Oxidační procesy v bentonitových směsích

Processes of Oxidation in Bentonite Sands

conference paper

en

A new technology of physically and chemically treatment of green sand system, which contain water with radical oxidants is not yet used in Czech foundries. U.S. foundries have already started to exploit Advanced Oxidation technologies with very good results. Therefore the Department of Foundry Engineering of BUT investigated the influence of radical oxidants in green sand systems. The treatment is based on effects of oxidants and external sources of energy reacting with water and components in molding sands. Organic compounds of pyrolytic reaction of seacoal, resin binders, deactivated bentonite and other substances contaminate the molding sands. The oxidants (ozone and hydrogen peroxide) in ultrasonic aditated water, and added to bentonite sand by mulling, will react with and destroy these deposits. This cleaning of the particles will allow for better clay and sand particle interaction and binding with increasing the sand strength. The green compressive strength of production bentonite sand has been improved up to 23 %, the performance in molding system has been better. Introduction of complex oxidants technique into the foundry sands enables the elimination of noxious combustion products and other material originating by contact with cast metal. The AO treatment induced drops of 77 % benzene, 73 % of toluene, 91 % of ethylbenzene, 94 % of m + p-xylene, 95 % of o-xylene, 95 % of naphthalene and other polyaromatic molecules A new process is presumed to be a part of the no-waste technologies acceptable from the point of view of environmentally benign conditions in the foundry workshop (priority in EU).

Úpravy vodných roztoků pokročilými oxidačními procesy spočívají ve využití oxidačního účinku ozonu, případně ozonu v kombinaci s peroxidem vodíku a externím zdrojem energie (UV záření, ultrazvuk apod.). Cílem předložené práce bylo dosažení maximálního oxidačního účinku roztoku, který prostřednictvím molekulárního ozonu, ale především hydroxylových radikálů, oxiduje organické kontaminanty adsorbované na velkém měrném povrchu krystalků montmorillonitu, čímž dochází k obnovení jeho pojivových vlastností a k úspoře surovin při výrobě forem. Příznivé výsledky těchto měření potvrzují ekologické přednosti aplikace AOPs ve slévárenství a nabízejí možnost výrazného snížení finančních nákladů na výrobu forem úsporami nových materiálů, daných zvýšením pevnosti směsi obnovením pojivových vlastností bentonitu. Z těchto důvodů představují pokročilé oxidační procesy inovační technologii výroby forem, mající vysoký ekologický i ekonomický potenciál splňující přísné nároky na výrobu odlitků v EU.

A new technology of physically and chemically treatment of green sand system, which contain water with radical oxidants is not yet used in Czech foundries. U.S. foundries have already started to exploit Advanced Oxidation technologies with very good results. Therefore the Department of Foundry Engineering of BUT investigated the influence of radical oxidants in green sand systems. The treatment is based on effects of oxidants and external sources of energy reacting with water and components in molding sands. Organic compounds of pyrolytic reaction of seacoal, resin binders, deactivated bentonite and other substances contaminate the molding sands. The oxidants (ozone and hydrogen peroxide) in ultrasonic aditated water, and added to bentonite sand by mulling, will react with and destroy these deposits. This cleaning of the particles will allow for better clay and sand particle interaction and binding with increasing the sand strength. The green compressive strength of production bentonite sand has been improved up to 23 %, the performance in molding system has been better. Introduction of complex oxidants technique into the foundry sands enables the elimination of noxious combustion products and other material originating by contact with cast metal. The AO treatment induced drops of 77 % benzene, 73 % of toluene, 91 % of ethylbenzene, 94 % of m + p-xylene, 95 % of o-xylene, 95 % of naphthalene and other polyaromatic molecules A new process is presumed to be a part of the no-waste technologies acceptable from the point of view of environmentally benign conditions in the foundry workshop (priority in EU).

Advanced oxidation processes, Ozone, Hydrogen peroxide, Sonochemistry

2005

14.09.2005

University of Ljubljana

Ljubljana

Conference Proceedings

1

12