A process for the sulphidization of copper-nickel sulphide lean ores

Abstract

The application provides a sulfidation method for copper-nickel sulfide lean ore and relates to the technical field of ore resource utilization. The sulfidation method for copper-nickel sulfide lean ore provided by the application comprises the following steps: mixing copper-nickel sulfide lean ore powder, a sulfidation agent, sodium salt and carbon, and sequentially performing one-stage sulfidation roasting, temperature rising and two-stage sulfidation roasting under a protective atmosphere to obtain copper-nickel sulfide lean ore containing metallic sulfide phases; the metallic sulfide phases comprise copper sulfide phases, nickel sulfide phases and cobalt sulfide phases. The sulfidation is performed by adopting a staged roasting mode, so that the oxidation phases of Ni, Co and Cu and the silicate phases in the ore can be subjected to sulfidation reaction to generate corresponding sulfides, the sulfidation rate of Ni, Co and Cu is high, the obtained copper-nickel sulfide lean ore containing metallic sulfide phases can be used to recover valuable metals by a traditional 'flotation method', and thus the problems of difficult flotation operation of oxides and silicate phases in the copper-nickel sulfide lean ore, poor concentrate quality and low recovery rate can be solved.

Description

Technical Field

[0001] This invention belongs to the field of mineral resource utilization technology, specifically relating to a sulfidation method for copper-nickel sulfide lean ore. Background Technology

[0002] Currently, the main mineral processing technology is flotation. Flotation has advantages such as wide application, high separation efficiency, and easy operation. However, the oxide phase and silicate phase in the ore are difficult to float, resulting in low metal recovery rate and high metal content in the tailings, which leads to resource waste and generates a large amount of tailings, which not only occupies a lot of land but also pollutes the environment.

[0003] The main leaching processes for metals in the oxide and silicate phases include pressure acid leaching, atmospheric pressure acid leaching, ammonia leaching, and biometallurgical processes. Among them, pressure acid leaching is highly efficient and produces high-purity products, but it has poor adaptability to raw materials and is not suitable for processing low-grade minerals. Atmospheric pressure acid leaching and pressure ammonia leaching have advantages such as high efficiency, strong adaptability to raw materials, and simple operation, but they require efficient separation of valuable metals from the leachate again, resulting in long process flows. Biometallurgy is an effective method for processing complex polymetallic minerals, with advantages such as strong operability, low cost, and low environmental pollution, but it has low metal leaching efficiency, long leaching cycle, and cannot process large quantities.

[0004] The copper-nickel sulfide lean ore in a certain area is a thick mixed ore zone located between the primary nickel sulfide lean ore and the upper oxide ore zone. It is characterized by high gangue mineral content, low metallic mineral content, high occupancy of oxide phase, and complex ore structure and intergrowth relationship. Nickel and copper elements in the ore mainly exist in the form of sulfide minerals such as nickel pyrite, purpurite, chalcopyrite, chalcopyrite, trace amounts of makinoite, goethite, and chalcopyrite. According to the classification standard of non-ferrous metal ore type, it is a mixed copper-nickel sulfide ore (copper-nickel sulfide ore). However, the oxide phase and silicate phase in this ore are difficult to float, resulting in low metal recovery rate during the flotation process. Summary of the Invention

[0005] In view of the problems in the prior art, the purpose of this invention is to provide a sulfidation method for copper-nickel sulfide lean ore. The sulfidation method provided by this invention has a high sulfidation rate of copper, nickel and cobalt in copper-nickel sulfide lean ore, and can significantly improve the recovery rate of copper, nickel and cobalt in subsequent copper-nickel sulfide lean ore.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A sulfidation method for copper-nickel sulfide lean ore includes the following steps: mixing copper-nickel sulfide lean ore powder, sulfiding agent, sodium salt, and carbon to obtain a mixture; subjecting the mixture to a first-stage sulfidation roasting, heating, and a second-stage sulfidation roasting under a protective atmosphere to obtain copper-nickel sulfide lean ore containing metallic sulfide phases; wherein the metallic sulfide phases include copper sulfide phases, nickel sulfide phases, and cobalt sulfide phases.

[0008] Furthermore, the proportion of powder with a particle size <74μm in the copper-nickel sulfide lean ore powder is 80-90wt%.

[0009] Furthermore, the sulfiding agent includes sulfur and / or pyrite.

[0010] Furthermore, the mass of the sulfiding agent is 0-4% of the mass of the copper-nickel sulfide lean ore powder, but not 0%.

[0011] Furthermore, the sodium salt includes sodium sulfate and / or sodium carbonate.

[0012] Furthermore, the mass of the sodium salt is 0-20% of the mass of the copper-nickel sulfide lean ore powder, but not 0.

[0013] Furthermore, the mass of the carbon is 0 to 4% of the mass of the copper-nickel sulfide lean ore powder, and is not 0.

[0014] Furthermore, the process conditions for the first stage of sulfurization roasting are: roasting temperature of 300℃~1000℃ and holding time of 30min~150min.

[0015] Furthermore, the process conditions for the two-stage sulfurization roasting are: roasting temperature of 850℃~1100℃ and holding time of 30min~150min.

[0016] Furthermore, after the mixture is compressed into tablets, it is subjected to a first-stage vulcanization roasting, a heating process, and a second-stage vulcanization roasting under a protective atmosphere.

[0017] The beneficial technical effects of this invention are as follows: This invention mixes copper-nickel sulfide lean ore powder, a sulfiding agent, sodium salt, and carbon, and sequentially performs a first-stage sulfidation roasting, followed by heating and a second-stage sulfidation roasting under a protective atmosphere to obtain copper-nickel sulfide lean ore containing metallic sulfide phases; the metallic sulfide phases include copper sulfide phases, nickel sulfide phases, and cobalt sulfide phases. This invention employs a staged roasting method for sulfidation, enabling the sulfidation reaction of the oxide phases of Ni, Co, and Cu, as well as the silicate phases, in the ore to generate corresponding sulfides. The sulfidation rates of Ni, Co, and Cu are high. The resulting copper-nickel sulfide lean ore containing metallic sulfide phases can recover valuable metals using the traditional "flotation method," thus solving the problems of difficult flotation operation, poor concentrate quality, and low recovery rate of oxides and silicate phases in copper-nickel sulfide lean ore. Furthermore, it can significantly improve the recovery rates of Ni, Co, and Cu in subsequent flotation processes. Attached Figure Description

[0018] Figure 1 The images show the backscattered image and energy spectrum of nickel pyrite, where (a) is the backscattered image and (b) is the energy spectrum.

[0019] Figure 2The diagram shows the intergrowth relationships of pyrite and ferritin, where (a) is a diagram showing the intergrowth of pyrite and ferritin, and (b) is a diagram showing the intergrowth of pyrite and magnetite.

[0020] Figure 3 The images show the backscattered image and energy spectrum of sulphite, where (a) is the backscattered image of the ore and (b) is the energy spectrum.

[0021] Figure 4 Diagram showing the intergrowth of sulfide and magnesite;

[0022] Figure 5 The images show the backscattered emission and energy dispersive spectroscopy (EDS) spectra of chalcopyrite, where (a) is the backscattered emission image and (b) is the energy dispersive spectroscopy (EDS).

[0023] Figure 6 The diagram shows the intergrowth of chalcopyrite, where (a) shows the intergrowth of chalcopyrite with serpentine and magnetite, and (b) shows the intergrowth of chalcopyrite with calcite.

[0024] Figure 7 The images show the backscattered image and energy spectrum of pyrite, where (a) is the backscattered image of the ore and (b) is the energy spectrum.

[0025] Figure 8 This is a particle size distribution diagram of the main sulfide minerals in low-grade copper-nickel sulfide ores.

[0026] Figure 9 This is a flowchart of the vulcanization process;

[0027] Figure 10 This is a flowchart of chemical phase analysis.

[0028] Figure 11 The graph shows the effect of sulfur addition on the occupancy of the sulfide phase.

[0029] Figure 12 The graph shows the effect of carbon powder addition on the occupancy of the sulfide phase.

[0030] Figure 13 The graph shows the effect of sodium carbonate addition on the occupancy of the sulfide phase.

[0031] Figure 14 This is a graph showing the effect of a certain sulfidation roasting time on the occupancy of the sulfidated phase.

[0032] Figure 15 The graph shows the effect of the two-stage sulfidation roasting temperature on the occupancy of the sulfidized phase.

[0033] Figure 16 The graph shows the effect of the two-stage sulfidation roasting time on the occupancy of the sulfidated phase.

[0034] Figure 17 This is a flow chart of the flotation process;

[0035] Figure 18 The graph shows the relationship between the standard Gibbs free energy and temperature for reactions 1 to 4.

[0036] Figure 19 The graph shows the relationship between the standard Gibbs free energy and temperature for reactions 5 to 8.

[0037] Figure 20 This is a diagram showing the dominant region of CuO-SC.

[0038] Figure 21 This is a map showing the dominance region of CoO-SC.

[0039] Figure 22 This is a diagram showing the dominant region of NiO-SC. Detailed Implementation

[0040] This invention provides a sulfidation method for copper-nickel sulfide lean ore, comprising the following steps: mixing copper-nickel sulfide lean ore powder, sulfiding agent, sodium salt, and carbon to obtain a mixture; subjecting the mixture to a first-stage sulfidation roasting, heating, and a second-stage sulfidation roasting under a protective atmosphere to obtain copper-nickel sulfide lean ore containing a metallic sulfide phase; wherein the metallic sulfide phase includes a copper sulfide phase, a nickel sulfide phase, and a cobalt sulfide phase.

[0041] In this invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art.

[0042] In this invention, the copper-nickel sulfide lean ore powder is preferably obtained by crushing and screening copper-nickel sulfide lean ore. This invention does not have specific limitations on the crushing and screening processes; the proportion of copper-nickel sulfide lean ore powder with a particle size ≤74μm is 80-90wt%, more preferably 85-90wt%. In this invention, the copper-nickel sulfide lean ore preferably includes copper-nickel sulfide lean ore from a specific location. This ore is characterized by the presence of Ni, Co, and Cu primarily in sulfide phases, but also containing a large amount of oxide and silicate phases, which are unfavorable for the flotation recovery of metal elements.

[0043] In this invention, the sulfiding agent preferably includes sulfur and / or pyrite, more preferably sulfur or pyrite, and even more preferably sulfur. In this invention, the mass of the sulfiding agent is 0-4% of the mass of the copper-nickel sulfide ore powder, but not 0%, more preferably 1-4%, even more preferably 2-4%, and most preferably 3-4%. In this invention, if the amount of the sulfiding agent is too small, sulfidation will be incomplete; if the amount is too large, it will waste sulfiding agent resources and easily generate SO2, polluting the atmosphere.

[0044] In this invention, the sodium salt preferably includes sodium sulfate and / or sodium carbonate, more preferably sodium sulfate or sodium carbonate, and even more preferably sodium sulfate. In this invention, the mass of the sodium salt is 0-20% of the mass of the copper-nickel sulfide lean ore powder, but not 0%, more preferably 5-15%, even more preferably 8-12%, and most preferably 10%. In this invention, if the amount of sodium salt is too small, the olivine phase in the copper-nickel sulfide lean ore powder will not be completely dissociated; if the amount is too large, reverse desulfurization will occur, leading to a decrease in the sulfidation rate of copper, nickel, and cobalt.

[0045] In this invention, the mass of carbon is preferably 0-4% of the mass of copper-nickel sulfide lean ore powder, more preferably 1-4%, further preferably 1-3.5%, and most preferably 2-3%. In this invention, using too little carbon powder will result in SO2 in the product, polluting the air and wasting the sulfiding agent, while using too much will result in waste of carbon resources.

[0046] The present invention does not have any special limitation on the mixing, as long as the raw materials are mixed evenly, such as by stirring.

[0047] After mixing, the mixture is further compressed into tablets. The present invention does not have any special limitations on the temperature, time and pressure of the tableting, as long as the mixture can be compressed into tablets. Specifically, when the mass of the copper-nickel sulfide lean ore powder is 10g, the tableting temperature is preferably room temperature, the pressure is preferably 20MPa and the time is preferably 30min.

[0048] In this invention, the protective atmosphere preferably includes nitrogen, argon, or helium. The flow rate of the protective atmosphere is preferably 150–300 mL / min, more preferably 200–250 mL / min.

[0049] In this invention, the temperature of the first-stage vulcanization roasting is 300-1000°C, more preferably 300-400°C, and the heating rate from room temperature to the first-stage vulcanization roasting temperature is preferably 3-10°C / min, more preferably 5-8°C / min; the holding time of the first-stage vulcanization roasting is preferably 30-150 min, more preferably 50-130 min, and even more preferably 100-120 min, starting from the time the temperature reaches the first-stage vulcanization roasting temperature.

[0050] In this invention, the heating rate from the temperature of the first stage of sulfurization roasting to the temperature of the second stage of sulfurization roasting is preferably 3 to 10 °C / min, more preferably 5 to 8 °C / min.

[0051] In this invention, the preferred temperature for the two-stage sulfidation roasting is 850–1100°C, more preferably 900–1050°C, and even more preferably 950–1000°C; the preferred holding time for the two-stage sulfidation roasting is 30–150 min, more preferably 50–130 min, and even more preferably 100–120 min. In this invention, the equipment used for the first-stage and second-stage sulfidation roasting is not particularly limited; roasting equipment well-known to those skilled in the art can be used. In a specific embodiment of this invention, the first-stage and second-stage sulfidation roasting are preferably carried out in a high-temperature tube furnace. This invention employs a staged roasting method for sulfidation, enabling the oxidized phases of Ni, Co, and Cu in the ore, as well as the silicate phases, to undergo sulfidation reactions to generate corresponding sulfides. The high sulfidation rate significantly improves the recovery rate of Ni, Co, and Cu in subsequent flotation processes.

[0052] Following the two-stage sulfidation roasting, the present invention further includes cooling the resulting roasted product to room temperature and then crushing it to obtain a copper-nickel sulfide lean ore containing a metallic sulfide phase. The present invention does not have any particular limitation on the cooling process; any cooling method well-known to those skilled in the art can be used, such as natural cooling. The present invention also does not have any particular limitation on the crushing process, as long as the particle size of the copper-nickel sulfide lean ore containing the metallic sulfide phase is ≤74μm.

[0053] In this invention, the metal sulfide phase in the copper-nickel sulfide lean ore containing the metal sulfide phase includes a nickel sulfide phase, a cobalt sulfide phase, and a copper sulfide phase. The content of the nickel sulfide phase is preferably 70-95 wt% (i.e., the mass of nickel in the nickel sulfide phase is the proportion of the total mass of nickel in the copper-nickel sulfide lean ore), the content of the cobalt sulfide phase is preferably 60-80 wt%, and the content of the copper sulfide phase is preferably 90-99 wt%.

[0054] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0055] Example 1

[0056] The raw material for copper-nickel sulfide ore powder: A certain enterprise's low-grade copper-nickel sulfide ore is a thick mixed ore zone located between primary nickel sulfide ore and the upper oxide ore zone. Its characteristics include high gangue mineral content, low metallic mineral content, high occupancy of oxide phase, and complex ore structure. Nickel and copper elements in the ore mainly exist in the form of sulfide minerals in nickel pyrite, purpurite, chalcopyrite, chalcopyrite, trace amounts of makinoite, goethite, and chalcopyrite. According to the classification standard of non-ferrous metal ore type, it is a mixed copper-nickel sulfide ore (copper-nickel sulfide ore).

[0057] (1) Chemical analysis of raw ore

[0058] The proportion of low-grade copper-nickel sulfide ore crushed to ≤74μm was 80-90wt%. The obtained low-grade copper-nickel sulfide ore powder was subjected to X-ray fluorescence spectrometry elemental analysis, and the results are shown in Table 1.

[0059] Table 1. Elemental analysis results of X-ray fluorescence spectra of low-grade copper-nickel sulfide ore powder

[0060] content(%) 53.762 18.593 3.511 14.572 1.368 0.8129 element Ni <![CDATA[K2O]]> Cu <![CDATA[Na2O]]> Cr Mn content(%) 0.4843 0.3625 0.3436 0.1452 0.2613 0.1245 element Ti P Co Zn Ba CaO content(%) 0.1569 0.03522 0.01465 0.01040 0.01448 3.371 element Sr V Zr Cl La Cs content(%) 0.00945 0.00823 0.00410 0.00448 0.00149 0.00139 element Rb Pb Sc Ce Y U content(%) 0.00188 0.00101 0.002075 0.00096 0.000705 0.000585 element Nb Mo As Pr Hf Ga content(%) 0.00045 0.000105 0.0002 0.000255 0.000105 0.00055 element Th Bi Br Ag Ge content(%) 0.000325 0.000175 0.00012 0.000005 0.000035

[0061] As shown in Table 1, nickel, copper and cobalt all reach the industrial utilization grade. There are a total of 6 metallic elements with a content of more than 1% in the ore, and a total of 14 elements with a content of more than 0.1%.

[0062] (2) Ore phase analysis

[0063] Low-grade copper-nickel sulfide ores are characterized by complex composition, numerous associated components, and intricate intergrowth features, making accurate identification and characterization difficult using traditional testing methods. Therefore, this invention utilizes the internationally advanced Automated Mineral Analysis System (AMICS) to analyze and test mineral samples, overcoming the limitations of conventional techniques in quantitative mineral identification and characterization.

[0064] (2.1) Mineral composition

[0065] The mineral composition of low-grade copper-nickel sulfide ores is shown in Table 2:

[0066] Table 2 Mineral composition of low-grade copper-nickel sulfide ores

[0067]

[0068]

[0069] Table 2 shows that the main constituent minerals in low-grade copper-nickel sulfide ore are serpentine (50.19 wt%) and chlorite (11.14 wt%), along with significant amounts of amphibole (7.35 wt%), olivine (4.32 wt%), and enstatite (2.76 wt%), indicating a diverse range of minerals. The main metallic minerals are magnetite and pyrite, with contents of 3.31 wt% and 2.65 wt%, respectively. Ni-containing minerals include pyrite (0.80 wt%) and trace amounts of sulphite, while Cu-containing minerals are primarily chalcopyrite (0.37 wt%).

[0070] (2.2) Characteristics of important mineral chemical composition

[0071] (2.2.1) Nickel pyrite

[0072] Nickel pyrite has the chemical formula (Fe,Ni)9S8, occurs as euhedral to subhedral granules, has a hardness of 3–4, and a density of 4.5–5.0 g / cm³. 3 Dissociation development, its backscattering image and energy spectrum are as follows: Figure 1 As shown, where, Figure 1 (a) is the backscattering diagram and (b) is the energy spectrum diagram. The energy spectrum data are shown in Table 3, and the dissociation of nickel pyrite is shown in Table 4.

[0073] Table 3 Chemical composition of nickel pyrite

[0074]

[0075]

[0076] Depend on Figure 1 As shown in Table 3, the normalized average content of Ni is 37.30%, the normalized average content of Fe is 27.06%, the content of S is 33.67%, and the particles contain a small amount of Co, with an average content of 1.12%.

[0077] Table 4. Liberation of Nickel Pyrite

[0078]

[0079] As shown in Table 4, nickel pyrite has no single liberated particles, and most of the particles are in a low degree of freedom state with a degree of liberation of less than 25%.

[0080] The intergrowth relationship of nickel pyrite, such as Figure 2 As shown, the continuous growth situation is as follows Figure 2 As shown, (a) is an intergrowth of pyrite and nickel pyrite, and (b) is an intergrowth of pyrite and magnetite. Figure 2 It is known that nickel pyrite mainly occurs in multiple associated formations with minerals such as serpentine, magnetite, and pyrite.

[0081] (2.2.3) Sulphite

[0082] The chemical composition of sulphite is NiS2, with a hardness of 4.5–5.5 and a density of approximately 4.45 g / cm³. 3 The backscattered image and energy spectrum of sulphite are as follows: Figure 3 As shown in Table 5, (a) is the backscattering diagram of the ore and (b) is the energy spectrum diagram. The energy spectrum data are shown in Table 5, and the liberation of the sulfide nickel ore is shown in Table 6.

[0083] Table 5 Chemical composition of sulfide nickel ore

[0084] S / wt% 48.37 50.15 49.82 49.95 49.66 49.59 Ni / wt% 45.77 43.93 45.35 44.28 43.99 44.66 Fe / wt% 5.07 5.34 3.95 4.90 5.69 4.99 Co / wt% 0.79 0.57 0.88 0.86 0.66 0.75

[0085] Depend on Figure 3 As shown in Table 5, the nickel content in the sulphite is relatively high, with an average value of 44.66%, and the average sulfur content is 49.59%. The particles generally contain a small amount of Fe (4.99%) and a trace amount of Co (0.75%).

[0086] Table 6. Liberation of Nickel Sulfide Ore

[0087]

[0088] Table 6 shows that sulphite contains no single liberated particles, and over 70% of the particles are in a low-degree-of-freedom state with a degree of liberation of less than 25%. The intergrowth of sulphite is complex, mainly occurring in multiple associations with minerals such as serpentine, pyrite, and magnesite. Among these, the association of sulphite with magnesite is particularly prominent. Figure 4 As shown.

[0089] (2.2.3) Chalcopyrite

[0090] Chalcopyrite has the chemical composition CuFeS2, a hardness of 3–4, and a density of 4.1–4.3 g / cm³. 3 Its backscattering image and energy spectrum are as follows: Figure 5 As shown in Table 7, (a) is the backscattering diagram of chalcopyrite, and (b) is the energy spectrum diagram. The energy spectrum data are shown in Table 7, and the dissociation of chalcopyrite is shown in Table 8.

[0091] Table 7 Chemical composition of chalcopyrite

[0092] S / wt% 33.01 34.58 33.92 34.28 34.09 33.98 Fe / wt% 32.51 33.09 32.39 33.93 32.41 32.87 Cu / wt% 34.48 32.33 33.68 31.79 33.50 33.16

[0093] Depend on Figure 5 As shown in Table 7, the normalized average content of Cu is 33.16%, the normalized average content of Fe is 32.87%, and the content of S is 33.98%.

[0094] Table 8. Liberation of Chalcopyrite

[0095]

[0096]

[0097] Table 8 shows that chalcopyrite contains no single liberated particles, and more than 50% of the particles are in a low degree-of-freedom state with a degree of liberation ranging from 0% to 25%. The intergrowth is quite complex, mainly consisting of multiple intergrowths with serpentine, magnetite, pyrite, and other minerals. The intergrowth of chalcopyrite with serpentine and magnetite is as follows: Figure 6 As shown in (a), the intergrowth of chalcopyrite and calcite is as follows: Figure 6 As shown in (b).

[0098] (2.2.4) Pyrite

[0099] Pyrite has the chemical composition FeS2, occurs in anhedral granular form, has no cleavage, a hardness of 6, and a density of approximately 4.90 g / cm³. 3 It is non-magnetic, and its backscattering image and energy spectrum are as follows: Figure 7 As shown in Table 9, (a) is the backscattering diagram of the ore and (b) is the energy spectrum diagram. The energy spectrum data are shown in Table 9 and the separation situation is shown in Table 10.

[0100] Table 9 Chemical composition of pyrite

[0101] S / wt% 51.20 50.55 49.64 50.54 51.04 50.59 Fe / wt% 48.80 49.45 50.36 49.46 48.96 49.41

[0102] Depend on Figure 7 As shown in Table 9, the normalized average content of Fe in pyrite is 49.41%, and the average content of S is 50.59%.

[0103] Table 10 Pyrite Liberation Status

[0104]

[0105] As shown in Table 10, the degree of liberation of individual pyrite particles is low, only 0.22%, and nearly 50% of the particles are in a low degree of freedom state with a degree of liberation in the range of 0 to 25%. The intergrowth is relatively complex, mainly consisting of multiple intergrowths with minerals such as serpentine and pyrrhotite.

[0106] (2.2.5) Grain size distribution characteristics of sulfide minerals

[0107] The particle size distribution of the major rare earth minerals, bastnaesite and monazite, was analyzed using the Automated Mineral Quantitative Analysis System (AMICS). The results are as follows: Figure 8 As shown. By Figure 8It can be seen that the average particle size of pyrite is smaller than that of the other three minerals, with 80% of the total minerals having a particle size of less than 180 μm and 50% having a particle size of less than 38 μm. The particle size distribution characteristics of nickel pyrite, sulphite, and chalcopyrite are similar, with particle sizes all less than 125 μm. This indicates that if the degree of liberation of niobium minerals in the concentrate is to be increased, the grinding fineness can be appropriately increased during the beneficiation test.

[0108] (3) Chemical phase analysis of Ni, Co and Cu in low-grade copper-nickel sulfide ores

[0109] The main nickel mineral phases in low-grade copper-nickel sulfide ores are pyrite and sulphite, accounting for approximately 1% of the total. Nickel in pyrite accounts for about 32.50% of the total nickel in the ore, and nickel in sulphite accounts for about 33.50%, together making up 66.0% of the total nickel in the ore. Furthermore, the nickel oxidation rate is high, with nickel oxide content at 0.12%, accounting for 22.6% of the total nickel in the ore, existing as secondary nickel oxides, which are generally dispersed, poorly crystallized, or amorphous. Simultaneously, almost all silicate minerals contain varying amounts of nickel, with nickel silicate content at 0.06%, accounting for 11.3% of the total nickel in the ore. Therefore, nickel that cannot be effectively recovered from the ore accounts for 33.9% of the total nickel in the ore.

[0110] Copper in the ore mainly exists as chalcopyrite (including chalcopyrite) and a small amount of chalcopyrite, with no other copper minerals observed. Copper content in other metallic minerals is low, and the amount of copper dispersed in non-metallic minerals is also extremely small. Copper accounts for 78.52% of the total copper in chalcopyrite. In addition, copper in pyrite, nickel pyrite, and sulphite accounts for approximately 2.01% of the total copper in the ore. This portion of copper will enter the concentrate along with pyrite, nickel pyrite, and sulphite, where the theoretical copper recovery rate can reach 80.53%.

[0111] Cobalt in the ore is mainly dispersed in isomorphous forms in metallic sulfides such as nickel pyrite, chalcopyrite, and pyrite, accounting for about 70% of the total cobalt in the ore. This portion of cobalt will be enriched in the concentrate. Cobalt is highly correlated with nickel, so about 30% of the cobalt is located in the oxide and silicate phases, making it difficult to float into the concentrate.

[0112] Example 2

[0113] use Figure 9The process flow diagram shown illustrates the sulfidation process, with the specific steps as follows: Low-grade copper-nickel sulfide ore from a certain enterprise is crushed and screened to a particle size ≤74μm, comprising 80-90wt% of low-grade copper-nickel sulfide ore powder. The low-grade copper-nickel sulfide ore powder, sulfur, sodium sulfate, and carbon powder are taken. The amount of low-grade copper-nickel sulfide ore powder is 10g, the amount of sulfur added is 4% of the mass of the low-grade copper-nickel sulfide ore powder, the amount of sodium sulfate added is 10% of the mass of the low-grade copper-nickel sulfide ore powder, and the amount of carbon powder added is 2% of the mass of the low-grade copper-nickel sulfide ore powder. The low-grade copper-nickel sulfide ore powder, sulfur, sodium sulfate, and carbon powder are mixed evenly and heated at room temperature (25℃) and 20M... The product was statically pressed for 30 min under Pa conditions, placed in a ceramic boat, and then placed in a high-temperature tube furnace. The temperature was increased to 400℃ at a rate of 5℃ / min, followed by a first-stage sulfidation roasting for 120 min. Then, the temperature was increased to 1000℃ for a second-stage sulfidation roasting for 120 min. During the roasting process, nitrogen gas was introduced at a flow rate of 200 mL / min. The furnace was cooled to room temperature, and the roasted product was crushed to a particle size of -74 μm to obtain a copper-nickel sulfide lean ore containing metallic sulfide phases. The content and proportion of silicate phases, oxide phases, and sulfide phases of Ni, Co, and Cu in the copper-nickel sulfide lean ore containing metallic sulfide phases were analyzed.

[0114] The analytical procedure for the chemical phase occupancy rate is as follows: Figure 10 As shown, the specific method is as follows:

[0115] (1) Determination of the sulfide phase: 60 mL of saturated bromine water was added to a glass beaker containing 0.2 g of sample, shaken for 60 min at room temperature, filtered, and the residue and filtrate were obtained; the filtrate was heated on a heating plate to evaporate to 25 mL, 5 mL of 68 wt% hydrochloric acid was added, heated to boiling, cooled to room temperature, transferred to a 100 mL volumetric flask and diluted to volume, and tested using an inductively coupled plasma atomic emission spectrometer (Thermo Fisher Scientific, ICP-7400).

[0116] (2) Determination of silicate phase: The residue obtained in step (1) was placed together with filter paper into an Erlenmeyer flask, and 60 mL of 5 wt% perchloric acid solution was poured in. The mixture was heated to 100 °C in a water bath and kept at that temperature for 60 min. After cooling to room temperature, the mixture was filtered to obtain the residue and filtrate. The filtrate was heated on a heating plate to evaporate to a small volume and then transferred to a 100 mL volumetric flask and diluted to a final volume. The mixture was then tested using an inductively coupled plasma atomic emission spectrometer (Thermo Fisher Scientific, ICP-7400).

[0117] (3) Determination of the oxidized phase: The residue obtained in step (2) and the filter paper were placed in a beaker and placed in a muffle furnace. The beaker was calcined at 400°C for 60 minutes in an air atmosphere. After cooling to room temperature, 30 mL of 38 wt% concentrated nitric acid and 10 mL of sulfuric acid solution (98 wt% concentrated sulfuric acid to water volume ratio = 1:1, to prevent liquid splashing) were added. Note that if black carbon appears in the beaker during this process, concentrated nitric acid needs to be added and splashing should be prevented. After the filter paper is completely dissolved, the beaker was evaporated and cooled. The beaker wall was rinsed with deionized water. 5 mL of 68 wt% hydrochloric acid was added, heated to boiling, and then cooled to room temperature. The mixture was transferred to a 100 mL volumetric flask and diluted to volume. The test was performed using an inductively coupled plasma atomic emission spectrometer (Thermo Fisher Scientific, ICP-7400).

[0118] Examples 3-25

[0119] Copper-nickel sulfide lean ore containing metal sulfide phases was prepared by sulfidation according to the method of Example 1, and the sulfidation conditions are shown in Table 11.

[0120] Table 11. Vulcanization conditions of Examples 1-25 and Comparative Examples 1-3

[0121]

[0122]

[0123] The test results of the content and occupancy of silicate phase, oxide phase and sulfide phase of Ni, Co and Cu in copper-nickel sulfide lean ores containing metal sulfide phases prepared in Examples 1-25 and Comparative Examples 1-3 are as follows: Figures 11-16 As shown in Table 12, where Figure 11 The effect of sulfur addition on the occupancy of the sulfide phase. Figure 12 The effect of carbon powder addition on the occupancy of the sulfide phase; Figure 13 The effect of sodium carbonate addition on the occupancy of the sulfide phase; Figure 14 The effect of a sulfidation roasting time on the occupancy of the sulfided phase; Figure 15 The effect of the two-stage sulfidation roasting temperature on the occupancy of the sulfidized phase; Figure 16 The effect of the two-stage sulfidation roasting time on the occupancy of the sulfidized phase.

[0124] Table 12 shows the test results of the content and occupancy of Ni, Co, and Cu silicate phases, oxide phases, and sulfide phases in copper-nickel sulfide lean ores containing metal sulfide phases prepared in Examples 1-25 and Comparative Examples 1-3.

[0125]

[0126]

[0127]

[0128]

[0129]

[0130]

[0131]

[0132] From Table 12 and Figure 11 It can be seen that the proportion of sulfide phases of cobalt, copper, and nickel first increases and then tends to stabilize with the increase of sulfur addition. The proportion of sulfide phases of copper and nickel reaches the highest when the sulfur addition is 4%, at 98.69% and 92.15%, respectively; the proportion of sulfide phases of cobalt reaches the highest at 3%, at 77.64%.

[0133] From Table 12 and Figure 12 It can be seen that the proportion of cobalt, copper and nickel sulfide phases first increases and then tends to stabilize with the increase of carbon powder addition. The proportion of cobalt, copper and nickel sulfide phases reaches the highest when the carbon powder addition is 3%, which is 76.61%, 97.87% and 94.23%, respectively.

[0134] From Table 12 and Figure 13 It can be seen that the proportions of cobalt and nickel sulfide phases first increase and then decrease with the increase of sodium carbonate addition, while the proportion of copper sulfide phase continues to increase slowly even when the sodium carbonate addition exceeds 10%. The proportions of cobalt and nickel sulfide phases are highest when the sodium carbonate addition is 10%, at 79.4% and 93.7% respectively, while the proportion of copper sulfide phase is highest at 20% sodium carbonate addition, at 98.76%.

[0135] From Table 12 and Figure 14 It can be seen that the proportion of cobalt, copper and nickel sulfide phases first decreases, then increases and then decreases again with the increase of a sulfide roasting time. When the sulfide roasting time is 120 min, the proportion of cobalt, copper and nickel sulfide phases is the highest, at 69.48%, 96.82% and 90.59% respectively.

[0136] From Table 12 and Figure 15 It can be seen that the proportion of cobalt, copper and nickel sulfide phases first increases and then decreases with the increase of the two-stage sulfidation roasting temperature. When the two-stage sulfidation roasting temperature is 1050℃, the proportion of cobalt, copper and nickel sulfide phases is the highest, at 79.56%, 97.83% and 94.02% respectively.

[0137] From Table 12 and Figure 16It can be seen that the proportion of cobalt, copper and nickel sulfide phases first decreases and then decreases with the increase of the two-stage sulfide roasting time. When the first-stage sulfide roasting time is 120 min, the proportion of cobalt, copper and nickel sulfide phases is the highest, at 81.31%, 98% and 95.19% respectively.

[0138] Example 26

[0139] The copper-nickel sulfide lean ore containing metal sulfide phases prepared in Example 8 and the copper-nickel sulfide lean ore without sulfide roasting were subjected to flotation under the same flotation conditions. The flotation process flow diagram is shown below. Figure 17 As shown, the specific steps of flotation are as follows:

[0140] (1) The copper-nickel sulfide lean ore containing metal sulfide phase prepared in Example 8 and the copper-nickel sulfide lean ore without sulfide roasting were ground in a sample preparation machine to a fineness of -0.074 mm and a proportion of 80-90 wt% to obtain mineral powder.

[0141] (2) Take 150g of mineral powder and place it in a single-cell flotation machine. Add 6g of MIBC (4-methyl-2-pentanol), 22.5g of butyl xanthate, 60g of sodium hexametaphosphate and 30g of Cu2SO4 in sequence. Stir with air at a rate of 200mL / min for 3min and then float for 12min. Dry the obtained flotation concentrate and flotation tailings to constant weight and weigh them. Analyze the content of Ni, Co and Cu in the concentrate by ICP. The content of cobalt, copper and nickel in the flotation concentrate and the recovery rate of cobalt, copper and nickel are shown in Table 13.

[0142] Table 13. Contents of cobalt, copper, and nickel in the concentrate and their recovery rates.

[0143]

[0144] As shown in Table 13, pretreatment using the sulfidation method provided by this invention followed by flotation can significantly improve the recovery rates of cobalt, copper, and nickel in copper-nickel sulfide lean ores.

[0145] Example 27

[0146] Thermodynamic analysis of reaction during sulfidation roasting (single-stage sulfidation roasting and two-stage sulfidation roasting)

[0147] (1) Reactions that occur during sulfurization roasting

[0148] Thermodynamic analysis was performed on the possible reactions (reactions 1 to 8) during the sulfidation roasting process, verifying the thermodynamic feasibility of the sulfidation reaction. Figure 18 The graph shows the standard Gibbs free energy versus temperature for reactions 1 through 4. Figure 19 The graph shows the relationship between the standard Gibbs free energy and temperature for reactions 5 to 8.

[0149] 2CoO + S² + C = 2CoS + CO₂ (Reaction 1)

[0150] 2NiO + S² + C = 2NiS + CO₂ (Reaction 2)

[0151] 2CuO + S²⁺ + C = 2CuS + CO₂ (Reaction 3)

[0152] 2MgO + S²⁺ + C = 2MgS + CO₂ (Reaction 4)

[0153] 2Co₂SiO₄ + 3Na₂CO₃ = Na₆Si₂O₇ + 4CoO + 3CO₂ (Reaction 5)

[0154] Co₂SiO₄ + Na₂CO₃ = Na₂SiO₃ + 2CoO + 2CO₂ (Reaction 6)

[0155] 2Ni₂SiO₄ + 3Na₂CO₃ = Na₆Si₂O₇ + 4NiO + 3CO₂ (Reaction 7)

[0156] 2Ni₂SiO₄ + Na₂CO₃ = Na₂Si₂O₅ + 4NiO + CO₂ (Reaction 8)

[0157] Depend on Figure 18 It can be seen that when the sulfidation roasting temperature is between 200 and 1400 K, the standard Gibbs free energy of reactions 1 to 4 is less than zero, indicating that the sulfidation reaction can proceed. Furthermore, the sulfidation reactions of Ni, Co, and Cu are all superior to those of Mg, which suggests that only a small amount of Mg will enter the subsequent flotation process, thus reducing the adverse effects of Mg on the flotation process.

[0158] Depend on Figure 19 It can be seen that when the sulfidation roasting temperature is between 1000 and 1400 K, the standard Gibbs free energy of reactions 5 to 8 is less than zero. This indicates that when the sulfidation roasting temperature is above 1000 K, nickel silicate and cobalt silicate can react with sodium carbonate to generate nickel oxide and cobalt oxide, which are then sulfided into nickel sulfide and cobalt sulfide.

[0159] (2) Analysis of the dominance zones of Ni, Co and Cu and thermodynamic analysis of pyrite reaction

[0160] To investigate the occurrence and valence states of Ni, Cu, and Co during sulfidation roasting, the dominance regions of Ni, Cu, and Co in a sulfidation atmosphere at roasting temperatures ranging from 200 to 1200 °C were calculated, as shown in the figure. Figures 20-22 As shown, where, Figure 20 This is a diagram showing the dominant region of CuO-SC. Figure 21 This is a map showing the dominance region of CoO-SC. Figure 22 This is a diagram showing the dominant region of NiO-SC. (Source: [Insert Source Here]) Figures 20-22 It can be seen that when P(O2) = 10 -20 At 1050 °C, Cu remains stable in the range of 200–1200 °C for copper sulfides; Co remains stable in the range of 200–1200 °C for cobalt sulfides. However, when the temperature exceeds 1050 °C, the sulfur partial pressure is less than 10. -4 At atm, a stable region for Co appears; Ni is in the stable region of nickel sulfides from 200 to 1200℃. There are many types of nickel sulfides, and Ni3S2 is stable at high temperatures.

[0161] In summary, the nickel oxide phase in the copper-nickel sulfide lean ore in the embodiments is generally dispersed, poorly crystallized, or non-crystallized. The ore is pretreated by a "step-by-step sulfidation roasting" process, using sulfur as the sulfiding agent, sodium salt as the additive, and carbon powder as the reducing agent. The first stage of sulfidation roasting is carried out below the boiling point of the sulfiding agent or near its decomposition temperature, and then the temperature is raised to the set temperature for the second stage of sulfidation roasting. This process can destroy the crystal structure of the silicate phase in the ore, allowing Ni, Co, and Cu metal elements to be released in the form of oxides. The staged roasting process also causes the oxide phases of Ni, Co, and Cu in the ore and the silicate phase to sulfide and generate the corresponding sulfides. The sulfidation rate is high, which creates favorable conditions for flotation.

[0162] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A sulfidation method for copper-nickel sulfide lean ore, characterized in that, Includes the following steps: Copper-nickel sulfide lean ore powder, sulfiding agent, sodium salt, and carbon are mixed to obtain a mixture. The mixture is then subjected to a first-stage sulfidation roasting, heating, and a second-stage sulfidation roasting under a protective atmosphere to obtain copper-nickel sulfide lean ore containing metallic sulfide phases. The metallic sulfide phases include copper sulfide phases, nickel sulfide phases, and cobalt sulfide phases. The mass of the sulfiding agent is 3-4% of the mass of the copper-nickel sulfide lean ore powder; The sodium salt is 10-20% of the mass of the copper-nickel sulfide lean ore powder; The mass of carbon is 2 to 4% of the mass of copper-nickel sulfide lean ore powder.

2. The sulfidation method for copper-nickel sulfide lean ore according to claim 1, characterized in that, The proportion of powder with a particle size ≤74μm in the copper-nickel sulfide lean ore powder is 80~90wt%.

3. The sulfidation method for copper-nickel sulfide lean ore according to claim 1, characterized in that, The sulfiding agent includes sulfur and / or pyrite.

4. The sulfidation method for copper-nickel sulfide lean ore according to claim 1, characterized in that, The sodium salt includes sodium sulfate and / or sodium carbonate.

5. The sulfidation method for copper-nickel sulfide lean ore according to any one of claims 1 to 4, characterized in that, The process conditions for the first stage of sulfurization roasting are: roasting temperature of 300℃~1000℃ and holding time of 30min~150min.

6. The sulfidation method for copper-nickel sulfide lean ore according to claim 1, characterized in that, The process conditions for the two-stage vulcanization roasting are: roasting temperature of 850℃~1100℃ and holding time of 30min~150min.

7. The sulfidation method for copper-nickel sulfide lean ore according to claim 1 or 6, characterized in that, After the mixture is compressed into tablets, it is subjected to a first-stage vulcanization roasting, a temperature rise, and a second-stage vulcanization roasting under a protective atmosphere.

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