Abstract: An improved recycling apparatus for particulate asphaltic concrete comprises a rotatable drum in which the particulate composition is gradually heated between an input end and an output end having a retractable chute extending into a port at the output end for recovering composition of a selected temperature. The chute contains a temperature sensing device, and the apparatus preferably includes a drive means for inserting or retracting the chute, and thermostat means for selecting a product temperature whereby the drive means causes the chute to be extended into the drum to recover the composition of a selected temperature. In another embodiment, the drum includes first, second, and third lifters each extending along different respective lengths of the drum interior to achieve different exposure of the particulate composition to the heating gases in the drum in the respective different drum sections to achieve improved heating and mixing efficiency.

Abstract: A system and method for rapid beneficiation of bentonite clay is disclosed. Beneficiation of the bentonite clay occurs through oxidation of structural ferrous iron. For rapid beneficiation, bentonite clay, preferably ground, is subjected to moist air while the clay is being agitated, preferably by tumbling within a rotating drum, to provide rapid exchange of moisture and oxygen in the air with the bentonite clay aggregates to thereby increase the speed of oxidation of ferrous iron in the bentonite clay. Drying of the thus treated bentonite clay may be then achieved by agitating the clay, again preferably by tumbling within a rotating drum, in the presence of dry air.

Abstract: A method is disclosed for fixing certain dangerous substances into recyclable waste foundry sand so that they are less likely to leach out into the environment. The method uses a roasting process which causes the dangerous substances to form insoluble compounds with the sand. One example is shown where hazardous waste foundry sand which contains acetic acid soluble lead contamination is treated by this method. In this example the lead is believed to react with the sand during the roasting process forming compounds such as lead silicate which are insoluble to acetic acid. The amount of lead which may be leached out into the environment is reduced to a safe level according to the currently accepted test methods promulgated by the U.S. Environmental Protection Agency. The method may be applied to the conversion of waste foundry sand into reusable sand or landfill which are less likely to leach dangerous substances into the environment.

Abstract: A batch method of producing asphalt-aggregate composition having a temperature of at least about 200.degree. F. and at least about 20% used asphaltic concrete comprises heating solid particles of the used material in a first drum to a temperature of at least about 150.degree. F., separately heating virgin aggregate in a second drum to a temperature of less than about 400.degree. F., and mixing the two materials, preferably with the addition of hot liquid or paving grade asphalt. In a second embodiment, unheated used asphaltic concrete is mixed with heated used asphaltic concrete and heated virgin aggregate.

Abstract: A method and apparatus are disclosed which reduce smoke emissions in an asphalt drum mixer. A drum mixer heats virgin aggregate to a relatively high temperature in a first drying zone. Virgin asphalt and, in some cases, recycled pavement material containing asphalt, are added in a second zone. Mixing and discharge of the materials occur in a third zone. The invention provides for air or water cooling of the gases in the drum mixer upstream of the point of entry of the asphalt. This cooling reduces the formation of smoke which would otherwise be generated by excessive heating of the asphalt. The apparatus, according to a preferred embodiment, employs an axially positioned air duct, the outlet end of which discharges cooling air into the drum just upstream of the area of entry of the recycled material.

Abstract: An improved apparatus for recycling asphaltic concrete comprises a rotatable drum having a first port at one end open to atmosphere, a burner adjacent the first end, a second port at a second end of the drum with means for closing the second port, means for recovering the composition from the second port and whereby the closure means and composition recovery means at the second port cooperate to maintain the second port closed except to the extent necessary to recover composition.

Abstract: A method of hot mix recycling of old asphaltic concrete paving heats the old pavement, after it has been removed and sized, to a temperature below its firing point and heats fresh aggregate to a greater temperature before combining the two and adding new asphalt. The method is embodied in a drum-mixer type of apparatus modified by inserting a smaller drum in the upstream portion of the large drum. The burner fires into the smaller drum into which the fresh aggregate only is introduced while the old mix (plus additional fresh aggregate in certain cases) is introduced into the annular space between the two drums, the fresh aggregate and the old mix being thereafter combined in the large drum, new asphalt added and the mix further heated.

Abstract: An improved process for cleaning asphaltic concrete recycle gases comprises introducing a flame into the exhaust gas stream at the opposite drum end that heating gases are introduced.

Abstract: In a continuous drum mix asphalt plant, dust is exhausted from an intermediate zone of the drum mixer between its drying and mixing zones. The dust is exhausted radially through openings into a collection housing, which communicates with a dust collector and exhaust blower. An end housing at the discharge end of the drum communicates with the same dust collector and blower. Dampers are provided to control the relative proportion of air exhausted from the drum through the respective housings. Aggregate deflectors on the interior wall of the drum at the intermediate zone allow air and dust to flow while inhibiting the flow of aggregate. The collection housing surrounding the intermediate zone is of a size such as to produce a reduction in the velocity of the air as it passes out of the drum. Consequently, it serves as a knock-out box for the collection of larger particles which are carried out of the drum, but which settle out of the air stream as a result of the velocity decrease.

Abstract: An apparatus for heating and mixing an asphalt-aggregate composition comprises a drum rotatable about an axis, having a mixing and heating chamber with a restricted port at one end into which a flame and hot gases of combustion are directed and through which exhaust gases concurrently pass to atmosphere. A heating means comprises a burner for directing flame and the hot gases of combustion into the chamber at the restricted port along the drum axis of rotation and which burner is adjustable relative to the port along the drum axis of rotation. A burner assembly includes an air duct having an air entrainment port located away from substantial exposure to the drum exhaust gases. The drum includes a plurality of pegs extending into the drum chamber. Heating is carried out in a rotating drum without forming a veil or curtain of particulate composition through the hot gases of combustion.

Abstract: An improved apparatus for recycling asphaltic concrete includes an inclined chute for introducing composition into an open port into which a burner also feeds hot gases of combustion. The apparatus provides for improved continuous processing by feeding composition containing relatively large particle sizes into the open port and recovering heated composition adjacent the opposite drum end.

Abstract: A method and apparatus for treating paving material wherein the asphalt material is tumbled within an inclined drum so that it initially passes through the center portion of a stream of hot gases and is conveyed rearwardly and then is subsequently dropped through a more peripheral portion of the hot gas stream and conveyed rearwardly at a faster rate than it was initially. The apparatus comprises a wheeled frame, an elongated drum having a cylindrical inner surface and which is supported on the frame for rotational movement about its longitudinal axis, a feed chute communicating with the inlet end of the drum, and LP gas burners mounted at the opposite end of the drum so as to direct a flame and stream of hot gas centrally through a drum toward the inlet. A plurality of flights are secured to the drum inner surface which extend radially inward toward the drum longitudinal axis and extend rearwardly in a direction parallel to the axis.

Abstract: A process and an apparatus for cooling and handling sand in which hot used sand is delivered to a mixer and mixed with cooler sand. The mixed sand is discharged from the mixer for circulation on conveyor means for further cooling and the cooled sand is separated into a first fraction for discharge to successive milling and moulding stages and a second fraction for return to the mixer to effect sand mixing with the hot used sand. Water may be added to the mixed sand in the mixer to adjust the moisture content and to increase cooling.