Title of Invention

"AN IMPROVED PROCESS FOR THE EXTRACTION OF COPPER NICKEL AND COBALT FROM POLYMETALLIC SEA NODULES USING COKE OVEN GAS AS PRODUCTANT"

Abstract An improved process for the extraction of copper, nickel and cobalt from polymetallic sea nodules using coke oven gas as reluctant which comprises of grinding the sea nodules characterized in that grinding the sea nodules to 0.1 to 0.5 mm (-35 to 100 mesh) size, drying and calcining such as herein described, under fluidized condition using air as the fluidizing medium at a velocity of 140 to 170 m/h at a temperature of 550 to 750°C for 1 to 2 hours, subjecting to roast reduction at same temperature for 15 to 90 minutes by passing coke oven gas along with air wherein the ratio of the said coke oven gas and air ranges from 1:2 to 2:1, to obtain reduced nodules, cooling under inert atmosphere such as herein described and extracting Cu, Ni, Co by conventional known leaching techniques
Full Text This invention relates to an improved process for the production of copper, nickel, cobalt and other metallic values from polymetallic sea nodules using coke oven gas as reductant. The invention particularly relates to the development of an improved fluidised bed roasting process for this purpose.
This invention will be useful towards the improvement of the existing reduction roasting process for the extraction of metallic values from manganese nodules using the reduction roast - ammonia leach process and is likely to be more economical.
Polymetallic sea nodules comprise mainly of complex oxide and hydroxide phases of manganese and iron and some amounts of silica, aluminia, magnesium and calcium hydroxides etc. The copper and nickel values are intimately associated with the manganese phases (todorokite, birnessite and d-Mn02) whereas cobalt is associated with both the manganese and iron phases (goethite) (Reference may be made to D.W.Fuerstenau and KN.Han, 1983, Mineral Processing and Technology Review, 1 -83). The objective of reduction roasting in the processing of manganese nodules is two fold: i) to liberate Cu, Ni and Co associated with the complex iron and manganese phases and ii) to selectively reduce the oxide phases of Cu, Ni and Co to elemental form to make them amenable to leaching. The iron and manganese phases are reduced up to FeO and MnO respectively.
Various solid, liquid and gaseous reductants have earlier been tried for the reduction roasting of sea nodules and documented in the literature. Solid reductants include the use of charcoal, coal, coke, lignite and sewage sludge (Reference may be made to T.C.Wilder, 1973, U.S.Patent No. 3736125 TC.Wilder, J.J.Andreola and W.E.Galin, 1981, Journal of Metals, 3, 64-69 AKSaha, Z.H.Khan and D.D.Akerkar, 1993, Transactions of Indian Institute of Metals, 46, 63-69; AKSaha, Z.H.Khan and D.D.Akerkar, 1991, Transactions of the Indian Institute of Metals, 44, 131-137; P.Halbach, KKoch, H.J.Renner and KH.Ujma, 1977, Erzmetall., 3, 458-464). In general, with the use of solid reductants, roasting temperatures are higher because of lower diffusivities of solids, selective reduction is more difficult and metal recoveries are lower.
The use of various liquid fuel oils as reductant in the roasting of sea nodules has also been reported (Reference may be made to T.C.Wilder, J.J.Andreola and W.E.Galin, 1981, Journal of Metals, 64-69; AKSaha and D.D.Akerkar, NML Technical Journal, 29, 3-8; T.C.Alex, S.Srikanth, R.KJana, AM.Pande and Premchand, Nov 1995, 49th Annual Technical Meeting of the Indian Institute of Metals, Calcutta). Although liquid reductants yield better results than solid reductants in terms of overall extraction and selectivity of reduction because of their intimate mixing with the charge and subsequent vapourisation, their degree of utilisation is poor because of the vapourisation of oil at lower temperatures and the control of reduction is difficult. Further, with the use of both
solid and liquid reductants, for roasting in a shaft reactor, the charge has to be prepared in pellet form to ensure homogeneous mixing and sufficient strength.
The R&D studies carried out on pilot scale at National Metallurgical Laboratory, Jamshedpur, India (NML) at present involves reduction roasting of 6-9 mm dried pellets premixed with 10% fuel oil as reductant in an electrically heated Vertical Retort Furnace (VRF) (Reference may be made to S.Srikanth, T.C.Alex, M.S.Mahanty, AMPande, ZH.Khan and Premchand, 1996, Proceedings of the Technical Meeting on Research Activities on Polymetallic Sea Nodules, April 1996, RRL Bhubhaneshwar). The roasted pellets is subsequently wet ground and leached in an ammonia-ammonium carbonate medium for the dissolution of copper, nickel and cobalt as ammonium complexes (Reference may be made to R KJana, B.D.Pandey and Premchand Indian Patent application No. 184105 dated 14/8/91; and R.KJana, O.S.R.Murthy, AKNayak, M.S.Mahanty, S.KTiwary and D.D.Akerkar, 1990, International Journal of Mineral Processing 30: 127-141)
The use of a liquid reductant and a shaft reactor in the known process has the following disadvantages:
a) The need for expensive material preparation steps such as pelletisation and drying before charging the material into the roaster. The reduced product has also to be subsequently reground before ammonia leaching.
b) Retarded kinetics of roasting because of lesser surface area of contact and lower diffusivities and consequently poor heat and mass transfer and higher reduction times.
c) Poor utilisation of the reductant. More than 60% of the fuel oil evaporates before 300°C, resulting in oil losses and the non-availability of reductant at elevated temperatures where reduction actually occurs. Use of excess oil also adds up significantly to the cost of the process.
d) Difficulty in the control of oxygen potential inside the reactor and consequently difficulty in selective reduction.
e) Non-uniformity of temperature along the radial direction in an externally heated shaft furnace results in non- uniform reduction of the pellets.
f) The recovery of cobalt which is crucial to the commercial success of the process seldom exceeds 65% with the use of liquid reductant at pilot scale operations.
Gaseous reductants may be expected to perform better than solid and liquid reductants in terms of control of oxygen potential, degree of reduction, enhanced kinetics of reduction and degree of utilisation. Various gases such as carbon monoxide, hydrogen and liquified petroleum gas with carbon dioxide, water vapour and nitrogen in varying proportions have been used for the reduction roasting of sea nodules and reported in the literature. Brooks and coworkers (PT.Brooks, KC.Dean and J.B.Rosenbaum, 1970, Proceedings International
Mineral Congress, Czechoslovakia, 329-333; P.T.Brooks and DAMartin, 1971 U.S.Bureau of Mines Report of Investigation 7473;) carried out reduction roasting of sea nodules at 600°C with a gas mixture of CO+CO2+H2+N2 containing 8% H2 and 8% CO and achieved leach recoveries of 90% for Ni and Cu and 70% for Co Kennecott Copper Corporation holds at least two patents on the reduction roasting of manganese nodules using CO-C02 mixtures followed by ammonia/ammonium salt leaching (Reference may be made to T.C Wilder and J.J.Andreola, 1973, US Patent No. 3753686; J.C.Agrawal and T.C.Wilder, 1974, US Patent No 3788841;) Redman (M.J.Redman, 1972, German Patent No. 2135734; M.J.Redman, 1973, US Patent No. 3734715;) studied the reduction behaviour of manganese nodules as a function of roasting time, temperature and gas composition using a CO+CO2+H2+N2 gas mixture. Sridhar and coworkers (R.Sridhar, W.E.Jones and J S.Warner, 1976, Journal of Metals, 32-37;) carried out reduction roasting at 1000°C for 105 minutes using a gas analysing 8.7% H2, 6.7% H20, 14.7% CO, 6 7% C02 and 63.2% N2 followed by smelting to yield more than 90% recovery of Cu, Ni and Co. Drakshayani et al (D.N.Drakshayani, C.Sankar and R.M.Mallya, 1989, Thermochimica Acta, 144, 313-328;) have carried out reduction roasting of manganese nodules using pure hydrogen. Han and coworkers (K.N.Han, M.Hoover and D.W. Fuerstenau, 1974, International Journal of Mineral Processing, 1, 215- 230;) have conducted experiments on the reduction roasting of Pacific Ocean nodules at 400 and 600°C for 2 hours using a gas mixture with a CO/CO2 ratio of 1.5 followed by ammonia leaching. National Metallurgical Laboratory, India has earlier taken a patent on the reduction roasting of sea
nodule powders using liquified petroleum gas (D.Jha, Sanjay Prasad and Premchand, Indian Patent Application No. 185815. dated 11.11.92)
From a thermodynamic point of view, hydrogen is a more effective reductant at lower temperatures. The use of coke oven gas which is a by product in an integrated steel plant and is enriched in hydrogen has not been so far tested for the reduction roasting of sea nodules. When available, coke oven gas is much cheaper compared to pure hydrogen, carbon monoxide or liquid petroleum gas. Several integrated steel plants are expected to be set up in the eastern coast of India such as in Gopalpur. It would be logical to expect any commercial plant for the production of metals from sea nodules in India to be located in close proximity to the steel plants. It would therefore be worthwhile to explore the use of coke oven gas as a reductant for polymetallic sea nodules.
The main object of the present invention is to provide an improved process for the extraction of metallic values such as copper, nickel and cobalt from deep sea manganese nodules using coke oven gas as reductant and thereby reducing cost of production.
In the present invention, polymetallic sea nodules in powder form is roast reduced in an electrically heated Fluidized Bed Reactor (FBR) using a mixture of coke oven gas and air both as fluidizing medium and as reductant.
In a fluidized bed reactor, when a stream of gas passes upward through a packed bed of finely divided solid particles of unrestrained upper surface, the bed
expands and the pressure drop across the bed increases as a function of gas velocity until the drag on the individual particles exceeds the force exerted by gravity i.e., the pressure drop across the bed equals the weight of the bed per unit area Thereafter, fluidisation occurs, wherein, the pressure drop is independent of the gas velocity. During fluidisation, the interpartide friction is so small that the fluid/solid assembly behaves like a liquid having a density equal to the bulk density of the powder. The velocity at which the pressure drop becomes independent is termed as the theoretical minimum fluidisation velocity which is a function of partide size and density of the solid powder and density and fluidity of the fluidising gas. Characteristics of good fluidisation are good solid mixing, uniform bed expansion and deaeration rate.
Coke oven gas is a by-product of an integrated steel plant and has the
following average composition:
CO 7 %
C02 2.6 %
CH4 28 %
C2H4 3 %
H2 56 %
N2 2.8 %
O2 0.4 %
Specific gravity = 0.4.
The following general reactions are expected to take place during fluidized bed roasting of sea nodules using coke oven gas:
CH4→C + 2H2 (1)
C2H4 → 2C + 2H2 (2)
2C + 02→ 2CO (3)
CuO + H2 → Cu + H20 (4)
NiO + H2 → Ni + H20 (5)
CoO + H2 → Co + H20 (6)
3Fe203 + H2 → 2Fe304 + H20 (7)
Fe304 + H2 →3FeO + H20 (8)
3Mn203 + H2 → 2Mrb04 + H20 (9)
Mn304 + H2 → 3MnO + H20 (10)
CuO + CO→ Cu + C02 (11)
NiO + CO→ Ni + C02 (12)
CoO + CO→ Co + C02 (13)
3Fe203 + CO → 2Fe304 + C02 (14)
Fe304 + CO → 3FeO + C02 (15)
FeO + CO→ Fe + C02 (16)
3Mn203 + CO→ 2Mn304 + C02 (17)
Mn304 + CO → 3MnO + C02 (18)
The hydro-carbons present in the coke oven gas such as CH4 and C2H4 will decompose to hydrogen gas and carbon (Eqs. 1 and 2). The hydrogen of the coke
Oven gas is expected to reduce the higher oxides of iron and manganese as well as partially reduce the copper, nickel and cobalt oxides (Eqs. 3 to 10). The carbon generated through the dissociation of the hydrocarbons will combine with the oxygen of the charge to form CO (eq. 3). The carbon monoxide generated by the hydrocarbons as well as that already present in the coke oven gas will also partake in the reduction of Fe, Mn, Cu, Ni and Co oxides (Eqs. 11 to 18). Reduction by hydrogen will predominate at lower temperatures ( Accordingly, the present invention provides an improved process for the extraction of copper, nickel and cobalt from polymetallic sea nodules using coke oven gas as reluctant which comprises of grinding the sea nodules characterized in that grinding the sea nodules to 0.1 to 0.5 mm (-35 to 100 mesh) size, drying and calcining such as herein described, under fluidized condition using air as the fluidizing medium at a velocity of 140 to 170 m/h at a temperature of 550 to 750°C for 1 to 2 hours, subjecting to roast reduction at same temperature for 15 to 90 minutes by passing coke oven gas along with air wherein the ratio of the said coke oven gas and air ranges from 1:2 to 2:1, to obtain reduced nodules, cooling under inert atmosphere such as herein described and extracting Cu, Ni, Co by conventional known leaching techniques.
The copper and nickel can then be recovered from the leach solution by known processes such as solvent extraction with an organic such as LIX 64N or 84N (propriety reagent of HENKEL Corporation, USA) wherein, the copper and nickel are selectively loaded to the organic phase leaving the cobalt in the aqueous phase. Subsequently, the copper and nickel are selectively stripped as
sulphates using sulphuric acid of varying concentrations and copper and nickel recovered from the sulphate solution by electrowinning. The cobalt is recovered as cobalt oxide after steam stripping of ammonia and calcination of the resultant cobalt carbonate.
According to the features of this invention, the sea nodutes selected may
have the following composition range:
Cu 0.6-1.2%
Ni 0.7-1.5%
Co 0.08 - 0.5 %
Fe 7-15%
Mn 15-25%
Zn 0.06-0.1%
Mo 0.02 - 0.05 % Si02 15-20% Al203 2-5% Free Moisture -10 -15 % Loss of Ignition at 900°C - 25 - 30 %
Inert gas used for cooling the roasted sea nodules in the fluidised bed reactor may be nitrogen or argon. The dilute ammoniacal solution used for quenching the reduced sea nodules may have a concentration in the range of 40 to 75 gpl NH3 and 30 to 60 gpl CQ2. Strong ammoniacal solution used for preconditioning of the quenched product may have a concentration in the range of
140 to 200 gpl ammonia and 80 to 200 gpl C02 and carried out at a solid to liquid ratio in the range of 1.5 to 2.5. In the first stage of leaching, the leachant may have a concentration in the range of 90 to 120 gpl NH3 and 55 to 65 gpl C02 and carried out at an air flow rate lying in the range of 1.2 to 1.5 m3/h at a solid to liquid ratio of 1:10 for periods lying in the range of 30 to 120 minutes at ambient temperature and pressure. In the second stage of leaching, the lixiviant may have a concentration in the range of 90 to 120 gpl ammonia and 50 to 60 gpl carbon dioxide and carried out at an air flow rate lying in the range of 2.0 to 3.0 m3/h at a solid to liquid ratio of 1:7 for periods lying in the range of 120 to 180 minutes at ambient temperature and pressure. Ammonia solution used for washing of the leach residue after the second stage of leaching may have concentration in, the range of 40 to 60 gpl NH3 and 30 to 40 gpl CO2.
By the process of present invention, coke oven gas has been used as the reductant for the roasting of sea nodules. With a subsequent ammonia leaching of the roasted product, leach recoveries up to 90% copper, 98% nickel and 80% cobalt have been achieved.
The following examples are given by way of illustration and should not be construed to limit the scope of the invention.
EXAMPLE 1
A sample of 5 kg of ground (-35+100 mesh) sea nodule powder of composition Cu-0.7%, Ni-0.9%, Co-0.13%, Fe-7.4%, Mn-18.3%, Free moisture-16.0% and Combined moisture-13.0% was charged into the Fluidised
Bed Reactor. The temperature of the furnace was raised from ambient temperature to 650°C over a time period of 90 minutes. Air at a velocity of 170 m/h was used as the fluidising medium during heating of the sea nodule powders During this heating period, drying and calcination of the sea nodules take place At 650°C, a mixture of coke oven gas + air was passed through the distributor plate at the bed of the furnace. For this experiment, the ratio of coke oven gas to air was maintained at 0.6 at a fluidisation velocity of 150 m/h. As soon as the gas flow is switched to a mixture of coke oven gas + air, the temperature of the fluidising charge increased by about 45°C to 695°C. After the temperature stabilised, the set temperature of the reactor was changed to 700°C and maintained at this temperature through a controller. The temperature of the charge was measured by a calibrated chromel-alumel thermocouple suspended in the fluidised charge. The reduction was carried out at 700°C for 60 minutes. At the end of the reduction period, the heater was switched off and the gas flow was switched to high purity argon (02 stage leaching was carried out for 40 minutes in an ammonia- ammonium carbonate medium at a concentration of 105 gpl NH3 and 60 gpl C02 and aerated at the rate of 1.4 m3/h. After the first stage of leaching, the solution was filtered, the leach residue dissolved in fresh ammonia solution and the second stage of leaching was started. The second stage leaching was carried out for 2 hours in an ammonia solution of concentration NH3-98 g/l and C02-58 g/l and aerated at the rate of 2 m3/h. At the end of the two hour period, the solution was filtered and the residue was washed with a fresh ammonia solution of concentration NH3-50 gpl and C02-35 gpl. After washing, the residue was dried at 350°C for four hours, weighed and samples taken for metal analysis. Samples of the leach solution at the end of the first stage and second stage of leaching and washing was also taken for metal analysis. The analyses for Cu, Ni and Co was carried out in an Atomic Absorption Spectrophotometer after neccessary calibration. Recovery of copper, nickel and cobalt after leaching was found to be 88 %, 96 % and 79 % respectively on residue basis. On solution basis, the recoveries were found to be 90 % Cu, 98.5 % Ni and 80 % Co.
EXAMPLE 2
A sample of 5 kg of ground (35+100 mesh) sea nodule powder of composition Cu-0.9%, Ni-1.25%, Co-0.09%, Fe-7.0%, Mn-20.3%, Free moisture-17.2% and Combined moisture-12.0% was charged into the Fluidised Bed Reactor. The temperature of the furnace was raised from ambient temperature to 650°C over a time period of 90 minutes. Air at a velocity of 170 m/h
was used as the fluidising medium during heating of the sea nodule powders During this heating period, drying and calcination of the sea nodules take place At 650°C, a mixture of coke oven gas + air was passed through the distributor plate at the bed of the furnace. For this experiment, the ratio of coke oven gas to air was maintained at 0.4 at a fluidisation velocity of 150 m/h. As soon as the gas flow is switched to a mixture of coke oven gas + air, the temperature of the fluidising charge increased by about 45°C to 695°C. After the temperature stabilised, the set temperature of the reactor was changed to 700°C and maintained at this temperature through a controller. The temperature of the charge was measured by a calibrated chromel-alumel thermocouple suspended in the fluidised charge. The reduction was carried out at 700°C for 60 minutes. After the temperature reached 200°C, the supply of traces of coke oven gas was completely shut off and the charge was allowed to cool in argon atmosphere. During the cooling also, the fluidising velocity was maintained at 150 m/h. After cooling to ambient temperature, the reduced product was quenched in dilute ammoniacal solution having a concentration of 50 g/l NH3. The slurry obtained was subjected to preconditioning for 1 hour in an ammonia solution of concentration NH3 150 g/l and C02 85 g/l. The preconditioned slurry was leached in two stages. The first stage leaching was carried out for 40 minutes in an ammonia- ammonium carbonate medium at a concentration of 105 gpl NH3 and 60 gpl C02 and aerated at the rate of 1.4 m3/h. After the first stage of leaching, the solution was filtered, the leach residue dissolved in fresh ammonia solution and the second stage of leaching was started. The second stage leaching was carried out for 2 hours in an
ammonia solution of concentration NH3-98 g/l and C02-58 g/l and aerated at the rate of 2 m3/h. At the end of the two hour period, the solution was filtered and the residue was washed with a fresh ammonia solution of concentration NH3-50 gpl and C02-35 gpl. After washing, the residue was dried at 350°C for four hours, weighed and samples taken for metal analysis. Samples of the leach solution at the end of the first stage and second stage of leaching and washing was also taken for metal analysis. The analyses for Cu, Ni and Co was carried out in an Atomic Absorption Spectrophotometer after neccessary calibration. Recovery of copper, nickel and cobalt after leaching was found to be 88 %, 96 % and 79 % respectively on residue basis. On solution basis, the recoveries were found to be 89 % Cu, 98 % Ni and 60 % Co.
EXAMPLE 3
A sample of 5 kg of ground (-35+100 mesh) sea nodule powder of composition Cu-1.11%, Ni-1.12%, Co-0.096%, Fe-6.88%, Mn-24.2%, Free moisture-16.8% and Combined moisture-13.2% was charged into the Fluidised Bed Reactor. The temperature of the furnace was raised from ambient temperature to 590°C over a time period of 60 minutes. Air at a velocity of 170 m/h was used as the fluidising medium during heating of the sea nodule powders. During this heating period, drying and calcination of the sea nodules take place. At 590°C, a mixture of coke oven gas + air was passed through the distributor plate at the bed of the furnace. For this experiment, the ratio of coke oven gas to air was maintained at 0.67 at a fluidisation velocity of 150 m/h. As soon as the gas flow is
switched to a mixture of coke oven gas + air, the temperature of the fluidising charge increased by about 55°C to 645°C. After the temperature stabilised, the temperature of the reactor was changed to 650°C and maintained at this temperature through a controller. The temperature of the charge was measured by a calibrated chromel-alumel thermocouple suspended in the fluidised charge. The reduction was carried out at 650°C for 55 minutes. After the temperature reached 200°C, the supply of traces of coke oven gas was completely shut off and the charge was allowed to cool in argon atmosphere. During the cooling also, the fluidising velocity was maintained at 150 m/h. After cooling to ambient temperature, the reduced product was quenched in dilute ammoniacal solution having a concentration of 50 g/l NH3. The slurry obtained was subjected to preconditioning for 1 hour in an ammonia solution of concentration NH3 150 g/l and CO2 85 g/l. The preconditioned slurry was leached in two stages. The first stage leaching was carried out for 40 minutes in an ammonia- ammonium carbonate medium at a concentration of 105 gpl NH3 and 60 gpl C02 and aerated at the rate of 1.4 m3/h. After the first stage of leaching, the solution was filtered, the leach residue dissolved in fresh ammonia solution and the second stage of leaching was started. The second stage leaching was carried out for 2 hours in an ammonia solution of concentration NH3-98 g/l and C02-58 g/l and aerated at the rate of 2 m3/h. At the end of the two hour period, the solution was filtered and the residue was washed with a fresh ammonia solution of concentration NH3-50 gpl and C02-35 gpl. After washing, the residue was dried at 350°C for four hours, weighed and samples taken for metal analysis. Samples of the leach solution at
the end of the first stage and second stage of leaching and washing was also taken for metal analysis. The analyses for Cu, Ni and Co was carried out in an Atomic Absorption Spectrophotometer after neccessary calibration. Recovery of copper, nickel and cobalt after leaching was found to be 94.6 %, 94.0 % and 46.8 % respectively on residue basis. On solution basis, the recoveries were found to be 95.7 % Cu, 99.5 % Ni and 45.0 % Co.
The main advantages of the present invention are as follows:
1 Coke oven gas is a cheap by product of an integrated steel plant. The degree of utilisation of coke oven gas during the reduction process is better than fuel oil which has been used thus far. Further, the calorific value of the coke oven gas is partially utilised in heating the charge.
2 Since coke oven gas is a hydrogen enriched gas, it is a more effective reductant than carbon or carbon monoxide at the temperatures of reduction roasting generally adopted for sea nodules.
3. The present invention requires very minimum material preparation. The stages of mixing, drying and pelletising are completely eliminated.
4 Kinetics of reduction in a fluidised bed reactor using gaseous reductants is much superior because of intimate gas- solid mixing compared to that obtained in a vertical retort furnace using fuel oil as reductant. This results in lower times of reduction and consequently higher productivity.
5. The energy efficiency of a fluidised bed reactor is far superior to the Vertical Retort Furnace because of the high heat transfer rate in the FBR Further, the temperature of the charge is uniform and can be controlled to within 2°C unlike in the VRF where temperature gradients exist in the radial direction. Therefore, a consistently reduced roasted product is achieved in a Fluidized Bed Reactor.
6. The oxygen potential prevailing during the reduction using coke oven gas can be accurately controlled by installation of oxygen sensors at the gas outlet. This will enable an accurate control over the reduction and its selectivity.
7 The roasted product obtained in the Fluidized Bed Roasting process can be directly used for subsequent leaching thereby eliminating the intermediate stage of wet grinding being thus far.




We Claim:
1. An improved process for the extraction of copper, nickel and cobalt from polymetallic sea nodules using coke oven gas as reluctant which comprises of grinding the sea nodules characterized in that grinding the sea nodules to 0.1 to 0.5 mm (-35 to 100 mesh) size, drying and calcining such as herein described, under fluidized condition using air as the fluidizing medium at a velocity of 140 to 170 m/h at a temperature of 550 to 750°C for 1 to 2 hours, subjecting to roast reduction at same temperature for 15 to 90 minutes by passing coke oven gas along with air wherein the ratio of the said coke oven gas and air ranges from 1:2 to 2:1, to obtain reduced nodules, cooling under inert atmosphere such as herein described and extracting Cu, Ni, Co by conventional known leaching techniques.
2. An improved process as claimed in Claims 1 wherein the inert gas used for cooling is nitrogen or argon with traces of coke oven gas.
3. An improved process as claimed in claims 1 to 2 wherein the leaching is carried out by using a ammonia - ammonium carbonate solution in a known manner.
4. An improved process for the extraction of copper, nickel and cobalt from polymetallic sea nodules using coke oven gas as reluctant substantly as herein described with described with reference to the examples.

Documents:

63-del-1999-abstract.pdf

63-del-1999-claims.pdf

63-del-1999-correspondence-others.pdf

63-del-1999-correspondence-po.pdf

63-del-1999-description (complete).pdf

63-del-1999-form-1.pdf

63-del-1999-form-19.pdf

63-del-1999-form-2.pdf


Patent Number 242252
Indian Patent Application Number 63/DEL/1999
PG Journal Number 35/2010
Publication Date 27-Aug-2010
Grant Date 19-Aug-2010
Date of Filing 12-Jan-1999
Name of Patentee COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
Applicant Address RAFI MARG, NEW DELHI- 110 001, INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 SRINIVASAN SRIKANTH NATIONAL METALLURGICAL LABORATORY, JAMSHEDPUR, 831007, INIDA.
2 PREMCHAND NATIONAL METALLURGICAL LABORATORY, JAMSHEDPUR, 831007, INIDA.
PCT International Classification Number C22B 15/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA