CA1153896A - Process for recovering copper - Google Patents
Process for recovering copperInfo
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- CA1153896A CA1153896A CA000344888A CA344888A CA1153896A CA 1153896 A CA1153896 A CA 1153896A CA 000344888 A CA000344888 A CA 000344888A CA 344888 A CA344888 A CA 344888A CA 1153896 A CA1153896 A CA 1153896A
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- 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
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Abstract
"PROCESS FOR RECOVERING COPPER"
ABSTRACT OF THE DISCLOSURE
A process for extracting copper from copper-containing materials comprises leaching in a first stage such materials with sulphuric acid to produce a cupric sulphate containing liquor, and treating such liquor with sulphur dioxide, preferably at substantially atmospheric pressure while maintaining the pH of the liquor at a level above 1, preferably between 1 and 3, in order to precipitate Chevreul's salt, and in a second stage heating the Chevreul's salt in the presence of water, or water and sulphur dioxide, or sulphurous acid, under pressure and optionally in the presence of a suitable modifying agent to yield metallic copper.
Magnesium oxide is the preferred modifying agent.
ABSTRACT OF THE DISCLOSURE
A process for extracting copper from copper-containing materials comprises leaching in a first stage such materials with sulphuric acid to produce a cupric sulphate containing liquor, and treating such liquor with sulphur dioxide, preferably at substantially atmospheric pressure while maintaining the pH of the liquor at a level above 1, preferably between 1 and 3, in order to precipitate Chevreul's salt, and in a second stage heating the Chevreul's salt in the presence of water, or water and sulphur dioxide, or sulphurous acid, under pressure and optionally in the presence of a suitable modifying agent to yield metallic copper.
Magnesium oxide is the preferred modifying agent.
Description
1153~91~ .
This invention relates to an improved method of extracting metallic copper from solutions containing copper and particularly from leach liquors obtained by leaching copper ores with sulphuric acid.
It is well known to extract copper by hydrometallurgical techniques involving the leaching of copper ores with sulphuric acid to provide a liquor containing cupric sulphate from which copper in metallic form can be recovered. In particular, the copper can be recovered by electrolytic techniques, and it has also been proposed to precipitate copper by saturating the cupriz sulphate solution with sulphur dioxide and heating the saturated solution under conditions of elevated temperature and pressure. These techniques do, however, have disadvantages. Thus the electrolytic techniques are expensive in terms of power consumption and manpower, whereas ~ome hydrometallurgical methods have not been able economically to produce metallic copper with high yields.
The present invention provides a process for extracting copper in a highly efficient manner, both quantitatively and economically, in a manner which has not been possible with methods proposed hitherto.
According to the present invention, copper is extracted from copper-containing materials, for example ores, roasted concentrates, scrap material~ or flue dusts recovered from copper smelting, by leaching in a first stage such materials with sulphuric acid to produce a cupric-sulphate containing liquor, treating such liquor with sulphur dioxide preferably at ~k, .. . ~
~1538~6i substantially atmospheric pressure while maintaining the pH
of the liquor at a level above l, preferably between l and 3, in order to precipitate Chevreul's salt, and in a second stage heating the Chevreul's salt in the presence of water, or water and sulphur dioxide, or sulphurous acid, and under pressure and optionally in the presence of a suitable modify-ing agent to yield metallic copper and suphuric acid.
By "modifying agent" is meant an agent which is designed to increase the yield of copper and/or to modify the form of the copper in order to prevent the copper adhering to the surfaces of the reaction vessels. Suitable second stage modifying agents include magnesium oxide, magnesium carbonate, sodium sulphate, sodium hydroxide, magnesium hydroxide and magnesium sulphate. The preferred agent is magnesium oxide.
In the first stage of the process of the present invention, as Chevreul's salt is precipitated the pH of the reactant solution tends to fall as a result of the reaction:
3 CuSO4 + 3 SO2 + 6H2 -~cu2so3-cuso3-2H2o ~ 4SO4- + 8H+
As the pH falls the precipitation of Chevreul's salt diminishes. This tendency can be reduced, i.e. the pH fall restrained by the addition of a suitable agent to control the pH or by recycling the remaining acidic liquor through a copper-containing ore or other material to leach out further copper. However, in the latter method, a point is reached where the copper content of the leach liquor reaches saturation so that no further copper can be leached out.
At this point it becomes desirable to add a suitable agent " 11531~6 to control the pH so as to precipitate the remaining copper as Chevreul's salt.
According to the present invention suitable first-stage modifying agents include sulphate-containing agents such as sodium sulphate or magnesium sulphate, or alkaline oxides or hydroxides such as sodium hydroxide, magnesium oxide, magnesium carbonate or magnesium hydroxide. The preferred agent is magnesium oxide or magnesium hydroxide. setween l.00 and 1.25 equivalents of magnesium oxide are preferred.
It is important that the pH controlling agent should produce a soluble by-product to avoid contamination of the precipitated Chevreul's salt - calcium oxide for example would be unsuitable for this reason and also because of the problems in disposing of the insoluble gypsum which would be formed. Magnesium oxide has been found particularly suitable as an economical control agent, and moreover the magnesium sulphate formed during the process is a valuable by-product which can contri-bute to the overall economic viability of the process of the invention.
By controlling the pH by the regulation of addition of sulphur dioxide and a modifying agent it is possible to precipitate substantially the whole of the copper from the liquor in the form of Chevreul's salt.
The first stage is desirably conducted at a temperature between 25 and 100C, preferably between 70 and 100C, and particularly between 90 and 95C. The p~ of the liquor is preferably maintained between about 2.08 and 3 during the first stage.
- In the second stage the Chevreul's salt is heated under conditions of elevated temperature and pressure to yield metallic copper and sulphuric acid:
.
~; B
., Cu2SO3.CuSO3.2H2O ~3Cu + 2H2SO4 The copper is recovered in pure form and the sulphuric acid can be recycled for leaching further ore.
The Chevreul's salt may be heated in an autoclave, preferably to a temperature between 100C and 170C, and particularly to a temperature in the vicinity of 150C.
Towards the upper part of the range colloidal sulphur is formed which contaminates the-copper. On the other hand, at temperatures below 150C the reaction rate tends to drop to a level which would eventually become uneconomic.
The pressure is not critical and is in any case determined by the operating temperature. Generally, the operating pressure will be within the range 160 - 200 p.s.i.
Although if Chevreul's salt is heated alone it would produce sulphur dioxide, it is preferred to conduct the autoclaving in the presence of added sulphur dioxide, either as such or in the form of sulphurous acid. The addition of a modifying agent may also be desirable.
The process according to the invention permits the precipitation of copper substantially quantitatively from leach liquors in the form of Chevreul's salt, and subsequently the recovery of metallic copper from the Chevreul's salt in a yield of substantially 100%. Such recoveries have not been possible using methods proposed hitherto.
As stated above, the process of the present invention permits the substantially complete recovery of copper from leach liquors with simultaneous production of sulphuric acid which is available for further leaching. This renders the process highly attractive economically having regard to the cost of transporting sulphuric acid to the usually remote sites where copper ore is mined, and also the current price of copper which makes the substantially 100% recovery permitted by the invention economically most attractive.
One embodiment of the process of the invention is described with particular reference to Figure 1 in which is illustrated a flow diagram schematically representing the steps of the process.
In Figure 1 sulphuric acid is sprayed onto an ore dump and copper sulphate-containing leach liquor is removed and pumped to an intermediate storage point. From there the liquor is pumped to a solvent extraction plant in which ferrous sulphate is removed and pumped to a barren liquor point in which it is bacterially converted to the ferric lS state and then returned to the ore dump with fresh sulphuric acid.
~, The concentrated copper containing liquor is pumped via intermediate storage to a reaction vessel to which is also supplied magnesium oxide for pH control, and sulphur dioxide which would be readily available from smelters associated with ore deposits. The magnesium oxide flow is controlled to provide a pH b~tween 1 and 3 within the reaction vessel.
Chevreul's salt is produced in the reaction vessel and is then transferred to a pressure vessel and heated at approximately 150C in the ~resence of sulphur dioxide and magnesium oxide to produce metallic copper and sulphuric acid which are separated in a filter, the copper being dried and recovered in a high degree of purity, the sulphuric acid 38~6 being returned to storage.
An alternative embodiment of the invention is illustrated in -the flowsheet of Figure 2, which schematically represents the steps of the process for the recovery of copper from S sulphide concentrates which are initially subjected to a fluid bed oxide roast.
It is preferred to operate the process of the invention in two separate stages, the first stage at atmospheric pressure and the second stage at elevated pressure, with separation of the liquor from the Chevreul's salt before the latter is heated in the second stage. It is however, possible to operate the two stages at elevated pressure without separation of the Chevreul's salt from the liquor between stages. It is however, important to adjust the pH appropriately if substantially quantitative yields of Chevreul's salt are to be obtained pr or to autoclaving.
1153~
The invention is described with particular reference to the following examples which are illustrative only.
FORMATION OF CHEVREUL'S SALT
3CuSO + 3SO2 + 6H2O _ ~ Cu2SO3.CuSO3.2H2O + 4SO4 + 8H
A solution of CuSO4.5 H20 (24.97 g in 500 ml, 0.2M or 1.27% Cu) was heated to 90C and SO2 was passed through for 30 minutes. A small amount only of Chevreul's salt was formed (Yield 15~).
A solution of NaOH (70 ml of 4M, 0.28 moles i.e. 1.05 times the H calculated to be formed on a 100% yield of Chevreul's salt) was added over a period of 20 mins. The mixture was cooled in ice to 5C and filtered, the solid being washed with water and then with acetone.
The yield of Chevreul's salt was 12.0 g (93%).
Magnesium Oxide Optimisation Study A solution of CUSO4. 5H2O (39.29 g in 500 ml or 2%Cu3 was heated to 90C and sparged with SO2. The magnesium oxide was added while the solution wàs vigorously stirred.
Stirring was continued with SO2 sparging for 30 minutes.
The reaction mixture was then cooled and Chevreul's salt isoleted and dried. See Table l for results.
.
.:
` ` ~
11538'36, In the following table "one equivalent of MgO" is defined as the amount of MgO needed to neutralise the acid formed upon a 100% yield of Chevreul'~ salt being obtained.
i,e. if x g/l Cu2 initially, then one equivalent of MgO is x x - x 231 = 0.846 x g/l MgO.
63.55 3 Initial Cu concentration 2%
Equivalent of MgO added % depletion of Cu 0.0 15 0.5 56 1.0 92 1.25 97.2
This invention relates to an improved method of extracting metallic copper from solutions containing copper and particularly from leach liquors obtained by leaching copper ores with sulphuric acid.
It is well known to extract copper by hydrometallurgical techniques involving the leaching of copper ores with sulphuric acid to provide a liquor containing cupric sulphate from which copper in metallic form can be recovered. In particular, the copper can be recovered by electrolytic techniques, and it has also been proposed to precipitate copper by saturating the cupriz sulphate solution with sulphur dioxide and heating the saturated solution under conditions of elevated temperature and pressure. These techniques do, however, have disadvantages. Thus the electrolytic techniques are expensive in terms of power consumption and manpower, whereas ~ome hydrometallurgical methods have not been able economically to produce metallic copper with high yields.
The present invention provides a process for extracting copper in a highly efficient manner, both quantitatively and economically, in a manner which has not been possible with methods proposed hitherto.
According to the present invention, copper is extracted from copper-containing materials, for example ores, roasted concentrates, scrap material~ or flue dusts recovered from copper smelting, by leaching in a first stage such materials with sulphuric acid to produce a cupric-sulphate containing liquor, treating such liquor with sulphur dioxide preferably at ~k, .. . ~
~1538~6i substantially atmospheric pressure while maintaining the pH
of the liquor at a level above l, preferably between l and 3, in order to precipitate Chevreul's salt, and in a second stage heating the Chevreul's salt in the presence of water, or water and sulphur dioxide, or sulphurous acid, and under pressure and optionally in the presence of a suitable modify-ing agent to yield metallic copper and suphuric acid.
By "modifying agent" is meant an agent which is designed to increase the yield of copper and/or to modify the form of the copper in order to prevent the copper adhering to the surfaces of the reaction vessels. Suitable second stage modifying agents include magnesium oxide, magnesium carbonate, sodium sulphate, sodium hydroxide, magnesium hydroxide and magnesium sulphate. The preferred agent is magnesium oxide.
In the first stage of the process of the present invention, as Chevreul's salt is precipitated the pH of the reactant solution tends to fall as a result of the reaction:
3 CuSO4 + 3 SO2 + 6H2 -~cu2so3-cuso3-2H2o ~ 4SO4- + 8H+
As the pH falls the precipitation of Chevreul's salt diminishes. This tendency can be reduced, i.e. the pH fall restrained by the addition of a suitable agent to control the pH or by recycling the remaining acidic liquor through a copper-containing ore or other material to leach out further copper. However, in the latter method, a point is reached where the copper content of the leach liquor reaches saturation so that no further copper can be leached out.
At this point it becomes desirable to add a suitable agent " 11531~6 to control the pH so as to precipitate the remaining copper as Chevreul's salt.
According to the present invention suitable first-stage modifying agents include sulphate-containing agents such as sodium sulphate or magnesium sulphate, or alkaline oxides or hydroxides such as sodium hydroxide, magnesium oxide, magnesium carbonate or magnesium hydroxide. The preferred agent is magnesium oxide or magnesium hydroxide. setween l.00 and 1.25 equivalents of magnesium oxide are preferred.
It is important that the pH controlling agent should produce a soluble by-product to avoid contamination of the precipitated Chevreul's salt - calcium oxide for example would be unsuitable for this reason and also because of the problems in disposing of the insoluble gypsum which would be formed. Magnesium oxide has been found particularly suitable as an economical control agent, and moreover the magnesium sulphate formed during the process is a valuable by-product which can contri-bute to the overall economic viability of the process of the invention.
By controlling the pH by the regulation of addition of sulphur dioxide and a modifying agent it is possible to precipitate substantially the whole of the copper from the liquor in the form of Chevreul's salt.
The first stage is desirably conducted at a temperature between 25 and 100C, preferably between 70 and 100C, and particularly between 90 and 95C. The p~ of the liquor is preferably maintained between about 2.08 and 3 during the first stage.
- In the second stage the Chevreul's salt is heated under conditions of elevated temperature and pressure to yield metallic copper and sulphuric acid:
.
~; B
., Cu2SO3.CuSO3.2H2O ~3Cu + 2H2SO4 The copper is recovered in pure form and the sulphuric acid can be recycled for leaching further ore.
The Chevreul's salt may be heated in an autoclave, preferably to a temperature between 100C and 170C, and particularly to a temperature in the vicinity of 150C.
Towards the upper part of the range colloidal sulphur is formed which contaminates the-copper. On the other hand, at temperatures below 150C the reaction rate tends to drop to a level which would eventually become uneconomic.
The pressure is not critical and is in any case determined by the operating temperature. Generally, the operating pressure will be within the range 160 - 200 p.s.i.
Although if Chevreul's salt is heated alone it would produce sulphur dioxide, it is preferred to conduct the autoclaving in the presence of added sulphur dioxide, either as such or in the form of sulphurous acid. The addition of a modifying agent may also be desirable.
The process according to the invention permits the precipitation of copper substantially quantitatively from leach liquors in the form of Chevreul's salt, and subsequently the recovery of metallic copper from the Chevreul's salt in a yield of substantially 100%. Such recoveries have not been possible using methods proposed hitherto.
As stated above, the process of the present invention permits the substantially complete recovery of copper from leach liquors with simultaneous production of sulphuric acid which is available for further leaching. This renders the process highly attractive economically having regard to the cost of transporting sulphuric acid to the usually remote sites where copper ore is mined, and also the current price of copper which makes the substantially 100% recovery permitted by the invention economically most attractive.
One embodiment of the process of the invention is described with particular reference to Figure 1 in which is illustrated a flow diagram schematically representing the steps of the process.
In Figure 1 sulphuric acid is sprayed onto an ore dump and copper sulphate-containing leach liquor is removed and pumped to an intermediate storage point. From there the liquor is pumped to a solvent extraction plant in which ferrous sulphate is removed and pumped to a barren liquor point in which it is bacterially converted to the ferric lS state and then returned to the ore dump with fresh sulphuric acid.
~, The concentrated copper containing liquor is pumped via intermediate storage to a reaction vessel to which is also supplied magnesium oxide for pH control, and sulphur dioxide which would be readily available from smelters associated with ore deposits. The magnesium oxide flow is controlled to provide a pH b~tween 1 and 3 within the reaction vessel.
Chevreul's salt is produced in the reaction vessel and is then transferred to a pressure vessel and heated at approximately 150C in the ~resence of sulphur dioxide and magnesium oxide to produce metallic copper and sulphuric acid which are separated in a filter, the copper being dried and recovered in a high degree of purity, the sulphuric acid 38~6 being returned to storage.
An alternative embodiment of the invention is illustrated in -the flowsheet of Figure 2, which schematically represents the steps of the process for the recovery of copper from S sulphide concentrates which are initially subjected to a fluid bed oxide roast.
It is preferred to operate the process of the invention in two separate stages, the first stage at atmospheric pressure and the second stage at elevated pressure, with separation of the liquor from the Chevreul's salt before the latter is heated in the second stage. It is however, possible to operate the two stages at elevated pressure without separation of the Chevreul's salt from the liquor between stages. It is however, important to adjust the pH appropriately if substantially quantitative yields of Chevreul's salt are to be obtained pr or to autoclaving.
1153~
The invention is described with particular reference to the following examples which are illustrative only.
FORMATION OF CHEVREUL'S SALT
3CuSO + 3SO2 + 6H2O _ ~ Cu2SO3.CuSO3.2H2O + 4SO4 + 8H
A solution of CuSO4.5 H20 (24.97 g in 500 ml, 0.2M or 1.27% Cu) was heated to 90C and SO2 was passed through for 30 minutes. A small amount only of Chevreul's salt was formed (Yield 15~).
A solution of NaOH (70 ml of 4M, 0.28 moles i.e. 1.05 times the H calculated to be formed on a 100% yield of Chevreul's salt) was added over a period of 20 mins. The mixture was cooled in ice to 5C and filtered, the solid being washed with water and then with acetone.
The yield of Chevreul's salt was 12.0 g (93%).
Magnesium Oxide Optimisation Study A solution of CUSO4. 5H2O (39.29 g in 500 ml or 2%Cu3 was heated to 90C and sparged with SO2. The magnesium oxide was added while the solution wàs vigorously stirred.
Stirring was continued with SO2 sparging for 30 minutes.
The reaction mixture was then cooled and Chevreul's salt isoleted and dried. See Table l for results.
.
.:
` ` ~
11538'36, In the following table "one equivalent of MgO" is defined as the amount of MgO needed to neutralise the acid formed upon a 100% yield of Chevreul'~ salt being obtained.
i,e. if x g/l Cu2 initially, then one equivalent of MgO is x x - x 231 = 0.846 x g/l MgO.
63.55 3 Initial Cu concentration 2%
Equivalent of MgO added % depletion of Cu 0.0 15 0.5 56 1.0 92 1.25 97.2
2~
~15~
Chevreul's Salt Formation with Pre-Dissolved Magnesium Oxide Magnesium oxide in an amount of 10.58 grams was suspended in 300 ml of water, preheated to the required temperature, and sulphur dioxide gas, SO2, bubbled through the suspension at approximately 500 ml/min until complete dissolution of the MgO. The SO2 gas was stopped, and 200 ml solution-containing 39.29 grams of copper sulphate, preheated to the required temperature then added to the reaction vessel.
The total reaction time was 30 minutes.
' TABLE 2 Initial Pre- Final pH % Copper Temp. cipitation of Soln Yield Depletion (C) (from Time of (At Reac- (g salt) (Final) Cu Soln addn) Temp.) 7 min 1.99 5.5 31.5 30 sec 1.89 13.2 67.5 15 sec 2.08 17.8 88.0 Inst. Pre- 2.80 19.4 97.5 cipitation .
,~
~ ' .
:: ' --10--.
$
:
~3~
Formation of Chevreul's Salt Using Magnesite, (MgCO3) .
22.11 gm MgCO3 (equivalent to 1.25 equivalents based on 2%
Cu) were suspended in 300 ml of water and the suspension heated to 90C with stirring in the reaction vessel. At 90C, SO2 gas was introduced and suspension dissolved completely after 10~ minutes. 200 ml copper sulphate solution containing 39.29 g CuSO4 5~2 (= 2~ Cu) preheated to 90C was then added to the dissolved magnesite solution with the SO2 still bubbling through. The solution in quick succession changed from blue to yellow, dark brown and reddish-brown and precipitation occurred almost immediately.
The reaction was allowed to proceed for 45 minutes with SO2 bubbling through the solution.
The final filtrate was colourless.
pH of the cooled supernatant solution = 1.95 The weight of Chevreul's Salt obtained = 19.23 gm.
Based on the initial concentration of copper, the yield (copper depletion) was 96.3~.
11538~
DECOMPOSITION OF CHEVREUL'S SALT
50 g Chevreul's salt + reagent (Table 3 below) + water to 500 ml were placed in an autoclave vessel which was then placed in a preheated furnace and stirring started. When the reactor temperature reached 100C (about 5 min~) the heater was turned to low heat. The temperature reached 150 in about another 5-10 minutes.
After 1 hour the reactor was removed from the heater and quickly cooled by passing water through condenser coils.
On opening, the contents were carefully filtered and washed and the filtrate then boiled for l hour and allowed to cool then made up to l litre.
`~ 15 Acid determination: a 10ml aliquot was titrated against 0.lM NaOH vs. methyl orange.
Cu determination: at least two dilutions were made and analysed on the Atomic Absorption Spectrophotometer at 324.7nm.
. .
' .. , .
,.
~538~6 Results:
.
Reagent * Cu yield ** Acid yield (%)***
based on based on actual equation Cu yield and 1 accounting for 2 step mechanism 500 ml water only 83 56 75 SO moles S2 ( 2 = 2) 90 74 87 Chev . _ Chev .
SO
SO ( 2 = 2)+MgO(M~ = 0.5) 92 64 73 2 Chev Chev -S2 ( - = 2)+MgO(MgO = 1) 95 55 59 Chev Chev _ * Chev = Chevreul's salt and molar ratios of reagent to Chevreul's salt are shown in parentheses ** Equation 1: CU2so3.cuso3-2H2o 3Cu+4H + 2SO4 *** yield based on 2 steps Cu2SO3. CuSO3. 2H20 Cu + 2CuSO3 + 2H20 2 3 2 2Cu+2SO4 + 4H
and assuming the first step goes to completion and the second step to the extent of (actual Cu yield - 33.3%).
~15~
Chevreul's Salt Formation with Pre-Dissolved Magnesium Oxide Magnesium oxide in an amount of 10.58 grams was suspended in 300 ml of water, preheated to the required temperature, and sulphur dioxide gas, SO2, bubbled through the suspension at approximately 500 ml/min until complete dissolution of the MgO. The SO2 gas was stopped, and 200 ml solution-containing 39.29 grams of copper sulphate, preheated to the required temperature then added to the reaction vessel.
The total reaction time was 30 minutes.
' TABLE 2 Initial Pre- Final pH % Copper Temp. cipitation of Soln Yield Depletion (C) (from Time of (At Reac- (g salt) (Final) Cu Soln addn) Temp.) 7 min 1.99 5.5 31.5 30 sec 1.89 13.2 67.5 15 sec 2.08 17.8 88.0 Inst. Pre- 2.80 19.4 97.5 cipitation .
,~
~ ' .
:: ' --10--.
$
:
~3~
Formation of Chevreul's Salt Using Magnesite, (MgCO3) .
22.11 gm MgCO3 (equivalent to 1.25 equivalents based on 2%
Cu) were suspended in 300 ml of water and the suspension heated to 90C with stirring in the reaction vessel. At 90C, SO2 gas was introduced and suspension dissolved completely after 10~ minutes. 200 ml copper sulphate solution containing 39.29 g CuSO4 5~2 (= 2~ Cu) preheated to 90C was then added to the dissolved magnesite solution with the SO2 still bubbling through. The solution in quick succession changed from blue to yellow, dark brown and reddish-brown and precipitation occurred almost immediately.
The reaction was allowed to proceed for 45 minutes with SO2 bubbling through the solution.
The final filtrate was colourless.
pH of the cooled supernatant solution = 1.95 The weight of Chevreul's Salt obtained = 19.23 gm.
Based on the initial concentration of copper, the yield (copper depletion) was 96.3~.
11538~
DECOMPOSITION OF CHEVREUL'S SALT
50 g Chevreul's salt + reagent (Table 3 below) + water to 500 ml were placed in an autoclave vessel which was then placed in a preheated furnace and stirring started. When the reactor temperature reached 100C (about 5 min~) the heater was turned to low heat. The temperature reached 150 in about another 5-10 minutes.
After 1 hour the reactor was removed from the heater and quickly cooled by passing water through condenser coils.
On opening, the contents were carefully filtered and washed and the filtrate then boiled for l hour and allowed to cool then made up to l litre.
`~ 15 Acid determination: a 10ml aliquot was titrated against 0.lM NaOH vs. methyl orange.
Cu determination: at least two dilutions were made and analysed on the Atomic Absorption Spectrophotometer at 324.7nm.
. .
' .. , .
,.
~538~6 Results:
.
Reagent * Cu yield ** Acid yield (%)***
based on based on actual equation Cu yield and 1 accounting for 2 step mechanism 500 ml water only 83 56 75 SO moles S2 ( 2 = 2) 90 74 87 Chev . _ Chev .
SO
SO ( 2 = 2)+MgO(M~ = 0.5) 92 64 73 2 Chev Chev -S2 ( - = 2)+MgO(MgO = 1) 95 55 59 Chev Chev _ * Chev = Chevreul's salt and molar ratios of reagent to Chevreul's salt are shown in parentheses ** Equation 1: CU2so3.cuso3-2H2o 3Cu+4H + 2SO4 *** yield based on 2 steps Cu2SO3. CuSO3. 2H20 Cu + 2CuSO3 + 2H20 2 3 2 2Cu+2SO4 + 4H
and assuming the first step goes to completion and the second step to the extent of (actual Cu yield - 33.3%).
Claims (16)
1. A process for extracting copper from copper-containing materials comprising leaching in a first stage such materials with sulphuric acid to produce a cupric sulphate containing liquor, in a first stage treating such liquor with sulphur dioxide while main-taining the pH of the liquor at a level above about 1 in order to precipitate Chevreul's salt; and in a second stage heating the Chevreul's salt in the presence of water, or water and sulphur dioxide, or sulphurous acid, under pressure to yield metallic copper and sulphuric acid.
2. A process according to Claim 1 wherein the first stage is carried out at substantially atmospheric pressure.
3. A process according to Claim 1 wherein the liquor is treated with sulphur dioxide in the presence of a first-stage modifying agent.
4. A process according to Claim 2 wherein the liquor is treated with sulphur dioxide in the presence of a first-stage modifying agent.
5. A process according to Claim 1, 2 or 3 wherein the pH of the liquor is between about 1 and about 3.
- Page 1 of Claims -
- Page 1 of Claims -
6. A process for extracting copper from copper-containing materials comprising leaching in a first stage such materials with sulphuric acid to produce a cupric sulphate containing liquor, in a first stage treating such liquor with sulphur dioxide at substan-tially atmospheric pressure in the presence of a first-stage modifying agent so as to maintain the pH of the liquor between about 1 and about 3, in order to precipi-tate Chevreul's salt; and in a second stage heating the Chevreul's salt in the presence of water, or water and sulphur dioxide, or sulphurous acid, under pressure to yield metallic copper and sulphuric acid.
7. A process according to Claim 6 wherein the Chevreul's salt is separated from the liquor before being transferred to the second stage.
8. A process according to Claim 6 or 7 wherein the first-stage modifying agent is an oxide or hydroxide which forms a soluble product on reaction with the leach liquor.
9. A process according to Claim 6 or 7 wherein the first-stage modifying agent is selected from the group consisting of magnesium oxide, magnesium hydroxide, magnesium carbonate and sodium hydroxide.
10. A process according to Claim 6 or 7 wherein the acid leach liquor is recycled through the copper-containing material to leach out copper, and a - Page 2 of Claims -first-stage modifying agent selected from magnesium oxide, magnesium hydroxide, magnesium carbonate and sodium hydroxide is added when the solubility limit of copper sulphate is reached.
11. A process according to Claim 6 wherein the acid leached liquor from the second stage is separated from metallic copper before being recycled for further leaching of copper from such copper-containing materials.
12. A process according to Claim 6 wherein the second stage is carried out in the presence of a second-stage modifying agent selected from the group consisting of magnesium sulphate, sodium hydroxide, magnesium oxide, magnesium carbonate and magnesium hydroxide.
13. A process according to Claim 6 wherein the first stage is conducted at a temperature between about 70°C and about 100°C.
14. A process according to Claim 6 wherein the second stage is conducted at a temperature between about 100°C and about 170°C.
15. A process according to Claim 6 wherein the pH
of the liquor is maintained between 2.08 and 3 during the first stage.
- Page 3 of Claims -
of the liquor is maintained between 2.08 and 3 during the first stage.
- Page 3 of Claims -
16. A process according to claim 6 wherein 1.00 to 1.25 equivalents of magnesium oxide are employed as the first-stage modifying agent.
- Page 4 of Claims -
- Page 4 of Claims -
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPD7555 | 1979-02-05 | ||
| AUPD755579 | 1979-02-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1153896A true CA1153896A (en) | 1983-09-20 |
Family
ID=3767943
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000344888A Expired CA1153896A (en) | 1979-02-05 | 1980-02-01 | Process for recovering copper |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS55115932A (en) |
| CA (1) | CA1153896A (en) |
| PH (1) | PH15658A (en) |
| ZA (1) | ZA80556B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CZ306037B6 (en) * | 2015-04-30 | 2016-07-07 | Mendelova Univerzita V Brně | Process for preparing cupric-cuprous sulfite dihydrate |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113088982A (en) * | 2021-04-01 | 2021-07-09 | 江西中晟金属有限公司 | Production method of glossy copper rod |
-
1980
- 1980-01-28 PH PH23563A patent/PH15658A/en unknown
- 1980-01-30 ZA ZA00800556A patent/ZA80556B/en unknown
- 1980-02-01 CA CA000344888A patent/CA1153896A/en not_active Expired
- 1980-02-04 JP JP1234480A patent/JPS55115932A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CZ306037B6 (en) * | 2015-04-30 | 2016-07-07 | Mendelova Univerzita V Brně | Process for preparing cupric-cuprous sulfite dihydrate |
Also Published As
| Publication number | Publication date |
|---|---|
| ZA80556B (en) | 1981-02-25 |
| PH15658A (en) | 1983-03-11 |
| JPS55115932A (en) | 1980-09-06 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |