Molybdenum scrubbing

On molybdenum sulfate roasting, downstream of a scrubber, to remove ammonium sulfite and sulfate aerosols which form in the ammonia scrubbing stage, and SO2,... 

Before scrubbing procedures were established for copper ore, most of the rhenium was lost as the volatile (I Oy), A small portion, perhaps 10%, was retained in flue dust, which was processed to give the metal. A commercial flotation (qv) process for the recovery of the molybdenite by-product is available that permits a high recovery of molybdenum and rhenium. This process is used at the Caridad copper mine in Mexico. 

Investigation of non-ferrous metal chelates that can efficiently absorb NO and provide stability toward oxidation. Many cobalt, copper, manganese, molybdenum, nickel, osmium, rhenium, rhodium, ruthenium and vanadium chelates have been demonstrated to be able to coordinate NO. Their application to flue gas scrubbing systems should be explored. 

In a typical process, approximately stoichiometric quantities of propylene, ammonia and oxygen (as air) are fed into a reactor containing a fluidized catalyst, such as a bismuth, molybdenum or uranium containing compound. The reaction is conducted at 400-500°C and 1-3 atmospheres. The exit gases are scrubbed with water and acrylonitrile is obtained from the aqueous solution by a series of distillations. In a variation of this process, propylene is treated with nitric oxide (which may be regarded as a product of ammonia oxidation) at about 700°C in the presence of a silver catalyst ... 

Methanol is prepared by the interaction of carbon monoxide and hydrogen, usually at 300-400°C and 275-360 atmospheres. A catalyst of zinc oxide promoted with chromic oxide is generally employed and conversions of about 15% per pass are usual. The methanol is condensed out and unreacted gases, with fresh make-up gas, recycled to the converters. In the second stage, methanol is oxidized to formaldehyde. In one process a mixture of methanol vapour and air is passed over a catalyst of molybdenum oxide promoted with iron at 350—450°C. The exit gases are scrubbed with water and the formaldehyde is isolated as an aqueous solution. 

Once the raw has been scrubbed for soot removal, H2s is removed and CO is shifted across a cobalt molybdenum sour gas shift catalyst to adjust the H20/C0/C02 ratio. Finally, excess C02 is removed and the gas may be compressed (if required) and then processed in a conventional methanol synthesis loop. The processing steps as just described yield a syn that is approximately stoichiometric in nature (i 1.0) althou considerably more concentrated in CO than C02. 

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