Apparatus for removing no-bake coatings from foundry sand and classifying the reclaimed sand

In an apparatus for removing no-bake rigid coatings encasing no-bake foundry sand and classifying the reclaimed sand grains according to particle size after the no-bake foundry sand has been comminuted to coated sand grain particle size, having means for fluidizing and conveying said sand grains size coated sand grains in a conduit to said apparatus at velocity just sufficient for pneumatic transport, the improvement comprising,

• a chamber having a coated sand grain inlet thereto
• said inlet arranged to direct a generally horizontal stream of no-bake sand particles into said chamber at the same velocity as the velocity at which the particles were transported in fluidized state
• a rigid target in said chamber positioned and arranged in said chamber on the opposite side from said inlet such that the rigid surface thereof is impacted by said stream coated particles such that by the energy of impact the coatings are fractured and form a downwardly directed curtain of uncoated sand and fractured coatings lying between and below said inlet and said rigid target,
• a first means adjacent said target for removing fractured no-bake coatings particles,
• a second means further removed from the target to complete the removal of fractured coating particles by inducing fluidizing air flow through a curtain of falling uncoated sand and fractured coatings at a velocity sufficient to separate fractured coatings and fine sand particles from sand grains of desired particle size and,
• exit means from said chamber for separately discharging the re-useable sand grains of desired particle size and fractured coatings and fine sand particles.

In an apparatus for removing no-bake rigid coatings encasing no-bake foundry sand and classifying the reclaimed sand grains according to particle size after the no-bake foundry sand has been comminuted to coated sand grain particle size, having a means for fluidizing and conveying said sand grain size coated sand grains in a conduit, to said apparatus at a velocity just sufficient for pneumatic transport, the improvement comprising:

• a chamber having a coated sand grain inlet thereto
• said inlet arranged to direct a generally horizontal stream of coated sand particles into said chamber at the same velocity as the velocity at which said particles were transported in a fluidized state,
• a rigid target having a concave wear resistant impact surface at least as large as the cross-sectional area of the stream of no-bake coated sand particles that will impact against it, arranged in said chamber on the opposite side from said stream of coated particles such that by the energy of impact the coatings are fractured and form a downwardly directed curtain of uncoated sand and fractured coatings lying between and below said inlet and said rigid target,
• a vent from said chamber located above said inlet in the upper portion of the chamber for exhausting fractured coating particles from said chamber, at least one ramp located below the target for descent of fractured coatings and uncoated sand particles falling from the target to the lower portion of the chamber,
• an adjustable flow gate located at the remote end of the last ramp for controlling the quantity of sand and fractured coatings that can pass over the edge of the ramp as a curtain of falling sand, a passageway located below the remote edge of the last ramp through which the sand falls,
• means for inducing air flow through the curtain of falling sand and coatings at velocity sufficient to separate fractured coatings and fine sand particles from the particle fall, so that only sand grains of desired particle size pass beyond the induced air flow, the induced air flow being in the range of perpendicular to the line of sand to approximately an angle of 45.degree. in a quadrant counter to the direction of the flowing sand,
• a regulating means cooperating with said passageway to control the velocity of the induced air flow across the curtain of falling sand, said regulating means including an adjustable member for controlling the cross-sectional area of the passageway at the point at which the air flow is induced, and an exit means from said chamber for separately discharging the re-useable sand grains of desired particle size and the fractured no-bake coatings and fine sand particles.