CN114212911A

CN114212911A - Tailing separation method

Info

Publication number: CN114212911A
Application number: CN202111448507.XA
Authority: CN
Inventors: 欧阳仕元; 田志刚; 杜向红; 方振鹏; 崔国伟; 汤德益; 张幼权; 刘运财
Original assignee: Fankou Lead Zinc Mine of Shenzhen Zhongjin Lingnan Nonfemet Co Ltd
Current assignee: Fankou Lead Zinc Mine of Shenzhen Zhongjin Lingnan Nonfemet Co Ltd
Priority date: 2021-11-30
Filing date: 2021-11-30
Publication date: 2022-03-22
Anticipated expiration: 2041-11-30
Also published as: CN114212911B

Abstract

The application relates to the technical field of tailing treatment, and provides a tailing slurry thickening method, which comprises the following steps: carrying out first thickening treatment on the tail mortar to obtain a first underflow and a first overflow; performing hydraulic cyclone treatment on the bottom flow to obtain settled sand and a second overflow; filtering the settled sand to obtain a filtrate and a filter cake; mixing the first overflow, the second overflow and the filtrate to obtain a mixed solution; and adding a flocculant solution into the mixed solution, and then carrying out second thickening treatment to obtain a third overflow and a second underflow. The tailing separation method provided by the application can be used for carrying out thickening treatment on ore pulp, and the obtained first underflow and filter cake can be used as filling materials, so that a way for improving utilization of tailing is provided.

Description

Tailing separation method

Technical Field

The application belongs to the technical field of tailings, and particularly relates to a tailing separation method.

Background

The tailings are used as main waste discharged by solid waste of mines, and account for large proportion of discharged industrial solid waste. The main current modes of tailings disposal and utilization are tailings pond drainage and downhole filling.

When the tailing pond is discharged, low-concentration tailing slurry generated by a common selection plant is directly discharged to the tailing pond through a pipeline or is discharged to the tailing pond after being thickened by a thickener, the tailing slurry naturally settles and dehydrates in the tailing pond, and backwater is conveyed to the selection plant for continuous use.

And (3) by utilizing tailing filling, thickening the tailing slurry to a higher concentration, adding cementing materials such as cement and the like, stirring or directly conveying the mixture to the underground goaf. The concentration of the tailing slurry reaches a paste state or approaches to the paste state after the tailing filling is required to be dense, so that the prepared filling slurry cement is prevented from being isolated, and the underground dewatering amount is small. Meanwhile, the tailing filling is required to be utilized in full grade as much as possible, so that the problems that the fine grade is discharged to a tailing pond and cannot be dammed, and the dehydration is difficult in the tailing pond, which causes great potential safety hazards, are avoided. Therefore, the full tailings slurry paste thickening technology is the core technology of tailing paste discharge and full tailings paste filling.

At present, the total tailing slurry paste concentration method mainly comprises 3 methods:

the first is to convey the tailings slurry of the selection plant to a common thickener for thickening, the underflow concentration of the thickener generally reaches about 40 percent, then the tailings slurry is conveyed to a sand silo for sedimentation, dehydration and thickening again to a higher concentration, the overflow of the sand silo contains part of fine fraction, and the tailings slurry can be used after further treatment;

and the second method is to convey the tailings slurry of the selecting plant to a deep cone thickener, and the underflow concentration of the deep cone thickener is greatly improved by adding a flocculating agent and adopting technical measures such as a large height-diameter ratio, a stirring rod, a pressure-resistant rake and the like.

And the third is to carry out ceramic filtration or filter pressing dehydration treatment on the tailing slurry discharged from a plant selection or the tailing slurry thickened by a common thickener, wherein the dehydrated full tailing slurry has low water content and can be directly conveyed to a tailing pond or a dry storage yard by a belt or a vehicle for discharging, and when the full tailing slurry is used for filling, water is generally added to adjust the slurry concentration to have certain pipeline conveying capacity. The wastewater dehydrated by ceramic filtration or filter pressing can be utilized only after being further treated.

The first and second methods mainly use the sedimentation dehydration principle, and the difference is that the first method uses a common thickener and a sand silo to carry out sedimentation dehydration twice, overflow can be used after treatment, the second method uses a flocculating agent to accelerate sedimentation,

the paste concentration is realized by the technology that the bin body with large height-diameter ratio is utilized, the stirring rod destroys the water-sand combination state of the slurry at the bottom, and the rake-preventing measure prompts the high-concentration settled layer of the sand bin to smoothly discharge the slurry. The first and second methods have unstable effect on the thickening of the whole tailings paste and are greatly influenced by the property difference of the tailings, and if the average diameter of the tailings is finer, the thickening concentration of the first and second methods cannot reach the paste property, the thickening concentration is lower, and the overflow concentration of the first method is higher. When the method is used for underground filling, the second method has no stock bin for storing the tailing paste, and is influenced by the operation time of selecting factories. The third method adopts mechanical sand aligning

The slurry is subjected to solid-liquid separation, but the separated wastewater still needs to be treated for utilization, so that the dehydration efficiency is low, the energy consumption is high, the process is complicated, and the cost is high. The third method has poor applicability to the properties of tailings, and ceramic filter pores are easily blocked and cannot be used smoothly if the sulfur content in the full-tailings slurry is high or the average particle size of the tailings is fine. The prior tailing thickening technology generally utilizes the principles of natural sedimentation dehydration, centrifugal sedimentation dehydration, mechanical dehydration and the like, and the principles have poor effect on the full tailing slurry with large mud content. The centrifugal sedimentation principle and the vibration dehydration principle of the cyclone are matched with the thickening principle, so that the thickening efficiency is high, the effect is good, and the cyclone thickening agent is only suitable for tailings with lower mud content.

Disclosure of Invention

The application aims to provide a tailing slurry thickening method, and aims to solve the technical problems of fine tailing slurry, low sedimentation rate, low underflow concentration and high overflow turbidity in the prior art.

In order to achieve the purpose of the application, the technical scheme adopted by the application is as follows:

the application provides a tail mortar thickening method, which comprises the following steps:

carrying out first thickening treatment on the tail mortar to obtain a first underflow and a first overflow;

performing hydraulic cyclone treatment on the bottom flow to obtain settled sand and a second overflow;

filtering the settled sand to obtain a filtrate and a filter cake;

mixing the first overflow, the second overflow and the filtrate to obtain a mixed solution;

and adding a flocculant solution into the mixed solution, and then carrying out second thickening treatment to obtain a third overflow and a second underflow.

The tailing separation method provided by the application can be used for carrying out thickening treatment on ore pulp, the obtained first underflow and filter cakes can be used as filling materials and is a way for improving utilization of tailing, wherein the tailing pulp is subjected to the first thickening treatment, the tailing pulp can be subjected to preliminary treatment to obtain first underflow with improved concentration and first overflow with reduced concentration, the first underflow can be subjected to hydraulic cyclone and filtration treatment to further separate water from the first underflow to obtain filter cakes, and in addition, the first overflow, the second overflow, filtrate and a flocculant solution are mixed to carry out second thickening treatment, so that turbidity of a mixed solution can be reduced, and dispersity of the tailing in the mixed solution can be reduced.

Drawings

FIG. 1 is a flow chart of a mixed tailings densification process provided in an embodiment of the present invention;

FIG. 2 is a plot of sedimentation height for full tailings under three ionic flocculants in accordance with an embodiment of the present invention;

FIG. 3 is a plot of settling rate for three flocculants for whole tailings provided in an example of the present invention;

FIG. 4 is a plot of settling height for full tailings at various feed concentrations as provided in an example of the present invention;

FIG. 5 is a graph of settling velocity for full tailings at various feed concentrations provided in an example of the present invention;

FIG. 6 is a graph of the total tailings solids throughput per unit area for different feed concentrations provided in an embodiment of the present invention;

FIG. 7 is a plot of the sedimentation height of the whole tailings provided in an embodiment of the present invention;

FIG. 8 is a plot of the settling velocity of the whole tailings provided in an embodiment of the present invention;

FIG. 9 is the average settling velocity within 2min for different flocculants for whole tailings provided in the example of the present invention;

FIG. 10 is a graph of the optimum set of settling heights for three tailings slurries provided in an example of the present invention;

FIG. 11 is a graph of the optimum set settling velocity for three tailings slurries provided in an example of the present invention;

FIG. 12 is a graph of fine grit tailings overflow water turbidity as a function of time as provided in an embodiment of the present invention;

FIG. 13 is a graph of fine grit tailings overflow water turbidity as a function of time as provided in an embodiment of the present invention;

FIG. 14 is a time-varying digital dot plot of the height of a fine tailings mud layer provided in an embodiment of the present invention;

FIG. 15 is a time-dependent variation law of the height of the fine tailings cone section mud layer provided in the embodiment of the present invention;

FIG. 16 is a variation law of the height of the mud layer of the straight section of fine tailings provided in the embodiment of the present invention;

fig. 17 is a straight-barrel section mud layer height linear regression model with different cone angles provided in the embodiment of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application more clearly apparent, the present application is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

In this application, the term "and/or" describes an association relationship of associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a is present alone, A and B are present simultaneously, and B is present alone. Wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.

In the present application, "at least one" means one or more, "a plurality" means two or more. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, "at least one (a), b, or c", or "at least one (a), b, and c", may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, and c may be single or plural, respectively.

It should be understood that, in various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the execution sequence, some or all of the steps may be executed in parallel or executed sequentially, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the examples of this application and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

The weight of the related components mentioned in the description of the embodiments of the present application may not only refer to the specific content of each component, but also represent the proportional relationship of the weight among the components, and therefore, the content of the related components is scaled up or down within the scope disclosed in the description of the embodiments of the present application as long as it is scaled up or down according to the description of the embodiments of the present application. Specifically, the mass described in the specification of the embodiments of the present application may be a mass unit known in the chemical industry field such as μ g, mg, g, kg, etc.

The terms "first" and "second" are used for descriptive purposes only and are used for distinguishing purposes such as substances from one another, and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. For example, a first XX may also be referred to as a second XX, and similarly, a second XX may also be referred to as a first XX, without departing from the scope of embodiments of the present application. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

The embodiment of the application provides a tail mortar thickening method, which comprises the following steps:

step S1, carrying out first thickening treatment on the tail mortar to obtain a first underflow and a first overflow;

step S2, performing hydraulic cyclone treatment on the underflow to obtain settled sand and a second overflow;

step S3, filtering the settled sand to obtain filtrate and a filter cake;

step S4, mixing the first overflow, the second overflow and the filtrate to obtain a mixed solution;

and step S5, after adding a flocculant solution into the mixed solution, performing second thickening treatment to obtain a third overflow and a second underflow.

The tailings separation method provided by the embodiment of the application can perform thickening treatment on ore pulp, and the obtained first underflow and filter cake can be used as filling materials, so that the utilization of tailings is improved.

In step S1, the tail mortar is subjected to a first thickening treatment to obtain a first underflow and a first overflow.

In some embodiments, the tailings that form the tailings slurry comprise at least one of a full tailings, a fine fraction tailings, and a graded tailings.

Wherein, the particle size distribution of the full tailings is generally that the mass of the full tailings is 100%, and the mass percentage of the full tailings with the particle size of less than 19 μm is more than 55%.

The mass of the fine fraction tailings with the particle size of less than 19 mu m accounts for more than 55 percent based on 100 percent of the mass of the fine fraction tailings.

The mass proportion of the grading tailings with the particle size of less than 19 mu m is 6.50 percent based on 100 percent of the mass of the grading tailings.

The grading tailings are generally distributed in such a way that the particle size of less than 19um only occupies 6.50%, and the grade of-19 um of more than 15% is required at minimum according to the requirements of paste preparation on the particle size, so that the flow characteristic can be displayed, enough water in a colloidal state is kept, and a non-segregation mixture is formed. The grain size composition of the four tailings, namely the full tailings, the fine-fraction tailings and the mixed tailings meets the paste preparation conditions, the grain size of the graded tailings of-19 mu m only accounts for 6.50 percent and is far less than 15 percent, and the graded tailings cannot be prepared into the paste.

In some embodiments, the weight ratio of the tailings forming the tail mortar, that is, the weight concentration of the tail mortar is 4-16%, wherein the weight ratio of the tailings of the tail mortar can be 4%, 8%, 12% and 16%, and as the slurry concentration increases, the slurry flocculation settling speed gradually decreases, but the decrease amplitude decreases, and the solid treatment capacity per unit area increases first and then decreases.

The ore full tailings have the fastest sedimentation speed at 4 percent concentration, but have small solid treatment capacity; the maximum solids throughput was reached at 12% concentration. The common deep cone thickener self-dilution system can dilute one time, and the required dilution multiple is larger, and the large dilution multiple has certain difficulty in the existing thickener technology. Comprehensively considering the tailing solid treatment capacity, the tailing feeding concentration and the technical feasibility of self-dilution of a thickener, 12 percent is recommended to be selected as the concentration of the whole tailing after dilution.

In some embodiments, the solids flux of the tailings slurry is 0.2-0.5 t/m²H, wherein the solids flux of the tail mortar may be 0.2t/m².h、0.3t/m².h、0.4t/m².h、0.5t/m²H, underflow concentration decreases with increasing solids flux.

In some embodiments, the underflow is subjected to hydrocyclone treatment using a hydrocyclone in step S2 to obtain the sand setting and the second overflow.

In some embodiments, the underflow is filtered using a ceramic filter in step S3 to obtain a settled sand with a concentration of 70% by mass of tailings.

In some embodiments, the first overflow, the second overflow, and the filtrate in the transport way reservoir are mixed using a pipe and a pump in step S4.

In step S5, after a flocculant solution is added to the mixed liquor, a second thickening treatment is performed to obtain a third overflow and a second underflow, which can improve the overall recovery rate of the tailings.

In some embodiments, the flocculant forming the flocculant solution comprises an anionic or nonionic polyacrylamide.

Furthermore, the weight average molecular weight of the anionic polyacrylamide is 1000-1400 ten thousand, and the maximum settling speed of the full-tailing slurry added with the anionic flocculant is gradually increased along with the continuous increase of the weight average molecular weight.

Furthermore, the weight average molecular weight of the nonionic polyacrylamide is 800-1600 ten thousand, and the maximum sedimentation speed of the full-tailing slurry added with the nonionic flocculant is gradually increased along with the continuous increase of the weight average molecular weight.

In some embodiments, the flocculant is added into the mixed liquor according to a proportion of 10-80 g per ton of tailings, wherein the flocculant is added into the mixed liquor according to a proportion of 10g, 30g, 40g, 50g, 60g, 70g and 80g per ton of tailings, and for the whole tailings, the sedimentation speed is faster and faster along with the increase of unit consumption, but the increase amplitude is smaller. However, when the unit consumption of the flocculating agent is increased from 10g to 30g, the sedimentation speed is rapidly increased, and after the unit consumption of the flocculating agent exceeds 30g, the sedimentation speed is slowly increased. Thus, the optimum flocculant specific consumption for full tailings is 30 g.

Furthermore, the adding flow rate of the flocculant solution is 33.9-148.4 ml/min, and the adding amount of the flocculant is further controlled by controlling the flow rate of a flocculant pump.

In some embodiments, the second concentration step comprises: and treating the mixed solution by adopting a deep cone thickening treatment method.

Further, the deep cone thickening treatment method is implemented by a deep cone thickener, and the setting conditions of the deep cone thickener are as follows:

the cone angle of the deep cone thickener is 30-60 degrees, wherein the cone angle of the deep cone thickener can be 30 degrees, 45 degrees and 60 degrees, the mud layer of the cone angle section with the larger cone angle rises faster, and when the rising speed of the mud layer is higher (when the cone angle is larger), the stored material of the thickener is less under the conditions of equal height. In other words, if the cone angle is larger for a given stock of thickener, the height required is larger.

Furthermore, the diameter of the deep cone thickener is 16-30 m, the recommended diameter of the deep cone thickener is 18m, and the deep cone thickener is compatible with various continuous tailing thickening working conditions. Three tailing thickening technical processes and parameters are designed, and a fine-fraction tailing thickening technical process is finally recommended, so that the tailing thickening technical process is conveniently and smoothly connected with the existing filling technology.

According to the actual production current situation and future production planning of the Van-Kou lead-zinc ore, the diameter of a full-tailing design thickener is determined to be 18m, the cone angle is 30 degrees, and the height of the thickener is 20 m; the diameter of the fine-grain tailings is designed to be 17m, the cone angle is 30 degrees, and the total height of the thickener is 17 m; the diameter of the thickener designed for mixed tailings is 16m, the cone angle is 30 degrees, and the thickening height is 20 m. In order to meet the field production requirement, the diameter of the deep cone thickener is finally determined to be 18m, the cone angle is 30 degrees, the height of the thickener is 20m, and the thickening operation of full tailings and fine tailings can be considered.

Furthermore, the rotating speed of the rake frame of the deep cone thickener is 1-3 r/min, and the ascending rate of the deep cone thickener is close to that of the deep cone thickener with the same cone angle and different rake frame rotating speeds.

In some embodiments, the pH value of the mixed solution is 8.68-9.96, the average value of the third overflow pH value is 7.73-9.98, and the flocculant is added into the mixed solution to change the pH value of the mixed solution, so that the precipitation of tailings is facilitated.

In some embodiments, the COD value of the mixed solution is 387-23402 mg/L, the COD value of the third overflow is 387-564 mg/L, the pH value is 6-9 according to the sewage discharge requirement of the national standard GB25466-2010, the COD value is below 60mg/L when the mixed solution is directly discharged, and the COD value is lower than 200mg/L when the mixed solution is indirectly discharged, so that the mixed solution can be normally discharged. Therefore, the overflow turbidity of the thickened tailings is within 100ppm, but the COD value obviously exceeds the standard, and the tailings are not allowed to be directly discharged. The overflow water is recommended to be discharged to the original water treatment system by the mine, the water treatment quality is enhanced, and the COD value is reduced to 60mg/L and then discharged to the environment.

In some embodiments, the weight ratio of the tailings contained in the second underflow is 56-62.5%, and the water turbidity of the third overflow is less than 200ppm, which indicates that the separation degree of water and tailings can be improved by using the tailing slurry thickening treatment method of the embodiments of the present application.

In some embodiments, R of the packing element formed by the second underflow_3dThe strength of the composite material is more than 3MPa, and the composite material can meet the requirements of being used as a filling body.

In some embodiments, R of the packing element formed by the second underflow_28dThe strength of the composite material is more than 3MPa, and the composite material can meet the requirements of being used as a filling body.

The following description will be given with reference to specific examples.

Example 1

Fig. 1 provides a flow chart of a tailings separation method, specifically, comprising the steps of:

step S101, firstly, checking experimental equipment and instruments, ensuring that related equipment can normally operate, then performing development work, opening a full-tailing feed gate valve, filling a full-tailing transfer pool near a 24m thickener with full-tailing slurry, and measuring the mass concentration of the full-tailing slurry.

Step S102, measuring the concentration of the full tailings by using a concentration pot, and adjusting the feeding flow of the full tailings according to the optimal solid flux when the concentration of the tailings is lower than the optimal feeding concentration by 12%; when the total tailings concentration is 12% higher than the optimum feed concentration, the slurry is diluted to the optimum feed concentration by back-calculating the dilution water flow.

And S103, adjusting clear water pumps (controlling dilution water flow), slurry pumps (controlling whole tailing feeding flow) and screw pump pumping parameters to design values (controlling flocculant flow) according to the whole tailing feeding parameters and field concentration test results, and ensuring that experiments can be carried out without errors.

Step S104, in this embodiment, the mass concentration of the full tailings slurry is 12%, and a 24m thickener is used to perform a first thickening treatment on the full tailings slurry, so as to obtain a first underflow with a mass concentration of 25% and a first overflow with a mass concentration of 6.56%.

And step S2, performing hydrocyclone treatment on the first underflow to obtain settled sand with the mass concentration of 70% and second overflow with the mass concentration of 9.1%.

And step S3, treating the settled sand by using a ceramic filter to obtain filtrate and a filter cake, and transporting the filter cake to a tailing yard and a filling station.

And step S4, mixing the first overflow, the second overflow and the filtrate to obtain a mixed solution with the mass concentration of 7.13%.

And S501, starting a clear water pump, filling clear water into a deep cone thickener with the depth of 17m, and starting a rake frame, wherein the rotation speed of the rake frame is 6-7 r/min.

And S502, weighing a certain amount of flocculant, preparing the flocculant into 0.01% flocculant solution through a flocculant automatic preparation system of the system, and fully stirring for 40min, so that an experiment can be performed. And the screw pump of the system is utilized, and the flow is detected by utilizing a rotameter.

And S503, pumping the full-tailing slurry into a mixing drum near a 17m deep cone thickener through a sludge pump, and simultaneously starting a mixing system to fully mix the full-tailing slurry so as to ensure that full-tailing particles are not settled.

And S504, in 24 hours after the experiment is started, in order to find the optimal unit consumption of the flocculating agent, the whole tailings are kept unchanged at the solid flux of 0.4t/m2.h, the unit consumption of the flocculating agent is added from 60 to 60, each unit consumption lasts for 8 hours, and the optimal unit consumption of the flocculating agent is determined according to the turbidity value of overflow water.

And S505, when the mud layer reaches 6-8 m, keeping the solid flux unchanged, setting experiment parameters according to the optimal unit consumption of the flocculating agent, starting a first overflow pump, and continuously feeding and discharging for 24 hours.

And S506, ensuring continuous feeding, opening a second underflow pump, and quickly discharging to enable the height of the mud layer to reach 3 m.

And step S507, keeping the feeding unchanged, closing the second underflow pump, and respectively detecting the second underflow concentration when the height of the mud layer is 3, 4, 6 and 8m in the process of rising to 8 m.

And step S508, stopping feeding, allowing the mud layer to stand for 8 hours, and periodically measuring the underflow concentration and detecting the torque of the rake frame.

Step S509, opening the underflow pump, closing the feeding pump, and entering a discharge mode

And step S510, adding a flocculant solution with the mass concentration of 0.01% into the mixed solution, performing second thickening treatment by using a 17m deep cone thickener to obtain a third overflow with the mass concentration of 24.07 and a second underflow with the mass concentration of 55.03, and conveying two drops into a filling station.

According to the actual production condition of the mine site, combining with the fine-fraction tailings thickening parameters and the equipment structure parameters, the processing capacity of the thickener can be calculated (calculating the average fine-fraction tailings output in the tailings section), the dilution water flow can be calculated according to the average feeding concentration and the dilution concentration, and meanwhile, according to the related parameters, the feeding volume of tailings in unit time and the feeding volume of flocculant in unit time can be calculated. See table 1 for details.

The dry sand processed by the deep cone thickener in unit time of 46.07t/h and the underflow yield of 52.72m can be determined by the daily average yield and the underground filling amount of the selected plants³Per hour, overflow water discharge amount 585.7m³The filter cake yield was 42.73 t/h.

Similarly, when a 16m diameter deep cone thickener was used to treat fine tailings, the average solids flux was 0.20t/m²H, less than the recommended solids flux of 0.25t/m²H. The reason is that when the thickener is designed, the fluctuation coefficient of 1.15 is considered in the feeding flow of the fine-grained tailings. If a 18m deep cone thickener is used, the average solid flux drops to 0.18t/m2. h. And the lower solid flux is more favorable for improving the underflow concentration of the fine-fraction tailings and reducing the overflow turbidity of the fine-fraction tailings. Meanwhile, the larger thickener has stronger capacity of storing tailings, and is used for adjusting the contradiction between continuous production of the thickener and discontinuous operation of underground filling.

When a 17 m-diameter deep cone thickener is adopted to treat fine tailings, the average solid flux is 0.29t/m²H, less than the recommended solids flux of 0.35t/m²H. The reason is that when the thickener is designed, the fluctuation coefficient of 1.15 is also considered in the feeding flow of the fine-fraction tailings. When the recommended 18m deep cone thickener is adopted, the average solid flux is further reduced to 0.23t/m²H. The fluctuation of the supply parameters of the mixed tailings is large, the large thickener adapts to the fluctuation degree of the feed flow, and the safety factor of the production of stable mixed tailings is large.

In the process of thickening, overflow generated by a 24m thickener, overflow generated by a hydrocyclone and filtrate generated by a ceramic filter are regulated and controlled to enter a deep cone thickener for thickening, fine-grained tailings, namely graded tailings, entering the thickener are required in the process, the graded tailings are 1:1, the thickening flow chart is shown in fig. 8-5, the thickening parameters are shown in a table 8-3, in the normal production process, overflow water is discharged to a water collecting tank for treatment or discharged or pumped to a concentrating mill for recycling, underflow is conveyed to a filling station to be mixed and stirred with a cementing material according to a certain proportion, and the underflow is conveyed to a well for underground filling after being uniformly stirred. When the deep cone thickener has a fault, the original 30m ordinary thickener in the tailing section can be used as an accident facility.

The daily average production and the underground filling amount of the selected plants are calculated. Can determine the dry sand processing time unit 57.59t/h of the deep cone thickener and the underflow output of 53.31m³Per hour, overflow water discharge amount 597.07m³The cake yield was 31.21 t/h.

Example 2 to example 4

The tailings separation method used in examples 2 to 4 was the same as that used in comparative example 1, except that several nonionic flocculants having different weight average molecular weights were selected, as shown in table 1.

TABLE 1 non-ionic flocculants of different weight average molecular weights

Experiment number	Example 2	Example 3	Example 4
				Type (B)	Is not	Is not	Is not
Weight average molecular weight per ten thousand	800	1200	1400～1600

Comparative example 1

The tailings separation methods used in comparative examples 2 to 1 were the same, except that comparative example 1 did not use a flocculant, and the first overflow was directly subjected to an experiment using a deep cone thickener, and the experimental results are shown in fig. 2 to 3.

And analyzing the sedimentation effect of the full tailings under the condition of different weight average molecular weights, wherein the weight average molecular weight of the nonionic flocculant is 800-1600 ten thousand, and the maximum sedimentation speed of the full tailings slurry added with the nonionic flocculant is gradually increased along with the continuous increase of the weight average molecular weight.

Example 5 to example 7

The concentration of the tailing pulp in the current district factory is about 16%, and generally, the pulp is diluted before entering a deep cone in order to reduce interference among tailings. In order to determine the optimal settling concentration of the tailings, settling experiments with different slurry concentrations were performed. The tailings separation methods used in comparative examples 2 to 1 were the same, except that a flocculant solution having an optimum flocculant preparation concentration of 1/5000 was used and the unit flocculant consumption was set to 30g/t as shown in table 2.

Table 2 dilution concentration protocol table

The sedimentation height data of the whole tailings under different feeding concentrations are shown in an attached table 3, the sedimentation height curve is shown in a graph 4, and the sedimentation velocity curve is shown in a graph 5.

TABLE 3 Total tailings solids treatment gauge for different feed concentrations

Feed concentration/%)	4	8	12	16
					Time per min of interference point	2	3	5	8
Height of interference point/mm	17.5	45.5	65	101
					Concentration of interference points/%)	29.8	30.7	33.4	30.9
Speed of interference point/mm.min ^-1	5	5	6	6
					Solid flux/t.m^-2·h^-1	0.277	0.286	0.373	0.345

As can be seen from fig. 6, as the slurry concentration increases, the slurry flocculation settling rate gradually decreases, but the decrease rate decreases, and the solid treatment capacity per unit area increases first and then decreases.

The ore full tailings have the fastest sedimentation speed at 4 percent concentration, but have small solid treatment capacity; the maximum solids throughput was reached at 12% concentration. The common deep cone thickener self-dilution system can dilute one time, and the required dilution multiple is larger, and the large dilution multiple has certain difficulty in the existing thickener technology.

Examples 8 to 12

Comprehensively considering the tailing solid treatment capacity, the tailing feeding concentration and the technical feasibility of self-dilution of a thickener, 12 percent is recommended to be selected as the concentration of the whole tailing after dilution.

In the preferable process of the unit consumption of the flocculating agent, the concentration of the slurry is 12%, the optimal flocculating agent with the dilution concentration of 1/5000 is used, the unit consumption of the flocculating agent is respectively set to be 10g/t, 30g/t, 50g/t, 70g/t, 90g/t and 110g/t, the slurry is prepared from low to high according to the unit consumption of the flocculating agent, the difference of the liquid level height is kept as small as possible, and the unit consumption of the flocculating agent is preferable. The specific scheme is shown in table 4.

TABLE 4 preferred flocculant consumption protocol

Experiment number	Example 8	Example 1	Example 9	Example 10	Example 11	Example 12
							Unit consumption of flocculant (g/t)	10	30	50	70	90	110
Full tailings quality (g)	60	60	60	60	60	60
							Water quality (g)	437	431	425	419	413	407
Mass (g) of flocculant solution	3	9	15	21	27	33

And observing the sedimentation condition of the tailings. In order to represent the influence of the flocculating agent on the tailing sedimentation speed, the average sedimentation rate under different unit consumption conditions in the first 2min is selected as a measurement index, and the optimal unit consumption of the flocculating agent is determined. The sedimentation height data of the whole tailings are shown in an attached table 4, the sedimentation height curve is shown in a figure 7, and the sedimentation velocity curve is shown in a figure 8. The average settling rate in 2min of the whole tailings is shown in FIG. 9.

As can be seen from fig. 9, the settling rate becomes faster and faster with the increase of unit consumption for the whole tailings, but the increase becomes smaller. However, when the unit consumption of the flocculating agent is increased from 10g/t to 30g/t, the sedimentation speed is rapidly increased, and after the unit consumption of the flocculating agent exceeds 30g/t, the sedimentation speed is slowly increased. Therefore, the optimal flocculant unit consumption of the whole tailings is 30 g/t.

Example 13 to example 15

From the previous flocculant selection, the recommended flocculant is a non-ionic flocculant. Through feed concentration optimization and flocculant unit consumption optimization experiments, the optimal feed concentration of the full tailings is determined to be 12%, and the unit consumption of the flocculant is determined to be 30 g/t; the optimal feeding concentration of the fine-fraction tailings is 8%, and the unit consumption of the flocculating agent is 50 g/t; the optimal feeding concentration of the mixed tailings is 8%, and the optimal unit consumption of the flocculating agent is 30 g/t. The optimal static concentration parameters of the three tailings are compared to determine the optimal type of the tailings suitable for the ore of all mines. The sedimentation height data of the optimal group of the three tailings are shown in an attached table 5, the sedimentation height curve is shown in a figure 10, and the sedimentation velocity curve is shown in a figure 11.

TABLE 5 verification experiment design Table

Serial number	Group of	Slurry concentration/%)	Flocculant Unit consumption/g.t^-1
				Example 13	Full tailings	12	30
Example 14	Fine fraction tailings	8	50
				Example 15	Mixed tailings	8	30

After the turning points on each curve are determined, the corresponding solid treatment amount per unit area is calculated, and the calculation results are shown in table 6.

TABLE 6 solid treatment amount per unit area calculation table

Item	Full tailings	Fine fraction tailings	Mixed tailings
				Time per min of interference point	4.5	3.5	3
Height of interference point/mm	86	89.5	76
				Mass concentration of interference points/%)	29.0	19.7	22.8
Speed of interference point/mm.min ^-1	8	11	10
				Solid flux/t.m^-2·h^-1	0.432	0.384	0.394

As can be seen from fig. 11 and table 6, the unit consumption of the full tailings and the mixed tailings flocculant are the same, but the feeding concentration of the full tailings is greater than that of the mixed tailings, and the solid flux is also greater than that of the full tailings, so that the flocculation and sedimentation effects of the full tailings are better than those of the mixed tailings; the feeding concentration of the mixed tailings is the same as that of the fine-grained tailings, but the unit consumption of a fine-grained tailing flocculant is high, and the solid flux of the fine-grained tailings is also smaller than that of the mixed tailings, so that the fine-grained tailings are inferior to the mixed tailings in terms of the tannin settling effect; finally, the flocculation effects of three tailings are sequenced: full tailings > mixed tailings > fine fraction tailings.

According to the conclusion of the early-stage static thickening experiment, the feed concentration of the diluted full-tailing slurry is determined to be 12%, the unit consumption of the flocculating agent is 30g/t, and the optimal solid flux is 0.432; the feed concentration of the diluted fine-fraction tailing slurry is 8%, the unit consumption of the flocculating agent is 50g/t, and the optimal solid flux is 0.384; the feed concentration of the diluted mixed tailing slurry is 8%, the optimal unit consumption of the flocculating agent is 30g/t, and the optimal solid flux is 0.444.

Examples 16 to 27

In order to optimally select the optimal solid flux and the optimal unit consumption of the flocculating agent, three tailings 2-factor 4 horizontal dynamic thickening experiments are carried out. The experimental contents are shown in table 7.

Table 7 indoor dynamic concentration experiment two-factor four-level uniform experiment design table

In the fine-fraction tailing dynamic thickening experiment, the height of a mud layer is designed to be 65cm, the rotating speed of a rake frame is 3rad/min, and the experiment method is 2-factor-4 level; and respectively determining the optimal solid flux and the optimal flocculant unit consumption. And (3) opening the underflow pump after the mud layer reaches the circulation height in each independent horizontal experiment, performing underflow circulation operation, discharging tailing slurry in the settling column after circulation meets 2-4h, finishing the experiment, and finishing the experimental instrument. The parameters relevant to the experimental setup are shown in tables 8, 9 and 10.

Table 8 fine grit experimental design parameter table

TABLE 9 full tailings experiment design parameter table

TABLE 10 design parameter table for mixed tailings experiment

The results are shown in the attached Table 11. According to the experimental record, the turbidity value of the overflow water of the fine-fraction tailings fluctuates between 30 ppm and 80ppm along with the change of time, the mean value of the turbidity value is 53.9, the turbidity of the overflow water is kept fluctuating within a certain range along with the increase of the time of the experiment in the whole experiment process, and the change curve of the turbidity of the overflow water is shown in fig. 12.

As can be seen from the experimental results shown in table 11, as the experiment time increases during the whole experimental process, the underflow concentration decreases to a certain extent at the early stage, then increases, and remains substantially constant at the later stage, and the curve of the change of the underflow concentration is shown in fig. 13.

TABLE 11 data sheet of fine fraction tailings 0.2t/m2.h solid flux dynamic thickening experiment results

TABLE 12 data sheet of fine fraction tailings 0.3t/m2.h solid flux dynamic thickening experiment results

TABLE 13 data sheet of fine fraction tailings 0.4t/m2.h solid flux dynamic thickening experiment results

TABLE 14 data sheet of fine fraction tailings 0.5t/m2.h solid flux dynamic thickening experiment results

TABLE 15 data sheet of the dynamic thickening experiment result of the total tailings at 0.2t/m2.h solid flux

TABLE 16 data sheet of the dynamic thickening experiment result of the total tailings at 0.3t/m2.h solid flux

TABLE 17 data sheet of the dynamic thickening experiment result of the total tailings at 0.4t/m2.h solid flux

TABLE 18 data sheet of the dynamic densification experiment result of the total tailings at 0.5t/m2.h solid flux

TABLE 19 data sheet of the results of the 0.2t/m2.h solid flux dynamic thickening experiment of mixed tailings

TABLE 20 data sheet of the results of the dynamic densification experiment of 0.3t/m2.h solid flux of mixed tailings

TABLE 21 dynamic thickening experiment result data table of 0.4t/m2.h solid flux of mixed tailings

TABLE 22 data sheet of the results of the dynamic densification experiment of 0.5t/m2h solid flux of mixed tailings

Through analyzing each group of experimental data in attached tables 11 to 22, it is found that under the combination of unit consumption of different flocculants and solid flux of three tailings, two monitoring indexes of overflow water turbidity and underflow concentration are basically consistent with the change trend of experiment running time, so that the law of overflow water turbidity and underflow concentration on time change is not repeated.

Example 28 to example 33

In the experiment, three factors, namely the cone angle of the thickener, the height of a mud layer and the rotating speed of a rake rack, are selected, and the three factors are respectively leveled; three columns of U6(63) were made three levels by pseudo-leveling to give U6 (3X 3), see Table 7-1.

TABLE 23 pseudo-level conversion of U6(36) to a homogeneous blend design U6 (31X 31)

Experiment number	Cone angle (°)	Height (mm)	Rotating speed (r/min)
				Example 28	1(30)	2(30)	3(3)
Example 29	1(30)	1(25)	2(2)
				Example 30	2(45)	1(25)	3(3)
Example 31	2(45)	3(35)	1(1)
				Example 32	3(60)	2(30)	1(1)
Example 33	3(60)	3(35)	2(2)

The mud layer height transformation rule refers to the mathematical characterization that the mud layer height increases along with the increase of the feeding amount in the experiment process. By researching the rising rule of the small thickener, the change rule of the mud layer in thickeners with different cone angles can be evolved, and the operation condition parameter-feeding time parameter of the thickener is further researched. Whereby a data point map 14 is rendered herein based on observed mud layer height versus time data.

The digital dot diagram is a dot diagram consisting of numbers, and can clearly distinguish the regular relationship among different data groups. Different numbers are used to represent data symbols for distinguishing different groups of data. The figure totally has 6 dot diagrams, each dot diagram is composed of the same Arabic numerals, marked by the Arabic numerals 1-6 and represents different meanings.

In the upper figure 1, the cone angle is 30 degrees, the height of a mud layer is designed to be 30cm, and the rotating speed of a rake frame is 3 r/min; 2, the cone angle is 30 degrees, the height of the mud layer is designed to be 25cm, and the rotating speed of the rake frame is 2 r/min; 3, the cone angle is 45 degrees, the height of the mud layer is designed to be 25cm, and the rotating speed of the rake frame is 3 r/min; 4, the cone angle is 45 degrees, the height of the mud layer is designed to be 35cm, and the rotating speed of the rake frame is 1 r/min; 5, the cone angle is 60 degrees, the height of the mud layer is designed to be 30cm, and the rotating speed of the rake frame is 1 r/min; 6, the cone angle is 60 degrees, the height of the mud layer is designed to be 35cm, and the rotating speed of the rake frame is 2 r/min.

As can be seen from fig. 14, the rate of change of the height of the fine tailings mud layer has a clear relationship with the thickener cone angle. The ascending rate of the rake frames with the same taper angle and different rotation speeds is close to that of the rake frames; the rising speed of the thickener with different cone angles shows that the difference is obvious.

In order to analyze the influence of the cone angle on the mud layer rising speed, the cone angle section and the straight cylinder section are respectively analyzed, and the influence of the cone angle section on the mud layer rising speed and the influence of the cone angle on the straight cylinder section mud layer rising speed are researched. Fig. 15 shows the rise of the cone angle mud layer over time for different thickeners.

It can be derived mathematically that the greater the cone angle of the thickener, the greater the volume of its cone angle, i.e. the 60 cone angle volume is greater than the 45 cone angle volume and the 45 cone angle volume is greater than the 30 cone angle volume. It can be seen from fig. 15 that when the mud is fed for the same time, the smaller the cone angle, the shorter it takes to reach the straight section, indicating a smaller volume. When the height of the mud layer is constant, the time for the thickener with different cone angles to reach is different, which shows that the change rate of the cone angle height is influenced by the size of the cone angle, when the height of the mud layer is 9cm, the feeding time sequentially comprises a 30-degree cone angle, a 45-degree cone angle and a 60-degree cone angle according to the sequence, which shows that the higher the cone angle is, the higher the rising rate is when the height is constant. It can also be understood from fig. 15 that as the cone angle reaches the top of the cone angle, its rate of rise, i.e., the terminal velocity, approaches a constant value, which is analyzed in the second stage, the mudwall high-level section, as shown in fig. 7-5 below.

As can be seen from FIG. 16, the rise rate of the mud layer at different cone angles is typically linearly increased with time. To accurately determine the growth rate, its linear regression analysis (LA), shown below in fig. 17, is its linear regression mathematical model.

The main parameters and fit of the model are described in tables 7-3 below, from which it can be seen that the rise rates for the 6 sets of experiments were 0.289mm/min for group 1, 0.279mm/min for group 2, 0.323mm/min for group 3, 0.277mm/min for group 4, 0.242mm/min for group 5 and 0.268mm/min for group 6, respectively. The fitted models had R2 of 0.996, 0.994, 0.987, 0.994, 0.991, 0.977, respectively.

Further, it was found that the rise rate of the mud layer was around 0.2735mm/min in average value, and the fluctuation of the cone angle was not large (< 10%), and it was considered that the rise rate of the height of the mud layer in the straight barrel section was independent of the cone angle.

TABLE 24 rate of rise of mud layer in cylinder section

According to the concentration experiment result, carrying out main effect analysis to obtain the height of a mud layer and the size of a cone angle, wherein the main effect of the rotation speed of the rake frame on the concentration is as follows in sequence: the height of the mud layer is greater than the rotating speed of the rake frame and the size of the cone angle. When the thickener is designed, the height of a mud layer is taken as a main influence factor for improving the concentration.

Through analysis of the rising rate of the height of the mud layer, the conclusion that the larger the cone angle, the faster the mud layer of the cone angle section rises, and the rising rate of the straight cylinder section is independent of the cone angle is obtained. That is, when the mud layer rising speed is large (when the cone angle is large), the thickener stores less material under the conditions of the same height. In other words, if the cone angle is larger for a given stock of thickener, the height required is larger. Therefore, the cone angle of the proposal is not too large and is set to be 30 degrees, which not only can meet the requirement of storing more materials, but also is beneficial to improving the concentration.

The present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed.

Claims

1. A tailing separation method is characterized by comprising the following steps:

carrying out hydraulic cyclone treatment on the first underflow to obtain settled sand and a second overflow;

filtering the settled sand to obtain a filtrate and a filter cake;

and after a flocculating agent is added into the mixed solution, carrying out second thickening treatment to obtain a third overflow and a second underflow.

2. The tailings separation method of claim 1 wherein the tailings forming the tailings slurry comprise at least one of whole tailings, fine fraction tailings, and graded tailings; or/and

the mass concentration of the tail mortar is 4-16%; or/and

the solid flux of the tail mortar is 0.2-0.5 t/m².h。

3. The tailings separation method of claim 2 wherein the mass fraction of the whole tailings having a particle size of less than 19 μm is greater than 55% based on 100% of the mass of the whole tailings; or/and

the mass of the fine fraction tailings with the particle size of less than 19 mu m accounts for more than 55 percent based on 100 percent of the mass of the fine fraction tailings; or/and

the mass percentage of the graded tailings with the particle size of less than 19 mu m is 6.50 percent based on 100 percent of the mass of the graded tailings.

4. The tailings separation method of claim 2 wherein the flocculant comprises at least one of anionic, non-ionic polyacrylamide; or/and

the flocculant is added into the mixed liquor according to the proportion that 10-80 g of flocculant is added into each ton of tailings; or/and

the flocculant is added in the form of a flocculant solution, and the addition flow rate of the flocculant solution is 33.9-148.4 ml/min.

5. The tailings separation method of claim 4, wherein the anionic polyacrylamide has a weight average molecular weight of 1000 to 1400 ten thousand; or/and

the weight average molecular weight of the nonionic polyacrylamide is 800-1600 ten thousand.

6. The tailings separation method of claim 1 wherein the second thickening step comprises: and treating the mixed solution by adopting a deep cone thickening treatment method.

7. The tailings separation method according to claim 6, wherein the deep cone thickener is provided under the following conditions:

the cone angle of the deep cone thickener is 30-60 degrees; or/and

the diameter of the deep cone thickener is 16-30 m; or/and

the rotating speed of a rake frame of the deep cone thickener is 1-3 r/min.

8. The tailings separation method of claim 1, wherein the pH of the mixed solution is 8.68 to 9.96, and the average pH of the third overflow is 7.73 to 9.98; or/and

the COD value of the mixed solution is 387-23402 mg/L, and the COD value of the third overflow is 387-564 mg/L.

9. The tailings separation method of claim 1, wherein the weight ratio of the tailings contained in the second underflow is 56-62.5%, and the water turbidity of the third overflow is less than 200 ppm.

10. The tailings separation method of claim 1 wherein the second underflow forms the R of the pack_3dThe strength of (A) is more than 3 MPa; or/and

the second underflow forming R of the packing_28dThe strength of (A) is more than 3 MPa.