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WO2017009667A1 - Dissolution de métal par de l'acide nitrique - Google Patents

Dissolution de métal par de l'acide nitrique Download PDF

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Publication number
WO2017009667A1
WO2017009667A1 PCT/GB2016/052161 GB2016052161W WO2017009667A1 WO 2017009667 A1 WO2017009667 A1 WO 2017009667A1 GB 2016052161 W GB2016052161 W GB 2016052161W WO 2017009667 A1 WO2017009667 A1 WO 2017009667A1
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WO
WIPO (PCT)
Prior art keywords
metal
nitric acid
oxygen
reaction
headspace
Prior art date
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Ceased
Application number
PCT/GB2016/052161
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English (en)
Inventor
David Crossley
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
William Blythe Ltd
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William Blythe Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by William Blythe Ltd filed Critical William Blythe Ltd
Publication of WO2017009667A1 publication Critical patent/WO2017009667A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G3/00—Compounds of copper
    • C01G3/08—Nitrates
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G1/00—Methods of preparing compounds of metals not covered by subclasses C01B, C01C, C01D, or C01F, in general
    • C01G1/08—Nitrates
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/20—Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
    • C01B21/48—Methods for the preparation of nitrates in general
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G15/00—Compounds of gallium, indium or thallium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G5/00—Compounds of silver

Definitions

  • the present invention relates to the dissolution of metals with nitric acid in an industrial process, being a process at a scale wherein the amount of metal being dissolved is upward of 10kg.
  • Metal nitrate Solutions are commonly prepared by reacting a metal, a metal oxide, a metal hydroxide or a metal carbonate with nitric acid.
  • a particular issue with the reaction of nitric acid with metals that are more electronegative than hydrogen is that, a mixture of NO and N0 2 , commonly referred to as NO x , is formed rather than hydrogen being liberated.
  • Commercially important metals in this category include copper, nickel, silver, indium and thallium.
  • gaseous Oxygen may be introduced into the gas phase or the liquid phase to improve the rate of NO to N0 2 oxidation and some designers advocate addition of oxidising agents such as Hydrogen Peroxide into the liquid phase - though this does carry it with it the risk of Hydrogen Peroxide decomposition if an accumulation is allowed to build up and then become acidified.
  • the dilute nitric acid recovered by this process may be returned to process if it is of a suitable concentration. However this normally means that it is necessary to concentrate the dilute acid by evaporation to make it usable, unless it is diverted for use in another application.
  • CN101698498A uses a feed of hydrogen peroxide in addition to the nitric acid that is charged to the reaction vessel.
  • the hydrogen peroxide acts as an oxidant that reacts with the NO and N0 2 gases.
  • this process has a narrow safety margin since the hydroxide may consistently decompose, particularly under acidic conditions.
  • JPS632704108 discloses the dissolution of copper solid with nitric acid in which a recirculating loop serves to spray the nitric acid over the copper and in doing so enables contact with atmospheric oxygen to enable a proportion of the NO x to be converted into nitric acid.
  • This process has difficulties since recirculation necessitates a pumping of a solution comprising suspended metal solids particles and the atomisation of the recirculating liquid so as to provide contact with atmospheric oxygen. This requires filters and these filters quickly become blocked since the metal dissolution process gives rise to continually finer metal particles.
  • CN103482591A discloses a copper dissolution at below atmospheric pressure at ⁇ 0.05MPa (0.5 Bar).
  • a further issue regarding metal dissolution using nitric acid is that it is desirable that the end product is a concentrated solution of metal nitrate with limited residual nitric acid content such as may be used directly for the manufacture of metal carbonate or mixed metal carbonate catalyst precursors without need for energetically expensive post-processing steps such as evaporative concentration or from which the metal nitrate may be readily isolated as a solid with minimal need for further processing of the mother liquor to render harmless the residual nitric acid content.
  • the present invention is a.
  • the metals used in metal dissolution to provide metal nitrates of the present invention are metals which react with nitric acid to produce nitric oxide and nitrogen dioxide, these are generally metals that are more electronegative than hydrogen (i.e. metals with a positive reduction potential as expressed electron volts). These are metals which are oxidized by nitric acid to cause them to go into solution and in so doing reduce the oxidation state of the nitrogen component of nitric acid from 4+ to 2+ thus causing its conversion from nitric to nitrous acid which then disproportionates to liberate NO and N0 2 .
  • a primary benefit of the present invention is that it permits metal nitrate solutions of concentrations close to saturation and with minimal free nitric acid content to be produced in a closed vessel with negligible release of NO x to atmosphere.
  • a secondary benefit of the present invention is that this process will achieve metal dissolution rates at least comparable with those achieved by conventional processes.
  • a third benefit of the present invention is that unlike conventional processes which uses a large excess of the metal and of nitric acid the process may be conducted using close to stoichiometric quantities of the metal and nitric acid to yield solutions with the required metal content without need for evaporation or post production processing to remove or neutralise un-reacted nitric acid.
  • a fourth benefit of the present invention is the prevention by imposition of a high degree of process control, of perturbations in reaction rate, for example, those caused by an accumulation of nitrous acid which would occur if the reaction is run below 50°C and which auto catalyses the reaction between nitric acid and metals and would lead to surges in NOx release which could overwhelm an external abatement system.
  • Achievement of the required reactions of the present invention preferably comprises one or more of the steps:
  • This may be achieved by use of an external circulation loop incorporating a heat exchanger but because of the risk of blockage and fouling due to the presence of un-dissolved metal and because of the risk of loss of containment consequent on the mechanical failure of the heat exchanger or circulation pump in the preferred embodiment of the invention this is achieved by use of reaction vessel heating /cooling coils and most preferentially coils on the outside of the reaction vessel and good bulk movement of the reactor contents achieved by the use of blades on the agitation system configured to achieve high liquid flows and hence good mass transfer.
  • nitric acid Feeding nitric acid to the process at a rate which is less than the rate at which nitric acid will react with the metal so that there is no risk of an accumulation of nitric acid developing with attendant risk of a run-away reaction occurring, and by then maintaining excess oxygen in the process; by using oxygen to ensure that nitrous acid and NO produced by the reaction between the metal and nitric acid are converted to nitric acid as soon as produced.
  • Oxygen to cause nitrous acid to be converted back to nitric acid and NO to be oxidised to N02 which is then reabsorbed to form nitric acid rather than inorganic oxidants such as Potassium Permanganate which would introduce impurities (manganese salts) to process or Hydrogen Peroxide Solution which is unstable in under acidic conditions and air which would introduce a mass of inert material to process (Nitrogen) which would have to be periodically purged from process to avoid filling the reactor head space with nitrogen thus creating the need for an abatement system to remove NO and N0 2 from the purge gas.
  • inorganic oxidants such as Potassium Permanganate which would introduce impurities (manganese salts) to process or Hydrogen Peroxide Solution which is unstable in under acidic conditions and air which would introduce a mass of inert material to process (Nitrogen) which would have to be periodically purged from process to avoid filling the reactor head space with nitrogen thus creating the need for an ab
  • Oxygen into the liquid phase to secure oxidation of nitrous acid to nitric acid in the liquid phase and thus minimise escape of NO and N0 2 to the head space.
  • This may be done by promoting absorption of oxygen from the head space into the liquid phase or by the use of an external circulation loop with an eductor to draw oxygen into the reaction system.
  • the reaction is promoted by the use of sintered metal diffusers which create micro bubbles of Oxygen which dissolve readily in the reaction system.
  • liquor surface area at the 'air/water' interface may be maximised by use the use of hollow shaft impellors configured to draw head space gasses into the reaction system and release them though the eye of an impellor, by the use of an agitation system designed to create a collapsing vortex at the liquor surface or by the use of an agitation system designed to create a mass of droplets at the liquor surface.
  • a single agitation system is used to agitate the metal particles, such as an impeller, to promote rapid renewal of the surface film around the metal particles (transport of reaction products from and reagents to metal surface), heat removal and gas re-absorption from the head space, thus eliminating all of the problems cause by use of some kind of external circulation/heat removal loop.
  • the use of the single agitation system to promote very good bulk liquid mixing within the reaction vessel combined with good heat transfer and use of fixed nitric acid addition rate and a constant head space Oxygen over-pressure also leads to homogeneous reaction conditions and thus minimises the risk of perturbations in reaction rate.
  • a further preferred feature is the circulation of head space gas into the nitric acid.
  • a preferred combination therefore includes a stirrer, having a stem with attached impellers.
  • the stem is preferably a hollow stem and arranged so that an upper end of the hollow stem accesses the head space and a lower end is in proximity to an impeller arranged to agitate the metal in the nitric acid that has a corresponding access from the hollow stem.
  • Head space gas may therefore be arranged to circulate from the head space to the impeller and this has been found to greatly accelerate the rate of reaction giving copper dissolution.
  • the impeller is preferably arranged so as to create a reduced pressure in the nitric acid liquid and so draw down gas from the head space trough the hollow stem as part of a stirring action of the impeller.
  • the impeller may comprise paddles having leading and trailing edges and giving rise to turbulence so as to create a reduced pressure at the trailing edge to provide the aforementioned effect of headspace gas recirculation.
  • the reactor vessel is charged with the batch stoichiometric requirement of water - this is a function of the desired end concentration of the metal nitrate solution and allows for the water added to process via the heel of metal nitrate solution added in the next stage.
  • a heel being a term of art describing a priming of the reaction vessel with a reacted solution composition (such as usually derived from a previous batch) which appears to 'kick start' the reaction and in particular the dissociation process so as to decrease reaction time. This is particularly effective for copper, silver indium and thallium metals.
  • the reactor is then preferably charged with a heel of the metal nitrate Solution which may be of the same concentration as the desired end product or at a proportionally greater concentration depending on the quantity of any additional water added. This may range from 1 to 100% by weight of metal batch charge but an amount of 30 to 40% by weight of metal batch charge has been found to be most beneficial in enhancing reaction start up kinetics.
  • the reactor is then charged with the metal in the form of chopped scrap, flakes or some other divided form which can be mobilised by the reactor agitation system.
  • the quantity of metal added may either be batch stoichiometric requirement or an excess may be added.
  • the reactor vessel is then closed up, head space purged with gaseous oxygen (such as to a local exhaust scrubber) to principally remove nitrogen from the head space and then head space pressure increased to a pressure greater than atmospheric - no upper limit on the working pressure has been identified but experience suggests that an optimal comprise between nitrate and oxide production reaction rate for copper, silver, indium and thallium is 1.0 to 5 bar - preferentially 2 bar to 3 bar and most preferably 2.4 to 2.6 bar.
  • chromium, cobalt, iron, nickel and aluminium it is 2 to 5 bar - preferably 3 to 4 bar most preferably 3.5 to 3.8 bar.
  • the reactor contents are then raised to a temperature between ambient and boiling point which is sufficient to suppress the formation of nitrous acid which can act as an autocatalyst - the optimum reaction temperature has been found to be in the range 60 to 80°C.
  • Nitric acid of the concentration necessary to achieve the required product composition - after allowing for water addition - is then metered into the reactor at a fixed rate and Oxygen is added to the reactor to maintain the head space pressure at the fixed value.
  • the rate of nitric acid addition is determined by the rate at which the reaction between nitric acid and the metal can be sustained within the reactor and is a function of the reactor design - experience suggests that rates as high as 2.0 gm metal dissolved/unit 100% HN0 3 added/minute are achievable
  • the oxygen supply rate is regulated to provide the oxygen needed to drive the oxidation of NO to N0 2 , preferably by a pressure controller to maintain a constant pressure in the vessel.
  • Oxygen may be introduced directly to the reactor head space or it may introduced subsurface via either a sparge pipe or preferentially sintered metal diffusers which generate microbubbles and so promote rapid absorption of oxygen
  • the rate of reaction is fixed by the rate of nitric acid addition and the reaction is complete when the batch requirement of nitric acid is added.
  • the reactor contents may then be settled to allow any excess metal to settle to the bottom of the reactor and then the contents of the vessel may be either completely discharged from the vessel or the made quantity may be removed leaving behind the heel which will be used in the subsequent batch.
  • the reactor headspace contains substantially oxygen which can be vented to a local effluent abatement system before the reactor is recharged.
  • renewal of the surface layer of the liquor around the metal may be achieved by an external circulation loop rather than by an agitation system - drawing liquor from either above or below the metal bed and circulating though the bed though preferentially the liquor should be circulated up though the bed to promote gas disengagement.
  • This embodiment would permit metal to be used in a form which could not be mobilised by agitation - e.g. bundles of wire or chopped plate.
  • the volume of the headspace is preferably between 0.5 and 5 times the volume of the nitric acid and no greater than 5 times. The reaction kinetics decreasing considerably above 5 times.
  • the headspace oxygen concentration may be made as high as 100% by weight, particularly at the end of reaction if operated as a batch process, so as to drive the reaction to completion and avoid a residual headspace requiring significant clean up before release to the atmosphere.
  • the initial headspace oxygen concentration may be at or near 100% by weight, particularly when used in conjunction of a heal of metal nitrate solution derived from a previous batch reaction of the process.
  • the reaction may be a batch reaction, this enables conversion to be driven to at or near 100% providing a metal nitrate product requiring no or minimal post processing. At or near can be defined as 95 to 100% by weight.
  • the oxygen concentration may be alternatively by weight in all instances as a secondary option.
  • the metal to be dissolved is copper. This may be due to the optimised reaction kinetics from the combination of higher pressure, low temperature and metal agitation in the acid, which is employed. This is also found also with thallium and indium; and to a lesser extent with silver, with a negligible effect for Gold.
  • the headspace may be absent carbon dioxide, which can poison the reaction pathway.
  • the headspace may comprise a noble gas, the noble gas may include helium (which for present purposes if defined as having no weight). This reduces the possibility of hazard at high oxygen levels.
  • Nitric acid for use in the present invention is preferably of a concentration from 50 to 80%, preferably 60 to 70% as HN0 3 by weight to optimise reaction rate of the whole process (as opposed to simply the reaction of the acid with the metal).
  • a concentration from 50 to 80%, preferably 60 to 70% as HN0 3 by weight to optimise reaction rate of the whole process (as opposed to simply the reaction of the acid with the metal).
  • iron, cobalt, chromium, nickel, and aluminium it is 10 to 20% by weight, to avoid passivation.
  • the total nitric acid present in relation to the metal to be dissolved is present from a stoichiometric molar equivalent to a 10% molar excess, preferably in the range of stoichiometric molar equivalent to 2% excess, most preferably at stoichiometric molar equivalent. Further preferably when used at a 2% excess or less when the oxygen concentration is set at 100% at the end of the reaction.
  • metal nitrate end product may be separated from residual metal by filtration the nitric acid level being low or exhausted.
  • the possibility does not benefit from high oxygen concentration as the residual reaction to remove the last nitric acid requires a slow reaction 'tail' raising the possibility of metal oxide creation.
  • MPa g and Bar g refer to pressure over atmospheric pressure as opposed to MPa or Bar which refer to absolute pressure.
  • 0.5 Bar would be below atmospheric pressure
  • 0.5 Bar g would be above atmospheric pressure.
  • atmospheric pressure is taken as 0.1 MPa or 1 Bar. If a conflict in units arises the values expressed in Bar prevail.
  • Alkali metals (Group I) and alkaline earth metals (Group II) and manganese liberate hydrogen in reaction with Nitric acid and are thus not suitable for use in the present invention.
  • Pure gold and platinum group metals do not react with nitric acid and are thus not suitable for use in the present invention.
  • Metalloids, which produce metal oxides with nitric acid are less desirable, particularly as the oxides may precipitate and hinder the reaction.
  • the metals copper, aluminium, chromium, cobalt, indium, iron, nickel, silver and thallium provide good yield with the method of the present invention.
  • the composition of the method of the present invention preferably consists of nitric acid and pure (>99%) metal having only incidental impurities and oxygen, this gives the cleanest product, which is usually considered to be the metal nitrate.
  • Organic substances are preferably absent as they can cause undesirable side reactions and/or foaming which reduce reaction efficiency.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)

Abstract

L'invention concerne un procédé rapide et efficace, à l'échelle industrielle, pour la production de solutions de nitrate métallique par dissolution d'un métal à l'aide d'acide nitrique, qui surmonte des exigences de traitement de NOx gazeux par la réaction des produits secondaires à base de NOx gazeux avec de l'oxygène dans la cuve de réaction. Le procédé est particulièrement utile pour la production de nitrate de cuivre, d'aluminium, de chrome, de cobalt, d'indium, de fer, de nickel, d'argent et de thallium.
PCT/GB2016/052161 2015-07-16 2016-07-15 Dissolution de métal par de l'acide nitrique Ceased WO2017009667A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB1512461.3A GB2540745A (en) 2015-07-16 2015-07-16 Metal dissolution with nitric acid
GB1512461.3 2015-07-16

Publications (1)

Publication Number Publication Date
WO2017009667A1 true WO2017009667A1 (fr) 2017-01-19

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WO (1) WO2017009667A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20230073103A1 (en) * 2020-02-06 2023-03-09 Chemtrade Solutions LLC System and method for manufacturing aluminum chlorohydrate
CN116216767A (zh) * 2023-03-29 2023-06-06 湖南海利高新技术产业集团有限公司 一种硝酸银的制备方法及装置

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5039502A (en) * 1989-02-02 1991-08-13 Hoechst Aktiengesellschaft Process for the preparation of metal nitrates
EP1352879A1 (fr) * 2002-03-28 2003-10-15 OM Group, Inc. Procédé de préparation de nitrates de métal à partir du métal correspondant
CN101481133A (zh) * 2009-02-11 2009-07-15 四川师范大学 硝酸铜溶液的制备方法

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5260294A (en) * 1975-11-12 1977-05-18 Fuji Photo Film Co Ltd Method for production of silver nitrate
JPS63270418A (ja) * 1987-04-27 1988-11-08 Tanaka Kikinzoku Kogyo Kk 金属類の硝酸により溶解方法
CN1029221C (zh) * 1992-11-04 1995-07-05 四川省环境保护科研监测所 无污染制备硝酸银溶液的方法
US6468494B2 (en) * 2000-11-29 2002-10-22 Om Group, Inc. Process for preparing metal nitrates from the corresponding metals
CN101698498A (zh) * 2009-10-28 2010-04-28 广东光华化学厂有限公司 一种制备电子级高纯硝酸铜溶液的清洁方法
CN103482591A (zh) * 2013-10-22 2014-01-01 严俊 一种铜系催化剂硝酸盐制造绿色过程方法

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5039502A (en) * 1989-02-02 1991-08-13 Hoechst Aktiengesellschaft Process for the preparation of metal nitrates
EP1352879A1 (fr) * 2002-03-28 2003-10-15 OM Group, Inc. Procédé de préparation de nitrates de métal à partir du métal correspondant
CN101481133A (zh) * 2009-02-11 2009-07-15 四川师范大学 硝酸铜溶液的制备方法

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20230073103A1 (en) * 2020-02-06 2023-03-09 Chemtrade Solutions LLC System and method for manufacturing aluminum chlorohydrate
CN116216767A (zh) * 2023-03-29 2023-06-06 湖南海利高新技术产业集团有限公司 一种硝酸银的制备方法及装置

Also Published As

Publication number Publication date
GB201612349D0 (en) 2016-08-31
GB2542248B (en) 2018-02-21
GB2540745A (en) 2017-02-01
GB2542248A (en) 2017-03-15
GB201512461D0 (en) 2015-08-19

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