Source: http://patents.com/us-9701553.html
Timestamp: 2018-02-18 22:04:53
Document Index: 137462512

Matched Legal Cases: ['Application No. 201204199', 'application No. 2011', 'application No. 201210188712', 'Application No. 12178817', 'Application No. 2011', 'Application No. 2011', 'Application No. 201210143355', 'Application No. 201110259626', 'Application No. 201203420', 'Application No. 2011']

US Patent # 9,701,553. Copper recovery apparatus - Patents.com
United States Patent 9,701,553
Fukaya , et al. July 11, 2017
Fukaya; Taro (Higashikurume, JP), Tsutsumi; Kenji (Yokohama, JP), Yamazaki; Atsushi (Tokyo, JP), Yamanashi; Ichiro (Tokyo, JP), Noguchi; Hirofumi (Sakai, JP), Kikuchi; Yasutaka (Tokyo, JP), Seki; Shuji (Yokohama, JP)
Family ID: 1000002697902
14/297,227
US 20140284256 A1 Sep 25, 2014
13491399 Jun 7, 2012 8986541
Jun 8, 2011 [JP] 2011-128632
Current CPC Class: C02F 1/5281 (20130101); C02F 1/001 (20130101); C02F 1/488 (20130101); C02F 1/5245 (20130101); C02F 2101/20 (20130101); C02F 2201/48 (20130101); C02F 2209/06 (20130101); Y10S 210/912 (20130101)
Current International Class: C02F 1/00 (20060101); C02F 1/48 (20060101); C02F 1/52 (20060101); C02F 1/20 (20060101)
4299541 November 1981 Ohara et al.
5900146 May 1999 Ballard et al.
7739745 June 2010 Ishimatsu et al.
8221622 July 2012 Fukaya et al.
8354022 January 2013 Fukaya et al.
8512570 August 2013 Fukaya et al.
8540883 September 2013 Fukaya et al.
2001/0042688 November 2001 Nabekura et al.
2005/0009002 January 2005 Chen
2005/0258103 November 2005 Cort
2006/0146604 July 2006 Muraki et al.
2006/0194535 August 2006 Houldsworth et al.
2007/0009232 January 2007 Muraki et al.
2008/0288136 November 2008 Itatsu
2009/0277843 November 2009 Fukaya et al.
2010/0326898 December 2010 Scholz et al.
2012/0234767 September 2012 Fukaya
2012/0234768 September 2012 Fukaya et al.
2012/0238003 September 2012 Fukaya
2012/0288435 November 2012 Fukaya
2012/0312727 December 2012 Fukaya et al.
2013/0055407 February 2013 Hirayama et al.
1375507 Oct 2002 CN
1748832 Mar 2006 CN
101229504 Jul 2008 CN
201587966 Sep 2010 CN
1 189 432 Mar 2002 EP
52-129063 Oct 1977 JP
55-029012 Mar 1980 JP
H01-107890 Apr 1989 JP
06-114382 Apr 1994 JP
H07-047371 Feb 1995 JP
09-327611 Dec 1997 JP
H10-085761 Apr 1998 JP
2000-167569 Jun 2000 JP
2002-239559 Aug 2002 JP
2003-235001 Aug 2003 JP
2003-346000 Dec 2003 JP
2004-097952 Apr 2004 JP
2004-249251 Sep 2004 JP
2005-252435 Sep 2005 JP
2005-254158 Sep 2005 JP
2005-296837 Oct 2005 JP
2005-324137 Nov 2005 JP
2006-108961 Apr 2006 JP
2006-159042 Jun 2006 JP
2007-083179 Apr 2007 JP
2007-275757 Oct 2007 JP
2009-268976 Nov 2009 JP
2010-069363 Apr 2010 JP
2010-207680 Apr 2010 JP
2010-110688 May 2010 JP
2010-137147 Jun 2010 JP
2010-207755 Sep 2010 JP
2011-046787 Mar 2011 JP
2012-187083 Oct 2012 JP
Search Report mailed by Singapore Patent Office on Apr. 11, 2013 in Singapore Patent Application No. 201204199-2 in 15 pages. cited by applicant .
First Office Action mailed by Japan Patent Office on May 14, 2013 in Japanese patent application No. 2011-128632. cited by applicant .
Notification of the First Office Action issued by State Intellectual Property Office (SIPO) of the People's Republic of China on Aug. 5, 2013 in the corresponding Chinese patent application No. 201210188712.1. cited by applicant .
Toshiba, Background Art Information, Undated. cited by applicant .
Background Art Information issued by Toshiba on Jun. 8, 2012--1 page. cited by applicant .
Background Art Information issued by Toshiba in U.S. Appl. No. 13/194,115--2 pages. cited by applicant .
European Search Report Dated Jun. 24, 2013 in the corresponding European Patent Application No. 12178817.8 for U.S. Appl. No. 13/609,648--8 pages. cited by applicant .
First Office Action mailed Oct. 16, 2012 in the corresponding Japanese Patent Application 2012-010319 --9 pages. cited by applicant .
First Office Action mailed by Japan Patent Office on Apr. 2, 2013 corresponding to Japanese Patent Application No. 2011-105209 in 6 pages. cited by applicant .
First Office Action mailed by Japan Patent Office on Jan. 6, 2015 in the corresponding Japanese Application No. 2011-198711 for U.S. Appl. No. 13/194,115--7 pages. cited by applicant .
Notification of the First Office Action issued by State Intellectual Property Office (SIPO) of the People's Republic of China on Aug. 30, 2013 in the corresponding Chinese Patent Application No. 201210143355.7--19 pages. cited by applicant .
Notification of the First Office Action mailed by Intellectual Property Agency, People's Republic of China on Office Action Jan. 6, 2014 in Chinese Application No. 201110259626.0--18 pages. cited by applicant .
"Protected User Mode Audio (PUMA)", Nov. 10, 2011 http://web.archive.org/web/20111110135613/http://msdn.microsoft.com/en-us- /library/windows/desktop.dd756608%28v=US.85%29.as.px[retrievedon Jun. 12, 2013]. cited by applicant .
Search Report and Written Opinion issued by Hungarian Intellectual Property Office on Jul. 4, 2013 in the corresponding Hungarian Patent Application No. 201203420-3 for U.S. Appl. No. 13/467,826--15 pages. cited by applicant .
Sing et al. "Removal of Fluoride from Spent Pot Linger Leachate Using Ion Exchange," Water Environment Research, vol. 71, No. 1, pp. 36-42. cited by applicant .
Xu Jinlan et al., "Lime precipitation-coagulation precipitation treating fluoride-containing wastewater test," Technology of Water Treatment, vol. 29, No. 5, pp. 282-285. cited by applicant.
This application is a divisional of U.S. patent application Ser. No. 13/491,399 filed on Jun. 7, 2012, which issued as U.S. Pat. No. 8,986,541 and which is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2011-128632, filed Jun. 8, 2011, the entire contents of each of which are incorporated herein by reference.
1. A copper recovery apparatus comprising: a mixing and precipitation tank configured to receive water comprising copper ions, an alkali and a filter aid comprising magnetic particles having an average particle diameter of 0.5 to 20 .mu.m to prepare an alkaline suspension containing a precipitate of copper compound; a heater configured to heat the suspension in the mixing and precipitation tank to convert at least a part of the copper compound in the suspension into copper oxide; a filter-aid feeder configured to supply the filter aid to the mixing and precipitation tank; a solid-liquid separator comprising a filter, the solid-liquid separator being configured to receive the suspension from the mixing and precipitation tank to subject the suspension to a filtration by the filter so that the precipitate and the filter aid which is retained on the filter is separated from a filtrate; a cleaning-water supply line configured to supply water to the filter having the precipitate and the filter aid retained thereon to remove the precipitate and the filter aid from the filter; a cleaning-water discharge line configured to discharge from the solid-liquid separator the precipitate and the filter aid together with the water supplied by the cleaning water supply line to the filter; a separation tank configured to receive the precipitate, the filter aid and the water discharged from the solid-liquid separator and separate the filter aid from the precipitate and the water by utilizing a magnetic field; and a filter-aid return line configured to return the filter aid separated in the separation tank to the filter-aid feeder.
2. The copper recovery apparatus of claim 1, wherein the filter aid comprises an aggregate which is obtainable by aggregating magnetic particles of which each surface is coated with a polymer; the magnetic particles have an average particle diameter D1 which is within a range of 0.5 to 20 .mu.m; the aggregate has an average aggregate diameter D2 which together with D1 satisfies the relationship: D1<D2.ltoreq.20 .mu.m; and the polymer has an average coating thickness t ranging 0.01.ltoreq.t.ltoreq.0.25 .mu.m.
7. The copper recovery apparatus of claim 1, further comprising: an alkali feeder configured to add the alkali to the mixing and precipitation tank; a pH meter configured to measure a pH value of the treated water in the mixing and precipitation tank; and an alkali-feed controller configured to control the amount of the alkali added from the alkali feeder to the mixing and precipitation tank so that the pH value of the treated water in the mixing and precipitation tank is neutral, based on the pH value measured by the pH meter.
In general, according to one embodiment, a copper recovery apparatus includes a precipitation tank, a mixing tank, a filter-aid feeder, a solid-liquid separator comprising a filter, a cleaning-water supply line, a cleaning-water discharge line, a separation tank, and a filter-aid return line. The precipitation tank is configured to receive copper ions-containing water to be treated and add an alkali to the water to be treated to prepare treated water containing a precipitate of copper compound. The mixing tank configured to mix a filter aid containing magnetic particles having an average particle diameter of 0.5 to 20 .mu.m with a dispersion medium to prepare a suspension. The filter-aid feeder configured to supply the filter aid to the mixing tank. The solid-liquid separator is configured to receive the suspension from the mixing tank so that a precoat layer of the filter aid is deposited on the filter, and then, receive the treated water from the precipitation tank so as to allow the treated water to be passed through the filter on which the precoat layer is deposited to separate the precipitate retained on the precoat layer from a filtrate. The cleaning-water supply line is configured to supply water to the filter on which the precoat layer having the precipitate retained thereon is deposited and to remove the precipitate and the filter aid from the filter. The cleaning-water discharge line is configured to discharge from the solid-liquid separator the precipitate and the filter aid together with the water supplied by the cleaning water supply line to the filter. The separation tank is configured to receive the precipitate, the filter aid and the water discharged from the solid-liquid separator and separate the filter aid from the precipitate and the water by utilizing a magnetic field. The filter-aid return line is configured to return the filter aid separated in the separation tank to the filter-aid feeder.
(1) A copper recovery apparatus according to the present embodiment comprises: a precipitation tank 2 configured to add an alkali to copper ions-containing water to be treated and to precipitate a precipitate containing a copper compound; a heating mechanism 22 configured to heat the precipitate in the precipitation tank to form at least a part of the copper compound in the precipitate into copper oxide; a filter aid feeder 5 which supplies a filter aid of which an average diameter of particles or aggregates containing a magnetic substance is 0.5 to 20 .mu.m; a mixing tank 6 configured to mix the filter aid with a dispersion medium to prepare a suspension; a solid-liquid separator 3 comprising a filter 33 which filtrates the filter aid from the suspension upon supply of the suspension from the mixing tank to form a precoat layer comprising the filter aid and filtrates the copper compound containing the copper oxide from the treated water upon supply of the treated water from the precipitation tank so that the copper compound is captured by the precoat layer; a treated water supply line L2 configured to supply the treated water to the solid-liquid separator from the precipitation tank; a mixing line L7 connected to the treated water supply line, which is configured to mix the suspension from the mixing tank with the treated water from the treated water supply line; a cleaning line L11 configured to supply cleaning water to the filter so that the precoat layer is cleaned from the filter; a separation tank 4 which separates the copper compound from the filter aid, the copper compound and the filter aid being contained in cleaning effluent discharged together with the cleaning water from the solid-liquid separator; a cleaning effluent line L32 which sends the cleaning effluent from the solid-liquid separator to the separation tank; and a filter aid return line L5 which returns the filter aid separated in the separation tank to the filter-aid feeder (FIG. 1).
The present embodiment comprises: precipitating copper oxide as the copper compound by alkalizing the water to be treated in the precipitation tank; mixing with the dispersion medium the filter aid of which the average diameter of the particles or the aggregates containing the magnetic substance is 0.5 to 20 .mu.m; supplying the mixture from the mixing tank to the solid-liquid separator via the treated water supply line to form a deposit layer of the filter aid on the filter; supplying the treated water from the precipitation tank to the solid-liquid separator via the treated water supply line so that the copper oxide is captured when the treated water is passed through the filter aid layer; supplying the cleaning water to the solid-liquid separator device via the cleaning line to clean the copper oxide together with the filter aid from the filter; supplying the cleaning effluent from the solid-liquid separator to the separation tank via the cleaning effluent line; and separating and recovering the copper oxide from the filter aid which is cleaned in the separation tank and returning the separated and recovered filter aid from the separation tank to the filter feeder via the filter aid return line while recovering the separated and recovered copper oxide. Thereby, the present embodiment enables to reuse the separated and recovered filter aid in the filter aid feeder and attaining high recovery efficiency by directly separating the precipitated copper particles having a very small particle diameter (FIG. 1). As used herein, "copper oxide" includes a double salt and a mixed salt each containing copper oxide. Examples of such copper oxide include a combination of copper carbonate and copper oxide, a combination of copper sulfate and copper oxide, and the like.
(2) The copper recovery apparatus according to the present embodiment comprises: a mixing and precipitation tank 2A which prepares a suspension by mixing a filter aid of which an average diameter of particles or aggregates containing a magnetic substance is 0.5 to 20 .mu.m with water to be treated and alkalizing water to be treated so that a copper compound is precipitated; a heating mechanism 22 which heats the copper compound in the mixing an precipitation tank to form at least a part of the copper compound into copper oxide; a filter aid feeder 5 which supplies the filter aid to the mixing and precipitation tank; a solid-liquid separator 3 comprising a filter 33 which filtrates the precipitated copper compound and the filter aid from the suspension upon supply of the suspension from the mixing and precipitating tank to form a deposit layer comprising the precipitated copper compound containing the copper oxide and the filter aid; a treated water supply line L2 which supplies the treated water from the mixing and precipitation tank to the solid-liquid separator; a cleaning line L11 which supplies cleaning water to the filter so that the deposit layer is cleaned from the filter; a separation tank 4 which separates the precipitated copper compound from the filter aid, the copper compound and the filter aid being contained in cleaning effluent discharged together with the cleaning water from the solid-liquid separator; a cleaning effluent line L32 which sends the cleaning effluent from the solid-liquid separator to the separation tank; and a filter aid return line L5 which returns the filter aid separated in the separation tank to the filter aid feeder (FIG. 4).
(3) Preferably, in the apparatus of (1) or (2): the filter aid comprises an aggregate obtainable by aggregating magnetic particles having surface coated with a polymer; an average particle diameter D1 of the magnetic particles is within a range of 0.5 to 20 .mu.m; the average particle diameter D1 of the magnetic particle and an average aggregate diameter D2 of the aggregates satisfy the following relationship: D1<D2.ltoreq.20 .mu.m; and an average coating thickness t of the polymer ranges 0.01.ltoreq.t.ltoreq.0.25 .mu.m (FIG. 3).
In the present embodiment, the average particle diameter D1 of the magnetic particles may preferably be within the range of 0.5 to 20 .mu.m, and a more preferred range of the diameter D1 is 0.5 to 15 .mu.m. When the average particle diameter D1 of the magnetic particles is less than 0.5 .mu.m, the particles are densely aggregated to make a distance between particles too small, thereby making it difficult to attain an effective treated water passing rate. On the other hand, when the average particle diameter D1 exceeds 20 .mu.m, the particles are coarsely aggregated to make the distance between particles too long and to allow fine precipitates in water to readily pass therethrough, thereby largely deteriorating efficiency of recovering the precipitated copper compound. When the average particle diameter D1 is less than 15 .mu.m, the recovery efficiency of the copper compound particles is further improved. By the way, the inventors found that it is difficult to attain the effective copper recovery efficiency in the case where the average particle diameter D1 of the magnetic particles is 26 .mu.m, for example. Such findings suggest that the copper recovery efficiency is deteriorated when the average particle diameter D1 of the magnetic particles is excessively large.
In the present embodiment, the average particle diameter D1 and the average aggregate diameter D2 of the aggregates of the magnetic particles may preferably satisfy the following relationship: D1<D2.ltoreq.20 .mu.m, more preferably D1<D2.ltoreq.15 .mu.m. When the average aggregate diameter D2 of the aggregates exceeds 20 .mu.m, the fine precipitates in water are allowed to readily pass through as described above, thereby largely deteriorating the copper recovery efficiency. When the average particle diameter D2 is 15 .mu.m, the copper recovery efficiency is further improved as described above.
In the present embodiment, the average coating thickness t of the polymer may preferably range 0.01.ltoreq.t.ltoreq.0.25 .mu.m, more preferably 0.01.ltoreq.t.ltoreq.0.15 .mu.m. When the average coating thickness t of the polymer is less than 0.01 .mu.m, the desired coating effect is not attained, and the aggregate is deteriorated in strength to be unusable. On the other hand, when the coating thickness t exceeds 0.25 .mu.m, clearances between the magnetic particles in the aggregate are filled with a resin to reduce not only the water passing rate of the treated water but also roughness, and, therefore, a copper compound particle capture rate tends to be lowered. Further, when the coating thickness t is 0.15 .mu.m or less, appropriate roughness is attained to enhance capture performance of capturing the copper compound particles and to increase the treated water passing rate, thereby further improving the copper recovery efficiency.
(4) The copper recovery apparatus according to the present embodiment comprises: a precipitation tank 2B which receives copper ions-containing water to be treated, an alkali feeder which adds an alkali to the water to be treated contained in the precipitation tank to precipitate a copper compound; a filter aid feeder 5 which supplies a filter aid of which an average particle diameter of particles or aggregates containing a magnetic substance is 0.5 to 20 .mu.m; a mixing tank 6 which mixes the filter aid supplied from the filter aid feeder with a dispersion medium to prepare a suspension; a solid-liquid separator 3 comprising a filter 33 which filtrates the filter aid from the suspension upon supply of the suspension from the mixing tank to form a precoat layer formed of the filter aid and filtrates the copper compound containing the copper oxide from the treated water so that the copper compound is captured by the precoat layer; a treated water supply line L2 which supplies the treated water from the precipitation tank to the solid-liquid separator; a mixing line L7 which is connected to the treated water supply line to mix the suspension from the mixing tank with the treated water of the treated water supply line; a cleaning line L11 which supplies the filter with cleaning water in order to clean the precoat layer from the filter; a separation tank 4 which separates the copper compound from the filter aid, the copper compound and the filter aid being contained in cleaning effluent discharged together with the cleaning water from the solid-liquid separator; a cleaning effluent line L32 which sends the cleaning effluent from the solid-liquid separator to the separation tank; a filter aid return line L5 which returns the filter aid which is separated in the separation tank to the filter aid feeder; a unit 23 which measures a pH value of the treated water in the precipitation tank; a pH control mechanism 24 which stops the addition of the alkali from the alkali feeder based on the detected pH value measured by the pH measurement unit to stop a reaction when the pH value of the treated water in the precipitation tank is within the neutral range or adjusts the alkali addition from the alkali feeder based on the detected pH value measured by the pH measurement unit, so as to allow the reaction to continuously proceed in a state where the pH value of the treated water in the precipitation tank is maintained within the neutral range (FIG. 6).
In the present embodiment, in the pH control mechanism 24, the addition of alkali to the treated water is stopped based on the detected pH value to stop the reaction when the pH value of the treated water in the precipitation tank is within the neutral range, or the addition of alkali to the treated water is adjusted based on the detected pH value, so as to allow the reaction to continuously proceed in the state where the pH value of the treated water in the precipitation tank is maintained within the neutral range. Therefore, the pH value of the treated water is maintained within the neutral range to allow the copper oxide generation reaction to proceed well as compared to the copper hydroxide generation reaction, thereby attaining the precipitation of a large amount of copper oxide particles. As used herein, the "neutral range" substantially means a range of pH 5 to 9.
(5) The copper recovery apparatus of the present embodiment comprises: a mixing and precipitation tank 2A which mixes a filter aid of which an average diameter of particles or aggregates containing a magnetic substance is 0.5 to 20 .mu.m with water to be treated and alkalizes the treated water to precipitate a copper compound so as to prepare a suspension; a heating mechanism 22 which heat the copper compound in the mixing and precipitation tank to convert at least a part of the copper compound into copper oxide; a filter aid feeder 5 which supplies the filter aid to the mixing and precipitation tank; a solid-liquid separator 3 comprising a filter 33 which filtrates the precipitated copper compound and the filter aid from the suspension upon supply of the suspension from the mixing and precipitating tank to form a deposit layer comprising the precipitated copper compound containing the copper oxide and the filter aid; a treated water supply line L2 which supplies the treated water from the mixing and precipitation tank to the solid-liquid separator; a cleaning line L11 which supplies cleaning water to the filter so that the deposit layer is cleaned from the filter; a separation tank 4 which separates the precipitated copper compound from the filter aid, the copper compound and the filter aid being contained in cleaning effluent discharged together with the cleaning water from the solid-liquid separator; a cleaning effluent line L32 which sends the cleaning effluent from the solid-liquid separator to the separation tank; a filter aid return line L5 which returns the filter aid separated in the separation tank to the filter-aid feeder; a unit 23 which measures a pH value of the treated water in the precipitation tank; and a pH control mechanism 24 which stops the addition of the alkali from the alkali feeder based on the detected pH value measured by the pH measurement unit to stop a reaction so that the pH value of the treated water in the precipitation tank is within the neutral range or adjusts the alkali addition from the alkali feeder based on the detected pH value measured by the pH measurement unit, so as to allow the reaction to continuously proceed in a state where the pH value of the treated water in the precipitation tank is maintained within the neutral range.
(6) Preferably, in the apparatus of (4) or (5): the filter aid comprises an aggregate obtainable by aggregating magnetic particles of which each of surfaces is coated with a polymer; an average particle diameter D1 of the magnetic particles is within a range of 0.5 to 20 .mu.m; the average particle diameter D1 of the magnetic particles and an average aggregate diameter D2 of the aggregates satisfies the following relationship: D1<D2.ltoreq.20 .mu.m; and an average coating thickness t of the polymer ranges 0.01.ltoreq.t.ltoreq.0.25 .mu.m (FIG. 3). In the present embodiment, the effects same as those of (3) are attained.
In the embodiments or examples described below, copper oxide is precipitated by directly adding an alkali solution to water be treated containing copper ions such as a copper sulfate solution. As the type of the alkali, sodium hydroxide is most suitably used without particular limitation thereto. The direct addition of alkali solution causes a particle diameter of precipitated copper particles to be reduced, thereby making it quite difficult to separate the copper particles from water. However, since the method of any one of the embodiments described below enables to efficiently separate the fine copper compound particles (average particle diameter: 0.01 to 10 .mu.m), the number of process steps is reduced, and the apparatus is readily simplified.
Further, the precipitation tank 2 has a drum heater 22. Power supply to the drum heater 22 is controlled by a controller (not shown), so that a temperature of the precipitation tank 2 is controlled to 60.degree. C. The drum heater 22 is used for heating the treated water to change copper hydroxide of the copper compounds contained in the treated water into copper oxide by oxidization.
The solid-liquid separator 3 incorporates a filter 33 which partitions an internal space of the separator 3 into an upper introduction space 31 and a lower discharge space 32. As the filter 33, those obtained by weaving a polymer fiber such as polyester, nylon, polypropylene, a fluorine fiber, and cellulose acetate by plain weaving, twilling, double weaving, or the like are usable. A filter thickness is substantially 1 mm or less, and a filter mesh size is substantially about 1 to 20 .mu.m.
In the precipitation tank 2, sodium hydroxide as the alkali is added to the copper-containing water to be treated to precipitate a copper compound containing copper hydroxide as a main component. The precipitated copper compound is heated to lead the oxidization of a part of the copper hydroxide, resulting in the formation of copper oxide. A reaction temperature and a reaction period may be those which cause at least a part of the copper hydroxide to change into copper oxide and may preferably be within the ranges of 60.degree. C. to 80.degree. C. and 1 to 30 minutes. As a heating unit, a resistance heating element such as the drum heater 22 or the like provided on an outer periphery of the precipitation tank 2 may be used. The heating of the treated water may be performed while adding the alkali agent or may be performed by supplying the treated water through a piping of which a temperature is adjusted, such as a heat exchanger.
The filter aid to be used contains magnetic particles, and the magnetic particles have an average particle diameter within the range of 0.5 to 20 .mu.m. The filter aid may be particles of a magnetic substance or may be the magnetic particles 11 of which each of surfaces is coated with a coating agent 12 such as a polymer as shown in FIG. 3A. Alternatively, the filter aid may be aggregates 13 in each of which the magnetic particles 11 each coated with a polymer are aggregated as shown in FIG. 3B.
More preferably: the average particle diameter D1 of the magnetic substance of the filter aid is 0.5 to 20 .mu.m; a part of the magnetic substance is aggregated by a polymer or trialkoxysilane; an average aggregate diameter D2 thereof, with the D1, satisfies the relationship D1<D2.ltoreq.20 .mu.m; and a surface coating thickness t of the polymer is within the range of 0.01.ltoreq.t.ltoreq.0.25 .mu.m. As used herein, "average particle diameter" means the one measured by laser diffraction. More specifically, the average particle diameter is measured by using SALD-DS21 Type Measurement Apparatus (trade name) manufactured by Shimadzu Corporation, for example. When the average particle diameter of the magnetic substance as primary particles exceeds 20 .mu.m, a distance between the particles can be long to allow fine precipitates in water described later in this specification to readily pass through. On the other hand, when the primary particle diameter is less than 0.5 .mu.m, the particles are densely aggregated to make it difficult to attain the effective treated water passing rate though fine precipitates in water are removed.
For example, ferromagnetic substances in general are usable as the magnetic substance, and examples thereof include iron, an alloy containing iron, magnetite, ilmenite, pyrrhotite, magnesia ferrite, cobalt ferrite, nickel ferrite, balium ferrite, and the like. Among these, the ferrite compound which is excellent in stability in water is more effective. For example, magnetite (Fe.sub.3O.sub.4) is not only inexpensive, but also is stable as a magnetic substance in water and safe as an element. Therefore, magnetite is preferred since it is readily used for water treatments. Further, the magnetic substance may be in various shapes such as a spherical shape, a polyhedral shape, and the like, or be in amorphous, and are not particularly limited. The preferred particle diameter and shape of the magnetic substance which is suitably used may appropriately be selected in view of a production cost and the like, and the spherical shape or a polyhedral structure of which corners are rounded is preferred. The magnetic substance may be plated by an ordinary plating process such as Cu plating and Ni plating as required.
In the present embodiment, a material suitably used as the polymer which coats the surfaces of the magnetic particles and aggregates the particles may be selected depending on the purpose. Preferably, polyacrylonitrile, polymethylmethacrylate and polystyrene which are easily coated on the magnetic substance and has acid/alkali resistance, copolymers thereof, a phenol resin excellent in dispersion in water, or a trialkoxysilane condensate which has high stability in water by firmly adhering to the magnetic substance may be used. The polymer may preferably be coated in such a manner that the average surface coating thickness t of the polymer is 0.01.ltoreq.t.ltoreq.0.25 .mu.m. When the coating thickness t is less than 0.01 .mu.m, strength of a secondary aggregate is reduced to make the use in water difficult in some cases. When the coating thickness t is more than 0.25 .mu.m, clearances between particles are narrowed to make it difficult to ensure the effective water passing rate when used as the filter aid in some cases. Calculation of a polymer coating amount may be carried out by observation using an optical microscope or scanning electron microscope (SEM), while the average thickness of the polymer layer is accurately obtained by heating the filter aid under an oxygen-free situation to lead the thermal decomposition thereof, and then detecting an amount of weight loss, i.e. a polymer coating amount, and calculating the polymer layer average thickness from specific surface areas of the particles.
In the case where the magnetic substance comprises the aggregate in which each of the particles each coated with the polymer are aggregated, the aggregate may preferably have a characteristic shape. More specifically, in the filter aid of the present embodiment, the average aggregate diameter D2 of the aggregates satisfies the relationship D1<D2.ltoreq.20 .mu.m when the average particle diameter of the magnetic substance is D1. When the aggregates have such a size, the particles are not aggregated in the form of a sphere but are in the form of a baroque shape. Owing to the baroque shape, appropriate clearances are guaranteed during the filtering and deposition when the aggregate is used as the filter aid or a precoat material, thereby attaining a filtering flow rate while entrapping the copper compound in the treated water. When the average aggregate diameter D2 of the aggregates 13 is too large, i.e. exceeds 20 .mu.m, clearance between the aggregates is increased to sometimes make it difficult to entrap the copper precipitate in water. Further, the average aggregate diameter may more preferably be such that D1<D2.ltoreq.15 .mu.m. When the average aggregate diameter D2 is 15 .mu.m or less, the copper precipitate in water is more efficiently entrapped.
A copper recovery apparatus 1A of the present embodiment is used for body-feed filtration, which, particularly, is effectively used in the case where a copper compound concentration in water is high. The feature by which the copper recovery apparatus 1A of the present embodiment is different from the apparatus 1 of the first embodiment is that the apparatus 1A is not provided with any mixing tank 6, and a mixing and precipitation tank 2A is provided in place of the precipitation tank 2 of the first embodiment. The mixing and precipitation tank 2A has both of a precipitation function of adding an alkali to water to be treated and precipitating a copper compound and a mixing function of adding a filter aid to the treated water and mixing the filter aid with the treated water. More specifically, in the copper recovery apparatus 1A of the present embodiment, the filter aid is directly supplied from a filter aid tank 5 to the mixing and precipitation tank 2A via a direct supply line L6' without flowing through the mixing tank described in the foregoing.
In the second copper recovery method, the water containing copper to be treated is added to the precipitation tank in advance of adding alkali, and the alkali is added to cause the reaction to proceed. Here, a pH value in the tank is monitored and the addition of alkali is stopped so that the pH obtained is within the neutral range, resulting in generating copper oxide. It is believed that the copper oxide generation reaction proceeds according to the following formulas (1) and (2), and the copper hydroxide generation reaction proceeds according to the following formulas (3) and (4). The following formulas are examples in which copper oxide is precipitated by using hydrogen peroxide as an oxidizer, copper sulfate is precipitated as a copper component, and sulfuric acid is used as an acid component. The reaction formulas (1) and (2) indicate the copper oxide generation reaction (hereinafter referred to as Reaction 1) and the reaction formulas (3) and (4) indicate copper hydroxide generation reaction (hereinafter referred to as Reaction 2). Cu.sub.2+H.sub.2O.sub.2.fwdarw.CuO (precipitated)+H.sub.2O (1) CuO+H.sub.2SO.sub.4.fwdarw.CuSO.sub.4 (dissolved)+H.sub.2O (only in acid-environment) (2) Cu.sup.2++2NaOH.fwdarw.Cu(OH).sub.2 (precipitated)+2Na.sup.+ (3) CuO+H.sub.2SO.sub.4.fwdarw.H.sub.2So.sub.4 (dissolved)+2H.sub.2O (only in acid-environment) (4)
(Filter Aid A) Magnetite particles (average particle diameter: 2 .mu.m)
(Filter Aid B) Magnetite particles (average particle diameter: 0.5 .mu.m)
(Filter Aid C) Magnetite particles (average particle diameter: 5 .mu.m)
A solution was obtained by dissolving 30 parts by weight of polymethylmethacrylate into 3 L of tetrahydrofuran, and 300 parts by weight of magnetite particles having an average particle diameter of 2 .mu.m (A) was dispersed into the solution to obtain a composition. The composition was sprayed slowly by using a mini spray dryer (B-290 manufactured by Shibata Scientific Technology Ltd.) to prepare the filter aid having an average secondary particle diameter of about 11 .mu.m (B), which was aggregated in the form of a sphere. An average coating thickness was 0.038 .mu.m (C).
A solution was obtained by dissolving 30 parts by weight of polymethylmethacrylate into 3 L of tetrahydrofuran, and 300 parts by weight of magnetite particles having an average particle diameter of 2 .mu.m (A) was dispersed into the solution to obtain a composition. The composition was sprayed slowly by using a mini spray dryer (B-290 manufactured by Shibata Scientific Technology Ltd.) to prepare the filter aid having an average secondary particle diameter of about 18 .mu.m (B), which was aggregated in the form of a sphere. An average coating thickness was 0.038 .mu.m (C).
A solution was obtained by dissolving 40 parts by weight of a resole type phenol resin into 3 L of water, and 300 parts by weight of magnetite particles (specific surface area: 2.5 m.sup.2/g) having an average particle diameter of 2 .mu.m (A) was dispersed into the solution to obtain a composition. The composition was sprayed slowly by using a mini spray dryer (B-290 manufactured by Shibata Scientific Technology Ltd.) to prepare the filter aid having an average secondary particle diameter of about 11 .mu.m (B), which was aggregated in the form of a sphere. An average coating thickness calculated from the density of a polyphenol resin and the specific surface area of magnetite was 0.044 .mu.m (C).
In Example 1, the apparatus 1 of the first embodiment shown in FIG. 1 was used. As water to be treated, a copper sulfate solution containing 50 mg/L of copper was provided. The water to be treated was supplied to the precipitation tank 2, and 48% sodium hydroxide was added thereto by dropping to adjust a pH value of the treated water to pH 10. After mixing for a certain period of time, precipitation of light blue copper hydroxide was confirmed. The drum heater 22 was fed with electricity to raise a water temperature to 60.degree. C., and mixing was performed at the temperature. After that, generation of copper oxide was confirmed since there was a blackened part. Further, a filter aid was supplied from the filter aid tank 5 charged with Filter Aid A to the mixing tank 6 and mixed with water so as to prepare a filter aid slurry. The filter aid slurry was supplied to the solid-liquid separator 3 to prepare a filter aid layer having an average thickness of 1 mm on the filter. After that, the treated water was supplied from the precipitation tank 2 to the solid-liquid separator 3 to perform filtering. Then, it was confirmed from the filtrated water that 99% or more of copper contained in the treated water was recovered. After the filtering, tap water was supplied from the upper line L10 of the solid-liquid separator 3 to remove ion components attached to the copper compound contained in the cake. Subsequently, cleaning water was supplied from a lateral direction of the filter 33 to disintegrate the layer formed on the filter, and the pieces were supplied to the separation tank 4. The stirrer 41 in the separation tank was operated to separate the filter aid from the copper compound, and the electromagnet 42 was operated to capture only the filter aid, followed by discharging discharged water. The discharged water was analyzed to confirm that main components of the slurry were copper hydroxide and copper oxide. After that, a magnetic field of the magnet was released, and cleaning water was supplied to obtain a filter aid slurry. Then, the filter aid slurry was returned to the filter aid tank 5. After that, the same operation as described above was conducted by supplying the filter aid slurry to mixing tank 6, and reuse thereof was achieved without any problem.
In Comparative Example 1, the apparatus same as that used in Example 1 was used, and an experiment was conducted in the same manner as in Example 1 except for using magnetite particles having an average particle diameter of 0.3 .mu.m in place of Filter Aid A. Filtering was conducted, but the filter was clogged to fail to attain a satisfactory filtering flow rate.
In Example 4, the apparatus 1A of which the outline is shown in FIG. 4 was used. Copper-containing water to be treated was supplied to the precipitation tank 2A, and a sodium hydroxide solution was added thereto to alkalize the solution and to precipitate copper hydroxide. The precipitation and mixing tank 2A was provided with the drum heater 22, so that a temperature of the precipitation tank was controlled to 60.degree. C. Further, a filter aid was directly supplied from the filter aid tank 5 to the precipitation and mixing tank 2A to prepare a mixed slurry of the copper precipitate and the filter aid. The filter aid slurry was sent to the solid-liquid separator 3, so that a film of the filter aid is formed on the filter, and the copper compound was removed. The filtrate was a weakly alkaline treated liquid from which copper was removed and may be discharged through a neutralization tank and, alternatively, is usable as cleaning water for the solid-liquid separator 3 or the magnet of the separation tank 4 or a liquid for preparing the filter slurry in the filter aid tank 5. After termination of the filtering of the treated water, the filter aid and a cake of the precipitated copper compound were present on the filter 33 inside the solid-liquid separator 3. Tap water was supplied from the upper line L10 of the solid-liquid separator 3 to remove ion components attached to the copper compound contained in the cake. After the ion removal, cleaning water was supplied from a lateral side of the filter 33 to disintegrate the cake, and the pieces were supplied to the separation tank 4. The separation tank 4 was provided with the stirring screw 41 and the electromagnet (magnetic separation mechanism), so that the filter aid and the copper compound were separated from each other while being mixed, and only the filter aid was captured by the magnet and recovered. The liquid from which the filter aid was recovered contained the copper compound at a high concentration and discharged. The filter aid recovered is cleaned with supplied cleaning water to be returned to the filter aid tank 5. The filter aid returned to the filter aid tank 5 was supplied again to the precipitation and mixing tank 2A to be reused.
As the water to be treated, a copper sulfate solution containing 1000 mg/L of copper was provided. The water to be treated was supplied to the precipitation tank 2A, and 48% sodium hydroxide was added thereto by dropping to adjust a pH value of the treated water to pH 10. After mixing for a certain period of time, precipitation of light blue copper hydroxide was confirmed. The drum heater 17 was operated to raise a water temperature to 60.degree. C., and mixing was performed at the temperature. After that, blackened part was observed, resulting in confirmation of the generation of copper oxide.
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