A method for testing the flocculation network formation time of an ultrafine tailings cemented filling slurry

Abstract

The application provides a kind of ultrafine tailings cemented filling material slurry flocculation network formation time test method, and relates to the technical field of mine filling mining.The application prepares ultrafine tailings cemented filling material slurry and pure ultrafine tailings slurry body, uses dynamic rheometer to carry out strain amplitude test of fixed frequency, obtains the complement of linear viscoelastic region of two kinds of slurry body;Using dynamic rheometer, the frequency scanning test of fixed strain is carried out on the ultrafine tailings cemented filling material slurry, and the equilibrium frequency is obtained;Pre-shearing is carried out on the ultrafine tailings cemented filling material slurry, to ensure that all filling material slurries are in the same repeatable reference state;After the pre-shearing process, the time scanning test of fixed strain and frequency is directly carried out, to determine the flocculation network formation time of the ultrafine tailings cemented filling material slurry.The application helps to deeply understand the flocculation and sedimentation process of ultrafine tailings and the fluidity of ultrafine tailings cemented filling material slurry, so as to optimize the proportioning, and finally improve the utilization rate of ultrafine tailings.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mine filling mining, and particularly relates to a method for testing flocculation network formation time of ultra-fine tailings cemented filling slurry. BACKGROUND

[0002] In the actual mine filling, the fluidity of freshly mixed filling slurry is crucial to the efficiency and cost of mine filling operation. After the filling material is fully mixed and stirred at the ground filling station, it is usually transported to the underground stope by gravity or pumping. If the fluidity of freshly mixed filling slurry is poor, it will not only affect the transportation efficiency, but also cause pipeline blockage, which will cause considerable economic losses to the mine. The key to understanding the fluidity of filling slurry lies in its rheological properties, which determine the response of freshly mixed filling slurry to external load and structural changes during shearing. The microstructure evolution of filling slurry directly affects its rheological parameters. The microstructure evolution of early filling slurry is mainly controlled by the flocculation network of particles and the hydration of cementitious materials, and the flocculation network plays a dominant role in the yield stress of early filling slurry. The formation of the flocculation network requires a certain time, which is of great significance to the yield mechanism of filling slurry. In addition, with the development of mineral processing technology, the tailings are ground finer and finer. The increase of ultra-fine particle content undoubtedly enhances the interaction between particles, and the formation mechanism of the flocculation network is further complicated. Compared with coarse tailings, ultra-fine tailings have slow settling velocity and low strength of filling body, which has become a bottleneck restricting the efficient utilization of ultra-fine tailings. Therefore, accurate measurement of the flocculation network formation time of fine tailings cemented filling slurry helps to deeply understand the flocculation and settling process of ultra-fine tailings and the fluidity of ultra-fine tailings cemented filling slurry, so as to optimize the proportioning and finally improve the utilization rate of ultra-fine tailings.

[0003] In existing researches, when studying the flocculation network of filling slurry, environmental scanning electron microscope (ESEM) or focused beam reflectance measurement (FBRM) technology is usually used to measure the size of flocculation. These two technologies cannot exclude the influence of cementitious material hydration on particle flocculation, and cannot accurately measure the time required for complete formation of the flocculation network. In addition, due to the strong thixotropy of ultra-fine tailings cemented filling slurry, the shearing history has a great influence on the measurement results of the flocculation network formation time. Therefore, how to provide a testing method which can isolate the study of particle flocculation and eliminate the influence of shearing history on the results, and realize real-time monitoring of the flocculation network, so as to accurately measure the flocculation network formation time of ultra-fine tailings cemented filling slurry, has become a technical problem to be solved. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a method for testing the flocculation network formation time of superfine tailings cemented filling slurry, which can be effectively applied in the rheological property analysis of superfine tailings cemented filling slurry, and helps the mine to deeply understand the flocculation and sedimentation process of superfine tailings and the fluidity of superfine tailings cemented filling slurry, so as to optimize the proportioning and finally improve the utilization rate of superfine tailings.

[0005] A method for testing the flocculation network formation time of superfine tailings cemented filling slurry, comprising the following steps:

[0006] Step 1: preparing superfine tailings cemented filling slurry containing cement and pure superfine tailings slurry body not containing cement;

[0007] Step 2: selecting a fixed frequency and a strain amplitude range, performing a strain amplitude test at the fixed frequency by using a dynamic rheometer, and obtaining the linear viscoelastic region complement of the superfine tailings cemented filling slurry and the pure superfine tailings slurry body;

[0008] The linear viscoelastic region complement is the part that the linear viscoelastic region of the pure superfine tailings slurry body is larger than that of the superfine tailings cemented filling slurry;

[0009] Step 3: selecting a fixed strain and a frequency range, performing a frequency scanning test at the fixed strain on the superfine tailings cemented filling slurry by using the dynamic rheometer, and obtaining the equilibrium frequency;

[0010] The fixed strain belongs to the linear viscoelastic region complement of the two kinds of slurries obtained in step 2, a frequency scanning test data image is plotted with frequency as the horizontal coordinate and complex modulus as the vertical coordinate, when the complex modulus starts to stabilize, i.e. the fluctuation is less than a set value, the corresponding frequency is the equilibrium frequency;

[0011] Step 4: setting a pre-shearing rate and a duration, and pre-shearing the superfine tailings cemented filling slurry;

[0012] Step 5: directly performing a time scanning test at the fixed strain and the frequency on the superfine tailings cemented filling slurry after pre-shearing, and determining the flocculation network formation time of the superfine tailings cemented filling slurry.

[0013] The fixed strain is consistent with the fixed strain in step 3, and the frequency is the equilibrium frequency; a time scanning test data image is plotted with time as the horizontal coordinate and storage modulus as the vertical coordinate, when the storage modulus starts to stabilize, i.e. the fluctuation is less than a set value, the corresponding time is the formation time of the filling slurry flocculation network, and the test of the flocculation network formation time of the superfine tailings cemented filling slurry is completed.

[0014] The beneficial effects generated by the above technical solution are as follows:

[0015] The application provides a method for testing flocculation network formation time of superfine tailings cemented filling slurry.

[0016] (1) The application has simple steps and strict design.

[0017] (2) The pre-shearing effect of the application can eliminate the influence of shearing history on the measurement result of the flocculation network formation time of the slurry.

[0018] (3) The application selects two kinds of critical strain supplements and balance frequencies to perform time scanning tests, so that the flocculation of particles can be studied independently, and the influence of hydration of cementitious materials can be excluded.

[0019] (4) The application can monitor the flocculation network in real time, so that the flocculation network formation time of the superfine tailings cemented filling slurry can be accurately measured. In addition, the formation times obtained by filling slurries with different proportions can be directly compared horizontally, and the applicability is strong.

[0020] (5) The application helps to deeply understand the flocculation and sedimentation process of superfine tailings and the flowability of superfine tailings cemented filling slurry, so that the proportioning optimization can be performed, and finally the utilization rate of superfine tailings can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a result graph of the strain amplitude test in the embodiment of the application;

[0022] Figure 2 is a curve graph of the complex modulus changing with the oscillation frequency in the embodiment of the application;

[0023] Figure 3 is a curve graph of the storage modulus of the superfine tailings cemented filling slurry in the embodiment of the application. DETAILED DESCRIPTION

[0024] The specific embodiments of the application will be further described in detail below in combination with the drawings and examples. The following examples are used to illustrate the application, but are not used to limit the scope of the application.

[0025] A method for testing flocculation network formation time of superfine tailings cemented filling slurry, comprising the following steps:

[0026] Step 1, preparing superfine tailings cemented filling slurry containing cement and pure superfine tailings slurry body without cement;

[0027] In this embodiment, the solid concentration of the cement-containing ultrafine tailings cemented backfill slurry and the cement-free pure ultrafine tailings slurry is 74%, the content of tailings particles smaller than 20μm is 20.8%, and the maximum particle size is determined to be no more than 120μm by a Malvern Mastersizer 2000 laser particle size analyzer; the cementitious material content of the cement-containing ultrafine tailings cemented backfill slurry is 7%.

[0028] Step 2: Select a fixed frequency and strain amplitude range, and use a dynamic rheometer to conduct a fixed frequency strain amplitude test to obtain the complement of the linear viscoelastic zone of the ultrafine tailings cemented filling slurry and the pure ultrafine tailings slurry.

[0029] The complement of the linear viscoelastic zone is the portion of the linear viscoelastic zone of the pure ultrafine tailings slurry that is larger than the linear viscoelastic zone of the ultrafine tailings cemented filling slurry.

[0030] In this embodiment, the dynamic rheometer used is an Anton Paar MCR 302. The fixed frequency selected in the strain amplitude test is 1Hz, and the strain amplitude is increased from 0.001% to 20%.

[0031] The results of the strain amplitude test are as follows Figure 1 As shown, CPB represents ultrafine tailings cemented backfill slurry, and TB represents pure ultrafine tailings slurry. Since pure ultrafine tailings slurry does not contain cementing materials, the range of its linear viscoelastic region LVED is larger than that of the ultrafine tailings cemented backfill slurry. The larger portion represents the complement of the linear viscoelastic regions of the two slurries. Here, a strain amplitude of 0.01% is selected for subsequent tests.

[0032] Step 3: Select the fixed strain and frequency range, and use a dynamic rheometer to conduct a fixed strain frequency scanning test on the ultrafine tailings cemented filling slurry to obtain the equilibrium frequency.

[0033] The fixed strain is the complement of the linear viscoelastic regions of the two slurries obtained in step 2. In this embodiment, 0.01% is selected. In the frequency scanning test, the frequency is reduced from 100Hz to 1Hz. The frequency scanning test data image is plotted with frequency as the abscissa and complex modulus as the ordinate. When the complex modulus begins to stabilize, that is, when the fluctuation is less than the set value, the corresponding frequency is the equilibrium frequency. In this embodiment, the fluctuation is set to be less than 5%.

[0034] In this embodiment, the relationship between frequency and complex modulus is as follows: Figure 2 As shown, the complex modulus first decreases and then stabilizes with frequency. The frequency corresponding to the stable region of the complex modulus is the equilibrium frequency. Here, 30Hz is selected for subsequent experiments.

[0035] Step 4: Set the pre-shear rate and duration to pre-shear the ultrafine tailings cemented backfill slurry to ensure that all backfill slurries are in the same repeatable reference state.

[0036] In this embodiment, the pre-shear rate is 100s. -1 The duration is 100 seconds.

[0037] Step 5: Perform time-scanning tests with fixed strain and frequency directly on the pre-sheared ultrafine tailings cemented filling slurry to determine the formation time of the flocculation network in the ultrafine tailings cemented filling slurry.

[0038] The fixed strain is the same as that in step 3, and the frequency is the equilibrium frequency; in this embodiment, the fixed strain is 0.01%, and the frequency is the equilibrium frequency of 30Hz. A time-scan test data image is plotted with time as the x-axis and storage modulus as the y-axis. When the storage modulus begins to stabilize, i.e., the fluctuation is less than the set value, the corresponding time is the formation time of the flocculated network of the filling slurry, thus completing the test of the formation time of the flocculated network of the ultrafine tailings cemented filling slurry. In this embodiment, the fluctuation is set to be less than 2%.

[0039] The evolution of storage modulus of ultrafine tailings cemented backfill slurry is as follows: Figure 3 As shown, under the aforementioned oscillation conditions, the storage modulus increases continuously within the first 500 seconds, then reaches a plateau period lasting 150 seconds. This plateau in storage modulus indicates that the flocculated network in the ultrafine tailings cemented filling material has formed and no longer evolves under oscillating shear. Therefore, the formation time of the flocculated network in the ultrafine tailings cemented filling slurry is 500 seconds. However, when the time exceeds 650 seconds, the storage modulus of the ultrafine tailings cemented filling material increases again. This phenomenon is reasonable and may be related to the change in the CSH nucleation rate caused by the variation in the particle surface dispersion spacing. If we want to further eliminate the influence of CSH nucleation, we can further increase the oscillation frequency.

[0040] The above description is merely a preferred embodiment of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in the embodiments of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in the embodiments of this disclosure.

Claims

1. A method for testing the formation time of flocculated network in ultrafine tailings cemented backfill slurry, characterized in that, Includes the following steps: Step 1: Prepare cement-containing ultrafine tailings cemented filling slurry and cement-free pure ultrafine tailings slurry; Step 2: Select a fixed frequency and strain amplitude range, and use a dynamic rheometer to conduct a fixed frequency strain amplitude test to obtain the complement of the linear viscoelastic zone of the ultrafine tailings cemented filling slurry and the pure ultrafine tailings slurry. Step 3: Select the fixed strain and frequency range, and use a dynamic rheometer to conduct a fixed strain frequency scanning test on the ultrafine tailings cemented filling slurry to obtain the equilibrium frequency. Step 4: Set the pre-shear rate and duration to pre-shear the ultrafine tailings cemented backfill slurry; Step 5: Perform time-scanning tests with fixed strain and frequency directly on the pre-sheared ultrafine tailings cemented filling slurry to determine the formation time of the flocculation network in the ultrafine tailings cemented filling slurry.

2. The method for testing the formation time of flocculated network in ultrafine tailings cemented backfill slurry according to claim 1, characterized in that, The complement of the linear viscoelastic zone in step 2 is the portion of the linear viscoelastic zone of the pure ultrafine tailings slurry that is larger than the linear viscoelastic zone of the ultrafine tailings cemented filling slurry.

3. The method for testing the formation time of flocculated network in ultrafine tailings cemented backfill slurry according to claim 1, characterized in that, After the frequency scanning test described in step 3 is completed, a frequency scanning test data image is plotted with frequency as the abscissa and complex modulus as the ordinate. The frequency corresponding to when the complex modulus begins to stabilize is the equilibrium frequency.

4. The method for testing the formation time of flocculated network in ultrafine tailings cemented backfill slurry according to claim 1, characterized in that, The fixed strain mentioned in step 3 is the complement of the linear viscoelastic regions of the two slurries obtained in step 2.

5. The method for testing the formation time of flocculated network in ultrafine tailings cemented backfill slurry according to claim 1, characterized in that, After the time-scanning test described in step 5 is completed, a time-scanning test data image is plotted with time as the horizontal axis and energy storage modulus as the vertical axis. When the energy storage modulus begins to stabilize, the corresponding time is the formation time of the flocculated network of the filling slurry, thus completing the test of the formation time of the flocculated network of the cemented filling slurry of ultrafine tailings.

6. The method for testing the formation time of flocculated network in ultrafine tailings cemented backfill slurry according to claim 1, characterized in that, The fixed strain mentioned in step 5 is the same as the fixed strain in step 3, and the frequency is the equilibrium frequency.

7. A method for testing the formation time of flocculated network in ultrafine tailings cemented backfill slurry according to claim 3 or 5, characterized in that, The phrase "tends to stabilize" means that the curve fluctuation is less than the set value.

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