A fine particle grade concentrate slurry dewatering method with high dewatering efficiency

Abstract

This invention discloses a method for dewatering fine-grained concentrate slurry with high dewatering efficiency, comprising the following steps: A) mixing fine-grained concentrate slurry with a flocculant until homogeneous; B) sending the flocculated concentrate slurry into a thickening tank for thickening treatment; C) discharging the high-concentration slurry into a filter for dewatering; D) the overflow water from the thickening tank enters a sedimentation tank for treatment to obtain precipitated overflow water and precipitated concentrate; wherein, by weight, the flocculant comprises the following components: 15-25 parts polyaluminum chloride, 15-25 parts lime, 5-15 parts starch, and 5-10 parts activated carbon. This invention first uses a designed flocculant to flocculate fine-grained concentrate into large-particle concentrate, solving the problems of poor flocculation and sedimentation effect and slow flocculation and sedimentation speed of existing flocculants. Then, through a designed defoaming device and closed-loop circulation process, the yield of fine-grained concentrate is further improved, overcoming the shortcomings of existing dewatering processes.

Description

Technical Field

[0001] This invention relates to the field of slurry dewatering technology, and in particular to a method for dewatering fine-grained concentrate slurry with high dewatering efficiency. Background Technology

[0002] In mineral processing, to extract useful components from ore, large pieces of ore are typically crushed and ground to separate the useful components from gangue minerals, while simultaneously achieving the required particle size for mineral processing. This qualified particle size is then stirred with water and reagents to achieve a suitable concentration for separating the useful minerals. The useful minerals are then separated through processes such as flotation, gravity separation, and magnetic separation, and this concentrate is commonly referred to as concentrate. Because the separation process takes place in water, the resulting concentrate often contains a large amount of water, typically 70%-80%, which does not meet sales requirements.

[0003] Conventional concentrate dewatering processes employ a two-stage process: concentration followed by filtration. Concentrators are used for concentration, while ceramic or disc filters are employed for filtration. Depending on the ore properties and concentrate particle size, the moisture content of the dewatered concentrate typically ranges from 8% to 20%. Concentrate moisture is most significantly affected by particle size. Coarser particles generally result in lower moisture content and better filtration; conversely, finer particles tend to have higher moisture content and lower filtration efficiency. Higher moisture content increases transportation and subsequent smelting costs. More importantly, when concentrate particles are excessively fine (e.g., less than 0.037 mm), they do not settle easily during the concentration and dewatering process. The fine particles tend to clump together at the top of the thickener, causing turbidity and significant concentrate loss. Therefore, the dewatering of fine-particle materials is a recognized technical challenge in the mining and beneficiation industry.

[0004] Currently, some researchers have conducted studies and applied for patents, such as "A dewatering process for fine-grained copper-nickel ore concentrate slurry" (patent application number CN201910459507.6). This technology only addresses the issue of high concentrate moisture content by increasing the number of concentration operations and filtering the concentrate after classification. However, it still suffers from problems such as complex equipment configuration, high investment, high energy consumption, and the inability to handle fine particle turbidity. Furthermore, the presence of fine particles has a serious negative impact on filtration. When using a ceramic filter, fine particles enter the capillary pores of the ceramic plate, clogging it and leading to poor filtration or even damage. When using a disc filter, fine particles penetrate the filter cloth, causing turbidity during filtration and resulting in significant concentrate loss. Summary of the Invention

[0005] The purpose of this invention is to provide a method for dewatering fine-grained concentrate slurry with high dewatering efficiency, addressing the aforementioned problems. This invention employs a dewatering process involving one-time concentration, one-time concentration overflow sedimentation, and one-time filtration. First, a designed flocculant is used to flocculate and agglomerate the fine-grained concentrate into large particles, solving the problems of poor flocculation and sedimentation effect and slow flocculation and sedimentation speed of existing flocculants. Then, a designed defoaming device and closed-loop circulation dewatering process are used to further improve the yield of fine-grained concentrate and overcome the shortcomings of existing dewatering processes.

[0006] The technical solution adopted in this invention is as follows: A method for dewatering fine-grained concentrate slurry with high dewatering efficiency, comprising the following steps:

[0007] A. Feed the fine-grained concentrate slurry into the concentrate flocculation tank, then add the flocculant and stir to mix evenly so that the fine-grained concentrate can be agglomerated into large-grained concentrate after flocculation.

[0008] B. The flocculated concentrate slurry is sent to a thickening tank for thickening treatment.

[0009] C. When the slurry concentration in the thickening zone of the thickener reaches the filtration requirements, the high-concentration slurry is discharged into the filter for dewatering.

[0010] D. The overflow water in the thickening tank enters the sedimentation tank, and after treatment in the sedimentation tank, precipitated overflow water and precipitated concentrate are obtained.

[0011] The flocculant comprises, by weight, the following components: 15-25 parts polyaluminum chloride, 15-25 parts lime, 5-15 parts starch, and 5-10 parts activated carbon.

[0012] In the flocculant of this invention, polyaluminum chloride serves as the primary flocculant carrier. It dissociates into a large number of aluminum ions in water, which can directionally adsorb negatively charged mineral concentrates, achieving efficient flocculation. Starch readily absorbs water, making its molecular chains more loose and forming a starch gel, which assists polyaluminum chloride in enhancing the efficient flocculation of mineral concentrates. Activated carbon, due to its well-developed pore structure, large specific surface area, and abundant surface chemical groups, has a strong specific adsorption capacity. It can de-adsorb chemicals from the surface of mineral concentrate crystals, thereby causing foaming agents, collectors, and other agents to desorb from the surface of the mineral concentrate crystals, exposing clean mineral concentrate crystals that lose their buoyancy, significantly reducing the amount of fine-grained minerals floating and inhibiting turbidity. Lime, through hydrolysis in water, releases OH- ions... -Ions react chemically with the mineral surface (including fine-grained mineral crystals after de-drug treatment), and are directionally adsorbed on the mineral surface to form a hydrophilic film, making the refined minerals hydrophilic and negatively charged minerals. This can work synergistically with activated carbon to inhibit the flotation of fine-grained minerals, while simultaneously promoting better adsorption of these minerals by aluminum ions, thus improving the flocculation effect of polyaluminum chloride.

[0013] Furthermore, when using the flocculant, it is prepared with water into a solution with a mass concentration of 0.5-3%, for example, 0.5%, 1%, 1.5%, 2%, 3%, etc., preferably 1%.

[0014] Furthermore, the mass ratio of the flocculant to the slurry is 2-6:100000, and the concentration of the slurry is 15-30%.

[0015] Furthermore, the thickening tank is equipped with a defoaming device, which includes a high-pressure submersible pump located in the thickening tank. The output of the high-pressure submersible pump is connected to a high-pressure flushing pipe. Multiple high-pressure nozzles are evenly distributed at the output end of the high-pressure flushing pipe. The high-pressure nozzles impact the condensed foam on the liquid surface of the thickening tank, causing the foam to circulate and settle in the thickening tank.

[0016] Furthermore, the spacing between the high-pressure nozzles is 5-15cm.

[0017] Furthermore, the precipitated concentrate discharged from the sedimentation tank is returned to the concentrate flocculation tank for further processing.

[0018] Furthermore, the high-concentration slurry is dewatered in a filter to obtain filter cake and filtrate. The filtrate is returned to the concentrate flocculation tank for further processing.

[0019] Preferably, the flocculant comprises the following components by weight: 20 parts polyaluminum chloride, 20 parts lime, 15 parts starch, and 10 parts activated carbon.

[0020] Furthermore, the sediment overflow water discharged from the sedimentation tank is recycled as production water.

[0021] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0022] 1. This invention adopts a closed-loop process of primary concentration + primary precipitation + filtration + return of precipitated concentrate and filtrate, which greatly improves the filtration efficiency of fine concentrate, effectively solves the problem of concentrate turbidity in traditional processes, and reduces the loss rate of concentrate in overflow water and filtrate by more than 95%.

[0023] 2. This invention uses a high-efficiency flocculant to agglomerate fine concentrate into coarse particles, which can significantly improve the concentration efficiency and create favorable conditions for filtration. It also greatly reduces the probability of fine concentrate entering the filter plate and can effectively extend the service life of the filter plate or filter cloth. Compared with the traditional process, the moisture content of the concentrate can be reduced from 20% to about 7%.

[0024] 3. Adding a sedimentation tank to the overflow water of the thickener can minimize the loss of concentrate. The concentrate overflow water can be directly used for production recycling, which has a beneficial effect on clean production and environmental protection.

[0025] 4. The sedimentation tank recovers the concentrate and filtrate, which are then returned to the flocculation tank. This solves the problem of concentrate loss during the concentration and filtration stages. At the same time, the flocculation process prevents fine particles from forming a vicious cycle throughout the entire process. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a defoaming device according to the present invention;

[0027] Figure 2 This is a flow chart of a method for dewatering fine-grained concentrate slurry with high dewatering efficiency according to the present invention. In the figure, the markings are: 1 for a high-pressure submersible pump, 2 for a high-pressure flushing pipe, 3 for a high-pressure nozzle, 4 for a concentrate flocculation tank, and 5 for a thickening tank. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings.

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] like Figure 1 As shown, a defoaming device for impacting fine foam particles includes a high-pressure submersible pump 1 located within a thickening tank 5. The output end of a concentrate flocculation tank 4 is connected to the input end of the thickening tank 5, and the overflow port of the thickening tank 5 is connected to a sedimentation tank. The high-pressure submersible pump 1 is positioned below the liquid surface and can be fixedly connected to a support of the thickening tank 5. The output of the high-pressure submersible pump 1 is connected to a high-pressure flushing pipe 2, which is located above the liquid surface. Multiple high-pressure nozzles 3 are evenly distributed at the output end of the high-pressure flushing pipe 2. The high-pressure nozzles 3 impact the liquid surface to disperse the fine foam particles that have agglomerated on the liquid surface. Further, the high-pressure nozzles can be spaced 5-15 cm apart, preferably 10 cm.

[0031] like Figure 2 As shown, a method for dewatering fine-grained concentrate slurry with high dewatering efficiency includes the following steps:

[0032] S1. Feed the fine-grained concentrate slurry into the concentrate flocculation tank, then add a high-efficiency flocculant and stir to mix evenly so that the fine-grained concentrate can be agglomerated into large-particle concentrate after flocculation.

[0033] S2. The flocculated concentrate slurry flows by gravity to the central slurry distribution plate of the thickener, and then enters the settling zone of the thickener. The mineral particles are affected by gravity and gather towards the bottom of the thickener to form a high-concentration thickening zone. Some particles that are not flocculated float to the surface to form a fine-grained concentrate foam layer.

[0034] S3. The supernatant in the concentration zone is pumped into the high-pressure flushing pipe by a high-pressure submersible pump. The high-pressure nozzle on the high-pressure flushing pipe impacts the fine foam that has formed on the plate above the concentration tank, causing the fine foam to disperse and freely settle back into the concentration zone of the concentration tank, thereby preventing the fine concentrate from being lost with the overflow water.

[0035] S4. When the slurry concentration in the thickening zone of the thickening tank reaches the filtration requirements (e.g., slurry concentration greater than 50%), the slurry valve located at the bottom of the thickening tank is opened to discharge the slurry into the filter for dewatering. Because most of the fine particles are agglomerated by the flocculant, the fine particles in the slurry agglomerate into coarse particles, and the content of fine particles is relatively reduced, thus reducing the amount of solids entering the ceramic plate or disc filter cloth of the filter. Therefore, the moisture content of the filtered filter cake is also lower, and at the same time, it solves a series of problems such as ceramic plate clogging and disc filter turbidity.

[0036] S5. The overflow water in the thickening tank enters the sedimentation tank. After treatment in the sedimentation tank, the overflow water can be directly used for production water recycling. In order to further solve the problem of turbidity of concentrate filtrate in the filtration process, the concentrate filtrate and the precipitated concentrate at the bottom of the sedimentation tank are combined and pumped to the concentrate flocculation tank for treatment, forming a closed-loop filtration operation. This solves the loss of concentrate in the thickening and filtration process, and also solves the vicious cycle of fine particles in the whole process.

[0037] Furthermore, in this invention, the high-efficiency flocculant is a self-developed flocculant, comprising the following components by weight: 15-25 parts polyaluminum chloride, 15-25 parts lime, 5-15 parts starch, and 5-10 parts activated carbon. The starch particle size is 15-74 μm, preferably 20-50 μm, and the activated carbon particle size is 35-74 μm, preferably 40-70 μm. The flocculant is prepared by weighing each component according to the specified ratio and then mixing them evenly in a mixing device to obtain a solid composite flocculant. In use, the flocculant is prepared with water to a concentration of 0.5-3% by mass, and then added to a concentrate flocculation tank and mixed. The mass ratio of flocculant to slurry is 2-6:100000, and the slurry concentration is 15-30%.

[0038] To better implement this invention, the above-mentioned dewatering method was used for copper concentrate slurry with a slurry concentration of 15%, and Table 1 shows the formulations of some flocculants.

[0039] Table 1. Partial Formulations of Flocculants (Unit: Parts)

[0040]

[0041]

[0042] Examples 1-3 were selected as experimental results for verification, and comparative examples 1-6 were set up. The experimental results are shown in Table 2.

[0043] Table 2. Validation of flocculation effect in Examples 1-3 and Comparative Examples 1-6 (Unit: portions)

[0044]

[0045] Note 1: The total amount of flocculant used to the mass ratio of the test concentrate slurry is 4:100000;

[0046] 2. The concentration and sedimentation time is the time from when the slurry is fed into the concentration tank until more than one-third of the tank changes from turbid to clear.

[0047] As shown in Table 2, the combination of polyaluminum chloride, lime, starch and activated carbon in this invention significantly reduces the concentration and sedimentation time and the solid content in the overflow water. This demonstrates that the composite flocculant of this invention has advantages such as fast sedimentation speed, high dehydration rate and low solid content in the clarified liquid, and the concentrate loss rate is reduced to below 0.06%, overcoming the shortcomings of traditional flocculants.

[0048] Furthermore, to verify the effectiveness of the defoaming device of the present invention, a comparative example 7 was set up. Comparative example 7 was the same as example 1, except that the defoaming device of the present invention was not used. The test results showed that the concentrate content in the overflow water was 0.10%. This demonstrates that the presence of the defoaming device can significantly improve the concentration and sedimentation effect and reduce the loss of fine-grained concentrate.

[0049] Furthermore, to verify the treatment effect of combining the concentrate filtrate and precipitated concentrate and pumping it into the concentrate flocculation tank, a comparative example 8 was set up. Comparative example 8 was the same as example 1, except that the combined slurry was fed into a thickening tank instead of the concentrate flocculation tank. The experimental results were: flocculation settling time was 22 min, and the concentrate content in the overflow water was 0.04%. This shows that directly pumping to the thickening tank affects the yield of fine-grained concentrate, and it is foreseeable that with the increase of the number of cycles, the concentrate content in the overflow water will gradually increase, leading to greater losses of fine-grained concentrate and creating a vicious cycle.

[0050] 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 protection scope of the present invention.

Claims

1. A method for dewatering fine-grained concentrate slurry with high dewatering efficiency, characterized in that, Includes the following steps: A. Feed the fine-grained concentrate slurry into the concentrate flocculation tank, then add the flocculant and stir to mix evenly so that the fine-grained concentrate can be agglomerated into large-grained concentrate after flocculation. B. The flocculated concentrate slurry is sent to a thickening tank for thickening treatment. C. When the slurry concentration in the thickening zone of the thickening tank reaches the filtration requirements, the high-concentration slurry is discharged into the filter for dewatering. After dewatering in the filter, the high-concentration slurry yields filter cake and filtrate. The filtrate is returned to the concentrate flocculation tank for further processing. D. The overflow water in the thickening tank enters the sedimentation tank, and after treatment in the sedimentation tank, precipitated overflow water and precipitated concentrate are obtained; the precipitated concentrate is returned to the concentrate flocculation tank for further processing. The flocculant comprises, by weight, the following components: 15-25 parts polyaluminum chloride, 15-25 parts lime, 5-15 parts starch, and 5-10 parts activated carbon.

2. The method for dewatering fine-grained concentrate slurry with high dewatering efficiency as described in claim 1, characterized in that, When using the flocculant, it is prepared into a solution with a mass concentration of 0.5-3% using water.

3. The method for dewatering fine-grained concentrate slurry with high dewatering efficiency as described in claim 2, characterized in that, The mass ratio of the flocculant to the slurry is 2-6:100000, and the concentration of the slurry is 15-30%.

4. The method for dewatering fine-grained concentrate slurry with high dewatering efficiency as described in claim 1, characterized in that, The thickening tank is equipped with a defoaming device, which includes a high-pressure submersible pump located inside the thickening tank. The output end of the high-pressure submersible pump is connected to a high-pressure flushing pipe, which is fixed on the frame of the thickener. Multiple high-pressure nozzles are evenly distributed at the output end of the high-pressure flushing pipe, which impact the liquid surface of the thickening tank.

5. The method for dewatering fine-grained concentrate slurry with high dewatering efficiency as described in claim 4, characterized in that, The spacing between the high-pressure nozzles is 5-15cm.

6. The method for dewatering fine-grained concentrate slurry with high dewatering efficiency as described in claim 5, characterized in that, The flocculant comprises the following components by weight: 20 parts polyaluminum chloride, 20 parts lime, 15 parts starch, and 10 parts activated carbon.

7. The method for dewatering fine-grained concentrate slurry with high dewatering efficiency as described in claim 6, characterized in that, The sediment overflow water discharged from the sedimentation tank is used for production water recycling.

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