# US 5,704,490 A · Electrostatic separation of particulate material > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,704,490 A - Document ID: US5704490A - Status: Granted - Kind: A - Application number: 08/455,324 - Filed: 1995-05-31 - Granted: 1998-01-06 - Earliest claimed: 1994-06-17 - Assignees: British-American Tobacco Company Limited - Inventors: Joseph Robert Reynard - Web page: https://patentgrep.com/patent/US5704490A ## CPC - B03C 7/06: with cylindrical material carriers - B03C 7/00: Separating solids from solids by electrostatic effect - B03C: MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS (separating isotopes B01D59/00; combinations of magnetic or electrostatic separation with separation of solids by other means B03B, B07B) ## Abstract Electrostatic separation is used to separate electrically conducting particles from electrical insulator particles by attracting the conducting particles to a separating electrode, whilst the insulator particles remain substantially attached to a carrier electrode. The electrical properties of the particles to be separated can be enhanced or even changed by controlling the moisture content of the particles to be separated. ## Claims ### Claim 1 A method of separating electrically conducting carbon particles from electrical insulating tobacco particles, the moisture content of the tobacco supplied to the carrier electrode being less than 12%, the method comprising the steps of passing a mixture of carbon particles and tobacco particles onto a rotating carrier electrode having an electrically conducting surface, a corona discharge device disposed above the carrier electrode providing an electrical charge to the particles, the charged electrically conducting particles discharging to the electrically conducting surface of the carrier electrode, which electrode is earthed, the discharged carbon particles being attracted towards a separating electrode the arrangement of the separating electrode being such as to laterally separate the carbon particles from the tobacco particles. ### Claim 2 (depends on 1) A method according to claim 1, wherein the electrical insulator particles are at a moisture content of less than 10%. ### Claim 3 (depends on 1) A method according to claim 1 wherein the electrical insulator particles are at a moisture content of less than 8%. ### Claim 4 (depends on 1) A method according to claim 1, wherein the electrically conducting particles are at a moisture content of greater than 10%. ### Claim 5 (depends on 1) A method according to claim 1, wherein the moisture content of the tobacco particles supplied to the carrier electrode is less than 8%. ### Claim 6 An electrostatic separation apparatus for separating an electrically conducting particulate material from an electrical insulator particulate material, the apparatus comprising a rotating carrier electrode having an electrically conducting surface, disposed above which electrode is supply means for the particles to be separated and a corona discharge device, the corona discharge device comprising a series of corona discharge pins, the corona discharge device being connected to a high voltage electrical supply and being operable to provide an electrical charge to the particles to be separated, disposed in lateral relationship to the carrier electrode and the discharge device is a separating electrode positioned to attract discharged electrically conducting particulate material, the separating electrode being a charged electrode plate, and the voltage supplied to the corona discharge device being of the same potential as the voltage supplied to the carrier electrode. ### Claim 7 (depends on 6) Apparatus according to claim 6, wherein the rotating carrier electrode is a rotating drum. ### Claim 8 (depends on 6) Apparatus according to claim 6, wherein the carrier electrode is of the same width as the supply means. ### Claim 9 (depends on 6) Apparatus according to claim 6, wherein a scraper is provided to remove electrical insulator particles from the carrier electrode. ### Claim 10 (depends on 6) Apparatus according to claim 6, wherein heating means is disposed at said supply means to heat the particles to be separated. ### Claim 11 (depends on 6) Apparatus according to claim 6, wherein moistening means is disposed either above a conveyor disposed at a downstream end of the separation apparatus to moisten dried separated particles or above a conveyor at an upstream end of the apparatus to moisten particles before separation. ### Claim 12 A method of separating electrically conducting tobacco particles from electrically insulating filtration material particles, the moisture content of the tobacco particles supplied to a carrier electrode being greater than 10%, the method comprising the steps of passing a mixture of carbon particles and tobacco particles onto a rotating carrier electrode having an electrically conducting surface, a corona discharge device disposed above the carrier electrode providing an electrical charge to the particles, the charged electrically conducting particles discharging to the electrically conducting surface of the carrier electrode, which electrode is earthed, the discharged carbon particles being attracted towards a separating electrode, the arrangement of the separating electrode being such as to laterally separate the carbon particles from the tobacco particles. ### Claim 13 (depends on 12) A method according to claim 12, wherein the electrically conducting particles are at a moisture content of greater than 13%. ### Claim 14 (depends on 12) A method according to claim 12, wherein the moisture content of the tobacco particles supplied to the carrier electrode being greater than 13%. ### Claim 15 A method of separating electrically conducting carbon particles from electrically insulating filtration material particles, the method comprising the steps of passing a mixture of carbon particles and tobacco particles onto a rotating carrier electrode having an electrically conducting surface, a corona discharge device disposed above the carrier electrode providing an electrical charge to the particles, the charged electrically conducting particles discharging to the electrically conducting surface of the carrier electrode which electrode is earthed, the discharged carbon particles being attracted towards a separating electrode, the arrangement of the separating electrode being such as to laterally separate the carbon particles from tobacco particles. ### Claim 16 A method of separating electrically conducting tobacco particles from electrically insulating material particles, the moisture content of the tobacco particles supplied to the carrier electrode being greater than 10%, the method comprising the steps of passing a mixture of carbon particles and tobacco particles onto a rotating carrier electrode having an electrically conducting surface, a corona discharge device disposed above the carrier electrode providing an electrical charge to the particles, the charged electrically conducting particles discharging to the electrically conducting surface of the carrier electrode, which electrode is earthed, the discharged carbon particles being attracted towards a separating electrode, the arrangement of the separating electrode being such as to laterally separate the carbon particles from the tobacco particles.