Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/36—Regeneration of waste pickling liquors
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/02—Treatment of water, waste water, or sewage by heating
  • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
  • C02F1/048—Purification of waste water by evaporation
• • 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
• • 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

• the present invention relates to a method of separating a finegrained close-packed solid material from a liquid with which the fine-grained material is saturated.
• the fine-grained material in some cases may consist of metal compounds substantially without any value, e.g. certain pickling bath products which are harmless as far as the environment is concerned but where the liquid phase can be highly toxic or from other reasons harmful to the environment, in other cases the fine-grained material can be more valuable so that it is desired to take care of it.
• This concerns as well certain kinds of pickling bath deposits as certain metal oxides in the form of powder from venturi-filters in metallurgical plants.
• Another material which advantageously can be treated according to the invention is obtained at the machining of objects of high speed steel and other high grade alloys.
• Still another object also is to be able to separate the liquid from the liquid saturated mass in order to be able to re-use the liquid.
• the method of the invention is based upon the following principles:
• a sufficiently great gas pressure shall be established in the lower portions of the paste-like mass by heating the container from underneath in order that the gas will force the liquid upwards at a certain desired rate. This condition may be expressed
• the grain size, or more correctly the close-packing degree, shall be such that gas bubbles may not essentially proceed upwards and liquid drops not essentially fall downwards in the space between the grains (the particles). Agitation of the liquid in other words shall be prevented by the capillary forces in the fine divided mixture. It is herein presumed that a gas bubble having a tendency to proceed upwards is subjected to two forces in the critical moment when it shall be cut off, namely the net lift which is directed upwards and the surface tension which works as a downwards directed force. A liquid drop which is being cut and will fall downwards is influenced in an inversely way. If the channels between the particles in the mixture are smaller than the radius of the critical gas bubbles and the drops respectively, agitation of the liquid is consequently prevented.
• the close-packing degree thus should be such that the smallest breadth of the channels between the particels will not exceed the double critical radius r crit .
• Equation (3) therefore can be extended according to (4):
• Fig. 1 shows a container containing a liquid containing mass, from which the liquid phase is being separated from the solid phase.
• Fig. 2 shows a row of containers the liquid content of which is being separated.
• Fig. 3 illustrates a developed embodiment of the invention for continous liquid separation.
• Fig. 4 illustrates another developed embodiment of the invention and shows a container containing a liquid containing mass, where the liquid phase is being separated from the solid phase;
• Fig. 5 shows the pressure conditions in the container of the embodiment of the invention illustrated in Fig. 4 and in the embodiment illustrated in Fig. 1, respectively.
• a jelly mass of metal containing particles soaked in a liquid is generally shown as 1.
• the metal containing particles consist of metal oxides obtained from venturi filters from metallurgical furnaces or of metal compounds from pickling baths the particles normally have "microscopic" sizes in the order of 10 ⁇ m or smaller.
• the particles consist of grindings the majority of the grindings have sizes varying from very small, comparatively round particles having sizes in the order of about ⁇ 5 ⁇ m to somewhat larger, usually elongated particles having sizes of about 150 x 20 ⁇ m.
• This mixture of fine particles and liquid provides a mass 1 having a charac teristic jelly consistency.
• the mass 1 is collected in a container 2 which according to the embodiment consists of a conventional oil drum of the kind which is normally used as transport containers for the present "waste product".
• the container 2 is hermetically closed by a cover 3.
• a burner 4 is provided underneath the container for heating the content of the container 2.
• the burner is a gas burner which makes it possible in a practical way to take care of also combustible gases obtained at the process for the heating.
• other heating methods are conceivable, such as for example heating by means of an oil burner which has advantageously been used during performed experiments.
• electric heating principally is conceivable.
• Numeral 5 designates a conduit for the escape of combustible gas.
• a spillway is designated 6. Closing valves in the gas conduit and in the spillway 6 has been designated 7 and 8 respectively. Liquid which successively is collected on the surface of the mass has been designated 9.
• An oil drum containing 110 1 of a mass consisting of grindings of high speed steel soaked in cutting oil was heated from underneath by means of an oil burner.
• the oil content in the container at the start of the experiment was 32.5 weight percent. After 10 hours the oil content in the bottom portion of the vessel had decreased to less than 0.2%, i.e. this part of the container was practically free from oil.
• the centre of the mass essentially had been de-oiled while the outer portions at a level indicated in Fig. 1 had been decreased to 4.2 and 2.4 % respectively. In the upper part of the mass the oil content in the centre was 17.03. and in the outer portions 9.5 and 15% respectively.
• the sampling points have been indicated in Fig. 1. At the top there was an oil bed which was drained off through the spillway 6. At the end of the de-oiling there was formed a hot oil smoke which was led off through the conduit 5 and was burnt in a safety flame.
• a number of containers consisting of conventional oil drums were de-oiled in this way. Thereafter the containers with enclosures were melted in a 30 tons electric arc furnace in quantities up to 2 tons per charge. 1.5 tons per charge was shwon to be a suitable quantity corresponding to 5% of the total charge of raw materials. There were no tendencies to puffs, risks for accelerated lining wear or considerable development of smoke.
• the mass 1 consisted of sludge consisting of precipitated metal compounds. These very small particels substantially consisting of iron compounds.
• the liquid was an aqueous solution. This mass which contained about 45% water was heated in an oil drum according to the invention in the way illustrated in Fig. 1.
• the aqueous solution 9 which successively was collected on the upper surface was drained off, whereafter the essentially dried material could be dumped together with other waste material without casuing any harmful impact on the environment.
• FIG. 2 schematically shows a production plant for the carrying out of the method according to the embodiment of the invention illustrated in Fig. 1.
• the containers 1 are arranged on a common hearth 10 as is shown in the figure.
• the separated liquid is conveyed through a conduit 11 to a collecting vessel 12.
• Gas which is formed at the separation of liquid is utilized in the case it is combustible according to the embodiment for the heating in the hearth 10 and is for this purpose fed through a conduit 13.
• Fig. 3 shows a plant for continous treatment according to the invention.
• the raw material has the form of a sludge having a very high content of liquid, for example a sludge containing pickling bath deposits.
• a plant shown in Fig. 3 therefore is provided with a settling basin 21 with charging devices 22 for new raw material.
• the basin 21 has an inclined bottom so that sediment in the first place will collect in the deepest part of the basin.
• Suitable transport means may be provided for the transportation of sediment from other parts of the bottom of the basin. This has been schematically illustrated in Fig. 3 by a rake.
• the sludge in the basin 21 has been designated 24.
• a container in the form of a shaft 25 in which the settled liquid containing mass successively is collected.
• a heat-source 26 Beneath the shaft 25 there is provided a heat-source 26.
• this heat-source consists of a number of oil burners but it may also consist of gas burners, electrical heating means, means for the utilization of waste heat from other processes, or by combinations of the said kind of heatsources.
• a discharge device for the liquid phase has been designated 30.
• This device according to the embodiment. consists of a spillway. Also other discharge devices are conceivable, such as a suction device.
• a discharge channel for material having a high content of dry substance In the bottom portion of the shaft - the container 25 - there is provided a discharge channel for material having a high content of dry substance.
• conveyer means e.g. a worm conveyer 28, driven by a motor 29.
• the worm conveyor 28 also extends through the lower part of the shaft 25 so that the dry material in the bottom part of the shaft can be fed out through the channel 27.
• the channel 27 terminates in a reception chamber 31 which is subject to an overpressure. This has symbolically been indicated in Fig. 3 through compressor 32.
• a container for separated dry material has been designated 34.
• the equipment In order to increase the liquid separation capacity in the shaft 25 the equipment also may be provided with a filter press 33. In order further to increase the capacity it is also possible to subject the shaft 25 to a vacuum from above. This, however, requires a modified design of the plant, which is not illustrated in Fig. 3.
• the force in the upwards direction developed by the zone evaporation upon the liquid in the mass thus is adjusted such that it keeps pace with the supply of new liquid through the continous supply of new moist mass to the shaft 25 and to the discharge of dry material from the bottom part of the shaft.
• the bottom part of the shaft 25 at the same time is subjected to a certain over pressure which prevents steam or other gases from leaving the shaft through the discharge channel 27. It is recommended that the dry material is taken out from the chamber 31 through a feeding out valve in order that the process may be carried out entirely continous.
• the shaft 25 is provided with more than one discharge channels which can be run alternatingly so that the feeding out can be carried out without interruptions in the feeding.
• Fig. 4 and 5 there is illustrated another development of the method of the invention.
• the mass which shall be treated may be of the same kind as those which have been referred to with reference to Fig. 1 or consist of any other kind of material mentioned in the preamble of the specification.
• a container is shown as 42.
• the moist mass in the container 41 is shown as 43.
• the lower, drier portion which consequently substantially consists of comparatively dry powder has been designated 44.
• an evaporation zone 45 which is formed therein that the content of the container is heated from underneath by means of a number of burners 46.
• a conduit for the feeding off of the combustible gas from the container 41 is shown as 47.
• the conduit 47 is connected to an air pump 48 for establishing a vacuum in the container in the space 49 above the mass 43.
• a plunger 50 which can be pressed down against the mass 43 by means of a bar 51 which sealingly projects through the cover 42.
• the pressing of the plunger 50 against the mass 43 is done via a screen cloth 52 which can allow liquid from the mass 43 to pass through said screen cloth which is essentially impermeable for the solid particles in the mass 43.
• the liquid which is filtrated through the screen cloth 52 successively continous through openings 53 in the plunger 50 and is collected as a volume of liquid 54.
• the volume of liquid 54 is sucked up from the container 41 therein that the conduit 47 is replaced by a liquid suction conduit after the vacuum pump 48 has been taken away.
• the feeding off of the liquid can be performed under vacuum by an apparatus specially provided for liquid suction. It is also possible to remove the volume of liquid 54 as a final operation after terminated separation of the liquid from the solid phase in the container.
• Fig. 5 illustrates the conditions when about half the quantity of mass in the container has been treated.
• the pressure conditions in the container are schematically illustrated in the diagram in Fig. 5.
• the continous line in the diagram thus illustrates the conditions according to the developed embodiment of the invention, wherein a pressure difference ⁇ P 2 exists between the pressure in the "dry" part 44 of the mass in the container and the gas pressure on the surface of the mass.
• the dashed line in the diagram in Fig. 5 illustrates the corresponding conditions in the case when the pressure in the space 49 in the upper portion of the container 41 corresponds to atmospheric pressure and the plunger 50 is not pressed against the mass 43.
• the pressure difference ⁇ P 1 which is obtained in this case is essentially lower than the pressure difference ⁇ P 2 .
• the process according to the embodiment may also be combined with continous supply of new mass to the upper part of the container and with continous feeding away of separated liquid and dried material, the level of the evaporation zone being kept essentially constant in the space.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Environmental & Geological Engineering (AREA)
• Metallurgy (AREA)
• Life Sciences & Earth Sciences (AREA)
• Mechanical Engineering (AREA)
• Geology (AREA)
• Manufacturing & Machinery (AREA)
• Geochemistry & Mineralogy (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Hydrology & Water Resources (AREA)
• Water Supply & Treatment (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

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Citations (4)

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• 1978
  • 1978-08-10 GB GB7934463A patent/GB2036276B/en not_active Expired
  • 1978-08-10 DE DE782857026T patent/DE2857026T1/de active Granted
  • 1978-08-10 WO PCT/SE1978/000029 patent/WO1979000137A1/en unknown
  • 1978-08-28 AT AT623578A patent/AT361881B/de active
  • 1978-09-08 JP JP11055778A patent/JPS5449976A/ja active Pending
  • 1978-09-08 IT IT2747578A patent/IT1099465B/it active
  • 1978-09-08 FR FR7825883A patent/FR2402467B1/fr not_active Expired

Patent Citations (4)

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