Coal preparation process and magnetite reclaimer for use therein

Claim 1

Apparatus for separating finely sized high gravity magnetic material from a liquid medium having non-magnetic solids carrying the magnetic material on their surface, and ultra-fine nonmagnetic particles, comprising in combination: a. a tank structure for maintaining a liquid bath having an inclined bottom wall establishing an upper and lower end of the tank, said tank having a feed inlet passage at the lower end for admitting the liquid medium a discharge outlet passage for the non-magnetic solids at the upper end, a liquid supply adjacent the upper end of said tank, and an overflow weir adjacent the lower end of said tank, whereby a constant flow of liquid can be maintained through the tank and the ultra-fine non-magnetic particles which are carried into the tank with the said non-magnetic solids and which become suspended in the liquid bath can be removed from the tank over the overflow weir; b. agitating means in the tank for abrasively agitating the nonmagnetic solids in the liquid bath, said agitating means including at least two counter-rotating shafts parallel to the inclined bottom wall of the tank, each shaft having a lower section with a plurality of agitating paddles mounted in a helical configuration followed by a helical plate screw blade, said paddles and said screw blade on one shaft being of opposite hand to those on the other shaft so the material in contact with said paddles and said screw blade will be conveyed in the same direction toward the discharge outlet for the nonmagnetic solids, the counter rotation of said agitating paddles mixing and throwing the solids into abrasive scrubbing contact with each other in a region between the respective shafts to thereby dislodge the finely sized magnetic material from the surface of the solids; and c. a magnetic drum separator rotatably mounted about a horizontal axis and positioned vertically above the agitating paddles in the lower end of the tank with the longitudinal axis of said drum separator parallel to the longitudinal axis of said counter-rotating shafts of said agitating means, said drum separator having a non-magnetic cylindrical wall extending below the surface of the liquid bath into the region above and between the counter-rotating agitating paddles, said drum separator further having an elongated magnet of arcuate cross section stationarily mounted adjacent the interior surface of said drum wall so the magnetic field of the magnet is effective on the portion of the drum wall passing through the liquid bath to thereby attract the freed magnetic particles suspended in the agitated liquid medium to the outer surface of the drum.

Claim 8

An apparatus for separating finely sized high gravity magnetic material from a liquid medium having non-magnetic solids carrying magnetic material on their surface and having ultra-fine non-magnetic particles and for removing the magnetic material from the apparatus separately from the solids and the ultra-fine particles, comprising in combination: a. an outer cylindrical shell having frusto-conical end housings and an inner concentric cylindrical drum connected to said outer shell arranged so that a liquid bath can be retained in the shell, one end housing having a central feed inlet opening and the other end housing having a central discharge opening, said inner drum having a wall portion extending below the surface of the liquid bath; b. means for rotating said shell about a substantially horizontal axis; c. a plurality of lifters disposed in a helical pattern and attached to the inner surface of said shell, said lifters lifting and tumbling the solids in the liquid bath as the shell is rotated so the solids are thrown against each other in an abrasive scrubbing action to release the magnetic material from the surface of the solids and to suspend the magnetic particles in the liquid bath, said helical pattern of said lifters advancing the solids toward said discharge opening; and d. an elongated magnet of arcuate cross section stationarily mounted adjacent the interior wall portion of said inner drum so the magnetic field of said magnet is effective on the portion of the drum wall passing through the liquid bath to thereby attract the freed magnetic material, suspended in the agitated liquid medium, to the outer surface of said rotating inner drum, the uppermost extent of said arcuate magnet on the upwardly turning side defining a discharge position for the magnetic material.

Claim 9

An apparatus for separating finely sized high gravity magnetic material from a liquid medium having non-magnetic solids carrying magnetic material on their surface and having ultra-fine non-magnetic particles and for removing the magnetic material from the apparatus separately from the solids and the ultra-fine particles, comprising in combination: a. an outer cylindrical shell having frusto-conical end housings and an inner concentric cylindrical drum connected to said outer shell arranged so that a liquid bath can be retained in the shell, one end housing having a central feed inlet opening and the other end housing having a central discharge opening, said inner drum having a wall portion extending below the surface of the liquid bath; b. means for rotating said shell about a substantially horizontal axis; c. a plurality of lifters disposed in a helical pattern and attached to the inner surface of said shell, said lifters lifting and tumbling the solids in the liquid bath as the shell is rotated so the solids are thrown against each other in an abrasive scrubbing action to release the magnetic material from the surface of the solids and to suspend the magnetic particles in the liquid bath, said helical pattern of said lifters advancing the solids toward said discharge opening; and d. an elongated magnet of arcuate cross section stationarily mounted adjacent the interior wall portion of said inner drum so the magnetic field of said magnet is effective on the portion of the drum wall passing through the liquid bath to thereby attract the freed magnetic material, suspended in the agitated liquid medium, to the outer surface of said rotating inner drum, the uppermost extent of said arcuate magnet on the upwardly turning side defining a discharge position for the magnetic material.