Mercury oxide, recovery

Mercury (ii) oxide, recovery of, in preparation of chlorine (I) oxide, 5 157, 159... 

Many mercury compounds are labile and easily decomposed by light, heat, and reducing agents. In the presence of organic compounds of weak reducing activity, such as amines (qv), aldehydes (qv), and ketones (qv), compounds of lower oxidation state and mercury metal are often formed. Only a few mercury compounds, eg, mercuric bromide/77< 5 7-/7, mercurous chloride, mercuric s A ide[1344-48-5] and mercurous iodide [15385-57-6] are volatile and capable of purification by sublimation. This innate lack of stabiUty in mercury compounds makes the recovery of mercury from various wastes that accumulate with the production of compounds of economic and commercial importance relatively easy (see Recycling). 

Natural gas contains both organic and inorganic sulfur compounds that must be removed to protect both the reforming and downstream methanol synthesis catalysts. Hydrodesulfurization across a cobalt or nickel molybdenum—zinc oxide fixed-bed sequence is the basis for an effective purification system. For high levels of sulfur, bulk removal in a Hquid absorption—stripping system followed by fixed-bed residual clean-up is more practical (see Sulfur REMOVAL AND RECOVERY). Chlorides and mercury may also be found in natural gas, particularly from offshore reservoirs. These poisons can be removed by activated alumina or carbon beds. 

As mentioned above, approximately 7% of the total sulfur present in lead ore is emitted as S02. The remainder is captured by the blast furnace slag. The blast furnace slag is composed primarily of iron and silicon oxides, as well as aluminum and calcium oxides. Other metals may also be present in smaller amounts, including antimony, arsenic, beryllium, cadmium, chromium, cobalt, copper, lead, manganese, mercury, molybdenum, silver, and zinc. This blast furnace slag is either recycled back into the process or disposed of in piles on site. About 50 to 60% of the recovery furnace output is slag and residual lead, which are both returned to the blast furnace. The remainder of this dross furnace output is sold to copper smelters for recovery of the copper and other precious metals. 

Can recovery mercury contaminants in chloride, sulfide, or oxide forms while preventing the release of sulfur or chlorine into the process exhaust. 

The raw minerals mined from natural deposits comprise mixtures of different specific minerals. An early step in mineral processing is to use crushing and grinding to free these various minerals from each other. In addition, these same processes may be used to reduce the mineral particle sizes to make them suitable for a subsequent separation process. Non-ferrous metals such as copper, lead, zinc, nickel, cobalt, molybdenum, mercury, and antimony are typically produced from mineral ores containing these metals as sulfides (and sometimes as oxides, carbonates, or sulfates) [91,619,620], The respective metal sulfides are usually separated from the raw ores by flotation. Flotation processes are also used to concentrate non-metallic minerals used in other industries, such as calcium fluoride, barium sulfate, sodium and potassium chlorides, sulfur, coal, phosphates, alumina, silicates, and clays [91,619,621], Other examples are listed in Table 10.2, including the recovery of ink in paper recycling (which is discussed in Section 12.5.2), the recovery of bitumen from oil sands (which is discussed further in Section 11.3.2), and the removal of particulates and bacteria in water and wastewater treatment (which is discussed further in Section 9.4). 

Mercury Recovery.. The methods would be costly if the mercury could not be recovered and reworked. Details of a simple procedure for recovering the mercury by converting the mercuric bromide to the oxide and heating the oxide have been published.41... 

Notes. The method removes the sulphide interference from the cold-vapour mercury signal. Concentrations of sulphide as high as 20mgr1 S2-(as Na2S) do not interfere with the recovery of inorganic mercury added to distilled water. However, the oxidation technique suffers from chloride interference. If chloride is present in the sample it utilises oxidant and is oxidised to chlorine which interferes with the cold-vapour detection by absorbing radiation at the same wavelength as mercury. 

The volatilization and leaching of various forms of mercury (elemental, mercuric sulfide, mercuric oxide, and mercurous oxide) from soils or wastes was examined using the headspace method for volatilization and the Resource and Conservation Recovery Act (RCRA) leaching protocols for leaching through soil to determine if the leachates exceeded the RCRA limit of 200 g/L (ppb) (Willett et al. 1992). With the exception of mercuric sulfide, the other forms of mercury increased in concentrations in the headspace vapor and in the leachate as the soil concentrations increased, although the elemental mercury... 

If a mercury polluted stream contacts a palladium catalyst, severe deactivation occurs. This phenomenon is partially reversible as a thermal, oxidative regeneration permits recovery of some of the catalytic activity. Moreover and in contrast to arsenic, mercury is removed from the solid during this thermal treatment. This means that the gas effluent is polluted by mercury. Another imjxirtant damaging consequence of mercury is the corrosion of aluminimi containing materials (heat exchangers). 

The almost quantitative oxidation/complexation of palladium(O) in powder or foils by Me2dazdt 2I2 in THF, acetone, acetonitrile, and methylethylketone (MEK) to afford Pd(Me2dazdt)2](l3)2 makes this synthetic route appealing for practical industrial applications. A selective process for Pd-recovery from model three-way car converters was simulated obtaining a Pd-extraction yield > 90%, and was proposed as an alternative to hydrometallurgical processes. Liquid mercury is also quantitatively dissolved with production of the neutral complex [Hg(Me2dazdt)l2] in which the metal ion resides in a severely distorted tetrahedral coordination environment. ... 

---