it is washed countercur-rently with 90 wt.% H SO at about 190°C. The acid is formed in situ from the absorption of 

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Atwood DA, Zaman MK (2006) Mercury Removal from Water 120 163-182 Autschbach J (2004) The Calculation of NMR Parameters in Transition Metal Complexes 112 1-48... 

According to the U.S. Department of Energy s Pacific Northwest National Laboratory (PNNL), a new nanotechnology has been developed by PNNL for mercury removal without producing harmful by-products or secondary waste. The technology is an advanced adsorption technology... 

Gil S, Lavilla I, Bendicho C (2008) Mercury removal from contaminated water by ultrasound-promoted reduction/vaporization in a microscale reactor. Ultrason Sonochem... 

Dong, J., Xu, Z.H. and Kuznicki, S.M. (2009) Mercury removal from flue gases by novel regenerable magnetic nanocomposite sorbents. Environmental Science and Technology, 43 (9), 3266-3271. 

Coupling reactions in which a metal such as mercury removes a halogen are rather common. What would be produced by a reaction of this type when mercury reacts with PF2I ... 

Carbon dioxide Sulfur dioxide Aliphatic hydrocarbons Aromatic hydrocarbons Cholinesterase inhibitors Paraquat Lead Arsenic Mercury Removal from exposure and administer oxygen Removal from exposure Removal from exposure Removal from exposure Atropine, pralidoxime Gastric lavage and dialysis Dimercaprol, penicillamine Dimercaprol, penicillamine Dimercaprol (elemental), penicillamine, dimercaprol (inorganic salts)... 

More research is needed on mercury removal technology. In the Florida Everglades, for example, using prototype wetlands of 1545 ha, removal of agricultural nutrients from stormwater reduced total mercury and methylmercury concentrations in water by as much as 70% in the first 2 years of operation moreover, total mercury concentrations in largemouth bass were about 0.1 mg Hg/kg FW muscle throughout the project site vs. 0.5 mg Hg/kg FW in adjacent areas (Miles and Fink 1998). 

MEDISORBON An adsorptive process for removing mercury and dioxins from flue-gas. The adsorbent is a dealuminated zeolite Y manufactured by Degussa. For mercury removal, the zeolite is impregnated with sulfur. Developed in 1994 by Lurgi Energie und Umwelt and piloted in Germany and The Netherlands. 

Mercury releases, anthropogenic, 16 47-49 Mercury removal, 1 650 Mercury sulfide (cinnabarite), color and bad gap, 7 335t... 

A wide range of operating conditions and design philosophies affect mercury cell efficiency. For example, the fundamental distinction between a resaturation and a waste brine process influences the temperature and brine strength profile along the length of the cell and hence the overall efficiency. Another important factor is the quality of the brine. Impurities in the brine can cause base-plate deposits, which tend to reduce the anode/cathode gap. This gradual reduction in gap requires either manual or automatic adjustment and, eventually, the cell must be taken off-line and the thick mercury removed. 

In addition, mercury is often present in natural gas and petroleum products, both of which can be the basis of feedstock for industrial reactions. These are generally carried out with aluminium rotors or condensers, and low levels of mercury attack aluminium components, causing stress fractures. Mercury-induced corrosion on aluminium heat exchangers has resulted in at least four long-term industrial complex shutdowns in Algeria, the USA, Indonesia and Thailand. These shutdowns required costly replacements and from several weeks to several months of lost production the plants have now been equipped with mercury removal units. 

Mercury captation should he carried out as far upstream as possible in order to avoid contamination of process internals regeneration of organomercury compounds after steam cracking and the need to have a mercury removal unit on all of the process effluent streams. 

The example above shows the severity of the problem that arises from the presence of mercury in natural gas. Not only is it necessary to determine the levels of mercury present, but also to remove the majority of the mercury prior to any contact with aluminium reactors. The latter of course, further compounds the problem, because if 90% or more of the mercury has been removed, then to determine the remaining mercury is even more difficult. An effective analysis system will he able to measure mercury in its organic and inorganic forms and to do so very quickly. If a mercury removal bed is losing its efficiency then it is imperative to stop the process as soon as possible. In addition, these systems are expensive to operate and it is uneconomic to switch to a new unit if the original still has some life left in it. 

Figure 3.IS shows a schematic overview of a natural gas plant and indicates samphng points that may require analysis. These are indicated prior to, between and after the mercury removal beds.

T0609 PhytoWorks, Inc., Mercury Removal Using Genetically Engineered Plants T0625 Process Technologies, Inc., Photolytic Destruction Technology... 

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