Crushing and grinding process of high-pressure roller mill for disseminated non-uniform nickel-copper ore

Abstract

The invention discloses a high-pressure roller grinding process for non-uniformly-embedded nickel-copper ore, and aims to solve the problems of low ore grinding efficiency, high energy consumption, insufficient target mineral dissociation and influence on subsequent sorting due to easy over-grinding and argillization when the existing grinding process is used for treating the non-uniformly-embedded nickel-copper ore with high magnesium oxide content. The process of coarse crushing, intermediate crushing, two-section high-pressure roller grinding (fine crushing and superfine crushing), wet screening closed-loop circulation and ball-milling closed-loop grinding is adopted, and efficient crushing and grading of ores are achieved by controlling the roller gap of the two-section high-pressure roller grinding (the fine crushing is 22-20 mm, and the superfine crushing is 16-12 mm), the screen mesh aperture of the wet screening and ball-milling parameters. According to the process, the crushing efficiency is improved (the proportion of a superfine product with the particle size being-200 meshes is larger than or equal to 40%), the ore grinding energy consumption is reduced, mineral dissociation is optimized, the follow-up grading operation requirement is met, and the process is suitable for treating the nickel-copper sulfide ore embedded unevenly.

Description

Technical Field

[0001] This invention relates to a crushing and grinding process for nickel-copper sulfide ores, specifically to a high-pressure roller mill crushing and grinding process for treating unevenly distributed nickel-copper sulfide ores. Background Technology

[0002] With the development and widespread application of nickel metal in new energy batteries, the resource-rich sulfide nickel-copper ores have been almost exhausted. The occurrence of nickel, copper and associated precious metal minerals in nickel-copper ores is becoming increasingly complex, making ore sorting more and more difficult. It is difficult to efficiently ensure the recovery of valuable metals during mineral processing, which directly affects the economic benefits of ore beneficiation plants.

[0003] The nickel-copper ore involved in this invention has unevenly distributed nickel and copper grades of 0.55% and 0.30%, respectively, and a magnesium oxide content of 28.75%. The nickel and copper grades are low, while the MgO content is relatively high, with the majority of nickel and copper existing in the form of sulfide phases. The main nickel mineral in the ore is pyrite, followed by sulphite; the main copper mineral is chalcopyrite, with trace amounts of chalcopyrite and chalcopyrite. Other metallic minerals are mainly magnetite, followed by pyrite, with minor amounts of siderite, chromite, ilmenite, and trace amounts of hematite, limonite, pyrrhotite, sphalerite, and galena. Precious metal minerals include argentite, sterlingite, and chalcopyrite. The non-metallic minerals are mainly serpentine, followed by chlorite, tremolite, olivine, and bronzite, with minor amounts of common amphibole, talc, magnesite, albite, quartz, dolomite, spinel, and biotite, and trace amounts of diopside, potassium feldspar, calcite, apatite, sphene, grossular, and zircon. The grain size composition of the main target minerals in the nickel-copper ore is shown in Table 1.

[0004] Due to the close intermingling of nickel sulfide and copper sulfide minerals in this ore, and its complex symbiotic relationship with pyrite, a full sulfide flotation process is required to improve copper and nickel recovery. Given the complex mineral composition of the ore, the uneven particle size distribution of the target minerals, and the high content of easily mud-forming minerals such as serpentine, chlorite, and talc, the SABC process is currently employed (process flow diagram shown). Figure 1 (The particle size distribution of the semi-autogenous grinding product in the SABC process is shown in Table 3) When the semi-autogenous grinding mill is subjected to crushing and dissociation, it is constrained by the production capacity and fails to achieve the pre-dissociation of the target mineral, resulting in repeated dissociation of the ore, which causes the ore to become muddy due to over-grinding and is difficult to beneficiate in the subsequent process. Summary of the Invention

[0005] To address the problems of low grinding efficiency, high energy consumption, and insufficient mineral liberation in existing technologies for unevenly distributed nickel-copper ores, a grinding process combining two-stage high-pressure roller mills and wet screening in a closed-loop circulation is provided to improve the ore crushing ratio and the degree of liberation of the target mineral, while reducing grinding energy consumption.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A high-pressure roller mill grinding process for unevenly distributed nickel-copper ore includes the following steps: (1) Coarse crushing: The nickel-copper ore is coarsely crushed by a standard cone crusher, and the discharge opening is controlled to be 55-52mm.

[0007] The nickel-copper ore has a nickel grade of 0.55%, a copper grade of 0.30%, and a magnesium oxide content of 28.75%. The main target minerals are nickel sulfide minerals and copper sulfide minerals, and the total content of non-metallic minerals such as serpentine, chlorite, and talc is ≥40%.

[0008] (2) Medium crushing: The coarse crushed product from step (1) is subjected to medium crushing using a short-head cone crusher, with the discharge opening controlled at 25-20mm.

[0009] (3) Fine crushing: The medium crushed product from step (2) is finely crushed through a high-pressure roller mill, and the roller gap is controlled to be 22-20mm.

[0010] (4) Ultrafine crushing: The finely crushed product from step (3) is subjected to ultrafine crushing through a two-stage high-pressure roller mill, with the roller gap controlled at 16-12 mm. The ultrafine crushed product is then temporarily stored in a powder silo. The particle size distribution of the product after ultrafine crushing by the two-stage high-pressure roller mill meets the following requirements: -200 mesh particle size accounts for ≥40%.

[0011] (5) Wet screening closed-loop circulation: The ultrafine crushed products in the powder ore bin are screened by a wet screening machine. The screen mesh size is controlled at 4mm×10mm. The products on the screen are returned to the second-stage high-pressure roller mill to form a closed-loop circulation. The P80 of the products under the screen is ≤2mm.

[0012] (6) Closed-circuit ball milling: The undersize product from step (5) is mixed with water and then transported to the ball mill pump pool. The slurry is pumped into the hydrocyclone for inspection and classification. The operating pressure of the hydrocyclone is 0.08-0.10 MPa, the media filling rate of the ball mill is 30-35%, and the grinding concentration is 65-70% of the ore mass. The overflow of the hydrocyclone is used as the feed for the separation operation, and the sand is returned to the ball mill to form a closed-circuit grinding.

[0013] The beneficial effects of this invention are as follows: Compared to the SABC crushing and grinding method for nickel-copper ore, the use of cone crushing and two-stage high-pressure roller mills for ultra-fine crushing of the ore and pre-dissociation of the target minerals truly achieves "more crushing and less grinding" in mineral processing.

[0014] The process employs a two-stage high-pressure roller mill (fine crushing + ultrafine crushing), with the roller gap gradually decreasing (22-20mm → 16-12mm), increasing the ore crushing ratio to more than 1.5 times that of traditional processes. The ultrafine crushed product has a particle size of -200 mesh or more of ≥40%, which provides a favorable foundation for subsequent grinding.

[0015] By using a closed-loop wet screening process, unqualified coarse particles are returned for further crushing, avoiding over-grinding. The energy consumption of the ball milling process is reduced by 12-15 kW·h / t compared to the SABC process.

[0016] The hydrocyclone grading control (pressure 0.08-0.10MPa) is matched with the ball mill parameters (medium filling rate 30-35%, concentration 65-70%), so that the degree of liberation of nickel sulfide and copper sulfide minerals in the overflow product reaches more than 85%, which meets the requirements of the separation operation. Attached Figure Description

[0017] Figure 1 Flowchart of the SABC crushing and grinding process for nickel-copper ore; Figure 2 This is a flow chart of the high-pressure roller mill grinding process for unevenly embedded nickel-copper ore according to the present invention. Detailed Implementation

[0018] The present invention will be further described below through specific embodiments. Example

[0019] The following table shows the grain size composition of the main target minerals in nickel-copper ore: like Figure 2 As shown, the high-pressure roller mill grinding process for unevenly distributed nickel-copper ore includes the following steps: (1) The mined nickel-copper ore is transported to a standard cone crusher for coarse crushing, and the discharge opening is controlled at 52mm; (2) The product from step (1) is transported to a short-head cone crusher for medium crushing, and the discharge opening is controlled at 25mm; (3) The product from step (2) is conveyed to a high-pressure roller mill for fine crushing, with the roller gap controlled at 22mm; (4) The product from step (3) is conveyed to a two-stage high-pressure roller mill for ultrafine crushing, with the roller gap controlled at 12mm. The ultrafine crushed product is conveyed to the powder silo for temporary storage; the crushed product is directly conveyed to the powder silo for storage, and then conveyed to the rod mill via a feeder and belt conveyor for further processing; After ultrafine crushing by the two-stage high-pressure roller mill, the particle size distribution of the product is shown in the table below: (5) The product stored in the powder silo in step (4) is transported to a wet screening machine for screening. The oversize product is returned to the second-stage high-pressure roller mill, forming a closed-loop cycle of the second-stage high-pressure roller mill. The undersize product is the ore that has been pre-liberated and separated. The P content in this product is... 80 ≤2mm; (6) The undersize product from step (5) is diluted with water and then transported to the ball mill pump pool. The slurry is then pumped through a pipeline to the hydrocyclone for inspection and classification. The hydrocyclone pressure is controlled at 0.085 MPa. The overflow product flows by gravity through a pipeline to the separation operation. The sand product is returned to the ball mill through a pipeline. The ball mill media filling rate is 32%, and the grinding concentration is 68% of the ore mass. The ball mill discharge product is diluted with water and then enters the ball mill pump pool. The ore mass is pumped through a pipeline by a slurry pump to the inspection and classification hydrocyclone, forming a closed-circuit grinding process in the ball mill.

[0020] As can be seen from the process operation results of the embodiment of the present invention, the total energy consumption of the crushing and grinding system is 18.5 kW·h / t, which is 13.2% lower than that of the traditional SABC process; the nickel recovery rate of the separation operation is increased by 3.5 percentage points and the copper recovery rate is increased by 2.8 percentage points, which verifies the advanced nature and practicality of the process.

Claims

1. A high-pressure roller mill grinding process for unevenly distributed nickel-copper ore, characterized in that, Includes the following steps: (1) Coarse crushing: The nickel-copper ore is coarsely crushed by a standard cone crusher, and the discharge opening is controlled to be 55-52mm; (2) Medium crushing: The coarse crushed product from step (1) is subjected to medium crushing using a short-head cone crusher, with the discharge opening controlled at 25-20mm; (3) Fine crushing: The medium crushed product from step (2) is finely crushed through a high-pressure roller mill, and the roller gap is controlled to be 22-20mm; (4) Ultrafine crushing: The fine crushed product from step (3) is ultrafine crushed through a two-stage high-pressure roller mill, with the roller gap controlled at 16-12mm. The ultrafine crushed product is then transported to the powder silo for temporary storage. (5) Wet screening closed-loop circulation: The ultrafine crushed products in the powder ore bin are screened by a wet screening machine. The products on the screen are returned to the second high-pressure roller mill to form a closed loop circulation. The P80 of the products under the screen is ≤2mm. (6) Closed-circuit ball milling: The undersize product from step (5) is mixed with water and then transported to the ball mill pump pool. The slurry is pumped into the hydrocyclone for inspection and classification. The overflow from the hydrocyclone is used as feed for the separation operation, and the sand is returned to the ball mill to form a closed-circuit grinding.

2. The process according to claim 1, characterized in that, The nickel-copper ore has a nickel grade of 0.55%, a copper grade of 0.30%, and a magnesium oxide content of 28.75%. The main target minerals are nickel sulfide minerals and copper sulfide minerals, and the total content of non-metallic minerals such as serpentine, chlorite, and talc is ≥40%.

3. The process according to claim 1, characterized in that, In step (5), the screen aperture of the wet screening machine is controlled at 4mm×10mm.

4. The process according to claim 1, characterized in that, In step (6), the operating pressure of the hydrocyclone is 0.08-0.10 MPa, the media filling rate of the ball mill is 30-35%, and the grinding concentration is 65-70% of the ore mass.

5. The process according to claim 1, characterized in that, In step (4): the particle size distribution of the product after the two-stage high-pressure roller mill ultrafine crushing meets the following requirement: -200 mesh particle size accounts for ≥40%.

Images