The impact of cuprous acetylide on copper washing operations
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Our unit’s copper washing tower often experiences liquid carryover and abnormal liquid levels, which prevents production from proceeding. During shutdowns for maintenance, reddish-brown deposits were found on the packing; could this be cuprous acetylide? What impact does cuprous acetylide have on the operation of the copper washing process?
Cuprous acetylide, cuprous sulfide, and ferric ions are all reddish-brown; you can rule them out one by one. This is a precipitate that can cause copper washing in the copper melt.
It is estimated that both copper sulfide and cuprous sulfide precipitates are present; the color is merely indicative of the main components. These precipitates exist as fine powders floating on the surface of the copper melt. When gas comes into contact with the liquid, bubbles are formed, which create an artificial liquid level and affect the efficiency of copper cleaning. Moreover, it is difficult to completely remove these precipitates, so regular replacement is necessary
Although cuprous acetylide, cuprous sulfide, and ferric trivalent are all reddish-brown in color, it is not difficult to distinguish cuprous acetylide. Cuprous acetylide has a strong foaming property; if there is a large amount of it in the copper melt, the copper tower can easily accumulate liquid； Cuprous acetylide has a very low ignition point; dry cuprous acetylide during maintenance can catch fire with just the slightest touch, posing a serious risk of injury.
How is cuprous acetylide formed? ? ? ?
Molecular formula: CuC≡CH. Properties: The scientific name is cuprous acetylide. Pale orange solid. Relative density 4.62. Insoluble in water. Unstable; prone to explosion when heated or impacted. At -45°C, it decomposes into acetylene and dark red cuprous acetylide (Cu2C2). It can be decomposed by inorganic acids to regenerate acetylene. When producing gas from the coal of a specific coal mine, the gas contains acetylene, which reacts with copper ions in the copper melt to form copper acetylide, leading to foaming. It is recommended that the original poster start looking for the cause of the problem from the following aspects: 1. Has there been any change in the route for purchasing raw materials before liquid is introduced? If there has been no change, then the problem of bubbling and liquid presence caused by the formation of copper acetylide can likely be ruled out. It is impossible for there to be such large differences in coal quality at the same coal purchasing site. 2. There is too much reddish-brown precipitate, with copper sulfide being the main culprit. It is recommended to check the operation of the desulfurization process, especially the fine desulfurization system. 3. Do not neglect the management of the quality of the copper melt; regular filtration and oil removal must be part of an established long-term system. Ensure the long-term stability of the copper washing system.
In low steam-to-gas ratio conditions, Fe-Cr high-temperature shift catalysts exacerbate the Fischer-Tropsch reaction, leading to the production of larger amounts of acetylene; this acetylene reacts with copper when passing through copper-based hydroformylation catalysts to form copper acetylide. The foaming capacity of copper acetylide in molten copper is 50 times that of cuprous sulfide.
In addition to removing trace amounts of carbon monoxide, the copper washing section can also remove trace amounts of carbon dioxide and hydrogen sulfide. The main impact of cuprous acetylide on the copper cleaning process is the formation of bubbles in the copper melt, leading to liquid contamination incidents during production.