Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C1/00—Magnetic separation
  • B03C1/02—Magnetic separation acting directly on the substance being separated
  • B03C1/30—Combinations with other devices, not otherwise provided for
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B1/00—Preliminary treatment of ores or scrap
  • C22B1/005—Preliminary treatment of scrap
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C2201/00—Details of magnetic or electrostatic separation
  • B03C2201/18—Magnetic separation whereby the particles are suspended in a liquid
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
  • B03C2201/00—Details of magnetic or electrostatic separation
  • B03C2201/20—Magnetic separation of bulk or dry particles in mixtures
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling

Definitions

• Steel mill sludge is material generated during the process of steelmaking that contains iron oxide.
• Steel mill sludge also referred to simply as “mill sludge,” is generally distinguished from mill scale by its finer particle size and higher oil content.
• mill sludge is generally distinguished from mill scale by its finer particle size and higher oil content.
• streams typically containing waste water, iron oxide based solids, oil and other hydrocarbon compounds. These streams are typically collected in a settling pit in which the stream separates into three phases, typically an upper oil phase or layer comprising the lighter free hydrocarbons, an aqueous layer or phase below the oil phase and a lower layer or phase comprising the mill sludge and mill scale
• the oil contamination present in the mill sludge is generally derived from the lubricants and coolants used in manufacturing the final steel products as well as lubricants from the process equipment that is exposed to elevated temperatures during the formation of the final steel products.
• This oil contamination throughout the mill sludge limits the potential for recycling the iron oxide containing sludge back into the steelmaking process.
• the heat involved in the steelmaking process liberates hydrocarbons and various oxides of
• mill sludge solids are characterized by particles having very fine diameters, typically on the order of that associated with fine silts and clays. The very small particles allow the oil molecules to form extremely tight bonds with the solid particles and/or within agglomerations of such particles.
• U.S. Patent No. 7,531,046, for example, discloses a process for treating an oily mixture consisting of hydrocarbons, solid particles, and water which includes the steps of placing the oily mixture into a reactor chamber, purging the reactor chamber with an inert gas, and creating a steam bath within the inert gas filled reactor chamber, the steam surge freeing hydrocarbon matter from the solid particles.
• the process further includes elevating reactor chamber temperature to a boiling point temperature corresponding to the
• the elevated temperature vaporizing the hydrocarbons are vaporized within inert atmosphere.
• the reaction chamber is vented and the off-gas is processed into a hydrocarbon product while the de-oiled solid particles are discharged from the reaction chamber as a raw material or for disposal.
• U.S. Patent No. 5,125,966 discloses a process for de-oiling mill sludge which comprises admixing the mill sludge with sufficient water and sufficient surface active agent to provide a slurry having at least 25 wt solids content and at least 4,000 ppm of surface active agent based on solids, subjecting the slurry to high shear agitation to form an oily water emulsion, and separating at least 40 wt of the solids from the oily water emulsion.
• Disclosed is a method for treating oil-containing particulates such as mill sludge comprising applying a treatment solution to a particulate feed stream to form a treated slurry, applying a mechanical disrupter to the treated slurry to reduce an average particulate size, applying a magnetic separator to the treated slurry to form a ferrous slurry, and applying a thermal separator to the ferrous slurry to extract a hydrocarbon portion and produce a ferrous product stream.
• This basic method may be modified in a number of ways including, for example, applying a sizing operation to the oil-containing particulates to remove larger particles from the particulate feed stream, condensing a volume of the hydrocarbon portion or using magnetic separators of varying strength to provide ferrous slurries of varying ferrous content.
• a range of treatment solutions can be utilized including, for example, solutions comprising a petroleum based softening agent, an emollient, a solubilizer and a coupling agent. These components may be present in varying quantities encompassing, for example, treatment solutions including 20 and 70 wt of a petroleum based softening agent, 2 and 50 wt of an emollient, 5 to 25 wt of a solubilizer and 1 and 10 wt of a coupling agent.
• the emollient may be a pH neutral emollient, but other embodiments of the treatment solution may include non-neutral emollients and/or pH adjusters and buffering agents.
• the petroleum based softening agent may include one or more hydrocarbon fuel composition(s), the emollient may include one or more glycols, the solubilizer may include one or more ethers and alcohols and the coupling agent may include one or more organic acids.
• An example treatment solution is one in which the petroleum based softening agent comprises diesel fuel, the emollient comprises polypropylene glycol, the solubilizer includes at least one compound selected from a group consisting of polyoxyethelene ether and polyoxyethelene alcohol, and the coupling agent comprises dicarboxylic acid.
• the disclosure also encompasses apparatus suitable for practicing the disclosed methods comprising an assembly of sizing, conveying, spraying, disrupting, separating, heating and condensing equipment arranged to perform the sequence of operations required to complete the method.
• FIG. 1 illustrates an example sludge preparation process and a corresponding example sludge preparation apparatus.
• FIG. 2 illustrates an example separation and recovery process and a corresponding example separation and recovery apparatus.
• the process and related apparatus disclosed herein provide an integrated industrial process that can be utilized for de-oiling steel industry and other oil-contaminated wastes to less than 2,000 ppm oil content. This process and apparatus enables the
• FIGS. 1 and 2 An example process and an example apparatus are illustrated in FIGS. 1 and 2 with a sludge preparation apparatus and method shown with respect to apparatus 100a of FIG. 1 and the separation and recovery apparatus and method shown with respect to apparatus 100b of FIG. 2.
• mill sludge or stabilized mill sludge 102 is withdrawn from a settling pond, reservoir, tank or other storage facility 101 and fed 102a to one or more scalping screen(s) 104 or other suitable separating device for removing oversized debris 104b, for example, those particles greater than 4 inches in diameter (10.2 cm).
• scalping screen(s) 104 or other suitable separating device for removing oversized debris 104b, for example, those particles greater than 4 inches in diameter (10.2 cm).
• the selection of the particular size classification and sorting technique(s) will be guided by a number of factors including, for example, the average particle size in the mill sludge, the particle size distribution and the capability of the downstream separation processes.
• That portion of the sludge feed 104a that passes through the screen 104 can then be fed into a crusher or mill 106 to further reduce the size of the particles for additional processing.
• the crushed sludge stream 106a can then be transferred via conveyor 108 to a second screen or other separator 110 to ensure that the remaining particles approach a suitable target size, for example, no more than 0.5 inch in diameter (1.3 cm).
• a suitable target size for example, no more than 0.5 inch in diameter (1.3 cm).
• Those particles in the crushed sludge stream 106a that are still above the target size for further processing can be feed back to the crusher through a recycle stream 110b or discarded.
• a washing system typically including a pump 118, washing chemical reservoir(s) 120 for a wetting agent chemical, an emollient chemical, a solubilizing chemical, and a coupling agent chemical, water source(s) 116, and metering pump(s) 122 capable of metering concentrations of, for example, up to 2.0 percent or more may be used for injecting the treatment chemicals 122a into a water feed 118a to produce a washing solution 118b.
• This washing solution is then sprayed 124 on the sludge as it passes over the screen 110 and/or injected into a slurry mixing tank 112.
• the screened sludge and the washing solution are combined and agitated to form a slurry 114 containing, for example, 35 wt solids.
• the slurry stream 112a is then pumped to a physical separator 126 for further processing.
• the physical separator 126 may, for example, operate on the venturi principal using high pressure fluid 128a, for example, water at 5,000 to 10,000 psi (344 to 689 bar), supplied by high pressure pump 128 to produce high speed water jets or streams and/or other mechanical and/or ultrasonic processes (not shown) known to those of ordinary skill in the art sufficient to reduce remaining aggregations of fine sludge particles to smaller aggregations and individual particles and form a processed slurry stream 126a.
• high pressure fluid 128a for example, water at 5,000 to 10,000 psi (344 to 689 bar
• high pressure pump 128 supplied by high pressure pump 128 to produce high speed water jets or streams and/or other mechanical and/or ultrasonic processes (not shown) known to those of ordinary skill in the art sufficient to reduce remaining aggregations of fine sludge particles to smaller aggregations and individual particles and form a processed slurry stream
• the selection of the particular separation technique(s) will be guided by a number of factors including, for example, the average particle size, the particle size distribution, the degree of agglomeration and the distribution of agglomeration degree within the slurry stream.
• the processed slurry stream 126a from physical separator 126 is then transferred to one or more wet drum magnetic separators 130, 130' configured for removing those particulates having a sufficiently high concentration iron and/or other magnetic metal from the processed slurry.
• the removed particulates 130a, the "solid" phase can then be subjected to further treatment in order to de-oil the separated solids.
• the "liquid" phase exiting the magnetic separator 130b typically includes water, oil and non-magnetic compounds not removed in the separators including, for example, graphite that may be treated using conventional wastewater treatment methods 134.
• the solid phase 130a exiting the magnetic separator consists generally of magnetic sludge containing iron and other metals still having some oil content.
• the magnetic sludge is transported to a low temperature extractor 132 operating at 600-800°F (316 to 427°C). As the magnetic sludge passes through the extractor 132, a portion of the oil remaining in the magnetic sludge is extracted to produce de-oiled sludge 132a exhibiting an oil content of less than 2,000 ppm (mg/kg).
• the de-oiled sludge 132a is suitable for recovery 146 and reuse of its iron content.
• the gas exhaust 132b from the low temperature extractor contains the separated oil, lighter organics and entrained water.
• the exhaust may be withdrawn from the extractor 132 by a blower 136 that moves the exhaust through a condenser 138.
• the condenser 138 oil separates from the exhaust.
• the exhaust and oil flow to a receiver tank 140.
• oil 140b is extracted for recovery processing 144 and the exhaust 140a can be directed to suitable off-gas treatment equipment 142.
• the invention can be constructed in different ways as long as the function performed by the equipment is achieved.
• multiple wet drum magnetic separators 130, 130' may be used depending on the nature of the iron particles in the sludge. Differing gauss strengths, and hence different wet drum separators, may be required to remove differing sizes of iron particles.
• the disclosure is not limited to the particular example embodiment illustrated and described herein.
• An example washing or treatment solution suitable for injection at 124 is a composition including a petroleum based softening agent, for example, diesel fuel, comprising between 20 and 70 wt ; an emollient, preferably a pH neutral emollient, for example, polypropylene glycol, comprising between 2 and 50 wt ; a solubilizer, for example, polyoxyethelene ether and/or polyoxyethelene alcohol, comprising between 5 to 25 wt ; and a coupling agent, for example, dicarboxylic acid , comprising between 1 and 10 wt .
• a petroleum based softening agent for example, diesel fuel, comprising between 20 and 70 wt
• an emollient preferably a pH neutral emollient, for example, polypropylene glycol, comprising between 2 and 50 wt
• a solubilizer for example, polyoxyethelene ether and/or polyoxyethelene alcohol, comprising between 5 to 25 wt
• the treatment solution may also contain pH adjuster(s) and/or buffering agents for controlling the pH of the solution. It is anticipated that in most instances a generally neutral pH will be sufficient but, depending on the nature and composition of the feed slurry, the pH of the treatment solution may be adjusted in order to achieve improved oil release and/or control the pH of the treated slurry solution that will be fed into the downstream processes.
• the various components of the washing solution can be handled separately and/or in one or more compositions, e.g., master batch formulation(s), to provide a wider range of compositions and/or simplify the process control respectively.
• the components of the washing solution have the combined effect of loosening the chemical bonds between oil and the solid particles and helping to mobilize the oil in preparation for disaggregation of the sludge particles in the physical separator 126.
• sludge preparation process and separation and recovery process and apparatus i.e., the front end and back end of a unified process and corresponding apparatus may be further modified for particular applications by taking into consideration such factors as the type of sludge, the hydrocarbon loading level and composition and the intended use of the processed sludge.
• equipment and process fluids may be adapted to the particular demands and requirements of a particular application.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Geology (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Environmental & Geological Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Treatment Of Sludge (AREA)
• Processing Of Solid Wastes (AREA)
• Disintegrating Or Milling (AREA)
• Separation Of Solids By Using Liquids Or Pneumatic Power (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

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Citations (4)

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• 2010
  • 2010-10-25 CA CA2821953A patent/CA2821953A1/en not_active Abandoned
  • 2010-10-25 BR BR112012009568A patent/BR112012009568A2/pt not_active IP Right Cessation
  • 2010-10-25 CN CN201080053216.4A patent/CN102811817B/zh not_active Expired - Fee Related
  • 2010-10-25 UA UAA201206180A patent/UA106092C2/ru unknown
  • 2010-10-25 KR KR1020127013321A patent/KR20130001208A/ko not_active Application Discontinuation
  • 2010-10-25 MX MX2012004754A patent/MX2012004754A/es active IP Right Grant
  • 2010-10-25 RU RU2012120810/03A patent/RU2569133C2/ru not_active IP Right Cessation
  • 2010-10-25 EP EP10825818.7A patent/EP2490817A4/en not_active Withdrawn
  • 2010-10-25 WO PCT/US2010/053992 patent/WO2011050370A1/en active Application Filing
  • 2010-10-25 JP JP2012535447A patent/JP5928955B2/ja not_active Expired - Fee Related
• 2012
  • 2012-05-22 ZA ZA2012/03723A patent/ZA201203723B/en unknown

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