Apparatus for decontaminating soils

An apparatus which is selectively operable for either producing asphalt suitable for highway construction or for the decontamination of petroleum contaminated soils and the like, and comprising

• a rotary drum mixer which includes burner means for delivering heated air into the interior of the mixer, drive means for rotating the mixer about a fixed rotational axis, an inlet adjacent one end of the mixer for receiving a particulate material to be processed, a first outlet adjacent the other end of the mixer for the delivery of the material therefrom, and a second outlet for the removal of gasses from the interior of the mixer, said rotational axis of said drum mixer being inclined from the horizontal, and with said one end being elevated with respect to said other end of said mixer, and wherein said mixer includes internal vane means for lifting the cascading the particulate material during rotation of the mixer and as the material moves from one end toward said other end,
• means for selectively applying liquid asphalt or the like to the material processed in said mixer,
• a baghouse having means for cleaning particulates from an airstream passing therethrough,
• an incinerator having means for heating an airstream passing therethrough to a temperature sufficient to effectively incinerate vaporized contaminants therein, said incinerator including means for selectively introducing a controlled amount of ambient air into the airstream passing therethrough,
• means for delivering the airstream from said incinerator to said baghouse and including means for sensing the temperature of the airstream, and means responsive to said sensing means for introducing a water spray into the airstream to reduce the temperature thereof before it enters said baghouse,
• first air duct means for conveying the heated gasses from said second outlet of said mixer to said baghouse,
• second air duct means for conveying the heated gasses from said second outlet of said mixer to said incinerator, and
• valve means for selectively opening either one of said first or second air duct means while closing the other of said air duct means.

A method of selectively producing asphalt suitable for highway construction, or decontaminating petroleum contaminated soil or the like, and comprising the steps of

• heating and drying stone aggregate in a rotary drum mixer by contacting the same with heated gases, and while applying liquid asphalt to the heated and dried aggregate,
• conveying the heated gases through a first air duct from the rotary drum mixer to a baghouse wherein the gases are filtered and released to the atmosphere, and thereafter
• heating contaminated soil in said rotary drum mixer to a temperature above the volatilization temperature of the contaminants but below the autoignition temperature of the contaminants, and so as to volatilize the contaminants,
• conveying the volatilized contaminants through a second air duct to an incinerator and heating the volatilized contaminants therein to a temperature sufficient to effectively oxidize the volatilized contaminants and form non-toxic gaseous products, and then
• conveying the gaseous products from said incinerator to said baghouse, and such that the gaseous products are filtered and released to the atmosphere.