Low nickel matte grinding and floating process for improving copper-nickel recovery

Abstract

This invention discloses a low-nickel matte grinding and flotation process to improve copper-nickel recovery, comprising the following steps: S1, grinding; S2, roughing treatment; S3, cleaning treatment; S4, scavenging treatment; S5, regrinding and re-selecting the middlings; S6, merging the first concentrate from step S3 with the second concentrate from step S5 to obtain the final copper-nickel concentrate. This low-nickel matte grinding and flotation process utilizes a specially modified collector, combined with a closed-loop process of roughing-scavenging-middling regrinding and re-selection, and a differentiated step-by-step reagent dosing system, to achieve efficient and synergistic recovery of copper and nickel metals from low-nickel matte. The process flow is complete, and the process parameters at each stage are reasonably matched. While ensuring the acquisition of high-grade copper-nickel concentrate, it minimizes the loss of valuable metals in the tailings, significantly improving the final copper-nickel recovery rate. The overall technical effect is superior to traditional flotation methods using a single collector or simple mixed reagents.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology, specifically relating to a low-nickel matte grinding and flotation process to improve copper-nickel yield. Background Technology

[0002] Low-nickel matte is an important intermediate product in the nickel pyrometallurgical process, typically obtained from nickel concentrate or laterite nickel ore through reduction smelting and matte-making smelting. It mainly consists of sulfides of nickel, copper, iron, cobalt, and other metals, with a small amount of intermetallic compounds. The iron content is relatively high, while the nickel grade is relatively low, hence the name low-nickel matte. As a core raw material for subsequent refining and purification to produce high-purity electrolytic nickel, electrolytic copper, and other products, how to economically and efficiently separate and enrich copper and nickel in low-nickel matte is a key link and technical challenge in the entire nickel smelting process.

[0003] Currently, the grinding-flotation process is widely used in industry to process low-nickel matte to separate copper and nickel concentrates. However, when processing low-nickel matte, especially low-nickel matte with high iron content, traditional flotation separation methods generally face a series of technical bottlenecks. First, the mineral phase composition formed during the cooling process of low-nickel matte is complex. Copper and nickel sulfides are often closely associated with iron sulfides and are finely embedded. Conventional grinding is insufficient to achieve sufficient individual liberation, resulting in copper and nickel minerals being unable to be effectively recovered during flotation due to being encapsulated by gangue or iron sulfides. This leads to high tailings grades and unsatisfactory metal recovery rates. Second, the floatability of copper and nickel sulfides is not significantly different during flotation, and under certain reagent regimes, iron sulfides are easily activated and float, interfering with the effective separation of copper and nickel, making it difficult to guarantee the quality of the concentrate product.

[0004] To overcome the aforementioned shortcomings, existing technologies have explored various approaches. One major direction for improvement is the development and application of novel flotation reagents, particularly collectors, to enhance the selective collection of copper and nickel sulfides. For example, this involves physically combining multiple known collectors or making simple functional group modifications to the molecular structure of traditional collectors (such as xanthates and dioxins) to enhance their selective adsorption capacity for target minerals. Another direction for improvement is adjusting the flotation process flow, such as increasing the number of cleaning cycles to improve concentrate grade or extending the flotation time to increase recovery.

[0005] While existing technologies have improved the separation performance of low-nickel matte to some extent through the aforementioned improvements, their inherent technical shortcomings remain significant. Regarding reagents, simple physical compound reagents have independent mechanisms of action among their components in the pulp, making it difficult to produce a synergistic enhancement effect and resulting in limited overall selectivity improvement. Simple chemical modifications to traditional collectors often only enhance a single collecting function without fundamentally changing their interaction pattern with the minerals. When facing low-nickel matte with complex surface properties and close intergrowth relationships, their selectivity and collecting capacity remain insufficient, making it difficult to adapt to fluctuations in ore properties. In terms of process flow, simply increasing the number of cleaning cycles inevitably sacrifices recovery rate for grade, while blindly extending flotation time increases reagent consumption and production costs, and may cause some suppressed impurities to float back to the surface, worsening the separation effect.

[0006] Therefore, developing a flotation process that can efficiently match the selectivity and capacity for collecting copper-nickel sulfides to achieve efficient recovery of copper-nickel resources from low-nickel matte remains a pressing technical challenge in this field. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this invention is to provide a low-nickel matte grinding and floating process to improve the copper-nickel yield.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A low-nickel matte grinding and floating process for improving copper-nickel yield includes the following steps: S1. The large pieces of low-nickel matte are crushed to obtain mineral powder, which is then added to a mill for wet grinding to obtain slurry. S2. Add the slurry from step S1 into the flotation machine, then add the modified collector, frother and pH adjuster to adjust the pH, and carry out roughing treatment to obtain rough concentrate and roughing tailings. S3. Add the rough concentrate from step S2 to the flotation machine for fine cleaning to obtain the first concentrate and the fined tailings; S4. Add the roughing tailings from step S2 into the flotation machine, then add the modified collector and perform scavenging treatment to obtain scavenged concentrate and final tailings. S5. Combine the selected tailings from step S3 and the scavenged concentrate from step S4 into middlings, and after regrinding, add the modified collector again for re-selection to obtain the second concentrate. S6. Combine the first concentrate from step S3 with the second concentrate from step S5 to obtain the final copper-nickel concentrate.

[0009] Preferably, the grinding fineness of the mineral powder in step S1 is 85-95% of the particles being -75μm, and after grinding, the slurry is adjusted in a slurry conditioning tank so that the mass concentration of the slurry entering step S2 is 30-40%.

[0010] In this invention, copper-nickel sulfides encased in low-nickel matte minerals are released by mechanical force through crushing and grinding, exposing the mineral surface. The grinding fineness is controlled at -75μm, accounting for 85-95%, which ensures the effective adsorption of the modified collector and is the basis for improving the copper-nickel yield.

[0011] Preferably, the foaming agent in step S2 is one or both of pine oil and methyl isobutyl methanol, and its addition amount is 20-30 g / t based on the mass of low-nickel matte.

[0012] Preferably, the modified collector described in step S2 is prepared as follows: Trimethylolpropane tris(3-mercaptopropionic acid) ester was added to ethanol, followed by the addition of 2-vinylpyridine and azobisisobutyronitrile. The mixture was heated to react, and after the reaction was completed, the ethanol was removed by rotary evaporation to obtain product A. Product A was added to acetonitrile, followed by the addition of ethyl chloroacetate. The mixture was then reacted at a constant temperature, and after the reaction was completed, the solvent was removed by rotary evaporation. The product was then washed and dried to obtain the modified collector.

[0013] Preferably, the mass ratio of trimethylolpropane tris(3-mercaptopropionic acid), 2-vinylpyridine, and azobisisobutyronitrile is 30:24-27:0.5-0.8, and the heating reaction is carried out at a temperature of 60-70°C for 5-8 hours.

[0014] In this invention, the modified collector is made from trimethylolpropane tris(3-mercaptopropionic acid) ester and 2-vinylpyridine. Trimethylolpropane tris(3-mercaptopropionic acid) ester is a star-shaped, three-dimensional molecule with three symmetrically distributed long arms, each with a thiol group at the end. Its star-shaped structure and long carbon chain, once adsorbed onto the mineral surface, can form a three-dimensional, fluffy hydrophobic layer, greatly enhancing the hydrophobicity of the mineral particles and making them easily adhere to bubbles and float. The vinyl group in 2-vinylpyridine has high chemical reactivity and can undergo addition reactions. The nitrogen atom on the pyridine ring is both an auxiliary collecting group that coordinates with metal ions and an active site for subsequent reactions. Through the click chemical reaction between the vinyl group of 2-vinylpyridine and the thiol group of trimethylolpropane tris(3-mercaptopropionic acid) ester, the main collecting group (S), the auxiliary collecting group (N), and the hydrophobic framework are combined to form a multifunctional product A.

[0015] Preferably, the mass ratio of product A to ethyl chloroacetate is 50:26-31, the isothermal reaction temperature is 70-80℃, and the time is 12-16h.

[0016] In this invention, product A is reacted with ethyl chloroacetate. Ethyl chloroacetate, as a quaternizing agent, can attack the N atom of the pyridine ring on product A. After the reaction, the N atom forms a positively charged quaternary ammonium salt center, introducing cationic charge to the collector molecule. On the one hand, the introduction of the quaternary ammonium salt center significantly improves the solubility and dispersion of the collector in the aqueous phase, allowing it to be more evenly distributed in the slurry, thus having the opportunity to effectively contact more mineral particles and improving the utilization efficiency of the reagent. On the other hand, copper-nickel sulfides usually have a negatively charged surface in alkaline flotation slurry. Due to the electrostatic attraction between positive and negative charges, the collector molecules are preferentially and rapidly adsorbed onto the surface of copper-nickel minerals, greatly improving the adsorption selectivity and kinetic rate, and reducing ineffective consumption on gangue.

[0017] In the final modified collector molecule, S and N atoms are chemically bonded at a suitable spatial distance. When it encounters copper-nickel sulfides, these two atoms can simultaneously coordinate with the same metal ion to form a stable five- or six-membered ring (chelate). Compared to single-atom adsorption, the adsorption force of this chelation effect is much higher, ensuring that the collector can firmly grasp the mineral and is not easily detached under the scouring of the slurry. Furthermore, the three-dimensional star-shaped framework provided by trimethylolpropane tris(3-mercaptopropionic acid) ester forms a three-dimensional hydrophobic layer on the mineral surface, which can more effectively repel water molecules, has a larger contact angle with bubbles, and adheres more firmly, thereby significantly improving the stability and flotation efficiency of mineralized bubbles, and ultimately achieving a high recovery rate of copper-nickel metal from low-nickel matte.

[0018] Preferably, the slurry concentration in the roughing treatment in step S2 is 30-40%, and the amount of modified collector added is 40-60 g / t based on the mass of low-nickel matte; the pH adjuster is sodium hydroxide, and the pH value is 9.5-11.

[0019] In this invention, the roughing process is carried out at a high pulp concentration (30-40%). By using a modified collector, all floatable copper and nickel minerals are rapidly collected. The purpose of adding a pH adjuster is to create an alkaline environment (pH 9.5-11), which can effectively suppress associated iron sulfide minerals such as pyrite and improve the relative grade of copper and nickel in the concentrate.

[0020] Preferably, the slurry concentration in the fine treatment step S3 is 15-25%.

[0021] In this invention, during the roughing process, the rough concentrate is floated at a low pulp concentration (15-25%). The low concentration reduces interference between mineral particles and makes it easier for gangue impurities entrained in the froth to fall off and be washed away, thereby ensuring the quality of the first concentrate.

[0022] Preferably, the slurry concentration in step S4 is 25-35%, and the amount of modified collector added is 10-20 g / t based on the mass of low-nickel matte.

[0023] In this invention, the tailings from the roughing process are processed during the scavenging process. These tailings contain a small amount of copper-nickel minerals that are difficult to process, are associated with gangue, or failed to fully react with the reagents during the roughing stage. By supplementing a certain amount of collector (10-20 g / t), they are enhanced for recovery.

[0024] Preferably, in step S5, the fineness of the regrinding is more than 90% of the particles being -45μm, the mass concentration of the slurry being regrinded is 15-25%, and the amount of modified collector added is 20-40g / t based on the dry weight of the middlings.

[0025] In this invention, two mineral streams with similar properties, namely the selected tailings and the scavenged concentrate, are combined and regrinded (grinded to a finer consistency, with -45μm accounting for 90%) to forcibly break up the remaining intergrowths. Then, reagents are added again for re-selection, avoiding the direct return of these difficult-to-process materials to the roughing process. This stabilizes the main process and maximizes the recovery of copper and nickel through separate processing, resulting in a second concentrate.

[0026] Compared with the prior art, the present invention has the following beneficial effects: (1) The low-nickel matte grinding and flotation process for improving copper and nickel yield provided by the present invention achieves efficient and synergistic recovery of copper and nickel metals in low-nickel matte by using a specially modified collector and combining a closed-loop process of roughing-scavenging-mid-ore regrinding and re-selection with a differentiated step-by-step dosing system. The process flow is complete and the process parameters of each stage are reasonably matched. While ensuring the acquisition of high-grade copper and nickel concentrate, it minimizes the loss of valuable metals in tailings, thereby significantly improving the final copper and nickel recovery rate. The overall technical effect is better than the traditional flotation method with a single collector or a simple mixture of reagents.

[0027] (2) The low-nickel matte flotation process for improving copper-nickel yield provided by this invention uses a modified collector that firmly connects the sulfur-containing group to the nitrogen-containing heterocyclic skeleton through a mercaptoene reaction, and then introduces the cation center through a quaternization reaction. This specific molecular structure endows the modified collector with strong chelating and electrostatic adsorption capabilities. Its two active sites, S and N, are firmly bonded to the surface of copper-nickel minerals, and its adsorption selectivity and stability are far beyond those of collectors with a single active group. At the same time, a specific design was made for the flotation process, adopting a differentiated dosing system of main dosing in roughing, supplementary dosing in scavenging, and re-dosing in middlings. In the roughing stage, the main dosing is applied to the flotation process. Most of the collector (40-60 g / t) is added to ensure the full recovery of the main valuable minerals. For the trace valuable metals that are difficult to be processed or closely associated with gangue in the roughing tailings, a small amount of collector (10-20 g / t) is added during the scavenging stage for enhanced recovery. For the middlings returned from the cleaning and scavenging stages, after breaking up the intergrowths by regrinding, collector is added again (20-40 g / t) for targeted treatment. This step-by-step, on-demand dosing method precisely matches the properties of different minerals. Compared with one-time dosing, it ensures the total recovery rate and avoids excessive use of reagents, thereby improving the utilization efficiency of reagents and the economy of the process.

[0028] (3) The low-nickel matte grinding and flotation process for improving copper and nickel yield provided by the present invention has specially set a key step of middlings regrinding and re-selection to select medium-grade materials such as tailings and scavenging concentrates. These materials are characterized by containing a large number of intergrowths of target minerals and gangue. The present invention does not simply return them to the roughing system to interfere with the main process, but combines them and performs targeted secondary grinding to fully dissociate them. Then, re-selection is carried out at an optimized pulp concentration (15-25%). This approach of processing middlings separately effectively separates and recovers the difficult-to-select intergrowth particles from the main process, which not only reduces the burden of roughing and selection operations, but also saves valuable metals that should have been lost in the tailings or recycling system. It is a key link to achieve high recovery rate.

[0029] (4) This invention achieves efficient and stable operation of the flotation process by optimizing the control of pulp concentration in each flotation stage (30-40% for roughing, 15-25% for cleaning, and 25-35% for scavenging). A higher roughing concentration is beneficial to increasing the collision probability between mineral particles and collectors and bubbles, thus ensuring the recovery rate. A lower cleaning concentration provides more space to facilitate the removal of gangue minerals mixed in the foam, thereby improving the concentrate grade. A medium scavenging concentration takes into account the collection efficiency of low-grade minerals, which is an important process guarantee for achieving a balance between high grade and high recovery rate. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Unless otherwise specified, all chemical reagents and materials in this invention are purchased from the market or synthesized from raw materials purchased from the market.

[0032] In this invention, the main components of the low-nickel matte ore are: Cu 6.3%, Ni 2.7%, Fe 42.4%, S 28.5%, and Co 0.31%. Example 1

[0033] A low-nickel matte grinding and floating process for improving copper-nickel yield includes the following steps: S1. The large pieces of low-nickel matte are crushed to obtain mineral powder. The mineral powder is then added to a mill for wet grinding. The grinding fineness is -75μm particle size accounts for 90%. After grinding, the slurry is adjusted in a slurry tank to obtain a slurry with a mass concentration of 35%. S2. Add the slurry from step S1 into the flotation machine, then add the modified collector (50 g / t based on the mass of low-nickel matte) and pine oil (25 g / t based on the mass of low-nickel matte), add sodium hydroxide to adjust the pH to 10, and carry out roughing treatment to obtain rough concentrate and roughing tailings. S3. Add the rough concentrate from step S2 to the flotation machine, adjust the pulp to a pulp mass concentration of 20%, and perform fine cleaning treatment to obtain the first concentrate and fine tailings. S4. Add the roughing tailings from step S2 into the flotation machine, adjust the pulp to a pulp mass concentration of 30%, then add a modified collector (15g / t based on the mass of low-nickel matte) and perform scavenging treatment to obtain scavenged concentrate and final tailings. S5. Combine the selected tailings from step S3 and the scavenged concentrate from step S4 into middlings, and then regrind them. The fineness of the regrinded fineness is more than 90% of the particles are -45μm. After adjusting the slurry, the slurry mass concentration is 20%. Add the modified collector again (30g / t based on the dry weight of the middlings) for re-selection to obtain the second concentrate. S6. Combine the first concentrate from step S3 with the second concentrate from step S5 to obtain the final copper-nickel concentrate.

[0034] The preparation method of the modified collector in step S2 is as follows: 30g of trimethylolpropane tris(3-mercaptopropionic acid) ester was added to 500mL of ethanol, followed by 26g of 2-vinylpyridine and 0.7g of azobisisobutyronitrile. The mixture was reacted at 65℃ for 7h under a nitrogen atmosphere. After the reaction was completed, the ethanol was removed by rotary evaporation to obtain product A. 50g of product A was added to 500mL of acetonitrile, followed by 29g of ethyl chloroacetate. The mixture was reacted at 75℃ for 14h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was washed 2-3 times with diethyl ether and dried under vacuum to obtain the modified collector. Example 2

[0035] A low-nickel matte grinding and floating process for improving copper-nickel yield includes the following steps: S1. The large pieces of low-nickel matte are crushed to obtain mineral powder. The mineral powder is then added to a mill for wet grinding. The grinding fineness is -75μm particle size accounts for 85%. After grinding, the slurry is adjusted in a slurry tank to obtain a slurry with a mass concentration of 30%. S2. Add the slurry from step S1 into the flotation machine, then add the modified collector (40 g / t based on the mass of low-nickel matte) and pine oil (20 g / t based on the mass of low-nickel matte), add sodium hydroxide to adjust the pH to 9.5, and carry out roughing treatment to obtain rough concentrate and roughing tailings. S3. Add the rough concentrate from step S2 to the flotation machine, adjust the pulp to a pulp mass concentration of 15%, and perform fine cleaning to obtain the first concentrate and fine tailings. S4. Add the roughing tailings from step S2 into the flotation machine, adjust the pulp to a pulp mass concentration of 25%, then add a modified collector (10g / t based on the mass of low-nickel matte) and perform scavenging treatment to obtain scavenged concentrate and final tailings. S5. Combine the selected tailings from step S3 and the scavenged concentrate from step S4 into middlings, and then regrind them. The fineness of the regrinded fineness is more than 90% -45μm particle size. After adjusting the slurry, the slurry mass concentration is 15%. Add the modified collector again (20g / t based on the dry weight of middlings) for re-selection to obtain the second concentrate. S6. Combine the first concentrate from step S3 with the second concentrate from step S5 to obtain the final copper-nickel concentrate.

[0036] The preparation method of the modified collector in step S2 is as follows: 30g of trimethylolpropane tris(3-mercaptopropionic acid) ester was added to 500mL of ethanol, followed by 27g of 2-vinylpyridine and 0.8g of azobisisobutyronitrile. The mixture was reacted at 70℃ for 5h under a nitrogen atmosphere. After the reaction was completed, the ethanol was removed by rotary evaporation to obtain product A. 50g of product A was added to 500mL of acetonitrile, followed by 31g of ethyl chloroacetate. The mixture was reacted at 80℃ for 12h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was washed 2-3 times with diethyl ether and dried under vacuum to obtain the modified collector. Example 3

[0037] A low-nickel matte grinding and floating process for improving copper-nickel yield includes the following steps: S1. The large pieces of low-nickel matte are crushed to obtain mineral powder. The mineral powder is then added to a mill for wet grinding. The grinding fineness is -75μm particle size accounts for 95%. After grinding, the slurry is adjusted in a slurry tank to obtain a slurry with a mass concentration of 40%. S2. Add the slurry from step S1 into the flotation machine, then add the modified collector (60 g / t based on the mass of low-nickel matte) and pine oil (30 g / t based on the mass of low-nickel matte), add sodium hydroxide to adjust the pH to 11, and carry out roughing treatment to obtain rough concentrate and roughing tailings. S3. Add the rough concentrate from step S2 to the flotation machine, adjust the pulp to a pulp mass concentration of 25%, and perform fine cleaning treatment to obtain the first concentrate and fine tailings. S4. Add the roughing tailings from step S2 into the flotation machine, adjust the pulp to a pulp mass concentration of 35%, then add a modified collector (20 g / t based on the mass of low-nickel matte) and perform scavenging treatment to obtain scavenged concentrate and final tailings. S5. Combine the selected tailings from step S3 and the scavenged concentrate from step S4 into middlings, and then regrind them. The fineness of the regrinded fineness is more than 90% -45μm particle size. After adjusting the slurry, the slurry mass concentration is 25%. Add the modified collector again (40g / t based on the dry weight of middlings) for re-selection to obtain the second concentrate. S6. Combine the first concentrate from step S3 with the second concentrate from step S5 to obtain the final copper-nickel concentrate.

[0038] The preparation method of the modified collector in step S2 is as follows: 30g of trimethylolpropane tris(3-mercaptopropionic acid) ester was added to 500mL of ethanol, followed by 24g of 2-vinylpyridine and 0.5g of azobisisobutyronitrile. The mixture was reacted at 60℃ for 8h under a nitrogen atmosphere. After the reaction was completed, the ethanol was removed by rotary evaporation to obtain product A. 50g of product A was added to 500mL of acetonitrile, followed by 26g of ethyl chloroacetate. The mixture was reacted at 70℃ for 16h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was washed 2-3 times with diethyl ether and dried under vacuum to obtain the modified collector. Comparative Example 1

[0039] A low-nickel matte grinding and floating process for improving copper-nickel yield includes the following steps: S1. The large pieces of low-nickel matte are crushed to obtain mineral powder. The mineral powder is then added to a mill for wet grinding. The grinding fineness is -75μm particle size accounts for 90%. After grinding, the slurry is adjusted in a slurry tank to obtain a slurry with a mass concentration of 35%. S2. Add the slurry from step S1 into the flotation machine, then add the modified collector (50 g / t based on the mass of low-nickel matte) and pine oil (25 g / t based on the mass of low-nickel matte), add sodium hydroxide to adjust the pH to 10, and carry out roughing treatment to obtain rough concentrate and roughing tailings. S3. Add the rough concentrate from step S2 to the flotation machine, adjust the pulp to a pulp mass concentration of 20%, and perform fine cleaning treatment to obtain the first concentrate and fine tailings. S4. Add the roughing tailings from step S2 into the flotation machine, adjust the pulp to a pulp mass concentration of 30%, then add a modified collector (15g / t based on the mass of low-nickel matte) and perform scavenging treatment to obtain scavenged concentrate and final tailings. S5. Combine the selected tailings from step S3 and the scavenged concentrate from step S4 into middlings, and then regrind them. The fineness of the regrinded fineness is more than 90% of the particles are -45μm. After adjusting the slurry, the slurry mass concentration is 20%. Add the modified collector again (30g / t based on the dry weight of the middlings) for re-selection to obtain the second concentrate. S6. Combine the first concentrate from step S3 with the second concentrate from step S5 to obtain the final copper-nickel concentrate.

[0040] The preparation method of the modified collector in step S2 is as follows: 30g of trimethylolpropane tris(3-mercaptopropionic acid) ester was added to 500mL of ethanol, followed by 26g of 2-vinylpyridine and 0.7g of azobisisobutyronitrile. The mixture was reacted at 65℃ under a nitrogen atmosphere for 7h. After the reaction was completed, the ethanol was removed by rotary evaporation to obtain the modified collector.

[0041] Compared to Example 1, this comparative example did not introduce ethyl chloroacetate into the modified collector. Comparative Example 2

[0042] A low-nickel matte grinding and floating process for improving copper-nickel yield includes the following steps: S1. The large pieces of low-nickel matte are crushed to obtain mineral powder. The mineral powder is then added to a mill for wet grinding. The grinding fineness is -75μm particle size accounts for 90%. After grinding, the slurry is adjusted in a slurry tank to obtain a slurry with a mass concentration of 35%. S2. Add the slurry from step S1 into the flotation machine, then add the modified collector (50 g / t based on the mass of low-nickel matte) and pine oil (25 g / t based on the mass of low-nickel matte), add sodium hydroxide to adjust the pH to 10, and carry out roughing treatment to obtain rough concentrate and roughing tailings. S3. Add the rough concentrate from step S2 to the flotation machine, adjust the pulp to a pulp mass concentration of 20%, and perform fine cleaning treatment to obtain the first concentrate and fine tailings. S4. Add the roughing tailings from step S2 into the flotation machine, adjust the pulp to a pulp mass concentration of 30%, then add a modified collector (15g / t based on the mass of low-nickel matte) and perform scavenging treatment to obtain scavenged concentrate and final tailings. S5. Combine the selected tailings from step S3 and the scavenged concentrate from step S4 into middlings, and then regrind them. The fineness of the regrinded fineness is more than 90% of the particles are -45μm. After adjusting the slurry, the slurry mass concentration is 20%. Add the modified collector again (30g / t based on the dry weight of the middlings) for re-selection to obtain the second concentrate. S6. Combine the first concentrate from step S3 with the second concentrate from step S5 to obtain the final copper-nickel concentrate.

[0043] The preparation method of the modified collector in step S2 is as follows: 30g of trimethylolpropane tris(3-mercaptopropionic acid), 26g of 2-vinylpyridine and 29g of ethyl chloroacetate were mixed evenly to obtain the modified collector.

[0044] Compared with Example 1, the modified collector in this comparative example was prepared by physical mixing of trimethylolpropane tris(3-mercaptopropionic acid), 2-vinylpyridine and ethyl chloroacetate. Comparative Example 3

[0045] A low-nickel matte grinding and floating process for improving copper-nickel yield includes the following steps: S1. The large pieces of low-nickel matte are crushed to obtain mineral powder. The mineral powder is then added to a mill for wet grinding. The grinding fineness is -75μm particle size accounts for 90%. After grinding, the slurry is adjusted in a slurry tank to obtain a slurry with a mass concentration of 35%. S2. Add the slurry from step S1 into the flotation machine, then add the collector (50 g / t based on the mass of low-nickel matte) and pine oil (25 g / t based on the mass of low-nickel matte), add sodium hydroxide to adjust the pH to 10, and carry out roughing treatment to obtain rough concentrate and roughing tailings. S3. Add the rough concentrate from step S2 to the flotation machine, adjust the pulp to a pulp mass concentration of 20%, and perform fine cleaning treatment to obtain the first concentrate and fine tailings. S4. Add the roughing tailings from step S2 into the flotation machine, adjust the pulp to a pulp mass concentration of 30%, then add a collector (15g / t based on the mass of low-nickel matte) and perform scavenging treatment to obtain scavenged concentrate and final tailings. S5. Combine the selected tailings from step S3 and the scavenged concentrate from step S4 into middlings, and then regrind them. The fineness of the regrinded fineness is more than 90% of the particles are -45μm. After adjusting the slurry, the slurry mass concentration is 20%. Collector is added again (30g / t based on the dry weight of middlings) for re-selection to obtain the second concentrate. S6. Combine the first concentrate from step S3 with the second concentrate from step S5 to obtain the final copper-nickel concentrate.

[0046] Compared with Example 1, the collector added in this invention consists of sodium isobutyl xanthate and sodium diethyldithiocarbamate in a mass ratio of 1:1. Comparative Example 4

[0047] A low-nickel matte grinding and floating process for improving copper-nickel yield includes the following steps: S1. The large pieces of low-nickel matte are crushed to obtain mineral powder. The mineral powder is then added to a mill for wet grinding. The grinding fineness is -75μm particle size accounts for 90%. After grinding, the slurry is adjusted in a slurry tank to obtain a slurry with a mass concentration of 35%. S2. Add the slurry from step S1 into the flotation machine, then add the modified collector (50 g / t based on the mass of low-nickel matte) and pine oil (25 g / t based on the mass of low-nickel matte), add sodium hydroxide to adjust the pH to 10, and carry out roughing treatment to obtain rough concentrate and roughing tailings. S3. Add the rough concentrate from step S2 into the flotation machine, adjust the pulp to a pulp mass concentration of 20%, and perform fine cleaning to obtain the first concentrate and fine tailings. The fine tailings are returned to the rough feed in step S2. The first concentrate is the final copper-nickel concentrate. S4. Add the roughing tailings from step S2 to the flotation machine, adjust the pulp to a pulp mass concentration of 30%, then add a modified collector (15g / t based on the mass of low-nickel matte) and perform scavenging treatment to obtain scavenged concentrate and final tailings. The scavenged concentrate is returned to the roughing feed in step S2.

[0048] The preparation method of the modified collector in step S2 is as follows: 30g of trimethylolpropane tris(3-mercaptopropionic acid) ester was added to 500mL of ethanol, followed by 26g of 2-vinylpyridine and 0.7g of azobisisobutyronitrile. The mixture was reacted at 65℃ for 7h under a nitrogen atmosphere. After the reaction was completed, the ethanol was removed by rotary evaporation to obtain product A. 50g of product A was added to 500mL of acetonitrile, followed by 29g of ethyl chloroacetate. The mixture was reacted at 75℃ for 14h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was washed 2-3 times with diethyl ether and dried under vacuum to obtain the modified collector.

[0049] Compared with Example 1, this comparative example does not perform separate regrinding and re-selection of middlings, but directly adds them to the roughing process, i.e., omitting step S5.

[0050] The final copper-nickel concentrates obtained from Examples 1-3 and Comparative Examples 1-4 were measured, and the measurement results are shown in Table 1 below. Copper recovery rate = copper metal content in the final copper-nickel concentrate / copper metal content in the low-nickel matte × 100%, and nickel recovery rate = nickel metal content in the final copper-nickel concentrate / nickel metal content in the low-nickel matte × 100%.

[0051] Table 1

[0052] As can be seen from Table 1 above, the low-nickel matte grinding and flotation process for improving copper and nickel yield provided by this invention can significantly improve the recovery rate of copper and nickel. The performance of Comparative Example 1 (modified collector without quaternization) and Comparative Example 2 (raw materials in modified collector without chemical reaction) is significantly lower, proving the necessity of molecular modification and structural integration. Comparative Example 3 (using existing collectors) is the benchmark of traditional technology and is completely surpassed by the examples, proving the specific adsorption properties of the modified collector in this scheme. The performance of Comparative Example 4 (without separate treatment of middlings) also decreased, proving that the process of this invention has a significant advantage over traditional processes in terms of separate regrinding and re-selection of ore.

[0053] The above description is a further detailed explanation of the present invention in conjunction with specific implementation examples. It should not be considered that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the protection scope of the present invention.

[0054] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-nickel matte grinding and flotation process for improving copper-nickel yield, characterized in that, Includes the following steps: S1. The large pieces of low-nickel matte are crushed to obtain mineral powder, which is then added to a mill for wet grinding to obtain slurry. S2. Add the slurry from step S1 into the flotation machine, then add the modified collector, frother and pH adjuster to adjust the pH, and carry out roughing treatment to obtain rough concentrate and roughing tailings. S3. Add the rough concentrate from step S2 to the flotation machine for fine cleaning to obtain the first concentrate and the fined tailings; S4. Add the roughing tailings from step S2 into the flotation machine, then add the modified collector and perform scavenging treatment to obtain scavenged concentrate and final tailings. S5. Combine the selected tailings from step S3 and the scavenged concentrate from step S4 into middlings, and after regrinding, add the modified collector again for re-selection to obtain the second concentrate. S6. Combine the first concentrate from step S3 with the second concentrate from step S5 to obtain the final copper-nickel concentrate.

2. The low-nickel matte grinding and floating process according to claim 1, characterized in that, The grinding fineness of the mineral powder in step S1 is 85-95% of the particles being -75μm. After grinding, the slurry is adjusted in a slurry conditioning tank so that the mass concentration of the slurry entering step S2 is 30-40%.

3. The low-nickel matte grinding and floating process according to claim 1, characterized in that, The foaming agent mentioned in step S2 is one or both of pine oil and methyl isobutyl methanol, and its addition amount is 20-30 g / t based on the mass of low-nickel matte.

4. The low-nickel matte grinding and floating process according to claim 1, characterized in that, The preparation method of the modified collector in step S2 is as follows: Trimethylolpropane tris(3-mercaptopropionic acid) ester was added to ethanol, followed by the addition of 2-vinylpyridine and azobisisobutyronitrile. The mixture was heated to react, and after the reaction was completed, the ethanol was removed by rotary evaporation to obtain product A. Product A was added to acetonitrile, followed by the addition of ethyl chloroacetate. The mixture was then reacted at a constant temperature, and after the reaction was completed, the solvent was removed by rotary evaporation. The product was then washed and dried to obtain the modified collector.

5. The low-nickel matte grinding and floating process according to claim 4, characterized in that, The mass ratio of trimethylolpropane tris(3-mercaptopropionic acid), 2-vinylpyridine, and azobisisobutyronitrile is 30:24-27:0.5-0.8, and the heating reaction is carried out at a temperature of 60-70°C for 5-8 hours.

6. The low-nickel matte grinding and floating process according to claim 4, characterized in that, The mass ratio of product A to ethyl chloroacetate is 50:26-31, and the isothermal reaction is carried out at a temperature of 70-80℃ for 12-16 hours.

7. The low-nickel matte grinding and floating process according to claim 1, characterized in that, The slurry concentration in the roughing process in step S2 is 30-40%, and the amount of modified collector added is 40-60 g / t based on the mass of low-nickel matte; the pH adjuster is sodium hydroxide, and the pH value is 9.5-11.

8. The low-nickel matte grinding and floating process according to claim 1, characterized in that, The slurry concentration in the fine treatment step S3 is 15-25%.

9. The low-nickel matte grinding and floating process according to claim 1, characterized in that, The slurry concentration in step S4 is 25-35%, and the amount of modified collector added is 10-20 g / t based on the mass of low-nickel matte.

10. The low-nickel matte grinding and floating process according to claim 1, characterized in that, In step S5, the fineness of the regrinding is such that more than 90% of the particles are of -45μm size, the mass concentration of the re-selected slurry is 15-25%, and the amount of modified collector added is 20-40g / t based on the dry weight of the middlings.

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