AU2007234576B2 - Method of making up and treating nickel concentrates - Google Patents

Abstract

Abstract The invention relates to a method of making up and treating sulfidic, difficult-to process nickel concentrates rich in various magnesium silicates. According to the 5 invention, the adverse influence of magnesium silicates is mitigated by making use of their solubility. The feasibility of a concentrate for processing is thus iYprOved and a concentrate is obtained which is more suitable for a pytotailurgical or hydronetallurgicalereatment. Millerite concentrate 99 - 597 -=- New concentrate Original Z 95 concentrate 0 10 20 30 40 50 Ni % Mixture of talc concentrate and milierite concentrate 60 - Original 50 concentrate 4 concontre 30 - 0 5 10 15 20 25 Ni- %

Description

AUSTRALIA Patents Act COMPLETE SPECIFICATION (ORIGINAL) Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: Name of Applicant: Norilsk Nickel Finland Oy Actual Inventor(s): Seppo Sakari Jounela, Jaakko Henrik Korkiala, Lars Erik Snare Address for Service and Correspondence: PHILLIPS ORMONDE & FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: METHOD OF MAKING UP AND TREATING NICKEL CONCENTRATES Our Ref: 816753 POF Code: 1124/485036 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): -1 8006q 1A Method of making up and treating nickel concentrates Background art The invention relates to a method of making up and treating sulfidic nickel 5 concentrates which contain magnesium silicates. A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that that document or matter was known or that the information it contains was part of the common general knowledge as at the priority 10 date of any of the claims. Throughout the description and claims of this specification the word "comprise" and variations of that word, such as "comprises" and "comprising", are not intended to exclude other additives, components, integers or steps. 15 Both in pyro- and hydrometallurgical processes, use is currently made of concentrates which originate from nickel mineralisations of increasingly poor quality in terms of feasibility for enrichment and processing. The presence of magnesium-oxide (MgO) bearing silicates in nickel mineralisations is very often a source of processing 20 problems. These silicates undermine yields of metals, as well as their contents in concentrates. Because of gangue minerals, which are difficult in terms of enrichment engineering and accumulate easily in a concentrate, particularly those containing magnesium 25 silicate, such as talc (Mg 3

(OH)

2 Si 4

O

1 O) , chlorite ((Mg,AI,Fe) 1 2 (Si,AI) 8 0 2 0

(OH)

1 6 ) and serpentinite minerals (Mg 3 Si 2

O

5

(OH)

4 ), but also so-called expanding silicates, such as pyroaurites (Mg 6 Fe3+ 2

(CO

3

)(OH)

1 6

H

2 0), hydrotalcite (Mg 6

AI

2

(CO

3

)OH

16 4H 2 0), iowaite (Mg 4 Fe3+(OH) 8 0Cl2-4H 2 0), woodalite (Mg 6 Cr 2

(OH)

16 Cl 2 4H 2 0) and stictite (Mg 6 Cr 2 (C0 3

)(OH)

16 4H 2 0), it is extremely difficult to obtain concentrates, which are 30 sufficiently pure, especially from the standpoint of a pyrometallurgical, but also hydrometallurgical treatment, and which are sufficiently low in MgO-content. Regarding such raw materials, it is difficult in enrichment engineering to find conditions in which sufficiently high-grade concentrates could be obtained by direct 35 processing. Qualitatively unsatisfactory concentrates are low in iron (Fe) content and high in MgO contents, resulting from high MgO-contents in gangues. In particular, the ratio SPEC-I157S.0ac 2 Fe/MgO is often low as concentrates have low contents of iron sulfides, such as for example pyrrotite (FeS) and pyrite (FeS 2 ,), or iron-bearing valuable minerals, such as pentlandite ((Fe,Ni) 9

S

8 ). Mineralisations such as this contain often magnetite (Fe 3 0 4 ). In the enrichment stage, the concentrate develops mixed valuable metal-magnetite 5 grains, whose iron content for the large part often consists of magnetite. The low ratio Fe/MgO leads to trouble in a pyrometallurgical treatment since, if the MgO-content of slag produced in smelting is higher than 11 %, the slag shall develop a viscosity high enough to impede a removal of the slag from the furnace. In a hydrometallurgical treatment, on the other hand, magnesium silicates consume a lot of oxygen, which is 10 a major cost factor. When the enrichment is conducted by flotation, a normal yield from high-grade or mineralogically clearly defined ores by a sufficient number of repetitions consists of concentrates which are good for further processing. The expression high-grade or 15 mineralogically clearly defined ores is used here in reference to ores, which do not substantially contain or contain just a small amount of troublesome gangue minerals, particularly magnesium silicates. In these concentrates, the ratio Fe/MgO does not cause problems. 20 A reduction of the MgO-content in concentrate has been pursued by subjecting concentrates to several successive iteration and washing operations by using various depressor chemicals, such as for example carboxy-methyl cellulose (CMC). In the event that valuable minerals present in exploitable ore exist in the form of finely 25 disseminated deposits and mixed grains, a high-grade concentrate is difficult to achieve with an economically viable yield. The production of a high-rate purity concentrate requires milling to an extremely fine form, i.e. a very high degree of liberation. 30 In most cases, the concentrate is good for processing, especially good for smelting, as long as the ore has sulfide minerals which contain iron, such as for example magnetic pyrite (FeS), pyrite (FeS 2 ), pentlandite ((Fe,Ni)gSa), etc. and these sulfide minerals can be included in the concentrate. The silicates present in an ore deposit may also exhibit properties making the same reluctant to concentrate or removable 35 from the concentrate in iteration processes. In the event that the ores with a content of valuable minerals do not contain iron, such as for example millerite (NiS) ores, but do contain readily concentrating magnesium silicates, such as talc and serpentine, it will be extremely difficult to provide the SPEC-816753.docx 3 concentrate with a value of the ratio Fe/MgO required by a pyrometallurgical treatment. In this case, the iron must be extracted from minerals totally other than so called valuable minerals, such as for example from pyrite, pyrrotite or magnetite. 5 Description of the invention According to the invention, magnesium silicate particles are removed from the surfaces of nickel mineral particles by dissolving at an acidic pH. Thus, a lesser amount of magnesium silicate will migrate along with nickel mineral particles, 10 especially in view of a further enrichment by flotation. Removed particles also form agglomerates with silicate particles of the opposite sign or may disperse. The positively charged magnesium silicate matter may contain especially serpentine and the negatively charged one especially talc. 15 The ore is preferably milled to the range of D 50 = 10 pm +/- 5 pm. Thus, in particular, the amount of silicates with poor solubility can also be reduced. A preferred pH-range is 3-6, the particularly preferred being 3.5-4.5. 20 The method according to the invention enables improving the feasibility of concentrates for processing. This enables making use of an ore or concentrate which is otherwise economically and technically unfit or poorly feasible for processing. The method enables enriching the ore as early as in a first enrichment stage to become more feasible for further processing or to re-enrich the resulting concentrate to 25 become a concentrate of higher quality in terms of its feasibility for processing. The method enables improving the feasibility for processing by processing raw materials directly, making use of the solubility of magnesium silicates, or by combining ores of dissimilar mineralogies or concentrates of dissimilar mineralogies 30 derived from different ores for making the same more suitable for processing. The quality-related problems of concentrates result from the properties of minerals. Gangue minerals often contain not only quartz (SiO 2 ) but also miscellaneous iron (Fe-), aluminium (Al-), manganese (Mn-), and magnesium (Mg-) compounds, which often 35 involve alkaline hydroxides (-OH), carbonates (-CO 3 ) and sulfates (-SO 4 ), and possibly also magnetite (Fe 3 04). Particularly troublesome, in terms of both pyrometallurgy and hydrometallurgy, are various magnesium silicates. SPEC416753.ocx 4 Gangue minerals are often soft and possess a high specific surface area and a high solubility. In many instances, they are also readily expansible, i.e. water absorbent, powerfully charged electrically, having thereby a high inclination for co 5 concentration with valuable minerals. Co-concentration is also a result of structural aspects and a mixed granularity with valuable minerals. Powerful flocculation and adsorption effects amongst valuable minerals and also with other gangue minerals, such as various silicates, are characteristic thereof. 10 Maiy of these magnesium-bearing silicates, such as for example serpentine and chlorite, are inh-erently hydrophilic while talc, for example, is hydrophobic. These hydrophilic magnesium-oxide bearing minerals may co-migrate into the concentrate in the form of very fine particles along With actual valuable mineral particles. They may exist as inclusions in valuable mineral particles and may 15 activate in cohjunction with copper activation as copper is added to activate th.0 slow flotation of pentlandite. The very reason for this is in turn often the adsorption of electidally active silicates to the surfaces of pentlandite particles. A useful enrichment method in implementing the Invention is for example highly 20 advanced selective flotation, which may include several intermediate product milling and grading processes, as well as repetition stages. Milling can be effected by using various prior known methods, such as rod or ball milling. According to one preferred Implementation of the invention, there has now been 25 discovered a distinctly finer grain size range Dso = 10 pm +/- 5 pm (D6 0 indicates that 50 % of particles have a diameter smaller than the given value) different from the conventional grain size range used in flotation. Another preferred aspect Is to use favorable solution-related chemical conditions and special features (pH, state of charge in opposite sign), resulting from the mineralogy of minerals, particularly 50 so-called attle minerals, contained in concentrates, which are employed to enable processing. One implementation of the presently invented method comprises making up a concentrate, in which the amount of magnesium silicates has been successfully 35 reduced to such a low level that the concentrate is feasible for further processing and for use in a pyrometallurgical or hydrometallurgical further treatment, either as such or by compounding the concentrate with a higher-grade concentrate or by still increasing the iron content of the concentrate for example by means of pyrite.

5 Hence, in general, the ratio Fe/MgO in a concentrate good for pyrometallurgical treatment must be at least about 2.6. Said limit of the ratio Fe/MgO is a bottom limit and, regarding the feasibility for treatment, the higher the ratio, the better. As for a hydrometallurgical concentrate, there is no such limit. 5 Another way of determining the ratio Fe/MgO of a concentrate is that the slag produced in a pyrometallurgical treatment must have an MgO content of not higher than 11 %. If the MgO content of slag is higher than that, the slag shall have a viscosity so high that the removal of slag from the furnace will cause trouble at the 10 temperature otherwise normally used for effecting the pyrometallurgical treatment of nickel. Raising the temperature naturally enhances the fluidity of slag, yet is not economically sensible and affects the longevity of equipment. The nickel concentrate of distinctly improved quality, produced according to the invention and containing less MgO, can be processed more easily either pyrometallurgically (e.g. smelting) or 15 hydrometallurgically (e.g. pressure solution). The refuse, which emerges from a re-enrichment process which increases the valuable metal content of a concentrate, is low in its valuable mineral content and rich in gangue minerals and harmful silicates, such as magnesium silicates. Depending on 20 the quality of refuse, and principally on attle minerals (e.g. serpentine, talc, etc.) contained therein, it is possible to still have it treated hydrometallurgically (especially by pressure solution) and to provide an economically viable process. By enriching the finely divided silicate matter present in the original concentrates to a significant extent into the refuse ore in correct solution-chemical conditions, is possible to obtain a 25 concentrate of higher quality in terms of its feasibility for processing, which is more suitable for processing. The invention is implemented by exploiting the opposite states of electrical charge of silicate minerals present in ore or concentrate or to be added intentionally therein in 30 the form of ore or concentrate. Thus, the silicates with a charge of opposite signs offset the influence of each other, end up in refuse, and the quality of concentrate improves. Regarding the harmful silicates most commonly found in nickel concentrates, serpentine and amphibole are positive (+sign) as regards their zeta potential, and talc as well as chlorite are in turn negative (-sign) over an extensive pH 35 range. As for valuable minerals, for example pentlandite has a zeta-potential of -sign also over a very extensive pH-range but as acidity increases, the zeta-potential value of pentlandite decreases, SPEC-816753.docx approaching zero. The surfaces of pentlandite are covered to a significant extent by serpentine particles with a powerful positive charge in terms of their zeta potential, and the flotation of pentlandite is slow. The kinetics of flotation decelerates and the metallurgical yield of pentlandite diminishes. On the other 5 hand, talc always flotates easily because of Its hydrophobicity. Thus, combinations of various ores can be made up for providing the sludge appropriately with silicates of opposite signs. When the pH-rahge is distinctly acidic, it is also possible to exploit the dissimilar 10 solubilities of silicates In the process of upgrading the quality of concentrates. Serpentine, for example, dissolves and gradually decomposes in response to an acid in acidic conditions. As the level of acidity increases, the serpentine particles with a positive zeta-potential disengage from the surfaces of pentlandite and become engaged with talc particles of a negative zeta-potential, and these 15 agglomerates end up in refuse ore. The serpentine particles also begin to partially break up by dissolving as the acidity increases. Thus, for example, the feasibility of a serpentine- and talc-bearing concentrate for processing can be substantially improved by reducing the amount of MgO Content increasing magnesium silicates, such as serpentine and talc, present In the concentrate. The processability of concentrates containing magnesium silicates, such as for example serpentine, soluble in acids, can be improved by raising the acidity level of slurry, whereby the magnesium silicate particles soluble in acids disengage from the surfaces of valuable mineral particles and begin to break up in response 26 to dissolving. Thus, the concentrate improves In terms of its feasibility for processing and the ratio Fe/MgO rises in value. However, it Is not absolutely hecessary to dissolve the silicates completely because, depending on the charge thereof, It may be easier for them to end up in refuse ore. 30 The refinement and enrichment of a concentrate containing readily flotating but difficult-to-dissolve magnesium silicates, such as talc and chlorite, is not possible to any significant extent merely by means of a rise in acidity, because talc and chlorite do not really dissolve or dissolve poorly In acids. In this case, in particular, in view of raising the valuable metal content of a concentrate, it is preferred to 35 have a sufficiently fine degree of liberation. This way, the valuable minerals can be effectively separated from silicates and other impurities.

7 Examples the invention will be Illustrated further by way of the following examples, the first of which describes upgrading the NiS-quality of a millerite concentrate, which has a very high MgO content and has been enriched from serpentine-bearing nickel ore, the second one describes an attempt to improve conventionally the processability of a pentlandite concentrate, which has a high talc content and has been enriched from nickel ore, and the third one describes a co-enrichment process of the above-indicated high talc-content pentlandite concentrate and the 10 high serpentine-content millerite concentrate. The nickel ores, the original millerite and talc concentrates of which have been enriched by flotation, have been subjected to initial treatments conventionally by usiig highly advanced selective flotation, involving in addition to preliminary 15 flotation, a number of iteration flotations which are carried out by using chemicals, such as carboxy-Methyl cellulose (CMC), with a depressing effect on silicates. The objective has been to reduce, by conventional methods, as much as possible the amount of magnesium silicates inclined to flotation in a concentrate. 20 Example 1. Improving the NiS-processability of millerite concentrate Chemical analyses are presented in table 1, mineralogical analyses In table 2, and enrichment results in table 3. The Ni-yield as a function of the Ni content Is shoWn in fig. 1. Z5 Nickel ore (0.558 % Ni, 2.8 % Fe and 0.11 % pentlandite and 0.13 % millerite), which contained 78.85 % serpentine and 1.19 % talc, has been first subjected to flotation te obtain a nickel concentrate (millerite concentrate NiS). The concentrate contained 12.4 % Ni (15.52 % pentlandite and 12.07 % rmillerite), 7.08 % Fe and 30 28.1 % MgO, the latter consisting of serpentine (47.36 %) and talc (2.62 %) present in the concentrate. The conducted trials involved a flotation treatment of this extremely difficult-to enrich, serpentine- and talc-bearing nickel concentrate, the predominant source of 35 whose magnesium silicate content was serpentine. The objective was to improve, according to the invention, the feasibility of the concentrate for processing in view of pyro-or hydrometallurgical further processing with a yield as high as possible.

8 Table 1. Chemical analyses of millerite ore and concentrate Elements Millerite MllIerite Ore -1 mm Concentrate Ni 0.552 12.4 Cu 0.018 0.076 Co 0.015 0.348 Fe 2.81 7.08 S 0.39 8.89 MgO 41.1 28.1 Sio2 34.7 25.2 Table 2. Mineralogical analyses of millerite ore and concentrate Minerals Millerite Millerite Ore Concentrate Pentlandite 0.11 15.52 Heazlewoodite 0.07 0.85 Millerite 0.13 12.7 -Vallerite 0.18 Pyrrotite 0.06 Pyrite 1.32 Magnetite 1.37 5.64 Magnesite 7.69 9.69 Serpentine 78.85 47.36 Talc 1.19 2.62 Chloride 4.24 1.12 9 Table 3. Enrichment results of millerite concentrate Element Concentrate Pre- Pre- Iterated Iterated Refuse Original concentrate concentrate Concentrate Concentrate ER1-4 ER1-4 KR4 KR4 Yield Yield %_% % _ % % % Ni 12.4 26.5 97.6 40.9 93.1 0.59 Co 0.35 0.7 97.0 1.1 91.9 0.02 Cu 0.08 0.1 79.6 0.1 62.6 0.02 Fe 7.08 10.4 55.3 11.9 39.1 7.6 Mg 10.09. 8.6 26.2 2.2 4.1 22 O 16.9 14.3 26.2 3.65 4.1 36.5 Ca 0.2 0.2 39.4 0.13 16.9 0.26 Fe/IMgO 0.42 0.73 3.22 0.208 Because the magnesium silicate contained in the concentrate Is predominantly (47.36 %) in the form of serpentine, the enrichment was conducted in acidic conditions at a pH of 4 (the most functional pH-range being 3-6), at which the serpentine particles disengage from the surfaces of valuable minerals, such as pentlandite, and, depending on pH-level, become at least partially dissolved and lose their flotation ability, ending up In refuse ore. This is clearly evident from table 10 3. After four iterations, the nickel content has risen from 12.4 % to 40.9 % With a very high yield level (93.1 %). The pre-concentrate has a content without Iteration of 26.5 % Ni and a yield of 97 %. The Fe-content rose from 7.08 % to the pre concentrate's 10.4 % with a yield of 55.3 %, and the four times iterated concentrate has a content of 11.9 % Fe and a yield of 39 %. The MgO-content in the pre-concentrate was 14.3 % and in the four times iterated concentrate it was 3.6 %, while the yield was as low as 4.1 %. The ratio Fe/MgO progressed from 0.42 In the original concentrate to 3.22 in the four times iterated concentrate, which concentrate is for example feasible for smelting. 20 A rematkable improvement In the original concentrate's feasibility for processing has bee provided by making use of the solubility of silicate mineral's serpentine within an acidic pH-range, and it has been possible to disengage the serpentine from the surfaces of a valuable mineral, in this case pentlandite. Hence, this has enabled, for example, making the concentrate good for smelting, 25 10 Example 2. Improving the processability of talc concentrate conventionally (reference example) Chemical analyses are presented in table 4, mineralogical analyses in table 5, and 5 enrichment results in table 6. The Ni-yield as a function of the Ni-content Is shown in fig. 2 in reference to example 3. Talc are (0.492 % Ni, 3.15 % Fe and 0.95 % pentlandite and 0.27 % violarite), which contained 47.56 % serpentine and 19.56 % talc and 3.45 % chlorite, has 10 been first subjected to flotation to obtain a nickel concentrate. The concentrate contained 6.8 % Ni, 3.85 % pentlandite and 3.91 % violarite, 17.7 % Fe and 18.07 % MgO, the latter consisting of serpentine 3.31 %, talc 32.59 %, and chlorite 13.11 % present in the concentrate. 15 The conducted trials involved a flotation treatment of this extremely difficult-to enrich, serpentine- and talc-bearing nickel concentrate, the magnesium silicate content of which consisted predominantly of talc. The objective was to improve the quality of the concentrate and its feasibility for pyro- or hydrometallurgical further processing with a yield as high as possible. 20 Table 4. Chemical analyses of talc ore and concentrate Elements Talk ore Concentrate -1mm Ni 0.492 6.8 Cu 0.028 0.29 Co 0.019 0.23 Fe 3.15 17.7 Mg 22.56 10.9 MgO 37.28 18.07 C8, _0.29 S 0.84 14.5 Fe/MgO 0.08 0.98 II Table 5. Mineral distributions relevant to talc ore, talc concentrate, as well as a rMixture of talc concentrate and millerite concentrate Mineral Talc Talc concentrate Talc + millerite Ore Original Test 3 Test 4 -1 mm Concentr Concentr Refuse Concentr Refuse % ate ate % ate % % KR2 KR2 entlandite 0.95 3.85 26.44 6.42 26.02 0.54 Pentindite others 0.02 6.90 1.68 2.08 0.33 0.13 Violarite 0.27 3.91 12.94 2.48 36.43 0.13 HealzeWoodite 0.24 0.00 0.06. Milletite 0.03 11.11 2.52 5.94 0.34 Polydymite 0.00 0.03 2.73 0.57 2.71 0.03 Gersdorfite 0.01 0.06 0.07 0.02 0.05 0.03 FeNi sulfate 0.00 0.86 0.62 1.86 0.48 0.07 Chalcocite_ Bornite 0.00 0.00 0.00 0.01 Chalcopyrite 0.01 0.83 0.79 0.10 0.39 Vallerite 0.00 0.44 0.28 0.26 1.96 0.35 Pyrratite 0.81 12.39 9.69 6.54 15.25 1.87 Pyrite 0.17 2.68 4.03 1.01 3.15 0.08 Sphalerite 0.02 0.04 0.01 0.03 0.01 A6enopyrite 0.05 0.00 0.01 0.03 Magnetite 1.28 2.48 3.30 8.63 0.21 10.62 Chrornite.- 0.03 0.22 0.08 0.27 0.01 0.38 Muscovite 0.24 0.08 0.00 0.04 0.00 0.02 Goethite 0.06 2.42 0.57 3.86 0.04 4.79 Ilinenite 0.06 0.00 0.00 0.01 0.01 Rutile 0.00 0.00 0.01 Magnesite 16.49 4.59 0.19 5.53 0.06 4.32 Dolormite 0.97 0.01 0.09 . 0.19 Calcite 0.00 0.00 0.00 0.01 0.00 Serpentine 47.56 3.31 0.52 44.29 0.04 52.73 Talc 19.56 32.59 19.30 3.05 3.06 17.89 Chlorite 3.45 13.11 2.57 7.39 0.30 2.98 12 Biotite 0.58 3.60 0.62 0.47 0.57 0.07 Quartz 0.06 0.04 0.01 0.03 0.01 0.02 Plagioclase 0.49 0.03 0.02 0.02 0.01 0.01 Orthoclase 0.02 0.00 0.02 0.00 Tremolite 0.55 0.08 0.01 0.01 0.01 0.10 Epidote 0.02 0.02 0.01 Titahite 0.00 Apatite 0.03 0.01 Not determined 6.31 5.39 2.11 2.37 2.86 2.31 TOTAL 100 100 100 100 100 Ehrichment results reveal directly (table 6) that valuable metal contents and the ratio Pe/MgO do not Improve. The NI-content in the original concentrate is nearly the same as after the re-enrichmerit, and so is the ratio Fe/MgO. Talc hardly dissolves at all, nor does It react with oxygen within an acidic pH-range at pH 4 (the most functional pH-range being 3-6) used in conventional flotation. As a result, the flotation of talc takes place specifically in concentrate. Serpentine content changes from 3.31 % to 0.52 %, chlorite content from 13.11 % to 2.57 %, but talc content only from 32.59 % to 19.30 %. Serpentine and chloride proceed 10 Into refuse within an acidic range, but talc is still readily susceptible to go along with the concentrate and to flotate (table 5). The original concentrate does not include a sufficient amount of any talc (32.59 %) depressing or binding opposite sign (+sign) mineral, such as serpentine (3.31 %). Thus, the quality of concentrate cannot be Improved with a traditional method without a significant loss of yield. 15 13 Table 6. Enrichment results for talc concentrate Eleinent Concentrate Pre- Pre- Refuse Refuse original concentrate concentrate Yield ER1-3 ERI-3 Yield Ni 6.8 7.3 41.2 6.9 58.8 Co 0.23 0.23 42.3 0.21 57.7 Cu 0.29 0.39 46.7 0.29 -53.3 Fe 17.7 23.6 55.3 12.6 .44.7 10.9 3 22.4 6.9 77.6 18.4 5.1 22.4 11.6 77.6 Ca 0.29 0.2 29 0.3 71 F6/MgO 0.96 1.28 1.07. Example 3. Co-flotation of a mixture of talc-bearing pentlandite concentrate and niillerite concentrates with a method of the invention The susceptibility to flotation of an original talc concentrate can be enhanced by introduding therein a serpentine-bearing millerite concentrate, because talc is negative (-sigh) in its zeta-potential and serpentine Is positive (+slgn) over an 10 acidic pH-range (the most functional pH-range being 3-6). Serpentine particles can be brought to disengage from the surfaces of valuable mineral particles, such as pentlandite, whose negative charge has already weakened in the discussed pH-range, and to bind talc particles which have a more powerful negative charge. As the disengagement of serpentine particles Is achieved from the pentlandite 1 surfaces of valuable minerals, the flotation of valuable minerals accelerates kinetically and the metallurgical yield is Improved. The quality and yield of the concentrate become better and the serpentine-talc agglomerates end up in refuse ore. 20 A chemical analysis of millerite concentrate is presented In table 1 and a mineralogical analysis in table 2. A chemical analysis of talc concentrate Is presented in table 4d and a mineralogical analysis in table 5. 25 14 Entichment results regarding the co-flotation of millerite concentrate and talc concentrate are presented in table 7 and in fig. 2. Table 7. Results from co-enrichment of talc and millerite concentrates Element Concentrate Pre- Pre- Iterated Iterated Refuse original concentrate concentrate concentrate concentrate ER14 ERI-4 KR2 KR2 Yield Yield Ni 6.8. 15.5 97.5 22.6 88.1 0.59.. Co 0.23 0.5 97.4 0.77 89.1 0.02 Cu 0.29 0.3 91.4 0.42 81.5 0.04 17.7 17.1 78.2 22.7 64.1 7.01 M 10.9 4.3 26.1 0.85 3.2 17.7 moO 18.1 7.1 26.1 1.41 3.2 29.4 Ca 0.29 0.2 45.3 0.13 23.9 0.27 Fe/MoO 0.98 2.41 16.1 0.24 Co-enrichment has been conducted by flotating a mixture, which contained equal afmouhts of talc (50 %) and millerite concentrate (50 %), within an acidic pH-range at pH 4 (the most functional pH-range being 3-6). The talc concentrate contained 10 3.31 61 serpentine, 32.59 % talc, and 3.45 % chlorite. On the other hand, the rmillerite concentrate contained 47.36 % serpentine, 2.62 % talc, and 1.12 % chlorite. The results of co-enrichment (tables 5 and 7) Indicate that, in the case of a tWice Iterated concentrate (KR2), the concentrate has an NI-content of 22.6 % with a yield of 88.1 %. As for the pre-concentrate, the NI-content is 15.5 % and the 15 yleid is 97i5 %, respectively. The Fe-content (KR2) is 22.7 % Fe and the MgO conteht (KR2) is 1.41 % with a yield of 3.2.%. The ratio Fe/MgO is 16.1, which enables subjecting the concentrate to a pyrometallurgical treatment, for example smelting. The ratio Fe/MgO of the pre-concentrate is also 2.41 and almost good enough for smelting. Hence, the silicates with electrical charges of opposite signs 20 (+sign serpentine and -sign talc) have overturned each other's Influences and the flotation of valuable metals has kinetically accelerated, as well as the enrichment result has clearly Improved, even by arithmetic calculation.

15 A procedure like this, i.e. by making use of oppositely signed charges of silicates in various pH-onditions, improves the quality of concentrates and the feasibility thereof for both pyro- and hydrometallurgical further processing. 5 Tables 5 and 7 reveal that the resulting concentrate is by all accounts a concentrate which is more applicable to pyro- as well as hydrometailurgical further 'processing than the original concentrate presented In table 5, The contents have been presented in percentage by weight. 10 It is evident from the tables that both concentrates, obtained from the original doncentrates, can be utilized in a technically and economically sensible manner. Thus, choosing the type of process-metallurgical treatment is simple, depending on requirements set by a given metallurgical treatment.

Claims (7)

1. A method of making up and treating sulfidic nickel concentrates which contain magnesium silicates, wherein sulfidic pulverized nickel ores containing magnesium 5 silicates are processed for a concentrate slurry which contains both positively charged magnesium silicate matter and negatively charged magnesium silicate matter, magnesium silicate particles adsorbed on the surfaces of nickel mineral particles are removed from the surfaces by dissolving at an acidic pH, and the oppositely charged magnesium silicates yield agglomerates. 10

2. A method as set forth in claim 1, wherein the positively charged magnesium silicate matter contains serpentine and/or amphibole, and/or the negatively charged magnesium silicate matter contains talc and/or chlorite. 15

3. A method as set forth in claim 2, wherein the positively charged magnesium silicate matter contains serpentine and/or that the negatively charged magnesium silicate matter contains talc.

4. A method as set forth in claim 1, wherein the removed magnesium silicate is 20 allowed to decompose.

5. A method as set forth in any one of claims 1-4, wherein the feasibility of a concentrate for processing in terms of enrichment engineering is further improved by means of flotation. 25

6. A method as set forth in any one of claims 1-5, wherein the ore has been milled to a grain size range of D 50 = 10 pm +/- 5 pm.

7. A method of making up and treating sulfidic nickel concentrates which contain 30 magnesium silicates, substantially as herein described with reference to the accompanying examples. SPEC-816753.docx