Carbon disulfide recovery

CARBON DISULFIDE. CSj- Alloy 1100 was resistant to carbon disulfide in laboratory tests conducted at ambient temperature and at the boiling point. Aluminum absorbers, distillation columns, condensers, and piping have been used in carbon disulfide recovery systems. Alloy 356.0 valves have been used for handling carbon disulfide. See also RefUDp. 129, (2)p. 146, (3)p. 51 (7) p. 51. 

Designed primarily for benzol recovery. fDesigned primarily for carbon disulfide recovery. Source Silver and Hopton, 1942... 

AEROPHINE 3418A promoter is widely used ia North and South America, AustraHa, Europe, and Asia for the recovery of copper, lead, and ziac sulfide minerals (see Elotatton). Advantages ia comparison to other collectors (15) are said to be improved selectivity and recoveries ia the treatment of complex ores, higher recoveries of associated precious metals, and a stable grade—recovery relationship which is particularly important to the efficient operation of automated circuits. Additionally, AEROPHINE 3418A is stable and, unlike xanthates (qv), does not form hazardous decomposition products such as carbon disulfide. It is also available blended with other collectors to enhance performance characteristics. 

Manufacture. An extensive technology was developed initially ia the 1930s for isolation of ammonium thiocyanate from coke-oven gases, but this technology is no longer practiced ia the United States (372). However, such thiocyanate recovery processes are used iadustrially ia Europe. Likewise, the direct sulfurization of cyanides to thiocyanates is not practiced commercially ia the United States. The principal route used ia the United States is the reaction of carbon disulfide with aqueous ammonia, which proceeds by way of ammonium dithiocarbamate [513-74-6]. Upon heatiag, the ammonium dithiocarbamate decomposes to ammonium thiocyanate and hydrogen sulfide. 

In a modem carbon disulfide plant, all operations are continuous and under automatic control. On-stream times in excess of 90% are obtainable. The process is in three steps melting and purification of sulfur production and purification of carbon disulfide and recovery of sulfur from by-product hydrogen sulfide. A typical process appears in the flow diagram of Figure 1 (50). 

Raw material usages per ton of carbon disulfide are approximately 310 m of methane, or equivalent volume of other hydrocarbon gas, and 0.86—0.92 ton of sulfur (87,88), which includes typical Claus sulfur recovery efficiency. Fuel usage, as natural gas, is about 180 m /ton carbon disulfide excluding the fuel gas assist for the incinerator or flare. The process is a net generator of steam the amount depends on process design considerations. 

For the spectrophotometric method, the evolved carbon disulfide is reacted with copper acetate and diethylamine to form a yellow copper complex which can be measured at 435 nm." The recoveries range between 70 and 90%. Reproducibility of this method was improved by reducing the time and the mode of sample pretreatment. Since all alkylenebis(dithiocarbamates) decompose to carbon disulfide by acid degradation, the above analytical methods are not selective. The result is the measured total residues of all alkylenebis(dithiocarbamates) related products. However, this method is recommended as standard method S15 for alkylenebis(dithiocarbamates) by the German Research Association. ... 

The extraction time has been observed to vary linearly with polymer density and decreases with smaller particle size [78,79]. The extraction time varies considerably for different solvents and additives. Small particle sizes are often essential to complete the extraction in reasonable times, and the solvents must be carefully selected to swell the polymer to dissolve the additives quantitatively. By powdering PP to 50 mesh size, 98 % extraction of BHT can be achieved by shaking at room temperature for 30 min with carbon disulfide. With isooctane the same recovery requires 125 min Santonox is extractable quantitatively with iso-octane only after 2000mm. The choice of solvent significantly influences the duration of the extraction. For example talc filled PP can be extracted in 72 h with chloroform, but needs only 24 h with THF [80]. pH plays a role in extracting weakly acidic and basic organic solutes, but is rarely addressed explicitly as a parameter. 

Mixtures with nitrobenzene were formerly used as liquid high explosives, with addition of carbon disulfide to lower the freezing point, but high sensitivity to mechanical stimulus was disadvantageous [1], Dining the recovery of acids from nitration of toluene, mixtures of the oxide with nitrotoluene or dinitrotoluene may... 

Mixed Solvents. In general, polar compounds usually show low recoveries from charcoal. By adding several percent of a polar solvent to the carbon disulfide desorbent solvent, recovery is often improved by 10 to 20% (16,17,18). Methanol is the most frequently added polar solvent, and it is usually effective as long as it does not interfere with... 

Many of the charcoal tube methods are based on NIOSH Method P CAM 127 (4) for organic solvents. In this method, a known volume of air is drawn through a charcoal tube to trap organic vapors, the charcoal is transferred to a vial, and the sample is desorbed with carbon disulfide. The sample is analyzed by gas chromatography (GC) with flame ionization detection (FID). Most methods use CS2 as the desorption solvent because it yields good recoveries from charcoal and produces a very low flame response. 

As methods of preparation, only the first three need be considered. It was decided not to try the direct action of bromine upon naphthalene, owing to the necessity of stirring the solid naphthalene and of collecting the hydrogen bromide gas the latter difficulty is also presented when carbon disulfide is used, and the objectionable properties of this solvent make its use further unfavorable. The third method, in which a suspension of naphthalene in alkaline hypobromite solution is treated with hydrochloric acid in aqueous solution, was found to give satisfactory results in so far as the yield of a-bromonaphthalene is concerned (though it was no better than with the method above described), but it presented considerable difficulties in the recovery of the hydrobromic acid. 

Figure 19.15. The liquid thermal diffusion system for the recovery of heavy sulfur isotope in carbon disulfide. The conditions prevailing at the time after 90% 34S is reached. Each rectangle in the cascades represents a column, each height being proportional to the length of the column. The two cascades have a combined height of 14 m, annular dia 25.4 mm, and annular width 0.18-0.3 mm. Production rate of 90% concentrate of 34S was 0.3 g/day [IV. M. Rutherford, Ind. Eng. Chem. Proc. Des. Dev. 17, 17-81 (1978)].

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