EP0621905A1 - Process for the reduction of hexavalent chromium contained in the residue resulting from the processing of chromium minerals - Google Patents

Process for the reduction of hexavalent chromium contained in the residue resulting from the processing of chromium minerals

Info

Publication number
EP0621905A1
EP0621905A1 EP93902135A EP93902135A EP0621905A1 EP 0621905 A1 EP0621905 A1 EP 0621905A1 EP 93902135 A EP93902135 A EP 93902135A EP 93902135 A EP93902135 A EP 93902135A EP 0621905 A1 EP0621905 A1 EP 0621905A1
Authority
EP
European Patent Office
Prior art keywords
sulphur
process according
chromium
hexavalent chromium
mixture
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Withdrawn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
EP93902135A
Other languages
German (de)
English (en)
French (fr)
Inventor
Giuseppe Bruzzone
Diego Perrone
Giacomo Bruno
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.)
Luigi Stoppani SpA
Original Assignee
Luigi Stoppani SpA
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 Luigi Stoppani SpA filed Critical Luigi Stoppani SpA
Publication of EP0621905A1 publication Critical patent/EP0621905A1/en
Withdrawn legal-status Critical Current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
    • C22B34/00—Obtaining refractory metals
    • C22B34/30—Obtaining chromium, molybdenum or tungsten
    • C22B34/32—Obtaining chromium
    • 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
    • C22B5/00—General methods of reducing to metals
    • C22B5/02—Dry methods smelting of sulfides or formation of mattes
    • C22B5/08—Dry methods smelting of sulfides or formation of mattes by sulfides; Roasting reaction methods
    • 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 concerns a new reduction process for hexavalent chromium contained in the earth resulting from the production of chromium, in order to obtain the transformation from water-soluble compounds into insoluble compounds.
  • the invention also concerns a plant for carrying out the above-mentioned process.
  • a normal reducing agent such as ferrous sulphate, ferrous chloride etc. , which reduce the chromium from CrO to Cr 0 , which is
  • the aim of the present invention is to solve the above problems by means of a process and a plant which will enable the carrying out of the reduction of hexavalent chromium compounds present in the resultant earth, in an alkaline environment and in a simple, 25. economical and efficacious manner.
  • This aim has been achieved by means of the present invention, which concerns a process for the reduction of hexavalent chromium in the residual products from the processing of chromium minerals, characterized in that it comprises the phases of mixing the said residual products with one or more reducing agents and of indirectly heating the said mixture substantially without the presence of oxygen.
  • the invention concerns a plant for the reduction of 5.
  • sulphur is used as a reducing agent, which, preferably, is mixed with the residual earths, previously dried and then heated to a temperature at least equal to that of sublimation (about 445°C) .
  • the process operates 15. continuously, by means of an indirect heat, sealed rotary furnace, and without the circulation of gases.
  • the residual products 1 of the leaching (or resultant earth) are dried (A) in an already known way, until they are substantially dry and then mixed in 2 (phase B) with sulphur, with
  • the preferred reagent is sulphur, and reference will be made to it now in the description which follows, without intending in this way to restrict the area of protection of the present invention.
  • the ratio of residual earth: sulphur is generally between
  • the dry mixture obtained in this way is fed to the reactor 3, which is preferably an indirect heat rotary furnace, provided with sealing 20.
  • the reactor 3 which is preferably an indirect heat rotary furnace, provided with sealing 20.
  • means 4 and 5 located at its ends and in any case on every possible opening, so as to avoid, or reduce to the minimum, the entry of air and in order to operate substantially without the presence of oxygen.
  • the phases of drying, mixing and feeding to the reactor 3 can follow any succession in time, even if the order described above is the 25. preferred one.
  • the external heating system 6 which is shown diagrammatically as a series of burners, furnishes the reactor with heat to sublime the sulphur, which is at this point capable of reacting, by removing oxygen from the compounds present in the residual products and reducing the hexavalent chromium.
  • the minimum 10. temperature is that of the sublimation of sulphur and the preferred reaction temperature is of about 500-550°C.
  • the process is carried out without the presence of oxygen and without the circulation of gases, since the atmosphere of sulphur and SO generated by the reaction is sufficient 15. to obtain the required conditions of reducing atmosphere.
  • the treated residual products 7 do not contain any appreciable quantity of hexavalent chromium (see the examples given below) .
  • the reacted sulphur becomes fixed in the material in the form of reducing salts (sulphites, sulphates, 25. etc.), which are possibly capable of reducing traces of hexavalent chromium which, because of difficulty in contact due, for example, to the high granulometry of the residual products, were not reduced during the reaction.
  • the mixture thus obtained is placed, in a platinum tank, in a tubular laboratory muffle and kept at 510°C (inside temperature) for two hours.
  • the phases of insertion and extraction of the sample take place in a flow of nitrogen to avoid oxidation phenomena arising from the presence of air.
  • the hexavalent chromium in the final product is always lower than 5 ppm.
  • the mixture obtained in this way is placed, in a platinum tank, in a tubular laboratory muffle and kept at 490°C (inside temperature) for
  • the hexavalent chromium in the final product is always lower than 5 ppm.
  • the mixture obtained in this way is placed, in a platinum tank, in a tubular laboratory muffle and kept at 680°C (inside temperature) for 30 minutes.
  • the phases of insertion and extraction of the sample are carried out in a nitrogen flow, in order to avoid oxidation phenomena caused by the presence of air.
  • the hexavalent chromium in the final product is always lower than 5 ppm.
  • the hexavalent chromium in the final product is always lower than 5 5. ppm.
  • the operation is carried out at an inside temperature of 510-520°C in 15. conditions such as to allow a stay time of 25-30 minutes.
  • the hexavalent chromium is always lower than 5 ppm.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Processing Of Solid Wastes (AREA)
  • Treatment Of Water By Oxidation Or Reduction (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Removal Of Specific Substances (AREA)
EP93902135A 1992-01-21 1992-12-29 Process for the reduction of hexavalent chromium contained in the residue resulting from the processing of chromium minerals Withdrawn EP0621905A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
IT92MI92 IT1262918B (it) 1992-01-21 1992-01-21 Procedimento ed impianto per la riduzione del cromo esavalente contenuto nei residui della lavorazione dei minerali di cromo
ITMI92092 1992-01-21
PCT/EP1992/003007 WO1993014232A1 (en) 1992-01-21 1992-12-29 Process and plant for the reduction of hexavalent chromium contained in the residue resulting from the processing of chromium minerals

Publications (1)

Publication Number Publication Date
EP0621905A1 true EP0621905A1 (en) 1994-11-02

Family

ID=11361603

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93902135A Withdrawn EP0621905A1 (en) 1992-01-21 1992-12-29 Process for the reduction of hexavalent chromium contained in the residue resulting from the processing of chromium minerals

Country Status (14)

Country Link
EP (1) EP0621905A1 (pl)
CN (1) CN1074948A (pl)
AU (1) AU3347593A (pl)
BR (1) BR9207057A (pl)
CZ (1) CZ170394A3 (pl)
IT (1) IT1262918B (pl)
MX (1) MX9300307A (pl)
PL (1) PL171592B1 (pl)
RO (1) RO110458B1 (pl)
RU (1) RU2096511C1 (pl)
SK (1) SK84194A3 (pl)
TR (1) TR26598A (pl)
WO (1) WO1993014232A1 (pl)
ZA (1) ZA9343B (pl)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE602006004968D1 (de) * 2005-02-08 2009-03-12 Cromotecnica Mexico Sa De Cv Verfahren und anlage zur umwandlung von chromhaltigem gefährlichem abfall in ungefählriche abfälle
EP2870107B1 (de) * 2012-07-06 2018-01-17 LANXESS Deutschland GmbH Verfahren zur reduktion von sechswertigem chrom in oxidischen feststoffen

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1055953B (it) * 1976-02-24 1982-01-11 Stoppani P & Co Procedimento di decontaminazione di materiale di scarto proveniente dalla lavorazione di minerali di cromo mediante trattamento conzolfo per via umida
JP2655864B2 (ja) * 1988-03-14 1997-09-24 昭和電工株式会社 高還元クロム鉱石粉体の製造方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9314232A1 *

Also Published As

Publication number Publication date
IT1262918B (it) 1996-07-22
RO110458B1 (ro) 1996-01-30
ITMI920092A1 (it) 1993-07-21
CZ170394A3 (en) 1995-08-16
ITMI920092A0 (it) 1992-01-21
RU94044672A (ru) 1996-08-27
SK84194A3 (en) 1995-08-09
PL171592B1 (pl) 1997-05-30
RU2096511C1 (ru) 1997-11-20
BR9207057A (pt) 1995-12-05
ZA9343B (en) 1993-08-05
TR26598A (tr) 1995-03-15
AU3347593A (en) 1993-08-03
CN1074948A (zh) 1993-08-04
MX9300307A (es) 1993-12-01
WO1993014232A1 (en) 1993-07-22

Similar Documents

Publication Publication Date Title
US5516971A (en) Process for disposal of waste propellants and explosives
US5458866A (en) Process for preferentially oxidizing sulfides in gold-bearing refractory ores
CH668823A5 (de) Verfahren zur vernichtung gefaehrlicher kohlenstoffhaltiger abfaelle.
WO1995012001A1 (en) Recovery of precious metal values from refractory ores
CN104487388B (zh) 用于还原氧化固体中的六价铬的方法
US4384923A (en) Process for the hygienization of carbonation sludges
US4332584A (en) Recovery of potential energy and chromium values from leather tannery wastes
US6336967B1 (en) Method for processing chromium oxide-containing substances in large quantities, method for utilizing the processed substances, and products comprising the processed substances
DK3218308T3 (en) PROCEDURE FOR REDUCING SEX EQUAL CHROME IN OXIDIC SOLIDS
US4086319A (en) Recovery of chromium from tannery waste
US4127390A (en) Hydrodesulfurization of coal and the like
WO1993014232A1 (en) Process and plant for the reduction of hexavalent chromium contained in the residue resulting from the processing of chromium minerals
US3803032A (en) Method for insolubilizing water soluble chromate in chrome waste residue
Ugarte et al. Characterisation of high-temperature arsenic-containing residues from hydrometallurgical processes
CA1047706A (en) Iron oxide based pigment and process for preparing such a pigment
US5013356A (en) Process for the processing of slag from aluminium scrap and waste melting, recovery of components thereof and treatment of gasses generated
CN1031934C (zh) 硫磺的提纯方法
US5236676A (en) Pressure chlorination of refractory gold ores
US3097988A (en) Process for regenerating black liquor
US60514A (en) William hendekson
WO1995023240A1 (en) A process for extraction of uranium
US5755853A (en) Process for the treatment of solid residues containing metals, in particular residues from the cleaning of household garbage incineration smoke
US5725632A (en) Method for processing and utilizing metalliferous presipitates from the gas cleaning phase in thermal waste treatment
US6001316A (en) Method for treatment of waste material and recovering MgCl2
KR800000090B1 (ko) 알파- Fe₂O₃형 산화철 안료의 제조방법

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19940707

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE GB IT

17Q First examination report despatched

Effective date: 19941213

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19960529