EP0946765A1 - Procede et dispositif de recuperation hydrometallurgique du zinc - Google Patents

Procede et dispositif de recuperation hydrometallurgique du zinc

Info

Publication number
EP0946765A1
EP0946765A1 EP97933768A EP97933768A EP0946765A1 EP 0946765 A1 EP0946765 A1 EP 0946765A1 EP 97933768 A EP97933768 A EP 97933768A EP 97933768 A EP97933768 A EP 97933768A EP 0946765 A1 EP0946765 A1 EP 0946765A1
Authority
EP
European Patent Office
Prior art keywords
residue
desired product
solid residue
mixed
process according
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP97933768A
Other languages
German (de)
English (en)
Inventor
Robert Alexander Lloyd
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.)
TETRA EUROPE Ltd
Original Assignee
TETRA EUROPE 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 TETRA EUROPE Ltd filed Critical TETRA EUROPE Ltd
Publication of EP0946765A1 publication Critical patent/EP0946765A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/006—Wet processes
    • C22B7/007—Wet processes by acid leaching
    • 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
    • C22B19/00—Obtaining zinc or zinc oxide
    • C22B19/28—Obtaining zinc or zinc oxide from muffle furnace residues
    • 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
    • C22B19/00—Obtaining zinc or zinc oxide
    • C22B19/30—Obtaining zinc or zinc oxide from metallic residues or scraps
    • 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
    • C22B19/00—Obtaining zinc or zinc oxide
    • C22B19/34—Obtaining zinc oxide
    • 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
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
    • C22B3/44—Treatment or purification of solutions, e.g. obtained by leaching by chemical processes
    • 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
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/006—Wet processes
    • 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
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/04—Working-up slag
    • 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 process for recovering zinc or other desired products from waste and process residues, in particular, but not exclusively those blast furnace residues produced from zinc smelting and steel making (oxygen) operations.
  • Waste and process blast furnace slags often contain substances which are valuable and/or difficult to dispose of, for example, containing hazardous metals and/or toxins.
  • There are many known ways of removing such products from the solid residue such as ion exchange, solvent extraction or precipitation processes.
  • the TETRA Europe Ltd High Density Sludge (HDS) Direct Recycle and Thickened Recycle processes are particularly useful in the removal of such products by precipitation.
  • the present invention seeks to provide a method and apparatus to recover desirable constituents from a waste product .
  • a process for recovering a desired product from a mixed-solid residue comprising the steps of:
  • step c) treating the mixed-solid residue with an acid to make the desired product soluble in the leachate; b) leaching the desired product into the leachate from the mixed-solid residue; c) separating the desired product from the leachate by a precipitation process forming a precipitation residue and the desired product; d) recirculating at least part of the precipitation residue to step a) and/or adding at least some of the waste-solid residue directly to step c).
  • a process for recovering a desired product from a residue which includes the step of recirculating either a residue formed in one stage of the process to an earlier stage of the process or the solid waste residue to a later stage of the process.
  • the invention uses these residues as a reagent in the step to which the residue is recirculated and thus reduces the amount of reagents which have to be added to the overall process thus reducing the cost of running the process.
  • the earlier stage of the process is prior to a treatment step where acid is added to lower the pH of the waste being treated.
  • the recirculation of the residue has the advantage for example of reducing the amount of acid required. Further, the recirculation step seems to assist the separation of desired products from the waste and generally improve the efficiency of the process, especially in the preferred and illustrated embodiments of the invention.
  • a recovery apparatus for recovering a desired product from a mixed-solid residue comprising:
  • the present invention thus provides a practical method of recovery from residues for many different metals and compounds and has particular utility when applied to zinc recovery. It is believed that the invention will make it viable to treat different types of waste.
  • the residue is prepared to make it more susceptible to size reduction, to physical separation of desired products, and to solubilising of desired products in a leach solution.
  • the preparation step comprises using the residue as a reagent in leachate neutralisation or pH adjustment and precipitation to selectively precipitate the desired products.
  • the refluxing of residue is continued back along the various stages until finally the residue is refluxed to the first step, e.g. to the size reduction plant. Over this multi-stage reflux recirculates the residue from the separation stages to the treatment stage.
  • the prepared and size-reduced residue is treated with combinations of sulphuric, hydrochloric and nitric acids to make the desired products soluble in the leach solution.
  • the residue may be entrained in water before passing through the acids leaching process; or residue may be reacted directly with the acids before passing through the water dilution process.
  • the separating step c) comprises treating the leachate in a system selected from the group consisting of: a precipitation process; an ion exchange process; a solvent extraction process; and mixtures thereof.
  • the treatment step e) consists of treating the leachate in one or more high density sludge (HDS) processes operating in parallel and/or series.
  • HDS high density sludge
  • residue in the HDS processes is particularly advantageous to use residue in the HDS processes as the neutralising agent.
  • the residue is separated from the HDS underflow sludge and refluxed to the prior neutralising stage and ultimately to the size reduction plant for final preparation before physical separation of desired products and leaching of desired products in the leaching solution.
  • the act of reflux reduces the amount of neutralising agent required and the power required to size reduce the residue.
  • the high calcium oxide content of the residue readily reacts with acid leach solution, and thus provides the additional benefits of acting as a neutralising agent. This leads to the breaking the internal structure of the vitreous residue which has the effect of reducing power consumption of the size reduction process and improve physical separation of desired products.
  • Figure 1 schematically illustrates a multi-stage recovery process according to a preferred embodiment of the invention.
  • Figure 1 depicts a particularly preferred embodiment for recovering zinc and other materials from blast furnace slag.
  • Waste residue is fed in to the process and in the illustrated embodiment the size of the residue particles are reduced in a size reduction step.
  • the size reduction step reduces the typically 3mm uniformly-sized vitreous particles to about 50 - 200 micron particles size.
  • size reduction step may not be required in other embodiments depending on the initial size of the waste particles and the separation steps which are to be employed.
  • the reduced-sized particles then undergo a physical separation step where products such as lead, gold and silver are recovered by density and/or magnetic means.
  • products such as lead, gold and silver are recovered by density and/or magnetic means.
  • the precise nature of this step will depend upon the constitution of the waste and this step may not be required in some cases.
  • the waste then undergoes a series of leaching operation to leach desired products in to the leachate.
  • water is used as the major constituent of the leachate. from the different separation operations.
  • the leaching operation may be in batch or continuous stirred tank reactors, or by plug flow pipe reactor means. Unwanted solid materials are removed from the leachate by, for example, gravity means with residue dewatered to produce a cake.
  • the leachate is then treated (neutralised) in a series of treatment stages to selectively precipitate desired products at each stage.
  • the preferred illustrated embodiment shows a four treatment stage process, but the number and nature of the treatment stages will vary depending upon the constitution of the waste and the desirability/necessity of recovering the various constituents from the waste.
  • each treatment stage is conducted at a different pH to form different precipitates containing the desired products at each stage.
  • the first treatment stage uses calcium carbonate to adjust the pH of the leachate to about pH2 to precipitate calcium sulphate dihydrate (gypsum) . If alternatively a different compound or mixture of compounds was used instead of calcium carbonate then the precipitate may, of course, differ.
  • the gypsum is recovered from the precipitate following dewatering and drying in a normal fashion.
  • the second treatment stage uses lime to adjust the pH of the leachate to about pH6 to pH7 to precipitate principally ferric/ferrous hydroxide. If a different base was used instead of lime then an alternative iron salt may be formed. The iron product is recovered as a cake following dewatering of the sludge.
  • the pH of the leachate is further adjusted to about pH8 to pH9 with more lime to precipitate principally ferric hydroxide, aluminium hydroxide, copper hydroxide and arsenic.
  • ferric salts may be added to the leachate to co-precipitate iron with arsenic. If a different base was used instead of lime then an alternative precipitate may be formed.
  • the pH of the leachate is further adjusted to about pHlO to pHll with more lime to precipitate principally zinc hydroxide.
  • the zinc hydroxide may be recovered through dewatering of the sludge to produce a zinc hydroxide cake or alternatively the hydroxide can be combined with an acid to form a different salt such as zinc sulphate, zinc chloride or zinc bromide.
  • the initial waste residue or size-reduced residue
  • the at least some of the residue is added to the final (fourth) separation stage. From the fourth stage the residue is further refluxed upstream to the third separation stage and then refluxed to second separation stage and then on to the first separation stage.
  • the precipitate residue from the separating means e.g. the underflow sludge of a HDS reactor
  • the precipitate residue from the separating means is recirculated back to the treatment stage. It is most preferred if the precipitate residue is recirculated and the waste-solid residue is added to the separating means as this maximises the befits of the present invention.
  • the actual number of refluxes and the precise nature and direction of a reflux will depend on the particular recovery process being adopted. Generally however the reflux operation provides a way of significantly reducing the amount of reagent needed in some separation stages and therefore significantly improves the efficiency and cost- effectiveness of the overall process. It is preferred if at least one of the separation stage ⁇ comprises a high density sludge (HDS) treatment and then the refluxed residue can be taken from the underflow sludge of the HDS process.
  • HDS high density sludge
  • the process is further advantageously enhanced by using the leaching technique of adding acid directly to the residue and subsequently diluting the product with water.
  • This technique minimises the hydrolysis of silica in the residue and minimises the formation of aluminium silicate/ ' silicic acid compounds which may affect the subsequent leachate neutralisation and precipitation processes.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Metallurgy (AREA)
  • Environmental & Geological Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Processing Of Solid Wastes (AREA)

Abstract

Procédé pour récupérer un produit voulu dans un résidu et dispositif prévu à cet effet. Le procédé consiste à recycler soit un résidu formé lors d'un étape du processus dans une étape antérieure du processus ou à recycler les déchets solides dans une étape ultérieure du processus. Dans le procédé de l'invention, on utilise ces résidus comme réactifs dans l'étape dans laquelle le résidu est recyclé et cela permet de réduire ainsi la quantité de réactifs devant être ajoutés pour l'ensemble du processus, ce qui diminue le coût du processus. L'étape antérieure du processus précède un étape de traitement comprenant l'addition d'acide pour abaisser le pH des déchets en cours de traitement. Le recyclage du résidu présente notamment l'avantage de réduire la quantité d'acide nécessaire.
EP97933768A 1996-07-30 1997-07-25 Procede et dispositif de recuperation hydrometallurgique du zinc Withdrawn EP0946765A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB9615946 1996-07-30
GB9615946A GB9615946D0 (en) 1996-07-30 1996-07-30 Zinc recovery process
PCT/GB1997/002023 WO1998004752A1 (fr) 1996-07-30 1997-07-25 Procede et dispositif de recuperation hydrometallurgique du zinc

Publications (1)

Publication Number Publication Date
EP0946765A1 true EP0946765A1 (fr) 1999-10-06

Family

ID=10797711

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97933768A Withdrawn EP0946765A1 (fr) 1996-07-30 1997-07-25 Procede et dispositif de recuperation hydrometallurgique du zinc

Country Status (5)

Country Link
EP (1) EP0946765A1 (fr)
AU (1) AU3701197A (fr)
GB (1) GB9615946D0 (fr)
WO (1) WO1998004752A1 (fr)
ZA (1) ZA976788B (fr)

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4610722A (en) * 1985-01-31 1986-09-09 Amax Inc. Process for metal recovery from steel plant dust
US4670051A (en) * 1985-03-19 1987-06-02 Hydrochem Developments Ltd. Oxidation process for releasing metal values in which nitric acid is regenerated in situ
GB8928368D0 (en) * 1989-12-15 1990-02-21 Sherritt Gordon Ltd Recovery of metal values from zinc plant residues
ZA928157B (en) * 1991-10-25 1993-06-09 Sasox Processing Pty Ltd Extraction or recovery of metal values.
DE4230223A1 (de) * 1992-09-10 1994-03-17 Hoechst Ag Verfahren und Anlage zum Entfernen von Blei, Cadmium und Zink aus Stäuben
FR2705102B1 (fr) * 1993-05-12 1995-08-11 Rhone Poulenc Chimie Procede de traitement de compositions contenant des metaux precieux et autres elements de valeur en vue de leur recuperation.

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9804752A1 *

Also Published As

Publication number Publication date
AU3701197A (en) 1998-02-20
GB9615946D0 (en) 1996-09-11
ZA976788B (en) 1998-02-11
WO1998004752A1 (fr) 1998-02-05

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