Separation of granular particles

A system for separating granular particles according to particle size, said granular particles being derived from bulk granular solids, bulk ores or ores recovered from host rocks where they occur as veins of mineralisation, said bulk granular solids, bulk ores or recovered ores having been subjected to initial conditioning by primary crushing, said system comprising:

• a conveyor for transporting granular material comprising multiple sized fractions with gradation of particles in said granular material according to particle size between relatively fine fractions and relatively coarse fractions in a direction having a horizontal component and subjecting said granular material to vibration while being so transported to induce some separation of particles according to particle size, with a portion of said relatively fine fractions underflowing said relatively coarse fractions, said conveyor causing said granular material to subsequently move as a granular flow outwardly and downwardly along a curved path through the air under the influence of gravity to further induce separation of particles according to particle size;
• a separator for dividing said granular flow moving along the curved path into at least two parts according to the trajectory of constituent particles, and
• a surface plate presenting a surface to at least one of said two parts to flow downwardly along said surface plate under the influence of gravity, said surface plate being configured to allow the flow of said one of said two parts to spread laterally across the width of said surface plate, with particles travelling at different speeds according to particle size such that relatively coarser particles overflow relatively finer particles, thereby facilitating further gradation between relatively fine fractions and relatively coarse fractions, said surface plate being inclined at an angle to the flow path of said one of said two parts, said angle being selected to be inclined at an angle just above an adopted stall angle for said granular flow thereby permitting constituent particles of said one of said two parts to continue to flow, the flow of particles in said one of said two parts being adjusted by reason of differences in effective friction between said particles in said one of said two parts which leads to differential speeds between particles in said one of said two parts with finer particles in said one of said two parts underflowing larger particles and facilitating said lateral spread of said one of said two parts across the width of said surface plate, whereby to induce separation of said granular particles according to particle size.

A method for enhancing ore grades by removing unwanted material from bulk granular solids, bulk ores or ores recovered from host rocks where they occur as veins of mineralisation, said bulk granular solids, bulk ores or recovered ores having been subjected to initial conditioning by primary crushing, said method comprising:

• transporting said crushed ore with gradation of particles of said crushed ore between relatively fine fractions and relatively coarse fractions in a direction having a horizontal component and subjecting said crushed ore to vibration, while being so transported to induce some separation of particles according to particle size;
• causing said crushed ore to move as a granular flow outwardly and downwardly along a curved path through the air under the influence of gravity to further induce separation of particles according to particle size with at least a portion of said relatively fine fractions underflowing said relatively coarse fractions;
• dividing said granular flow moving along the curved path into at least two parts according to the trajectory of constituent particles, and
• presenting at least one of said two parts to a surface to flow downwardly along said surface under the influence of gravity, said surface being configured to allow the flow of said one of said two parts to spread laterally across the width of said surface, with particles in said one of said two parts travelling at different speeds according to particle size such that relatively coarser particles overflow relatively finer particles, thereby facilitating further gradation between relatively fine fractions and relatively coarse fractions, said surface being inclined at an angle to the flow path of said one of said two parts, said angle being selected to be inclined at an angle just above an adopted stall angle for said granular flow thereby permitting constituent particles of said one of said two parts to continue to flow, the flow of particles in said one of said two parts being adjusted by reason of differences in effective friction between said particles in said one of said two parts which leads to differential speeds between particles in said one of said two parts with finer particles in said one of said two parts underflowing larger particles and facilitating said lateral spread of said one of said two parts across the width of said surface, whereby to induce separation of said granular particles according to particle size and removing unwanted material.

A system for enhancing ore grades by removing unwanted material from bulk granular solids, bulk ores or ores recovered from host rocks where they occur as veins of mineralisation, said bulk granular solids, bulk ores or recovered ores having been subjected to initial conditioning by primary crushing, said system comprising;

• a conveyor for transporting said crushed ore with gradation of particles of said crushed ore between relatively fine fractions and relatively coarse fractions in a direction having a horizontal component and subjecting the crushed ore to vibration while being so transported to induce some separation of particles according to particle size, said conveyor causing said crushed ore to move as a granular flow outwardly and downwardly along a curved path through the air under the influence of gravity to further induce separation of particles according to particle size with at least a portion of said relatively fine fractions underflowing said relatively coarse fractions;
• a splitter for dividing said granular flow moving along said curved path into at least two parts according to the trajectory of constituent particles, each of said at least two parts having different trajectories following splitting, and
• a surface plate presenting a surface to at least one of said two parts to flow downwardly along said surface under the influence of gravity, said surface being configured to allow the flow of said one of said two parts to spread laterally across the width of said surface, with particles in said one of said two parts travelling at different speeds according to particle size such that relatively coarser particles overflow relatively finer particles, thereby facilitating further gradation between relatively fine fractions and relatively coarse fractions, said surface being inclined at an angle to the flow path of said one of said two parts, said angle being selected to be inclined at an angle just above an adopted stall angle for said granular flow thereby permitting constituent particles of said one of said two parts to continue to flow, the flow of particles in said one of said two parts being adjusted by reason of differences in effective friction between said particles in said one of said two parts which leads to differential speeds between particles in said one of said two parts with finer particles in said one of said two parts underflowing larger particles and facilitating said lateral spread of said one of said two parts across the width of said surface, whereby to induce separation of said granular particles according to particle size and removing unwanted material.