Monel reaction with

Nickel additions reduce corrosion due to both caustic solutions and ammonia. Monel is resistant to attack in ammonia-containing waters and vapors. Reactions with ammonia are as follows ... 

The apparatus consists of a simple vacuum manifold similar to that shown in Fig. 4. The vacuum manifold should be fabricated from nickel or Monel metal, with silver-soldered or Swagelok connections. Valves should be of Monel metal, and the traps and scrubber, the function of which is to remove hydrogen fluoride vapor from the C103 F product, may be constructed conveniently of poly(chlorotrifluoroethylene) (Kel-F) tubing. A nickel cylinder of 500-ml. or 1-1. capacity serves as a reaction vessel, and a 500-ml. Monel bulb or similar vessel may be used as a product receiver. The scrubber (about 1-in. o.d.) is charged with pellets of sodium fluoride prepared in a separate operation by heating sodium... 

The first synthesis of XeFe was also reported in 1962. All syntheses are best carried out in nickel or monel reaction vessels. From the equilibrium constants for the formation of xenon fluorides, " it is evident that an excess of fluorine is necessary to minimize the formation of Xep4. In addition, the reaction temperature should be as low as possible, yet consistent with a reasonable reaction rate. In the presence of Nip2 as catalyst the activation energy for the xenon-fluorine reaction is lowered and the reaction proceeds rapidly at 393 K, in contrast to 523 K without catalyst. 

Single crystals of gold trifluoride were grown by an improved technique. Freshly precipitated gold powder was treated with fluorine gas at 160 lb. in. and 360° in a monel reaction vessel whose top was cooled to 20°, and after 12—14 hr. bright golden-yellow needles of AuF, formed on the cooled surface. The crystals, which were elongated... 

Sulfur tetrafluoride is a hazardous and highly toxic gas [4], in some aspects comparable with phosgene [12]. For reactions with SF4 with or without HF autoclaves made from Hastelloy C with Monel 400 piping and valves are recommended [13]. When handling SF4 sufficient ventilation must be provided and protective goggles and gloves should be worn. On autoclave depressurization, excess SF4 and HF should be scrubbed with potassium hydroxide solution. 

In the U.S. Department of Energy (DOE) plant at Paducah and the Comurhex plant at Pierrelatte [B5], UF4 is converted to UF by reaction with fluorine in a tower reactor. Solid UF4 and a slight excess of fluorine gas are fed at the top of a monel tower with walls cooled to around 500°C. Most of the UF4 reacts almost instantaneously with a flame temperature of around 1600°C. Small amounts of unreacted UF4 and uranium oxides are removed from the bottom of the tower and recycled to the hydrofluorination step. 

UF4 is converted to UF by reaction with fluorine at 425 to 53S C in an air-cooled, monel fluid-bed reactor charged with CaF2 diluent to improve heat transfer. Because of nonvolatile fluorides present in the crude UF4 feed, a small amount of CaF2 is continuously removed from the bed and processed for uranium recovery by reaction with fluorine in an ash cleanup reactor. Product gases from the primary reactor are passed through a cold trap to condense most of the UFg. Unreacted fluorine in off-gas from the cold trap is removed by reaction with UF4 in a fluorine cleanup reactor. Effluent passes through a filter, additional cold traps, and a KOH scrubber. 

Fluorine attacks all organic compounds except CF4. The inorganic compounds that react with fluorine include many, such as asbestos, that are relatively stable to the other halogens. Reaction with water often leads even to explosions. Metals react with fluorine at room temperature some form an impermeable fluorine layer on the surface which protects them against further corrosion, in particular Monel metal, nickel, aluminum, magnesium, iron, and steel. Glass is not attacked by fluorine if it is free from HF and dry. 

Cerium and terbium tetrafluoride can be prepared by the action of fluorine, xenon difluoride, and chlorine trifluoride on Ce02 or CeFs, and Tb407 or TbFs, respectively. These reactions are carried out at temperatures of 300-400 C in nickel or monel containers with exclusion of moisture and oxygen, For further details see the Gmelin Handbook (1976) and the literature cited therein. The preparation of... 

Disposal of NF3 via reaction with activated charcoal (forming N2 and CF4) has to be done in a fluidized bed to assure the transfer of the heat of reaction and to prevent gas adsorption [1,2]. A disadvantage is, however, the formation of toxic and hazardous N2F4 [1 ] which also may take place when NF3 is destroyed by introducing the gas through a bed of nickel or Monel turnings maintained above 550°C [2]. 

In spite of the well-known hazards associated with its use, and its chemical activity toward glass and many other materials, hydrogen fluoride has been used as a solvent since it was first prepared in the anhydrous state by Fr my (1856). Its boiling point, 19.5°C, is not inconveniently low, but it is easily removed from a reaction mixture by distillation during workup. HF may be handled in copper, nickel, or Monel vessels, with minimal reaction, though only Pt or Pl/Au alloy does not cause any contamination. Nowadays vessels lined with Teflon or pctfe (poly(chlorotrifluoroethene)) are used. 

Disposal of nitrogen trifluoride can be accomplished by combustion with a fuel such as activated charcoal, hydrocarbons, or metals at elevated temperatures. Reactions with activated charcoal produce nitrogen and carbon tetrafluoride. Carbon bed temperatures must be maintained above 1000°F (538°C) to assure reaction and to prevent gas adsorption. Similarly, nitrogen trifluoride streams can be scrubbed by introducing the gas through a packed bed of nickel or Monel turnings maintained above 1000°F (538°C), followed by caustic scrubbing. 

Cu, and 3% Fe and is resistant to reaction with most chemicals. Monel does not react even with flnorine gas at room temperature. Nickel-steel alloys are nsed for armor plates, and elemental nickel is often plated onto other metals as a protective coating. 

Monel and nickel are the preferred materials of constmction for cylinders and deHvery systems however, copper, brass, steel, and stainless steel can be used at room temperature, providing that these metals are cleaned, dried, and passivated with a fluoride film prior to use. Studies have shown that fluorine passivation of stainless steel and subsequent formation of an iron fluoride layer prior to WF exposure prevents reaction between the WF and the stainless steel surface (23). 

The reaction mixture is filtered. The soHds containing K MnO are leached, filtered, and the filtrate composition adjusted for electrolysis. The soHds are gangue. The Cams Chemical Co. electrolyzes a solution containing 120—150 g/L KOH and 50—60 g/L K MnO. The cells are bipolar (68). The anode side is monel and the cathode mild steel. The cathode consists of small protmsions from the bipolar unit. The base of the cathode is coated with a corrosion-resistant plastic such that the ratio of active cathode area to anode area is about 1 to 140. Cells operate at 1.2—1.4 kA. Anode and cathode current densities are about 85—100 A/m and 13—15 kA/m, respectively. The small cathode areas and large anode areas are used to minimize the reduction of permanganate at the cathode (69). Potassium permanganate is continuously crystallized from cell Hquors. The caustic mother Hquors are evaporated and returned to the cell feed preparation system. 

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