(MERAF) for the Base Metals Smelting Sector - CCME

3.2.11. Noranda Inc., Division CCR, Montréal, Québec 90
Figure 19 contains a schematic block flow diagram for the Copper Refinery
showing the general sequence of the major unit operations, from the receipt of
raw materials to the production of metals. When these unit operations are
referred to in the text, the corresponding words starts with an upper case letter.
This diagram is highly simplified and is included solely to aid in the discussion
and understanding of the pollution control at the facility.
The refinery removes very small quantities of metal impurities from feed
materials to produce high purity copper and other products. Most of the copper
anodes to be refined are received from Noranda’s copper smelters at Rouyn-
Noranda and Murdochville. Anodes are also produced from scrap purchased by
the refinery and may be purchased from other copper producers or refined on a
toll basis.
Anodes are refined by electrorefining in which a solution of sulphuric acid is used
as the electrolyte and direct current is applied to dissolve copper at the anode.
Impurities including precious and platinum group metals are distributed between
the electrolyte and the anode slimes. The copper cathode product is plated onto
copper starting sheets. Electrolyte is continuously withdrawn for removal of
nickel sulphate and other impurities such as arsenic, bismuth and antimony. The
nickel sulphate is sold, the recovered sulphuric acid is re-used in the tankhouse
and the impurities are recycled back to the smelters. Spent anodes are removed
from the cells after 21 days while approximately half of the cathodes are removed
from the cell every 10 or 11 days. A significant portion of the anode is not
dissolved. Spent anodes are remelted and cast into new anodes for
reprocessing. Off-gases from melting and anode casting are treated by a
baghouse prior to release to the atmosphere. Baghouse dust is returned to the
Horne smelter for recycling
Some of the cathodes produced are melted and cast into copper billets or other
shapes for the market, while most are sold directly. Off-gases from cathode
melting and casting are not treated prior to release to the atmosphere.
Anode slimes are washed from the spend anodes and removed from the cells for
further processing to recover precious, platinum group and specialty metals. The
slimes are first treated to remove tellurium and copper and then smelted in a Top
Blown Rotary Converter (TBRC). Solutions from the tellurium recovery stage are
further processed to produce metallic tellurium and copper sulphate.
The TBRC produces Doré anodes which are further refined to produce metallic
silver, gold and a platinum-palladium concentrate. TBRC slags are milled and
floated to recover a precious metals concentrate while the tailings are recycled to
the Horne Smelter. Dust, and volatile metals and metal oxides leave the TBRC
with the off-gas which is treated by wet scrubbing to remove dust and fume.
90 Hatch Associates, Review of Environmental Releases for the Base Metals Smelting Sector,
prepared for Environment Canada, dated November 2000
86