High-purity sulfur-containing active nickel particles and a method for preparing the same

Abstract

The application discloses high-purity sulfur-containing active nickel particles and a preparation method thereof. A nickel sulfur / nickel compound is added into a nickel melt, and refining is carried out under electromagnetic stirring to obtain a nickel sulfur melt. Then, the nickel sulfur melt is cast in a mold to obtain a high-purity nickel sulfur ingot. The ingot is subjected to hot isostatic pressing to obtain a compacted blank. The blank is cut according to the size of a finished product to obtain the high-purity sulfur-containing active nickel particles. The nickel sulfur / nickel compound is selected from one of a nickel block wrapped with a nickel sulfur compound, a nickel foil wrapped with a nickel sulfur compound and a nickel sintered body containing a nickel sulfur compound. The application adds sulfur into nickel by a specific method through vacuum induction smelting, and realizes preparation of a nickel sulfur ingot with high-purity composition, stable sulfur content and no segregation by combining with electromagnetic stirring in the whole process. Subsequently, a targeted processing technology is adopted according to the large brittleness of the nickel sulfur to complete batch production of the high-purity sulfur-containing active nickel particles. The preparation method is low in comprehensive cost, small in environmental pollution and suitable for industrialized production.

Description

Technical Field

[0001] This invention belongs to the field of electroplating, specifically relating to a high-purity sulfur-containing active nickel particle and its preparation method. Background Technology

[0002] In my country's nickel plating industry, electrolytic nickel is mainly used as the anode material, while foreign countries have been using sulfur-containing active nickel since the 1960s. Sulfur-containing active nickel has attracted widespread attention in the nickel plating industry due to its advantages such as high activity, ability to be used at higher current densities, and low residue.

[0003] The main component of sulfur-containing active nickel is nickel, and the sulfur content is usually no more than 300 ppm. Excessive addition will cause severe embrittlement of nickel and deterioration of its activity. Compared with electrolytic nickel, sulfur-containing active nickel has the following advantages: (1) It can be used at higher current densities and will not passivate. It has high anode efficiency and good coating quality; (2) It has high dissolution activity; (3) It has high activity. The anode can start to dissolve at a relatively negative potential. The starting voltage of the electroplating tank is low, which saves energy; (4) It reduces copper pollution. The residue after electroplating of sulfur-containing active nickel is nickel sulfide, which can react with copper ions in the electroplating solution to form copper sulfide precipitate; (5) It has less residue, which saves metallic nickel and reduces plating solution pollution; (6) It does not produce a sponge-like structure when dissolved, which ensures the continuity of the electroplating process. As an important electroplating industrial material, sulfur-containing active nickel is mainly used as a basket electroplating anode in the electroplating process. That is, the sulfur-containing active nickel anode is placed in the electroplating basket for electroplating. Therefore, the product form is mostly a block form that is easy to fill, such as cake, crown, bead, etc. The purity and sulfur content of sulfur-containing active nickel anodes affect the peak current density of dissolution, the amount of residue generated, and the anode utilization efficiency. Generally, the higher the purity of sulfur-containing active nickel anodes in the electroplating basket and the smaller the fluctuation of sulfur content, the more stable the electroplating process, the less residue is generated, and the higher the anode utilization rate.

[0004] Currently, sulfur-containing active nickel products mainly take the form of nickel cakes (also known as nickel buckles), nickel crowns, and nickel beads. The primary preparation method is electrolysis, resulting in low product purity and difficulty in accurately controlling sulfur content and size specifications. With the continuous improvement and development of electroplating nickel technology, and the increasing demands on nickel plating quality, sulfur-containing nickel beads, cakes, and crowns, with their low purity, unstable sulfur content, irregular shapes, and rough surfaces, are gradually failing to meet the needs of the electroplating nickel industry. Compared to ordinary sulfur-containing nickel cakes, crowns, and beads, high-purity sulfur-containing nickel particles have higher purity, more stable sulfur content, and more uniform size and shape. During electroplating, they are less prone to bridging and voids within the basket, resulting in more stable and uniform anode deposition, significantly improving the quality of the nickel plating layer.

[0005] High-purity sulfur-containing active nickel particles, as a new sub-category of sulfur-containing active nickel products, can be applied in multiple fields such as batteries, electroplating, stainless steel, and alloys. Currently, the market demand for high-purity sulfur-containing active nickel particles is extremely high. For example, a domestic new energy company has an annual demand of approximately 10 tons of high-purity sulfur-containing active nickel particles, and this demand is increasing year by year. However, very few companies currently possess the capability to produce high-purity sulfur-containing active nickel particles, resulting in a supply shortage in the overall market. Patents and literature related to sulfur-containing active nickel products mainly focus on the preparation of sulfur-containing nickel cakes, nickel crowns, and nickel beads; no patents related to the preparation of high-purity sulfur-containing active nickel particles have been found.

[0006] The patent with publication number CN 101209494A discloses a method for preparing sulfur-containing nickel beads. The method involves passing a mixed gas consisting of nickel carbonyl vapor, carbon monoxide, and hydrogen sulfide (or carbonyl sulfide) into a decomposer. After heating the nickel beads, they are placed in the decomposer, where the mixed gas and nickel beads form a countercurrent contact. By controlling the heating temperature and the pressure of the decomposer, the metallic nickel and sulfur produced by the decomposition of nickel carbonyl and hydrogen sulfide (or carbonyl sulfide) in the mixed gas are deposited on the surface of the nickel beads, ultimately obtaining nickel beads with a certain amount of sulfur on the surface.

[0007] The literature "Preparation of Sulfur-Containing Active Nickel Clips for Special Electroplating Industries" describes a method for preparing nickel clips. The specific process involves using a purified nickel solution as the electrolyte in a nickel sulfate and nickel chloride mixture. Appropriate amounts of sulfur dopant (TS) and additive (SB) are added as a fresh electrolyte. A nickel sulfide anode is used as the soluble anode, and a stainless steel plate is used as the cathode. A specific electrolysis regime is applied for diaphragm electrolysis. During electrolysis, nickel is deposited on the conductive surface of the cathode plate, and the sulfur dopant is deposited on the cathode through physical adsorption and electrodialysis, achieving the purpose of sulfur doping of the nickel clips. After the production cycle is completed, the cathode is removed from the plating tank, and the nickel clips are peeled off. A special rinsing agent is used to perform surface treatment on the nickel clips, finally obtaining sulfur-containing active nickel clips.

[0008] Patent CN 101063210 B describes a process for manufacturing highly active nickel cakes using nickel-containing waste as raw material. First, the nickel and soluble substances in the recycled nickel are dissolved, and the insoluble precipitate is filtered out. Next, a precipitant is added to remove impurities such as Fe, Cu, and Zn from the solution. Then, the solution is subjected to deep impurity removal and extraction. Soda ash solution is added to adjust the pH, and the precipitate is filtered and washed to prepare nickel carbonate. Finally, an electrolyte is prepared using the above substances. The current is increased multiple times over a production cycle of 3-15 days using nickel cake plates and nickel plates containing 0.02% copper as cathodes and anodes, respectively, to finally obtain highly active nickel cakes for electroplating.

[0009] The paper "Preparation of Sulfur-Containing Active Nickel Crowns by a New Process" introduces a process for preparing nickel crowns. This process uses a high-sulfur-content nickel plate as the anode and a specially made stainless steel plate as the cathode, utilizing electrolysis to prepare sulfur-containing active nickel crowns. Specifically, a purified electrolyte containing a certain amount of additives is added to the cathode diaphragm. As the electrolysis process proceeds, crown-shaped sulfur-containing active nickel gradually precipitates on the cathode. After peeling, rinsing and surface treatment yield the sulfur-containing active nickel crowns.

[0010] Patent application publication number CN 110078137 A describes a method for preparing nickel sulfide electrode material, the main steps of which include powder preparation, sintering, and grinding. The powder preparation step first involves preparing a mixed solution containing nickel salt and sulfur-containing raw materials, followed by heating, cooling, filtering, and washing to obtain a black cake-like material. Finally, this material is subjected to ultrasonic etching to obtain a black powder material. The sintering step refers to sintering the black nickel sulfide material at high temperature, followed by final grinding to obtain the nickel sulfide electrode material.

[0011] In summary, the preparation of sulfur-containing active nickel products disclosed in existing technologies mainly relies on electrolysis. This method poses risks of environmental pollution and has high energy consumption. Furthermore, sulfur-containing active nickel products prepared by electrolysis have low purity, fluctuating sulfur content, rough surfaces, and irregular shapes. Therefore, active nickel products prepared using existing technologies are far from meeting market demand. Summary of the Invention

[0012] To address the shortcomings of existing technologies, the first objective of this invention is to provide a method for preparing high-purity sulfur-containing active nickel particles. This invention employs vacuum induction melting, adding sulfur to nickel through a specific method, combined with electromagnetic stirring throughout the process, to achieve the preparation of high-purity nickel-sulfur ingots with stable sulfur content and no segregation. Subsequently, taking advantage of the high brittleness of nickel and sulfur, hot isostatic pressing and cutting processes are used to achieve mass production of high-purity sulfur-containing active nickel particles. The preparation method of this invention has low overall cost, minimal environmental pollution, and is suitable for industrial production.

[0013] The second objective of this invention is to provide a high-purity sulfur-containing active nickel particle prepared using the above-described preparation method. The high-purity sulfur-containing active nickel particle prepared using the method of this invention has high purity, reaching 4N or higher, with minimal fluctuation in sulfur content (for example, a product with a sulfur content of 200 ppm can have its sulfur element content fluctuation controlled within ±20 ppm); furthermore, the high-purity sulfur-containing active nickel particle has a dense structure, smooth surface, and regular shape.

[0014] To achieve the above objective, the present invention adopts the following technical solution:

[0015] This invention discloses a method for preparing high-purity sulfur-containing active nickel particles. A nickel-sulfur / nickel composite is added to a nickel melt, and the melt is refined under electromagnetic stirring to obtain a nickel-sulfur melt. This melt is then cast into a mold to obtain a high-purity nickel-sulfur ingot. After hot isostatic pressing, a dense ingot is obtained. The ingot is then cut to the finished product size to obtain high-purity sulfur-containing active nickel particles. The nickel-sulfur / nickel composite is selected from one of the following: nickel blocks coated with nickel-sulfur compounds, nickel foil coated with nickel-sulfur compounds, and nickel sintered bodies containing nickel-sulfur compounds.

[0016] The preparation method of this invention differs from the electrochemical methods used in existing sulfur-containing active nickel products. It innovatively employs a smelting method to prepare high-purity sulfur-containing active nickel products. Considering that elemental sulfur has low melting and boiling points (115.21℃ and 444.72℃, respectively), far lower than the melting point of nickel (1455℃), direct addition would result in significant sulfur loss. This invention introduces sulfur into nickel by adding a nickel-sulfur / nickel composite containing or encapsulating a nickel-sulfur compound. Specifically, the nickel-sulfur compound is encapsulated in nickel blocks, nickel foil, or contained within a sintered nickel body. After the nickel is completely melted, this compound is added to the molten nickel, preventing premature exposure and thermal decomposition of the nickel-sulfur compound, which could lead to loss or the introduction of impurities. Simultaneously, continuous electromagnetic stirring throughout the vacuum smelting process ensures uniform distribution of sulfur in the ingot. This smelting process effectively guarantees high purity, stable sulfur content, and uniform distribution in the nickel-sulfur ingot. On the other hand, in view of the problem that conventional plastic deformation processing methods such as extrusion, forging, and drawing are difficult to apply to nickel-sulfur ingots, this invention first adopts hot isostatic pressing, and then cuts according to the finished size of nickel particles. This can ensure that the high-purity sulfur-containing active nickel particles have a dense structure and uniform shape and size. The remaining blanks after cutting can still be used as raw materials for the next smelting, which effectively reduces the preparation cost.

[0017] In a preferred embodiment, the high-purity sulfur-containing active nickel particles have a purity ≥4N and a sulfur content ranging from 50ppm to 300ppm, preferably 200ppm.

[0018] In a preferred embodiment, the nickel-sulfur compound is selected from at least one of NiS, NiS2, Ni3S2, and Ni9S8, with NiS2 being the most preferred.

[0019] In a preferred embodiment, the nickel-sulfur / nickel composite is a nickel block coated with a nickel-sulfur compound. In actual operation, the nickel block coated with the nickel-sulfur compound is rapidly added to the molten nickel after the nickel has completely melted. The inventors have found that compared to wrapping the nickel in nickel foil or preparing high-purity nickel sintered bodies containing nickel-sulfur compounds through powder metallurgy, wrapping the nickel-sulfur compound in a nickel block allows for faster immersion in the molten nickel, further reducing sulfur loss, and at a lower cost.

[0020] In a preferred embodiment, the nickel sintered body containing nickel-sulfur compounds is prepared by powder metallurgy.

[0021] In a preferred embodiment, the nickel melt is obtained by sequentially sandblasting, cleaning, and drying high-purity nickel and the cut nickel-sulfur residue billet, then adding the high-purity nickel and the nickel-sulfur residue billet into a crucible and melting them under vacuum conditions until melted. In this invention, the cut nickel-sulfur residue billet is the nickel-sulfur residue billet remaining after cutting the billet to the finished product size to obtain high-purity sulfur-containing active nickel particles.

[0022] Further preferred, the high-purity nickel has a purity ≥4N.

[0023] In a further preferred embodiment, the sandblasting time is 10 min to 20 min, preferably 15 min.

[0024] In a further preferred embodiment, the cleaning is performed using ultrasonic cleaning, and the cleaning medium can be selected from water, organic solvents, or semi-aqueous cleaning agents, preferably semi-aqueous cleaning agents. The ultrasonic cleaning time is 15 min to 30 min, preferably 20 min.

[0025] Further optimization involves selecting the crucible material from alumina, zirconium oxide, graphite, etc., with alumina being the preferred material.

[0026] In a further preferred embodiment, the vacuum degree is ≤10 during the smelting process for obtaining the nickel melt. -1 Pa, preferably ≤10 -2 Pa, the melting temperature is 1500℃~1600℃, preferably 1550℃.

[0027] In actual operation, corresponding preparations are made according to different methods of adding nickel-sulfur compounds. The nickel block of nickel-sulfur compound is obtained by cutting a cuboid from a nickel ingot, machining a non-through hole on the end face to accommodate the nickel-sulfur compound, and machining a nickel cylinder to fill the nickel-sulfur compound powder and then sealing the aforementioned hole. The nickel foil wrapped with nickel-sulfur compound is obtained by unfolding the nickel foil, pouring the nickel-sulfur compound powder onto one side of the nickel foil surface, rolling the nickel foil from the nickel-sulfur compound side, and finally folding up both ends to completely wrap it, avoiding leaving gaps. The nickel sintered body containing nickel-sulfur compound is obtained by weighing a certain amount of high-purity nickel powder and nickel-sulfur compound powder, mixing the powder, ball milling, adding adhesive, drying, pressing, pre-sintering, and sintering to obtain a nickel sintered body containing a certain composition of nickel-sulfur compound. Each time, a certain mass is cut and added to the melt as needed.

[0028] Based on the mass of each smelting ingot, the nickel and sulfur content in a single sulfur-nickel ingot is calculated as a percentage of sulfur mass. The raw materials include high-purity nickel (if wrapped with nickel blocks, this includes the aforementioned perforated cuboid nickel blocks and nickel cylinders), nickel foil (if wrapped with nickel foil, the nickel foil mass should be included in the raw high-purity nickel), nickel sintered body (if adding nickel to the sintered body, the nickel mass in the sintered body should be included in the raw high-purity nickel), residual nickel-sulfur billets, and nickel-sulfur compounds. Except for nickel-sulfur compounds and nickel foil, all other raw materials are pre-treated according to the aforementioned sandblasting and ultrasonic cleaning scheme, and dried before use. Nickel-sulfur compound powder is filled into the holes of the cuboid nickel blocks or wrapped with nickel foil, and the upper end of the holes in the cuboid nickel blocks is sealed with a nickel cylinder. Nickel blocks, nickel foils, or nickel sintered bodies containing nickel sulfide compounds are pre-clamped in the corresponding positions inside the vacuum induction furnace. The remaining high-purity nickel and residual nickel sulfide billets are placed in the crucible for vacuum melting. After the nickel is completely melted, nickel blocks, nickel foils, or nickel sintered bodies containing nickel sulfide compounds are added.

[0029] The preferred method is to control the vacuum level to ≤10 during refining. -1 Pa, preferably ≤10 -2 Pa, the refining temperature is 1500℃~1550℃, preferably 1520℃, and the time is 10min~30min, preferably 20min.

[0030] In a preferred embodiment, the electromagnetic stirring speed is 5 rpm to 20 rpm, preferably 10 rpm.

[0031] In a preferred embodiment, the casting temperature is 1480℃~1520℃, preferably 1500℃, and the casting rate is 0.1kg / s~0.3kg / s, preferably 0.2kg / s.

[0032] In a preferred embodiment, the casting mold is made of one of cast iron, graphite, or silicon carbide, with graphite being preferred. The inner surface of the mold is coated with a boron nitride coating, and a nickel-sulfur cooling pad is placed on the inner bottom. The mold used in this invention is a combined mold without upper and lower end faces. The inner cavity size can be adjusted as needed, and a cooling pad is placed on the inner side. The boron nitride coating serves as a high-temperature resistant lubricating coating.

[0033] In a further preferred embodiment, the cooling pad is made of nickel-sulfur. Using a nickel-sulfur cooling pad ensures that no other impurity elements are introduced during the solidification process of the molten nickel-sulfur.

[0034] In a preferred embodiment, the hot isostatic pressing (HIP) treatment is performed at a temperature of 1000℃~1200℃, preferably 1100℃, a pressure of 20MPa~40MPa, preferably 30MPa, and a time of 2h~4h, preferably 3h. Under these parameters, the HIP treatment can densify the microstructure of the high-purity nickel-sulfur ingot, which can then be cut to obtain high-purity sulfur-containing active nickel particles with a dense microstructure, smooth surface, and regular shape.

[0035] In the preferred embodiment, the process of cutting the billet to the finished product size is as follows: the billet is cut from bottom to top to obtain the billet material, the billet material is ground, and the ground billet material is then cut to the required size to obtain nickel-sulfur granules. After grinding, cleaning and drying, the final product can be obtained.

[0036] In actual operation, the ingot is sawn from bottom to top into billets of a fixed thickness until risers appear; the two cut surfaces of the billet obtained in the above steps are polished to reduce the roughness of the billet end face and further reduce the thickness of the billet; the billet is cut according to the diameter of the sulfur-containing active nickel particles, and the remaining part is reserved as raw material for the next smelting.

[0037] In a further preferred embodiment, the slitting process is as follows: the billet is sawn with a saw until a riser appears, and the thickness of the billet obtained by sawing is controlled to leave a grinding allowance of 0.2mm to 0.4mm, preferably 0.3mm, on the length of the sulfur-containing active nickel particles.

[0038] Further optimization involves placing the billet on a grinding machine and grinding both cut surfaces. Grinding reduces the roughness of the billet end faces and further thins the billet thickness, resulting in a billet thickness that matches the length of sulfur-containing active nickel particles after grinding.

[0039] Further preferably, the cutting method is selected from laser cutting, water jet cutting, and wire cutting, with water jet cutting being the preferred method.

[0040] In a preferred embodiment, the sulfur-containing active nickel particles obtained by cutting the billet to the finished size are placed in a grinding mill for grinding to remove burrs and sharp corners from the cut edges and improve the surface smoothness. The ground particles are then subjected to multiple ultrasonic cleaning cycles to remove residual dirt and impurities from the surface. After cleaning, the sulfur-containing active nickel particles are dried and vacuum packaged.

[0041] In a further preferred embodiment, the grinding machine is a horizontal grinding machine, and the abrasive is alumina spherical particles; the mass ratio of sulfur-containing active nickel particles to abrasive is 1:1~1.5, preferably 1:1.2; the total volume of sulfur-containing active nickel particles and abrasive after adding water is 85%~95% of the total volume of the grinding chamber, preferably 90%; the grinding time is 20min~40min, preferably 30min.

[0042] In a further preferred embodiment, during the multi-pass ultrasonic cleaning, the ultrasonic cleaning media are sequentially an aqueous solution containing laundry detergent, an aqueous solution containing dish soap, water, and anhydrous ethanol. The concentration of laundry detergent in the aqueous solution is 1 g / L to 3 g / L, preferably 2 g / L; the concentration of dish soap in the aqueous solution is 2 mL / L to 4 mL / L, preferably 3 mL / L; and the volume-to-mass ratio of the ultrasonic cleaning media to the particles is 2 L / kg to 4 L / kg, preferably 3 L / kg. Each ultrasonic cleaning pass takes 10 min to 30 min, preferably 20 min. Using the above steps ensures that the sulfur-containing active nickel particles are thoroughly cleaned.

[0043] In a further preferred embodiment, the drying method may be selected from at least one of constant temperature drying oven drying, natural air drying, and hot air gun drying, with hot air gun drying being preferred.

[0044] The present invention also provides a high-purity sulfur-containing active nickel particle prepared using the above method.

[0045] Principles and advantages

[0046] Sulfur-containing active nickel possesses high activity and is not easily passivated during electroplating, making it an excellent anode material for nickel plating. As market demand increases year by year, higher requirements are being placed on its purity, sulfur content stability, defect control, and shape and size. Currently, the production processes for sulfur-containing active nickel products such as nickel cakes, nickel crowns, and nickel beads are environmentally unfriendly and energy-intensive. The resulting sulfur-containing active nickel products have low purity, large fluctuations in sulfur content, rough surfaces, and irregular shapes, failing to meet the requirements for high-quality nickel plating.

[0047] This invention employs a smelting method to prepare high-purity sulfur-containing active nickel particles, resulting in low overall cost, no waste liquid generation, and minimal environmental pollution. Simultaneously, the prepared sulfur-containing active nickel particles exhibit high purity, stable sulfur content, few defects, regular shape, and uniform size. Selecting appropriate additives and adding them at the right time is crucial to ensuring high purity and stable sulfur content in sulfur-containing nickel products. This invention solves the problem of stable sulfur content control in high-purity sulfur-containing active nickel products. Considering the differences in melting point and density between nickel and sulfur, a nickel-sulfur compound is selected instead of elemental sulfur as the additive. This is achieved by pre-encapsulating the nickel-sulfur compound in nickel blocks or foils, or sintering the nickel-sulfur compound within a sintered nickel body. The nickel-sulfur / nickel composite is added after the nickel has completely melted, avoiding premature exposure and thermal decomposition of the nickel-sulfur compound, which could lead to sulfur loss or the introduction of impurities. Furthermore, continuous electromagnetic stirring throughout the smelting process ensures uniform distribution of sulfur in the ingot. This smelting process effectively guarantees high purity (4N or higher) of nickel-sulfur ingots, with stable and uniform sulfur content. On the other hand, in response to the problem that nickel-sulfur ingots are brittle and it is difficult to close internal casting defects using conventional plastic deformation processing methods such as extrusion, forging, and drawing, this invention designs processes such as hot isostatic pressing, billet sawing, and dimensional cutting to ensure that the high-purity sulfur-containing active nickel particles have a dense structure and uniform shape and size. Moreover, the residual billet after cutting can still be used as raw material for subsequent smelting, effectively reducing the preparation cost.

[0048] This invention fills the gap in the high-quality nickel plating market for the demand for high-purity, sulfur-stable active nickel particles for electroplating anodes. The technical solution has been verified in production and is feasible for batch and stable production. Attached Figure Description

[0049] Figure 1 The appearance of several sulfur-containing active nickel products currently on the market is compared with that of the sulfur-containing active nickel particles provided by this invention. As can be seen from the figures, the sulfur-containing active nickel particles obtained by the technical solution of this invention have a more regular shape, more uniform size, smoother surface, and fewer defects.

[0050] Figure 2 The appearance of the sulfur-containing active nickel particles in Example 1.

[0051] Figure 3 Example 1: Component analysis results of sulfur-containing active nickel particles.

[0052] Figure 4 The appearance of the sulfur-containing active nickel particles in Example 2.

[0053] Figure 5 Example 2: Component analysis results of sulfur-containing active nickel particles.

[0054] Figure 6 The appearance of the sulfur-containing active nickel particles in Example 3.

[0055] Figure 7 Example 3: Component analysis results of sulfur-containing active nickel particles.

[0056] Figure 8 Appearance of sulfur-containing active nickel particles in Comparative Example 2 that have not undergone hot isostatic pressing. Detailed Implementation

[0057] Example 1

[0058] High-purity sulfur-containing active nickel particles with a sulfur content of 200 ppm were prepared. Materials included 4N high-purity nickel (one piece pre-machined with holes and a nickel cylinder), residual nickel-sulfur billet, and NiS2 powder. The high-purity nickel and residual nickel-sulfur billet were sandblasted for 15 minutes, followed by ultrasonic cleaning in clean water for 20 minutes and air-drying. NiS2 powder was then filled into the holes of the nickel block, sealed with a nickel cylinder, and the entire assembly was clamped onto a robotic arm inside a vacuum induction furnace. A high-temperature resistant boron nitride coating was applied to the inner wall of a graphite mold and dried. The mold was assembled into an internal cavity with dimensions of 330 × 135 × 70 mm and placed inside the vacuum induction furnace, with a nickel-sulfur cooling pad placed at the bottom. The high-purity nickel and residual nickel-sulfur billet were added to an alumina crucible and heated under a vacuum of 10... -2 Melting was carried out under Pa at a melting temperature of 1550℃. After the nickel was completely melted, nickel blocks filled with NiS2 powder were added. Electromagnetic stirring was performed continuously during the melting process at a speed of 10 rpm. The vacuum degree during refining was 10. -2The refining process was carried out at 1520℃ for 20 minutes. After refining, the molten nickel and sulfur was poured into a graphite mold at 1500℃ and a casting rate of 0.2 kg / s. The ingot was removed after complete cooling. The ingot was then placed in a hot isostatic pressing furnace at 1100℃ and 30 MPa for 3 hours. The hot isostatically pressed ingot was then slit from bottom to top into blanks of a fixed thickness of 15.3 mm. The slit blanks were then ground on a grinding machine to a thickness of 15.0 mm on both sides. After grinding, water jet cutting was performed on the blank surface according to the diameter of 10 mm sulfur-containing active nickel particles. The resulting particles were then ground in a horizontal grinding mill with a mass ratio of sulfur-containing active nickel particles to alumina abrasive particles of 1:1.2. Water was added to fill 90% of the grinding chamber, and the grinding time was 30 minutes. The ground sulfur-containing active nickel particles were ultrasonically cleaned sequentially with an aqueous solution containing laundry detergent and an aqueous solution containing dish soap, with the ratios of laundry detergent to water being 2 g / L and 3 mL / L, respectively. The volume / mass ratio of the cleaning medium to the sulfur-containing nickel particles was 3 L / kg, and the ultrasonic cleaning time was 15 min for both. Subsequently, they were ultrasonically cleaned with clean water for 15 min, with the volume of clean water to the mass ratio of the sulfur-containing active nickel particles being 3 L / kg. Finally, they were ultrasonically cleaned in anhydrous ethanol for 10 min, removed, dried with a hot air gun, and vacuum packaged.

[0059] Figure 2 The appearance of the product obtained in Example 1, Figure 3 The results of component analysis for the product in Example 1 are shown.

[0060] The sulfur-containing active nickel particles obtained in Example 1 have regular shapes, good size consistency, and smooth, defect-free surfaces. Sampling and testing of the upper, middle, and bottom parts of the nickel-sulfur ingot confirmed that its composition met design requirements, all impurity elements were below the limit values, the sulfur content was within the design value fluctuation range, and the purity reached 4N.

[0061] Example 2

[0062] High-purity sulfur-containing active nickel particles with a sulfur content of 220 ppm were prepared. High-purity nickel ingots (4N purity), nickel foil, and NiS2 powder were prepared. The high-purity nickel ingots were sandblasted for 15 min, ultrasonically cleaned in water for 25 min, and then dried with a hot air gun. NiS2 powder was wrapped in high-purity nickel foil for later use. The inner wall of a graphite mold was coated with boron nitride paint, dried, and assembled to form an inner cavity with dimensions of 330 × 135 × 70 mm. This mold was placed in a vacuum induction furnace, with a nickel-sulfur pad placed at the bottom. High-purity nickel was added to an alumina crucible and smelted under vacuum conditions (vacuum degree 10). -2The melting temperature was 1520℃. After the nickel was completely melted, high-purity nickel foil coated with NiS2 powder was added under vacuum. Electromagnetic stirring was continuously performed during melting at a speed of 10 rpm. During refining, the vacuum level was controlled at 10... -2 The refining process was carried out at 1500℃ for 30 minutes. After refining, the molten nickel-sulfur mixture was poured into a graphite mold at 1480℃ and a casting rate of 0.3 kg / s. The ingot was removed after complete cooling. It was then placed in a hot isostatic pressing furnace at 1150℃ and 35 MPa for 3 hours. The ingot was then cut into 15.2 mm thick blanks using a saw. These blanks were then ground on a grinding machine to a thickness of 15.0 mm to reduce surface roughness. After grinding, 10 mm diameter nickel-sulfur particles were cut from the blank using a water jet cutting method. These particles were then ground in a horizontal grinding mill with a mass ratio of sulfur-containing active nickel particles to alumina abrasive particles of 1:1.2. Water was added to fill 95% of the grinding chamber, and the grinding time was 30 minutes. The ground sulfur-containing active nickel particles were ultrasonically cleaned sequentially with an aqueous solution containing laundry detergent and an aqueous solution containing dish soap, at ratios of 2 g / L and 3 mL / L to water, respectively, with a volume / mass ratio of 3 L / kg for both cleaning media and 15 min for each. They were then ultrasonically cleaned with water for 20 min, with a water volume / mass ratio of 3 L / kg for each. Finally, they were ultrasonically cleaned in anhydrous ethanol for 10 min, with an anhydrous ethanol volume / mass ratio of 2.5 L / kg for each particle. The particles were then dried using a hot air gun and vacuum-packed.

[0063] Figure 4 The appearance of the product obtained in Example 2 is shown. Figure 5 The results of component analysis for the product in Example 2 are shown.

[0064] The sulfur-containing active nickel particles obtained in Example 2 have no significant difference in appearance from the product in Example 1. They are also regular in shape, have good size consistency, smooth surface, and no defects. Their composition meets the design requirements, is high in purity, and the impurity elements do not exceed the limit. The sulfur content is within the design value fluctuation range (200ppm~240ppm).

[0065] Example 3

[0066] High-purity sulfur-containing active nickel particles with a sulfur content of 200 ppm were prepared. A rectangular nickel block was prepared, with holes drilled at one end, and a portion of the nickel was machined into nickel cylinders. Based on the mass of the nickel-sulfur ingot, the required high-purity nickel (including the drilled nickel and the nickel cylinders) and Ni3S2 powder were calculated and weighed. The high-purity nickel was sandblasted for 15 minutes, then ultrasonically cleaned in clean water for 25 minutes, and subsequently dried with a hot air gun. Ni3S2 powder was filled into the holes of the nickel block, and the nickel cylinders were used to plug the leaks. The inner wall of a graphite mold was coated with boron nitride paint, dried, and assembled to form an inner cavity with dimensions of 330 × 135 × 70 mm. A nickel-sulfur pad was placed on the bottom of the inner side, and the mold was placed in a vacuum induction furnace. High-purity nickel was added to an alumina crucible and smelted under vacuum conditions (vacuum degree 10). -2 The melting temperature was 1580℃. After the nickel was completely melted, a nickel block coated with Ni3S2 powder was added under vacuum. Electromagnetic stirring was performed throughout the melting process at a speed of 10 rpm; the vacuum level during refining was 10... -2 The refining process was carried out at 1550℃ for 30 minutes. After refining, the molten nickel and sulfur was poured into a graphite mold at 1520℃ and a casting rate of 0.1 kg / s. The ingot was removed after complete cooling. The ingot was then placed in a hot isostatic pressing furnace at 1100℃ and 30 MPa for 3 hours. The ingot was then cut into billets with a thickness of 15.4 mm using a saw. The billets obtained in the above steps were then ground on a grinding machine to a thickness of 15.0 mm. Water jet cutting was performed on the billets with a diameter of 10 mm. The resulting particles were then ground in a horizontal grinding mill with a sulfur-containing active nickel particle to alumina abrasive particle mass ratio of 1:1.3. Water was added to fill 95% of the grinding chamber, and the grinding time was 30 minutes. The ground sulfur-containing active nickel particles were ultrasonically cleaned sequentially with an aqueous solution containing laundry detergent and an aqueous solution containing dish soap, with the ratios of the two solutions to water being 2 g / L and 3 mL / L, respectively. The volume / mass ratio of the cleaning medium to the sulfur-containing nickel particles was 3 L / kg, and the ultrasonic cleaning time was 15 min for both. Subsequently, they were ultrasonically cleaned with clean water for 20 min, with the volume of clean water to the mass ratio of the sulfur-containing active nickel particles being 3 L / kg. Finally, they were ultrasonically cleaned in anhydrous ethanol for 10 min, with the volume of anhydrous ethanol to the mass ratio of the sulfur-containing active nickel particles being 2.5 L / kg. After being dried with a hot air gun, they were vacuum packaged.

[0067] Figure 6 The appearance of the product obtained in Example 3 is shown below. Figure 7 The results of component analysis for the product in Example 3 are shown.

[0068] The sulfur-containing active nickel particles obtained in Example 3 had no significant difference in appearance from the products of Examples 1 and 2, and the sulfur content was close to that of Example 1 (considering detection error). The impurity elements were all controlled below the limit, and the composition met the requirements.

[0069] Table 1 lists the purity and sulfur content range of sulfur-containing active nickel products currently on the market and sulfur-containing active nickel particles prepared using the technical solution of this invention.

[0070]

[0071] Note: The theoretical sulfur content of the sulfur-containing active nickel particles listed in Table 1 is 200 ppm.

[0072] As can be seen from the table, compared with the products of the prior art, the sulfur-containing active nickel particles provided by the present invention have higher purity, smaller fluctuations in sulfur content, and more uniform size.

[0073] Comparative Example 1

[0074] Comparative Example 1 was the same as Example 1 under the same conditions, except that the nickel-sulfur compound was not added in the form of nickel blocks, nickel foil wrapping or nickel sintered body, but was added directly after the nickel was completely melted. The sulfur content in the resulting sulfur-containing active nickel particles was far lower than the design value, which did not meet the customer's requirements.

[0075] Comparative Example 2

[0076] Comparative Example 2 was conducted under the same conditions as Example 3, except that hot isostatic pressing was not performed. The resulting sulfur-containing active nickel particles had poor surface quality and contained numerous pores. Figure 8 ).

Claims

1. A method for preparing high-purity sulfur-containing active nickel particles, characterized in that: The nickel-sulfur / nickel composite is added to the nickel melt and refined under electromagnetic stirring to obtain the nickel-sulfur melt. Then, it is cast into a mold to obtain a high-purity nickel-sulfur ingot. After hot isostatic pressing, a dense billet is obtained. The billet is cut according to the finished product size to obtain high-purity sulfur-containing active nickel particles. The nickel-sulfur / nickel composite is a nickel block coated with a nickel-sulfur compound. The nickel-sulfur compound is selected from at least one of NiS, NiS2, Ni3S2, and Ni9S8; During refining, the vacuum level should be controlled to be ≤10. -1 Pa, the refining temperature is 1500℃~1550℃, and the time is 10min~30min; The casting temperature is 1480℃~1520℃, and the casting rate is 0.1kg / s~0.3kg / s; The hot isostatic pressing treatment is performed at a temperature of 1000℃~1200℃, a pressure of 20MPa~40MPa, and a time of 2h~4h. The purity of the high-purity sulfur-containing active nickel particles is ≥4N, and the sulfur content ranges from 50ppm to 300ppm.

2. The method for preparing high-purity sulfur-containing active nickel particles according to claim 1, characterized in that: The method for obtaining the nickel melt is as follows: high-purity nickel and cut nickel-sulfur residue billet are successively sandblasted, cleaned and dried. Then, high-purity nickel and nickel-sulfur residue billet are added to a crucible and melted under vacuum conditions. The high-purity nickel has a purity ≥4N; The sandblasting time is 10 min to 20 min; The cleaning is performed using ultrasonic cleaning. The cleaning medium is selected from at least one of water, organic solvent, and semi-aqueous cleaning agent. The ultrasonic cleaning time is 15 min to 30 min. The crucible material is selected from one of alumina, zirconium oxide, and graphite; During the smelting process for obtaining the nickel melt, the vacuum degree is ≤10. -1 Pa, the melting temperature is 1500℃~1600℃.

3. The method for preparing high-purity sulfur-containing active nickel particles according to claim 1 or 2, characterized in that: The mold material is selected from one of cast iron, graphite, and silicon carbide. The inner surface of the mold is coated with boron nitride, and a nickel-sulfur cooling pad is placed on the bottom of the inner side.

4. The method for preparing high-purity sulfur-containing active nickel particles according to claim 1 or 2, characterized in that: The process of cutting the billet into finished product size is as follows: the billet is cut from bottom to top to obtain billet material, the billet material is ground, and then the ground billet material is cut into nickel-sulfur granules according to the required size. After grinding, cleaning and drying, the final product can be obtained. The slitting process is as follows: the billet is sawn with a saw until the riser appears, the thickness of the billet obtained by sawing is controlled, and a grinding allowance of 0.2mm to 0.4mm is reserved on the length of the sulfur-containing active nickel particles; Place the blank on a grinding machine and grind the two cut surfaces; The cutting method is selected from one of laser cutting, water jet cutting, and wire cutting.

5. The method for preparing high-purity sulfur-containing active nickel particles according to claim 1 or 2, characterized in that: After the billet is cut to the finished size, the sulfur-containing active nickel particles are put into a grinding machine for grinding. The ground particles are then subjected to multiple ultrasonic cleaning cycles. After cleaning, the sulfur-containing active nickel particles are dried and vacuum packaged. The grinding machine is a horizontal grinding machine, and the grinding abrasive is alumina spherical particles; the mass ratio of sulfur-containing active nickel particles to abrasive is 1:1~1.5, the total volume of sulfur-containing active nickel particles and abrasive after adding water is 85%~95% of the total volume of the grinding chamber, and the grinding time is 20min~40min. During the multi-pass ultrasonic cleaning, an aqueous solution containing laundry detergent, an aqueous solution containing dish soap, water, and anhydrous ethanol are used sequentially as ultrasonic cleaning media. The concentration of laundry detergent in the aqueous solution is 1 g / L to 3 g / L, the concentration of dish soap in the aqueous solution is 2 mL / L to 4 mL / L, the volume-to-mass ratio of the ultrasonic cleaning media to the particles is 2 L / kg to 4 L / kg, and the ultrasonic cleaning time is 10 min to 30 min. The drying method is selected from at least one of the following: drying in a constant temperature drying oven, natural air drying, and drying with a hot air gun.

6. A high-purity sulfur-containing active nickel particle prepared by the preparation method according to any one of claims 1-5.

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