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
  • C22B15/00—Obtaining copper
  • C22B15/0026—Pyrometallurgy
  • C22B15/0028—Smelting or converting
  • C22B15/005—Smelting or converting in a succession of furnaces
• • 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
  • C22B15/00—Obtaining copper
• • 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
  • C22B15/00—Obtaining copper
  • C22B15/0026—Pyrometallurgy
  • C22B15/0028—Smelting or converting
  • C22B15/0052—Reduction smelting or converting
• • 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
  • C22B15/00—Obtaining copper
  • C22B15/0026—Pyrometallurgy
  • C22B15/006—Pyrometallurgy working up of molten copper, e.g. refining
• • 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

• This invention relates to a method of intensive, continuous fire refining of blister copper or secondary copper.
• Fire refining of blister copper is carried out in stationary reverberatory or vascular furnaces, called anode furnaces due to the most common casting of refined copper in the form of anodes, which are transferred to electrolytical refining.
• Fire refining process is a classical batch process consisting of four stages: charging, oxidation and impurities slagging, reduction and anode casting. Time of refining cycle without the stage of melting varies from 6 to 14 hours.
• Oxidized copper after oxidation stage contains from 5000 to 10000 ppm of oxygen.
• the copper is reduced by carboneous or amonia reductant.
• the most common reductant in use are the oil or natural gas.
• the oil or natural gas are injected with air into the bath of molten copper through a tuyere or tuyeres.
• Copper reduction faces significant limitations in the process rate and efficiency of reductant utilisation.
• Reduction stage of the liquid copper charge which fluctuates from 150 to 400 t, varies in the range from 1.2 to 2.0 hours. Reported reductant efficiency is below 50%. Injection of liquid or gaseous reductant into the copper produces black fumes in off-gas due to thermal decomposition of hydrocarbons.
• Partial carbon utilisation in oxygen reduction from copper causes the presence of carbon particles in the reduction gases, which are partly combusted if the burner flame is oxidising. Carbon particles are transferred to the furnace off-gas, creating black fumes emitted through a chimney to the atmosphere.
• R. Nenych, F. Kadler and V. Sedlacek replaced the conventional reduction with wood by ammonia, what allowed for production of high quality copper.
• Ammonia consumption is about 1 kg/t of copper, when oxygen is reduced from 4000 a 1000 ppm. (R. Henych et al., "Copper refining by gaseous ammonia", J. of Metals, VoI 17, N°4, April 1955).
• N. Themelis and P.Schmidt have patented the deoxidisation of a liquid copper by injection of various reformed hydrocarbons (methane, ethane, butane) with steam, leading to the formation of the gas containing carbon monoxide and hydrogen. Patented installation was based on vascular furnace. ("Apparatus and process for the gaseous deoxidisation of molten metal, Canadian Patent N 0 827.066, November 1969).
• Figure 1 is a sketch illustrating schematically the principle of intensive, continuous fire refining of blister copper supplied from continuous Mitsubishi copper matte converting furnace.
• This invention refers to a pirometallurgical method of oxygen removal from a liquid copper by the use of solid carboneous reductant, charged on the surface of copper in addition to the injection of reductant through tuyeres or lances and simultaneous agitation of copper bath with inert gas introduced via porous plugs.
• the method in which carboneous reductant and hydrocarbons of oil or natural gas mixed with air or steam react with oxygen dissolved in copper results in high rate of reduction, shorten the time and increase of reductant efficiency.
• the invention leading to a method of oxygen extraction from a liquid copper consists of following stages:
• copper reduction (4) after oxidation and slagging of impurities, is carried out by injection of a liquid or gaseous reductant (oil, natutral gas) (3) with simultaneous addition of solid reductant (5) onto copper bath surface(4) and bath agitation with inert gas (1) through porous plugs (2)
• a liquid or gaseous reductant oil, natutral gas
• inert gas (1) Injection of inert gas (1) through the porous plug (2) prevents the formation of the gradient of oxygen content in the copper slowing down the rate of reaction. Continuous stirring of the copper bath in whole volume by inert gas (1) ensures the mass transfer onto the reaction surface (copper/charcoal).
• Floating charcoal or coke bed (5) on the copper (4) surface allows for higher flexibility of burner operation. Even in the case of oxidising flame the charcoal (5) is protecting copper against the oxidation, permitting for more efficient use of fuel and better control of copper temperature. Moreover, the excess oxygen in the burner allows for post- combustion of reduction gases (7) leaving the bath producing clean gases.
• This invention has following advantages compared with traditional methods of copper reduction: a) Application of solid carbon addition combined with bath stirring by nitrogen introduced by porous plugs during injection of liquid or gaseous reductant significantly shorten reduction time from 40 to 60% in comparison to common reduction practice. b) Efficiency of reductant (carbon and hydrocarbons) increases from 30 to 50% of the average values of traditional operation. c) Emission of gases with black fumes (carbon black) is drastically decreased reducing negative process impact on the environment. d) Higher reductant efficiency and shorter reduction time results in the decrease of unitary reductant and fuel consumption as well as in the increase of furnace productivity, e) Cost of method application is low. Necessary modifications of refining furnace are minor. f) EXAMPLE 1
• Copper refining is carried out in vascular anode furnace capacity of 150 t of copper as it is schematically illustrated in Figure 1.
• Four porous plugs (2) are mounted in the bottom part of the furnace.
• nitrogen (1) is injected into the molten copper (4).
• Nitrogen flowrate varies from 40 to 120 NmVh.
• Oxidation period is ended by skimming out of the slag.
• Oxygen content in the copper is in the level of 8000 ppm.
• 1.5 to 4 kg of charcoal (5) per tonne of copper is charged through the mouth onto copper surface.
• Flow of oil through one tuyere is put on (about 4 - 8 kg/h per tonne of copper) together with air (4 - 8 Nm 3 /h per tonne of copper).
• Furnace is tilted and the tuyere immersed starting to blow into the copper. Oil flowrate is increased gradually up to the point that black fumes are not emitted. Setting of the burner is changed. Oil flowrate through the burner is shut down and air flow is kept at the level of 3 - 20 Nm 3 /h per tonne of copper. Introduced air through the burner ensures effective post-combustion of reduction gases leaving the bath. Charcoal on the surface prevents the copper against oxidation. Produced off-gases leaving the furnace to a chimney are clean and acceptable for emission. After 45 min of reductant injection through the tuyere oil flowrate is put gradually down and the furnace is tilted putting tuyere above the bath. Next, oil and air flow is shut down. Oxygen content in copper is 400 - 800 ppm and the furnace is prepared for anode casting.
• Copper refining is carried out in stationary anode furnace of capacity 300 t of copper.
• porous plugs are installed in the bottom part of side wall against the wall with charging window. Nitrogen flowrate through porous plug is 0.3 - 1.0 Nm 3 Zh per tonne of copper. After finishing oxidation period and skimming out of refining slag the portion of 1.3 - 4.0 kg of charcoal per tonne of copper is charged through a window onto the copper surface.
• the oil flow is put on through a lance (2 - 5 kg/h per tonne of copper) together with air (2 - 5 Nm 3 /h tonne of copper). Lance is immersed into the copper and reduction. Burner is supplied by natural gas.
• Burner parameters are set: 1 - 3 Nm 3 /h of natural gas and 7 - 20 Nm 3 /h of air per tonne of copper. It ensures effective post- combustion of reduction gases and emission of clean off-gas to the atmosphere. After 100 min the lance is removed and the oil and air flows shut down. Oxygen content has been decreased from 6000 - 8000 ppm to about 400 - 800 ppm. Next, anode casting is proceeded.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacture And Refinement Of Metals (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=40935504

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (12)

Family Cites Families (9)

• 2005
  • 2005-09-06 WO PCT/US2005/031731 patent/WO2006029162A1/en not_active Ceased
  • 2005-09-06 MX MX2007002764A patent/MX2007002764A/es unknown
  • 2005-09-06 CA CA2579579A patent/CA2579579C/en not_active Expired - Fee Related
  • 2005-09-06 AU AU2005282475A patent/AU2005282475B2/en not_active Ceased
  • 2005-09-06 EP EP05796063A patent/EP2111472A4/de not_active Withdrawn
  • 2005-09-06 KR KR1020077007827A patent/KR20080100402A/ko not_active Withdrawn

Also Published As

Similar Documents

Legal Events