AU2003249789B2 - Recovering nickel - Google Patents
Recovering nickel Download PDFInfo
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- AU2003249789B2 AU2003249789B2 AU2003249789A AU2003249789A AU2003249789B2 AU 2003249789 B2 AU2003249789 B2 AU 2003249789B2 AU 2003249789 A AU2003249789 A AU 2003249789A AU 2003249789 A AU2003249789 A AU 2003249789A AU 2003249789 B2 AU2003249789 B2 AU 2003249789B2
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- iron
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- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 title claims description 122
- 229910052759 nickel Inorganic materials 0.000 title claims description 54
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 79
- 238000001556 precipitation Methods 0.000 claims description 62
- 238000000034 method Methods 0.000 claims description 38
- 229910052742 iron Inorganic materials 0.000 claims description 34
- 239000010941 cobalt Substances 0.000 claims description 33
- 229910017052 cobalt Inorganic materials 0.000 claims description 33
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 33
- 239000002245 particle Substances 0.000 claims description 27
- 229910052751 metal Inorganic materials 0.000 claims description 19
- 239000002184 metal Substances 0.000 claims description 19
- 238000002386 leaching Methods 0.000 claims description 16
- 239000002253 acid Substances 0.000 claims description 15
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 14
- 239000003638 chemical reducing agent Substances 0.000 claims description 14
- 238000006386 neutralization reaction Methods 0.000 claims description 14
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 claims description 12
- 229910001710 laterite Inorganic materials 0.000 claims description 8
- 239000011504 laterite Substances 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 7
- 238000012545 processing Methods 0.000 claims description 7
- 239000012141 concentrate Substances 0.000 claims description 5
- 229910001447 ferric ion Inorganic materials 0.000 claims description 5
- 229910001448 ferrous ion Inorganic materials 0.000 claims description 5
- 150000002739 metals Chemical class 0.000 claims description 5
- 230000003647 oxidation Effects 0.000 claims description 4
- 238000007254 oxidation reaction Methods 0.000 claims description 4
- 230000001376 precipitating effect Effects 0.000 claims description 4
- 230000001580 bacterial effect Effects 0.000 claims description 3
- 229910001919 chlorite Inorganic materials 0.000 claims description 2
- 229910052619 chlorite group Inorganic materials 0.000 claims description 2
- QBWCMBCROVPCKQ-UHFFFAOYSA-N chlorous acid Chemical compound OCl=O QBWCMBCROVPCKQ-UHFFFAOYSA-N 0.000 claims description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 2
- 239000011707 mineral Substances 0.000 claims description 2
- 230000003472 neutralizing effect Effects 0.000 claims description 2
- 239000000243 solution Substances 0.000 description 27
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 21
- 238000012360 testing method Methods 0.000 description 21
- 239000000047 product Substances 0.000 description 19
- 238000011084 recovery Methods 0.000 description 16
- 239000011651 chromium Substances 0.000 description 14
- 229910052782 aluminium Inorganic materials 0.000 description 12
- 229910052804 chromium Inorganic materials 0.000 description 12
- 238000003556 assay Methods 0.000 description 11
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 10
- 239000004411 aluminium Substances 0.000 description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 10
- 239000011701 zinc Substances 0.000 description 10
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 9
- 239000010949 copper Substances 0.000 description 9
- 229910052802 copper Inorganic materials 0.000 description 9
- 230000000694 effects Effects 0.000 description 8
- 229910052725 zinc Inorganic materials 0.000 description 8
- 229910017709 Ni Co Inorganic materials 0.000 description 7
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 6
- 239000005864 Sulphur Substances 0.000 description 6
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 229910052748 manganese Inorganic materials 0.000 description 5
- 239000011572 manganese Substances 0.000 description 5
- 230000003247 decreasing effect Effects 0.000 description 4
- 229910052749 magnesium Inorganic materials 0.000 description 4
- 239000011777 magnesium Substances 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 229910017518 Cu Zn Inorganic materials 0.000 description 3
- 235000019738 Limestone Nutrition 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000013101 initial test Methods 0.000 description 3
- 239000006028 limestone Substances 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 2
- 238000000975 co-precipitation Methods 0.000 description 2
- 229910052602 gypsum Inorganic materials 0.000 description 2
- 239000010440 gypsum Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 150000004763 sulfides Chemical class 0.000 description 2
- WURBVZBTWMNKQT-UHFFFAOYSA-N 1-(4-chlorophenoxy)-3,3-dimethyl-1-(1,2,4-triazol-1-yl)butan-2-one Chemical compound C1=NC=NN1C(C(=O)C(C)(C)C)OC1=CC=C(Cl)C=C1 WURBVZBTWMNKQT-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 229910009369 Zn Mg Inorganic materials 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical class [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012527 feed solution Substances 0.000 description 1
- 229910052598 goethite Inorganic materials 0.000 description 1
- 229910052595 hematite Inorganic materials 0.000 description 1
- 239000011019 hematite Substances 0.000 description 1
- AEIXRCIKZIZYPM-UHFFFAOYSA-M hydroxy(oxo)iron Chemical compound [O][Fe]O AEIXRCIKZIZYPM-UHFFFAOYSA-M 0.000 description 1
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 1
- 229910052935 jarosite Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- -1 nickel Chemical class 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- HYHCSLBZRBJJCH-UHFFFAOYSA-M sodium hydrosulfide Chemical group [Na+].[SH-] HYHCSLBZRBJJCH-UHFFFAOYSA-M 0.000 description 1
- WWNBZGLDODTKEM-UHFFFAOYSA-N sulfanylidenenickel Chemical class [Ni]=S WWNBZGLDODTKEM-UHFFFAOYSA-N 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 229910021653 sulphate ion Inorganic materials 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 238000010977 unit operation Methods 0.000 description 1
Classifications
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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
Description
WO 2004/016816 PCT/AU2003/001037 RECOVERING NICKEL The present invention relates to a process for recovering valuable metals, such as nickel, from liquors 5 obtained by processing laterite ores and concentrates of the ores that are contaminated with high levels of iron. The term "processing laterite ores and concentrates" is understood herein to include processing 10 by any one or more of heap leaching, pressure leaching, bacterial oxidation leaching, and atmospheric tank leaching. The present invention relates particularly, 15 although by no means exclusively, to a process for recovering nickel and cobalt from liquors obtained by acid leaching ores and concentrates of the ores that are contaminated with high levels of iron. 20 In this context, the term "high levels of iron" is understood to mean levels of iron whereby the mole ratio of Fe:Ni is greater than 2:1. It is known that nickel can be recovered from 25 such liquors containing nickel by contacting the liquors with H 2 S to precipitate nickel sulphides (and mixed sulphides in situations where nickel and other valuable metals such as cobalt are in the liquors). 30 However, it is also known that iron will co precipitate as a sulphide under conventional H 2 S precipitation conditions and that such co-precipitation is undesirable from the viewpoint of'optimising recovery of nickel (and cobalt). 35 It is known that iron can be removed from liquors prior to nickel (and cobalt) precipitation by using (a) - 2 high temperatures (180-220*C) to selectively precipitate iron as hematite (b) low temperatures (90-120*C) to precipitate iron as goethite, and low temperatures (70 150 0 C) to precipitate iron as jarosite. However, high 5 temperature precipitation is capital intensive, requiring autoclaves and flash vessels, and low temperature precipitation results in high nickel losses as a result of nickel adsorption onto iron species. 10 The applicant has developed a process that is capable of recovering very high levels (greater than 99%) of nickel from nickel liquors with very low levels of co precipitation of iron. 15 According to the present invention there is provided a process for recovering a valuable metal in the form of nickel from a leach liquor obtained by processing laterite ores and concentrates that are contaminated with iron by any leaching process including one or more of heap 20 leaching, pressure leaching, bacterial oxidation leaching, and atmospheric tank leaching, the leach liquor containing the valuable metal and iron in solution, which process includes the following steps after the leach process of: 25 (a) processing the leach liquor by reducing ferric ions to ferrous ions in the leach liquor using a suitable gaseous reductant; (b) neutralizing the processed leach liquor to 30 reduce the free acid concentration in solution to levels suitable for nickel precipitation while maintaining iron in the ferrous state; and (a) (c) precipitating the valuable metal using the 35 reductant and seed particles under process conditions, including one or more of seed particle size, seed composition, and N:Melbo umetIases\t .AU.MPecisXAncded pags 2009.5-74oc temperature, that are selected to maximise nickel precipitation and to minimize iron precipitation. 5 Preferably the reduction step (a) includes reducing ferric ions to ferrous ions using the reductant in the presence of an initial concentration of 40-90 g/Il free acid. 10 The reductant may be any suitable reductant. One suitable reductant is NaHS. Preferably the gaseous reductant is H 2 8. 15 Preferably the neutralisation step (b) increases the pH of the solution to 2. Preferably the valuable metals are nickel and 20 cobalt. Preferably the laterite ores are ores that contain nickel in a chlorite mineral phase. 25 Preferably the process conditions for the precipitation step (c) include operating at a partial pressure of the gaseous reductant of less than 60 psi. More preferably the gas partial pressure is less 30 than 40 psi. More preferably the gas partial pressure is less than 30 psi. N:\M4N--AC-APate fW6 999tp4846iAU II\ AMended pqcs 2009
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5 -7,doc WO 2004/016816 PCT/AU2003/001037 -4 It is preferred particularly that the gas partial pressure be less than 25 psi. Preferably the process conditions for the 5 precipitation step (c) include operating at a liquor temperature of at least 50"C. More preferably the liquor temperature is at least 60 0 C. 10 Preferably the seed particles for the precipitation step (c) have a particle size of P 50 less than 100 micron. 15 More preferably the particle size of the seed particles is P 50 less than 80 micron. It is preferred particularly that the particle size of the seed particles be P 50 less than 60 micron. 20 Preferably the seed particle concentration for the precipitation step (c) is greater than 30g/l. More preferably the seed particle concentration 25 is greater than 40g/l. Preferably the ratio of iron and the valuable metal in the leach liquor supplied to step (a) is greater than 2:1. 30 More preferably the ratio is greater than 3:1. More preferably the ratio is greater than 5:1. 35 The present invention is based on extensive experimental work carried out by the applicant to recover nickel and cobalt from laterite ores. The experimental WO 2004/016816 PCT/AU2003/001037 -5 work included the following work. EXPERIMENTAL 5 Initial sulphide precipitation test work using a gaseous reductant in the form of H 2 S gas in the presence of seed particles was carried out on synthetic liquor generated by dissolving technical grade sulphate salts in tap water. 10 The initial test work included test work for optimal precipitation conditions using the synthetic liquor. 15 The initial test work investigated the following precipitation parameters to determine their effect on nickel and cobalt recovery and nickel/iron separation: * Temperature 20 e H 2 S pressure e Seed particle size e Seed concentration, The initial test work for optimal precipitation 25 conditions was conducted under the following conditions: e Agitation = 750 rpm with twin axial turbines * Sampling time = 15, 30 and 60 minutes (in some instances a 120 minute sample was also taken). 30 0 Seed chemistry = synthetic NiS, Ni:S = 0.95 Once the optimal conditions for sulphide precipitation were determined, further tests were conducted using liquors generated from heap leaching of 35 laterite ores from a range of different sources. The different sources are referred to as GA-Ev, GA-Tr, GL-Ka, and GL-Ak in the following description.
WO 2004/016816 PCT/AU2003/001037 -6 The heap leach liquors were spiked with nickel and cobalt sulphate salts to increase the nickel and cobalt concentration in solution to -4 and 0.2 g/l respectively to simulate recycling of liquor to the heap. 5 Analysis of the liquors used in the test work is given in Table 1. Table 1 - Liquor Compositions 10 Lig. Source | Ni Co _Fe M Cr uAl Mn Cu Zn uFA Synthetic 4.04 198 24.9 5.94 526 8.00 706 1 5 1.0 GA-Ev 4.16 204 26.0 4.58 593 4.46 470 5 5 80 GA-Tr 4.02 196 22.6 3.62 749 3.91 511 4 3 86 GA-Ka 4.20 200 16.4 13.4 108 0.272 313 3 73 45 GA-Ak 4.25 210 27.2 4.82 518 4.88 455 3 3 73 Assays are in mg/L D denotes assays in g/L Sulphide product assays were all back calculated 15 to discount the seed component. RESULTS Effect of Temperature on Mixed Sulphide.Precipitation 20 Temperature influences the precipitation process through its influence on H 2 S solubility and the dissociation equilibrium constant for H 2 S. 25 The kinetics of precipitation are also influenced by temperature. The effect of temperature on metal precipitation was determined under the following conditions: 30 Seed P 50 - 109 microns
H
2 S pressure - 30 psi Seed concentration - 30 g/L Residence Time - 60 minutes WO 2004/016816 PCT/AU2003/001037 -7 The detailed results for Tests 1 to 4 from these tests are summarised in Figure 1. 5 The results show that increasing the temperature increased metal precipitation. Metal precipitation increased dramatically between 40 0 C and 60 0 C and there was only a marginal increase in metal precipitation between 80*C and 95*C after 60 minutes. The Ni:Fe mole ratio 10 ranged from 7 to 10 between 60 and 95 0 C and appears to reach a maximum at 80 0 C and then decrease again at 95 0 C. Precipitation of aluminium, magnesium, manganese and chromium were low (<1%) under the conditions 15 investigated. Effect of Seed Charge In commercial operations seed particles are added 20 to facilitate precipitation. It is expected that as the seed surface area increases the kinetics of precipitation increases, thereby resulting in a lower S2- concentration in solution, and enabling better selectivity for nickel and cobalt over iron. 25 The surface area of seed particles can be increased by increasing the mass of seed in the reactor or by seeding with solids with a smaller average particle size. The influence of both factors was investigated. 30 Detailed results are summarised in Figures 2 and 3. The results show that nickel and cobalt recovery increased with the mass of seed added and with a decreasing average seed particle size. Both these 35 observations are consistent with nickel and cobalt recovery increasing with increasing seed surface area.
WO 2004/016816 PCT/AU2003/001037 -8 When the seed particle size was reduced from P 50 = 109 microns to P 5 o = 45 microns nickel recovery increased from 98.2 to 99.5% while cobalt recovery increased from 99.0 to 99.7%. 5 Using the finer seed had little effect on the Ni:Fe mole ratio in the product which appeared to decrease slightly from 7.0 to 6.7. This change in the Ni:Fe ratio is probably not significant within the errors of the 10 experiment. When the seed concentration was increased from 30 to 50g/l a similar increase in nickel and cobalt recoveries was observed. However, significantly, the 15 Ni:Fe mole ratio in the product decreased from 7.0 to 4.7 due to iron precipitation increasing from 2.2 to 3.2%. These results are inconsistent with those observed with the finer seed. A possible explanation is that the test using the higher seed concentration (Test 10) was 20 conducted significantly later than all the other tests and oxidation of the ferrous ions in the feed liquor appears to have resulted in a higher ferric ion concentration in this solution relative to the previous tests. This is supported by the higher free acid concentration in 25 solution at the end of Test 10 (-17g/l as opposed to -8g/l previously) and the higher sulphur concentration (62% S as opposed to 48% S) in the sulphide product. Both these observations are consistent with H 2 S reacting with Fe(III) in solution according to the following reaction. 30 2Fe(III) + H 2 S 2Fe(II) + 2H* + S Reaction 1 35 The above reaction produces free acid and elemental sulphur as observed in test 10. The presence of Fe(III) in solution would also be expected to have WO 2004/016816 PCT/AU2003/001037 -9 resulted in higher iron precipitation, reducing the Ni:Fe mole ration in the sulphide product. Effect of Hydrogen Sulphide Pressure 5 Previous test work indicated that H 2 S pressure between 30 and 60 psi had a strong influence on metal precipitation. In the current test work the effect of H 2 S pressure was investigated further. 10 Precipitation tests were conducted at 80 0 C, 30 g/l seed, with a P_ 0 of 109 microns. The results are presented in Figure 4. 15 The results show that nickel recovery increased from 97.1 to 99.8% while cobalt recovery increased from 96.8 to 99.7% as H2S pressure increased from 20 to 40 psi while the Ni:Fe mole ratio of the product decreased from 11.3 to 6.6. This corresponds to iron precipitation 20 increasing from 1.3 to 2.3%. These results are all consistent with S2 concentration in solution increasing with H 2 S partial pressure resulting in greater metal recovery and lower 25 selectivity. Column Heap Leach Liquors From the above series of tests the following 30 optimal conditions required for precipitating nickel and cobalt from heap leach liquors were determined: * H 2 S Pressure 20 psi e Seed charge 30 g/l 35 . Temperature 80 0 C e Seed P5 0 45 microns.
WO 2004/016816 PCT/AU2003/001037 - 10 Initially, heap leach liquors were partially neutralised to remove excess free acid and then treated with H 2 S to precipitate nickel and cobalt without a pre reduction stage. This resulted in low nickel and cobalt 5 precipitation and the product was contaminated with iron and elemental sulphur. In addition, the liquor free acid also increased sharply, according to reaction 1. A second batch of liquors was generated and 10 treated in the following sequence of process stages, as discussed below: e Pre-reduction * Neutralisation 15 0 Sulphide Precipitation Pre-Reduction Stage The following pre-reduction stage was selected 20 with the objective of reducing all Fe(III) to Fe(II): Temperature 80 0 C
H
2 S pressure 20 psi Reaction time 90 minutes 25 Initial free acid 40-90 g/l H 2 SO4 The results are summarised in Table 2. Table 2 - Results of Pre-Reduction with H 2 S 30 Sample % Precipitation Final Aq. Assays (g/L) Ni Co Cu Zn Cr Fe(Il) Fe F.A GL-Ev 0.25 0.01 94 0.24 0.02 26.7 26.7 101 GL-Tr 0.67 0.01 87 0.46 0.02 22.2 22.1 104 GL-Kaa 0.08 0.01 81 0.01 0.003 16.7 17.3 58.2 GL-Ak 0.13 0.005 76 0.30 0.12 26.4 26.6 95 The Fe(III) was effectively reduced to Fe(II) WO 2004/016816 PCT/AU2003/001037 - 11 under the conditions employed. Nickel and cobalt precipitation were minimal. Nickel precipitation ranged from 0.083 to 0.67% while 5 cobalt precipitation was less than 0.01%. Copper was the only element which showed significant precipitation, with copper concentrations in solution reduced to less than 1 mg/l. 10 The concentrations of the other elements assayed (Fe, Zn, Cr, Mg, Mn and Al) were not significantly altered by the pre-reduction stage with precipitation consistently being less than 0.5% and typically less than 0.1%. 15 As a result of the Fe(III) reduction the free acid concentration increased and elemental sulphur was generated. 20 The observed increase in free acid concentration in solution was in good agreement with the calculated increase in free acid concentration based on reaction 1 stoichiometry. 25 Residue assays showed sulphur as the main constituent (>80%). The results show that the Fe(III) could be effectively reduced to Fe(II) using H 2 S in the presence of 30 relatively high free acid (40-90 g/l) with minimal nickel and cobalt losses. This is a positive outcome. Neutralisation Stage 35 The liquors generated from the pre-reduction stage were treated with limestone to increase the solution pH to -2 in the neutralisation stage.
WO 2004/016816 PCT/AU2003/001037 - 12 The feed liquor compositions supplied to the neutralisation stage are given in Table 3. 5 Table 3 - Liquor Compositions to Neutralisation Stage Lig. Source "Ni Co DFe IMg Cr DAl Mn Cu Zn DFA GL-Ev 4.27 210 26.7 4.80 622 5.12 497 0.4 5 101 GL-Tr 4.07 197 22.1 3.83 758 4.32 519 0.5 3 104 GL-Ka 4.43 197 17.3 14.2 119 0.347 330 0.6 77 58 GL-Ak 4.14 196 26.6 4.94 565 5.45 470 0.7 3 95 Assays are in mg/L D denotes assays in g/L 10 The liquors were neutralised by being treated with limestone (P 80 =250 microns) at ambient temperature. The results of the neutralisation tests are summarised in Table 4. 15 Table 4 - Results of Liquor Neutralisation Sample % Precipitation Final Aq. Assays (g/L) Ni Co Fe Zn Cr Fe(II) Fe pH GL-Ev 0.37 0.07 0.11 3 0.1 26.8 27.9 2 GL-Tr 0.40 0.16 0.01 14 1 22.0 22.5 2 GL-Ka 0.26 0.05 0.17 0.2 4 15.6 17.3 2 GL-Ak 0.33 0.15 0.10 9 2 26.1 28.3 2 Nickel and cobalt losses by precipitation were low - ranging from 0.2 to 0.4% and 0.05% to 0.16%, 20 respectively. The copper concentration in solution was reduced to below the copper detection limit of 0.1 mg/l. 25 Precipitation of the remaining impurities (Al, Mn, Cr, Fe and Zn) was low, generally less than 1%. The iron essentially remained in the Fe(II) state enabling sulphide precipitation 'from the liquor to be 30 undertaken.
WO 2004/016816 PCT/AU2003/001037 - 13 The residues were mainly composed of gypsum (indicated by high calcium and sulphur assays). 5 Limestone consumption was very high, ranging from 13 to 24 kg/kg (Ni + Co) - due to the high free acid concentration in the solution. Overall nickel and cobalt losses across pre 10 reduction and neutralisation stages were low, ranging from 0.3 to 1.1% and 0.06 to 0.17%, respectively. Sulphide Precipitation Stage 15 Following the pre-reduction and neutralisation stages the clarified liquors were treated with H 2 S to precipitate nickel and cobalt under the following conditions. 20 * H 2 S Pressure 20 psi e Seed charge 30 g/l " Temperature 80 0 C e Seed P 50 45 microns. 25 The composition of the liquors used in the sulphide precipitation stage are summarised in Table 5. Table 5 - Liquor Compositions to Sulphide Precipitation Stage 30 Sample Liquor Assay mg/L) Ni Co Fe Cu Cr Al Mn Zn Mg GL-Ev 4250 210 27940 0.2 621 5080 497 5 4780 GL-Tr 4050 197 22510 0.2 750 4260 519 3 3810 GL-Ka 4420 197 17280 0.2 114 347 330 77 14220 GL-Ak 1 4130 196 28340 0.4 554 5410 470 3 4930 The results of sulphide precipitation are summarised in Table 6.
WO 2004/016816 PCT/AU2003/001037 - 14 Table 6 - Results of Sulphide Precipitation Liquor % Precipitation Solids Assays (%) Solids __ Ni Co Fe Ni Co Fe Cr Al Zn S gNi:Fe GI-Ev 99.2 99.0 1.7 47.6 2.3 5.0 0.13 0.05 0.03 30.8 9.0 GL-Tr 99.3 99.8 1.9 47.5 2.5 4.3 0.08 0.03 0.01 29.7 10.6 GL-Ka 99.3 99.6 2.7 48.7 2.3 4.6 0.02 0.01 0.73 31.3 10.1 GL-Ak 99.4 99.8 1.3 47.0 2.4 4.0 0.10 0.04 <0.01 32.1 11.2 # Mole Ratio 5 Despite the relatively low H 2 S partial pressure, nickel and cobalt recoveries were high (>99%). In optimisation test work the same H 2 S pressure and 10 temperature yielded recoveries of -97% for nickel and cobalt. The higher recoveries observed with the heap leach solutions is attributed to using a finer seed P 5 0 =45 15 microns compared to P 5 o=109 microns for the synthetic solutions. The sulphate levels were similar for synthetic and real liquors (-100 g/1 S042-) and were not expected to have resulted in significant differences in nickel and cobalt precipitation. 20 The solids contained between 4.0 and 5.0% Fe with the Ni:Fe mole ratio ranging between 9.0 and 11.2. These results are in good agreement with the 25 results obtained under similar conditions in the optimisation test work. The results showed that the Ni:Fe mole ratio could be upgraded from a range of 0.14-0.24 in solution to 30 9.0-11.2 in the sulphide product representing approximately a 50 fold upgrade of the nickel values with respect to iron.
WO 2004/016816 PCT/AU2003/001037 - 15 Aluminium and chromium showed increased precipitation as the concentration of these metals in solution increased. However the concentrations of 5 aluminium and chromium in the product remained low. These results are summarised in Figure 5. The aluminium concentration in the product generally increased with aluminium concentration in 10 solution. Aluminium does not form stable sulphides in solution and the increase in aluminium concentration in the product appears to be through adsorption/entrainment with the sulphide. 15 The chromium concentration in the product also increased with chromium concentration in solution. This effect is much stronger with the increase in chromium in the product increasing more steeply with chromium in the PLS compared to aluminium and could indicate that chromium 20 precipitated as opposed to being adsorbed/entrained. Zinc concentration in solution was reduced to between 2 and 3 mg/l. The sulphide products were generally low in zinc (less than 0.03%) due to the 25 relatively low zinc concentration in solution (3-5 mg/l). Only the sulphide generated from the GL-Ka ore contained significant zinc at 0.73% due to the feed solution having a higher zinc tenor (77 mg/1). 30 Copper concentration in the products was low due to copper removal in previous unit operations with copper in the product ranging between 0.01 and 0.03%. Manganese and magnesium concentrations in the 35 products were consistently low at less than 50 ppm and less than 500 ppm, respectively, reflecting the high selectivity of sulphide precipitation against these WO 2004/016816 PCT/AU2003/001037 - 16 elements. CONCLUSIONS 5 From the test work the following conclusions can be drawn. 1. Nickel and cobalt precipitation increased as liquor temperature increased from 40 0 C to 95 0 C. The Ni/Fe 10 separation appeared to reach a maximum at 80 0 C. Aluminium, chromium, manganese and magnesium precipitation were not affected over the temperature range investigated. 15 2. Increased seed surface area increased nickel and cobalt recovery. 3. Increasing the partial pressure of H 2 S from 20 to 40 psi increased nickel recovery from 97.1 to 99.8% and 20 the cobalt recovery from 96.8 to 99.7%. The Ni:Fe mole ratio in the product decreased from 11 to 6.7. From the test work conducted on the heap leach liquors the following conclusions can be drawn. 25 1. Liquors can be treated with H 2 S gas in a pre reduction stage to reduce Fe(III) to Fe(II) with low nickel and cobalt losses (ranging from 0.08% - 0.67% and <0.1%, respectively). Copper was the only 30 impurity significantly removed during pre-reduction with copper concentration in solution being reduced below 1 mg/l. 2. The neutralisation stage effectively increased the pH 35 of the liquor from the pre-reduction stage to -2 while maintaining iron in the Fe(II) state. Nickel and cobalt losses during the neutralisation stage WO 2004/016816 PCT/AU2003/001037 - 17 were 0.2%-0.4% and 0.05%-0.16%, respectively. The residues were mainly gypsum. Impurity removal during neutralisation was generally less than 1%. 5 3. Sulphide precipitation was successful in precipitating greater than 99% of the nickel and cobalt, producing a precipitate with a Ni:Fe mole ratio between 9 and 11.2, from solutions containing ~ .4g/L nickel and 17-27 g/l iron. Chromium and to a 10 lesser extent aluminium were present in the sulphide product in minor quantities. Zinc concentration in solution was reduced to -3 mg/l. Many modifications may be made to the present 15 invention described above without departing from the spirit and scope of the invention.
Claims (20)
1. A process for recovering a valuable metal in the form of nickel from a leach liquor obtained by processing 5 laterite ores and concentrates that are contaminated with iron by any leaching process including one or more of heap leaching, pressure leaching, bacterial oxidation leaching, and atmospheric tank leaching, the leach liquor containing the valuable metal and iron in solution, which process 10 includes the following steps after the leach process of: (a) processing the leach liquor by reducing ferric ions to ferrous ions in the leach liquor using a suitable gaseous reductant; 15 (b) neutralizing the processed leach liquor to reduce the free acid concentration in solution to levels suitable for nickel precipitation while maintaining iron in the ferrous state; and 20 (c) precipitating the valuable metal using the reductant and seed particles under process conditions, including one or more of seed particle size, seed composition, and 25 temperature, that are selected to maximise nickel precipitation and to minimise iron precipitation.
2. The process defined in claim 1 wherein the 30 reduction step (a) includes reducing ferric ions to ferrous ions using the reductant in the presence of an initial concentration of 40-90 g/l free acid.
3. The process defined in claim 1 or claim 2 35 wherein the gaseous reductant is 123.
4. The process defined in any one of the preceding NWb-~ O~d60-69T6 .U IMpeci~memded pa"e 2 OOM5-7.doc - 19 claims wherein the neutralisation step (b) increases the pH of the solution to 2.
5. -The process defined in any one of the preceding 5 claims wherein the valuable metals are nickel and cobalt.
6. The process defined in any one of the preceding claims wherein the laterite ores are ores that contain nickel in a chlorite mineral phase. 10
7. -The process defined in any one of the preceding claims wherein the process conditions for the precipitation step (c) include operating at a partial pressure of the gaseous reductant of less than 60 psi. 15
8. The process defined in claim 7 wherein the gas partial pressure is less than 40 psi.
9 - The process defined in claim 8 wherein the gas 20 partial pressure is less than 30 psi.
10. -The process defined in claim 9 wherein the gas partial pressure be less than 25 psi. 25
11. The process defined in any one of the preceding claims wherein the process conditions for the precipitation step (c) include operating at a liquor temperature of at least 50 0 C. 30
12. The process defined in claim 11 wherein the liquor temperature is at least 60 0 C.
13. The process defined in any one of the preceding claims wherein the seed particles for the precipitation 35 step (c) have a particle size of P 50 less than 100 micron.
14. The process defined in claim 13 wherein the N:\Melbourn\Ca\Punt\4 6M AU ad~eW~ d pge 209--7.d - 20 particle size of the seed particles is P 50 less than 80 micron.
15. The process defined in claim 14 wherein the 5 particle size of the seed particles be Pso less than 60 micron.
16. -The process defined in any one of claims 13 to 15 wherein the seed particle concentration for the 10 precipitation step (c) is greater than 30g/l.
17. -The process defined in claim 14 wherein the seed particle concentration is greater than 40g/l. 15
18. The process defined in any one of the preceding claims wherein the ratio of iron and the valuable metal in the leach liquor supplied to step (a) is greater than 2:1.
19. The process defined in claim 18 wherein the ratio 20 is greater than 3:1.
20. The process defined in claim 19 wherein the ratio is greater than 5:1. NMidbour u ueMb60-4699946846.AU- ISpdsmemed pmu 2009-S-7 ice
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| Application Number | Priority Date | Filing Date | Title |
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| AU2003249789A AU2003249789B2 (en) | 2002-08-15 | 2003-08-15 | Recovering nickel |
| AU2009212926A AU2009212926A1 (en) | 2002-08-15 | 2009-09-03 | Recovering nickel |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2002950815A AU2002950815A0 (en) | 2002-08-15 | 2002-08-15 | Recovery nickel |
| AU2002950815 | 2002-08-15 | ||
| AU2003249789A AU2003249789B2 (en) | 2002-08-15 | 2003-08-15 | Recovering nickel |
| PCT/AU2003/001037 WO2004016816A1 (en) | 2002-08-15 | 2003-08-15 | Recovering nickel |
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| AU2009212926A Division AU2009212926A1 (en) | 2002-08-15 | 2009-09-03 | Recovering nickel |
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|---|---|---|---|---|
| US2722480A (en) * | 1954-06-21 | 1955-11-01 | Chemical Construction Corp | Catalytic precipitation of nickel, cobalt and zinc sulfides from dilute acid solutions |
| US4110400A (en) * | 1977-08-01 | 1978-08-29 | Amax Inc. | Selective precipitation of nickel and cobalt sulfides from acidic sulfate solution |
| GB2049646A (en) * | 1979-05-10 | 1980-12-31 | Inco Ltd | Separation process |
| SU704231A1 (en) * | 1977-05-11 | 1981-07-30 | Государственный Научно-Исследо-Вательский Институт Цветных Метал-Лов "Гинцветмет" | Method of processing ferrous nickel-cobalt laterite ores |
| JPS56136940A (en) * | 1980-03-28 | 1981-10-26 | Mitsubishi Metal Corp | Recovering method for copper, nickel and cobalt in solution leached from manganese nodule with sulfuric acid |
| US4410498A (en) * | 1980-11-05 | 1983-10-18 | Falconbridge Nickel Mines Limited | Acid leaching of nickel from serpentinic laterite ores |
| JPS6043446A (en) * | 1983-08-13 | 1985-03-08 | Mitsubishi Metal Corp | Method for recovering nickel from acidic aqueous solution containing nickel ion |
| US4547348A (en) * | 1984-02-02 | 1985-10-15 | Amax Inc. | Conditioning of laterite pressure leach liquor |
| CN1309194A (en) * | 2000-11-28 | 2001-08-22 | 华东理工大学 | Process for regenerating waste etching liquid containing Ni and FeCl3 and recovering Ni |
| WO2001086010A1 (en) * | 2000-05-10 | 2001-11-15 | Kronos Titan Gmbh & Co. Ohg | Method for eliminating nickel ions and lead ions from ferrous salt solutions |
-
2003
- 2003-08-15 AU AU2003249789A patent/AU2003249789B2/en not_active Expired - Fee Related
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2722480A (en) * | 1954-06-21 | 1955-11-01 | Chemical Construction Corp | Catalytic precipitation of nickel, cobalt and zinc sulfides from dilute acid solutions |
| SU704231A1 (en) * | 1977-05-11 | 1981-07-30 | Государственный Научно-Исследо-Вательский Институт Цветных Метал-Лов "Гинцветмет" | Method of processing ferrous nickel-cobalt laterite ores |
| US4110400A (en) * | 1977-08-01 | 1978-08-29 | Amax Inc. | Selective precipitation of nickel and cobalt sulfides from acidic sulfate solution |
| GB2049646A (en) * | 1979-05-10 | 1980-12-31 | Inco Ltd | Separation process |
| JPS56136940A (en) * | 1980-03-28 | 1981-10-26 | Mitsubishi Metal Corp | Recovering method for copper, nickel and cobalt in solution leached from manganese nodule with sulfuric acid |
| US4410498A (en) * | 1980-11-05 | 1983-10-18 | Falconbridge Nickel Mines Limited | Acid leaching of nickel from serpentinic laterite ores |
| JPS6043446A (en) * | 1983-08-13 | 1985-03-08 | Mitsubishi Metal Corp | Method for recovering nickel from acidic aqueous solution containing nickel ion |
| US4547348A (en) * | 1984-02-02 | 1985-10-15 | Amax Inc. | Conditioning of laterite pressure leach liquor |
| WO2001086010A1 (en) * | 2000-05-10 | 2001-11-15 | Kronos Titan Gmbh & Co. Ohg | Method for eliminating nickel ions and lead ions from ferrous salt solutions |
| CN1309194A (en) * | 2000-11-28 | 2001-08-22 | 华东理工大学 | Process for regenerating waste etching liquid containing Ni and FeCl3 and recovering Ni |
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