FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION (See section 10 and rule 13)
TITLE OF THE INVENTION
METHOD FOR RECOVERY OF COPPER FROM COPPER REFINERY BLEED
APPLICANTS
Hindalco Industries Limited
Of address
Ahura Centre, 1st Floor, B-Wing,
Mahakali Caves Road, Andheri (East), Mumbai 400030, Maharashtra
PREAMBLE TO THE DESCRIPTION The following specification particularly describes this invention and the manner in
which it is to be performed:

FIELD OF INVENTION
[001] The present invention relates to an attempt to a novel process for selective copper value recovery from copper refinery waste bleed for sustainable economic benefits.
BACKGROUND OF THE INVENTION
[002] Copper is high conductor of electricity and have various application. Copper manufacturing process involves mining, concentration enrichment, smelting and refining.
[003] Copper refining process is carried out through electrochemical reaction, where copper anode with 99.5% purity and SS mother blank are placed at equal distance in a cell filled with copper sulphate solution. Copper from anode get dissolved and deposited on mother blank through electrochemical reaction and produces high purity cathode as product.
[004] During copper refining process, heavy metal impurities like nickel, arsenic, tellurium, selenium, bismuth and antimony dissolve is electrolyte solution. Some of impurities like gold, silver, selenium settles down as slime which is further processed for precious metal recovery.
[005] To maintain electrolyte quality in operating limits, some impure electrolyte is taken out from cells and further processed in electrowining system to recovery copper partially. Further treated electrolyte contains 2-20gpl cu content and 2-8gpl arsenic which is presently sent to effluent treatment process as refinery bleed for neutralization with lime slurry and hazardous solid waste. Bleed neutralization process generates hazardous gypsum containing metal values like copper, nickel as hydroxide, which is loss to company.

[006] These wastes are hazardous in nature, since they contain sulfuric acid and other impurities such as Cu, Ni, Pb, Zn, Fe, Sb and As etc. and they contaminate the surface and ground water causing direct threat to environment and health. The heavy and toxic metals, cadmium, arsenic, mercury chromium, nickel, lead, copper, and zinc are considered deleterious to the environment, when their concentrations are more than the stipulated limits. Metal industry waste and their characterization are listed in several publications.
[007] Generally, along with refinery bleed/effluent large amount heavy metal like copper, nickel, tellurium, and zinc get lost as value with solid waste which could be recovered economically. Several attempts have been made to recover such value from refinery waste bleed/effluent.
[008] Also based on the literature survey it was found that heavy metals like copper, nickel, zinc and tellurium could be precipitated selectively using various precipitating reagents, thus idea was generated to attempt to recover heavy metal value from waste copper refinery bleed/effluent to produce marketable/recyclable product compound. Also, nowhere in the literature it is mentioned that copper refinery bleed could be treated for metal value recovery using reagent like S-based and carbonates.
[009] Accordingly, there has been a need to develop an effective method to separate heavy metal impurities from copper refining from the copper manufacturing industry for making the effluent recyclable and recovery of metal value recovery.
OBJECT OF INVENTION
[010] The primary objective of the invention is to recover copper value from waste refinery bleed as a recyclable product having commercial value thus value recovery waste.

[011] It is therefore decided to invent a process for recovering copper value from waste refinery bleed as a recyclable product having commercial value thus value recovery waste.
SUMMARY OF THE INVENTION
[012] In an aspect, the invention provides a method for recovery of copper from copper refinery bleed. The method comprises of
a) pre-treating said refinery bleed at a pH in the range of 1-2;
b) treating refinery bleed of step (a) with a precipitating agent thereby selectively
precipitating cupper sulphide; and
c) drying of precipitated copper sulphide. In an aspect, the precipitating agent used is
a sulphur based reagent.
[013] The copper refinery bleed is pre-treated for removal of non-dissolved solid and pH adjustment through fine filtration followed by pH control through controlled dosing of lime slurry Controlled reaction of water soluble sodium based reagents to the refinery bleed to selectively precipitate out copper as copper sulphide.
[014] The product copper sulphide cake is dried in tray type electrical furnace and analyzed for copper purity and heavy metal impurities, wherein the heating temperature is in range of 120°C to 200°C. Controlled addition of lime slurry and ferrous sulphate to the treated effluent obtained from step to precipitate out gypsum and arsenic.
BRIEF DESCRIPTION OF DRAWINGS
[015] The foregoing summary, as well as the following detailed description of the invention will be better understood when read in conjunction with the appended drawings. For the purpose of assisting in the explanation of the invention, there are shown in the

drawings embodiments which are presently preferred and considered illustrative. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown therein. In the drawings
[016] Figure 1 is a flowchart of pre-treatment copper refinery bleed and selective copper precipitation
[017] Figure 2 is a process flow diagram for copper recovery.
[018] Figure 3a is a representation of the reactor for recovery of copper and figure 3b is the representation of perforated dosing system.
DETAILED DESCRIPTION OF THE INVENTION
[019] In describing and claiming the invention, the following terminology will be used in accordance with the definitions set forth below. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described herein. As used herein, each of the following terms has the meaning associated with it in this section. Specific and preferred values listed below for individual process parameters, substituents, and ranges are for illustration only; they do not exclude other defined values or other values falling within the preferred defined ranges.
[020] As used herein, the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise.
[021] The terms “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of

one or more preferred embodiments does not imply that other embodiments are not
useful, and is not intended to exclude other embodiments from the scope of the
invention.
As used herein, the terms "comprising" "including," "having," "containing,"
"involving," and the like are to be understood to be open-ended, i.e. to mean including
but not limited to.
Although any methods and materials similar or equivalent to those described herein can
be used in the practice or testing of the present invention, the preferred methods and
materials are described. All publications and other references mentioned herein are
incorporated by reference in their entirety. Numeric ranges are inclusive of the numbers
defining the range.
The use of examples anywhere in this specification including examples of any terms
discussed herein is illustrative only, and in no way limits the scope and meaning of the
invention or of any exemplified term. Likewise, the invention is not limited to various
embodiments given in this specification.
As used herein, the term "copper refinery bleed" refers to copper refinery acidic effluent
post treatment in three stage of electrowinning.
As used herein, the term "precipitating agent" refers to as chemical solution which
preferentially reacts with copper available in the copper refinery bleed and precipitate
it as copper sulphide.
As used herein, the term "copper smelter" refers to processing units which separate
elemental copper from copper concentrates through multiple sulphide oxidizing stages.
During copper refining process, to maintain electrolyte quality in operating limits, some
impure electrolyte is taken out from cells and further processed in electrowining system
to recovery copper partially. Further treated electrolyte contains 2-5gpl cu content and

2-8gpl arsenic which is presently sent to effluent treatment process as refinery bleed for
neutralization with lime slurry and produces hazardous solid waste. During
neutralization process of refinery bleed 2-5 gpl coper value lost with hazardous waste
as hydroxide.
Large amount heavy metal such as copper, nickel, tellurium, and zinc are lost along
with copper refinery bleed. These heavy metals can be recovered from copper refinery
bleed economically and several attempts have been made to improve the recovery of
such heavy metals from copper refinery bleed.
Based on the knowledge that heavy metals like copper, nickel, zinc and tellurium could
be precipitated selectively using various precipitating reagents, the inventors of the
application attempted to recover heavy metal value from waste copper refinery
bleed/effluent to produce marketable/recyclable product compound.
The prior known bleed neutralization process for recovery of copper value copper
refinery bleed generates hazardous gypsum containing metal values like copper, nickel
as hydroxide, which is not desirable.
In an embodiment, a method for recovery of copper from copper refinery bleed
comprising the steps of:
a) pre-treating said refinery bleed at a pH in the range of 1 -2;
b) treating refinery bleed of step (a) with a precipitating agent thereby selectively precipitating cupper sulphide; and
c) drying of copper sulphide precipitate of step (b).
In an embodiment, pre-treating of step (a) comprises of filtering of refinery bleed to remove non-dissolved solids. The pH during pre-treating is maintained by a compound selected from a group consisting of calcium carbonate, calcium oxide or sodium hydroxide.

In an embodiment, the precipitating agent of step (b) is selected from a group consisting
of hydrogen sulphide, sodium hydrosulfide or barium sulphide. In an embodiment, the
concentration of precipitating agent is in the range of 10-20%. In an embodiment, said
precipitating agent is sprayed into the refinery bleed through a dosing system.
In an embodiment, the drying of step (c) is performed in at a temperature in range of
120°C to 250°C.
In an embodiment, the method further comprises of smelting of dried copper sulphide
for obtaining copper.
The concentration of copper in dried copper sulphide obtained in step (c) is in the range
of47to60%.
As shown in the Figure 1, the waste refinery bleed (-20% H20S4,) was pre-treated
through fine filtration to remove undissolved solids and the pH of the bleed is adjusted
to around 2 in equalizer.
Pre-treated mother liquor is transferred to reactor and 10% sodium hydrogen sulfide is
dosed under beneath surface in controlled manner for around 1 hour to selectively
precipitate copper. After completion of reaction, the slurry was filtered in vacuum/plate
type of filter.
Filtrate is analysed for end point (copper less than 100 ppm) and sent to effluent
treatment step where lime slurry and ferrous sulphate dosed to neutralized to pH 7 and
precipitate gypsum and heavy metal impurities like arsenic, nickel and iron. The copper
sulphide cake obtained from filter is washed with steam and dried at 150°C in tray type
electrical furnace and analysed for copper purity and heavy metal impurities and sent
copper smelter for further processing for making copper cathode with 99.99%) purity
Figure 2, shows detail scheme, for innovative process modification, design, and
commercialization for sustainable economic benefits.

] The precipitating agent has high affinity towards copper present in the refinery bleed and instantaneously precipitates copper as copper sulphide. High mixing and de localized mixing one of the most important parameter in the reaction.
] It is known in the art that improper mixing of precipitating agent result in the emission of hydrogen sulphide gas. Conventionally 5% caustic solution is sprayed is sprayed from top which reacts with H2S to neutralize the harmful gas. The caustic solution is replaced after an interval 6 months.
] A major drawback of localized addition of precipitating agents in prior art method is that, it leads to hydrogen sulfide gas generation which results in higher reagent consumption and environmental risk.
To overcome the drawback, the present invention provides an innovative dosing and gas scrubbing system. In an embodiment, the invention provides a process which controls the emission of hydrogen sulfide (H2S) from source. In an embodiment, in step (b) the precipitating agent is sprayed onto the refinery bleed through a perforated dosing system for homogenous mixing thereby reducing formation hydrogen sulphide gas. The perforated dosing system of the invention ensures that there must an available copper cation for every sulphide.
Figure 3 is illustration of the reactor for recovering copper from coper refinery bleed having perforated dosing system of the invention. The reactor for recovering copper from coper refinery bleed comprising, a cylindrically elongated container having a top surface, bottom surface and a continuous side surface extending from top surface to bottom surface thereby defining a housing; said housing having at least one inlet port and at least one outlet port; and a cylindrically elongated tube extending inwardly from top surface having a first end and a second end, a continuous circular tube having at

least two nozzles connected to the second end of said elongated tube defining a dosing
system.
The reactor as claimed in claim 11, wherein said continuous circular nozzles comprises
of at least six nozzles placed at uniform distance.
The diameter of said nozzle is in the range of 12 mm to 15 mm placed at uniform
distance of 785 mm.
The dosing system is connected to a feed stream for feeding sodium sulphide solution
at a controlled rate 100-300 liters per hour through said cylindrical elongated tube.
In an embodiment, the dosing system is placed about 1.5 m deep from top surface of
the reactor. The positioning of the dosing system ensures that H2S reacts with the
copper cations above the dosing system. The perforated dosing system of the invention
innovation reduces the burden on scrubber system by >95%.
The controlled dosing of sodium sulfide solution through perforated uniform
distribution system provided effective copper precipitation and avoid localized reaction
forming hydrogen sulfide gas at surface as per reaction (ii) below since H2S further
react with available Cu in vicinity and form CuS as per reaction (iii) below. Thus by
design there should be less than 10 H2S Gas generation & emission from reactor.

As hydrogen sulfide gas is environmental sensitive, to avoid any excess hydrogen sulfide generation, a gas scrubber system is connected to the outlet of the reactor to capture any H2S /acid fumes available at surface in reactor. This gas scrubber system includes 2.5m3 circulation tank, column, blower, and circulation pump. 5% NaoH

solution is used as scrubbing media which circulated at flow rate of 5m3/h. This system controls H2S emission in air less than 0.1 ppm.
WORKING EXAMPLE
STEP 1: PRE-TREATMENT OF RAW BLEED:
5 liters of copper refinery bleed was pre-treated through fine filtration with ultrafine paper with mesh size 40 and 42 for removal of undissolved matters. Pre-treatment of refinery bleed removed non-dissolved solid and the pH was adjusted through controlled dosing of 10% lime slurry.
STEP 2: SELECTIVE PRECIPITATION:
[054] Sodium hydrosulfide was added to the pre-treated refinery bleed obtained from step 1 to selectively precipitate out copper as copper sulphide (CuS). The addition of sodium hydrosulfide was performed through the perforated dosing system. Sodium hydrosulfide was added at a controlled dose to the pre-treated bleed under stirring conditions at temperature range 40-60 °C. The stoichiometric ratio of copper to sulphide ions was in the range of 1: 0.7 to 1: 0.9. Following are the chemical reaction happened in entire process of experiment

STEP 3: FILTRATION:
After completion of precipitation of cupper sulphide, the slurry was feed to vacuum filter. After filtration copper sulphide cake was obtained with 15-22% moisture contain.

STEP 4: PRODUCT WASHING:
[057] Copper sulfide cake obtained after filtration have 2-3% acid and 15-22% moisture was washed to remove acid content less than 1%.
STEP 5: PRODUCT DRYING:
[058] The copper sulphide (CuS) cake obtained from reaction was dried in tray type electrical furnace and analysed for copper purity and heavy metal impurities, wherein the heating temperature is in range of 120 to 200°C. The dried copper sulphide (CuS) obtained from step is sent to copper smelting section for production.
STEP 6: FILTRATE NEUTRALIZATION: [059] Controlled addition of lime slurry and ferrous sulphate to the treated effluent was
performed to precipitate out gypsum and arsenic. [060] The following parameter were considered to quantify the recovery of copper:
1. % Copper Recovery
2. % Copper Sulphide Purity
3. % Moisture in copper cake from filter.

Refinery Product Final Recovery H2S Conc.
Bleed Effluent
Cu: 3-10 gpl Cu: 45-60% Cu: <100 Cu: 95-99% H2S<20 ppm in
As: 4-6 gpl As <1% ppm As <10% reactor
H2SO4: 200- H2SO4:<05% As: 4-6 gpl H2SO4 <10% H2S <1ppm out
220 H2SO4: 190-210gpl Gas scrubber
Table 1 [061] As seen in the table above, the process of the application results in 99% recovery of copper from refinery bleeds.
EXAMPLE 2

STEP 1: PRE-TREATMENT OF RAW BLEED:
[001] 5 liters of copper refinery bleed was pre-treated through fine filtration with ultrafine paper with mesh size 40 and 42 for removal of undissolved matters. Pre-treatment of refinery bleed removed non-dissolved solid and the pH was adjusted through controlled dosing of 10% lime slurry.
STEP 2: SELECTIVE PRECIPITATION:
[002] Sodium hydrosulfide was added to the pre-treated refinery bleed obtained from step 1 to selectively precipitate out copper as copper sulphide (CuS). The addition of sodium hydrosulfide was performed through a conventional single point dosing system. Sodium hydrosulfide was added at a controlled dose to the pre-treated bleed under stirring conditions at temperature range 40-60 °C. The stoichiometric ratio of copper to sulphide ions was in the range of 1: 0.7 to 1: 0.9.
[003] Following are the chemical reaction happened in entire process of experiment
a) NaHS(aq) + CuSO4(aq) ----□ CuS(s) + Na2SO4(aq) (i)
b) Na2S(aq) + CuSO4(aq) -----□ CuS(s) + Na2SO4(aq) (ii)
STEP 3: FILTRATION:
[004] After completion of precipitation of cupper sulphide, the slurry was feed to vacuum filter. After filtration copper sulphide cake was obtained with 15-22% moisture contain.
STEP 4: PRODUCT WASHING:
[005] Copper sulfide cake obtained after filtration have 2-3% acid and 15-22% moisture was washed to remove acid content less than 1%.

STEP 5: PRODUCT DRYING:
[006] The copper sulphide (CuS) cake obtained from reaction was dried in tray type electrical furnace and analysed for copper purity and heavy metal impurities, wherein the heating temperature is in range of 120 to 200°C. The dried copper sulphide (CuS) obtained from step is sent to copper smelting section for production.
STEP 6: FILTRATE NEUTRALIZATION: [007] Controlled addition of lime slurry and ferrous sulphate to the treated effluent was
performed to precipitate out gypsum and arsenic. [008] The following parameter were considered to quantify the recovery of copper:
1. % Copper Recovery
2. % Copper Sulphide Purity
3. % Moisture in copper cake from filter.

Refinery Bleed Product Final Effluent Recovery H2S Conc.
Cu: 3-10 gpl As: 4-6 gpl H2SO4: 200-220 Cu: 45-60% As <1% H2SO4:<05% Cu: <100 ppm As: 4-6 gpl H2SO4: 190-210gpl Cu: 90-95% As <10%
H2SO4 <10% H2S~50 ppm in
reactor
H2S <1ppm out Gas
scrubber
[001] As seen in the table above, when dosing is done through localized feed the process of
the recovery of copper from refinery bleeds is less than as compared to copper recovery
when precipitating is dosed through perforated dossing system. [002] In addition, the concentration of hydrogen sulphide gas (H2S) emission during the
copper recovery using perforated dossing system is comparatively less as compared to
copper recovery process using single point dosing.

We Claim:
1) A method for recovery of copper from copper refinery bleed comprising the steps of:
a) pre-treating said refinery bleed at a pH in the range of 1-2;
b) treating refinery bleed of step (a) with a precipitating agent thereby precipitating copper
sulphide; and
c) drying of cupper sulphide precipitate of step (b).
2) The method as claimed in claim 1, wherein said precipitating agent is added through a
perforated dosing system.
3) The method as claimed in claim 1, wherein pre-treating of step (a) comprises of ultrafiltration of refinery bleed to remove non-dissolved solids.
4) The method as claimed in claim 1, wherein pH during pre-treating is maintained by calcium carbonate or calcium hydroxide.

5) The method as claimed in claim 1, wherein reagent of step (b) is selected from a group consisting of hydrogen sulphide, sodium hydrosulfide, barium sulphide.
6) The method as claimed in claim 1, wherein the concentration of precipitating agent is in the range of 15-20%.
7) The method as claimed in claim 1, wherein drying of step (c) is performed in at a temperature in range of 120°C to 200°C.
8) The method as claimed in claim 1, further comprising of smelting of dried copper sulphide for obtaining copper.
9) The method as claimed in claim 1, wherein the purity of dried copper sulphide obtained in step (c) is in the range of 98 to 99%.

10) The method as claimed in claim 1, wherein the copper concentration in dried copper
sulphide obtained in step (c) is in the range of 47 to 60%.
11) The method as claimed in claim 1, wherein the percentage of recovery of copper from the copper refinery bleed is greater 98%.
12) A reactor for recovering copper from coper refinery bleed comprising,
a cylindrically elongated container having a top surface, bottom surface and a
continuous side surface extending from top surface to bottom surface thereby defining
a housing;
said housing having at least one inlet port and at least one outlet port; and
a cylindrically elongated tube extending inwardly from top surface having a first end
and a second end, a continuous circular tube having at least two nozzles connected to
the second end of said elongated tube defining a dosing system.
13) The reactor as claimed in claim 11, wherein said dosing system is connected to a feed stream.
14) The reactor as claimed in claim 11, wherein said outlet is connected to a gas scrubbing system.
15) The reactor as claimed in claim 11, wherein length of said dosing system is 1.5 meters.
16) The reactor as claimed in claim 11, wherein diameter of said nozzle is in the range of 12mm to 15 mm.
17) The reactor as claimed in claim 11, wherein said continuous circular nozzles comprises of at least six nozzles placed at uniform distance.