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US3095363A - Calcination of zinc sulfide concentrates - Google Patents

Calcination of zinc sulfide concentrates Download PDF

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Publication number
US3095363A
US3095363A US9177A US917760A US3095363A US 3095363 A US3095363 A US 3095363A US 9177 A US9177 A US 9177A US 917760 A US917760 A US 917760A US 3095363 A US3095363 A US 3095363A
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United States
Prior art keywords
zinc
concentrate
sulfate
zinc sulfide
sulfide
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Expired - Lifetime
Application number
US9177A
Inventor
Kurt F Ruckwardt
Bernard T Mcdonald
John F Mahoney
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Atlantic Richfield Co
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Anaconda Co
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Publication date
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Priority to US9177A priority Critical patent/US3095363A/en
Priority to GB63/61A priority patent/GB911833A/en
Priority to BE599429A priority patent/BE599429A/en
Application granted granted Critical
Publication of US3095363A publication Critical patent/US3095363A/en
Anticipated expiration legal-status Critical
Assigned to ATLANTIC RICHFIELD COMPANY, A PA CORP. reassignment ATLANTIC RICHFIELD COMPANY, A PA CORP. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: ANACONDA COMPANY THE, A DE CORP
Expired - Lifetime legal-status Critical Current

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    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01GCOMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G9/00Compounds of zinc
    • C01G9/02Oxides; Hydroxides
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B1/00Preliminary treatment of ores or scrap
    • C22B1/02Roasting processes
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B19/00Obtaining zinc or zinc oxide
    • C22B19/02Preliminary treatment of ores; Preliminary refining of zinc oxide
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B19/00Obtaining zinc or zinc oxide
    • C22B19/34Obtaining zinc oxide

Definitions

  • the invention is particularly directed to the provision of a method for improving the oxidation of the zinc sulfide in the concentrate, and is based on the discovery that when a minor amount of a metallic sulfate is incorporated in the concentrate prior to roasting, the oxidation of sulfide-sulfur is markedly improved and the amount of residual sulfidesulfur which remains in the resultant calcine is substantially decreased.
  • the zinc content of most ores, as mined, is generally too low for economical metallurgical treatment, and all processes developed for the winning of metallic zinc from its ores invariably require that the zinc minerals in the ore be concentrated to a point Where they may be recovered economically. Because Zinc sulfide, which is the most common zinc mineral found in zinciferous ores, cannot be reduced directly, these concentrates are roasted or calcined to produce zinc oxide (or sulfate) which, in turn, is more chemically reactive than zinc sulfide.
  • the zinc calcine is leached with dilute sulfuric acid to form an aqueous electrolytic solution of Zinc sulfate, which is initially purified to remove certain deleterious impurities and then is electrolyzed to produce metallic zinc, using an insoluble anode.
  • the solvent employed in leaching the zinc calcine is the spent electrolyte which remains after the electrolysis of the zinc sulfate solution and which contains up to about 25 percent by weight of sulfuric acid. Since any residual sulfide-sulfur remaining in the zinc calcine is insoluble in sulfuric acid and represents a loss in zinc equal to approximately twice its weight, one of the major objects in roasting the zinc sulfide concentrate is to convert the zinc sulfide, as nearly completely as possible, into zinc oxide and sulfate. Only enough Zinc sulfate shouldbe formed, however, to compensate for acid losses in the cycle, since any excess will result in a build-up of acid in the system.
  • any metallic sulfate may be used, particularly satisfactory results have been obtained by adding a minor amount of zinc sulfate to the zinc sulfide concentrates prior to roasting, the resultant calcine containing a much lower sulfide-sulfur content than can be obtained by roasting the concentrate absent the metallic sulfate under identical process conditions.
  • the invention contemplates the improvement, in a process in which a Zinc sulfide concentrate is roasted in an oxidizing atmosphere to convert the zinc sulfide to zinc oxide, of incorporating a minor amount of a metallic sulfate in the Zinc concentrate prior to roasting, Whereby oxidation of the sulfur content of the concentrate is substantially improved and the amount of residual sulfide-sulfur remaining in the calcine product is substantially decreased.
  • the actual concentration of the metallic sulfate added to the concentrate prior to roasting is,
  • the improvement contemplated by the invention is particularly applicable in the electrolytic process for the recovery of zinc from its ores, in which a zinc sulfide concentrate is roasted in an oxidizing atmosphere to convert the zinc sulfide to zinc oxide and a minor proportion of zinc sulfate and the resulting zinc calcine is leached with dilute sulfuric acid to form an aqueous electrolytic solution of zinc sulfate from which metallic zinc is electrodeposited.
  • the zinc sulfide concentrate By incorporating a minor amount of the electrolyte (equivalent to from about 0.5 to about 1 percent by weight of zinc sulfate) in the zinc sulfide concentrate prior to roasting, it is possible to increase the conversion of the sulfur content of the concentrate to oxide (and sulfate) and to decrease the amount of residual zinc sulfide remaining undissolved after the sulfuric acid leach.
  • the electrolyte equivalent to from about 0.5 to about 1 percent by weight of zinc sulfate
  • Table I sets forth the metallurgical results of a series of tests in which a zinc sulfide concentrate containing varying amounts of added zinc sulfate was roasted at a temperature of about 920 C.
  • an aqueous solution of zinc sulfate was added to an aqueous pulp of the zinc sulfide concentrate to uniformly distribute the sulfate throughout the concentrate. The pulp was then flashdried and roasted in a fiuosolids reactor.
  • a Zinc sulfide concentrate is roasted in an oxidizing atmosphere to convert the zinc sulfide to Zinc oxide
  • the improvement which comprises incorporating from about 0.5 to about 1 percent by weight of Zinc sulfate in the zinc sulfide concentrate prior to roasting to substantially improve oxidation of the sulfur content of the concentrate and to substantially decrease the amount of residual sulfide-sulfur remaining in the calcine product.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)

Description

United States Patent Ofiice 3,095,363 Patented June 25, 1963 3,095,363 CALCINATION OF ZINC SULFIDE CONCENTRATES Kurt F. Ruckwardt, Bernard T. McDonald, and John F. Mahoney, Anaconda, Mont, assignors to The Anaconda Company, a corporation of Montana No Drawing. Filed Feb. 17, 1960., Ser. No. 9,177 2 Claims. (Cl. 204-119) This invention relates to the calcination or roasting of zinc Sulfide concentrate in an oxidizing atmosphere to convert the zinc sufide to zinc oxide. The invention is particularly directed to the provision of a method for improving the oxidation of the zinc sulfide in the concentrate, and is based on the discovery that when a minor amount of a metallic sulfate is incorporated in the concentrate prior to roasting, the oxidation of sulfide-sulfur is markedly improved and the amount of residual sulfidesulfur which remains in the resultant calcine is substantially decreased.
The zinc content of most ores, as mined, is generally too low for economical metallurgical treatment, and all processes developed for the winning of metallic zinc from its ores invariably require that the zinc minerals in the ore be concentrated to a point Where they may be recovered economically. Because Zinc sulfide, which is the most common zinc mineral found in zinciferous ores, cannot be reduced directly, these concentrates are roasted or calcined to produce zinc oxide (or sulfate) which, in turn, is more chemically reactive than zinc sulfide. In the electrolytic zinc process, for example, the zinc calcine is leached with dilute sulfuric acid to form an aqueous electrolytic solution of Zinc sulfate, which is initially purified to remove certain deleterious impurities and then is electrolyzed to produce metallic zinc, using an insoluble anode.
The solvent employed in leaching the zinc calcine is the spent electrolyte which remains after the electrolysis of the zinc sulfate solution and which contains up to about 25 percent by weight of sulfuric acid. Since any residual sulfide-sulfur remaining in the zinc calcine is insoluble in sulfuric acid and represents a loss in zinc equal to approximately twice its weight, one of the major objects in roasting the zinc sulfide concentrate is to convert the zinc sulfide, as nearly completely as possible, into zinc oxide and sulfate. Only enough Zinc sulfate shouldbe formed, however, to compensate for acid losses in the cycle, since any excess will result in a build-up of acid in the system.
Using a range of roasting temperatures of 900 C. to 930 C., we have found that it is possible to increase the conversion of sulfide-sulfur in the calcine to oxide and to decrease the amount of residual sulfide-sulfur remaining in the calcine by adding a minor amount of sulfate ions in the form of a metallic sulfate to the zinc sulfide concentrate prior to roasting. Although any metallic sulfate may be used, particularly satisfactory results have been obtained by adding a minor amount of zinc sulfate to the zinc sulfide concentrates prior to roasting, the resultant calcine containing a much lower sulfide-sulfur content than can be obtained by roasting the concentrate absent the metallic sulfate under identical process conditions.
The invention contemplates the improvement, in a process in which a Zinc sulfide concentrate is roasted in an oxidizing atmosphere to convert the zinc sulfide to zinc oxide, of incorporating a minor amount of a metallic sulfate in the Zinc concentrate prior to roasting, Whereby oxidation of the sulfur content of the concentrate is substantially improved and the amount of residual sulfide-sulfur remaining in the calcine product is substantially decreased. The actual concentration of the metallic sulfate added to the concentrate prior to roasting is,
of course, dependent upon several factors, including the sulfide-sulfur content of the concentrate as well as the 5 temperature at which the concentrate is roasted. Al-
though there appears to be no critical upper limit on the amount of metallic sulfate added to the concentrate, there is no great advantage in using more than about 1 percent by wei-ght (calculated as sulfate). In most zinc sulfide concentrates, substantially the full benefit of the presence of the metallic sulfate may be achieved by adding a total of about 0.5 to about 1 percent by Weight, calculated as sulfate.
The improvement contemplated by the invention is particularly applicable in the electrolytic process for the recovery of zinc from its ores, in which a zinc sulfide concentrate is roasted in an oxidizing atmosphere to convert the zinc sulfide to zinc oxide and a minor proportion of zinc sulfate and the resulting zinc calcine is leached with dilute sulfuric acid to form an aqueous electrolytic solution of zinc sulfate from which metallic zinc is electrodeposited. By incorporating a minor amount of the electrolyte (equivalent to from about 0.5 to about 1 percent by weight of zinc sulfate) in the zinc sulfide concentrate prior to roasting, it is possible to increase the conversion of the sulfur content of the concentrate to oxide (and sulfate) and to decrease the amount of residual zinc sulfide remaining undissolved after the sulfuric acid leach.
To illustrate the applicability of incorporating a minor amount of zinc sulfate in the Zinc sulfide concentrate prior to roasting in accordance With the invention, Table I sets forth the metallurgical results of a series of tests in which a zinc sulfide concentrate containing varying amounts of added zinc sulfate was roasted at a temperature of about 920 C. In each of these tests, an aqueous solution of zinc sulfate was added to an aqueous pulp of the zinc sulfide concentrate to uniformly distribute the sulfate throughout the concentrate. The pulp was then flashdried and roasted in a fiuosolids reactor.
TABLE I Metallurgical Assays of Zinc Calcine [Percent by weight] Analysis of the data in Table I illustrates the general rule that the addition of a minor amount of a metallic sulfate to the zinc sulfide concentrate prior to roasting results in an increased conversion of sulfide-sulfur in the resultant calcine to sulfate-sulfur (or oxide), and thereby decreases the amount of residual zinc sulfide remaining undissolved after the calcine is leached with sulfuric acid.
Although the foregoing tests demonstrate the effectiveness of employing minor amounts of zinc sulfate in the Zinc sulfide concentrate prior to roasting, similar advantages are attained by dispersing any metallic sulfate throughout the concentrate prior to roasting. Consequently, the invention is applicable to the use of any metallic sulfate in the zinc sulfide concentrate to improve the calcining properties of the concentrate.
We claim:
1. In a process in which a Zinc sulfide concentrate is roasted in an oxidizing atmosphere to convert the zinc sulfide to Zinc oxide, the improvement which comprises incorporating from about 0.5 to about 1 percent by weight of Zinc sulfate in the zinc sulfide concentrate prior to roasting to substantially improve oxidation of the sulfur content of the concentrate and to substantially decrease the amount of residual sulfide-sulfur remaining in the calcine product.
2. In an electrolytic process for the recovery of zinc from its ores, in which a zinc sulfide concentrate is roasted in an oxidizing atmosphere to convert the zinc sulfide to zinc oxide and the resulting zinc oxide calcine is leached with dilute sulfuric acid to form an aqueous electrolytic solution of Zinc sulfate from which metallic zinc is electrodeposited, the improvement which comprises incorporating from about 0.5 to about 1 percent by weight of zinc sulfate from said electrolyte in the zinc sulfide concentrate prior to roasting to substantially improve oxidation of the sulfur content of the concentrate and to notably decrease the amount of residual zinc sulfide remaining undissolved after the sulfuric acid leach.
References Cited in the file of this patent UNITED STATES PATENTS Re. 12,105 Carmichael Apr. 21, 1903 588,076 Mohr Aug. 10, 1897 715,024 Clancy et a1 Dec. 2, 1902 1,153,203 Drefahl Sept. 14, 1915 1,183,172 Saulles 2- May 16, 1916 1,241,966 Hartley Oct. 2, 1917 1,255,439 Laist et a1 Feb. 5, 1918 1,727,073 Moyer et a1. Sept. 3, 1929 1,969,567 Tee Aug. 7, 1934 2,134,528 Mitchell Oct. 25, 1938 FOREIGN PATENTS 22,077 Great Britain Apr. 24, 1913 325,455 Great Britain Feb. 20, 1930 338,886 Great Britain Nov. 27, 1930

Claims (1)

1. IN A PROCESS IN WHICH A ZINC SULFIDE CONCENTRATE IS ROASTED IN AN OXIDIZING ATMOSPHERE TO CONVERT THE ZINC SULFIDE TO ZINC OXIDE, THE IMPROVEMENT WHICH COMPRISES INCORPORATING FROM ABOUT 0.5 TO ABOUT 1 PERCENT BY WEIGHT OF ZINC SULFATE IN THE ZINC SULFIDE CONCENTRATE PRIOR TO ROASTING TO SUBSTANTIALLYIMPROVE OXIDATION OF THE SULFUR CONTENT OF THE CONCENTRATE AND TO SUBSTANTIALLY DECREASE THE AMOUNT OF RESIDUAL SULFIDE-SULFUR REMAINING IN THE CALCINE PRODUCT.
US9177A 1960-02-17 1960-02-17 Calcination of zinc sulfide concentrates Expired - Lifetime US3095363A (en)

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US9177A US3095363A (en) 1960-02-17 1960-02-17 Calcination of zinc sulfide concentrates
GB63/61A GB911833A (en) 1960-02-17 1961-01-02 Improvements in calcination of zinc sulfide concentrates
BE599429A BE599429A (en) 1960-02-17 1961-01-24 Calcination of zinc sulphide concentrates

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3655538A (en) * 1969-05-19 1972-04-11 Texas Gulf Sulphur Co Process for electrowinning zinc from sulfide concentrates

Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US588076A (en) * 1897-08-10 Bernard mohr
US715024A (en) * 1901-03-02 1902-12-02 John Collins Clancy Extracting metals from complex or sulfid ores.
GB191322077A (en) * 1913-10-01 1914-10-01 Samuel Wilson Amphlet Improvements in Couplings for Attaching Water Driven Vibrators or Massage Apparatus to Water Taps.
US1153203A (en) * 1914-04-15 1915-09-14 Grasselli Chemical Co Method of treating ores.
US1183172A (en) * 1914-10-17 1916-05-16 Charles A H De Saulles Process of roasting zinc-blende.
US1241966A (en) * 1916-06-05 1917-10-02 Bully Hill Copper Mining & Smelting Company Zinc-extraction process.
US1255439A (en) * 1916-07-10 1918-02-05 Anaconda Copper Mining Co Process of recovering zinc from ores.
US1727073A (en) * 1926-08-10 1929-09-03 Mayer Process for the recovery of zinc from slags
GB325455A (en) * 1929-01-05 1930-02-20 Nouvelle Montagne Sa Improvements in or relating to the preparation of blende for sintering
GB338886A (en) * 1929-08-27 1930-11-27 Nat Processes Ltd Improvements in or relating to the blast roasting or sintering of ores and metallurgical materials
US1969567A (en) * 1932-08-06 1934-08-07 Cons Mining & Smelting Co Process for the treatment of zinc sulphide ores
US2134528A (en) * 1935-01-10 1938-10-25 Hughes Mitchell Processes Inc Treatment of lead bearing cres and the preparation of compounds therefrom

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US588076A (en) * 1897-08-10 Bernard mohr
US715024A (en) * 1901-03-02 1902-12-02 John Collins Clancy Extracting metals from complex or sulfid ores.
GB191322077A (en) * 1913-10-01 1914-10-01 Samuel Wilson Amphlet Improvements in Couplings for Attaching Water Driven Vibrators or Massage Apparatus to Water Taps.
US1153203A (en) * 1914-04-15 1915-09-14 Grasselli Chemical Co Method of treating ores.
US1183172A (en) * 1914-10-17 1916-05-16 Charles A H De Saulles Process of roasting zinc-blende.
US1241966A (en) * 1916-06-05 1917-10-02 Bully Hill Copper Mining & Smelting Company Zinc-extraction process.
US1255439A (en) * 1916-07-10 1918-02-05 Anaconda Copper Mining Co Process of recovering zinc from ores.
US1727073A (en) * 1926-08-10 1929-09-03 Mayer Process for the recovery of zinc from slags
GB325455A (en) * 1929-01-05 1930-02-20 Nouvelle Montagne Sa Improvements in or relating to the preparation of blende for sintering
GB338886A (en) * 1929-08-27 1930-11-27 Nat Processes Ltd Improvements in or relating to the blast roasting or sintering of ores and metallurgical materials
US1969567A (en) * 1932-08-06 1934-08-07 Cons Mining & Smelting Co Process for the treatment of zinc sulphide ores
US2134528A (en) * 1935-01-10 1938-10-25 Hughes Mitchell Processes Inc Treatment of lead bearing cres and the preparation of compounds therefrom

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3655538A (en) * 1969-05-19 1972-04-11 Texas Gulf Sulphur Co Process for electrowinning zinc from sulfide concentrates

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BE599429A (en) 1961-05-16
GB911833A (en) 1962-11-28

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AS Assignment

Owner name: ATLANTIC RICHFIELD COMPANY, A PA CORP.

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:ANACONDA COMPANY THE, A DE CORP;REEL/FRAME:003992/0218

Effective date: 19820115